08/01/2026
An anterior cruciate ligament (ACL) tear is a common knee injury involving partial or complete rupture of the ACL, leading to instability of the knee joint, especially during dynamic activities such as running, jumping, and pivoting.
Anatomy and Function of ACL
The ACL is a strong intra-articular ligament of the knee that runs from the anterior intercondylar area of the tibia to the posteromedial aspect of the lateral femoral condyle.
Functions
• Prevents anterior translation of tibia on femur
• Controls rotational stability of the knee
• Maintains knee stability during dynamic and sports activities
Mechanism of Injury
ACL injury most commonly occurs through non-contact mechanisms, although contact injuries may also occur.
Common Mechanisms
• Sudden deceleration while running
• Cutting or pivoting movements
• Landing from a jump with knee in valgus and slight flexion
• Direct blow causing hyperextension or rotation
🔹 A typical history includes a “pop” sound followed by immediate swelling.
Types and Grades of ACL Injury
Based on Severity
• Grade I (Sprain): Mild stretching, ligament intact
• Grade II (Partial tear): Some fibers torn, mild–moderate instability
• Grade III (Complete tear): Full rupture with severe instability
Based on Pattern
• Partial tear
• Complete tear
🔹 Associated injuries: Meniscal tear, MCL injury, cartilage damage (very common)
Clinical Signs and Symptoms
Acute Phase
• Sudden pain
• Rapid swelling due to hemarthrosis (within 1–2 hours)
• Feeling of knee giving way
• Inability to continue activity
Chronic Phase
• Recurrent instability during pivoting
• Weakness and lack of confidence
• Secondary meniscal or cartilage damage if untreated
Physical Examination Tests
Special Tests
• Lachman Test – most sensitive
• Anterior Drawer Test – more useful in chronic cases
• Pivot Shift Test – indicates functional instability
🔹 Findings: Increased anterior tibial translation with soft or absent end-feel
Investigations
• MRI – gold standard for confirming ACL tear and associated injuries
• X-ray – usually normal; helps rule out fractures
• Segond fracture strongly suggests ACL injury
Management of ACL Tear
A. Conservative (Non-surgical)
Indications
• Partial tears
• Low-demand or elderly patients
• No significant instability
Components
• Pain and swelling control
• Restore full ROM
• Quadriceps & hamstring strengthening
• Proprioceptive and neuromuscular training
• Functional knee brace if needed
B. Surgical Management (ACL Reconstruction)
Indications
• Complete tear in young/active patients
• Persistent instability after rehab
• Associated meniscal or ligament injury
Graft Options
• Bone–Patellar Tendon–Bone (BPTB)
• Hamstring tendon
• Quadriceps tendon
🔹 ACL is reconstructed, not repaired
Physiotherapy Rehabilitation
Pre-operative Rehabilitation (Pre-hab)
• Reduce pain and swelling
• Achieve full knee extension
• Improve quadriceps activation
• Maintain cardiovascular fitness
Post-operative Rehabilitation (Phased)
Phase 1: Protection & Early Motion
• Pain and swelling control
• Full extension, gradual flexion
• Quadriceps setting, SLR
Phase 2: Strength & Control
• Closed kinetic chain exercises
• Hamstring and hip strengthening
• Balance and proprioception training
Phase 3: Advanced Strengthening
• Plyometrics
• Agility drills
• Sport-specific training
Phase 4: Return to Sport
• Functional performance testing
• Gradual return to training
• Full return: 6–9 months or longer
Complications
• Knee stiffness
• Graft failure or re-tear
• Persistent instability
• Early onset osteoarthritis
