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Objective: To investigate application of the Codamotion 2CX1 three-dimensional dynamic joint motion capture system to analyze the kinematic characteristics of patients with different degrees of meniscus injury., Methods: From December 2020 to June 2022, 135 patients with meniscus injury and recruited normal people were collected, including 82 males and 53 females, aged 14 to 29 years old, with disease duration of 1 to 3 months. Combined with clinical symptoms and MRI examination, the diagnosis of meniscus injury was confirmed, and the patients were divided into stages, including 37 cases of grade 0(normal), 30 cases of gradeⅠ, 33 cases of gradeⅡ, 35 cases of grade Ⅲ according to Stoller grading standard. Subjects in each group were tested walking by using Codamotion 2CX1 three-dimensional dynamic joint motion capture system. Quantitative indexes of walking and kinematics were collected, including knee flexion and extension, internal and external rotation and internal and external turning, and their kinematics were analyzed., Results: In the distribution of knee flexion/extension, there were significant differences in maximum knee flexion, minimum knee extension and knee flexion and extension range among 4 groups( P <0.05). In the distribution of internal/external rotation of knee joint, there were significant differences in the range of internal rotation and rotation of knee joint among 4 groups( P <0.05). In the distribution of internal/external turning of knee joint, there were significant differences in the range of internal and external turning of knee joint among 4 groups( P <0.05). The clinical stage progression was positively correlated with the range of motion of knee extension, external rotation, internal and external turning and turning range( P <0.05). It was negatively correlated with knee flexion, internal rotation, flexion extension and rotation range( P <0.05). The internal and external rotation angles of knee joint could be used as independent factors influencing the clinical stage of meniscus injury ( P =0.006, 0.019<0.05)., Conclusion: The knee movement of patients with meniscus injury has obvious changes, and the changes are different under different clinical stages. Gait analysis provides a reliable basis for the kinematic analysis of meniscus injury, helps to better understand the kinematic indexes of joints, and provides a reliable auxiliary diagnosis and treatment plan, which provides a new direction for the follow-up medical research.

Background: Visual impairment can cause balance problems. Therefore, visual impairment caused by an increase in corneal deviations can lead to sudden and unstable loads in the lower extremities. We aimed to investigate the possible relationship between low-energy meniscal injuries and corneal structural measures., Methods: This prospective, observational study included individuals aged between 18-40 years with a normal body-mass index. The study group consisted of 54 patients with grade 2 or 3 meniscus injuries after low-energy activity. The control group consisted of 54 healthy individuals without any complaints in the knee joint. The corneal parameters of all participants were evaluated with a Scheimpflug corneal topography and specular microscopy device. Simulated keratometry (SimK), minimum central corneal thickness (MCCT), cylindrical diopter (ClyD), corneal volume (CVol) spheric aberrations (SphAbb), high-order aberration (HOA), coma values, and endothelial parameters were recorded., Results: The research and control groups were similar in terms of age, body mass index, and gender distribution. There was no significant difference between the groups in the corneal SimK and CylD, parameters. However, HOA, Coma, SphAbb, and cell variability (Cv) values were significantly higher in the study group, and contrarily MCCT, CVol, and endothelial count (Cd) values were significantly lower., Conclusions: Our findings suggest that individuals with relatively lower MCCT values tend to develop meniscal damage after low-energy activity. Hence, the loss of corneal strength in these patients may be a sign of possible weakness in the meniscus. The HOA value above 0.26, the coma value above 0.16, and the SphAbb value above 0.1 may significantly increase the possible meniscus injury., (© 2024. The Author(s).)

Purpose: To evaluate the changes in contact characteristics of the tibiofemoral joint resulting from a meniscal ramp lesion in the medial meniscus., Methods: Twelve cadaveric knees (six matched pairs) were subjected to a 600 N axial load using a custom testing jig, which allowed for knee positioning at 0°, 45°, and 90° of flexion without other constraints. The knees were randomly assigned to either a ramp lesion group (n = 6) or a posterior root lesion group (n = 6). Four testing conditions were examined: (1) intact, (2) isolated ramp lesion, (3) isolated posterior root tear of the medial meniscus, and (4) combined ramp lesion and posterior root tear of the medial meniscus. Contact characteristics were evaluated using a flexible pressure sensor, the I-Scan System., Results: Peak contact pressure in isolated ramp lesions (4.15 ± 0.98 MPa, P = 0.206) showed non-significant increases compared to the intact condition (3.86 ± 1.32 MPa). Peak contact pressure in isolated posterior root tears (4.58 ± 1.70 MPa, P = 0.040) and, combined ramp and posterior root lesions (4.67 ± 1.47 MPa, P = 0.003) were significantly higher than that in the intact condition. The knee flexion position significantly affected the medial tibiofemoral joint's contact area, contact pressure, and peak contact pressure (P < 0.001 for all)., Conclusion: Isolated ramp lesions did not significantly impact force transmission, contact area, or contact pressure. In contrast, isolated root lesions and combined ramp and posterior root tears of the medial meniscus significantly intensified the changes in contact characteristics in the medial tibiofemoral joint compared to the intact condition., Level of Evidence: Level III., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Background: The effects of anterior cruciate ligament (ACL) reconstruction on postoperative gait biomechanics remain controversial, and the influence of meniscus pathology on pre- and post-ACL reconstruction biomechanical changes has not yet been studied. Here, we aimed to clarify the difference in knee joint moment between pre- and post-ACL reconstruction conditions in subjects with and without meniscal pathology., Methods: Twenty-four subjects with unilateral ACL reconstruction injuries participated in this study. A total of 13 of the subjects had concomitant meniscus injuries. Gait analysis was performed preoperatively and at 11 months postoperatively. Three-dimensional knee joint angles and moments were calculated based on motion-capture data. The total joint moment and contribution of individual moments during the stance phase were assessed. For statistical analysis, we compared pre- and postoperative alterations, and differences were assessed in subjects with and without meniscal pathology., Results: Tibial rotation excursion was lower in subjects with meniscal pathology than in those with intact menisci postoperatively. An significant increase in the contribution of the knee flexion moment and a significant decrease in the contribution of the knee adduction moment postoperatively were observed in subjects with intact menisci., Conclusions: Patients with ACL injury showed different postoperative alterations in joint moments depending on the concomitant meniscal injury., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: The purpose of this study was to determine how variations in lower limb alignment affect tibiofemoral joint contact biomechanics in the setting of medial meniscus posterior root tear (MMPRT) and associated root repair., Methods: A finite-element model of an intact knee joint was developed. Limb alignments ranging from 4° valgus to 8° varus were simulated under a 1,000 N compression load applied to the femoral head. For the intact, MMPRT, and root repair conditions, the peak contact pressure (PCP), total contact area, mean and maximum local contact pressure (LCP) elevation, and total area of LCP elevation of the medial tibiofemoral compartment were quantified., Results: The PCP and total contact area of the medial compartment in the intact knee increased from 2.43 MPa and 361 mm 2 at 4° valgus to 9.09 MPa and 508 mm 2 at 8° of varus. Compared with the intact state, in the MMPRT condition, medial compartment PCP was greater and the total contact area smaller for all alignment conditions. Root repair roughly restored PCPs in the medial compartment; however, this ability was compromised in knees with increasing varus alignment. Specifically, elevations in PCP relative to the intact state increased with increasing varus, as did the total contact area with LCP elevation. After root repair, medial compartment PCP remained elevated above the intact state at all degrees tested, ranging from 0.05 MPa at 4° valgus to 0.27 MPa at 8° of varus, with overall PCP values increasing from 2.48 to 9.09 MPa. For varus alignment greater than 4°, root repair failed to reduce the total contact area with LCP elevation relative to the MMPRT state., Discussion: Greater PCPs and areas of LCP elevation in varus knees may reduce the clinical effectiveness of root repair in delaying or preventing the development of tibiofemoral osteoarthritis., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

Background: Rupture of the knee menisci is a common injury that can have implications for other conditions, such as osteoarthritis. The fracture toughness of soft tissue (J c ) is a mechanical property that characterizes its resistance to tear extension. To date, J c of the meniscus has not been quantified., Methods: Cyclic tensile tests were conducted on meniscus samples to determine J c and explore its characteristics. Initially, the study investigated the impact of an initial notch on the ultimate tensile stress. This allowed for an understanding of how the presence of a notch affects its structural integrity. Subsequently, J c was measured in both the radial and circumferential directions to assess its loading direction dependency. Furthermore, the study assessed the effect of anatomical location by comparing samples collected from the femoral and tibial layers., Results: Defect tolerance of the meniscus is influenced by the loading direction. In the circumferential direction, the presence of an initial notch did not affect the ultimate stress, and no crack expansion was observed. In radial samples with a notch length of 40% or more of the total width, crack propagation occurred, leading to a decrease in the ultimate stress (p< 0.01). Additionally, J c was found to be higher in the femoral layer compared to the tibial layer (p= 0.017)., Conclusion: The study also examined the failure patterns of the meniscus to enhance our understanding of its pathology. These insights contribute to a better comprehension of meniscus injuries and can aid in the development of more effective treatment strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: An isokinetic moment curve (IMC) pattern-damaged structure prediction model may be of considerable value in assisting the diagnosis of knee injuries in clinical scenarios. This study aimed to explore the association between irregular IMC patterns and specific structural damages in the knee, including anterior cruciate ligament (ACL) rupture, meniscus (MS) injury, and patellofemoral joint (PFJ) lesions, and to develop an IMC pattern-damaged structure prediction model., Methods: A total of 94 subjects were enrolled in this study and underwent isokinetic testing of the knee joint (5 consecutive flexion-extension movements within the range of motion of 90°-10°, 60°/s). Qualitative analysis of the IMCs for all subjects was completed by two blinded examiners. A multinomial logistic regression analysis was used to investigate whether a specific abnormal curve pattern was associated with specific knee structural injuries and to test the predictive effectiveness of IMC patterns for specific structural damage in the knee., Results: The results of the multinomial logistic regression revealed a significant association between the irregular IMC patterns of the knee extensors and specific structural damages ("Valley" - ACL, PFJ, and ACL + MS, "Drop" - ACL, and ACL + MS, "Shaking" - ACL, MS, PFJ, and ACL + MS). The accuracy and Macro-averaged F1 score of the predicting model were 56.1% and 0.426, respectively., Conclusion: The associations between irregular IMC patterns and specific knee structural injuries were identified. However, the accuracy and Macro-averaged F 1 score of the established predictive model indicated its relatively low predictive efficacy. For the development of a more accurate predictive model, it may be essential to incorporate angle-specific and/or speed-specific analyses of qualitative and quantitative data in isokinetic testing. Furthermore, the utilization of artificial intelligence image recognition technology may prove beneficial for analyzing large datasets in the future., (© 2024. The Author(s).)

Objective: To identify and summarize literature related to the association between mechanical symptoms (catching and locking of the knee), the presence of meniscal tear, and outcomes after arthroscopic surgery., Design: We searched PubMed and hand-searched reference lists for relevant articles and selected 38 for analysis., Results: Mechanical symptoms appear to have modest sensitivity (ranging 0.32-0.69), specificity (ranging 0.45-0.74) and positive predictive value (ranging 0.75-0.81) for meniscal tear. There is also very little evidence to suggest that those with mechanical symptoms experience better outcomes after arthroscopic surgery., Conclusion: Our examination of the literature does not support the hypothesis that mechanical symptoms are related to the presence of meniscal tear or portend better outcomes after arthroscopic surgery., (Copyright © 2021 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Meniscal allograft transplantation provides treatment options for patients with a meniscus-deficient knee with lifestyle-limiting symptoms in the absence of advanced degenerative changes. Meniscal transplantation helps to restore the native biomechanics of the involved knee, which may provide chondroprotective effects and restoring additional knee stability. Improvements in pain, function, and activity level have been seen in appropriately selected patients undergoing transplantation. Although various surgical implantation options exist, the majority focus on reproducing native attachments of the meniscal roots to allow near normal mechanics. Although meniscal transplantation may serve as a salvage procedure for symptomatic patients with a meniscus-deficient knee, it may prevent or delay the necessity of a more invasive arthroplasty procedure., Competing Interests: Disclosure: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Posterior cruciate ligament (PCL) injuries commonly occur in association with participation in sporting or recreational activities or due to a direct trauma. Cartilage and meniscal lesions are prevalent in PCL-injured knees with increasing likelihood and severity based on extent and duration of trauma to the knee. As such, comprehensive diagnostics should be performed to ascertain all related pathology, and patients should be thoroughly educated regarding treatment options, likely sequelae including posttraumatic osteoarthritis, and associated outcomes. Treatments should address the joint as an organ, ensuring stability, alignment, and functional tissue restoration are optimized by the most efficient and effective means possible. Compliance with patient- and procedure-specific postoperative management protocols is critical for optimizing successful outcomes for these complex cases. The objectives of this review article are to highlight the likelihood and importance of osteochondral and meniscal pathology in the PCL-injured knee, and to provide the best current evidence regarding comprehensive evaluation and management for PCL-injured knees with cartilage and/or meniscal comorbidities., Competing Interests: J.P.S. reports grants and personal fees from Arthrex, Inc., grants from DePuy Synthes, other from Journal of Knee Surgery, grants from National Institutes of Health (NIAMS & NICHD), personal fees and other from Thieme, grants from U.S. Department of Defense, other from AO Foundation, other from American Orthopaedic Association, other from AO North America, grants from Coulter Foundation, other from Mid-America Orthopaedic Association, personal fees from Orthopedic Designs North America, personal fees from Smith & Nephew, outside the submitted work. J.L.C. reports grants and personal fees from Arthrex, Inc., personal fees from AthleteIQ, grants from ConforMIS, personal fees from CONMED Linvatec, grants from Coulter Foundation, grants from DePuy Synthes, grants and personal fees from Eli Lilly, other from Journal of Knee Surgery, grants from Merial, other from Midwest Transplant Network, grants, personal fees and other from Musculoskeletal Transplant Foundation, grants from National Institutes of Health (NIAMS and NICHD), grants from Purina, grants from Sites Medical, personal fees and other from Thieme, grants from TissueGen Inc, personal fees from Trupanion, grants from U.S. Department of Defense, grants from Zimmer-Biomet, outside the submitted work., (Thieme. All rights reserved.)

Injury to the meniscus is common and frequently leads to the development of post-traumatic osteoarthritis (PTOA). Many times meniscus injuries occur coincident with anterior cruciate ligament (ACL) injuries and lead to a bloody joint effusion. Hemarthrosis, or bleeding into the joint, has been implicated in degeneration of joint tissues. The goal of this review paper is to understand the pathophysiology of blood-induced joint damage, the possible effects of blood on meniscus tissue, and the implications for current meniscus repair techniques that involve the introduction of blood-derived products into the joint. In this review, we illustrate the similarities in the pathophysiology of joint damage due to hemophilic arthropathy (HA) and osteoarthritis (OA). Although numerous studies have revealed the harmful effects of blood on cartilage and synovium, there is currently a gap in knowledge regarding the effects of hemarthrosis on meniscus tissue homeostasis, healing, and the development of PTOA following meniscus injury. Given that many meniscus repair techniques utilize blood-derived and marrow-derived products, it is essential to understand the effects of these factors on meniscus tissue and the whole joint organ to develop improved strategies to promote meniscus tissue repair and prevent PTOA development., (Copyright © 2020 Osteoarthritis Research Society International. All rights reserved.)

Purpose: To evaluate the results of the remodified Mason-Allen suture technique concomitant with high tibial osteotomy (HTO) for medial meniscal posterior root tears (MMPRTs). The hypothesis was that this procedure would improve clinical results, prevent progression of knee osteoarthritis and increase the healing rate of the repaired root., Methods: Total 17 patients of mean 51.5 ± 4.4 years who were underwent this combined procedure for MMPRT completed this study. Lysholm and Hospital for Special Surgery (HSS) scores, Kellgren-Lawrence (KL) grade reflecting osteoarthritis progression were evaluated preoperatively and at the last follow-up. Medial meniscus extrusion (MME) was measured on magnetic resonance imaging preoperatively and at mean 26.1 ± 2.3 months postoperatively. Second-look arthroscopy was performed at mean 25.1 ± 5.3 months postoperatively. The healing status of the repaired root was classified as complete, partial and failed healing. The Outerbridge (OB) grade of the medial femoral condyle (MFC) was compared between index surgery and second-look arthroscopy., Results: Mean follow-up duration was 66.4 ± 6.5 months. Mean Lysholm and HSS mean scores improved significantly from preoperatively to the last follow-up: Lysholm: 56.9 ± 5.4 to 83.5 ± 6.0 (P < 0.001); HSS: 56.1 ± 6.0 to 81.7 ± 7.7 (P < 0.001). The mean mechanical alignment of the lower extremity was corrected from varus to the neutral range at the last follow-up. The preoperative KL grade was not significantly different from the KL grade at the last follow-up (P = 0.071). On MRI, mean MME increased from 3.0 ± 0.7 mm to 3.1 ± 0.7 mm (P = 0.046). Second-look arthroscopy showed 64.7% complete, 29.4% partial and 5.9% failed healing of the repaired root. The initial OB grade of the MFC showed no progression (P = 0.103)., Conclusions: The remodified Mason-Allen suture technique concomitant with HTO for MMPRTs significantly improved clinical outcomes and suppressed OA progression at 66.4 months. However, this procedure produced limited complete healing of the repaired roots in 64.7% of patients., Level of Evidence: IV.

Introduction: Early recognition of potential predictors on the success of conservative treatment of anterior cruciate ligament (ACL) is important, as appropriate treatment can be applied to each individual patient. The goal of this study is to assess the patient demographic and radiological parameters that predict coping with ACL injuries., Methods: All patients presenting with a complete ACL injury between 2014 and 2018 at our clinic were included. The role of patient demographics (age, gender, activity level, meniscus injury and time from injury to clinic), and ACL tear location, bone bruises, tibial slope, and anterolateral ligament (ALL) injury were assessed on the success of conservative treatment using univariate and multivariate analyses., Results: Sixty-five patients (32%) were copers and 141 (68%) were non-copers. Univariate analysis showed that copers were significantly older (40 vs. 27 years, P < 0.001), had lower preinjury activity level (Tegner 5.7 vs. 6.5, P < 0.001) and less often lateral meniscus tears (16% vs. 5%, P = 0.019) but not medial meniscus tears (17% vs. 14%, P = 0.609) than non-copers. Multivariate analysis revealed that increasing age (P < 0.001), Tegner level ≤ 6 (P = 0.003) and no meniscus injury (P = 0.045) were independent predictors of coping with ACL deficiency., Conclusions: Older age, participation in lower activity sports levels and absence of meniscus injury were predictive of coping with ACL deficiency, whereas there was no such role for tear location, tibial slope, lateral bone bruise presence, ALL injury or gender. These findings might help to identify potential copers and guide surgeons early in the optimal treatment for patients with ACL injury., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The degeneration of radial tie fibres of the central meniscal layer, and thinning of its lamellar layer results in increased intensity signals on magnetic resonance imaging, making it difficult to differentiate from true meniscal tear. This study aimed to assess the rate of encountered MRI grades 1 and 2 intrasubstance meniscal changes, and to set guidelines to report these changes based on predicted clinical outcome. A systematic review approach was employed using search engines, libraries, and databases (Google Scholar, ERIC, PubMed, and Medline) to search for scholarly sources on meniscal lesions and their significance in MRI published between 1 January 2000 and 30 June 2019. It retrieved 2750 abstracts, out of which 2738 were excluded and 13 studies meeting inclusion criteria were meta-analysed. It found an association between intrasubstances meniscal changes and outcomes. It resulted that intrasubstance meniscal changes were preservable through the protective functioning of the meniscus. Other than weight gain, no other significant risk factor of developing true meniscal tears later in life was found. It is important to examine intrasubstance meniscal change when patients suffer from mechanical meniscal symptoms especially in old age.

Purpose: Although several factors have been considered to be associated with pivot shift test grade in ACL injured patients, a conclusion regarding which factors contribute to the pivot shift test grade has not been reached. The purpose of this study was to identify factors associated with preoperative pivot shift test grade., Methods: Three hundred and sixty-six consecutive patients who underwent ACL reconstruction in our hospital were enrolled in the study. Patients were divided into two groups on the basis of preoperative pivot shift test grade (Mild: grade 0-3, Severe: grade 4-6). First, 13 independent variables (age, gender, period from injury to surgery, hyperextension, KT measurement, contralateral side pivot shift test grade, medial and lateral tibial slope, lateral condyle length, lateral condyle height, distal femoral condyle offset, medial and lateral meniscus tear) were analyzed by one-way ANOVA and Chi-squared test. Binary Logistic regression was then performed based on the results of univariate analyses (independent variables of p < 0.2 were included)., Results: Hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and KT measurement were identified as risk factors for preoperative pivot shift grade via logistic regression analysis., Conclusion: The current study revealed that hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and anterior instability were associated with preoperative pivot shift grade. Patients with above factors that cannot be modified during surgery may need special consideration when ACL reconstruction is performed, as greater preoperative pivot shift has been proven to be a risk factor for residual pivot shift after ACL reconstruction., Level of Evidence: III.

Purpose: To compare the effect of the lateral meniscus (LM) complete radial tear at different tear sites on the load distribution and transmission functions., Methods: A compressive load of 300 N was applied to the intact porcine knees (n = 30) at 15°, 30°, 60°, 90°, and 120° of flexion. The LM complete radial tears were created at the middle portion (group M), the posterior portion (group P), or the posterior root (group R) (n = 10, each group), and the same loading procedure was followed. Finally, the recorded three-dimensional paths were reproduced on the LM-removed knees. The peak contact pressure (contact area) in the lateral compartment and the calculated in situ force of the LM under the principle of superposition were compared among the four groups (intact, group M, group P, and group R)., Results: At all the flexion angles, the peak contact pressure (contact area) was significantly higher (lower) after creating the LM complete radial tear as compared to that in the intact state (p < 0.01). At 120° of flexion, group R represented the highest peak contact pressure (lowest contact area), followed by group P and group M (p < 0.05). The results of the in situ force carried by the LM were similar to those of the tibiofemoral contact mechanics., Conclusion: The detrimental effect of the LM complete radial tear on the load distribution and transmission functions was greatest in the posterior root tear, followed by the posterior portion tear and the middle portion tear in the deep-flexed position. Complete radial tars of the meniscus, especially at the posterior root, should be repaired to restore the biomechanical function.

Objectives: The aim of this study was to evaluate clinical and functional outcomes following the arthroscopic medial meniscal repair., Patients and Methods: A total of 50 patients (42 males, 8 females; mean age: 32.9±7.6 years; range, 17 to 48 years) who underwent arthroscopic repair for longitudinal and bucket-handle medial meniscal tears between March 2005 and October 2011 were retrospectively evaluated. The patients were divided into two groups as those having a longitudinal tear (patient group, n=31) and having a bucket-handle tear (control group, n=19). Preoperative and final follow-up functional outcomes were evaluated using the Lysholm Knee Score (LKS), International Knee Documentation Committee (IKDC) score, Tegner Activity Scale (TAS) score, and Knee Injury and Osteoarthritis Outcome Score (KOOS)., Results: The mean follow-up was 61.7±22.8 (range, 36 to 110) months. The mean preoperative LKS, IKDC score, TAS, and KOOS scores were significantly improved at the final postoperative follow-up (p<0.05). There was no significant difference in functional outcome scores between longitudinal and bucket-handle repairs (p>0.05), and isolated repairs and concomitant meniscal repair and anterior cruciate ligament reconstruction (p>0.05)., Conclusion: Arthroscopic meniscal repair provides similar mid-term functional and clinical outcomes for longitudinal and bucket-handle medial meniscal tears. Concomitant meniscal repair does not seem to affect meniscal healing.

Objective: To siscuss the clinical significance of the early diagnosis of knee varus and knee osteoarthritis with the combination of negative position and non-negative position and radiography., Methods: One hundred and eighty patients whose femorotibial angles <182° (genu varus positive) measured by X-ray at the weight-bearing position and femorotibial angles ≥182° (genu varus negative) measured by X-ray at the non-weight-bearing position were selected as the sample group from those patients who received knee joint Magnetic resonance imaging (MRI) examination from July 2015 to July 2017. One hundred and eighty patients whose femorotibial angles ≥182° (genu varus negative) measured at both the weight-bearing position and the non-weight-bearing position were selected as the control group. Femorotibial angles of both groups were respectively measured, to respectively compare and analyze the effect of non-weight-bearing false-negative genu varus on the occurrence and severity of injury of medial meniscus and femorotibial articular cartilage. The two groups of patients had no previous history of knee surgery, and no lower limb fracture, inflammation, tumor, metabolic bone disease, or congenital disease., Results: The weight-bearing tibiofemoral angles of the non-weight-bearing false-negative genu varus group and the negative genu varus group (180.998° ± 0.589°) were lower than the non-weight-bearing tibiofemoral angles (182.501° ± 0.290°), and they were positively correlated (t = -15.048, P < 0.01). The non-weight-bearing knee varus medial meniscus incidence of false- negative group. Medial meniscus injury that occurred in the sample group were 86.7% (156/180) in the anterior horn, 91.7% (165/180) in the body, 88.3% (159/180) in the posterior horn. Medial meniscus injury that occurred in the control group were 46.7% (84 /180) in the anterior horn, 40.6.3% (73/180) in the body, 43.3% (78/180) in the posterior horn. The incidence of degenerative groups, the differences were statistically significant. The incidence and severity of injury were as follows: medial meniscus anterior horn (χ 2 = 41.966, P = 0.000), body (χ 2 = 104.94, P = 0.000), posterior horn (χ 2 = 81.025, P = 0.000). The incidence and severity of medial meniscus injury in the non-weight-bearing knee varus false negative group was higher than in the control group. The non-weight-bearing knee varus false-negative group medial tibiofemoral articular cartilage degeneration rate was 95.0% (171/180); in the control group, medial tibiofemoral articular cartilage degeneration was 65.1% (117/180). Two medial tibiofemoral articular cartilage degeneration incidence were statistically significant. The incidence and severity of injury were as follows: medial tibiofemoral articular cartilage (χ 2 = 50.625, P = 0.000). The incidence and severity of medial tibiofemoral articular cartilage injury in the non-weight-bearing knee varus false negative group was higher than in the control group., Conclusion: The combined weight-bearing position and non-weight-bearing position imaging examination for diagnosing the non-weight-bearing false-negative genu varus patients at an early date is of significant importance to the early diagnosis and treatment of knee osteoarthritis., (© 2020 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

The meniscus plays a central load-bearing role in the knee joint. Unfortunately, meniscus injury is common and can lead to joint degeneration and osteoarthritis (OA). In small animal models, progressive degenerative changes occur with the unloading of the meniscus via destabilization of the medial meniscus (DMM). However, few large animal models of DMM exist and the joint-wide initiation of the disease has not yet been defined in these models. Thus, the goal of this study is to develop and validate a large animal model of surgically induced DMM and to use multimodal (mechanical, histological, and magnetic resonance imaging) and multiscale (joint to tissue level) quantitative measures to evaluate degeneration in both the meniscus and cartilage. DMM was achieved using an arthroscopic approach in 13 Yucatan minipigs. One month after DMM, joint contact area decreased and peak pressure increased, indicating altered load transmission as a result of meniscus destabilization. By 3 months, the joint had adapted to the injury and load transmission patterns were restored to baseline, likely due to the formation and maturation of a fibrovascular scar at the anterior aspect of the meniscus. Despite this, we found a decrease in the indentation modulus of the tibial cartilage and an increase in cartilage histopathology scores at 1 month compared to sham-operated animals; these deleterious changes persisted through 3 months. Over this same time course, meniscus remodeling was evident through decreased proteoglycan staining in DMM compared to sham menisci at both 1 and 3 months. These findings support that arthroscopic DMM results in joint degeneration in the Yucatan minipig and provide a new large animal testbed in which to evaluate therapeutics and interventions to treat post-traumatic OA that originates from a meniscal injury., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Purpose: To investigate changes in meniscal extrusion during knee flexion before and after pullout fixation for medial meniscus posterior root tear (MMPRT) and determine whether these changes correlate with articular cartilage degeneration and short-term clinical outcomes., Methods: Twenty-two patients (mean age 58.4 ± 8.2 years) diagnosed with type II MMPRT underwent open magnetic resonance imaging preoperatively, 3 months after transtibial fixation and at 12 months after surgery, when second-look arthroscopy was also performed. The medial meniscus medial extrusion (MMME) and the medial meniscus posterior extrusion (MMPE) were measured at knee 10° and 90° flexion at which medial meniscus (MM) posterior translation was also calculated. Articular cartilage degeneration was assessed using International Cartilage Research Society grade at primary surgery and second-look arthroscopy. Clinical evaluations included Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee subjective knee evaluation form, Lysholm score, Tegner activity level scale, and pain visual analogue scale., Results: MMPE at 10° knee flexion was higher 12 months postoperatively than preoperatively (4.8 ± 1.5 vs. 3.5 ± 1.2, p = 0.01). MMPE at 90° knee flexion and MM posterior translation were smaller 12 months postoperatively than preoperatively (3.5 ± 1.1 vs. 4.6 ± 1.3, 7.2 ± 1.7 vs. 8.9 ± 2.0, p < 0.01). Articular cartilage degeneration of medial femoral condyle correlated with MMME in knee extension (r = 0.5, p = 0.04). All clinical scores significantly improved 12 months postoperatively. However, correlations of all clinical scores against decreased MMPE and increased MMME were not detected., Conclusions: MMPRT transtibial fixation suppressed the progression of MMPE and cartilage degeneration and progressed MMME minimally in knee flexion position at 1 year. However, in the knee extension position, MMME progressed and correlated with cartilage degeneration of medial femoral condyle. MMPRT transtibial fixation contributes to the dynamic stability of the MM in the knee flexion position., Level of Evidence: IV.

Purpose: To clarify the effect of longitudinal tears of the medial meniscus on the in situ meniscus force and the tibiofemoral relationship under axial load., Methods: Twenty-one intact porcine knees were mounted on a 6-degrees of freedom robotic system, and the force and three-dimensional path of the knee joints were recorded during three cycles under a 250-N axial load at 30°, 60°, 90° and 120° of knee flexion. They were divided into three groups of seven knees with longitudinal tears in the middle to the posterior segment of the medial meniscus based on the tear site: rim, outer one-third and inner one-third of the meniscal body. After creating tears, the same tests were performed. Finally, all paths were reproduced after total medial meniscectomy, and the in situ force of the medial meniscus was calculated based on the principle of superposition., Results: With a longitudinal tear, the in situ force of the medial meniscus was significantly decreased at 60°, 90° and 120° of knee flexion, regardless of the tear site. The decrement was greater with a tear in the meniscal body than a tear in the rim. A longitudinal tear in the meniscal body caused a significantly greater tibial varus rotation than a tear in the rim at all flexion angles., Conclusion: Longitudinal tears significantly decreased the in situ force of the medial meniscus. Tears in the meniscal body caused a larger decrease of the in situ meniscus force and greater varus tibial rotation than tears in the rim.

Purpose: Transtibial repair of a medial meniscus posterior root tear (MMPRT) can improve clinical outcomes, although meniscal extrusion remains. However, few studies have investigated the volume of meniscal extrusion. This study aimed to evaluate the effect of transtibial repair in reducing the volume using three-dimensional (3D) magnetic resonance imaging, at 10° and 90° knee flexion., Methods: Twenty patients with MMPRTs and 16 volunteers with normal knees participated. The 3D models of meniscus were constructed using SYNAPSE VINCENT ® . The meniscal extrusion and its volume were measured at 10° and 90° knee flexion. Differences between the pre- and postoperative examinations were assessed using the Wilcoxon signed-rank test. The postoperative parameters were compared to those in patients with normal knees., Results: There were no significant pre- and postoperative differences in any parameter at 10° knee flexion. At 90° knee flexion, the posterior extrusion and its meniscal volume were decreased significantly after transtibial repair (p < 0.05), even though these parameters were larger than in the normal knees. On the other hand, intra-articular meniscal volume calculated by the extrusion volume was increased to the level of the normal knee., Conclusions: This study demonstrated that transtibial repairs improved the intra-articular/intra-tibial surface volume of the medial meniscus by reducing the posteromedial extrusion during knee flexion. This 3D analysis is clinically relevant in evaluating that, while transtibial root repair has a limited ability to reduce meniscal extrusion, it can restore the functional volume of the medial meniscus which contributes to the shock absorber postoperatively., Level of Evidence: IV.

Because of their increased mobility, lack of resistance to hoop stresses, and decreased blood supply, radial tears of the lateral meniscus are more troublesome to heal than vertical longitudinal tears. Given the success of meniscal root repairs, radial tears of the lateral meniscal body should be given strong consideration for repair because of a more reproducible ability to heal such lesions in young, active patients. Technique options that should be considered for the less common anterior radial tears of the lateral meniscus include outside-in repair, self-capturing suture-passing devices, and orthobiologic treatments to stimulate healing. Although a variety of suture techniques, including the double horizontal mattress and horizontal butterfly patterns, have demonstrated improvements in patient outcomes, evidence is still limited with regard to the ideal suture pattern for radial tears.

Purpose: This study aimed to clarify the advantages of three-dimensional (3D) magnetic resonance imaging (MRI) over two-dimensional (2D) MRI in measuring the size of the medial meniscus (MM) and to analyse the volumes of MM and the extruded meniscus in patients with MM posterior root tear (MMPRT), at 10° and 90° knee flexion., Methods: This study included 17 patients with MMPRTs and 15 volunteers with uninjured knees. The MMs were manually segmented for 3D reconstruction; thereafter, the extruded part separated from the tibial edge was determined. The length, width, height, and extrusion of MM were measured by the 2D and 3D methods, and compared. The MM volume, extruded meniscus volume, and their ratio were also calculated using 3D analysis software in the two groups., Results: The estimated length and posterior height of MM were larger with 3D MRI than with 2D MRI measurements. The MM volume was significantly greater in MMPRT knees than in normal knees, with increasing MM height. In MMPRT knees, the mean volume of the extruded meniscus and its ratio significantly increased by 304 mm 3 (p = 0.02) and 9.1% (p < 0.01), respectively, during knee flexion., Conclusions: This study demonstrated that 3D MRI could estimate the precise MM size and that MMPRT caused swelling of the meniscus due to the increased thickness in the posteromedial part. The clinical significance of this study lies in its 3D evaluation of MM volume, which should help the surgeon understand the biomechanical failure of MM function and improve MMPRT repair technique., Level of Evidence: III.

Purpose: Voluntary femoro-tibial subluxation is a rare entity predominantly found in pretoddlers. It presents as a dynamic phenomenon with uni- or bilateral audible snapping of the knee, often in a context of fatigue or irritation at the end of the day. The aim of the study was to observe the evolution and recovery in these patients., Methods: Ten children were included. Other causes of dislocating joints and pathologies with snapping of the lateral meniscus were excluded from this study. Six-week immobilisation with a splint at 70° of knee flexion was primarily recommended to all patients., Results: The mean age at onset of symptoms was 10 months. Forty percent of the patients presented with bilateral symptoms. Clinically, four patients were hyperlax. In all patients, subluxations could be reproduced passively by rotating the foot externally and advancing the internal tibial plateau anteriorly. Three of the patients were treated with a dorsal splint and experienced significantly less or cessation of symptoms. Two patients underwent surgery, one for a concomitant anterior cruciate ligament (ACL) rupture and meniscus tear that worsened the symptoms, another for concomitant patella dislocation and a meniscus tear. One patient's parents refused treatment and four patients experienced less symptoms at the time of consultation and were not immobilized. Except for the two patients undergoing surgeries, no sequelae were observed. In general, the symptoms got less frequent when the patient began to walk., Conclusion: Voluntary femoro-tibial subluxation in children is a rare and benign condition that often resolves spontaneously without sequelae. The risk of meniscus tear should, however, be considered if subluxations do not cease., Level of Evidence: IV.

Purpose: Most studies have concentrated on the changes in contact pressure and area on the tibiofemoral joint. This study compared the contact mechanics underneath the medial meniscus of a repaired vertical longitudinal tear with that of the intact or the torn ones., Methods: In this controlled laboratory study, a 1000 N compressive axial load was applied to eight fresh-frozen cadaveric knees at four flexion angles and four loading conditions using a custom testing apparatus attached to a material testing machine. Intact knees, knees with a medial meniscus vertical longitudinal tear, and knees after meniscal repair were tested. The peak contact pressure and area underneath the meniscus were measured using Fuji pressure-sensitive film., Results: A medial meniscus vertical longitudinal tear significantly increased the contact pressure and decreased contact area underneath the meniscus compared with those at the intact meniscus under all tested biomechanical conditions, and repair of the tear can restore the contact pressure and area in most conditions. While the repaired group showed a significantly higher or similar contact pressure compared with the tear group at 90° neutral knee position and at 60°, 90° 5 N·m-external rotation and 134 N-anterior tibial translation, and 5 N·m-internal rotation at all flexion angles. The contact area corresponding to the aberrant result of the contact pressure in the repaired group was lower than in the intact meniscus group., Conclusions: The contact mechanics underneath the meniscus of the repaired medial meniscus vertical longitudinal tear were significantly improved compared with the corresponding tear conditions in most cases, while the contact pressure and area at some certain status after repair were not significantly different from those of the corresponding tear conditions.

Objective: To evaluate progression of individual radiographic features 5 years following exercise therapy or arthroscopic partial meniscectomy as treatment for degenerative meniscal tear., Design: Randomized controlled trial including 140 adults, aged 35-60 years, with a magnetic resonance image verified degenerative meniscal tear, and 96% without definite radiographic knee osteoarthritis. Participants were randomized to either 12-weeks of supervised exercise therapy or arthroscopic partial meniscectomy. The primary outcome was between-group difference in progression of tibiofemoral joint space narrowing and marginal osteophytes at 5 years, assessed semi-quantitatively by the OARSI atlas. Secondary outcomes included incidence of radiographic knee osteoarthritis and symptomatic knee osteoarthritis, medial tibiofemoral fixed joint space width (quantitatively assessed), and patient-reported outcome measures. Statistical analyses were performed using a full analysis set. Per protocol and as treated analysis were also performed., Results: The risk ratios (95% CI) for progression of semi-quantitatively assessed joint space narrowing and medial and lateral osteophytes for the surgery group were 0.89 (0.55-1.44), 1.15 (0.79-1.68) and 0.77 (0.42-1.42), respectively, compared to the exercise therapy group. In secondary outcomes (full-set analysis) no statistically significant between-group differences were found., Conclusion: The study was inconclusive with respect to potential differences in progression of individual radiographic features after surgical and non-surgical treatment for degenerative meniscal tear. Further, we found no strong evidence in support of differences in development of incident radiographic knee osteoarthritis or patient-reported outcomes between exercise therapy and arthroscopic partial meniscectomy., Trial Registration: www.clinicaltrials.gov (NCT01002794)., (Copyright © 2020 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Background: Lateral thrust is known to be risk factors for knee osteoarthritis progression. Medial meniscus extrusion is also known to be risk factors for knee osteoarthritis progression; moreover, the amount of change in medial meniscus extrusion from non-weight bearing to weight bearing is an important factor for the progression of knee osteoarthritis. This study aimed to investigate the correlation between lateral thrust and the change in medial meniscus extrusion., Methods: In total, 44 knees from 44 patients (mean age, 68.9 years) with knee osteoarthritis were divided into two groups according to the Kellgren-Lawrence grade: early-stage osteoarthritis (Kellgren-Lawrence = 2) and severe osteoarthritis (Kellgren-Lawrence = 3 or 4). The lateral thrust during gait, represented as the lateral acceleration peak immediately after heel strike, was recorded by an inertial sensor. The amount of change in medial meniscus extrusion, which was the difference between weight-bearing (unipedal standing) and non-weight-bearing (supine) conditions, was evaluated using ultrasonography., Results: The mean value of the lateral acceleration peak in the severe osteoarthritis group was higher than that of the early-stage osteoarthritis group (p < 0.05). The non-weight-bearing and weight-bearing medial meniscus extrusion in the severe OA group were significantly higher than those of the early-stage osteoarthritis group (p < 0.001). However, the amount of change in medial meniscus extrusion in severe osteoarthritis group was significantly lower than in the early-stage osteoarthritis group (p < 0.05). The amount of change in medial meniscus extrusion showed a significant correlation with the lateral acceleration peak in the early-stage osteoarthritis group (r = 0.56, p < 0.001). On the other hand, there was no significant correlation in the severe osteoarthritis group., Conclusion: The lateral thrust shows a positive correlation with the amount of change in medial meniscus extrusion by weight bearing in patients with early-stage knee osteoarthritis., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Objectives: Meniscus repair is a challenge for a practitioner, as an injured meniscus can lead to osteoarthritic joint changes with a greatly disabling outcome. Platelet-rich plasma has been regarded as a promising therapy to help induce healing. The purpose of the study is to clinically assess the effectiveness of PRP treatment in adolescents with meniscal lesions., Methods: This retrospective study analyzed 30 patients with meniscal tears, aged 12 to 17 years, who had documented MRI meniscal lesion and persistent knee pain. In order to evaluate the outcome, the Lysholm knee scoring scale and numerical rating scale were used before injection and 3 months after treatment., Results: Patients had a mean age of 13.93 years, 70% girls and 30% boys. The most affected was the medial meniscus. The mean value before injection on the numerical rating scale (NRS) of pain was 7.73, after the treatment being of 2.0. After treatment, 76.7% of the patients had "excellent" and "good" outcomes, while before injection, just 3% of the patients had a "good" score., Conclusions: Platelet-rich plasma treatment can be effective in improving the clinical outcomes of adolescent patients with meniscus tears, for whom conservative management and physical therapy have failed to achieve pain relief., Competing Interests: The authors declare that there is no conflict of interest., (Copyright © 2020 Mihai Bogdan Popescu et al.)

Purpose: To investigate the influences of time from injury to surgery and meniscal injuries on knee rotational laxity in anterior cruciate ligament (ACL)-deficient knees using the electromagnetic system retrospectively., Methods: Ninety-four unilateral ACL-injured patients (44 male and 50 female, mean age: 27.3 ± 11.8 years) were included. The pivot-shift test was performed before ACL reconstruction, as was a quantitative evaluation using the electromagnetic system to determine tibial acceleration. Patients were divided into 4 groups according to the chronicity: group 1, within 3 months (22 patients); group 2, between 3 and 6 months (29 patients); group 3, between 6 and 12 months (23 patients); and group 4, more than 12 months (20 patients). The presence of meniscal injuries was examined arthroscopically., Results: The tibial acceleration was significantly greater in group 4. There was a positive correlation between tibial acceleration and the time from injury to surgery (r = 0.47, P = .02). In groups 1, 2 and 3, the tibial acceleration in patients with a lateral meniscal injury was significantly greater than in patients with a medial meniscal injury and without meniscal injury. When patients with lateral meniscal injury were excluded (leaving those with medial meniscus injury or without meniscal injury), group 4 had significantly greater accelerations than other groups., Conclusions: In ACL-deficient knees, rotational laxity increased with time and the increased rotational laxity was evident more than 1 year after injury whereas it increased with concomitant lateral meniscal injuries within 1 year after injury., Level of Evidence: Ⅳ, diagnostic study of nonconsecutive patients., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Objective: The present study was undertaken to evaluate changes in knee magnetic resonance imaging (MRI) findings over the course of 18 months in subjects with osteoarthritic change and meniscal tear treated with arthroscopic partial meniscectomy (APM) or nonoperatively with physical therapy (PT)., Methods: We used 18-month follow-up data from the Meniscal Tear in Osteoarthritis Research Trial. MRI results were read with reference to the MRI Osteoarthritis Knee Score. We focused on 18-month change in bone marrow lesions (BMLs), cartilage thickness, cartilage surface area, osteophyte size, effusion-synovitis, and Hoffa-synovitis. We used multinomial logistic regression to assess associations between MRI-based changes in each feature and treatment type., Results: A total of 351 subjects were randomized, and 225 had both baseline and 18-month MRI results. In both treatment groups, patients experienced substantial changes in several MRI-based markers. In 60% of the APM group, versus 33% of the PT group, cartilage surface area damage advanced in ≥2 subregions (adjusted odds ratio 4.2 [95% confidence interval 2.0-9.0). Patients who underwent APM also had greater advancement in scores for osteophytes and effusion-synovitis. We did not find significant associations between treatment type and change in cartilage thickness, BMLs, or Hoffa-synovitis., Conclusion: This cohort of patients with meniscal tear and osteoarthritis showed marked advancement in MRI-based features over 18 months. Patients treated with APM showed more advancement in some features compared to those treated nonoperatively. The clinical relevance of these early findings is unknown and requires further study., (© 2019, American College of Rheumatology.)

Objective: The purpose of this systematic review and meta-analysis was to evaluate the efficacy of arthroscopic partial meniscectomy (APM) for symptomatic degenerative meniscal tear (DMT) in knees with mild or no osteoarthritis., Study Design: A systematic review and meta-analysis., Methods: MEDLINE, EMBASE, and Cochrane databases were systematically searched. The inclusion criteria were as follows: (1) English language; (2) randomized controlled trial (RCT); (3) comparison between APM and other treatment modalities as a primary objective; and (4) complete DMT in knees with mild or no osteoarthritis. Mild or no arthritis was defined as Kellgren-Lawrence grade 0 to 2 or Ahlbäck 0 to 1 on radiography. Statistical analysis of functional activity and pain after APM and conservative treatment or sham operation was performed using R version 3.3.1., Results: Five articles were included in the final analysis, and they were all RCTs. Four studies compared clinical results of APM with those for physical therapy, and one study compared APM with sham operation. The functional activity was not better in the APM group (296 cases) than in the conservative treatment or sham operation group (284 cases) (I: 0%, small level of heterogeneity). Pain was not reduced significantly in the APM group compared with that in the conservative treatment or sham operation group (I: 0∼90%, high level of heterogeneity)., Conclusions: This systematic review and meta-analysis of high-quality literature provides relatively strong evidence that APM did not improve functional activity or reduce pain compared with the results with conservative treatment or sham operation in knees with mild or no osteoarthritis.

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.

We established an effective finite element model of knee joint for observation of stress and displacement of meniscus related changes after medial meniscus injury. Different types of medial meniscus injury can lead to varied meniscus stress and displacement changes. Stress and displacement concentration were found in fissure tip of meniscus tear compared to normal meniscus. The posterior horn injury of medial meniscus may initiate combined injury of medial meniscus posterior horn (MMPH) and that of medial meniscus body, and combined injury of MMPH and that of lateral meniscus anterior horn; fissure expansions regarding horizontal fissure, longitudinal fissure and grip-shaped fissure of MMPH were spotted.

Background: In the anterior cruciate ligament (ACL) injured knee, additional injury of the anterolateral ligament (ALL) and capsule may increase the pathologic laxity. The purpose of this study was to compare the effects of the anterolateral complex (ALC) injury in ACL injured knee with the effects of lateral meniscus posterior horn (LMPH) meniscectomy., Methods: Ten fresh-frozen cadaveric knees were used. After testing the (1) intact knees and (2) ACL sectioned knees (ACL-), two groups were established: an (3) ALC sectioning group (n = 5), which underwent additional ALC sectioning (ACL-/ALC-) after ACL sectioning, and a separate (3) LMPH meniscectomy group (n = 5) that underwent LMPH meniscectomy (ACL-/LMPH-) after ACL sectioning. Knee laxity was measured in terms of internal-external rotation, anterior-posterior translation, and varus-valgus angulation for each condition at knee flexion angles of 0°, 30°, 60° and 90°., Results: After additional sectioning of the ALC (ACL-/ALC-), the mean internal rotation at 0, 30, 60 and 90° of knee flexion was 11.9 ± 1.3°, 18.1 ± 1.6°, 18.3 ± 1.8°, and 17.8 ± 2.4°, respectively, showing significant internal rotation laxity when compared to the intact knee (P = .031, .020, .001 and .033). Anterior translation also significantly increased compared to the ACL- knee at 30° (12.7 ± 1.4 to 16.8 ± 1.7 mm: P = .039). In contrast, additional meniscectomy of the LMPH (ACL-/LMPH-) significantly increased valgus laxity compared to the intact knee at 30, 60 and 90° (P = .021, .018 and .024)., Conclusion: These findings suggest that the anterolateral complex, which include the ALL and anterolateral capsule, may play an important role in stabilizing the knee against internal rotation and anterior translation., Competing Interests: Declaration of competing interest Ji Hyun Ahn and Thay Q. Lee have received research grants from Smith and Nephew Company. Ji Hyun Ahn has also received research grants from Dongguk University. In Jun Koh, Michelle H. McGarry, Nilay A. Patel, Charles C. Lin and Sangwoo Kim declare that they have no conflict of interest. All authors do not have any financial and personal relationships with other people or organizations that could inappropriately influence the current work., (Copyright © 2019 Elsevier B.V. All rights reserved.)

One of the factors affecting the healing of a meniscus repair is the primary stability of the tear. The purpose of this study is to compare single and double vertical loop (SVL vs. DVL) meniscal suture configurations by measuring elongation under cyclic loading and failure properties under ultimate load. We hypothesized that DVL configuration would have superior biomechanical properties than SVL. Twenty-two intact lateral menisci were harvested from patients who required total knee arthroplasty. A 20-mm longitudinal full-thickness cut was made 3 mm from the peripheral rim to simulate a longitudinal tear. Two groups were formed and group randomization was done according to patient age and gender (SVL group: mean age 68.3 years [range, 58-78 years], five males, six females; DVL group: mean age 67.4 years [range, 59-77 years], six males, five females). Cyclic loading was performed between 5 and 30 N at a frequency of 1 Hz for 500 cycles. Then, the meniscus repair construct was loaded until failure. Statistical analysis was performed using the t -test and the Mann-Whitney's U -test. During the early phases of cyclic loading, three specimens from each group failed because of suture pull out and are excluded from the study. At the end of 500 cycles, there was significantly less displacement in the DVL group than the SVL group (6.13 ± 1.04 vs. 9.3 ± 2.59 mm) ( p  < 0.05). No significant difference was found between groups regarding ultimate load to failure measurements ( p  > 0.05). All specimens in SVL and five specimens in DVL groups failed in the form of suture pull out from the meniscus tissue. Longitudinal meniscal tears repaired with DVL configuration had less elongation value under cyclic loading compared with SVL configuration. Because of its superior biomechanical properties, it would be more secure to repair large and instable longitudinal meniscal tears by the DVL technique. This is a level II study., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Increased posterior tibial slope and posterior medial meniscus root tears increase the force experienced by the anterior cruciate ligament (ACL) and predispose patients to higher rates of primary ACL injury or ACL graft failure after an ACL reconstruction (ACLR). However, the interplay among sagittal plane tibial slope, medial meniscus root tears, and ACLR graft force remains inadequately defined., Purpose/hypothesis: The purpose was to quantify the effect of sagittal plane tibial slope on ACLR graft force at varying knee flexion angles with an intact medial meniscus, a posterior medial meniscus root tear, and a medial meniscus root repair. Our null hypothesis was that changes in slope and meniscal state would have no effect on the forces experienced by the ACLR graft., Study Design: Controlled laboratory study., Methods: Ten male fresh-frozen cadaveric human knees underwent a posteriorly based high tibial osteotomy. A spanning external fixator and wedges of varying sizes were used to stabilize the osteotomy and allow for accurate slope adjustment. After ACLR, specimens were compressed with a 1000-N axial load at flexion angles of 0° and 30° for each of the 3 meniscal states and at tibial slopes of 0° to 15° at 3° increments. Graft loads were recorded through a force transducer clamped to the graft., Results: Increasing tibial slope led to a linear increase in ACLR graft force at 0° and 30° of knee flexion. Posterior medial meniscus root tear led to significant increases in ACLR graft forces over the intact state, while root repair restored the function of the medial meniscus as a secondary stabilizer. At 30° of knee flexion, the tibial slope effect on ACLR graft force was potentiated in the root tear state as compared with the intact and root repair states-test of interaction effect: t (139) = 2.67 ( P = .009)., Conclusion: Increases in tibial slope lead to a linear increase in ACLR graft forces, and this effect is magnified in the setting of a posterior medial meniscus root tear. At slopes >12°, a slope-changing osteotomy could be considered in the setting of a revision ACLR with a concomitant medial meniscus root tear., Clinical Relevance: Defining the relationship between tibial slope and varying states of meniscal insufficiency can help determine when it may be necessary to perform a slope-decreasing proximal tibial osteotomy before ACLR and meniscal repair.

Purpose: To compare the serial changes in radiographic outcomes in terms of the mechanical axis (MA) angle and medial joint space width (JSW) between medial meniscus posterior root tear (MM PRT) and non-root tear (MM NRT) after arthroscopic partial meniscectomy (APM)., Methods: Patients who underwent APM for degenerative MM PRT or MM NRT from January 1999 to July 2012 were retrospectively reviewed. One hundred ten patients each in the MM PRT group and the MM NRT group, who were matched through propensity score matching (adjusting for confounding factors such as age, sex, body mass index, anatomic axis, cartilage state of the medial compartment, and follow-up period), were included in the study. The MA angle on weightbearing whole-leg radiographs and the medial JSW on weightbearing 45° flexion posteroanterior radiographs were measured to evaluate the radiographic outcomes. The serial changes were compared between radiographs taken before surgery, at postoperative 3 to 5 years, and at postoperative 5 years to the last follow-up. The linear mixed model was used to compare the changes in radiographic outcomes during the follow-up period between groups., Results: The 2 groups were balanced with standardized mean differences of <0.2 after propensity score matching. Both the MM PRT and NRT groups showed increased varus alignment after surgery. However, there was no significant difference in the change in the MA angle during the follow-up period between groups (P = .182). The medial JSW also showed progression of joint space narrowing after surgery in both groups; however, there was no significant difference in the change in medial JSW during the follow-up period between groups (P = .270)., Conclusion: The radiographic outcomes after partial meniscectomy in terms of the MA angle and medial JSW show comparable results between degenerative MM PRT and NRT after proper matching of confounding factors., Level of Evidence: Level III, retrospective comparative study., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Meniscus surgery has dramatically changed over the last 20 years. This article reviews the advances and current evidence in meniscus repair.

Anterior cruciate ligament injuries are commonly combined with meniscal tears. This study was performed to analyze the kinematics and kinetics of knees with anterior cruciate ligament deficiency with or without a combined medial or/and lateral meniscal injury during level walking. In all, 29 patients with unilateral anterior cruciate ligament deficiency and 15 healthy male volunteers were recruited. Among these patients, 12 had isolated unilateral anterior cruciate ligament injuries (ACLD group), 5 had combined anterior cruciate ligament and lateral meniscal injuries (ACLDL group), 5 had combined anterior cruciate ligament and medial meniscal injuries (ACLDM group), and 7 had combined anterior cruciate ligament and medial/lateral meniscal injuries (ACLDML group). A subject-specific musculoskeletal multibody dynamics model was utilized to estimate the tibiofemoral joint kinematic and kinetic behaviors based on the experimental data measured by using an optical tracking system. Regardless of the presence or absence of meniscal injury, the knees with anterior cruciate ligament deficiency exhibited significantly less extension than the control knees at the terminal stance (range of extension: ACLD, 4.84° ± 4.31°; ACLDL, 6.65° ± 5.73°; ACLDM, 5.21° ± 4.77°; ACLDML, 6.91° ± 4.30°; control, 12.35° ± 5.52°; P  < 0.05). A lower extension moment and adduction moment in all anterior cruciate ligament deficiency affected knees were detected during the terminal stance when compared with control knees ( P  < 0.05). The ACLDML group showed significantly lower proximal-distal compressive forces and anterior-posterior shear forces (approximately 0.5-1.5 body weight; P  < 0.05) compared to the other 4 groups, while the anterior-posterior and medial-lateral shear forces tended to increase in the ACLD, ACLDL, and ACLDM groups at the mid to terminal stance. Significant lower adduction-abduction and internal-external moment peaks were observed in ACLDML groups, but not in the ACLD, ACLDL and ACLDM groups. These results indicate that the combination of an anterior cruciate ligament injury and meniscal injury could alter the kinematics and kinetics of anterior cruciate ligament deficiency affected knees depending on the presence and type of the meniscal tear.

Purpose: The purpose of this study was to investigate the biomechanical properties of load distribution following a centralization procedure for extruded lateral menisci with posterior root deficiency in a porcine model., Methods: Six porcine knee joints were analyzed in a universal tester, as follows: 1) Intact; 2) Extrusion (meniscus extrusion was created by resecting the posterior root of the lateral meniscus, as well as the posterior synovial capsule); and 3) Centralization (two anchors were inserted at the lateral tibial plateau, and the meniscus was sutured to secure it close to the original position). Meniscus extrusion was evaluated using two markers put on the posterior cruciate ligament and the lateral meniscus, and the load distribution were assessed using a pressure mapping sensor system after applying a loading force of 200 N to the knee joint., Results: Distance between two markers (mm, Average; 95% CI) was larger in the extrusion group (21.9; 17.8, 25.6) than in the intact (18.1; 15.1, 22.7) or the centralization (15.3; 12.9, 18.0) groups. The contact area (mm 2 ) in the middle of the meniscus was significantly smaller in the extrusion group (45.8; 18.5, 73.2) than in the intact (85.7; 72.1, 99.2) or the centralization (98.3; 88.8, 107.8) groups. The maximum contact pressure (MPa) in the tibial plateau was significantly higher in the extrusion group (0.37; 0.35, 0.40) than in the intact (0.29; 0.21, 0.37) or the centralization (0.29; 0.22, 0.36) groups., Conclusions: The centralization procedure enabled a reduction of the meniscus extrusion in the lateral meniscus with posterior root deficiency and restored the maximum load and contact pressure to values close to those of the normal knee joint., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

The menisci are 2 fibrocartilaginous crescents anchored via bony and ligamentous attachments to surrounding structures. Their biochemical composition and multilayered structure make them ideal for converting compressive forces to tensile forces in addition to improving joint congruity and providing shock absorption to weight bearing. The medial meniscus maintains more attachments at both the horns and the midbody than the lateral meniscus, making it more susceptible to injury. Understanding of the gross anatomy, vascular anatomy, biochemical composition, and microstructure is key to understanding causes of meniscal pathology as well as treatment options for restoring its primary functions., (Copyright © 2019 Elsevier Inc. All rights reserved.)

» Injuries to the posterior root of the lateral meniscus occur frequently in acute knee injuries with concomitant tearing of the anterior cruciate ligament (ACL). » The meniscofemoral ligaments (MFLs), consisting of the anterior MFL (ligament of Humphrey) and the posterior MFL (ligament of Wrisberg), as well as the osseous attachment of the meniscal root, stabilize the lateral meniscus, enabling appropriate load transmission and maintenance of contact forces within the lateral compartment of the knee during loading and range of motion. » In the setting of an ACL injury to the knee with osseous root injury of the posterior root of the lateral meniscus, the MFLs (when present) may stabilize the lateral meniscus against meniscal extrusion, thereby maintaining appropriate contact mechanics within the knee, decreasing the risk of subsequent chondral and meniscal injury and the development of premature osteoarthritis. » Additional study on the indications for posterior meniscal root repair during ACL reconstruction is warranted since the ideal management of lateral root injury in the MFL-intact knee remains unknown.

Meniscal ramp lesions occur much more frequently than was previously considered, and particularly so in ACL-injured knees. The historically high rate of missed diagnoses is a result of unfamiliarity with this injury pattern within the orthopedic community, and also the difficulty in diagnosis. A systematic exploration of the posteromedial compartment of the knee is mandatory to reliably identify ramp lesions. Failure to recognize and repair these injuries is associated with persistent anterior and posteromedial instability. Understanding their nature, biomechanics, and epidemiology is essential in allowing orthopedic surgeons to suspect their presence and adequately treat these lesions., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

The meniscus plays an important, complex role in maintaining the homeostasis and health of the knee. Meniscal tears are a risk factor for early chondral injury and eventually knee osteoarthritis. There is a growing body of evidence about the early biological changes associated with meniscal injury that likely start the process of joint degeneration. This review highlights the basic science, translational and clinical studies of the detrimental effects of meniscal injury and deficiency on the biology of the knee., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Football players frequently face the occurrence of non-contact injuries. Although there are likely multiple factors that contribute to increased risk of non-contact injury, it remains a challenge to correlate all these factors. However, it is not clear how much of individual training abilities may interfere in these events. As such, the primary aim of the present study was to determine whether the reduction of functional performance of the thigh in the isokinetic knee tests, anthropometric and morbid history can establish risk factors for lower-limb musculoskeletal injuries throughout the season. The incidence of injuries and odds ratios were calculated for suspected risk factors. Hamstring/Quadriceps conventional ratio outside of the safety range (55-64%) may be involved in the occurrence of non-contact muscle injuries and the risk for any musculoskeletal injuries in the lower extremities is 16 times higher when extensor peak of torque exceeds 10% and 12 times higher when flexor peak of torque difference was greater than 10%. This kind of evaluation can result in intervention programs that may decrease the risk of lower-limb musculoskeletal injuries. Based on these results we can establish a specific and individualized exercise program for each athlete and thus protect them during the season., Competing Interests: Authors declare that they have no conflict of interest., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: The treatment of meniscal tears in the avascular region remains a clinical challenge. Extracorporeal shockwave therapy (ESWT) is a minimally invasive, safe, and effective therapy for various orthopaedic disorders. However, the therapeutic effect of ESWT on meniscal tears has not been reported., Purpose: To evaluate the therapeutic effect of ESWT in the treatment of meniscal tears., Study Design: Controlled laboratory study., Methods: Twelve-week-old male Wistar rats were divided into 3 groups (normal, ESWT-, and ESWT+). The authors made a full-thickness 2-mm longitudinal tear in the avascular region of the anterior horn in the latter 2 groups. At 1 week after surgery, the ESWT+ group received 800 impulses of shockwave at 0.22-mJ/mm 2 energy flux density in a single session. The authors performed a histological examination to evaluate meniscal healing (n = 10 for each group) and immunohistochemistry to analyze the expression of bromodeoxyuridine (BrdU; n = 5 for each group) and CCN family member 2/connective tissue growth factor (CCN2/CTGF; n = 5 for each group) at 2, 4, and 8 weeks after ESWT. The mRNA levels of CCN2, SOX 9, VEGF-a , aggrecan, Col1a2 , and Col2a1 at the site of the meniscal tear at 4 weeks after ESWT were quantitatively evaluated by a real-time polymerase chain reaction (n = 5 for each group)., Results: The meniscus healing scores in the ESWT+ group were significantly higher than those in the ESWT- group at 4 weeks and 8 weeks. The ratio of BrdU-positive cells was the highest in the ESWT+ group at all observation periods. The ratio of CCN2-positive cells was highest in the ESWT+ group at 4 and 8 weeks. In the ESWT+ group, real-time polymerase chain reaction revealed that the levels of CCN2, SOX9 , aggrecan, and Col2a1 were upregulated (All significant data were P < .05)., Conclusion: ESWT promoted the healing of meniscal tears in the avascular area. ESWT stimulated proliferation of meniscal cells and the upregulation of cartilage-repairing factors such as CCN2, with the upregulation of cartilage-specific extracellular matrix expression., Clinical Relevance: ESWT may be an effective therapeutic option that promotes meniscal healing in the avascular region.

Anatomical reinsertion is the optimal treatment for meniscal root injuries. However, in chronic settings, tissue fraying of the meniscal root may impede it. This study describes a salvage technical procedure performed in 3 cases of chronic anterior root avulsion of the lateral meniscus with profuse tissue degeneration in which remnant debridement resulted in amputation of the root. Reinsertion of the meniscus at the remaining healthy tissue was performed using an all-inside anchoring technique., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Purpose: The assisted inferior anterolateral portal under anterior horn of the lateral meniscus (UAHLM portal) was applied to treat the lateral discoid meniscus injury conveniently and the clinical outcomes were evaluated., Methods: A retrospective review was conducted on 60 patients who underwent arthroscopic surgery with a symptomatic discoid lateral meniscus. Normal anterolateral/anteromedial portals assisted with UAHLM portal (1-2 cm inferior to the anterolateral portal) were used. All patients were followed up for 24-48 months (median, 33 months) and evaluated by MRI images and clinical outcomes including clinical findings, Lysholm scores and IKDC scores., Results: After meniscus plasty with or without repair, most of the upper layer of lateral meniscuses was retained. A total of 54 patients (16 males and 38 females, 42 ± 17.8 years old) showed satisfactory clinical results without requiring reoperation after a median follow-up time of 33 months. At final follow-up, a full range of motion was achieved in all patients. MRI indicated the thickness of anterior horn of lateral meniscus was (5.38 ± 1.09 mm) before the operation and (4.04 ± 0.71 mm) after the operation at the 2-year follow-up; clinical outcomes were improved significantly than the baseline: positive McMurray test (50 vs. 2, P< 0.001), Lysholm score (64.9 ± 9.0 vs. 94.7 ± 4.9, P< 0.001), and IKDC score (54.4 ± 7.7 vs. 92.6 ± 4.3, P< 0.001). No significant complication was observed during the follow-up., Conclusion: Thus, this technique with assisted UAHLM portal was convenient for arthroscopic discoid meniscus plasty and meniscus repair and served as an effective method in patients with a symptomatic discoid lateral., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Purpose: To investigate the prevalence of the anterolateral ligament (ALL) injuries and its role in rotatory laxity in acute anterior cruciate ligament (ACL)-injured knees., Methods: Two-hundred and ninety-six consecutive patients with acute ACL injuries were evaluated retrospectively, excluding those with other ligament injury and undetectable path of ALL in MRI. Patients were divided into two groups based on the degree of ACL injury in arthroscopy (complete versus partial group). Logistic regression and discriminant analysis were performed to assess the risk of pivot shift test., Results: A total of 169 patients were included (128 with complete and 41 with partial ACL rupture). Overall, 106/169 (62.7%) of ALL injuries were characterized, 87/128 (67.9%) in complete group, and 19/41 (46.3%) in partial group. The incidence of pivot shift was 120/128 (93.8%) and 14/41 (34.1%) in the complete and partial groups, respectively. The odds ratio in the pivot shift of combined ALL injury was found as 3.8 (95% CI 1.8-8.4) with the overall ACL injury, but higher as 17.1 (95% CI 3.1-96.4) with partial group. Higher grade of pivot shift showed a greater incidence of injury of ALL. Degree of ACL injury and ALL injury allowed 87.0% of correct classification of subsequent anterolateral rotatory laxity., Conclusion: Injury to the ALL could have a synergetic effect on anterolateral rotatory laxity in acute ACL-injured knee, however, its effect might be minor in case of complete tear. Careful assessment about combined ALL injury should be considered, especially in knees with high-grade pivot shift in acute ACL-injured knees., Level of Evidence: Retrospective prognostic study, Level IV.