Definition: Stretch or tear of the medial collateral ligament (MCL).
- Ligamentous injuries have been cited to account for ~40% of knee injuries (Bolen 2000)
- The MCL is the most commonly injured ligament, accounting for ~8% of all knee injuries (Majewski 2006)
- Women > Men (Swenson 2013)
- Direct blows are the most common mechanism and typically cause more severe injuries (Singhal 2010).
- Indirect mechanisms are less common. They occur with a valgus stress with external rotation force to the lateral knee, i.e. when an athlete’s shoe gets caught on a playing surface during quick direction changes, or when an athlete catches a tip or the inside edge of a ski or skate.
- The MCL is the first (and therefore most common) structure affected in a predictable series of injuries from a valgus stress
- General Principles
- Should be performed as soon as possible as swelling and muscle spasm occur early and obscure assessment
- Both knees should be examined using a systematic approach – inspection, palpation, testing range of motion, and using special maneuvers specific for certain injury patterns
- While it is important to evaluate the entire knee, this section will focus on findings specific to MCL injuries
- Assess the patient’s gait and ability to bear weight which can sometimes indicate injury severity
- Patients can often have localized swelling but effusions are uncommon in isolated MCL injuries.
- The presence of an effusion is highly suggestive of associated fractures, meniscal or cruciate injuries.
- Tenderness at the medial joint line suggests MCL injury
- Can also indicate medial meniscal injury and is therefore a nonspecific finding
- Range of Motion
- Pain from an isolated MCL injury can limit active motion, particularly terminal knee extension and flexion beyond 100 degrees
- Isolated MCL injury generally does not constrain passive range of motion
- Special Maneuvers – Valgus stress (abduction) test
- Laxity at 30 degree flexion => MCL injury
- Laxity at full extension => MCL +/- ACL/PCL injuries.
- To objectively assess laxity, hold finger at medial joint line and feel for medial joint widening (see injury grading below).
- Ultrasound can help quantify degree of medial joint widening.
- Always compare to uninjured knee to understand baseline joint laxity
- Detection of ligamentous laxity can be limited by spasm of surrounding muscles
- Grade I (mild)
- Stretch injury
- No laxity elicited with valgus stress (i.e. <5mm medial joint widening)
- Grade II (moderate)
- Partial tear of MCL
- 5-9mm medial joint widening
- Grade III (severe)
- Complete tear
- 10mm or more of medial joint widening
- Typically less painful versus lower grade injuries
- Regardless of injury grade, ED management of isolated MCL injuries is supportive
- Ice, compression, elevation, and NSAIDs
- Weight bearing as tolerated
- A hinged knee brace should be applied
- Protect against additional valgus injury
- Avoid knee immobilizers as they can lead to knee stiffness and muscle weakness
- Always encourage early mobilization (within the first week)
- Indications for emergent ortho consultation
- Associated open fracture
- Neurovascular deficit
- Suspected tibiofemoral dislocation
- Unstable knee joint
- Due to muscle spasm and soft tissue swelling, an unstable knee might appear stable
- Immobilize, make non-weight bearing, and obtain close follow-up if unstable joint without evidence of dislocation (within 1 week) for re-examination
Imaging in the ED
- Plain Radiographs
- Views: AP, lateral, patellar (45 degrees flexion)
- Generally not necessary to evaluate isolated MCL injuries, but should be performed if concern for associated fractures
- Typically normal in isolated MCL injuries
- A “reverse segond” fracture is a subtle avulsion fracture of the medial tibial condyle that represents an avulsion of the deep portion of the MCL
- Ultrasound (Craft 2015)
- Can identify MCL injuries via abnormal MCL appearance
- Can quantify degree of medial joint opening during valgus stress testing
- CTA: Should be performed in all patients with clinical features concerning for an unstable knee, who do not have hard signs of vascular injury
- MRI: Can be done at outpatient for simple MCL injury to help identify extent of injury.
- Functional recovery from isolated MCL injuries is dependent on grade of injury, and achieved with physical therapy focused on gradual strengthening and range of motion exercises
- Grade I: return to activity in ~1wk
- Grade II: 2-4wks
- Grade III: 4-8wks
- Multiple prospective case-control studies have shown no difference in functional outcomes for non-op vs operative management in isolated MCL injuries (Reider 1994, Lundberg 1996, Lundberg 1997).
Take Home Points
- MCL injuries are commonly seen in the ED and the diagnosis is based on the physical exam
- Isolated MCL injuries can be managed conservatively in the ED, and safely discharged with sports medicine follow-up in 1-2 weeks
- If the patient has an unstable knee or an effusion, consider a tibiofemoral dislocation
Core EM: True Knee and Patellar Dislocations
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