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Ramp lesions of the medial meniscus and posterior lateral meniscus root tears (LMPRT) can be present simultaneously in up to 8% of patients undergoing anterior cruciate ligament (ACL) reconstruction. The prevalence of these complex and highly unstable meniscal tears increases exponentially with the severity of the injury. The posteromedial capsule (PMC) has often been disregarded in the past when discussing ligamentous and meniscal injuries, but the recent interest in ramp lesions has drawn surgeons' attention to the posteromedial structures of the ACL injured knee. While the meniscocapsular junction is commonly repaired in unstable ramp lesions, in the current literature there is no report regarding proximal PMC lesions, be they in isolation or associated with complex meniscal injuries. We report here two cases of proximal posteromedial capsular lesions associated with medial meniscus instability and posterior lateral root tears after ACL injury. The first case involves a meniscus ramp lesion associated with a proximal PMC tear and a posteromedial fluid collection in the muscle plane on magnetic resonance in a 22-year-old male soccer player. The second case involves a 21-year-old female soccer player who presented with a PMC lesion after hyperextension/valgus knee injury. The capsular lesions were repaired to restore capsular tension and improve medial meniscus posterior horn stability. [ABSTRACT FROM AUTHOR]

Abstract Ramp lesions of the medial meniscus and posterior lateral meniscus root tears (LMPRT) can be present simultaneously in up to 8% of patients undergoing anterior cruciate ligament (ACL) reconstruction. The prevalence of these complex and highly unstable meniscal tears increases exponentially with the severity of the injury. The posteromedial capsule (PMC) has often been disregarded in the past when discussing ligamentous and meniscal injuries, but the recent interest in ramp lesions has drawn surgeons’ attention to the posteromedial structures of the ACL injured knee. While the meniscocapsular junction is commonly repaired in unstable ramp lesions, in the current literature there is no report regarding proximal PMC lesions, be they in isolation or associated with complex meniscal injuries. We report here two cases of proximal posteromedial capsular lesions associated with medial meniscus instability and posterior lateral root tears after ACL injury. The first case involves a meniscus ramp lesion associated with a proximal PMC tear and a posteromedial fluid collection in the muscle plane on magnetic resonance in a 22‐year‐old male soccer player. The second case involves a 21‐year‐old female soccer player who presented with a PMC lesion after hyperextension/valgus knee injury. The capsular lesions were repaired to restore capsular tension and improve medial meniscus posterior horn stability.

The medial collateral ligament (MCL) is the most commonly injured knee ligament. Most will heal well with nonoperative treatment. However, not all medial knee injuries are the same. A detailed physical examination can help determine the severity of the medial-sided injury. When combined with advanced imaging, the examination will delineate damage to associated medial knee structures, including the location of MCL damage, posteromedial capsule injuries, and combined cruciate injuries. Failure to recognize MCL injuries that may be prone to chronic laxity can lead to significant disability, joint damage, and failure of concomitant cruciate ligament reconstructions. Magnetic resonance imaging is the mainstay of diagnostic imaging, with coronal sequences allowing full assessment of the MCL complex. Tangential views aid in the diagnosis of concomitant injuries. Stress radiography can play a role in evaluating MCL healing and subtle chronic laxity. Ultrasonography is also gaining acceptance as a means to assess MCL injuries. Use of a detailed examination and advanced imaging will allow optimal treatment of medial knee injuries and improve clinical outcomes. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to examine the arthroscopic anatomy of posteromedial capsule and magnetic resonance imaging (MRI) findings in internal derangement of the knee joint and to analyze the relationship between popliteal cysts and the posteromedial capsule. Methods: From 2011 to 2012, a prospective study included 194 knees of consecutive arthroscopic surgeries for assorted knee problems. The anatomy of the posteromedial joint capsule was evaluated arthroscopically and divided into three types by the presence of capsular fold and opening: no capsular fold and no opening (type I), capsular fold without opening (type II), capsular fold with opening (type III). The presence and size of popliteal cyst were documented by MRI. Results: Type I was observed in 160 knees (82.5 %), type II in 10 (5.1 %) and type III in 24 (12.4 %). Popliteal cysts were found in 25 knees (12.9 %) by MRI. Of these cases, symptomatic popliteal cysts were identified in 12 knees (6.9 %). On 160 knees demonstrated to be type I, only 3 knees (1.9 %) had popliteal cysts in MRI, 6 knees (60 %) in 10 knees of type II and 16 knees (66.7 %) in 24 knees of type III. Therefore, there was a statistically significant relationship between the type of anatomy in the posteromedial capsule and the popliteal cyst ( p < 0.001). Conclusion: An association between popliteal cyst and arthroscopic anatomy of posteromedial capsule was demonstrated. Comprehensive understanding and knowledge of the arthroscopic anatomy of posteromedial capsule would contribute to the arthroscopic approach in understanding the pathogenesis of popliteal cyst. Study design: Development of diagnostic criteria on basis of consecutive patients. Level of evidence: 2. [ABSTRACT FROM AUTHOR]

Purpose: In longstanding chronic anterior cruciate ligament (ACL) insufficiency, we identified an abnormal movement of the posterior medial meniscal horn, likely due to insufficiency of the posteromedial meniscotibial ligament. Passing from extension to flexion or vice versa, the medial posterior horn slides below the posterior rim of the tibia exposing the tibial plateau. Fixation with suture anchors of the meniscotibial ligament through a posteromedial portal restored normal meniscotibial tension and reduced instability of the meniscal posterior horn. The purpose of the present study was to present the arthroscopic features of posterior medial meniscus instability and to report results following arthroscopic repair. Methods: During the two-year study period, from 2007 through 2008, this arthroscopic feature was detected in 12 patients, 5 patients had failure of a previous ACL reconstruction and 7 patients had delay in ligamentous reconstruction for various reasons. All patients were affected by severe anterior-posterior translation with 11.3 ± 4.3 mm of side-to-side difference at KT-2000 and by associated rotatory laxity with grade 3 of pivot shift. Results: At follow-up of 1 year, the combined ACL reconstruction and fixation of the posteromedial horn showed a reduction in the rotatory and anteroposterior laxity. Conclusions: This study suggests the importance of a proper arthroscopic evaluation of the posterior medial capsule in patients with chronic ACL insufficiency and highlights the potential presence of an unstable posterior horn of the medial meniscus as an indirect arthroscopic sign of peripheral laxity. Level of evidence: Retrospective chart review, Level IV. [ABSTRACT FROM AUTHOR]

The anatomy of the medial collateral ligament (MCL) complex consists of three identifiable passive restraining structures: the longitudinal fibres of the superficial medial collateral ligament (sMCL), the deep medial collateral ligament (dMCL), and the posteromedial capsule (PMC). The purpose of this study was to measure and compare the structural properties of these three individual structures. Eight human cadaveric knees (age 72–89 years, mean=77 years, S.D. 5.3) were harvested and bone–ligament–bone tensile testing specimens prepared. After preconditioning, the specimens were extended to failure at 1000 mm/min in an Instron tensile testing machine. Ligament bundles failed either mid-substance or at their bony attachments. The ligament bundles had maximum loads of 534 N (sMCL), 194 N (dMCL), 425 N (PMC) and failed at 10.2, 7.1, and 12.0 mm mean extension, respectively. The maximum load and linear stiffness of the sMCL were significantly higher than those of the dMCL but not the PMC. The maximum load of the PMC was significantly higher than that of the dMCL; the linear stiffness of the PMC was higher than that of the dMCL but this did not reach statistical significance. The dMCL failed at a significantly lower extension than the other structures. The sMCL bundles that failed at their bony attachment were remounted using a freezing clamp fixture and again extended to failure, resulting in mid-substance failure at 884 N (74% higher). This study has shown that the PMC of the knee has comparable structural properties to the long superficial MCL and the short, deep MCL. In summary, the structural properties of the different component structures of the medial ligament complex indicate possible functional significance. [Copyright &y& Elsevier]