Pathophysiology

The anterior cruciate ligament (ACL) provides stability to the knee joint by preventing the tibia from sliding on the femur and provides rotational stability in twisting movements. ACL injury often occurs during sports when the foot is planted and a sudden force hits the knee whilst the leg is straight or slightly bent. This can happen with sudden changes of direction, slowing down when running or landing from a jump. It is common in football, skiing and rugby.

Symptoms

• Hearing a ‘pop’ or ‘crack’ or feeling of the knee giving way at the time of injury
• Sudden onset of pain and development of bruising and swelling within a few hours of injury
• Difficulty standing on the knee initially
• Being unable to straighten the knee initially

Management

• Activity modification
• Ice or heat
• Pain relief
• Physiotherapy including range of movement exercises and a graded strengthening programme
• Orthopaedic options- If traumatic and active/sporting lifestyle may consider repair, otherwise 3-6 months conservative management

Investigations

MRI with trauma if considering surgery