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Collateral Ligament Injuries (MCL & LCL)

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Overview

Exam Detail:

Key Revision Focus: The vast difference in management between MCL (Brace) and LCL (Surgery). Anatomy of the Posterolateral Corner (PLC) association with LCL. Pellegrini-Stieda lesion. Grading of laxity (0-5mm, 5-10mm, >10mm).

1. Clinical Overview

Collateral Ligament Injuries involve the Medial Collateral Ligament (MCL) or Lateral Collateral Ligament (LCL). The MCL is the most commonly injured ligament in the knee. The LCL is rarely injured in isolation and is often part of a catastrophic posterolateral corner (PLC) injury.

Clinical Pearl:

The Rule of Collaterals:

  • MCL: "Mother Nature" heals the MCL. It has a rich blood supply and is extra-articular. Trace It (Brace It).
  • LCL: Nature ignores the LCL. It retracts and fails to heal. Fix It.
  • Exception: A distal MCL avulsion trapped under the pes anserinus (Stener-like lesion) requires surgery.

Key Concepts

  1. MCL Anatomy:
    • Superficial MCL: Primary restraint to Valgus (57-78%). Origin: Medial Epicondyle. Insertion: Tibia (metaphysis).
    • Deep MCL: Meniscofemoral and Meniscotibial ligaments. Check to the meniscus.
  2. LCL Anatomy:
    • Cord-like structure. Origin: Lateral Epicondyle. Insertion: Fibular Head.
    • Primary restraint to Varus.
  3. Mechanism:
    • Valgus Force: Hit from the outside -> MCL tear.
    • Varus Force: Hit from the inside -> LCL tear.
  4. Grading:
    • Grade I: Pain, No laxity (0-5mm).
    • Grade II: Laxity with firm endpoint (5-10mm).
    • Grade III: Laxity with no endpoint (>10mm). Complete rupture.
  5. Pellegrini-Stieda: Calcification at the proximal origin of the MCL seen on X-ray weeks/months after injury. A sign of chronic healing.
  6. Dial Test: Tests for PLC injury. Increased external rotation at 30° but not 90° = Isolated PLC. Increased at 30° AND 90° = PLC + PCL.

Clinical Pearls

  • Testing Position: Collaterals must be tested at 30 degrees flexion.
    • At 0 degrees (full extension), the posterior capsule/ACL/PCL are tight and mask a collateral tear.
    • Laxity at 0 degrees implies a multi-ligament knee injury (Dislocation risk).
  • Peroneal Nerve: Always check foot drop in LCL/Varus injuries (nerve traction).
  • Associated Meniscus: Deep MCL tears often involve the medial meniscus (peripheral tears).

2. Epidemiology

  • MCL: Most common knee ligament injury (40% of all).
    • Skiing (Tip cross), Football, Rugby.
  • LCL: Least common (<2%). Usually high velocity trauma or wrestling.

3. Pathophysiology

Healing Potential

  • MCL:
    • Extra-synovial.
    • Rich blood supply (Genicular arteries).
    • Fibroblasts migrate easily.
    • Heals by scar formation (Grade III tensile strength returns to ~60-70%).
  • LCL:
    • Intra-synovial environment? (Debatable, but floats in fluid often).
    • Retracts upon rupture.
    • Forces on the lateral side (Varus moment during walking) pull the ends apart constantly -> Non-union.

Associated Injuries (The Company They Keep)

  • MCL:
    • ACL: Valgus force often tears ACL first if severe.
    • Medial Meniscus: Attached to deep MCL.
  • LCL:
    • Posterolateral Corner (PLC): Popliteus, Popliteofibular ligament.
    • Cruciates (ACL/PCL).
    • Common Peroneal Nerve.

4. Clinical Presentation

  • Pain: Accurately localized to the medial or lateral epicondyle.
  • Swelling:
    • MCL: Localized medial edema. Often no effusion if capsule intact (fluid leaks out).
    • LCL: Lateral bruising.
  • Instability: "Wobbly" side-to-side movement.

5. Clinical Examination

  1. Look:
    • Ecchymosis.
    • Alignment (Varus/Valgus intent).
  2. Feel:
    • Tenderness: Map the ligament. Origin vs Midsubstance vs Insertion.
    • Pellegrini-Stieda: Hard lump at femoral condyle (chronic).
  3. Stress Testing (The Gold Standard):
    • Valgus Stress Test (MCL):
      • Patient supine. Abduct leg.
      • Apply Valgus force at 0 degrees (tests capsule/cruciates).
      • Apply Valgus force at 30 degrees (isolates superficial MCL).
    • Varus Stress Test (LCL):
      • Apply Varus force at 0 and 30 degrees.
      • Palpate the LCL (Figure of 4 position makes it cord-like).
  4. Neuro:
    • Check EHL/Dorsiflexion (Peroneal nerve).

6. Investigations

X-ray

  • AP/Lateral: usually normal.
  • Pellegrini-Stieda Sign: Calcification at medial femoral condyle (chronic).
  • Segond Fracture: Lateral capsule avulsion (Associated with ACL, not LCL necessarily).
  • Arcuate Sign: Avulsion of fibular head (Pathognomonic for PLC/LCL injury).

MRI

  • Gold Standard for grading.
  • MCL:
    • Grade I: Edema around ligament.
    • Grade II: Partial disruption.
    • Grade III: Complete waviness/discontinuity.
  • LCL:
    • Check for "Biceps Femoris Avulsion" from fibula.

7. Management

Management is dichotomous: MCL = Brace, LCL = Surgery.

ASCII Algorithm:

          COLLATERAL LIGAMENT INJURY
                      ↓
┌─────────────────────┴──────────────────────┐
│                     │                      │
│        MCL          │          LCL         │
│ (Valgus Injury)     │    (Varus Injury)    │
│                     │                      │
└─────────┬───────────┘          ┌───────────┴──────────┐
          ↓                      ↓                      ↓
┌────────────────────┐   ┌───────────────┐      ┌────────────────┐
│      GRADE I-III   │   │  ISOLATED III │      │ MULTI-LIGAMENT │
│   (Isolated)       │   │   (Rare)      │      │ (LCL + ACL/PCL)│
├────────────────────┤   ├───────────────┤      ├────────────────┤
│   CONSERVATIVE     │   │   SURGICAL    │      │    SURGICAL    │
│                    │   │   REPAIR /    │      │ RECONSTRUCTION │
│ 1. Hinged Brace    │   │ RECONSTRUCTION│      │                │
│    (Allow Flex/Ext │   └───────────────┘      └────────────────┘
│     Block Valgus)  │
│ 2. WBAT            │
│ 3. 6 Weeks         │
└────────────────────┘

1. MCL Management

  • Grade I/II: Functional rehab. Crutches for pain 1-2 weeks. No strict bracing needed.
  • Grade III (Complete):
    • Hinged Knee Brace: Worn for 6 weeks.
    • Protocol: Lock in extension for 1 week? Then open 0-90.
    • Weight Bearing: Allowed as tolerated (Weight bearing stimulates healing).
    • Success: >90% return to sport without surgery.
  • Surgical Indications for MCL:
    • Stener-Like Lesion: Distal End of MCL avulses and flips over the Pes Anserinus. Cannot heal.
    • Chronic Instability: Persistent opening causing functional issues.
    • Intra-articular entrapment: End caught in joint.

2. LCL Management

  • Grade I/II: Hinged brace (Extension) for 4-6 weeks.
  • Grade III:
    • Primary Repair: If avulsion (bone) within 2 weeks.
    • Reconstruction: Larson or LaPrade technique using Hamstring autograft/allograft.
    • Reasoning: Chronic varus instability puts massive stress on any ACL graft, leading to ACL failure. You must fix the LCL to protect the ACL.

3. Rehabilitation

  • MCL: Early motion is key to parallelize collagen fibers.
  • LCL: Protect varus. Slower progression.

8. Complications

  • Pellegrini-Stieda Syndrome: Severe pain at medial femoral condyle due to ossification.
    • Tx: Injection, Physio. Excision only if refractory mature bone blocking motion.
  • Stiffness: Common with prolonged immobilization.
  • Instability: Residual laxity is common but usually well tolerated in MCL. Not tolerated in LCL.
  • Peroneal Nerve Palsy: 15-25% in Grade III LCL/PLC injuries.

9. Prognosis & Outcomes

  • MCL: Excellent. RTS at 6-8 weeks for Grade II, 3 months for Grade III.
  • LCL: Variable. Depends on surgical success. Failure rates higher.

10. Evidence & Guidelines

Guidelines

  • AAOS: Strong support for non-operative management of isolated MCL tears.

Landmark Trials

  • Indelicato (1983): Seminal paper. Compared Cast vs Surgery for Grade III MCL.
    • Result: No difference in instability. Surgery group had more stiffness. Established non-op as gold standard. [PMID: 6688360]
  • LaPrade et al: Numerous biomechanical studies defining the anatomy and reconstruction of the PLC/LCL.

11. Patient Explanation

MCL (Inner Side)

Good news. The MCL has a great blood supply and heals like skin—it forms a scab and then a scar. We don't need to sew it. You need a brace to stop the knee wobbling sideways, but you can bend it. It will feel loose for a while but will tighten up.

LCL (Outer Side)

This ligament is more stubborn. It acts like a rubber band that has snapped and shot away. It rarely heals on its own. We usually need to operate to rebuild it, otherwise, your knee will buckle outwards and damage other ligaments.

12. References

  1. Indelicato PA. Non-operative treatment of complete tears of the medial collateral ligament of the knee. J Bone Joint Surg Am. 1983 Dec;65(9):1329-33. [PMID: 6688360] (The Classic).
  2. LaPrade RF, et al. The anatomy of the medial part of the knee. J Bone Joint Surg Am. 2007.
  3. Phisitkul P, et al. MCL injuries of the knee: current concepts review. Iowa Orthop J. 2006.
  4. Shelbourne KD, et al. The natural history of acute, isolated, nonoperatively treated MC injuries. Am J Sports Med. 1999.
  5. Fanelli GC. Surgical treatment of the posterolateral corner of the knee. Sports Med Arthrosc. 2006.
  6. Larson RV. Isometry of the lateral collateral ligament. Am J Sports Med. 1996.
  7. Azar FM. Evaluation and treatment of chronic medial instability of the knee. Sports Med Arthrosc. 2006.
  8. Wijdicks CA, et al. Injuries to the medial collateral ligament and associated medial structures of the knee. J Bone Joint Surg Am. 2010.
  9. Hughston JC. The importance of the posterior oblique ligament in repairs of acute tears of the medial ligaments. J Bone Joint Surg Am. 1994.
  10. LaPrade RF, Engebretsen L, et al. Treatment of acute and chronic combined anterior cruciate ligament and posterolateral knee injuries. Am J Sports Med. 2010.

13. Examination Focus

Common Exam Questions (FRCS/Boards)

  1. At what degree of flexion do you test the MCL? (Answer: 30 degrees to isolate Superficial MCL).
  2. What is the Indelicato study? (Answer: Proved Grade III MCLs heal as well with bracing as with surgery).
  3. What is the Stener-like lesion of the MCL? (Answer: Distal avulsion trapped under pes anserinus / superficial to tibia. Indication for surgery).
  4. What nerve is at risk in LCL repair? (Answer: Common Peroneal Nerve).
  5. Describe Pellegrini-Stieda disease. (Answer: Post-traumatic calcification of the proximal MCL origin).

Viva "Buzzwords"

  • "Superficial vs Deep"
  • "Trace it, Brace it"
  • "Pellegrini-Stieda"
  • "Valgus at 30 degrees"
  • "Indelicato Paper"

Common Pitfalls

  • Testing at extension only: Will miss isolated tears.
  • Missing the PCL/ACL: Laxity at 0 degrees implies cruciate involvement.
  • Bracing LCL tears: They often fail. Refer for opinion.
  • Ignoring Peroneal Nerve symptoms: Must document.

At a Glance

EvidenceStandard
Last UpdatedRecently

Clinical Pearls

  • **The Rule of Collaterals:**

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines