Search

Purpose/Aim of the study: Posterior root injury of the medial meniscus often leads to articular cartilage degeneration due to altered biomechanics. To avoid dysfunction, the attachment must be repaired using the transtibial pullout technique. To guide appropriate placement of the tibial tunnel, additional details on the normal anatomy of the meniscus insertion are needed. Therefore, we performed a histological analysis of a tibial bone slice with the medial meniscus posterior insertion obtained during total knee arthroplasty surgery. Materials and methods: Horizontal slices of the proximal tibia were obtained from 7 patients with osteoarthritis who underwent total knee arthroplasty. After decalcification, the region of the posterior horn was cut out and segmented into four pieces (2.0 mm thickness; medial to lateral). Sagittal sections were evaluated by safranin O staining or immunohistochemistry with anti-type collagen antibody. Results: Safranin O staining showed that the insertion of the posterior root consisted primarily of fibrocartilaginous layers in segment 2. Anatomically, segment 2 corresponded to the sagittal plane passing through the peak of the medial intercondylar tubercle. In this section, safranin O staining and immunohistochemistry revealed that the anterior one-third of the posterior root insertion was richer in proteoglycans and type II collagen than the central and posterior one-third. Conclusions: Anatomical insertion of the posterior root of the medial meniscus was located at the sagittal plane passing through the peak of the medial intercondylar tubercle. The structure of the medial meniscus posterior insertion was mainly localized in the anterior one-third.

PURPOSE: Medial meniscus posterior root tear (MMPRT) leads to a rapid degradation of articular cartilage. In the treatment of MMPRT, transtibial pullout repair demonstrates a high clinical survival rate. However, there is no reliable method to evaluate the meniscal healing after surgery. We propose an arthroscopic scoring system for evaluating the meniscal healing status. The aim of this study was to investigate the correlations between second-look arthroscopic scores and clinical outcomes after transtibial pullout repair. METHODS: Twenty patients who had MMPRTs underwent transtibial pullout repairs. Clinical outcomes were assessed using the Japanese Knee Injury and Osteoarthritis Outcome Score (KOOS) and pain score evaluated by visual analogue scale at preoperatively and 1 year postoperatively. The healing status of repaired MM was assessed at one year post-operatively using a semi-quantitative arthroscopic scoring system (total, 10 points) composed of three evaluation criteria: (i) anteroposterior width of bridging tissues, (ii) stability of the MM posterior root, and (iii) synovial coverage of the sutures. Linear regression analysis was used to assess the correlation between second-look arthroscopic scores and clinical outcomes. RESULTS: Transtibial pullout repairs of MMPRTs significantly improved clinical evaluation scores at one year post-operatively. A median of second-look arthroscopic scores was 6.5 (5.75-8). A good correlation was observed between the arthroscopic score and KOOS quality of life (QOL) subscale. A moderate negative correlation between the arthroscopic score and pain score was observed. CONCLUSIONS: This study demonstrated that our semi-quantitative scoring system of meniscal healing correlated with the KOOS QOL subscale following MMPRT transtibial pullout repair. Our results suggest that the second-look arthroscopic score using this system may be a useful scale to determine and compare the healing status of the MM posterior root.

This study aimed to evaluate the relationship between preoperative lateral meniscal extrusion (LME) and arthroscopic findings of lateral meniscus posterior root tear (LMPRT) in knees with anterior cruciate ligament (ACL) tear. Thirty-five knees that had LMPRTs with concomitant ACL tears on arthroscopy were evaluated. Patients were divided into two groups, partial and complete root tears, via arthroscopic findings at the time of ACL reconstruction. For comparison, we added two groups, using the same database; 20 normal knees (normal group) and 20 ACL-injured knees without LM injury (intact LM group). We retrospectively measured preoperative LMEs using magnetic resonance imaging (MRI). Twenty-three knees had partial LMPRTs. Complete LMPRTs were observed in 12 knees. The average LME was -0.1 ± 0.4 mm in the normal group, 0.2 ± 0.5 mm in the intact LM group, 0.4 ± 0.8 mm in the partial LMPRT group, and 2.0 ± 0.6 mm in the complete LMPRT group. A significant difference in preoperative LMEs was observed between the complete LMPRT group and the other groups (p

Introduction Medial meniscus posterior root tear (MMPRT) leads to abnormal biomechanics of the knee by inducing the medial meniscus extrusion (MME). However, a time-dependent increase of the MME is not fully elucidated in patients suffering from the acute MMPRT. The aim of this study was to investigate the relationships among disease duration of the MMPRT and severity of the MME. We hypothesized that MME measurement correlates with disease duration after a sudden onset of the minor traumatic MMPRT during the short-term follow-up period. Materials and methods Forty-six patients who had an accurate episode of the posteromedial painful popping were investigated. All the patients were diagnosed having a symptomatic MMPRT with magnetic resonance imaging (MRI) examinations. Absolute MME was measured using MRI scans within 12 months after painful popping events. A correlation coefficient between duration from injury to MRI examination and absolute MME was evaluated. Results Mean absolute MME was 4.5 ± 1.6 mm (range, 1.1 − 8.8 mm) on MRI measurements. A good correlation was observed between MME measurement and duration from injury to MRI examination ( R 2 = 0.612). The best-fit equation for predicting each value was: MME = 0.014 × disease duration + 3.288 mm. Discussion This study demonstrated that absolute MME increases progressively within the short duration after the onset of symptomatic MMPRT. Our results suggest that preoperative MME assessment may be important in determining disease duration and treatment strategy of the MMPRT. Level of evidence Retrospective cohort study level IV.

Background To compare the plain knee radiograph finding of tibial eminence width between knees with complete discoid lateral meniscus, incomplete discoid lateral meniscus, and normal lateral meniscus. Materials and methods The study included 27 knees with discoid lateral meniscus, including 13 knees with complete discoid lateral meniscus and 14 knees with incomplete discoid lateral meniscus. A control group of 14 knees with normal lateral meniscus was also included. Tibial eminence width and the lateral slope angle of the medial tibial eminence were assessed using plain frontal knee radiographs. Individual differences in knee size were corrected by dividing tibial eminence width by tibial width to obtain the tibial eminence width percentage. Results Mean tibial eminence width and tibial eminence width percentage in the complete discoid lateral meniscus group was significant larger than other groups. Mean lateral slope angle in the complete discoid lateral meniscus group was significantly smaller than other groups. A tibial eminence width cut-off of 13.9 mm showed a sensitivity and specificity of 100% and 83%, respectively. A tibial eminence width percentage cut-off of 18.8% showed a sensitivity and specificity of 100% and 90%, respectively. A lateral slope angle cut-off of 27.1° showed a sensitivity and specificity of 71% and 83%, respectively. Conclusion There were clear differences in tibial eminence width, tibial eminence width percentage, and lateral slope angle between the complete discoid lateral meniscus group and the other groups. The plain radiographic parameters identified by this study could be useful for complete discoid lateral meniscus screening. Study design Clinical.

BACKGROUND: The posterior root ligament of the medial meniscus (MM) has a critical role in regulating the MM movement. An accurate diagnosis of the MM posterior root tear (MMPRT) using magnetic resonance imaging (MRI) is important for preventing sequential osteoarthritis following the MMPRT. However, diagnosis of the MMPRT is relatively difficult even after using several characteristic MRI findings. The aim of this study was to identify a useful meniscal body sign of the MMPRT for improving diagnostic MRI reading. METHODS: Eighty-five patients who underwent surgical treatments for the MMPRT (39 knees) and other types of MM tears (49 knees) were included. The presence of characteristic MRI findings such as cleft sign, ghost sign, radial tear sign, medial extrusion sign, and new meniscal body shape-oriented "giraffe neck sign" was evaluated in 120 MRI examinations. RESULTS: Giraffe neck signs were observed in 81.7% of the MMPRTs and in 3.3% of other MM tears. Cleft, ghost, and radial tear signs were highly positive in the MMPRTs compared with other MM tears. Medial extrusion signs were frequently observed in both groups. Coexistence rates of any 2 MRI signs, except for medial extrusion sign, were 91.7% in the MMPRT group and 5% in other MM tears. CONCLUSIONS: This study demonstrated that a new characteristic MRI finding "giraffe neck sign" was observed in 81.7% of the MMPRT. Our results suggest that the combination of giraffe neck, cleft, ghost, and radial tear signs may be important for an accurate diagnostic MRI reading of the MMPRT.

BACKGROUND: The meniscus plays an important role in controlling the complex biomechanics of the knee. Meniscus injury is common in the knee joint. The perimeniscal capillary plexus supplies the outer meniscus, whereas the inner meniscus is composed of avascular tissue. Angiogenesis factors, such as vascular endothelial growth factor (VEGF), have important roles in promoting vascularization of various tissues. VEGF-mediated neovascularization is beneficial to the healing of injured tissues. However, the distribution and angiogenic role of VEGF remains unclear in the meniscus and injured meniscus. We hypothesized that VEGF could affect meniscus cells and modulate the meniscus healing process. METHODS: Menisci were obtained from total knee arthroplasty patients. Meniscal injury was created ex vivo by a microsurgical blade. VEGF mRNA and protein expression were detected by the polymerase chain reaction and immunohistochemical analyses, respectively. RESULTS: In native meniscal tissue, the expression of VEGF and HIF-1α mRNAs could not be detected. However, VEGF and HIF-1α mRNAs were found in cultured meniscal cells (VEGF: outer > inner; HIF-1α: outer = inner). Injury increased mRNA levels of both VEGF and HIF-1α, with the increase being greatest in the outer area. Immunohistochemical analyses revealed that VEGF protein was detected mainly in the outer region and around injured areas of the meniscus. However, VEGF concentrations were similar between inner and outer menisci-derived media. CONCLUSIONS: This study demonstrated that both the inner and outer regions of the meniscus contained VEGF. HIF-1α expression and VEGF deposition were high in injured meniscal tissue. Our results suggest that injury stimulates the expression of HIF-1α and VEGF that may be preserved in the extracellular matrix as the healing stimulator of damaged meniscus, especially in the outer meniscus.

The anterior root of the lateral meniscus provides functional stability to the meniscus. In this study, we evaluated the relationship between the position of the tibial tunnel and extrusion of the lateral meniscus after anterior cruciate ligament reconstruction, where extrusion provides a proxy measure of injury to the anterior root. The relationship between extrusion and tibial tunnel location was retrospectively evaluated from computed tomography and magnetic resonance images of 26 reconstructed knees, contributed by 25 patients aged 17-31 years. A measurement grid was used to localize the position of the tibial tunnel based on anatomical landmarks identified from the three-dimensional reconstruction of axial computed tomography images of the tibial plateaus. The reference point-to-tibial tunnel distance (mm) was defined as the distance from the midpoint of the lateral edge of the grid to the posterolateral aspect of the tunnel aperture. The optimal cutoff of this distance to minimize post-operative extrusion was identified using receiver operating curve analysis. Extrusion of the lateral meniscus was positively correlated to the reference point-to-tibial tunnel distance (r 2 = 0.64; p 5 mm was 0.40 ± 0.43 mm, compared to 1.40 ± 0.51 mm for a distance ≤5 mm (p

Highlights • There were no meniscal anomalies such as discoid meniscus and ring-shaped meniscus at the first surgery. • Postoperative MRI showed a ring-shaped lateral meniscus. • On second-look arthroscopy, there was a meniscus-like tissue formation that connected the anterior horn to the posterior horn of the lateral meniscus at the lateral intercondylar tubercle. • The ring-shaped meniscus-like tissue was spontaneously formed after ACL reconstruction., Introduction We presented the first case in the literature of inter-horn bridge formation involved in ring-shaped lateral meniscus after anterior cruciate ligament (ACL) reconstruction. Presentation of case A 22-year-old man underwent anatomic double-bundle ACL reconstruction using semitendinosus tendon autograft. At the surgery, the lateral meniscus showed a normal appearance without meniscal tears and had no instability. There were no meniscal anomalies such as discoid meniscus and ring-shaped meniscus. Magnetic resonance image examination was performed before second-look arthroscopy at 1 year postoperatively. A coronal plane showed a small triangular fragment located at the medial border of the lateral tibial plateau. An axial plane demonstrated a ring-shaped lateral meniscus. On second-look arthroscopy, there was a meniscus-like tissue formation that connected the anterior horn to the posterior horn of the lateral meniscus at the lateral intercondylar tubercle. Discussion Ring-shaped meniscus is an extremely rare malformation of the meniscus. Our hypothesis was that drilling debris and remaining remnant of ACL might induce a scar tissue formation. Conclusion This is the first case in the literature of inter-horn bridge formation involved in ring-shaped lateral meniscus following ACL reconstruction.

A medial meniscus posterior root tear (MMPRT) may increase the tibiofemoral contact pressure by decreasing the tibiofemoral contact area. Meniscal dysfunction induced by posterior root injury may lead to the development of osteoarthritic knees. Repair of a MMPRT can restore medial meniscus (MM) function and prevent knee osteoarthritis progression. Several surgical procedures have been reported for treating a MMPRT. However, these procedures are associated with several technical difficulties. Here, we describe a technique to stabilize a torn MM posterior root using the FasT-Fix® all-inside meniscal suture device and a new aiming device. The uncut free-end of the FasT-Fix® suture can be used as a thread for transtibial pullout repair. Our procedure might help overcome the technical difficulties in arthroscopic treatment of a MMPRT.

Venous thromboembolism (VTE) is a potential complication occurring after total knee arthroplasty (TKA). We investigated the incidence of VTE after TKA using contrast-enhanced computed tomography (CT), and assessed the efficacy of VTE prophylaxis (fondaparinux and enoxaparin). At our hospital, 189 patients (225 knees) underwent TKA between April 2007 and October 2011. The 225 knees were divided into a control group with no VTE prophylaxis (31 cases), a fondaparinux group (107 cases), and an enoxaparin group (87 cases). Contrast-enhanced CT screening for VTE was performed in all cases on day 5 or 6 after TKA. D-dimer levels were measured on day 5 after TKA, and were significantly lower in the fondaparinux (9.8 ± 3.8) and enoxaparin groups (9.4 ± 4.9) than in the control group (15.6 ± 9.8) (p ＜ 0.001). However, no statistically significant difference in the incidence of VTE was observed among the groups (control, 61.3%;fondaparinux, 49.5%;enoxaparin, 50.6%). Prophylaxis was not effective for the prevention of VTE as detected by contrast-enhanced CT after TKA. CT should be performed after TKA, even when VTE prophylaxis is used.

The medial meniscus is a secondary stabilizer of anterior tibial translation in anterior cruciate ligament (ACL)-deficient knees. ACL reconstruction effectively restores an increased anterior tibial translation in the ACL-deficient knee. However, knee osteoarthritis sometimes develops in ACL-reconstructed patients during a long-term follow-up period. We hypothesized that the medial meniscal position would be different between the ACL-deficient and reconstructed knees. The aim of this study was to investigate pre-operative and postoperative location of the medial meniscus in patients who underwent ACL reconstruction. ACL-reconstructed knees (28 knees) and normal knees (27 knees) were investigated. Medial tibial plateau length (MTPL) and medial tibial plateau width (MTPW) were determined using radiographic images. Magnetic resonance imaging (MRI)-based medial meniscal length (MML), medial meniscal width (MMW), and medial meniscal extrusion (MME) were measured. Postoperative change in the MML, MMW, and MME were evaluated and compared with those in normal knees. No significant differences between the ACL-deficient (pre-operative) and normal groups were noted. The ACL-reconstructed (postoperative) group showed an increase in the MML, in the percentage of the MML (%MML = 100 MML/MTPL), and in the MME. Significant differences between postoperative and normal groups were observed in the MML, %MML, and MME. MMW and MMW percentage (100 MMW/MTPW) were similar in all groups. The anteroposterior length and radial extrusion of the medial meniscus increased after ACL reconstruction. Transposition of the medial meniscus may be a possible cause of developing further degenerative knee joint disorders after ACL reconstruction.

Anatomic double-bundle anterior cruciate ligament (ACL) reconstruction can restore the function and kinematics of the knee in ACL-deficient patients. Several outside-in drilling systems for accurate femoral tunnel creations have been developed. However, the femoral tunnel creation at the lower position of the intercondylar notch can be difficult in a usual leg position with the knee flexed at 90° without varus stress. This technical note describes that the figure-of-nine leg position provides a better arthroscopic view to safely clean up the ACL femoral footprint located at the lower area of the lateral intercondylar wall. This position is useful to create the optimal femoral tunnels using the outside-in drilling technique, without damaging the lateral meniscus posterior root, lateral tibial eminence, and supplemental fibers that bridge the gap between the lateral meniscus and the ACL tibial insertion.

Meniscus repair can restore meniscal function that transfers the axial compressive force to circumferential tensile strain. However, few reports have investigated the relationship between concurrent meniscus repair with acute anterior cruciate ligament (ACL) reconstruction and postoperative meniscal position. This study aimed to evaluate medial meniscal size and clinical results in patients who underwent ACL reconstruction and concomitant all-inside medial meniscus repair.Twenty patients underwent ACL reconstruction and concurrent medial meniscus repair of a peripheral longitudinal tear using the FasT-Fix meniscal repair device. Medial tibial plateau length (MTPL) and width (MTPW) were determined by radiographic images. We evaluated the Lysholm score, anteroposterior instability, meniscal healing and magnetic resonance imaging (MRI)-based medial meniscal length (MML) and width (MMW). Correlations between MRI-based meniscal size, radiographic measurement and height were investigated.All patients showed complete healing of the repaired meniscus in arthroscopic evaluation. However, one patient needed a subsequent meniscus repair during the follow-up period. Lysholm score and anteroposterior instability improved significantly. A better correlation was observed between MMW and MTPW than between MML and MTPL. Concurrent all-inside medial meniscus repair with ACL reconstruction significantly increased MML percentage (%MML) (100 MML/MTPL) but did not affect MMW percentage (%MMW) (100 MMW/MTPW).Concurrent all-inside medial meniscus repair with ACL reconstruction had satisfactory clinical results. %MML was increased by concurrent medial meniscus repair without affecting %MMW. Our results suggest that medial meniscus repair associated with ACL reconstruction may restore meniscal function by adjusting the anteroposterior length of the torn medial meniscus.

Physiologic mechanical stress stimulates expression of chondrogenic genes, such as multifunctional growth factor CYR61/CTGF/NOV (CCN) 2 and alpha 1(II) collagen (COL2A1), and maintains cartilage home-ostasis. In our previous studies, cyclic tensile strain (CTS) induces nuclear translocation of transforming growth factor (TGF)-beta receptor-regulated Smad2/3 and the master chondrogenic transcription factor Srytype HMG box (SOX) 9. However, the precise mechanism of stretch-mediated Smad activation remains unclear in transcriptional regulation of CCN2 and COL2A1. Here we hypothesized that CTS may induce TGF-beta 1 release and stimulate Smad-dependent chondrogenic gene expression in human chondrocytic SW1353 cells. Uni-axial CTS (0.5 Hz, 5% strain) stimulated gene expression of CCN2 and COL2A1 in SW1353 cells, and induced TGF-beta 1 secretion. CCN2 synthesis and nuclear translocalization of Smad2/3 and SOX9 were stimulated by CTS. In addition, CTS increased the complex formation between phosphorylated Smad2/3 and SOX9. The CCN2 promoter activity was cooperatively enhanced by CIS and Smad3 in luciferase reporter assay. Chromatin immunoprecipitation revealed that CTS increased Smad2/3 interaction with the CCN2 promoter and the COL2A1 enhancer. Our results suggest that CTS epigenetically stimulates CCN2 transcription via TGF-beta 1 release associated with Smad2/3 activation and enhances COL2A1 expression through the complex formation between SOX9 and Smad2/3.

Loose fragments in osteochondritis dissecans (OCD) of the knee require internal fixation. On the other hand, loose fragments derived from spontaneous osteonecrosis of the knee (SONK) are usually removed. However, the difference in healing potential between OCD- and SONK-related loose fragments has not been elucidated. In this study, we investigated proliferative activity and redifferentiation potential of normal cartilage-derived and loose fragment-derived chondrocytes. Cells were prepared from normal articular cartilages and loose fragment cartilages derived from knee OCD and SONK. Cellular proliferation was compared. Redifferentiation ability of pellet-cultured chondrocytes was assessed by real-time PCR analyses. Mesenchymal differentiation potential was investigated by histological analyses. Positive ratio of a stem cell marker CD166 was evaluated in each cartilaginous tissue. Normal and OCD chondrocytes showed a higher proliferative activity than SONK chondrocytes. Chondrogenic pellets derived from normal and OCD chondrocytes produced a larger amount of safranin O-stained proteoglycans compared with SONK-derived pellets. Expression of chondrogenic marker genes was inferior in SONK pellets. The CD166-positive ratio was higher in normal cartilages and OCD loose fragments than in SONK loose fragments. The OCD chondrocytes maintained higher proliferative activity and redifferentiation potential compared with SONK chondrocytes. Our results suggest that chondrogenic properties of loose fragment-derived cells and the amount of CD166-positive cells may affect the repair process of osteochondral defects.

Introduction Injuries to the medial meniscus (MM) posterior root lead to accelerated cartilage degeneration of the knee. An anatomic placement of the MM posterior root attachment is considered to be critical in transtibial pullout repair of the medial meniscus posterior root tear (MMPRT). However, tibial tunnel creation at the anatomic attachment of the MM posterior root is technically difficult using a conventional aiming device. The aim of this study was to compare two aiming guides. We hypothesized that a newly-developed guide, specifically designed, creates the tibial tunnel at an adequate position rather than a conventional device. Materials and methods Twenty-six patients underwent transtibial pullout repairs. Tibial tunnel creation was performed using the Multi-use guide (8 cases) or the PRT guide that had a narrow twisting/curving shape (18 cases). Three-dimensional computed tomography images of the tibial surface were evaluated using the Tsukada's measurement method postoperatively. Expected anatomic center of the MM posterior root attachment and tibial tunnel center were evaluated using the percentage-based posterolateral location on the tibial surface. Percentage distance between anatomic center and tunnel center was calculated. Results Anatomic center of the MM posterior root footprint located at a position of 78.5% posterior and 39.4% lateral. Both tunnels were anteromedial but tibial tunnel center located at a more favorable position in the PRT group: percentage distance was significantly smaller in the PRT guide group (8.7%) than in the Multi-use guide group (13.1%). Discussion The PRT guide may have great advantage to achieve a more anatomic location of the tibial tunnel in MMPRT pullout repair. Level of evidence III.

The meniscus is a fibrocartilaginous tissue that plays an important role in controlling complex biomechanics of the knee. A perimeniscal capillary plexus supplies the outer meniscus, whereas the inner meniscus is composed of avascular tissue. Anti-angiogenic molecules, such as chondromodulin-I (ChM-I) and endostatin, have pivotal roles in preserving the avascularity of cartilage. However, the anti-angiogenic role of ChM-I is unclear in the meniscus. We hypothesized that the inner meniscus might maintain its avascular feature by expressing ChM-I. Immunohistochemical analyses revealed that ChM-I was mainly detected in the inner and superficial zones of the meniscus. On the other hand, endostatin distribution was similar between the inner and outer meniscus. In Western blot, ChM-I was detected only in the inner meniscus, whereas endostatin was equally observed in both inner and outer menisci. In addition, ChM-I concentration of the inner meniscus-derived conditioned medium was higher than that of the outer meniscus-derived medium. ChM-I removal from the inner meniscus-derived medium and functional blocking of ChM-I significantly increased endothelial cell proliferation. In this study, we demonstrated that the inner meniscus contained larger amounts of ChM-I, and that the inner meniscus-derived ChM-I inhibited endothelial cell proliferation. Our results suggest that ChM-I may be a key anti-angiogenic factor for maintaining the avascularity of the inner meniscus.