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Managing Collateral Ligament Tears of the Knee

Robert J. Meislin, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 24 - NO. 3 - MARCH 96


In Brief: Medial collateral ligament and lateral collateral ligament (LCL) tears are common sequelae of varus or valgus knee injuries. Assessment, focusing on the physical exam, requires a high degree of suspicion for associated cruciate ligament, meniscus, and posterolateral or posteromedial corner injuries. Nonoperative treatment consisting of RICE, pain modalities, activity modification, and protection with a hinged brace is standard for most injuries. Grade 3 LCL tears usually require surgery. Functional rehabilitation begins immediately. Return to play is generally allowed when the player has regained 90% of usual strength.

Hits to the outside or inside of the knee, common in contact sports, are the mechanism of medial and lateral collateral ligament injuries. Diagnosis and treatment are effectively handled in the office as long as thorough physical tests and radiographs are done to rule out more serious associated injuries such as cruciate ligament tears, growth plate disruptions, and fractures.

Case Report

A 20-year-old college defensive lineman was hit from the outside of his right knee during a pileup at the line of scrimmage.

On the field, the player reported immediate pain over the inner knee. He did not recall any twisting motion at the time of injury. Evaluation on the sidelines produced negative Lachman and anterior drawer tests. Moderate valgus laxity was noted at 25° flexion; no valgus laxity was present at 0° extension. Swelling was minimal, but the knee was tender along the medial collateral ligament (MCL), especially at the medial femoral epicondyle. Radiographs taken at the stadium were normal.

The patient was diagnosed as having a grade 2 MCL tear. The mechanism of injury was a pure valgus load without associated rotation. The patient's knee was placed in a compression wrap over which ice and a knee immobilizer were applied. Crutches were prescribed, and the patient was advised to begin weight bearing as tolerated. The player was asked to report to the training room the next day to start physical therapy. Over the next several weeks the player progressed with therapy and returned to play after 4 weeks.

Confirm Collateral Tears

Questioning the patient about the mechanism of injury provides important clues about possible MCL or lateral collateral ligament (LCL) injuries. The mechanism of MCL injury described in the case report—a valgus load without rotation—is fairly common in contact sports such as football. Though not as common, LCL injuries often result from a pure varus load as occurs when the inside of the player's knee takes a hit.

When evaluating possible MCL or LCL injuries, the physician locates the injury site by palpating the medial and lateral femoral epicondyles, the joint line, and the proximal medial tibia and fibular head (figure 1). Interstitial tears may be tender along the entire course of the injured ligament. For the MCL exam, the leg should be positioned at 0° and 25° of flexion. Tenderness at the medial femoral epicondyle often signifies an avulsion injury of the MCL's origin; tenderness at the proximal medial tibia suggests an injury at its insertion. The LCL can be appreciated with the leg placed in the figure-4 position (figure 2).

[FIGURE 1]

Determining the degree of injury guides treatment and return-to-play decisions. Qualitatively, the injuries are classified as minimal, partial, and complete. A minimal tear produces little joint laxity because few fibers are torn; swelling and tenderness are noted over the ligament. In partial tears, up to two thirds of the ligament is torn. Moderate laxity is seen with partial tears. Complete tears are accompanied by the greatest degree of laxity; those of the MCL involve its superficial and deep layers (figure 1).

[FIGURE 2]

Quantitative grading is based on results of stress testing. To determine the degree of joint-space opening, the physician applies valgus or varus stress to the knee in neutral tibial rotation at full extension (0°), repeating the procedure with the knee in 25° flexion (figure 3). The posterior capsule is relaxed in 25° flexion, allowing easier assessment of isolated MCL and LCL injuries. Grade 1 injury consists of 0 to 5 mm of opening; grade 2, 6 to 10 mm; and grade 3, 11 to 15 mm. The examiner records the grades at full extension and 25° flexion. Treatment is based on an assessment of MCL laxity at both 0° and 25° flexion. The maneuvers are repeated on the opposite knee because physiologic opening to varus stress is often seen at 25° flexion.

[FIGURE 3]

Assessing the quality of the injured ligament's end point during the physical exam is critical—a soft end point indicates a probable grade 3 MCL or LCL tear. Fetto and Marshall (1) classify end points as hard, mushy, or absent.

Rule Out Associated Injuries

Because the mechanism of injury might have involved rotation, the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) must be evaluated by performing Lachman (figure 4a), pivot shift, anterior drawer (figure 4b), and posterior drawer tests (figure 4c). In isolated MCL or LCL injuries, these tests are usually negative. Because the pivot shift requires an intact MCL as a medial buttress to determine whether the ACL is torn, this test may be falsely negative in a patient who has a grade 3 MCL tear and a torn ACL. In the acute setting, before swelling develops, these tests can be performed comfortably. After about 4 hours, swelling sets in and makes the test more difficult to perform.

[FIGURE 4]

Significant knee effusion does not accompany isolated MCL or LCL injuries; however, effusion is common in the presence of ACL tears, peripheral meniscus tears, osteochondral fractures, and patella dislocations. Effusion may not be present in ACL tears that accompany grade 3 MCL tears because the hemarthrosis will escape through the complete MCL tear.

[FIGURE 5] Injury of the cruciate ligament(s) and the posterolateral and/or posteromedial capsule is suspected if joint space opening and a soft end point are apparent on valgus or varus stress at 0°. The posterolateral (arcuate complex) and posteromedial corners should be examined for associated injury (figure 5). The reverse pivot shift test should be performed to determine the integrity of the PCL.

For the LCL injured knee, the peroneal nerve must be assessed and the possibility of a spontaneously reduced knee dislocation must be considered.

Which Diagnostic Tests?

Radiographs are required in all patients who have suspected MCL or LCL injuries. The radiographic series includes anteroposterior, posteroanterior weight-bearing, lateral, and Merchant views. For skeletally immature patients, radiographs help rule out physeal injuries. If no fracture or separation is seen at the physis on an anteroposterior view, separation of the distal femoral epiphysis may be visible on a valgus stress view.

Among active patients who have chronic MCL insufficiency, radiographic findings may indicate calcification at the medial femoral epicondyle (Pellegrini-Stieda lesion). In LCL injuries, a chip fracture of the fibular head may be present. This should be differentiated from the Segond or lateral capsular sign, which denotes an ACL tear with disruption of the anterolateral capsule of the knee. (The lateral capsular sign is a chip fracture of the anterolateral aspect of the tibia where the anterolateral capsule inserts.)

If the patient has joint line pain that continues beyond 4 to 6 weeks and is accompanied by swelling, magnetic resonance imaging (MRI) may help identify a meniscus or cruciate ligament tear. When the knee exam is difficult because of marked guarding and spasm, an MRI may help document the extent of injury.

How the MCL Heals

Treatment for the three grades of isolated MCL injury is nonoperative because the MCL exhibits good healing response. Grade 3 injuries are more likely to be associated with other injuries that require surgery. Amiel et al (2) describe healing differences between the MCL and the ACL. On a cellular level, cells within the MCL resemble fibroblasts (rod to spindle shaped) whereas cells within the ACL resemble fibrocartilage cells (round to oval). The MCL cells are longer, allowing greater proximity to the ligament's collagen fibers. The fibers increase healing, and their presence is associated with healing. In addition, the crimp pattern that allows the MCL to lengthen or shorten contrasts with the relatively static length of the ACL, which has about one half the expansibility of the MCL. Also, researchers (3) have found that the ACL has fewer collagen fibers.

Medial collateral ligament healing occurs in three phases:

  • Inflammation. The first phase of healing occurs within 3 days after injury. Inflammatory mediators give way to fibroblasts that produce type III collagen and proteoglycans.
  • Repair and regeneration. The second phase occurs about 6 weeks after injury as type 3 collagen decreases and type I collagen increases. Histologically, collagen fibers are oriented along the longitudinal axis of the MCL and fibroblasts are mature at 6 weeks postinjury (4).
  • Remodeling. Ligament remodeling, the third phase, lasts a year or more after the injury (5). Although mechanical testing of conservatively-treated grade 2 MCL tears tested at 1 year exhibited normal parameters for ultimate load and stiffness (4), Woo et al (6) found that the MCL regains only 50% to 70% of its elasticity and strength by 1 year. As collagen content increases, the healing ligament has a larger cross section than a normal ligament (6).

Grade 1 and 2 MCL injuries may heal more quickly than grade 3 injuries, according to the results of an animal study (4).

The Treatment Plan

Conservative management consisting of rest, ice, compression, and elevation (RICE) is the mainstay of care for MCL injuries. Nonsteroidal anti-inflammatory drugs (NSAIDs) are prescribed for pain relief; however, their effect on ligament healing remains controversial (7). To protect the healing ligament, the knee is placed in a short, hinged knee brace that blocks 20° of terminal extension but allows full flexion. Modalities may be added to provide additional pain relief and to hasten healing; these may include ultrasound, phonophoresis, cold whirlpool, ice, and electrical stimulation.

Weight bearing is allowed as tolerated for grade 1 and 2 MCL tears. Pain abates after 3 to 5 days in grade 1 MCL injuries but may continue for up to 2 weeks in grade 2 MCL injuries. For grade 3 tears, initial non-weight-bearing is indicated and the patient advances to partial weight bearing by the second week after injury. By 4 weeks the patient should be fully weight bearing.

Early functional rehabilitation includes range-of-motion and quadriceps strengthening exercises. Range-of-motion exercises are important for ligament healing. Numerous studies (8,9) report that immobilization significantly diminishes ultimate load capacity of the MCL and increases osteoclastic activity at the tibial MCL insertion sites.

The day after injury the patient begins quadriceps isometric strengthening exercises, straight-leg raises, and cocontraction exercises of the hamstrings and quadriceps with the knee flexed 20° and heel pressure directed toward the floor or bed. Closed kinetic chain exercises are implemented and include minisquats, toe raises, leg presses, cycling, and activities with an exercise band. The bicycle seat is initially raised and gradually lowered as the patient's knee flexion improves. Once the patient achieves 90° knee flexion, passive resistance exercises for the quadriceps and hamstrings can be added.

Return-to-Play Strategy

After 4 to 6 weeks of rehabilitation, patients who have grade 1 and 2 MCL injuries may no longer need the brace and may return to sports if they can perform various functional tests: one-legged hopping (both vertical and horizontal), running shuttles, skipping rope, trampoline jumping, using a balance board, and climbing stairs. Linton and Indelicato (10) allow forward running when the injured knee achieves 60% of its normal strength. Agility drills and sprinting are started when 80% strength is achieved on isokinetic testing. When 90% of normal strength is attained, the patient can return to contact drills.

Reider et al (11) outlined a running program designed to replicate football activities. It can be used as a functional test once full motion is regained. It includes a 1-mile jog, successively faster 80-yd sprints, and cutting drills at increasingly faster speeds. The player is allowed to return to practice once he or she is able to complete the entire program in one session with minimal pain and has 90% normal strength of the injured knee.

Grade 3 MCL tears, however, may take as long as 8 to 12 weeks to heal enough to return to activity. Indelicato et al (12), in a report on the nonoperative treatment of grade 3 MCL tears in football players, noted that the average time from injury to return to football was 9.2 weeks. Linton and Indelicato (10) allow the players who have such injuries to return to play when the knee demonstrates 80% strength by isokinetic testing, satisfactory performance on noncontact agility drills, and no medial knee pain with valgus stress.

If a patient fails to progress because of increased pain, persistent swelling, or limited range of motion, a meniscus or cruciate ligament tear must be suspected. Though prophylactic brace use is controversial, after rehabilitation a player may consider returning to sports wearing a hinged knee support that does not preload the MCL. The player may need to wear the brace for several months.

Does LCL Treatment Differ?

Isolated LCL tears are rare, which may explain why there is little basic science or clinical research on their healing. The LCL heals more slowly than the MCL; this may reflect differences in collagen fibers per unit area. Most clinicians would agree that grade 1 and 2 LCL tears should be managed nonoperatively with a protective hinged knee brace, ice, compression, and weight bearing as tolerated.

Rehabilitation for patients who have LCL tears is similar to the protocol described for MCL injuries: functional activities and closed kinetic chain exercises. Knee brace protection on return to play at approximately 8 weeks is recommended.

Grade 3 LCL tears probably are best managed operatively because grade 3 LCL injuries inevitably involve the posterolateral corner of the knee (arcuate complex and popliteus). Kannus (13) reported satisfactory results with nonoperative treatment for grade 2 LCL injuries, but unsatisfactory results with such treatment for grade 3 LCL tears. The type of operation—repair or reconstruction—will often not be decided until the LCL is visualized during surgery.

Back On Solid Ground

Though collateral ligament injuries often aren't as devastating as cruciate ligament injuries, sports-related forces are complex and can produce associated injuries that are more serious. These factors elevate the importance of performing a thorough series of physical tests and radiographs to document the full extent of injury.

When an isolated collateral ligament injury is confirmed, the physician's close involvement in the patient's rehabilitation program complements the ligament's natural healing abilities.

References

  1. Fetto JF, Marshall JL: Medial collateral ligament injuries of the knee: a rationale for treatment. Clin Orthop 1978;May(132):206-218
  2. Amiel D, Billings E Jr, Akeson W: Ligament structure, chemistry, and physiology, in Daniel DM, Akeson WH, O'Connor JJ (eds): Knee Ligaments: Structure, Function, Injury, and Repair. New York City, Raven Press, 1990, pp 77-91
  3. Hart RA, Woo SL, Newton PO: Ultrastructural morphometry of anterior cruciate and medial collateral ligaments: an experimental study in rabbits. J Orthop Res 1992;10(1):96-103
  4. Laws G, Walton M: Fibroblastic healing of grade II ligament injuries: histological and mechanical studies in the sheep. J Bone Joint Surg (Br) 120218;70(3): 390-396
  5. Fu F, Harner C, Johnson D, et al: Biomechanics of knee ligaments: basic concepts and clinical application, in Schafer M (ed): Instructional Course Lectures, Volume 43. Chicago, American Academy of Orthopaedic Surgeons, 1994, pp 137-148
  6. Woo SL, Inoue M, McGurk-Burleson E, et al: Treatment of the medial collateral ligament injury. II: Structure and function of canine knees in response to differing treatment regimens. Am J Sports Med 120217;15(1):22-29
  7. Dahners LE, Gilbert JA, Lester GE, et al: The effect of a nonsteroidal anti-inflammatory drug on the healing of ligaments. Am J Sports Med 120218;16(6):641-646
  8. Tipton CM, James SL, Mergner W, et al: Influence of exercise on strength of medial collateral knee ligaments of dogs. Am J Physiol 1970;218(3):894-902
  9. Woo SL, Gomez MA, Sites TJ, et al: The biomechanical and morphological changes in the medial collateral ligament of the rabbit after immobilization and remobilization. J Bone Joint Surg (Am) 120217;69(8): 1200-1211
  10. Linton R, Indelicato P: Medial ligament injuries, in DeLee JC, Drez D Jr (eds): Orthopaedic Sports Medicine: Principles and Practice. Philadelphia, WB Saunders Co, 1994, pp 1261-1274
  11. 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(4):470-477
  12. Indelicato PA, Hermansdorfer J, Huegel M: Nonoperative management of complete tears of the medial collateral ligament of the knee in intercollegiate football players. Clin Orthop 1990;Jul(256):174-177
  13. Kannus P: Nonoperative treatment of grade II and III sprains of the lateral ligament compartment of the knee. Am J Sports Med 120219;17(1):83-88

Dr Meislin is an orthopedic surgeon at Phoenix Orthopedic Group, PC, in Phoenix, Arizona. He is a member of the National Football League Physician's Society and the Arthroscopy Association of North America. Address correspondence to Robert Meislin, MD, Phoenix Orthopedic Group, 2620 N 3rd St, Suite 100, Phoenix, AZ 85004.


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