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Background: While measuring meniscal extrusion quantitatively is an early risk factor for knee osteoarthritis (KOA), the biomechanics involved in this process are not well understood. This study aimed to investigate the effects of varying degrees of medial and lateral meniscal extrusion and their material softening on knee osteoarthritis progression. Methods: Finite element analysis (FEA) was utilized to simulate varying degrees of meniscal extrusion (1–5 mm) in 72 knee joint models, representing progressive meniscal degeneration and material softening due to injury. Changes in von Mises stress of the cartilage and menisci and the load distribution on the tibial plateau's meniscus and cartilage were studied under balanced standing posture in both healthy and injured knees, and statistical analysis was performed using Spearman correlation. Results: Compared to healthy knees, peak stress in medial compartment tissues increased by over 40% with 4 mm of medial meniscus extrusion, and in lateral compartment tissues with 2 mm of lateral meniscus extrusion. Meniscus extrusion reduced the contact load between the meniscus and femoral cartilage but increased it between the tibial and femoral cartilages, with a maximum increase up to fivefold. Spearman correlation analysis indicated that meniscal extrusion significantly affected peak stress and contact loads in the respective knee compartment (p < 0.001), with a lesser impact on the opposite compartment. Notably, medial meniscal extrusion also significantly increased peak stress in the lateral tibial cartilage (p < 0.05). Conclusions: The quantitative analysis revealed that meniscal extrusion significantly affected the biomechanics of soft tissues within the same compartment, with limited impact on the opposite side. Specifically, Medial extrusion beyond 4 mm significantly affected the biomechanics of the medial compartment, while lateral extrusion over 2 mm had a similar impact on the lateral compartment. Meniscal softening, without altering joint contact characteristics, primarily affected the biomechanics of the meniscus itself, with minimal impact on other soft tissues. [ABSTRACT FROM AUTHOR]

Background: Magnetic resonance imaging (MRI) is the imaging of choice for meniscal extrusion (ME). However, they may underappreciate the load-dependent changes of the meniscus. There is growing evidence that weight-bearing ultrasound (WB US) is more suitable, particularly in revealing occult extrusion. We therefore perform a systematic review and meta-analysis on the validity and reliability of US in diagnosing extrusion. Furthermore, we explored whether it detects differences in extrusion between loaded and unloaded positions and those with pathological (osteoarthritis and meniscal injury) and healthy knees. Methods: The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase were used to perform a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Data pertaining to intra- and interrater reliability of US in measuring meniscal extrusion (ME), its correlation with magnetic resonance imaging (MRI), and head-to-head comparison of potential factors to influence ME were included [loading versus unloading position; osteoarthritis (OA) or pathological menisci (PM) versus healthy knees; mild versus moderate–severe knee OA]. Pooled data were analyzed by random or fixed-effects models. Results: A total of 31 studies were included. Intraclass correlation coefficients (ICC) for intra- and interrater reliability were minimum 0.94 and 0.91, respectively. The correlation between US and MRI was (r = 0.76). US detected ME to be greater in the loaded position in all knees (healthy, p < 0.00001; OA, p < 0.00001; PM, p = 0.02). In all positions, US detected greater extrusion in OA (p < 0.0003) and PM knees (p = 0.006) compared with healthy controls. Furthermore, US revealed greater extrusion in moderate–severe OA knees (p < 0.00001). Conclusions: This systematic review suggests ultrasonography can play an important role in the measurement of meniscal extrusion, with results comparable to that of MRI. However, to what extent it can differentiate between physiological and pathological extrusion requires further investigation, with an absolute cutoff value yet to be determined. Nevertheless, it is an appropriate investigation to track the progression of disease in those with meniscal pathologies or osteoarthritis. Furthermore, it is a feasible investigation to evaluate the meniscal function following surgery. Level of evidence: IV, Systematic review of level III–IV evidence. [ABSTRACT FROM AUTHOR]

Abstract Background While measuring meniscal extrusion quantitatively is an early risk factor for knee osteoarthritis (KOA), the biomechanics involved in this process are not well understood. This study aimed to investigate the effects of varying degrees of medial and lateral meniscal extrusion and their material softening on knee osteoarthritis progression. Methods Finite element analysis (FEA) was utilized to simulate varying degrees of meniscal extrusion (1–5 mm) in 72 knee joint models, representing progressive meniscal degeneration and material softening due to injury. Changes in von Mises stress of the cartilage and menisci and the load distribution on the tibial plateau’s meniscus and cartilage were studied under balanced standing posture in both healthy and injured knees, and statistical analysis was performed using Spearman correlation. Results Compared to healthy knees, peak stress in medial compartment tissues increased by over 40% with 4 mm of medial meniscus extrusion, and in lateral compartment tissues with 2 mm of lateral meniscus extrusion. Meniscus extrusion reduced the contact load between the meniscus and femoral cartilage but increased it between the tibial and femoral cartilages, with a maximum increase up to fivefold. Spearman correlation analysis indicated that meniscal extrusion significantly affected peak stress and contact loads in the respective knee compartment (p

Abstract Background Magnetic resonance imaging (MRI) is the imaging of choice for meniscal extrusion (ME). However, they may underappreciate the load-dependent changes of the meniscus. There is growing evidence that weight-bearing ultrasound (WB US) is more suitable, particularly in revealing occult extrusion. We therefore perform a systematic review and meta-analysis on the validity and reliability of US in diagnosing extrusion. Furthermore, we explored whether it detects differences in extrusion between loaded and unloaded positions and those with pathological (osteoarthritis and meniscal injury) and healthy knees. Methods The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase were used to perform a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Data pertaining to intra- and interrater reliability of US in measuring meniscal extrusion (ME), its correlation with magnetic resonance imaging (MRI), and head-to-head comparison of potential factors to influence ME were included [loading versus unloading position; osteoarthritis (OA) or pathological menisci (PM) versus healthy knees; mild versus moderate–severe knee OA]. Pooled data were analyzed by random or fixed-effects models. Results A total of 31 studies were included. Intraclass correlation coefficients (ICC) for intra- and interrater reliability were minimum 0.94 and 0.91, respectively. The correlation between US and MRI was (r = 0.76). US detected ME to be greater in the loaded position in all knees (healthy, p

Introduction: There is only limited literature available evaluating the preferable treatment for active mid-age or elderly patients presenting with a degenerative medial meniscus root tear (d-MMRT) with medial meniscal extrusion (MME) and early-phase radiographic osteoarthritis (OA), failing to provide solid evidence. The aim of this study was to evaluate early outcomes of medial unicompartimental arthroplasty (mUKA) in active patients presenting a d-MMRT with meniscal extrusion and mild radiographic OA of the knee. To prove this claim we hypothesized that (1) patients with a d-MMRT with initial grade 1–3 KL OA of the medial compartment of the knee present the same pre-operative symptoms as patients with an end-stage grade 4 K-L OA, and that (2) those patients with d-MMRT and low-grade OA achieve the same early clinical and functional outcomes when treated with mUKA compared to patients with end-stage medial OA. Methods: We reviewed the prospectively collected data of 185 patients undergoing robotic-assisted image-based mUKA from January 2021 to July 2022 at a single Institution. We identified two different cohorts of non-consecutive patients: a group of 24 patients undergoing mUKA surgery following d-MMRT combined with K-L grades 1–3 OA (group 1), and a group of 161 patients who underwent mUKA but presenting with an end-stage bone-on-bone K-L grade 4 OA (group 2). Preoperative and postoperative clinical assessments at one-year follow-up included the Oxford Knee Score (OKS), 5-level EQ-5D version (EQ-5D-5L score), and a standard weight-bearing X-ray protocol. The paired t-test was used to compare clinical outcomes and radiologic values of the two cohorts and in-between the two cohorts. Statistical significance was set at p < 0.05. Results: The mean follow-up for group 1 was 16.4 ± 2.5 months, and the mean age at the time of operation was 63 ± 8.6 years with a mean time from diagnosis to intervention of 53 ± 47.5 days. Preoperative impairment was greater in group 1 compared to group 2, but with no significant difference. Postoperatively, both groups showed excellent mean outcomes at 1-year follow-up, with no significant difference. The mean preoperative HKA, mPTA, and LDFA were 176.3 ± 3.1, 88.1 ± 2.3, and 86.6 ± 1.7 respectively. The mean postoperative HKA, coronal femoral component angle, and coronal tibial component angle were 179.1 ± 2.6, 87.2 ± 2.3, and 87.2 ± 3.3. No difference was found between preoperative age, BMI, between the two cohorts. Conclusions: Favorable early clinical outcomes were obtained after mUKA in active mid-age and elderly patients presenting with degenerative medial meniscus root tear and mild isolated medial OA. Patients with mild no bone-on-bone OA but with degenerative medial meniscus root tear and medial meniscal extrusion presented the same or worse pre-operative symptoms as patients with end-stage medial OA and benefit the same from mUKA. [ABSTRACT FROM AUTHOR]

Background: It remains controversial whether meniscal repair causes meniscal extrusion. This study aimed to investigate the effect of inside-out meniscal repair on meniscal dimensions in patients with meniscal tear of the mid-body–posterior horn. Methods: This retrospective study included 75 patients who underwent meniscal repair followed by MRI within 2 weeks after surgery between 2020 and 2022. Patients with a discoid lateral meniscus, pull-out repair, concomitant osteotomy, all-inside repair only, and revision surgery were excluded. Thirty-three meniscal tear treated using an inside-out arthroscopic repair technique were included in the lateral meniscus (LM, n = 19) and medial meniscus (MM, n = 14) tear groups. Thirty-six participants with intact meniscus were included as controls. Meniscal extrusion and posterior shift were measured on coronal and sagittal MRI pre-operatively and within 2 weeks postoperatively. Results: Preoperative coronal extrusion was significantly greater in the LM tear group than in the control group (P = 0.001). Coronal extrusion and posterior shift were significantly smaller postoperatively than preoperatively in the LM tear group (P

Background: Various suture configurations are available for medial meniscus posterior root tear (MMPRT) repair. The modified Mason-Allen (MMA) technique has been proposed as a refixation technique for MMPRT instead of the conventional 2 simple stitches (TSS). This is in view of its superior biomechanical characteristics. Purpose: To perform a systematic review and meta-analysis to compare MMA and TSS configuration techniques for MMPRT repair and identify any differences between the 2 techniques in terms of clinical outcomes, medial meniscal extrusion (MME), and postoperative healing. Study Design: Meta-analysis; Level of evidence, 4. Methods: The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase databases were used to perform a systematic review and meta-analysis using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria with the following search terms: ("meniscus" OR "meniscal injuries") AND ("Mason-Allen" OR "simple stitch" OR "suture techniques"). Data pertaining to all patient-reported outcome measures, postoperative complications, MME, postoperative healing, cartilage degeneration, and progression of knee osteoarthritis were extracted from each study. The pooled outcome data were analyzed using random- and fixed-effects models. Results: After abstract and full-text screening, 6 clinical studies were included. In total, there were 291 patients; 160 underwent MMA fixation, and 131 underwent the TSS technique. The majority of studies had similar surgical techniques regarding repair technique, suture material, tibial fixation, and number and position of tibial tunnels. There were no differences between the groups in terms of patient-reported outcome measures at 14.2 months. Both techniques were also similar in the degree of postoperative MME and meniscal healing. Conclusion: Both suture configurations were equivalent in terms of clinical outcomes, the extent of meniscal extrusion, and postoperative healing. The TSS technique may offer advantages in terms of faster learning curve and shorter operative time. However, randomized controlled trials with large sample sizes, longer follow-up and assessment of chondral degeneration, and presence of knee osteoarthritis are required to assess whether a true difference exists, as the majority of included studies were limited by their retrospective design. [ABSTRACT FROM AUTHOR]

Background: Medial meniscus posterior root (MMPR) tears are recognized as a substantial cause of disability and morbidity. However, meniscus root repair, regardless of technique, is not without potential complications. Purpose: To evaluate the reported incidence of complications and adverse events after isolated MMPR repair. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using Embase, PubMed, and Scopus databases with the following search terms combined with Boolean operators: "meniscus,""root," and "repair." Inclusion criteria consisted of level 1 to 4 human clinical studies in English or English-language translation reporting complications and adverse events after isolated posterior medial meniscus root repairs. The overall incidence of specific complications was estimated from the pooled sample of the included studies. Results: Eleven studies with a total pooled sample of 442 patients were identified. The mean patient age was 58.1 years, while the mean final follow-up time was 37.2 months (range, 12-84.8 months). The overall incidence of complications was 9.7% (n = 43/442), with the most commonly reported complication being progressive degenerative changes within the knee (10.4%; n = 25/240; n = 5 studies). A total of 1.25% (n = 3/240) of patients who experienced degenerative changes required conversion to total knee arthroplasty. Repair failures were reported in 3.1% (n = 10/327; n = 8 studies) of patients. Conclusion: Repairing MMPR tears is critical in preventing accelerated progression of knee osteoarthritis in patients without significant knee osteoarthritis preoperatively. While this repair is still recommended and necessary in appropriate patients, this review found that the incidence of complications after isolated posterior medial meniscus root repair was 9.7%, primarily involving the presence of progressive degeneration, while repair failure was reported in 3% of patients. [ABSTRACT FROM AUTHOR]

Background/objective: For radial tears, all-inside suture (AIS) repair was clearly biomechanically superior, compared to conventional trans-capsular suture (TCS) repairs. However, clinical comparative studies of these two repairs techniques have not to be performed. Therefore, the aim of this study was to compare the clinical outcomes after AIS repair and TCS repairs for isolated radial tear at middle segment of lateral meniscus (RTMLM) in stable knees of young athletes. Methods: Twenty-six athletes (mean age, 19.1 years) underwent AIS repair with the double horizontal suture technique, using SutureLasso™ (Arthrex, Naples, FL) for isolated RTMLM (AIS group), and 20 athletes (mean age, 19.0 years) underwent inside-out repair, one of TCS repairs, with tie-grip suture technique (TCS group). All athletes were assessed for preoperative and two-year postoperative Knee injury and Osteoarthritis Outcome Score (KOOS). At six-month after repair, the lateral meniscal extrusion on mid-coronal plane on MRI and healing status on second-look arthroscopy were also evaluated in all patients. Results: In both groups, KOOS improved to either good or excellent postoperatively, while complete healing was found in only 23 and 25% at second-look arthroscopy. We identified no group-dependent differences in KOOS or healing status on arthroscopy. However, a close examination of failure rates revealed significant lower rates in AIS group relative to that of TCS group (p = 0.048). Moreover, the change from preoperative to postoperative lateral meniscal extrusion in AIS group was significantly smaller than that in TCS group (p = 0.038). Conclusions: AIS and TCS repairs for RTMLM were comparable in providing satisfactory clinical results with low rates of complete healing on arthroscopy. However, AIS repair could have lower failure rate of healing on arthroscopy and minimize postoperative lateral meniscal extrusion more effectively than TCS repair on MRI.

Purpose: Transtibial pullout repair improves the clinical outcomes of medial meniscus (MM) posterior root tears (PRTs); however, reducing MM extrusion remains challenging. Thus, the purpose of this study was to examine the role of additional posterior anchoring (PA) during pullout repair in reducing the severity of MM extrusion compared to pullout repair alone. Methods: Patients who underwent pullout repair with two-cinch stitches (TCS) only or TCS combined with PA (TCS-PA)—deployment of an additional suture anchor in the posteromedial corner of MM—were included retrospectively. MM medial and posterior extrusion (MMME and MMPE), MM extrusion and remaining volume (MMEV and MMRV), and corresponding ratios were evaluated pre-operatively and three months post-operatively using a three-dimensional meniscal model at 10° and 90° of knee flexion and compared within and between groups. Results: A total of 15 and 16 patients treated with TCS and TCS-PA, respectively, were enrolled. At 90° knee flexion, both techniques significantly reduced MMPE (TCS: 4.2 ± 0.7 mm to 3.5 ± 0.6 mm, p < 0.05; TCS-PA: 3.7 ± 0.8 mm to 2.8 ± 0.7 mm, p < 0.05) at three months post-operatively. TCS-PA reduced MMPE more significantly than TCS alone (p < 0.05). Only TCS-PA significantly improved the MMEV and MMRV ratios (39.6 ± 8.9% to 28.1 ± 6.0%, p < 0.05 and 60.4 ± 8.9% to 71.9 ± 6.0%, p < 0.05, respectively). Significance was not found in all other comparisons. Conclusions: Both techniques improved MMPE at knee flexion at the three month follow-up, with TCS-PA providing significantly superior results. Our findings support the evidence that the application of PA may be an effective surgical option for alleviating persistent MMPE. [ABSTRACT FROM AUTHOR]

Background: Meniscal extrusion often persists after a medial meniscus root repair. If the meniscus is extruded, the function of the meniscus as a load-sharing device and secondary knee stabilizer is compromised. Hypothesis: It was hypothesized that repairing the meniscotibial ligament (MTL) would decrease meniscal extrusion in the settings of both an isolated MTL tear and a repaired medial meniscus root while also improving medial compartment contact mechanics. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen cadaveric knees (mean age, 50.5 years) were tested in 5 conditions: intact, MTL deficiency, MTL deficiency + posterior medial meniscus root deficiency, MTL deficiency + posterior medial meniscus root repair, and MTL tenodesis + posterior medial meniscus root repair. Specimens were mounted to a load frame that applied a 1000-N axial load. Joint contact pressures were measured using thin pressure sensors, and the peak and mean pressures were analyzed. Ultrasound was used to measure meniscal extrusion. Results: The MTL tear in isolation resulted in significant meniscal extrusion compared with the intact state (P = 0.035) without a detectable difference in medial compartment pressures. The addition of a root tear to the MTL tear state resulted in significantly more extrusion (P = 0.001) and significant increases in medial compartment pressure (P =.030) compared to the MTL tear state. Root repair alone restored extrusion, mean contact pressure, and peak contact pressure back to the intact state (P >.05). Conclusion: This study showed that MTL disruption led to increased meniscal extrusion in a cadaveric model. Unlike the root tear state, MTL disruption did not change contact mechanics. Furthermore, root repair alone was sufficient in restoring intact biomechanics and extrusion. Clinical Relevance: This study may help clinicians understand the origin of medial meniscus root tears and aid in the decision-making process for whether to add an MTL tenodesis in the setting of root repair. [ABSTRACT FROM AUTHOR]

Background: Meniscal extrusion has become increasingly utilized when evaluating meniscus root abnormalities. However, no consensus definition or approach exists on how to measure extrusion. Purpose/Hypothesis: The purpose of this study was to evaluate the extent of heterogeneity in meniscal extrusion measurement techniques and reported extrusion values in knees with posterior medial meniscus root tears (PMMRTs). We hypothesized that meniscal extrusion measurement techniques would vary considerably throughout reported studies, with resultant wide-ranging published extrusion values. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The inclusion criteria consisted of all clinical and cadaveric studies reporting on meniscal extrusion after PMMRTs, excluding studies lacking data in full extension, those presenting only semiquantitative analyses, articles reporting only differences in meniscal extrusion, and review articles. Results: A total of 45 studies were included. Imaging modality types included magnetic resonance imaging (89%), 3-dimensional reconstruction with computed tomography (7%), linear displacement transducers (2%), and a combination of magnetic resonance imaging and ultrasound (2%). The 3 most commonly used landmarks to acquire coronal images for meniscal extrusion measurements were the medial collateral ligament (38%), the midpoint of the anterior-posterior length of the medial meniscus (23%), and the middle of the medial femoral condyle (19%). The pooled mean extrusion values according to the measurement location were 3.5 ± 0.7 mm, 3.9 ± 0.8 mm, and 4.5 ± 2.1 mm, respectively, with no significant differences noted between the modality types (P =.23). The pooled mean meniscal extrusion from all included studies was 3.2 ± 2.0 mm. Conclusion: Substantial variation exists in measurement techniques for meniscal extrusion, particularly as it relates to the coronal cross-sectional reference location. Further studies should aim to provide clear descriptions of the measurement method and have uniform measurement methodology to allow comparisons and pooling between studies. [ABSTRACT FROM AUTHOR]

BACKGROUND. The extent of medial meniscal extrusion (MME) that is associated with structural and symptomatic progression of knee osteoarthritis has not been defined yet. OBJECTIVE. The purpose of our study was to investigate MRI-based thresholds of MME that are associated with structural progression of knee degenerative disease and symptoms over a period of 4 years. METHODS. We studied 328 knees of 235 participants that were randomly selected from the Osteoarthritis Initiative cohort. MME was quantified on coronal sections of intermediate-weighted MRI sequences obtained at 3 T. Knee pain and cartilage abnormalities were measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale and the cartilage whole-organ MRI score (WORMS). General estimating equations with logistic regression models were used to correlate baseline MME and changes in pain (WOMAC) and cartilage damage (WORMS). ROC analyses were performed to determine the area under the ROC curve (AUROC). Individual thresholds were determined by maximizing the product of sensitivity and specificity. RESULTS. The AUROC for predicting progression of knee pain, medial compartment cartilage damage, and medial tibial cartilage damage were 0.71, 0.70, and 0.72, respectively, and the individual thresholds for MME were 2.5, 2.7, and 2.8 mm. A single threshold of 2.5 mm was determined by maximizing the mean of the product of sensitivity and specificity of the three outcome variables (knee pain progression, medial compartmental cartilage damage progression, and medial tibial cartilage damage progression). CONCLUSION. MME was associated with knee pain and cartilage damage progression over 4 years. A single threshold of 2.5 mm was found to be the most useful threshold for predicting knee pain, medial compartment cartilage damage progression, and tibial cartilage damage progression over 4 years. CLINICAL IMPACT. This threshold could be used to standardize the diagnostic criterion of extrusion and to better characterize the risk for subsequent structural and symptomatic progression of knee osteoarthritis.

Abstract Background Patients with partial medial meniscus posterior root tears (MMPRTs) sometimes require arthroscopic pullout repair because of their intolerable/repeated knee pains and continuous disturbance in gait during activities of daily living. However, the predisposing factors for future knee surgery in patients with partial MMPRTs remain unclear. We compared the findings of magnetic resonance imaging (MRI) between patients who underwent pullout repair and nonoperative management following partial MMPRTs. Methods Twenty-five patients who required arthroscopic repair for partial MMPRTs and 23 patients who were managed nonoperatively were evaluated during a mean follow-up period of 27.1 months. Sex, age, height, body weight, body mass index, duration from onset to initial MRI, MRI findings, and medial meniscus (MM) extrusion were compared between the two groups. Linear regression analysis was used to assess the correlation between MM extrusion and duration from onset to MRI examination. Results No significant differences were observed between the pullout repair and nonoperative management groups in terms of patient demographics and the positive ratio of MRI-based root tear signs. However, absolute MM extrusion in the pullout repair group (3.49 ± 0.82 mm) was larger than that in the nonoperative management group (2.48 ± 0.60 mm, P 3 mm) was detected more frequently in the pullout repair group than in the nonoperative management group (P 3 mm cases was 9.662. Linear regression analysis revealed a fair correlation between the duration from onset to MRI and MM extrusion only in the pullout repair group (0.462 mm/month increase in MM extrusion). Conclusions This study demonstrated that more severe MM extrusions were observed in the pullout repair group than in the nonoperative management group. Major extrusion (> 3 mm) was also observed more in the pullout repair group than in the nonoperative group. Assessing MM extrusion and its severity can help determine a valid treatment for patients with partial MMPRTs. Level of evidence IV, Retrospective comparative study.

Purpose: Given that no studies have assessed the correlation between improvements in medial meniscus extrusion (MME) and clinical outcomes after medial opening-wedge high tibial osteotomy (MOWHTO), the present study aimed to measure the improvement in MME after MOWHTO and to investigate the correlation between the remaining postoperative MME and MOWHTO clinical outcomes by subgroup analysis. Methods: This study included 79 patients (80 knees) who underwent MOWHTO with a minimum follow-up of 2 years. MME was measured pre- and postoperatively through magnetic resonance imaging after an average of 19.8 months following MOWHTO surgery. Clinical outcomes were evaluated according to the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner Activity Scale, and the Short-Form 36 questionnaire. In subgroup analysis, postoperative MME was classified into non-pathologic (≤ 3 mm) and pathologic (> 3 mm) groups. The clinical outcomes of the two groups were compared using Mann–Whitney U tests. A regression analysis was performed to determine the preoperative and postoperative characteristics associated with the improvement of MME. Results: The mean (± standard deviation) values for pre- and postoperative MME were 3.6 (± 1.8) mm and 2.8 (± 1.5) mm, respectively (p < 0.001). In the subgroup analysis of postoperative MME, the non-pathologic group showed better improvement of KOOS than the pathologic group. Preoperative hip-knee-ankle angle was correlated with the improvement of medial meniscal extrusion in both univariate (p = 0.049) and multivariate (p = 0.015) analyses. Conclusion: The MME improved after MOWHTO, and the clinical outcomes were better for patients with a postoperative MME of less than 3 mm than for those with more than 3 mm. MME improvement after MOWHTO was correlated with preoperative varus alignment of the lower extremities. Level of evidence: III (Retrospective cohort study). [ABSTRACT FROM AUTHOR]

Abstract The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics.

Background: Medial meniscal extrusion (MME) has received significant interest because of its correlation with medial meniscus root tears (MMRTs), its potential as a diagnostic tool, and its significance in the progression of knee osteoarthritis (OA). Purpose: To (1) evaluate if MMRTs significantly increase MME compared with nonroot tears (NRTs) and no tears and (2) determine the clinical outcomes of increased MME. Study Design: Systematic review; Level of evidence, 4. Methods: Electronic database searches of PubMed, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were conducted on June 6, 2022, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist criteria. The searches were conducted using the keywords "meniscus tear" and "extrusion." No restrictions were placed on the date of publication. Quality and sensitivity assessments were conducted on included studies. Major MME was defined as an extrusion ≥3 mm. Results: Twenty-two studies involving 7882 knees were included. Compared with patients with NRTs, those with MMRTs had a 1.12-mm greater mean absolute meniscal extrusion (AME) and were 3.45 times more likely to have major MME (P <.001 for both). Compared with patients with no tears, those with MMRTs had a 2.13-mm greater AME (P <.001). Within patients with MMRT, those with widely displaced MMRT had a 1.01-mm greater AME compared with nondisplaced MMRT (P <.001). Patients with OA had a 0.73-mm greater AME and were 3.86 times more likely to have major MME compared with patients without OA (P <.001 for both). Within patients who were not stratified according to MMRT, NRT, or no tears, those who eventually developed OA had a 0.79-mm greater AME than those who did not have OA (P =.02). Conclusion: Patients with MMRTs had higher MME values compared with those with other types of meniscal tears and those without any meniscal tears. Patients with knee OA were more likely to have higher MME compared with those without OA. [ABSTRACT FROM AUTHOR]

BACKGROUND: The research on the effect of meniscus injury on knee osteoarthritis is mostly concentrated in the tibiofemoral compartment. There are reports on the correlation between meniscus extrusion and patellofemoral osteoarthritis outside China, but there are few related studies in China.OBJECTIVE: To explore the association between meniscus extrusion and patellofemoral osteoarthritis based on published data from the Osteoarthritis Initiative. METHODS: Totally 1 109 participants with complete MRI Osteoarthritis Knee Score and other clinical information at baseline were selected. Meniscal tear, maceration, extrusion, patellofemoral cartilage and bone marrow lesions were scored by MRI Osteoarthritis Knee Score semi-quantitative scoring system. Gender, age, race, body mass index, history of knee injury, and history of surgery were collected by questionnaire. Logistic regression analysis was used to determine the relationship between meniscal extrusion and patellofemoral osteoarthritis. RESULTS AND CONCLUSION: (1) The cross-sectional study showed that patients with medial and lateral meniscus extrusion had a high incidence of any cartilage injury, full-thickness cartilage injury, and bone marrow lesions in medial and lateral patellofemoral joint. (2) Logistic regression analysis showed that after adjusting for confounding factors (adjustment model 2), the medial meniscus extrusion was positively correlated with any cartilage injury of the medial patellofemoral joint [OR: 2.4(95% CI: 1.6, 3.6)] and full-thickness cartilage injury [OR: 1.5(95% CI: 1.0, 2.1)]; there was no correlation between medial meniscus extrusion and medial patellofemoral joint bone marrow lesions without adjustment [OR: 0.8(95% CI: 0.6, 1.1)] and after adjustment for confounding factors [OR: 1.3(95% CI: 0.9, 1.8)]. (3) After adjusting for confounding factors (adjustment model 2), lateral meniscus extrusion was positively correlated with any cartilage injury of the lateral patellofemoral joint [OR: 2.1(95% CI: 1.0, 4.5)] and full-thickness cartilage injury [OR: 2.3(95% CI:1.1, 4.6)]; while without adjusting for confounding factors [OR: 1.7(95% CI: 1.0, 2.9)], lateral meniscus extrusion was positively correlated with bone marrow lesions of the lateral patellofemoral joint, but not after adjustment for confounding factors [OR: 1.1(95% CI: 0.6, 2.1)]. (4) Meniscus extrusion was positively correlated with cartilage injury of patellofemoral joint among Americans based on published data from the Osteoarthritis Initiative. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the effects of arthroscopic meniscal centralization reinforcement for a medial meniscus (MM) posterior root defect on knee kinematics and meniscal extrusion in the anterior cruciate ligament reconstructed (ACLR) knee. The hypothesis was that the medial meniscus centralization would reduce extrusion and anterior laxity in ACLR knee with a medical meniscal defect. Methods: Fourteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under the following loading conditions: (a) an 89.0 N anterior tibial load, (b) 5.0 Nm internal and external rotational torques, (c) a 10.0 Nm valgus and varus loadings, and (d) a combined 7.0 Nm valgus moment and then a 5.0 Nm internal rotation torque as a static simulated pivot shift. The tested knee states included: (1) anatomic single-bundle cruciate ligament reconstruction with intact medial meniscus (MM Intact), (2) anatomic single-bundle cruciate ligament reconstruction with medial meniscus posterior root defect (MM Defect), (3) Anatomic single-bundle cruciate ligament reconstruction with medial meniscus arthroscopic centralization (MM Centralization). Medial meniscus arthroscopic centralization was performed using 1.4 mm anchors with #2 suture. The MM extrusion (MME) was measured using ultrasound under unloaded and varus loading conditions at 0° and 30° of flexion. Results: Anterior tibial translation (ATT) increased significantly with MM posterior root defect compared to MM intact at all flexion angles. With MM centralization, ATT was not significantly different from the intact meniscus at 15° and 30° of flexion. Meniscus extrusion increased significantly with the root defect compared to intact meniscus and decreased significantly with meniscal centralization compared to the root defect at both flexion angles. Conclusions: In ACL reconstruction, cases involving irreparable medial meniscal posterior root tears, applying arthroscopic centralization for avoiding the meniscal extrusion should be considered. Clinically, in ACL reconstruction cases with irreparable medial meniscal posterior root tears, applying arthroscopic meniscal centralization for avoiding the meniscal extrusion should be considered. Meniscal centralization decreases the extrusion of the MM and offers improvements in knee laxity. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to generate more information on the etiology and pathogenesis of medial (MM) and lateral (LM) meniscus root tears. Our hypothesis was that root tears of the MM predominantly result from degenerative damage, whereas root injuries of the LM are mainly of traumatic origin. Methods: Consecutively, 53 patients with a root tear of the medial meniscus (MMRT) and 51 patients with a root tear of the lateral meniscus (LMRT) were included in this study. The diagnosis was confirmed radiologically by MRI as well as arthroscopically. In addition to patient-specific data such as age, BMI and trauma history, the leg axis was determined and accompanying injuries (ligamentous and chondrogenic) were documented. Results: The mean age of the MMRT group was 57.2 (± 11.2) years, and that of the LMRT group 33.9 (± 11.4) years. The BMI was significantly higher in the MMRT group compared to the LMRT (30.5 vs. 25.1). 82.4% of patients in the LMRT group demonstrated an accompanying anterior cruciate ligament (ACL) rupture, whereas only 5.7% of the MMRT were associated with an ACL injury. A trauma was described in only 13.2% of patients of the MMRT group in contrast to 88.2% of the LMRT group. An extrusion > 3 mm of the MM in the coronal plane of MRI images could be detected in 86.8% of patients, whereas in the LMRT group, it was 15.7%. The mechanical varus angle was 5.6° in the MMRT group and 2.4° in the LMRT group. The rate and degree of concomitant cartilage damage in the affected compartment was significantly higher in the group with medial root injuries than in the group with lateral root tears. Conclusions: The root injuries of the MM and LM show significant differences in terms of patient age, etiology and accompanying injuries. Root injuries to the medial meniscus are mostly of non-traumatic origin and more likely to occur in the context of medial osteoarthritis and varus deformity of the knee. Lateral root tears tend to be predominantly traumatic and are frequently associated with ACL ruptures. However, in the MMRT group, a small subgroup with a traumatic etiology and in the LMRT group a small subgroup of patients with non-traumatic etiology could be identified. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Meniscal extrusion (ME) is strongly correlated with cartilage wear and osteoarthritis (OA), be-cause of the altered kinematic and the decreased contact area between the tibia and femur. The aim of this narrative review is to analyze the process of ME, focusing on the possible causes, and to evaluate the correlation between ME and knee OA, in order to provide early diagnosis and treatments. Studies written in English that analyzed the causes of ME, provided indications re-garding diagnosis and treatment, and evaluated the relation between ME and early OA were in-cluded. Injuries, degeneration of the meniscal substance and meniscus root tears are associated with significantly increased ME. An extruded meniscus could be a manifestation of other pa-thologies such as disruption of coronary ligaments, cartilage loss, knee malalignment, ligament injuries, or OA. ME is strongly associated with osteoarthritis features, particularly with bone marrow lesion and cartilage damage. Magnetic resonance imaging represents the gold standard for the detection of ME. The severity of the medial meniscus extrusion may also affect healing af-ter repair, and meniscus extrusion is not completely reduced by meniscus posterior root tear re-pair. In this study, we proved that ME represents an important risk factor for early knee OA. We provided alternative theories of ME, such as meniscal fibers injury first and “dynamic extrusion of the menisci”. The phenomenon of aging has been described as a new concept in the etiology of ME. Finally, we stated all the main techniques and characteristics of the diagnostic process, as well as the current knowledge in the therapeutic field. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate graft survivorship and report the functional and radiographic results of Meniscal allograft transplantation (MAT) throughout a minimum 15-year follow-up period. Methods: Fifty-one patients that had undergone an isolated MAT procedure during the period studied were included. The results were assessed with the Lysholm and Tegner scores as well as the Visual Analog Scale. Magnetic resonance imaging and a complete radiographic series were carried out to determine the degree of meniscal extrusion and joint space narrowing. A comparison was made between the radiological findings of the last follow-up, the 5-year mid-term follow-up and those from the preoperative period. Results: Thirty-eight patients were available for the final follow-up. The mean follow-up was 17.4 years. There were 23 (60.5%) medial menisci and 15 lateral menisci (39.4%). Meniscal extrusion increased from the 29.7% ± 14.9 obtained at the 5-year follow-up to the 72.5% ± 22.5 seen at the end of the follow-up (p = 0.0001). The joint space distance was almost unchanged from the initial evaluation (3.3 ± 1.5 mm) to the 5-year follow-up measurement (3.1 ± 1.7 mm, n.s.). However, it did decrease at the last follow-up (1.9 ± 1.5 mm, p < 0.05). The functional outcomes improved from the preoperative period to the mid-term follow-up and later worsened at the final follow-up. The mean preoperative Lysholm score at the initial follow-up was 61.5 ± 9.6, 86.9 ± 10.9 for the 5-year evaluation and stood at 77.4 ± 11.5 (p = 0.0001) at the final follow-up. Regarding the Tegner score, those pre-operative scores were compared to the ones at the last follow-up (median: 3; range 0–6 vs. 5.5; 3–6, respectively; p = 0.0001). The VAS went down from 6.6 ± 1.7 at the initial evaluation to 2.5 ± 1.9 at the final follow-up (p = 0.0001). The joint-space width remained unchanged from the initial evaluation (3.35 ± 1.5 mm) up to the 5-year follow-up measurement (3.1 ± 1.7 mm, n.s.). However, this joint-space distance had decreased by the last evaluation in the long-term follow-up (1.9 ± 1.4 mm, p < 0.05). Five patients (13.1%) presented with a MAT failure at 5 years, which was followed by extirpation of the meniscal graft. At the final follow-up, a total of 16 patients (42.1%) presented with a failure. At that time, there were 4 more MAT removals and seven patients that required a total knee replacement. The mean time to failure of the meniscal graft was 206.2 months ± 13.4 (18.0 years). Conclusions: Meniscal allograft transplantation produces good functional results at a minimum 15-year follow-up. However, degenerative arthritis in the affected compartment progressed during that period. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to find a correlation between bone marrow lesions (BMLs) in knee MRI and pathologies of joint structures. In addition, according to the six-letter system classification, the authors analyzed a potential association between the area affected by BMLs and the specific type of joint lesion. Methods: The authors screened all the knee MRIs performed in the investigation center between 2017 and 2018 to identify the presence of BMLs. The lesions were then categorized following the "six-letter system". The authors searched the presence of associated meniscal, chondral or ligamentous lesions. Finally, the authors researched a correlation between the lesion type described by the six-letter system classification and the associated lesions. Results: MRI exams of 4000 patients were studied, identifying 666 BMLs. The associated lesions were collected for all patients, resulting in an overall prevalence of related lesions in almost 90% of patients. The authors found a statistical significance for type TLD (Tibia-Lateral-Articular) and ACL rupture. The study suggests a strong positive correlation between type E (Edge) and meniscal fracture or extrusion. Conclusion: BMLs in the knee are associated in 90% of cases with a radiological sign of related injury to the joint structures. The six-letter system of BMLs type TLD can be considered a sign of ACL rupture and type E as a high suspicious sign for meniscal extrusion. Those very typical BML patterns can help the clinician in the diagnosis of ACL tears and meniscal extrusion. Furthermore, the presence of a BML must be, for the clinician, a high suspicious sign of joint-related injuries. Level of evidence: Level 1. [ABSTRACT FROM AUTHOR]

Background and Objectives: Studies analyzing magnetic resonance imaging (MRI) after simultaneously performing lateral meniscal allograft transplantation (MAT) and capsulodesis are currently rare. This study aimed to compare the MRI results between the group that performed lateral MAT alone and the group that performed both lateral MAT and capsulodesis simultaneously. Materials and Methods: A total of 55 patients who underwent lateral MAT with a 1-year follow-up MRI were included. The patients were divided into two groups according to the surgical procedure: group I (isolated lateral MAT, n = 26) and group C (combined lateral MAT and capsulodesis, n = 29). Differences between groups were compared regarding subjective knee scores, graft extrusion, graft signal, articular cartilage loss, and joint space width (JSW). Results: The subjective knee scores improved significantly in both groups (all, p < 0.001), and there were no significant differences in these scores between both groups at the 1-year follow-up. Group C showed less coronal graft extrusion at the 1-year follow-up (1.1 ± 1.7 mm vs. 2.4 ± 1.8 mm, p < 0.001). Pathologic coronal graft extrusion (≥3 mm) was found in seven (26.9%) patients in group I and three (10.3%) in group C. Concerning the graft signal, group C showed less grade 3 signal intensity in the posterior root of the graft. There were no significant differences in preoperative and postoperative cartilage status between groups. Regarding JSW, there were no significant differences in postoperative JSW between both groups. However, in group C, JSW significantly increased from 3.9 ± 0.4 mm to 4.5 ± 1.4 mm (p = 0.031). Conclusions: In lateral MAT, capsulodesis (open decortication and suture anchor fixation) could reduce graft extrusion without complications. In the future, large-volume and long-term prospective comparative studies are needed to confirm the clinical effects following capsulodesis. [ABSTRACT FROM AUTHOR]

Despite the clinical benefits over nonoperative treatment or meniscectomy, the clinical outcomes of surgical repair for medial meniscus posterior root tear (MMRT) remain suboptimal, which may be attributed to the insufficient restoration of meniscal hoop tension during surgery.To analyze the clinical outcomes of surgical repair of MMRT based on the appearance of the meniscal tension observed immediately after surgery.Cohort study; Level of evidence, 3Electronic medical records of patients who underwent arthroscopic transtibial pull-out repair of MMRT between 2010 and 2021 were retrospectively reviewed. Patients with at least a 2-year follow-up and whose overall meniscal status after the surgical repair could be evaluated via arthroscopic images or videos were eligible to be included. Patients were classified based on the presence of the curtain-cliff sign, potentially implying insufficient postoperative meniscal hoop tension (group 1, patients without the curtain-cliff sign; group 2, patients with the curtain-cliff sign). Regression analysis was performed to evaluate whether the curtain-cliff sign reflects postoperative meniscal extrusion. Subsequently, comparative analyses were conducted between the 2 groups regarding baseline demographic data, clinical scores, intraoperative data, and radiologic parameters.A total of 79 patients were included (group 1, 59 patients; group 2, 20 patients). Regression analysis revealed a significant association between the curtain-cliff sign and postoperative meniscal extrusion, suggesting its potential to reflect the postoperative meniscal tension. In the between-group comparisons, there were no differences in baseline demographic data, preoperative clinical scores, and preoperative radiologic variables. However, at the final follow-up, group 2 showed a significantly lower International Knee Documentation Committee subjective score compared with group 1 (group 1, 61.7 ± 14.4; group 2, 52.9 ± 12.5; P = .017), while no significant differences were found in the visual analog scale for pain score and Lysholm score. Additionally, group 2 exhibited significantly higher postoperative meniscal extrusion compared with group 1, which was measured at both the midpoint of the medial femoral condyle (group 1, 4.0 ± 1.1 mm; group 2, 5.1 ± 1.5 mm, P = .004) and the posterior border of the medial collateral ligament (group 1, 4.4 ± 1.2 mm; group 2, 5.7 ± 1.5 mm; P = .004), with more pronounced progression compared with the preoperative status at these sites. Consistently, the progression of both the osteoarthritis grade and the hip-knee-ankle angle compared with preoperatively was significantly greater in group 2.In patients in whom the restoration of meniscal tension appears insufficient immediately after surgical repair of MMRT, relatively poor clinical outcomes can be anticipated. The findings of this study suggest that efforts to reinforce meniscal tension may be required during surgical repair of MMRT in some cases, especially those showing the curtain-cliff sign. [ABSTRACT FROM AUTHOR]

Abstract Background Meniscus root tear is an uncommon but detrimental injury of the knee. Hoop stress is lost during meniscus root tear, which can lead to excessive tibiofemoral contact pressure and early development of osteoarthritis. Posterolateral meniscus root tears (PLRT) are more commonly associated with anterior cruciate ligament (ACL) tears. As the lateral compartment is less congruent than the medial compartment, it is more susceptible to a shearing force, which is increased in the ACL-deficient knee. In accordance with the compressive axial load, the increase in the tibial slope would generate a greater shearing force. The additional lateral compartment mobility caused by ACL tear should be reduced after ACL reconstruction (ACLR). However, there is a lack of evidence to conclude that ACLR can sufficiently limit the effect of large tibial slope (LTS) on the healing after PLRT repair. This study aimed to evaluate whether a steep LTS would be a risk factor for poorer clinical outcomes after PLRT repair concomitant with ACLR. Methods In this retrospective study, a chart review was conducted to identify patients with concomitant unilateral primary ACLR and PLRT repair. Patients with a partial tear or healed tear were excluded. Postoperative MRI and clinical assessments were performed at a mean follow up of 35 months. MRI data was used to measure the LTS, medial tibial slope (MTS), coronal tibial slope (CTS), the lateral-to-medial slope difference (LTS-MTS) and meniscus healing and extrusion. Functional outcomes were evaluated by patient-reported outcomes (International Knee Documentation Committee [IKDC], Lysholm and Tegner scores) and KT-1000 arthrometer assessment. Interobserver reproducibility was assessed by two reviewers. Results Twenty-five patients were identified for the analysis. Patients with larger LTS and larger LTS-MTS differences were shown to be correlated with poorer IKDC scores after surgery (R = -0.472, p = 0.017 and R = -0.429, p = 0.032, respectively). Herein, patients with LTS ≥ 6° or LTS-MTS ≥ 3° demonstrated poorer IKDC scores. Conclusion A large LTS (≥ 6°) and a large difference of LTS-MTS (≥ 3°) were shown to be risk factors for poorer functional and radiological outcomes for PLRT repair in patients after ACLR. Clinically, closer monitoring and a more stringent rehabilitation plan for patients with LTS ≥ 6° or LTS-MTS ≥ 3° would be recommended.

OBJECTIVE:To determine the relationship of meniscal damage to magnetic resonance imaging (MRI) features of compartment-specific patellofemoral joint (PFJ) osteoarthritis (OA) at baseline and 2 years later. METHOD:Individuals from a prospective cohort of individuals aged 50-79 with or at risk of knee OA were included. At the 60-month and 84-month study visit, Whole-Organ MRI Score (WORMS) was used to assess meniscal tears and extrusions as well as cartilage damage and bone marrow lesions (BMLs) in the medial and lateral patella and trochlea. Worsening of structural features was defined as any increase in WORMS score from 60 to 84 months. Logistic regression was used to determine the cross-sectional and longitudinal relation of meniscus damage to features of compartment-specific PFJ OA. RESULTS:Relative to knees without lateral meniscal pathology at baseline, those with grades 3-4 lateral meniscal tear and extrusion had greater risk of worsening of cartilage damage in the lateral PFJ 2 years later (Risk ratio: 1.7 [95% CI: 1.1-2.7) and (1.7 [1.2-2.5]), respectively. Relative to those without medial meniscal pathology at baseline, those with grades 1-2 (0.6 [0.4-0.9]) and 3-4 (0.7 [0.5-1.0]) medial meniscal tears had lower risk of worsening of BMLs in the medial PFJ 2 years later. CONCLUSION:Meniscal tear and extrusion are associated with increased risk of medial and lateral PFJ OA and more severe meniscal pathology is associated with worsening of PFJ OA 2 years later. Lateral meniscal pathology appears to be more detrimental to the lateral PFJ.

Introduction: Medial unicompartmental knee arthroplasty (mUKA) requires full-thickness cartilage in the lateral compartment, but slight damage of the cartilage surface can be ignored. However, as this statement lacks literature support, we investigated whether slight cartilage damages in the weight-bearing area of the lateral femoral condyle would affect the outcome of mUKAs. Materials and methods: Outerbridge grading was performed on the cartilage in the weight-bearing area of the lateral femoral condyle intraoperatively. The patients, grouped as normal or as having lateral condyle cartilage of Outerbridge grade 1–2 (slight cartilage damage), underwent mUKA. Full-length lower extremity radiographs were taken and hip–knee–ankle angles (HKAAs) were measured both preoperatively and postoperatively. Using magnetic resonance imaging, the lateral meniscal extrusion distance was also measured. In addition, the Oxford Knee Score (OKS) was assessed preoperatively and at the last follow-up, in addition to the patient satisfaction assessment. Results: We enrolled 152 knees of 142 patients proposed for mUKAs. The mean age of participants was 69.5 years (51–89 years) and they were followed up for a mean of 25.4 months (15–44 months). There was no significant difference in preoperative (p = 0.746) and postoperative (p = 0.202) mean OKS between the normal, Outerbridge grade 1 and Outerbridge grade 2 groups. While the normal group had a higher change in OKS than the group with cartilage damage, this difference was not significant (p = 0.910). The UKA corrected the patients' mean HKAA from 171.1° (preoperatively) to 176.1° (postoperatively). From all patients, only four had slight lateral meniscus extrusion with MEDs of ≤ 0.25 mm. With the exception of one patient with a poor outcome in normal group, the rest were satisfied with the outcome of mUKA. No patients had prosthesis-related complications or revision surgery. Conclusions: Cartilage damage of Outerbridge grade 1 and grade 2 in the weight-bearing area of the lateral femoral condyle will not compromise the short-term outcome of medial mobile-bearing UKA. [ABSTRACT FROM AUTHOR]

Objectives: It is essential to know the normal extrusion measures in order to detect pathological ones. In this study, we aimed to define some normal reference values for meniscal extrusion in the normal knees during different ranges of motion. Methods: The amount of anterior and posterior portion of meniscal extrusion among 21 asymptomatic volunteers (42 knees) were tracked in 0, 45, and 90° of knee flexion using an ultrasound machine. The repeated measures analysis of variance (ANOVA) was used to show the interaction between the amounts of meniscal extrusion and the different degrees of knee flexion. Results: The anterior portion of the lateral menisci at full knee extension (0.59 ± 1.40) and the posterior portion of the medial menisci during 90° flexion (3.06 ± 2.36) showed the smallest and the highest mean amount of extrusion, respectively. The normal average amounts of anterior extrusion were 1.12 ± 1.17 and 0.99 ± 1.34 mm for medial and lateral menisci, respectively. The posterior meniscal normal extrusions were significantly increasing in both medial and lateral menisci during the survey (F = 20.250 and 11.298; both P values <.001) as they were measured 2.37 ± 2.16 and 1.53 ± 2.18 mm in order. Conclusions: The medial meniscus can extrude 1.74 ± 1.84 mm normally while this amount was 1.26 ± 1.82 mm for the lateral meniscus. These measures commonly increased with the rising of knee flexion motion. Likewise, the posterior portion showed more extrusion than the anterior portion on both sides. These measures commonly increased with higher knee flexion. Access the CME test here and search by article title. [ABSTRACT FROM AUTHOR]

Background: Meniscus root tear is an uncommon but detrimental injury of the knee. Hoop stress is lost during meniscus root tear, which can lead to excessive tibiofemoral contact pressure and early development of osteoarthritis. Posterolateral meniscus root tears (PLRT) are more commonly associated with anterior cruciate ligament (ACL) tears. As the lateral compartment is less congruent than the medial compartment, it is more susceptible to a shearing force, which is increased in the ACL-deficient knee. In accordance with the compressive axial load, the increase in the tibial slope would generate a greater shearing force. The additional lateral compartment mobility caused by ACL tear should be reduced after ACL reconstruction (ACLR). However, there is a lack of evidence to conclude that ACLR can sufficiently limit the effect of large tibial slope (LTS) on the healing after PLRT repair. This study aimed to evaluate whether a steep LTS would be a risk factor for poorer clinical outcomes after PLRT repair concomitant with ACLR. Methods: In this retrospective study, a chart review was conducted to identify patients with concomitant unilateral primary ACLR and PLRT repair. Patients with a partial tear or healed tear were excluded. Postoperative MRI and clinical assessments were performed at a mean follow up of 35 months. MRI data was used to measure the LTS, medial tibial slope (MTS), coronal tibial slope (CTS), the lateral-to-medial slope difference (LTS-MTS) and meniscus healing and extrusion. Functional outcomes were evaluated by patient-reported outcomes (International Knee Documentation Committee [IKDC], Lysholm and Tegner scores) and KT-1000 arthrometer assessment. Interobserver reproducibility was assessed by two reviewers. Results: Twenty-five patients were identified for the analysis. Patients with larger LTS and larger LTS-MTS differences were shown to be correlated with poorer IKDC scores after surgery (R = -0.472, p = 0.017 and R = -0.429, p = 0.032, respectively). Herein, patients with LTS ≥ 6° or LTS-MTS ≥ 3° demonstrated poorer IKDC scores. Conclusion: A large LTS (≥ 6°) and a large difference of LTS-MTS (≥ 3°) were shown to be risk factors for poorer functional and radiological outcomes for PLRT repair in patients after ACLR. Clinically, closer monitoring and a more stringent rehabilitation plan for patients with LTS ≥ 6° or LTS-MTS ≥ 3° would be recommended. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the postoperative meniscal extrusion between all-inside suture (AIS) and trans-capsular suture (TCS) repair techniques., Methods: Thirteen patients (mean age, 19.4 years) underwent AIS repairs using only sutures (AIS group) for radial tears in the middle segment of the lateral meniscus (RTMLM), and seven patients (mean age, 20.3 years) underwent inside-out repairs among TCS (TCS group). For all cases, lateral (LE), anterior (AE) and posterior (PE) meniscal extrusions of the lateral meniscus were measured during preoperative and 3-, 12- and 24-week postoperative MRIs. Then, the change of each extrusion from preoperative to each postoperative period was calculated as ∆LE, ∆AE and ∆PE., Results: There was no significant difference between the AIS and TCS groups in the preoperative extrusions. As for postoperative extrusions, only ∆LEs in the AIS group was significantly smaller than those in the TCS group at all postoperative periods (-1.5 ± 1.7 vs. 0.9 ± 0.7 mm at 3-week, -0.9 ± 0.9 vs. 0.4 ± 0.9 mm at 12-week and -0.3 ± 1.0 vs. 0.6 ± 1.1 mm at 24-week postoperation). In ∆AEs and ∆PEs, at all three postoperative periods, there were no significant differences., Conclusion: Postoperative LE, AE and PE on MRIs after AIS and TCS repairs for RTMLM were investigated. Significantly smaller lateral extrusion was observed within 24 weeks after AIS repairs of RTMLM compared to TCS repairs, which could lead to stabilization of the repair site and prevent degenerative changes., Level of Evidence: Case-control study, retrospective comparative study, Level Ⅲ., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Journal of Experimental Orthopaedics published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Abstract Background Post-arthroscopic osteonecrosis of the knee (PAONK) is a rare condition. No studies have analyzed the relationship between the meniscus extrusion and PAONK. The purpose of this retrospective study is to test a hypothesis that the degree of the medial meniscus (MM) extrusion might be significantly greater in the knees with PAONK than in the matched control knees both before and after the meniscectomy. Methods Ten knees with PAONK were detected out of a total of 876 knees which had undergone arthroscopic partial meniscectomy of the MM. Ten matched control knees were randomly selected out of the remaining 866 knees without PAONK. The clinical data of these 20 patients were retrospectively collected from the medical records. To evaluate the location of the menisci on the joint line, Extrusion width and Inner width were defined on a coronal section of magnetic resonance imaging (MRI). The intra- and inter-rater reliability was evaluated by calculating the intra- and inter-class coefficients. Statistical comparisons between the 2 groups were made using the 3 non-parametric tests. Results Before the meniscectomy, the Extrusion width of the MM (mean 4.7 ± 1.4 mm) was significantly greater than that (3.0 ± 1.3 mm) in the Control group (P = 0.0195). In the MRI taken in a range from 3 to 50 weeks after the meniscectomy, the Extrusion width of the MM (5.9 ± 1.1 mm) in the PAONK group was significantly greater than that (3.4 ± 1.4 mm) in the Control group (P = 0.0009), and the Inner width of the MM (0.6 ± 1.7 mm) in the PAONK group was significantly less than that (3.9 ± 1.0 mm) in the Control group (P = 0.0001). Conclusion A significant relationship was found between the degree of the MM extrusion and the onset of PAONK. This study suggested that the extrusion of the MM is a potential predisposing factor for PAONK.

Purpose: The purpose of this study was to compare clinical and radiological outcomes of transtibial pullout technique and partial meniscectomy, and to establish prognostic factors in middle-aged patients with mild knee osteoarthritis. Methods: A comparative case–control analysis was conducted. 65 patients between 40 and 60 years of age were included into two groups: 30 patients who underwent transtibial pullout technique (group 1) and 35 patients who underwent partial meniscectomy (group 2). Mean follow-up was set at 27.2 months. Primary clinical outcomes included Knee injury and Osteoarthritis Outcome Score and Lysholm Knee Questionnare. Preoperative MRI and intraoperative arthroscopic findings were recorded. The correlation between these findings and patient-reported subjective outcome were assessed. Results: The transtibial pullout group exhibited significantly greater improvement in clinical outcomes. A univariate model revealed that the presence of preoperative meniscal extrusion, body mass index (> 30), osteochondral defect, and female gender were predictors of poor clinical outcome. Multivariate regression analysis showed meniscal extrusion and osteochondral defect as significant prognostic factors for both study groups. Conclusion: Medial meniscus root repair leads to significantly improved clinical outcomes compared to partial meniscectomy in middle-aged patients with mild knee osteoarthritis. Presence of meniscal extrusion, osteochondral defect, BMI > 30, and female gender were deemed as predictors of poor postoperative patient-reported outcome. Level of Evidence: III therapeutic case–control study. [ABSTRACT FROM AUTHOR]

The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics. [ABSTRACT FROM AUTHOR]

Background: Lateral meniscal oblique radial tears (LMORTs) affect joint and meniscal stability in anterior cruciate ligament (ACL)–deficient knees. Purpose: To determine the clinically relevant kinematics associated with the most common posterior horn LMORT lesion types, types 3 (LMORT3) and 4 (LMORT4), untreated versus arthroscopic repair versus partial meniscectomy in combination with ACL reconstruction (ACLR). Study: Controlled laboratory study. Methods: Sixteen cadaveric knees underwent robotic testing for anterior drawer and pivot-shift simulations at multiple knee flexion angles in ACL-intact and ACL-deficient states, followed by sequential testing of arthroscopic ACLR, LMORT3 lesion, LMORT3 repair, and partial meniscectomy (n = 8). The same testing sequence was performed for LMORT4 lesions (n = 8). Results: ACLR restored kinematics in ACL-deficient knees to intact levels for all metrics tested. For anterior drawer, ACLR + LMORT3 tear and partial meniscectomy resulted in significantly greater anterior translation compared with ACL-intact at all angles (P <.05) and compared with ACLR at 60° and 90° (P <.014). For pivot shift, compared with ACL-intact knees, ACLR + LMORT3 tear resulted in significantly more anterior translation at 15° (P =.041); and for ACLR + partial meniscectomy, at both 0° and 15° (P <.03). ACLR + LMORT4 tear and partial meniscectomy resulted in significantly greater anterior translation for anterior drawer (P <.04) and pivot-shift testing (P <.05) compared with intact and ACLR knees at all angles tested. ACLR + LMORT3 repair and ACLR + LMORT4 repair restored kinematics to ACLR and intact levels at all angles tested. ACLR + LMORT3 tear (P <.008) and both LMORT4 tear and partial meniscectomy (P <.05) resulted in increased meniscal extrusion compared with intact and ACLR statuses at all tested angles for anterior drawer and pivot shift, while repairs restored meniscal stability to ACLR and intact levels. Conclusion: Untreated LMORT tears increased anterior translation, pivot shift, and meniscal extrusion after ACLR, while partial meniscectomy further exacerbated these detrimental effects in this cadaveric model. In contrast, arthroscopic side-to-side repair of LMORT lesions effectively restored measured knee kinematics. Clinical Relevance: LMORT lesions are common with ACL tears and adversely affect joint stability and meniscal extrusion. This study highlights the importance of repair of LMORT 3 and 4 lesions at the time of ACLR. [ABSTRACT FROM AUTHOR]

Objective : To assess the association between morphological changes in the superficial medial collateral ligament and meniscal extrusion with medial meniscus posterior root tear. Materials and methods: From January 1, 2018, to December 31, 2019, 124 patients who underwent knee MRI within 90 days prior to knee surgery and whose medial meniscus surgically proved intact, with posterior root tear or posterior horn tear, were enrolled. Two radiologists who were blinded to the surgical results assessed the morphological changes in the superficial medial collateral ligament, including thickness, bowing angle, and presence of signal intensity alteration, and medial meniscus extrusion, according to the presence of tears in the posterior root of the medial meniscus or posterior horn of the medial meniscus using the chi-square test, one-way ANOVA, and Cohen's kappa test. Results: Thirty-six posterior root tears, 31 posterior horn tears, and 57 intact medial menisci were observed surgically. The mean values of thickness showed no significant differences among the three groups. The bowing angle was significantly higher in the posterior root tear than in the posterior horn tear (reader 1 = 0.001, reader 2 = 0.002) and normal meniscus groups (readers 1 and 2 < 0.001). The percentage of superficial medial collateral ligament signal intensity alteration and meniscal extrusion was highest in the group with posterior root of the medial meniscus tear (80.6% and 94.4%, respectively) and lowest in the group with normal medial meniscus (17.5% and 10.5%, respectively). Conclusion: Morphological changes in the superficial medial collateral ligament and meniscal extrusion were associated with medial meniscus posterior root tears. [ABSTRACT FROM AUTHOR]

Background: We recently analyzed the joint capsule adjacent to the medial meniscus and found that the perimeniscal joint capsule has collagen fiber orientation similar to that of circumferential meniscal fibers, potentially playing a role in preventing extrusion. Purpose: To analyze the meniscal extrusion prevention potential of the circumferential rim augmentation suture around the perimeniscal capsule in a rabbit root tear model and analyze the biomechanical function in a porcine cadaveric knee. Study Design: Controlled laboratory study. Methods: Rabbit medial meniscus root tear models were divided into 3 experimental groups: root tear, root tear and suture repair, and root tear and circumferential rim augmentation suture. As for the circumferential rim augmentation suture procedure, a suture was placed to circumscribe the outer rim of the medial meniscus and passed through bone tunnels located at the tibial insertion of each root. After 4 and 8 weeks, meniscal extrusion was analyzed by micro–computed tomography, gross morphology, and histologic analysis of the medial femoral cartilage. For biomechanical analysis, porcine knees were divided into groups similar to rabbit experiments. Tibiofemoral contact parameters were assessed using a pressure mapping sensor system after applying a load of 200 N on the knee joint. Results: The root tear and circumferential rim augmentation suture group showed less meniscal extrusion, less gap within the tear site, and less cartilage degeneration compared with other groups after 4 and 8 weeks of surgery in the rabbit root tear model. Biomechanical analysis showed the root tear and circumferential rim augmentation suture group had larger contact area and lower peak contact pressure compared with root tear and root tear and suture repair groups. Conclusion: The circumferential rim augmentation suture reduced the degree of meniscal extrusion while restoring meniscal function, potentially preventing progression of arthritis in a rabbit root tear model and porcine knee biomechanical analysis. Clinical Relevance: The circumferential rim augmentation suture may be a novel augmentation option during root tear treatment. [ABSTRACT FROM AUTHOR]

Background: Prospective evaluation of clinical outcomes after posterior meniscal root repair utilizing a transtibial pullout technique is limited, and factors that may contribute to outcomes are unclear. Hypothesis: It was hypothesized that there would be an overall significant improvement in outcomes after root repair and that differences in clinical outcomes would correlate with age, body mass index (BMI), sex, and meniscal extrusion. Study Design: Case-control study; Level of evidence, 3. Methods: Consecutive patients undergoing transtibial medial or lateral meniscal root repair were enrolled prospectively at 2 orthopaedic centers between March 2017 and January 2019. Pre- and postoperative magnetic resonance imaging (MRI) were obtained to assess for meniscal healing, quantification of extrusion, articular cartilage grade, and subchondral bone changes. Patient-reported outcomes including International Knee Documentation Committee (IKDC) scores, Tegner activity scale, and visual analog scale (VAS) for pain were collected preoperatively and 2 years postoperatively. Patients were then subdivided by clinical and demographic characteristics to determine factors associated with clinical outcomes. Results: Included were 45 patients (29 female, 16 male; mean age, 42.3 ± 12.9 years; mean BMI, 31.6 kg/m2) who underwent 47 meniscal root repairs (29 medial and 16 lateral; 2 had both). Significant improvements at 2-year follow-up were seen in IKDC score (41.1 vs 78.4; P <.001), Tegner activity level (3 vs 4; P <.001), and VAS pain (2.8 vs 0.7; P <.001). BMI, preoperative malalignment, cartilage status, and progressive meniscus extrusion (Δ = 0.7 mm) did not have a negative impact on IKDC and Tegner scores 2 years postoperatively. Age greater than or equal to 50 years and extrusion pre- and postoperatively were associated with decreased Tegner scores. Progressive meniscal extrusion was associated with a decreased overall improvement in Tegner scores. Conclusion: Transtibial root repair for medial and lateral posterior meniscal root tears demonstrated significantly improved clinical outcomes at 2 years postoperatively. Increased age, increased BMI, cartilage status, and meniscal extrusion did not have a negative impact on short-term functional outcomes (IKDC), but age greater than or equal to 50 years and extrusion negatively influenced patient activity level (Tegner). Registration: NCT03037242 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Abstract Background Meniscal extrusion results in loss of the ability to resist hoop strain and biomechanical overload on the joint articular surface. A centralization technique has been developed to overcome these problems. In this study, we analyzed the biomechanics of the extruded and centralized lateral meniscus (LM) in porcine knee joints at different flexion angles. Methods Porcine knee joints (n = 8) were set in the universal tester and each knee was tested under the following states: 1) intact; 2) extrusion—meniscal extrusion was created by resecting the posterior root of the LM and posterior synovial capsule; and 3) centralization—centralization was performed by two anchors inserted in the lateral tibial plateau. Deviation distance of the meniscus, contact pressure, and contact area in the anterior LM, middle LM, posterior LM, and the contact pressure of the tibial cartilage were evaluated with an axial compressive force of 200 N at knee flexion angles of 30°, 45°, 60°, and 90°. Results The deviation distance of LM significantly increased in extrusion but was restored to the intact status after centralization at all angles. Both the contact pressure and area significantly decreased in extrusion and were restored after centralization close to the intact status in the anterior and middle LM; in the posterior LM, however, decreased contact pressure and area were not restored after centralization. The contact pressure of the tibial cartilage increased significantly in extrusion but decreased close to the intact status after centralization. Conclusions This centralization procedure could reduce extrusion of the LM and restore the load-distributing function of the anterior-middle LM. However, the procedure itself could not restore hoop function in cases where the defect lies in the posterior LM.

Purpose: To systematically review and summarize the available literature on (1) postoperative healing rates, meniscal extrusion (ME) and clinical outcomes following lateral (LMPRR) versus medial (MMPRR) root repair and (2) potential correlations between residual ME and healing outcomes., Methods: A comprehensive literature search was conducted using the Scopus, PubMed and Embase databases. Clinical studies evaluating healing status on second-look arthroscopy and magnetic resonance imaging (MRI) after LMPRR and MMPRR were included. Study quality was assessed using the Methodological Index for Non-Randomized Studies criteria and the modified Coleman Methodology Score., Results: Twenty-three studies comprising 871 patients with LMPRR (n = 406) and MMPRR (n = 465) were included. Overall, 223 (54.9% of total) and 149 (32.04% of total) patients underwent second-look arthroscopy in the LMPRR and MMPRR groups, respectively. Complete root healing was observed in 190 (85.2%) patients in the LMPRR group versus 78 (52.3%) in the MMPRR group (p < 0.001). There were six (2.7%) failed repairs in the LMPRR group compared to 21 (14.09%) in the MMPRR group (p < 0.001). On postoperative MRI, 109 (75.7%) root repairs were healed in the LMPRR group compared to 192 (53.3%) in the MMPRR group (p < 0.001). Failure rates were lower after all-inside and transtibial pullout repairs in the LMPRR group but higher in the MMPRR group, with no significant mean difference between preoperative and postoperative ME in the MMPRR group (p = 0.95). Significantly better clinical outcomes were observed in the LMPRR group compared to the MMPRR group. A greater degree of postoperative ME was associated with lower healing rates (R = -0.78, p < 0.0005). Postoperative ME did not influence clinical outcomes (R = 0.28, p = 0.29)., Conclusions: Lateral meniscus posterior root repairs showed higher healing rates compared to MMPRR on both second-look arthroscopy and postoperative MRI. Meniscal extrusion decreased after LMPRR but not after MMPRR. Greater residual ME correlated inversely with healing rates, as more extrusion was associated with lower healing. Postoperative clinical improvement did not affect ME or healing status., Study Design: Systematic review of level III and IV studies., Level of Evidence: Level IV., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: To perform a systematic review and meta-analysis of the existing literature on meniscal centralisation procedures, analysing its impact on meniscal extrusion, joint biomechanics and clinical and radiological outcome measures., Methods: The Cochrane Controlled Register of Trials, PubMed (MEDLINE) and Embase were used to perform a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Biomechanical studies on healthy animal or human cadaveric knee joints that assessed meniscal extrusion or tibiofemoral contact mechanics (contact area and pressure) following centralization for meniscal pathologies were included. For clinical studies, those that prospectively or retrospectively assessed patient-reported outcome measures (PROMs), postoperative knee motion, complications and radiological extrusion following centralization for meniscal pathologies were included., Results: Fifteen studies were included in the analysis, comprising eight biomechanical, six clinical and one both. There were 92 knee specimens for biomechanical testing, of which 40 were human cadaveric and 52 porcine models. Biomechanical data revealed centralization to be commonly performed for posterior meniscal root tears and significantly reduced extrusion and contact pressure whilst improving contact area following a tear (p < 0.00001). Centralization restored extrusion to that of the native knee at all flexion angles described (0-90°, p = 0.25) and, compared to the torn state, brought tibiofemoral contact mechanics 3.2-5.0 times closer to the native state. Clinical data showed that 158 patients underwent centralization for extrusion. It improved postoperative Knee Injury and Osteoarthritis Outcome score (KOOS) (p = 0.006) and Lysholm scores (p < 0.00001) at 25.0 months, maintained extrusion reduction at 17.1 months (p < 0.00001) and preserved knee motion., Conclusion: Centralisation for various meniscal injuries associated with extrusion can reduce meniscal extrusion and improve joint biomechanics, along with clinical and radiological outcomes. Existing evidence is still scarce and exhibits a notable amount of methodological heterogeneity., Level of Evidence: Systematic review of Level IV evidence., (© 2024 The Author(s). Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Importance: The field of meniscal root preservation has undergone significant advancement over the past decades; however, the challenge remains to fully understand whether meniscal root repair can ultimately arrest or delay osteoarthritic changes., Objective: To assess longitudinal changes in articular cartilage, subchondral bone, and progression to meniscal extrusion (ME) using high-resolution magnetic resonance imaging (MRI)., Methods: Medial meniscus posterior root tear was surgically induced in 39 New Zealand white rabbits. Animals were randomly assigned into three experimental groups: partial meniscectomy after root tear (PM, n ​= ​13); root tear left in situ (CT, n ​= ​13); and transtibial root repair (RR, n ​= ​13). Contralateral limbs were used as healthy controls. High resolution 4.7 Tesla MRI of the knee joint was performed at baseline, after 2-, and 4-months of post-surgery. Cartilage thickness was calculated in medial and lateral compartments. In addition, the evaluation of ME, subchondral bone edema and healing potential after root repair were assessed too., Results: Progressive cartilage thinning, ME, and subchondral bone edema were evident in all 3 study groups after 4-months of follow-up. The mean cartilage thickness in the PM group was 0.53 ​mm (±0.050), 0.57 ​mm (±0.05) in the CT group, and 0.60 ​mm (±0.08) in the RR group. The PM group exhibited significantly higher cartilage loss when compared to the CT and RR groups (p ​< ​0.001). Moreover, progressive ME and subchondral bone edema were associated with a more severe cartilage loss at the final follow-up., Conclusion: Meniscal root repair did not halt but rather reduced the progression of osteoarthritis (OA). Degenerative changes worsened at a rapid rate in the PM group compared to the RR and CT groups. Early cartilage swelling, persistent subchondral edema, and progressive ME predicted a more severe progression to knee OA in the CT and RR groups., Level of Evidence: II., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Persistent knee pain in patients around the fifth decade of life is a frequent cause of attention in rehabilitation consultations. The most common cause of diagnosis is knee osteoarthritis, considering the existence of different degrees seen in simple radiographies. The advanced degrees present joint space reduction, osteophytosis and subchondral sclerosis; however, in the initial degrees, the findings are more subtle and sometimes nonexistent for conventional radiology. Clinical ultrasound has partly come to fill this «diagnostic gap», making it possible to detect meniscal extrusions and small osteophytes as signs of incipient osteoarthritis and to relate them as triggers of pain. In clinical practice we find a group of patients who, with little or no radiological alterations, present persistent and severe pain with medial predominance in most cases. These, until the appearance of the current evidence, were subsidiaries of meniscectomies. At this moment, when meniscectomies are not recommended, it is necessary to find a treatment for those cases in which conservative and non-ablative interventional treatment has failed. In this context, the possibility of using radiofrequency arises. Its use is widespread in the case of tricompartmental and advanced osteoarthritis. However, little data is available on its usefulness in cases of medial meniscal extrusion. It seems that thermal radiofrequency has greater effects than pulsed radiofrequency. We present a clinical case where thermal radiofrequency of the medial genicular nerves of the knee is proposed as a therapeutic alternative for chronic pain secondary to medial meniscal extrusion associated with incipient knee osteoarthritis, with the result of a decrease in pain (VAS 8 before treatment, VAS 1 after one year), subjective improvement of 80% and gait capacity., (Copyright © 2024 Sociedad Española de Rehabilitación y Medicina Física. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Lateral meniscal oblique radial tears (LMORT) occur frequently in conjunction with anterior cruciate ligament (ACL) disruption and are anatomically distinct from meniscus root tears. Hypothesis/Purpose: The purpose of this study was to characterize the effects of LMORT types 3 (LMORT3) and 4 (LMORT4) lesions on joint stability and meniscal extrusion in ACL-deficient knees. Our hypothesis was that both lesions would promote significant increases in anterior translation and meniscal extrusion, with the LMORT4 lesion having a greater effect. Study Design: Controlled laboratory study. Methods: Two matched pairs of cadaveric knees (n = 4) were used to optimize the testing sequence. Additional cadaveric knees with LMORT3 (n = 8) and LMORT4 (n = 8) lesions created after ACL transection underwent robotic kinematic testing for anterior drawer and pivot-shift simulations with associated ultrasound-measured meniscal extrusion at clinically relevant knee flexion angles. Results: Optimization testing showed no differences on the effect of LMORT4 lesions for anterior translation and lateral meniscal extrusion with ACL-intact versus ACL-deficient knees. ACL deficiency and LMORT3 and LMORT4 lesions with ACL deficiency were associated with significantly greater anterior translation compared with ACL-intact state for both anterior drawer and pivot-shift testing at all flexion angles (P <.001). ACL deficiency with either LMORT3 or LMORT4 lesion was associated with significantly greater anterior translation than was ACL deficiency only (P <.005) for anterior drawer testing at 90° of flexion. Meniscal extrusion was greater with LMORT3 and LMORT4 lesions compared with ACL deficiency only (P <.05) for anterior drawer at 60° of flexion and for pivot shift at 15° of flexion. The LMORT4 lesion demonstrated increased anterior translation for anterior drawer (P =.003) at 60° of flexion (12%) as well as for pivot shift at 15° of flexion (7%) and 30° of flexion (13%) (P <.005) compared with ACL deficiency only. Conclusion: In this cadaveric model, the addition of an LMORT3 or LMORT4 lesion increased anterior laxity for both the anterior drawer and the pivot shift when compared with an isolated ACL tear. Lateral meniscal extrusion was also exacerbated by these LMORT lesions. Clinical Relevance: LMORT lesions, distinct from meniscus root tears, occur frequently in conjunction with ACL tears. This study characterized the biomechanical consequences of LMORT3 and LMORT4 lesions on joint stability and meniscal function, highlighting the importance of diagnosing and treating LMORT lesions at the time of ACL reconstruction. [ABSTRACT FROM AUTHOR]

Purpose: The volume of medial meniscus (MM) extrusion at 10° and 90° knee flexions using three-dimensional (3D) magnetic resonance imaging (MRI) and assessed relevant clinical outcomes at 1-year follow-up were evaluated. Methods: Twenty-four patients who underwent MM posterior root repair were retrospectively reviewed. At 10° and 90° knee flexions, the meniscal extrusion distance and volume were measured using 3D meniscus models constructed by SYNAPSE VINCENT®. The correlation between Knee Injury and Osteoarthritis Outcome Score, Lysholm, International Knee Documentation Committee scores, Tegner activity, and pain visual analog scales and changes in MM extrusion were assessed. Results: No significant differences in the MM medial extrusion were observed between 10° and 90° knee flexions postoperatively. MM posterior extrusion (MMPE) decreased significantly at 10° and 90° knee flexions postoperatively. At 90° knee flexion, the meniscus volume at the intra-tibial surface increased at 3 and 12 months postoperatively. The MM extrusion volume increased slightly at 10° knee flexion; however, the volume decreased significantly at 90° knee flexion postoperatively. The change in MMPE significantly correlated with clinical scores. All 12-month clinical scores were significantly improved compared to preoperative scores. Conclusions: The progression of meniscus posterior extrusion and reduction of its volume at 90° knee flexion can be suppressed by MM posterior root repair. Postoperative clinical scores correlated with reductions of the posterior extrusion. Regarding clinical relevance, the dynamic stability of the meniscus can be maintained by MM posterior root repair, which is an effective therapeutic method for improving its clinical status. Level of evidence: Level IV. [ABSTRACT FROM AUTHOR]

Background: Meniscal extrusion, referred to as an external displacement of the meniscus, is a commonly encountered but often overlooked magnetic resonance imaging finding in the knee joint. Meniscal extrusion alters the biomechanical properties of the meniscus, leading to accelerated cartilage degeneration and early osteoarthritic changes. The literature contains discrepancies about meniscal extrusion on topics ranging from definition to diagnosis. This narrative review outlines the pathogenesis, natural history, diagnosis, and treatment of meniscal extrusion. Purpose: To review the current literature on meniscal extrusion, from pathogenesis to treatment, and to provide recommendations for future research. Study Design: Narrative review. Methods: A computer-based search of the PubMed, Ovid Medline, and Cochrane Library databases was used to perform a comprehensive literature review on meniscal extrusion. A total of 81 studies was ultimately included in the review. Results: The literature review highlighted the current ambiguity in definition, difficulty in clinical diagnosis, and low level of awareness of this condition. This review covers all aspects related to meniscal extrusion and identifies many of its lesser known aspects. Conclusion: In the current literature, meniscal extrusion remains a lesser known albeit common condition because of its relatively silent nature along with lack of knowledge among orthopaedic surgeons. Further studies are warranted to provide better understanding and management of this condition. [ABSTRACT FROM AUTHOR]

Background. Increased mechanical loading and pathological response of joint tissue to the abnormal mechanical stress can cause degradation of cartilage characteristic of knee osteoarthritis (OA). Despite osteoarthritis is risk factor for the development of meniscal lesions the mechanism of degenerative meniscal lesions is still unclear. Therefore, the aim of the study is to investigate the influence of medial compartment knee OA on the stress state and deformation of the medial meniscus. Methods. The finite element method was used to simulate the stance phase of the gait cycle. An intact knee model was prepared based on magnetic resonance scans of the left knee joint of a healthy volunteer. Degenerative changes in the medial knee OA model were simulated by nonuniform reduction in articular cartilage thickness in specific areas and by a decrease in the material parameters of cartilage and menisci. Two additional models were created to separately evaluate the effect of alterations in articular cartilage geometry and material parameters of the soft tissues on the results. A nonlinear dynamic analysis was performed for standardized knee loads applied to the tibia bone. Results. The maximum von Mises stress of 26.8 MPa was observed in the posterior part of the medial meniscus body in the OA model. The maximal hoop stress for the first peak of total force was 83% greater in the posterior horn and only 11% greater in the anterior horn of the medial meniscus in the OA model than in the intact model. The reduction in cartilage thickness caused an increase of 57% in medial translation of the medial meniscus body. A decrease in the compressive modulus of menisci resulted in a 2.5-fold greater reduction in the meniscal body width compared to the intact model. Conclusions. Higher hoop stress levels on the inner edge of the posterior part of the medial meniscus in the OA model than in the intact model are associated with a greater medial translation of the meniscus body and a greater reduction in its width. The considerable increase in hoop stresses shows that medial knee OA may contribute to the initiation of meniscal radial tears. [ABSTRACT FROM AUTHOR]

Background: Post-arthroscopic osteonecrosis of the knee (PAONK) is a rare condition. No studies have analyzed the relationship between the meniscus extrusion and PAONK. The purpose of this retrospective study is to test a hypothesis that the degree of the medial meniscus (MM) extrusion might be significantly greater in the knees with PAONK than in the matched control knees both before and after the meniscectomy.Methods: Ten knees with PAONK were detected out of a total of 876 knees which had undergone arthroscopic partial meniscectomy of the MM. Ten matched control knees were randomly selected out of the remaining 866 knees without PAONK. The clinical data of these 20 patients were retrospectively collected from the medical records. To evaluate the location of the menisci on the joint line, Extrusion width and Inner width were defined on a coronal section of magnetic resonance imaging (MRI). The intra- and inter-rater reliability was evaluated by calculating the intra- and inter-class coefficients. Statistical comparisons between the 2 groups were made using the 3 non-parametric tests.Results: Before the meniscectomy, the Extrusion width of the MM (mean 4.7 ± 1.4 mm) was significantly greater than that (3.0 ± 1.3 mm) in the Control group (P = 0.0195). In the MRI taken in a range from 3 to 50 weeks after the meniscectomy, the Extrusion width of the MM (5.9 ± 1.1 mm) in the PAONK group was significantly greater than that (3.4 ± 1.4 mm) in the Control group (P = 0.0009), and the Inner width of the MM (0.6 ± 1.7 mm) in the PAONK group was significantly less than that (3.9 ± 1.0 mm) in the Control group (P = 0.0001).Conclusion: A significant relationship was found between the degree of the MM extrusion and the onset of PAONK. This study suggested that the extrusion of the MM is a potential predisposing factor for PAONK. [ABSTRACT FROM AUTHOR]