What treatment is recommended for a patient experiencing a torn anterior cruciate ligament (ACL) with knee instability and pain?

Management of ACL Tear with Knee Instability and Pain

For a patient with ACL tear causing knee instability and pain, ACL reconstruction should be performed as soon as possible—ideally within 3 months of injury—particularly in younger and more active patients, to prevent additional meniscal and cartilage damage and improve long-term pain and function. 1

Immediate Management

Acute Symptom Relief

• Consider aspirating painful, tense knee effusions to provide immediate symptom relief in the acute setting 1

Surgical Timing is Critical

• Early reconstruction within 3 months is strongly recommended because the risk of additional cartilage and meniscal injury starts to increase within this timeframe 1, 2
• Delaying beyond 3 months significantly increases risk of secondary injuries that worsen long-term outcomes 2
• This represents a shift from previous guidelines that allowed up to 5 months 1

Surgical Approach: ACL Reconstruction

Why Reconstruction Over Repair

• ACL reconstruction should be performed rather than repair due to lower risk of revision surgery 1

Graft Selection Algorithm

For skeletally mature patients, choose between two autograft options based on patient priorities: 1, 2

Option 1: Bone-Patellar Tendon-Bone (BTB) Autograft

• Favor BTB when minimizing graft failure risk is the priority, especially in young, high-demand athletes 1, 2
• Reduces risk of graft failure compared to other options 1, 2
• Reduces infection risk 1, 2
• Trade-off: Higher risk of anterior/kneeling pain 1, 2

Option 2: Hamstring Autograft

• Favor hamstring when avoiding anterior knee pain is the priority 1, 2
• Lower donor site morbidity 2
• Reduces anterior and kneeling pain compared to BTB 1, 2
• Consider adding lateral extra-articular augmentation (ALL reconstruction or LET) with hamstring grafts in select patients to reduce graft failure and improve short-term function 1, 2

Autograft Strongly Preferred Over Allograft

• Use autograft over allograft to improve outcomes and decrease graft failure rate, particularly in young and/or active patients 1
• This represents updated strong evidence from the 2023 AAOS guidelines 1

Surgical Technique Options

• Both single-bundle and double-bundle reconstruction techniques produce similar outcomes, allowing surgeon preference to guide selection 1, 2

Special Consideration: Combined ACL/MCL Tears

If the patient has a combined ACL and MCL tear: 1, 3

• Treat the MCL non-surgically while proceeding with ACL reconstruction, as non-surgical MCL treatment results in good outcomes 1
• MCL surgical treatment may be considered only in select cases 1
• Complete preoperative physical therapy to restore knee range of motion and allow attempted MCL healing before ACL reconstruction 3

What NOT to Do

Avoid Functional Bracing

• Do not use functional knee braces routinely after isolated primary ACL reconstruction as they provide no clinical benefit 1, 2

Avoid Prophylactic Bracing

• Prophylactic bracing is not recommended to prevent ACL injury 1

Return to Sport Considerations

• Use functional evaluation (such as hop testing) as one factor to determine return to sport clearance 1, 2
• Apply criterion-based rather than purely time-based progression 2

Key Clinical Pitfalls to Avoid

• Do not delay reconstruction beyond 3 months in young, active patients as this substantially increases risk of secondary meniscal and cartilage injury 2
• Do not assume all ACL tears require immediate surgery—patient age, activity level, and functional demands should guide the decision, though younger/more active patients benefit most from reconstruction 1
• Do not perform ACL repair instead of reconstruction when surgery is indicated, as repair has higher revision rates 1