Management of combined injuries of the ACL and medial knee

Background: Combined injuries of the anterior cruciate ligament (ACL) and medial knee structures occur in 20% to 40% of ACL ruptures, typically resulting from valgus stress or excessive rotation. Despite their prevalence, management remains controversial due to a lack of consensus in the literature and the risk of chronic instability or early osteoarthritis.

Objective: This article reviews the anatomy, biomechanics, and diagnostic strategies for medial knee injuries and presents treatment algorithms and clinical outcomes based on the 2023 Société Française d’Arthroscopie (SFA) symposium.

Key Points: Medial stability is maintained by three layers, including the superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL), and posterior oblique ligament (POL). Diagnosis relies on comparative clinical exams, including valgus stress and the anteromedial rotatory instability test, supplemented by stress radiography and MRI. Grade 1 injuries require no medial intervention. Grade 2 injuries may be managed non-operatively unless distal entrapment or elite athletic status necessitates repair. Grade 3 injuries, characterized by laxity in extension, require surgical reconstruction. Technical requirements include precise anatomical tunnel placement for sMCL, dMCL, and POL grafts. Data from 722 patients indicate that while ACL+MCL injuries have higher rates of stiffness and repeat surgery for cyclops lesions, early mobilization and weight-bearing without rigid bracing optimize functional recovery.

Conclusion: Effective management of combined ACL and medial knee injuries requires a grade-based approach. Early anatomical reconstruction and immediate mobilization are essential to restore kinematics and minimize the risk of postoperative joint stiffness.