Christian Lattermann and Darren L. Johnson
DEFINITION
A medial collateral ligament (MCL) injury usually is the result of a valgus stress on the knee.
Forced external rotation injuries with a valgus component also have been described as a mechanism that can disrupt the MCL.
While the direct valgus force is more likely to injure the superficial MCL, external rotation and valgus stress often causes additional injuries to the deep MCL, the anterior cruciate ligament (ACL), the posteromedial corner, or the posterior oblique ligament.
The most common combined injury is an ACL and MCL injury, followed by meniscus injuries.
ANATOMY
The medial side of the knee can be divided into three layers: superficial (I); intermediate (II); and deep (III).
Layer I: the crural fascia extending from the quadriceps fascia into the tibial periosteum
Layer II: the superficial medial collateral ligament (SMCL) and the medial patellofemoral ligament (MPFL)
Layer III: the deep MCL (ie, the meniscotibial and meniscofemoral ligaments) and the posteromedial corner (ie, semimembranosus and posterior oblique ligament [POL])
The superficial MCL originates from the medial femoral epicondyle. It inserts approximately 4 to 6 cm distal to the medial joint line and can be divided into an anterior and a posterior portion. The anterior portion tightens in flexion; the posterior portion tightens in extension.
The deep MCL tightens in knee flexion and is lax in full knee extension.
The posteromedial corner provides rotational stability to the medial side of the knee. Injuries to these structures cause anteromedial rotatory instability.
The semimembranosus has five main attachments to the posterior capsule of the knee:
Pars reflexa, attaching directly to the proximal medial tibia
Direct arm, attaching to the posteromedial tibia
Insertion to the proximal medial capsule
Attachment to the POL
Attachment to the popliteus aponeurosis
PATHOGENESIS
The typical mechanism for an MCL injury is a valgus stress acting on the knee joint with the foot planted. This mechanism often leads to a disruption of the deep and superficial MCL.
If an external rotational component is added, a disruption of additional restraints such as the ACL and the posteromedial corner is likely. In particular, an injury to the POL indicates a significant capsular injury that leads to a higher grade of medial and rotatory instability.3
MCL injuries can be partial or complete. A complete MCL injury involves disruption of the superficial and deep MCL and usually results initially in inability to ambulate.
MCL injuries can be on either the femoral or tibial side. It is important for the treatment algorithm to differentiate whether the tear involves the femoral origin of the MCL or the tibial insertion.
NATURAL HISTORY
Acute isolated MCL injuries usually are treated nonoperatively with protective weight bearing and bracing for 2 to 6 weeks.
In particular, partial tears of the MCL (grade I or II) heal well with conservative treatment.
Complete MCL injuries (grade III injuries) initially can be treated conservatively if they are femoral-based ligament ruptures.3
A complete tibial-sided MCL avulsion with POL extension is less likely to tighten up with nonoperative management and may require repair or reconstruction.
Grade 3 MCL injuries in combination with other ligament injuries of the knee may require acute surgical repair in case of a complete tibial avulsion with POL extension.5
PATIENT HISTORY AND PHYSICAL FINDINGS
A description of the mechanism of injury (eg, valgus mechanism, valgus rotation mechanism) must be elicited.
The examination includes inspection for peripheral hematoma along the medial side of the knee, palpation of hamstrings, joint line (meniscal injury) and the femoral origin and tibial insertion of the MCL stability testing.
Valgus stress at 0 and 30 degrees: grade 1 (0 to 4-mm opening) and 2 (5 to 9-mm opening) injuries usually can be treated nonoperatively; grade 3 (10 to 15-mm opening) injuries are associated with other ligament tears (ie, ACL, POL) in over 75% of cases.
Slocum's modified anterior drawer test: disruption of the deep MCL allows the meniscus to move freely and allows the medial tibial plateau to rotate anteriorly, leading to an increased prominence of the medial tibial condyle.
Anterior drawer test in external rotation: disruption of the MCL alone should not lead to an increased anteromedial translation. An increased anteromedial translation indicates an anteromedial rotatory instability that involves an injury of the posteromedial capsule (eg, POL, semimembranosus attachments, as well as deep MCL).
A thorough examination of the knee should always include the following assessments:
Meniscus: tenderness directly at the joint line is a sensitive sign for a meniscus injury. The McMurray test or a flexion–rotation–compression maneuver may accentuate medial joint line pain, suggesting a medial meniscus tear. (This test may not be helpful in an acute setting.)
ACL: An immediate (within 24 hours) intra-articular effusion after the injury indicates a high likelihood of ACL injury. Positive Lachman test (acute) and pivot shift test (chronic) indicate an associated ACL tear. In the acute or subacute setting, these tests may be difficult to perform. Instrumented laxity testing (KT-1000) may be helpful in these situations. An increased valgus laxity in full extension almost always indicates something more than an MCL injury.
PCL: A positive posterior drawer test indicates a PCL injury. The endpoint is important to assess the grade of the PCL injury.
Patella: The apprehension sign and localized tenderness on the lateral or medial aspect of the patella or the lateral trochlea indicates a possible patella dislocation, which can go hand-in-hand with an intra-articular effusion. Tenderness at the medial femoral epicondyle also can be caused by an avulsion of the MPFL.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs help to assess the bony integrity of the knee joint. They may show indirect signs of ligament injury (eg, Segond fracture), but they usually are not helpful for the diagnosis of an acute MCL injury.
In the case of chronic MCL instability, a Pellegrini-Stieda lesion (bony spur originating at the femoral origin of the MCL, usually visualized on the flexion weight-bearing posteroanterior radiograph) may be present (FIG 1A).
MRI with or without contrast is helpful to identify medial collateral ligament damage.
Edema or MCL disruption can be visualized.
The location and extent of the disruption (femoral vs tibial) can be determined.
The amount of bone bruising can be assessed, and associated pathology (eg, meniscal tears, ACL tears, posteromedial corner injuries) can be visualized.
Arthroscopic examination is a formidable tool to assess the true nature of the MCL injury.
An ipsilateral “drive-through” sign (ie, opening of the medial compartment of more than 10 mm, allowing for complete insertion of the arthroscope into the medial compartment [FIG 1B]) should arouse suspicion for a significant MCL injury that may require repair or reconstruction.
The location of the acute or chronic injury—femoral or tibial—also can be evaluated. Separate inuries of the POL also can be visualized (FIG 1C).
DIFFERENTIAL DIAGNOSIS
Medial meniscus tear
ACL tear
Posteromedial corner injury
Patella dislocation
Pes-anserine bursitis
NONOPERATIVE MANAGEMENT
Grade 1 and 2 Medial Collateral Ligament Sprains
Rest, ice compression, elevation (RICE) for 24 hours or until swelling is controlled
Once swelling is controlled, partial weight bearing, rangeof-motion (ROM) exercises, and electrical stimulation can be started. A simple hinged brace is applied.
Full weight bearing can be allowed once ROM over 90 degrees of flexion as well as motor control of the thigh musculature has beeen demonstrated.2,4
Once full ROM and 80% strength of the opposite side have been achieved, closed kinetic chain exercises, jogging, and treadmill exercise may begin.
In athletes, a return to sport-specific training is safe once 80% of the maximum running speed is achieved.2,4
Return to play depends on the grade of the sprain.
Grade 1: 10 to 14 days
Grade 2: 3 to 4 weeks
Grade 3 Medial Collateral Ligament Sprains
MCL sprains without associated ACL or meniscus tear account for less than 20% of all grade 3 sprains.
The knee is re-evaluated frequently (every 7 to 10 days) to assess whether the MCL “tightens up.” Tibial-sided complete avulsions of the MCL may not heal and require acute surgical repair if they do not tighten up within the first 4 weeks.
It is important to check for combined ACL/MCL tears. Grade 3 MCL tears with POL extension in combination with
FIG 1 • A. Pellegrini-Stieda lesion indicating chronic medial collateral ligament (MCL) insufficiency. B. Arthroscopic ipsilateral medial drive-through sign. The joint space opens more than 10 mm and permits complete passage of the arthroscope into the back of the medial compartment. C. The arthroscopic examination permits direct evaluation of the injured structure, including the posterior oblique ligament (POL) and tibialor femoral-sided deep MCL The meniscus tends to follow the noninjured structure. A proximal meniscal lift-off suggests a tibial-sided tear, whereas a distal lift-off suggests a femoral-sided tear. an acute ACL tear often require surgical repair or even augmentation because of the rotational laxity that results from the POL injury.
RICE is maintained until the swelling is controlled.
0 to 4 weeks: restoration of ROM, quadriceps/hamstring strengths, normal gait pattern, full weight bearing with hinged knee brace
4 to 6 weeks: full ROM, full quadriceps/hamstring strengths, closed kinetic chain exercises, stair-stepper exercise, proprioceptive exercises
6 to 10 weeks: full squatting, jogging, light agility drills, slow return to competition, brace discontinued for non-contact sports
SURGICAL MANAGEMENT
Preoperative Planning
All radiographs and MRIs are reviewed before surgery.
Associated injuries must be addressed at the same time and often determine the sequence of the surgery (PCL before ACL before MCL)
In case of a chronic MCL injury and associated ACL or PCL tears, the appropriate allograft tissue must be available.
Examination under anesthesia must include a full ligamentous examination (ie, Lachman test, pivot shift test, varus/valgus stress test, dial test, anteromedial drawer test).
Positioning
The patient is positioned in the supine position.
We prefer to use an arthroscopic leg holder. This enables the surgeon to sit during the MCL reconstruction and balance the patient's foot on his or her knee to adjust the flexion angle.
The procedure also can be performed on a regular operating table with the patient in the supine position with a bolster positioned under the knee.
Approach
We use the 6to 8-cm mid-medial approach over the posterior aspect of the superficial MCL.
TECHNIQUES
INCISION AND DISSECTION FOR MID-MEDIAL APPROACH
The incision should be centered over the joint line and can be extended proximally or distally, as necessary.
In case of a proximal extension, the incision should be slightly curved posteriorly over the medial femoral epicondyle.
Retraction of the skin exposes the sartorius fascia, which must be split in a longitudinal or T fashion. Underneath the sartorius fascia (layer I), the superficial MCL is exposed.
The posterior border of the superficial MCL and the anterior border of the POL are identified, and a vertical incision is made along this interval, exposing the deep MCL.
This incision can be carried down through the capsule to expose the meniscal attachments. An avulsion of the POL from the posterior capsule may be identified in select cases.
A plane can be developed between the superficial and the deep MCL.
This plane allows for a separate repair of the deep MCL against the POL to tension the POL.
It also exposes the medial tibial plateau and allows for easy placement of a suture anchor for a repair of the deep MCL at the level of the joint line, which is critical.
ACUTE REPAIR OF TIBIAL-SIDED ISOLATED GRADE 3 MCL TEARS
Tibial avulsion is documented arthroscopically by a positive “drive-through” sign (>10 mm of medial opening).
The medial meniscus lifts off from the tibial plateau during this maneuver, revealing the tibial-sided tear of the deep MCL.
A limited direct medial approach is performed through a 5to 6-cm incision along the posterior aspect of the MCL.
The sartorius fascia is divided, which usually exposes acute avulsion of the deep MCL from the tibia. The superficial MCL also usually is torn but can be sharply divided from the deep MCL.
Three or four double-loaded suture anchors are then placed along the medial border of the tibial plateau about 5 mm below the joint line.
The meniscotibial ligament can be secured to the suture anchors, allowing for an excellent repair of the deep MCL along with the coronary ligament and medial meniscus.
The sutures can be left long after the initial knots are tied and also can be used to tie down the superficial MCL (TECH FIG 1).
TECH FIG 1 • Acute suture anchor repair of the deep MCL with imbrication of the capsule. The suture anchors are placed just distal to the joint surface and allow for reefing of the torn deep MCL to the proximal tibia.
AUTOGRAFT RECONSTRUCTION OF ISOLATED CHRONIC MCL TEARS
Reconstruction of the superficial MCL requires stabilization of the central pivot of the knee. Any associated ACL or PCL injury must be addressed simultaneously with or before the MCL reconstruction.
The reconstruction includes repair and tightening of the deep MCL/POL complex, which should be tightened at 0 degrees. The superficial MCL reconstruction should be tightened at 30 degrees of flexion.
The deep MCL and POL can be identified through the midmedial incision and can be retightened using suture anchors, as with the primary repair of the MCL (TECH FIG 2A,B).
Chronic MCL injuries should be augmented with a superficial MCL reconstruction.
Autograft MCL reconstruction can be done using a Bosworth reconstruction.
In the Bosworth reconstruction, a semitendinosus tendon is harvested using the open or closed tendon stripper. The femoral origin of the MCL is identified. A K-wire is inserted into the insertion site, and isometry is tested to avoid a flexion contracture after the superficial MCL repair.
Once the isometric site is identified, the semitendinosus can be routed around a screw and washer femorally and can be attached distally using a staple or bone tunnels. This allows for reconstruction of the posterior and anterior bundles of the superficial MCL (TECH FIG 2C,D).
TECH FIG 2 • A. Medial incision allowing access to freshly avulsed MCL. B. The sartorius fascia is split, and the superficial MCL attachment is recovered. C,D. Reconstruction of the MCL over a femoral screw and washer using a semitendinosus alloor autograft. C. Routing of the semitendinosus tendon and the skin incisions. D. The final tensioned construct and the screw and washer at the origin of the MCL on the medial femoral epicondyle. (Courtesy of Mark D. Miller, MD.)
ALLOGRAFT RECONSTRUCTION OF ISOLATED CHRONIC MCL TEARS
Borden et al1 have described an allograft reconstruction of the MCL.
A double anterior tibialis tendon or a split Achilles or patella tendon can be used for this technique.
The surgical approach is the same as that described for autograft reconstruction.
The origin of the MCL on the medial epicondyle must be identified. The femoral fixation is positioned at the anatomic insertion of the MCL.
Fixation can be achieved in various ways—bone tunnel using a soft tissue screw fixation, bone block using an interference screw fixation, bone trough, or screw and washer fixation.
The distal tibial fixation has to reconstruct the anterior and posterior aspect of the native MCL (TECH FIG 3).
The allograft can be anchored anteriorly and posteriorly along the anatomic attachment sites using an interference screw (as depicted), a screw and washer, or a staple.
Distal Fixation in Chronic Injuries
In chronic MCL injuries, it often is the distal end of the MCL that has failed to heal.
TECH FIG 3 • Double-bundle MCL allograft reconstruction technique using bioabsorbable screw fixation. (Courtesy of Mark D. Miller, MD.)
Using the standard medial approach, the distal end of the MCL often can be identified (TECH FIG 4A).
This attachment can be used in the reconstruction if the length is adequate; if not, it can be sutured to the reconstruction.
The allograft is then fixed femorally (as described earlier) and routed along the course of the superficial MCL (TECH FIG 4B).
The posterior and anterior portions of the superficial MCL can then be individually attached to the tibia.
TECH FIG 4 • A. Medial incision. The chronically disrupted MCL stump can be visualized through the sartorius fascia. B. An Achilles tendon allograft has been sized to fit in a bone trough at the epicondylar origin of the MCL (depth gauge shown in preparation for screw fixation of the bone block). The allograft has been routed along the course of the MCL and fans out to provide the posterior and anterior portion of the MCL. (Courtesy of Mark D. Miller, MD.)
POSTOPERATIVE CARE
The postoperative course is as follows:
0 to 3 weeks: touch-down weight bearing, hinged brace locked in 30 to 90 degrees of flexion, hamstring/quadriceps strengthening in brace
3 to 6 weeks: progress to full weight bearing, ROM free in brace, quadriceps/hamstring strengthening, closed kinetic chain exercises. The repair must be protected.
6 to 12 weeks: the brace is discontinued. Light jogging and stair-stepper exercise are begun.
12 to 18 weeks: progressive return to sports with sportspecific drills and return to play once 90% of quadriceps and hamstring strength and 75% of maximum running speed have been regained.
OUTCOMES
Grade 1 and 2 MCL sprains should be treated nonoperatively. The average time to return to athletic activities is between 19 and 23 days, on average, for grade 1 and 2 injuries, respectively.2
Grade 3 MCL sprains can be treated nonoperatively with good success if several pitfalls are avoided:
Conservative treatment of an isolated Grade 3 MCL injury allows most athletes to return to play after an average of 34 days.2
Tibial-side avulsions of the deep and superficial MCL with POL extension tend to progress toward chronic MCL laxity. Either early surgical treatment or repetitive clinical examination to assess the gradual return of valgus stability over the course of 4 weeks is advisable. If valgus laxity is still present after 4 weeks, surgical treatment is advised.
Concomitant ACL injuries are common and often will result in residual chronic MCL laxity if treated nonoperatively.
COMPLICATIONS
Failure to diagnose associated ligament, meniscal, and articular cartilage injuries
Deep venous thrombosis
Infection
REFERENCES
1. Borden PS, Kantaras AT, Caborn DN. Medial collateral ligament reconstruction with allograft using a double-bundle technique. Arthroscopy 2002;18(4):E19.
2. Giannotti BF, Rudy T, Graziano J. The non-surgical management of isolated medial collateral ligament injuries of the knee. Sports Med Arthr 2006;14:74–77.
3. Indelicato PA. Isolated medial collateral ligament injuries in the knee. J Am Acad Orthop Surg 1995;3:9–14.
4. Reider B, Sathy MR, Talkington J, et al. Treatment of isolated medial collateral ligament injuries in athletes with early functional rehabilitation: a five-year follow-up study. Am J Sports Med 1994;22: 470–477.
5. Wilson TC, Satterfield WH, Johnson DL. Medial collateral ligament “tibial” injuries: indication for acute repair. Orthopedics 2004;27: 389–393.