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Updated: Feb 26 2024

MCL Knee Injuries

Images
https://upload.orthobullets.com/topic/3010/images/MRI - MCL injury_moved.jpg
https://upload.orthobullets.com/topic/3010/images/valgus stress.jpg
https://upload.orthobullets.com/topic/3010/images/pellegrini stieda.jpg
  • summary
    • A medial collateral ligament (MCL) knee injury is a traumatic knee injury that typically occurs as a result of a sudden valgus force to the lateral aspect of the knee.
    • Diagnosis can be suspected with increased valgus laxity on physical exam but requires MRI for confirmation. 
    • Treatment is generally nonoperative with bracing.  Surgical management may be indicated for high grade injuries in the setting of persistent valgus instability.
  • Epidemiology
    • Incidence
      • most common ligamentous injury of the knee
        • 40% of knee ligament injuries
      • incidence is likely higher than reported
        • low grade injuries can be missed
    • Demographics
      • males > females
      • commonly occur in athletes
        • account of 8% of all athletic knee injuries
        • highest risk in skiing, rugby, football, soccer and ice hockey
  • Etiology
    • Pathophysiology
      • valgus stress is the most common mechanism of injury
        • usually with the knee held in slight flexion and external rotation
      • contact injury
        • more common than noncontact
        • direct blow to the lateral knee with valgus force
        • more often result in high grade / complete ligament disruption than noncontact injury
          • rupture usually occurs at the femoral insertion of the MCL
            • proximal MCL tears have greater healing rates
            • distal MCL tears have inferior healing and residual valgus laxity
      • noncontact injury
        • less common than contact but more common in skiing
        • pivoting or cutting activities with valgus and external rotation force
        • more often result in low grade / incomplete ligament injury
    • Associated conditions
      • anterior cruciate ligament (ACL) tear
        • most common associated injury
          • make up ~95% of injuries associated with nonisolated MCL injury
          • combined ACL-MCL is the most common multiligamentous knee injury
        • presence of hemarthrosis is highly suggestive
        • often associated with high grade MCL injuries
          • grade III > grade II > grade I
      • meniscus tear
        • medial > lateral
        • up to 5% of isolated MCL injuries are associated with meniscus tears
      • Pellegrini-Stieda syndrome
        • calcification at the medial femoral insertion site
        • results from chronic MCL deficiency
  • Anatomy
    • Ligaments of the knee
    • Anatomy
      • superficial MCL
        • located in layer II of the medial knee
          • with posteromedial corner ligaments and medial patellofemoral ligament
        • femoral attachment
          • medial epicondyle
          • 1cm anterior and distal to the adductor tubercle
        • tibial attachment
          • proximal tibia periosteum
          • 4.5cm distal to the joint line
          • deep and posterior to the pes anserinus
      • deep MCL
        • located in layer III of the medial knee
          • with the joint capsule
        • composed of meniscofemoral and meniscotibial ligaments
    • Vascular supply
      • superior medial and inferior medial geniculate arteries
    • Function
      • superficial MCL
        • primary stabilizer to valgus stress
          • at all angles of knee flexion
          • greatest stability contribution at 25 degrees knee flexion (78%)
        • secondary stabilizer to tibial external rotation and anterior/posterior tibial translation
      • deep MCL
        • secondary stabilizer to valgus stress
          • greatest stability contribution at full knee extension
      • other stabilizers of the medial knee
        • static stabilizers
          • posterior oblique ligament
            • resists tibial internal rotation at full knee extension
            • secondary restraint to valgus stress
          • oblique popliteal ligament
          • posterior capsule
        • dynamic stabilizers
          • semimembranosus complex
            • consists of 5 attachments
              • vastus medialis
              • medial retinaculum
              • pes anserine muscle group
                • sartorius
                • semitendinosus
                • gracilis
  • Classification
      • American Medical Association (AMA) Classification
      •  Based on joint laxity alone (described in 1966)
      •  Valgus stress applied with the knee in 30 degrees of flexion
      •  Graded by the amount of medial joint line opening
      •  < 3 mm considered physiologic laxity
      •  Caused confusion and difficulty comparing treatment results
      • Grade I
      • 3-5 mm
      • Grade II
      • 6-10 mm
      • Grade III
      • > 10 mm
      • Hughston Modification of the AMA Classification
      •  Based on joint laxity and injury severity.
      •  Severity graded by the extent of tenderness and quality of the endpoint with valgus stress at 30.
      • Degrees of knee flexion.
      •  Often referred to as "degree" of injury.
      • Grade I
      • Mild
      • First-degree injury
      • Firm endpoint with no joint laxity
      • Stretch injury or few MCL fibers torn (no significant loss of ligament integrity)
      • Grade II
      • Moderate
      • Second-degree injury
      • Incomplete / partial MCL tear
      • Firm endpoint +/- mild increase in joint laxity
      • Some MCL fibers remain intact, generating the firm endpoint
      • Grade III
      •  
      • Severe
      • Third-degree injury
      • Complete MCL tear
      • No endpoint with valgus stress
      • Increased joint laxity (subdivided by degree of joint laxity)
      •     Grade 1+: 3-5 mm
      •     Grade 2+: 6-10 mm
      •     Grade 3+: > 10 mm
  • Presentation
    • History
      • "pop" reported at time of injury
    • Symptoms
      • medial joint line pain
      • difficulty ambulating due to pain or instability
    • Physical exam
      • inspection and palpation
        • tenderness along medial aspect of knee
        • ecchymosis
        • knee effusion
      • ROM and stability
        • valgus stress testing at 30° knee flexion
          • isolates the superficial MCL
          • medial gapping as compared to opposite knee indicates grade of injury
            • 1- 4 mm = grade I
            • 5-9 mm = grade II
            • > or equal to 10 mm = grade III
        • valgus stressing at 0° knee extension
          • medial laxity with valgus stress indicates posteromedial capsule or cruciate ligament injury
      • neurovascular exam
        • saphenous nerve exam
      • evaluate for additional injuries
        • ACL
        • PCL
        • patellar dislocation
        • medial meniscal tear
  • Imaging
    • Radiographs
      • recommended
        • AP and lateral
      • optional view
        • stress radiographs in skeletally immature patient
          • may indicate gapping through physeal fracture
      • findings
        • usually normal
        • calcification at the medial femoral insertion site (Pellegrini-Stieda Syndrome)
    • MRI
      • modality of choice for MCL injuries
      • identifies location and extent of injury
      • useful for evaluating other injuries
  • Treatment
    • Nonoperative
      • NSAIDs, rest, therapy
        • indications
          • grade I
        • therapy
          • quad sets, SLRs, and hip adduction above the knee to begin immediately
          • cycling and progressive resistance exercises as tolerated
        • return to play
          • grade I may return to play at 5-7 days
      • bracing, NSAIDs, rest, therapy
        • indications
          • grades II
          • grade III
            • if stable to valgus stress in full extension
            • no associated cruciate injury
        • technique
          • immobilizer for comfort
          • hinged knee brace for ambulation
        • return to play
          • grade II return to play at 2-4 weeks
          • grade III return to play at 4-8 weeks
        • outcomes
          • distal MCL injuries have less healing potential than proximal injuries
    • Operative
      • ligament repair vs. reconstruction
        • relative indications
          • acute repair in grade III injuries
            • in the setting of multi-ligament knee injury
            • displaced distal avulsions with "stener-type" lesion
            • entrapment of the torn end in the medial compartment
          • sub-acute repair in grade III injuries
            • continued instability despite nonoperative treatment
              • >10 mm medial sided opening in full extension
          • reconstruction
            • chronic injury
            • loss of adequate tissue for repair
        • technique
          • diagnostic arthroscopy recommended for all surgical candidates to rule out associated injuries
    • Prevention
      • knee bracing
        • functional bracing may reduce MCL injury in football players, particularly interior linemen
  • Techniques
    • MCL repair
      • approach
        • medial approach to the knee
      • indications
        • acute injuries
      • techniques
        • ligament avulsions
          • should be reattached with suture anchors in 30 degrees of flexion
        • interstitial disruption
          • anterior advancement of the MCL to femoral and tibial origins
        • internal brace
    • MCL reconstruction
      • approach
        • medial approach to the knee
      • indications
        • chronic instability
        • insufficient tissue for repair
      • graft type
        • can use semitendinosus autograft or hamstring, tibialis anterior or Achilles tendon allograft
  • Complications
    • Loss of motion
    • Neurological injury
      • saphenous nerve
    • Laxity
      • associated with distal MCL injuries
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