Medial knee instability is a serious knee injury that is common with cruciate ligament tears and multiple ligament knee injuries. There are varying degrees of medial instability with respect to pathologic axial rotation and valgus laxity. Treatment of medial instability must address all components of the medial instability pattern which include the medial and posteromedial capsule, the posterior oblique ligament, the superficial medial collateral ligament (MCL), and the semimembranosus insertion sites, as well as other structural knee injuries that are present. The successful treatment of posterior cruciate ligament and anterior cruciate ligament (ACL) injuries depends upon recognition and treatment of the associated medial side injuries.
This issue of Sports Medicine and Arthroscopy Review is dedicated to the evaluation and treatment of medial instability of the knee. It has been an honor to work with this distinguished group of contributing authors who are experts in the evaluation and treatment of medial instability of the knee.
Authors LaPrade, Kennedy, Wijdicks, and LaPrade present the anatomy and biomechanics of the medial side of the knee, and their importance to surgical reconstruction. The authors discuss that in order to reconstruct the medial knee to restore the original biomechanical function of its ligamentous structures, a thorough understanding of its anatomic placement and relationship with surrounding structures is required. To restore the knee to normal kinematics, the diagnosis and surgical approach have to be aligned to successfully reconstruct the area of injury. Three important ligaments maintain primary medial knee stability: the superficial medial collateral ligament, the posterior oblique ligament, and the deep medial collateral ligament. It is important not to exclude the assistance that other ligaments of the medial knee provide, including support of patellar stability by the medial patellofemoral ligament and multiligamentous hamstring tendon attachments. Valgus gapping and medial knee stability is accounted for collectively by every primary medial knee stabilizing structure.
Drs Kurzweil and Craft discuss the physical examination and imaging studies for evaluating medial side knee injuries. The authors emphasize that 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. The authors discuss the importance of magnetic resonance imaging, stress radiography, and ultrasound combined with physical examination for the evaluation of medial knee injuries.
Drs Taylor and Roth address the topic of management of acute isolated medial posteromedial instability of the knee. Taylor and Roth present the idea that medial-sided knee injuries are very common, and that the medial collateral ligament is the most commonly injured ligament of the knee. Injuries to the medial side of the knee can occur in isolation or concomitant with other knee ligament injuries. Isolated grade I and II injuries have been typically treated nonoperatively with excellent results. Isolated grade III injuries, however, are less common and more controversial. Although some recent literature has shown acceptable results with nonoperative treatment of isolated grade III injuries, most authors recommend surgical treatment. The authors emphasize that a variety of surgical techniques have been described, all with favorable outcomes. The surgeons’ choice of treatment method should be based on injury pattern with the goal of regaining valgus and anteromedial rotator stability of the knee.
Drs Wascher, Menzer, and Treme address surgical treatment of medial instability of the knee. The authors discuss several MCL reconstruction options, and outline the authors’ preferred MCL reconstruction surgical technique.
Drs Medvecky and Tomaszewski present the topic of management of acute combined ACL medial posteromedial instability of the knee. The vast majority of these combined medial-sided injuries are treated nonoperatively with delayed reconstruction of the ACL injury in athletically active individuals. The MCL and associated medial structures are carefully assessed on physical examination and classification of the injury is based upon abnormal limits of joint motion. This information aids the surgeon in selecting the appropriate treatment plan in this combined ligament injury pattern.
Drs West and Jiang present the topic of management of chronic combined ACL medial posteromedial instability of the knee. The authors state that the medial collateral ligament is the most commonly injured ligament in the knee. High-grade medial collateral injuries are associated with injuries to the posteromedial structures of the knee. Chronic medial-sided instability is rare due to the intrinsic capacity of the medial ligamentous structures to heal. However, when combined with ACL deficiency, significant anterior, valgus, and rotatory laxity of the knee occurs. West and Jiang further discuss the important biomechanical, clinical, and surgical considerations in the management of chronic combined ACL, medial, and posteromedial instability of the knee.
Dr Stannard presents his experience with evaluation and treatment of medial instability of the knee emphasizing that medial knee ligament injury and instability has frequently been treated by bracing and physical therapy. This has worked well in many instances and patients have been able to resume preinjury activities. However, there is a subset of patients that remain unstable when treated with conservative measures. A critical question we face is why these knees fail when the majority heal well and regain function. What are the differences that lead to failure and how can surgeons recognize these differences and determine which patients will benefit from primary surgical repair or reconstruction? This article addresses these questions.
Fanelli and Fanelli discuss management of chronic combined PCL medial posteromedial instability of the knee. This article emphasizes that currently, there is no collective consensus on the most effective treatment method for medial collateral ligament injuries with or without associated structural deficiencies. An in-depth understanding of relevant anatomic structures and diagnostic tools is critical for determining an appropriate treatment strategy. This manuscript presents an overview for management of chronic combined posterior cruciate ligament and posteromedial instability of the knee, and the results of treatment within the context of the posterior cruciate ligament-based multiple ligament injured knee, and emphasizes the point that recognition and correction of posteromedial instability is the key to successful posterior cruciate ligament reconstruction in combined posterior cruciate ligament posteromedial instability.
Drs Sekiya, Weber, and Kopydlowski present the topic of nonsurgical management and postoperative rehabilitation of medial instability of the knee. The authors state that the decisions regarding the treatment of medial knee injuries must take into account the severity of injury to the entire knee, the chronicity of the injury, and the patient goals and activity level. The treatment and rehabilitation of the medial structures of the knee is largely reliant on the healing potential of these structures. Studies have shown that these medial, extra-articular ligaments may possess the ability to heal by both intrinsic and extrinsic properties. The goals of nonoperative treatment should include healing of the injured medial structures while controlling edema, restoring full knee motion, and preserving muscle strength. In cases of continued medial instability after an isolated grade III injury or in cases of combined multiligamentous knee injuries, the medial structures of the knee may be treated operatively with repair or reconstruction. The goals of rehabilitation following surgical intervention are the same as for nonoperative treatment; however, the progression of activity is more gradual to allow for repaired or reconstructed tissue to heal. If the objectives of early edema control, restoration of knee motion, gradual resumption of weight-bearing, and return of muscle strength are followed, patients should return to full activity following medial injuries to the knee.
Drs Koh and Smyth present the surgical and nonsurgical outcomes of medial knee injuries. The authors indicate that many clinical studies have been written on the treatment of medial-sided knee injuries, however, the vast majority are isolated case series of surgical or nonoperative treatment regimens, and only a few randomized prospective clinical trials can be found in the literature that compare different treatment modalities. Comparison of these treatments is challenging due to the variety of medial-sided structures that can be involved, the multiple different approaches to treatment, and the variability of how objective and subjective clinical outcomes are reported. This paper reports on the injuries by extent and type of anatomic structures damaged including partial medial-sided injuries, completed isolated medial-sided knee injuries, and combined injuries. In general, most authors agree that isolated partial or complete MCL injuries can be treated nonoperatively with a brace and early motion with good clinical outcomes. Prospective, randomized trials support nonoperative treatment of the MCL in combined ACL-MCL injuries. Knee dislocations and posterior medial corner injuries appear to have better results with surgical management including reconstruction. Multiple reconstructive techniques have been described for chronic injuries, but it is difficult to compare their results.
The purpose of this issue of Sports Medicine and Arthroscopy Review is to provide experienced knee surgeons, general orthopedic surgeons, fellows, residents, medical students, and other health care professionals with an interest in medial knee injuries, an overview for the evaluation, nonsurgical, and surgical management of these complex injuries.