What is the best course of treatment for a suspected anterior cruciate ligament (ACL) tear with persistent pain below the knee?

Management of Suspected ACL Tear with Persistent Pain

For a young, active patient with a suspected ACL tear who wants to prevent long-term problems and return to exercise, ACL reconstruction should be performed within 3 months of injury to minimize risk of additional meniscal and cartilage damage, followed by 9-12 months of structured rehabilitation. 1

Immediate Diagnostic Steps

Confirm the diagnosis first - you need proper imaging before making treatment decisions:

• MRI is the gold standard with 96% sensitivity and 97% specificity for ACL tears 1
• If you have a painful, tense knee effusion causing significant discomfort, aspiration can provide symptom relief 2, 1
• The Lachman test is the most accurate physical exam maneuver (>80% sensitive) if you haven't had formal imaging yet 3

Treatment Decision Algorithm

Your age, activity level, and goals determine the pathway:

For Active Patients Who Want to Return to Exercise (Your Situation):

ACL reconstruction is recommended because: 2, 1

• It lowers the risk of future meniscus pathology and procedures 2
• It may improve long-term pain and function 2
• Younger, more active patients benefit most from surgical stabilization 1
• Timing matters critically: reconstruction within 3 months reduces risk of additional cartilage and meniscal injury 1

If You Were Sedentary or Low-Activity:

• Supervised rehabilitation with activity modification would be appropriate 2
• Delayed reconstruction only if functional instability develops 4

Pre-Surgical Preparation (Prehabilitation)

Before surgery, you need at least one visit with a physical therapist to optimize outcomes: 2, 5

• Measure and restore full knee extension - preoperative extension deficit is a major risk factor for postoperative extension problems 2
• Measure quadriceps strength - deficits >20% negatively impact outcomes at 2 years 2
• Prehabilitation ensures better self-reported knee function up to 2 years after reconstruction 2

Surgical Approach

ACL reconstruction (not repair) is the standard because repair has higher revision rates: 2, 1

Graft Selection:

Choose based on your priorities: 1

• Bone-patellar tendon-bone (BTB) autograft: Lower risk of graft failure or infection, but higher risk of anterior knee pain and kneeling pain 1
• Hamstring tendon autograft: Lower risk of anterior knee pain, but slightly higher graft failure risk 1

Both single-bundle and double-bundle techniques have similar outcomes 1

Post-Operative Rehabilitation Protocol

Rehabilitation should continue for 9-12 months based on functional criteria, not just time: 2, 5

Early Phase (Weeks 1-4):

• Immediate weight bearing is allowed if you have correct gait pattern, no pain, no effusion, and no temperature increase 2
• Use crutches initially if needed to maintain proper gait 2
• Start isometric quadriceps exercises in week 1 when they provoke no pain 2
• Cryotherapy can reduce pain in the first postoperative week 2
• Electrostimulation combined with conventional rehabilitation may improve muscle strength for up to 2 months 2

Intermediate Phase (Weeks 2-12):

• Closed kinetic chain (CKC) exercises from week 2 2
• Open kinetic chain (OKC) exercises from week 4 in restricted range of motion (90-45°) 2
• Replace isometric exercises with concentric and eccentric exercises when the knee doesn't react with effusion or increased pain 2
• Do not return to running before 12 weeks minimum to allow adequate graft remodeling 5

Advanced Phase (3-12 months):

• Combine strength training with motor control exercises 1
• Use functional evaluation including hop tests as one factor to determine return to sport 2, 1
• Continue rehabilitation for the full 9-12 months depending on your specific return-to-activity goals 2, 5

Critical Pitfalls to Avoid

Delaying surgery beyond 3 months increases your risk of additional meniscal and cartilage damage that could have been prevented: 1

Don't rush return to activity - even though you're eager to exercise, premature return increases re-injury risk. The rehabilitation timeline exists for biological reasons related to graft remodeling. 5

Address any preoperative extension deficit or quadriceps weakness before surgery - these are major risk factors for poor outcomes that can be modified with prehabilitation. 2, 5

Long-Term Considerations

Even with successful reconstruction, you face increased osteoarthritis risk long-term: 1

• Up to 90% of ACL injury patients develop some degree of knee osteoarthritis 3
• Address modifiable risk factors: maintain healthy weight and continue quadriceps strengthening exercises indefinitely 1
• Consider neuromuscular training programs to reduce risk of contralateral ACL injury 2, 1

Comparison: Early Surgery vs. Delayed Optional Surgery

Recent high-quality evidence shows no difference in patient-reported outcomes at 11 years between early reconstruction and initial rehabilitation with optional delayed reconstruction (52% eventually had surgery in the delayed group). 6 However, this study included all activity levels. For your specific situation - wanting to return to exercise and prevent long-term problems - early reconstruction within 3 months remains the guideline-recommended approach to protect menisci and cartilage from progressive damage. 1