Medial ligament injuries of the knee are often assumed to be only medial collateral ligament (MCL) injuries. However, the medial ligament includes not only the MCL but also posteromedial structures that play a vital role in the stability of the knee. Recent work of LaPrade and colleagues has demonstrated that the posterior oblique ligament (POL) is an important valgus and rotational stabilizer of the knee. The management of the MCL has evolved during the past 30 years. Most isolated MCL injuries are treated conservatively, with a rare role for surgical intervention. However, the treatment of MCL sprains with anterior cruciate ligament (ACL) injury (or any other concomitant ligamentous injury for that matter), along with the timing of ACL reconstruction, continue to be controversial. This chapter describes the anatomy of the medial knee (including the often forgotten posteromedial corner), evaluation of the knee, treatment of medial ligament injuries, and the role of rehabilitation.
History
The history will depend on whether the injury is witnessed by the physician on the sidelines or elicited from the patient in the clinic. Most of these injuries present in the office setting as potentially chronic conditions. A description of the mechanism of injury should be elicited in as much detail as possible. It is important to ascertain when the patient was hurt and how. Typically the injury is the result of a blow to the lateral aspect of the leg or lower thigh. The mechanism may be a result of a clipping injury in football or a noncontact injury from cutting, pivoting, or twisting. Skiers are prone to medial-side injuries, with 60% of skiing knee injuries affecting the MCL. In addition, it is important to ask the patients about pain, onset of swelling, ability to ambulate, the sensation of a “pop,” and the presence of a deformity necessitating a reduction, such as patellar dislocation or a more severe knee dislocation. In addition, a history of knee injuries or surgeries should be elicited because they can cloud an acute knee injury examination.
Physical Examination
Ideally, the examination of the knee should occur at the time of injury before the onset of muscle spasm. However, most of these injuries are examined in the office setting after some time has elapsed after the injury. A thorough knee examination includes observation of the patient’s gait, documentation of the neurovascular status, palpation of the knee for tenderness, swelling, and ecchymosis, and assessment of stability. The physician should follow some basic principles: (1) assess the ligaments and muscles while the patient is as relaxed as possible, (2) perform the physical examination as gently as possible, and (3) examine the uninjured knee before assessing the injured knee.
The patient’s gait should be observed as the patient walks into the room or at some point during the examination. Gait may be misleading, however, because patients with a complete MCL tear may walk with a barely perceptible limp. Hughston and colleagues found that 50% of athletes with grade III injuries could walk into the office unassisted and reported that a complete disruption of the medial compartment can occur “without subsequent significant pain, effusion, or disability for walking.” However, patients with an MCL tear may exhibit a vaulting-type gait in which the quadriceps is activated, allowing stabilization of the medial-sided structures during gait. This gait differs from that of a patient with an ACL or meniscus tear who may walk with a bent knee gait because of pain or an effusion. As with any orthopaedic injury, the neurovascular status of the limb should be assessed. Pedal pulses should be palpated and sensation should be assessed over the dorsum, plantar, and first web space of the foot. If a knee dislocation is a possibility, ankle brachial indices should be performed to evaluate for vascular injury. Compartments should be examined to rule out compartment syndrome. The ability to passive and actively dorsiflex and plantarflex the ankle and great toe should be assessed.
On the skin, the physician should look for edema, effusion, and ecchymosis to help localize the site of injury. It is important to differentiate between localized edema and an intraarticular effusion. Isolated MCL injuries usually have localized swelling. Hemarthrosis of the knee may indicate intraarticular pathology, such as an ACL or peripheral meniscal tear. Severe medial complex injuries with an ACL tear frequently show no evidence of effusion because the capsular rent is large enough to allow extravasation of fluid and blood. If hemarthrosis is present, the examiner should exclude other injuries such as a torn cruciate, patellar dislocation, an osteochondral fracture, and a peripheral meniscal tear. Along with assessment of swelling, palpation of the anatomic sites of attachment can provide clues to the diagnosis. The entire course of the MCL should be palpated from proximal to distal. Pain at the medial femoral epicondyle signifies injury at the femoral insertion of the MCL. With tibial-sided injuries, patients have pain along the proximal tibia around the pes anserine adjacent to the tibial tubercle. Mid-substance tears result in pain at the joint line, and such pain may also present with a medial meniscal injury, posing a diagnostic dilemma. Hughston and colleagues showed that point tenderness can accurately identify the location of injury in 78% of cases, and localized edema can identify a tear in the medial meniscus 64% of the time. A valgus injury that disrupts the MCL may also result in lateral meniscus tears or osteochondral fracture to the lateral femoral condyle or lateral tibial plateau. Therefore a thorough examination of the lateral knee should also be performed.
Valgus stress testing at 30 degrees of knee flexion is still the gold standard for assessing isolated injury to the MCL. This test should be performed with the foot in external rotation because increased instability will be noted if the knee moves from internal to external rotation. To relax the hamstrings and quadriceps muscles, the thigh should rest on the examination table and the foreleg should move freely off the edge of the table at 30 degrees of flexion. The examiner then grasps the ankle and applies a valgus stress with the other hand resting on the medial side of the knee to assess the amount of opening and the quality of the end point compared with the uninjured side. The laxity of the MCL can be recorded based on a grading system or the amount of opening. According to the Noyes classification, 5 to 8 mm of medial opening signifies a significant collateral ligament injury with “impairment of the ligament’s restraining effect.” The grading system has three grades: (1) stress examination produces little to no opening with pain along the line of the collateral ligament; (2) some opening to stress occurs but with a firm end point; and (3) significant opening of the joint occurs with no end point. After assessing the degree of opening, a repeat valgus stress should be performed with the examiner palpating the medial meniscus to assess if it subluxates in and out of the joint, indicative of injury to the meniscotibial ligament.
In addition to valgus testing in flexion, opening of the medial joint should be assessed with the knee in full extension. The cruciate ligaments, POL, posteromedial capsule, and MCL all contribute to knee stability in full extension. Asymmetric joint opening compared with the contralateral side should alert the physician to the possibility of a combined MCL injury with a cruciate tear or posteromedial complex injury. If any increased laxity is observed in full extension compared with the uninvolved knee, it is unlikely that an isolated MCL injury is present; rather, it is likely that the patient has a concomitant injury to the posteromedial capsule and POL in addition to the MCL lesion. The ACL should be assessed with the Lachman test because the pivot shift is difficult to perform as a result of guarding and the loss of the pivot axis with medial instability. In addition, the posterior cruciate ligament and lateral ligamentous structures should be examined. Along with cruciate injury, patellar instability and tearing of the vastus medialis obliquus are associated with laxity in full extension. Hunter and colleagues found 18 of 40 laterally displaceable patellae on stress radiographs in patients with medial-sided injuries and a 9% to 21% incidence of damage to the extensor mechanism with medial ligament injury. In addition to valgus testing at 30 and 0 degrees, the Slocum modified anterior drawer test and an anterior drawer test in external rotation should be performed to assess for medial-sided injuries ( Table 100-1 ).
Imaging
Radiography, arthrography, magnetic resonance imaging (MRI), and arthroscopy can provide information regarding knee injuries. Radiography with anteroposterior, lateral, and sunrise views should be performed for both knees. These radiographs should be evaluated for occult fractures, the lateral capsular sign (Segond fracture), ligamentous avulsions, old Pellegrini-Stieda lesions (i.e., an old MCL injury) ( Fig. 100-1 ), and loose bodies. In adolescent and pediatric patients, stress radiographs help differentiate between physeal and ligamentous injuries.
MRI without contrast is the imaging study of choice for evaluating MCL tears because it is less invasive than other studies and provides detail for lesions of the medial meniscus, superficial MCL, POL, posteromedial complex, and semimembranosus tendon ( Fig. 100-2 ). In addition, MRI is beneficial in assessing injuries to anterior and posterior cruciate ligaments, the meniscus, and osteochondral structures. Loredo and associates showed that intraarticular contrast may help highlight and better define the structures of the posteromedial complex but still concluded that the assessment of the posteromedial complex was difficult. They found that the posteromedial complex was best visualized on coronal and axial images. Indelicato and Linton stated that MRI can provide advantages in four circumstances: (1) when the status of the ACL remains uncertain despite physical examination; (2) when the status of the meniscus is in question; (3) when surgical repair of the MCL is indicated and localization of the tear will help limit the exposure; and (4) when an unexplainable effusion occurs during rehabilitation. However, MRI does not always provide concrete diagnosis, and the clinical examination becomes the deciding factor. Examination after administration of an anesthetic is another tool the physician can use to assess the injury pattern in patients who present long after an injury has occurred or in patients for whom the office examination and MRI do not provide a diagnosis. Upon examination with use of an anesthetic, Norwood and coworkers found that 18% of patients had anterolateral rotatory instability that was not suspected preoperatively. In addition to MRI, arthrograms can be used to evaluate meniscal disease and capsular tearing with extravasation of contrast material. Kimori and colleagues found arthrography to be more useful than arthroscopy in diagnosing tears of the meniscotibial and meniscofemoral ligaments.
With the increased use of MRI, arthroscopy is used infrequently as a diagnostic tool. ACL and meniscal tears may be identified on MRI. Also, it is rare to find an intrasubstance medial meniscal tear in an isolated MCL rupture because meniscocapsular separation occurs, and thus the fulcrum to load the medial compartment and tear the medial meniscus is lost.
Decision-Making Principles
When considering treatment of the MCL, one must remember that most MCL injuries heal reliably with conservative management. For injuries that are chronic or involve the posterior oblique ligament or for concomitant ligamentous injuries, the debate continues regarding nonoperative versus surgical treatment. Other associated injuries or rotational instability resulting from a POL injury may require surgical treatment. Surgical management of chronic laxity of the medial structures can be quite difficult, and therefore anatomic repair of the medial support structures in the acute setting is preferred when indicated. With most MCL injuries, clinical outcomes will be satisfactory after a period of immobilization and recovery of motion and strength, followed by progressive activities. In the small subset of patients with continued pain, instability, or impaired performance, surgical management must be considered.
A review of literature for nonoperative versus operative treatment of complete isolated MCL injuries does not delineate the site of injury. The site of injury may have a role in the functional recovery of patients who place a high demand on their knees. In our practice caring for Division I collegiate athletes, several complete injuries of the MCL off the tibial insertion failed to heal reliably with nonoperative treatment. After recovery, athletes may have varying amounts of valgus knee instability, preventing return to competitive sports and resulting in dysfunction in activities of daily living. Most MCL sprains should be treated nonoperatively. Complete avulsions of the superficial and deep MCL from the tibia with disruption of the meniscal coronary ligament have a poorer prognosis with nonoperative treatment and may be optimally managed with acute surgical repair for improved valgus stability of the knee.
Before proceeding with a treatment plan, it is essential to know the extent of injury. Initially we perform a thorough history and physical examination. With MCL injuries, we assess the grade of injury of the MCL and any associated ligamentous, meniscal, posteromedial corner, or patellar injuries. We obtain radiographs as a routine diagnostic tool to rule out fracture or any signs of chronic medial insufficiency (Pellegrini-Stieda lesion) and chronic ACL deficiency (the deep femoral notch sign, peaked tibial spines, or a cupula lesion). The use of MRI is dependent on the grade of the MCL lesion and associated injury. Isolated grade I or II injuries can be diagnosed with clinical examination and do not require MRI. However, in a grade I or II injury with an indeterminate cruciate examination and effusion, we order an MRI. We also obtain MRI for all grade III injuries because the site of involvement—tibia or femur—is important in our decision making, particularly the extent of injury to the POL and posteromedial capsule. With grade III laxity in full extension and complete involvement of the POL and capsule, avulsion of the posterior horn of the medial meniscus root may be seen ( Fig. 100-3 ) and demands surgical intervention. In addition, most grade III lesions are associated with concomitant ligamentous injuries. Our treatment algorithm is outlined in Figure 100-4 .
Management of grade III injuries is much more controversial. Even with physical examination and advanced imaging, it remains difficult to gauge the extent of damage to the POL and posteromedial capsule in combined injuries. The treatment of grade III MCL sprains has significantly evolved during the past 20 years. The general consensus has been to treat isolated grade III injuries conservatively. We believe that the treatment of grade III injury is dependent not only on the specific location of the MCL rupture but also the degree of laxity on physical examination, as well as the degree of the arthroscopic drive-through sign. The extent of injury and laxity of the injury to the POL and posterior capsule is instrumental in our decision making. Nonoperative management of these injuries may lead to a rotational instability in addition to valgus laxity, which is not well tolerated by athletes involved in pivoting sports. Grade III injuries not only involve complete disruption of its fibers but also are frequently associated with additional ligamentous injuries.
Treatment Options
Management of the MCL and medial-sided knee injuries can be divided into operative and nonoperative approaches. Numerous factors, including the timing, severity, location, and associated injuries such as an ACL tear need to be taken into account when formulating a treatment plan. The MCL has the greatest capacity to heal of any of the four major knee ligaments because of its anatomic and biologic properties. As a result of multiple biomechanical, clinical, and functional studies, the trend has been toward a conservative, nonsurgical method for most MCL injuries.
Grade I and II isolated tears of the MCL generally respond well to nonoperative management. Partial tears are treated routinely with temporary immobilization and protected weight bearing with crutches. Once the swelling subsides, range of motion, resistive exercises, and progressive weight bearing are initiated. Nonsteroidal antiinflammatory drugs can be used to help with pain and swelling. Studies have shown no deleterious effect of nonsteroidal drugs on ligament healing.
Management of grade III injuries remains much more controversial. Even with physical examination and advanced imaging, it remains difficult to gauge the extent of damage to the POL and posteromedial capsule in combined injuries. Nonoperative management of these injuries may lead to a rotational instability in addition to valgus laxity, which is not well tolerated by athletes involved in pivoting sports. Grade III injuries not only involve complete disruption of its fibers but also are frequently associated with additional ligamentous injuries. Recently, posteromedial corner injuries have been recognized as a separate entity from MCL injuries and may need to be addressed more aggressively because of rotational laxity and instability that can result from their injury.
Anatomic medial knee reconstruction has been described recently in the literature. For grade III injuries requiring surgery, the reconstruction techniques addressing the posterior oblique ligament offer improved clinical stability and restoration of knee mechanics.
We treat isolated grade I and II MCL injuries conservatively. In the first 48 hours, we encourage rest and use of ice, compression, and elevation to help reduce swelling. In addition, we have all patients use a hinged knee brace and provide crutches for protected weight bearing. If patients have significant pain and valgus laxity, initially we lock the brace in extension. Once the swelling subsides and pain is improved, we encourage aggressive range-of-motion exercises and straight leg raises with quadriceps exercises. Once the patient has regained full range of motion and ambulation without a limp, use of crutches and the brace can be discontinued. Stationary bicycle and progressive resistive exercises are instituted as tolerated. Once full range of motion and 80% strength of the opposite side have been achieved, closed-chain kinetic exercises and jogging are allowed. Once athletes have achieved 75% of the maximal running speed, sport-specific training is allowed. Return to sports is permitted after the patient has strength, agility, and proprioception equal to the other side. We recommend a functional brace for contact or high-risk sports.
Patients with grade I sprains usually return to sports in 10 to 14 days; because immobilization is temporary, these patients regain strength and motion quickly. However, return to play after grade II sprains is much more variable. With grade II sprains, the period of immobilization can be up to 3 weeks to allow the pain to dissipate. Therefore patients can lose more strength and motion with increased time of immobilization compared with patients with grade I sprains. Patients are allowed to return to play when they have equal strength of both knees and no pain is experienced with valgus stress.
The treatment of grade III MCL sprains has significantly evolved during the past 20 years. The general consensus has been to treat isolated grade III injuries conservatively. We believe that the treatment of grade III injury is dependent not only on the specific location of the MCL rupture but also the degree of laxity on physical examination, as well as the degree of the arthroscopic drive-through sign. The extent of injury and laxity of the injury to the POL and posterior capsule is instrumental in our decision making.
Diagnostic arthroscopy is performed initially to evaluate intraarticular injuries. The medial opening is assessed arthroscopically, termed the “medial drive-through” finding. This part of the examination is critical in that it indicates where the MCL injury is primarily based and where it will be necessary to operate and perform a repair. For femoral-sided MCL injuries, the medial meniscus remains reduced with the tibia upon valgus opening (i.e., a gap forms above the medial meniscus). On the other hand, tibial-sided MCL injuries demonstrate that the medial meniscus remains reduced with the femur on valgus opening (i.e., a gap forms between medial meniscus and tibia, with the medial meniscus lifting off the tibia).
With valgus opening of the knee during arthroscopic examination, it may be observed whether the knee opens posteriorly to the medial meniscus, particularly as the knee is slowly extended with valgus load. If the capsule is exposed with this maneuver posteriorly, the patient has an injury of the POL and posterior medial capsule, which needs to be addressed at the time of surgical correction.
If the injury is acute, medial repair is attempted. For chronic injuries, the medial structures are repaired and reconstructed or augmented.
For acute repair, the origins and insertions of the deep and superficial MCL are evaluated. Typically the lesion is on the tibial side. Isolated femoral-sided lesions often heal reliably without surgical repair.
The surgical approach is a fairly easy one in that the incision is similar to a hamstring harvest incision, except the length of the incision is longer in the proximal direction. The surgical incision is longitudinal between the tibial tubercle and the medial aspect of the knee. This exposure is carried from the inferior margin of the superficial MCL and may be taken proximally to the femoral insertion if required. The sartorial fascia is incised to expose the MCL. The hamstrings are retracted for dissection deeper to the MCL insertion to the tibia.
The initial approach is made from the inferior aspect of the lesion by placing grasping tension sutures in the entire MCL structure. Careful dissection is performed while lifting it off the tibia with a scalpel or periosteal elevator, following its course superiorly and posteriorly. Following the MCL structures superior to the medial joint line and exposing the insertion of the deep MCL results in further dissection.
Repair of the deep MCL insertion is performed by placing multiple suture anchors from posterior to anterior along the tibial joint line; four anchors with double-loaded nonabsorbable sutures are typically used.
Sutures are then passed through the deep and superficial MCL structures and tied down to the tibia while maintaining tension on the grasping sutures placed at the start of dissection. Tying of sutures to the tibial insertion is performed at 30 degrees of flexion with a varus load applied to the knee. The tibial insertion of the superficial MCL is often secured to the tibia with a large fragment screw and spiked-washer construct distally with the grasping sutures.
Posteriorly to the repaired MCL structures, the POL and capsular tissue are reefed from multiple posterior to anterior directed sutures, typically figure-8 sutures or horizontal mattress sutures. The objective is to take the laxity and slack out of the medial POL, which helps tighten the rotational instability caused from the injury.
Chronic medial-sided injuries are also assessed initially with arthroscopy. As previously described, the liftoff test is performed in a valgus maneuver to the knee. If the medial meniscus lifts off the tibia with valgus stress to the knee, we approach reconstruction of the tibial side. If the medial meniscus stays to the tibia with valgus stress to the knee, it is a more femoral-based injury. Surgical exposure and approach is the same as stated previously in the acute repair.
For chronic MCL injury reconstructions, if postoperative stiffness is not a concern or if the patient has an isolated MCL injury, an autograft hamstring tendon is harvested in the same surgical incision. Otherwise, allograft tendon is used for reconstruction.
The deep MCL structures and capsule are repaired to the anatomic origin and insertion of the femur and tibia with suture anchors and double-loaded with nonabsorbable sutures, as described previously for the acute injury repair. The tissue is reefed to remove laxity and slack in the injured structures. Augmentation with the autograft or allograft is performed once this maneuver is complete.
To augment the repair, autograft semitendinosus hamstring is harvested with an open-ended tendon stripper, leaving the distal attachment intact to the tibia at the pes anserine. The muscle tissue is cleaned from the semitendinosus tendon proximally with a large periosteal elevator, and a nonabsorbable whipstitch suture is placed in the free end of the tendon. All accessory attachments of the semitendinosus distally are carefully freed. A Kirschner wire is inserted at the medial epicondyle. The tendon is looped over the wire and the isometry of the tendon is evaluated with the knee in flexion and extension. If the excursion is more than 2 mm, the wire is moved to a position of isometry. Once isometry is confirmed, a large fragment screw and spiked washer are placed provisionally in the femur without fully setting the head at that isometric position of the medial femoral epicondyle. A bone trough is made around the screw shank. The tendon is looped around the screw. The screw is then tightened to the femur with the knee in 30 degrees if flexion, and varus stress is applied to the knee.
A right-angled hemostat is used to create a window in the direct head semimembranosus tendon attachment of the femur posteriorly. The free end of the semitendinosus tendon autograft is then directed posterior and obliquely and pulled through this window, recreating the central arm of the POL. The autograft is sutured to the semimembranosus tendon with use of a nonabsorbable suture.
If an allograft tendon is used, the aforementioned technique is modified, with attachment of the tibial limb of the allograft augment secured to the tibial insertion of the superficial MCL with another large fragment screw and spiked-washer fixation.
For multiple ligamentous knee injuries, the ACL is reconstructed and the medial structures are addressed with the previously described techniques depending on the time from injury.
A case example is that of a 16-year-old high school football player who sustained a contact MCL and ACL injury that was treated operatively in a staged fashion ( Figs. 100-5 to 100-7 ). After treatment, he was allowed full return to contact sports 1 year from injury. Although most femoral-sided tears can be treated successfully with conservative methods, complete tibial-sided avulsions of the deep and superficial MCL, although rare, often heal with residual laxity. In athletes who participate in level I sports, we frequently favor operative repair of these tibial-sided complete avulsions that display retraction of the deep or superficial MCL on MRI (see Fig. 100-8 ). Figures 100-8 and 100-9 highlight a case example of a Division I football player with an isolated tibial-sided complete MCL avulsion with gross laxity and an impressive arthroscopic drive-through sign that was treated surgically.
