MEDIAL COLLATERAL LIGAMENT INJURIES
Valgus Stress | Grade I-III | Usually Conservative | Combined ACL
MCL GRADING (Valgus Stress)
Critical Must-Knows
- sMCL is PRIMARY restraint to valgus at 30 degrees
- Most MCL injuries heal conservatively (90%+)
- Combined MCL/ACL: treat ACL, MCL heals with rehab
- Surgery indicated: chronic instability, Grade III with ACL, multiligament
- Test at 30 degrees flexion to isolate MCL
Examiner's Pearls
- "Test at 0 degrees: posteromedial corner involvement if unstable
- "Stener lesion equivalent: sMCL displaces over pes anserinus
- "sMCL originates 5cm proximal to joint line
- "dMCL is part of posteromedial capsule
Clinical Imaging
Imaging Gallery
Critical Exam Concepts
Conservative First
90%+ of MCL injuries heal without surgery. Even Grade III isolated MCL usually heals. Functional bracing and early ROM is key.
Test at 30 Degrees
Valgus stress at 30 degrees isolates the MCL. At 0 degrees, posteromedial corner and cruciates also contribute. Compare sides.
Combined MCL/ACL
Address ACL surgically, MCL usually heals. Exception: Grade III MCL with valgus laxity at 0 degrees may need MCL surgery at same time.
Surgical Indications
Surgery for: chronic instability, failed conservative, multiligament injury, Stener equivalent with MCL trapped.
MCL Injury Treatment Guide
| Grade | Laxity | Endpoint | Treatment |
|---|---|---|---|
| Grade I | None | Firm | Functional brace, early ROM |
| Grade II | 1-5mm increased | Present | Hinged brace 4-6 weeks, rehab |
| Grade III Isolated | 5-10mm increased | Absent | Hinged brace 6-8 weeks, usually heals |
| Grade III + ACL | Significant | Absent | ACL reconstruction, MCL usually heals (may need repair) |
VALMCL Injury Mechanism
Memory Hook:VAL-gus stress causes MCL injury!
TWOMCL Examination
Memory Hook:Test at TWO positions - 30 and 0 degrees!
SDPLayers of Medial Knee
Memory Hook:SDP - Warren layers of the medial knee!
Overview and Epidemiology
MCL Healing Capacity
MCL has excellent healing capacity due to extraarticular location and good blood supply. Even Grade III tears usually heal with bracing and rehabilitation. This differentiates it from ACL/PCL.
Epidemiology
- Most common knee ligament injury
- Contact sports: football, rugby, hockey
- Skiing (combined ACL/MCL common)
- Males greater than females
- Often combined injuries
Mechanism
- Valgus stress: Most common
- Contact: Blow to lateral knee
- Non-contact: Cutting, pivoting
- External rotation: May also injure
- Combined ACL: Common mechanism
Pathophysiology and Mechanisms
MCL Complex Anatomy
Superficial MCL (sMCL):
- Primary valgus restraint
- Origin: Medial femoral epicondyle (5cm proximal to joint)
- Insertion: Proximal medial tibia (5-7cm distal to joint)
- Two attachment sites: proximal soft tissue, distal firmly on tibia
Deep MCL (dMCL):
- Part of posteromedial capsule
- Meniscofemoral and meniscotibial ligaments
- Attaches to medial meniscus
These are the key anatomical facts for the exam.
Valgus at 0 Degrees = More Severe
Valgus laxity at 0 degrees extension indicates injury to posteromedial corner and possibly cruciates in addition to MCL. This is a more severe injury pattern requiring careful evaluation.
Classification Systems
MCL Injury Grading
| Grade | Pathology | Examination | Laxity |
|---|---|---|---|
| I | Fiber stretch, intact | Tender, firm endpoint | 0-5mm, no increase |
| II | Partial tear | Lax with endpoint | 5-10mm increased |
| III | Complete rupture | Lax without endpoint | Greater than 10mm increased |
Compare to contralateral side - absolute values vary between individuals.
Clinical Assessment
History
- Mechanism: Valgus blow, contact
- Pain: Medial knee, at time of injury
- Swelling: Often localized medial
- Instability: Giving way with valgus
- Associated injuries: Pop (ACL), locking (meniscus)
Examination
- Tenderness: Along MCL course
- Valgus stress 30 degrees: Isolates MCL
- Valgus stress 0 degrees: PMC involved if lax
- ACL tests: Lachman, pivot shift
- Meniscus: McMurray, joint line
Valgus Stress Test Technique
Patient supine. At 30 degrees flexion, stabilize thigh, apply valgus force to ankle. Compare opening and endpoint to contralateral side. Repeat at 0 degrees - laxity here indicates posteromedial corner injury.
Key Clinical Pearls
Palpate the MCL: Tenderness along course helps identify injury location - femoral, mid-substance, or tibial.
Check ACL: Always perform Lachman and pivot shift. Combined injuries are common.
Investigations
MRI Assessment
Sensitivity: Excellent for MCL injuries.
Findings: Edema surrounding MCL, discontinuity, thickening.
Tear location: Femoral, mid-substance, tibial.
Associated injuries: ACL, meniscus, cartilage, bone bruise.
MRI not always required for isolated MCL but helps define Grade III and associated injuries.
Pellegrini-Stieda Lesion
Pellegrini-Stieda lesion = calcification at MCL femoral origin. Represents chronic MCL injury with calcification of hematoma. Visible on X-ray. May be asymptomatic.
Management Algorithm
MCL Injury Management
Treatment Pathway
RICE, brace in extension. Examine for associated injuries. Consider MRI if Grade III or associated injury suspected.
Hinged brace allowing ROM. Early physiotherapy. Weight bearing as tolerated. Return to sport 2-6 weeks.
Hinged brace 6-8 weeks. Protected weight bearing initially. Supervised rehabilitation. Most heal.
ACL reconstruction if indicated. MCL usually heals during ACL recovery. Surgery if Grade III with laxity at 0 degrees.
Surgical Technique
MCL Repair Techniques
Acute femoral avulsion: Suture anchors or bone tunnels to restore origin.
Acute tibial avulsion: Screw with soft tissue washer.
Mid-substance tear: Primary repair with non-absorbable sutures if acute.
Augmentation with graft may be added for severe injuries.
Avoid Overtensioning MCL
When repairing or reconstructing MCL, avoid overtensioning which leads to loss of flexion and lateral compartment overload. Tension at 20-30 degrees flexion with slight valgus.
Complications
| Complication | Cause | Prevention | Management |
|---|---|---|---|
| Stiffness | Prolonged immobilization | Early ROM | Physiotherapy, MUA if severe |
| Chronic laxity | Inadequate healing | Appropriate bracing duration | Late reconstruction |
| Calcification | Hematoma | Early ROM, avoid NSAIDs acutely | Usually asymptomatic |
| Saphenous nerve | Surgery | Careful dissection | Neuroma management |
Stiffness Prevention
Early ROM is key to preventing stiffness. Even Grade III injuries benefit from hinged bracing allowing motion rather than cast immobilization. Stiffness is the enemy.
Postoperative Care
Rehabilitation Protocol
Hinged brace locked initially. Toe touch weight bearing. Quad sets, SLR.
Progressive ROM in brace. Increase weight bearing. Gentle strengthening.
Full ROM. Progressive resistance. Proprioception. Wean brace.
Sport-specific training. Functional testing. Full return when stable.
Conservative vs Surgical Rehab
Conservative: Faster progression, early ROM encouraged. Surgical (reconstruction): More protected initially, similar final timeline. Both aim for full ROM and strength before return to sport.
Outcomes and Prognosis
Outcomes by Grade
Grade I: Excellent outcomes. Return to sport 1-2 weeks. Minimal long-term sequelae.
Grade II: Good outcomes. Return to sport 4-6 weeks. Bracing during sport initially helpful.
Grade III Isolated: Most heal with bracing. Some chronic laxity may persist but often asymptomatic.
Combined Injuries: Outcomes depend on addressing all pathology. ACL reconstruction with MCL healing typical.
Evidence Base and Key Studies
Non-Operative Treatment of MCL
- Classic study of conservative MCL treatment
- Functional bracing with early ROM
- Excellent outcomes for isolated injuries
- Established conservative approach
Combined ACL/MCL Injury Management
- RCT: ACL reconstruction + MCL surgery vs ACL alone
- No difference in outcomes
- MCL heals with ACL reconstruction
- Avoid MCL surgery in most combined
MCL Reconstruction Outcomes
- MCL reconstruction for chronic instability
- 85% good/excellent outcomes
- Restored valgus stability
- Low complication rate
Grade III MCL Natural History
- Isolated Grade III MCL treated conservatively
- High rate of healing
- Some residual laxity but not symptomatic
- Good functional outcomes
MCL Healing Biology
- MCL has extraarticular location
- Good blood supply
- Scar formation leads to healing
- Differs from intraarticular ACL
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Contact Sports Injury
"A 22-year-old rugby player sustains a valgus blow to his knee during a tackle. He has medial knee pain and swelling. Examination shows Grade II laxity at 30 degrees with a firm endpoint. Lachman is negative. How would you manage this?"
Scenario 2: Combined ACL/MCL Injury
"A 28-year-old skier with a twisting fall presents with a swollen knee. Examination shows Grade III MCL laxity and positive Lachman with pivot shift. MRI confirms ACL rupture and Grade III MCL tear. What is your treatment plan?"
Scenario 3: Chronic MCL Instability
"A 35-year-old presents with ongoing medial knee instability 6 months after an MCL injury that was treated conservatively. He has failed prolonged rehabilitation. Valgus stress shows Grade II laxity at 30 degrees. What would you recommend?"
MCQ Practice Points
Primary MCL Function
Q: What is the primary function of the sMCL? A: Restraint to valgus stress - provides 78% of valgus restraint at 25 degrees flexion.
Why Test at 30 Degrees
Q: Why test MCL at 30 degrees flexion? A: Isolates the MCL. At 0 degrees, posteromedial capsule and cruciates also contribute. Laxity at 0 degrees indicates more severe injury.
MCL Healing
Q: Why does MCL heal better than ACL? A: Extraarticular location and good blood supply. Not bathed in synovial fluid. Forms healing scar tissue.
Combined ACL/MCL
Q: How should combined ACL/MCL injury be treated? A: ACL reconstruction, MCL heals conservatively. Exception is Grade III MCL with laxity at 0 degrees may need surgical MCL.
Pellegrini-Stieda
Q: What is Pellegrini-Stieda lesion? A: Calcification at MCL femoral origin from chronic injury with hematoma calcification. Visible on X-ray.
Stener Equivalent
Q: What is the MCL Stener equivalent? A: sMCL displaces over pes anserinus preventing healing. Indication for surgical reduction.
Australian Context
Clinical Practice
- Common contact sports injury
- Conservative treatment standard
- Functional bracing widely used
- Combined ACL/MCL protocol established
- Reconstruction rarely needed
Funding and Access
- Braces available/subsidized
- Physiotherapy accessible
- Return to sport protocols clear
- Sports medicine specialists manage
Orthopaedic Exam Relevance
MCL injuries are common viva topics. Know the conservative treatment algorithm, when NOT to operate, and how to manage combined injuries. Also know the anatomy and grading system.
MEDIAL COLLATERAL LIGAMENT INJURIES
High-Yield Exam Summary
Grading (Valgus at 30 degrees)
- •Grade I: Tender, firm endpoint, no laxity
- •Grade II: Laxity with endpoint
- •Grade III: Laxity without endpoint
- •Compare to contralateral side
Examination Key Points
- •Test at 30 degrees: Isolates MCL
- •Test at 0 degrees: PMC if unstable here
- •Always check ACL (Lachman, pivot)
- •Palpate along MCL course
Treatment Algorithm
- •Grade I-II: Conservative (90%+ heal)
- •Grade III isolated: Usually conservative
- •Combined ACL/MCL: ACL surgery, MCL heals
- •Surgery: chronic instability, Stener, multilig
Anatomy Pearls
- •sMCL: primary valgus restraint
- •Origin 5cm proximal to joint line
- •dMCL: part of posteromedial capsule
- •Warren layers: 3 layers medial knee
Return to Sport
- •Grade I: 1-2 weeks
- •Grade II: 4-6 weeks
- •Grade III: 8-12 weeks
- •Protective brace may help initially