Etiology — what causes it

MCL injury — valgus force, often from contact on the lateral knee or a planted-foot pivot. LCL injury — varus force, less common, often associated with higher-grade multi-ligament injuries.

Epidemiology — who gets it

MCL is the most commonly injured knee ligament in contact sports (football, hockey, rugby). LCL isolated injury is rare.

Clinical signs

MCL — valgus stress at 30° flexion reproduces medial pain (Grade I) or laxity (Grade II–III); valgus laxity in full extension suggests higher-grade multi-ligament injury. LCL — varus stress at 30° flexion; in extension suggests PCL or posterolateral corner injury.

Symptoms

Medial (MCL) or lateral (LCL) knee pain with tenderness over the ligament, often with mild effusion. Higher-grade injuries may include instability, especially with cutting.

Best evidence for chiropractic treatment

Grade I — return to sport in 1–3 weeks with graded loading. Grade II — 3–6 weeks; bracing useful, especially for higher-demand returns. Grade III isolated MCL — usually conservatively managed with bracing (Reider et al., AJSM); ACL-MCL combined often surgical for the ACL. LCL Grade III often requires surgical consideration.

Subtypes

  • Grade I. Microscopic tearing, no laxity.
  • Grade II. Partial tear, mild-to-moderate laxity with firm endpoint.
  • Grade III. Complete tear, marked laxity, no endpoint.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Most MCL injuries heal well with graded loading and bracing as needed. LCL and multi-ligament involvement requires more careful assessment.