Approach

The main goal of treatment for an anterior cruciate ligament (ACL) injury is to alleviate symptoms, restore function, and minimise complications.

Initial treatment

Initial treatment consists of protected weight bearing, rest, ice, compression, elevation, and bracing. Non-steroidal anti-inflammatory drugs (NSAIDs) or other analgesics (e.g., paracetamol) may help control pain and swelling, but do not alter the course of the injury. Treatment should be tailored to individual preference, along with the exact nature of the injury. The protected weight bearing, rest, ice, compression, elevation, and medication (PRICEM) acronym defines the initial treatment of all patients.

  • P = Protected weight-bearing exercise with crutches or crutch assisted with a knee immobiliser or similar brace. Avoid prolonged immobiliser use, as severe stiffness and discomfort can develop

  • R = Relative rest

  • I = Ice: useful for initial few days as helps minimise pain and swelling

  • C = Compression

  • E = Elevation

  • M = Medicines (analgesics, NSAIDs as needed).

Arthrocentesis can be considered if there is a large joint effusion. Aspiration may decrease pain and help patients recover early range of motion and knee function.[73] The technique may be utilised if clinically warranted but with appropriate consideration of the risks versus benefits.

Subsequent treatment will depend on whether the patient has low, moderate, or high intensity demands.

  • Low intensity demands: patients who are not regularly active, who are poor fit for surgery, or who do not want to pursue extensive treatment.

    • These patients may be best treated with home physiotherapy exercises, temporary knee bracing, and activity modification to minimise the risk of instability episodes.

  • Moderate intensity demands: patients who partake in sports such as recreational golf, swimming, cycling, and jogging, or other activities in which mild to moderate knee instability may not cause them significant trouble.

    • Depending upon the severity of the injury and the specific lifestyle demands, physiotherapy may work best for this group. A surgical approach may be discussed for patients who are not able to achieve their activity goals or who have frequent knee instability. Surgery should also be considered to lower the risk of future meniscus pathology or procedures, particularly for younger and/or more active patients.[44]

  • High intensity demands: patients with high activity levels and intense physical demands who require dynamic knee stability. These patients include high-level athletes in sports that require frequent cutting, pivoting, jumping, and deceleration (such as soccer, basketball, football, competitive skiing, gymnastics), and people who perform heavy manual labour or who work in a setting where knee instability could prove dangerous (e.g., roofers, construction workers, police, or military personnel).

    • A surgical approach is typically recommended.

Physiotherapy

Gentle (pain-free) active range-of-motion exercises can be instituted within the first few days of injury. Physiotherapy (home or formal) can then proceed with treatment frequency based on the patient's specific situation.

Initial therapy goals include relieving pain and swelling, and re-establishing full range of motion. Subsequent goals include regaining strength, proprioception, and dynamic stability. No methodologically sound evidence has shown superiority of any one particular rehabilitation programme.[74][75]

If the patient experiences recurrent tibiofemoral subluxation episodes or knee instability, this can lead to further attritional injuries including meniscal tears and articular cartilage damage. Activity modification should therefore be encouraged to minimise the risk of instability episodes.[76][77]

There is limited evidence about the benefits of customised bracing for non-operative treatment. However, while patients are regaining strength, an off-the-shelf brace can provide temporary physical support.

Follow-up visits are important to assess progress. If the patient is not able to achieve their activity goals or has repetitive knee instability, surgical consultation may be required to explore surgical treatment options.

Surgery

A surgical approach is usually recommended for patients with high intensity demands. It is also an option for patients with moderate intensity demands who are not able to achieve their activity goals or who have frequent knee instability. There is evidence to suggest that non-surgical management may be an appropriate choice for some patients with moderate to high activity levels, and that physiotherapy should be considered as a primary treatment option in these patients.[78][79] Studies comparing rehabilitation plus either early or delayed ACL reconstruction found no difference in outcomes between these two approaches in young active adults with an acute ACL tear.[78][79][80] However, a conservative approach may not be tolerated by some patients regardless of the severity of injury or activity level, and so the decision should be individualised.

ACL tears are usually treated with reconstruction rather than repair, due to the lower risk of revision surgery compared with repair.[44] Although primary ACL repairs have historically had poor outcomes, repairs with new techniques are emerging and may be warranted for tears that meet certain anatomical features. Continued investigation into the outcomes of these techniques is necessary before indications and contraindications are solidified.

ACL reconstruction is performed primarily to restore the functional stability of the knee, but may also be considered to lower the risk of future meniscus pathology or procedures, particularly for younger and/or more active patients.[44] Although ACL reconstruction is generally performed on people aged 15-45 years, there is evidence of good outcomes following reconstruction among patients aged 40 and over.[81] Reconstruction frequently allows return to high-demand activities, but does not definitively decrease the risk for post-traumatic arthrosis.[82][83]​ 

The surgery can be performed soon after the injury, generally as soon as the swelling has resolved and good range of motion has been restored. Early reconstruction is recommended as the risk of cartilage and meniscal injury begins to increase within 3 months.[44]

Surgeries are usually performed as outpatient procedures under general or spinal anaesthesia, with or without an intra-articular anaesthetic. Risks of the surgery include infection, deep vein thrombosis/venous thromboembolism, neurovascular injury, loss of motion, patellofemoral pain, harvest site pain, patellar fracture, tendon rupture, and pain from hardware.

In general, there is no definitive superiority of one specific ACL reconstruction procedure over another.[84][85][86][87] The choice of graft type should be individualised. Available data and expert opinion suggest that the proficiency and experience of the patient's surgeon should determine which procedure should be done. The American Academy of Orthopaedic Surgeons recommends an autograft, in preference to an allograft, based on improved patient outcomes and decreased ACL graft failure, especially in young and/or active patients.[44] Typical autograft options involve the patellar, hamstring, or quadriceps tendons. Graft choice varies widely based on a number of factors, including patient and surgeon preference.

ACL bony avulsion injuries may be treated with closed, open, or arthroscopic reduction.[88] Revision of ruptured grafts and bilateral ACL injury requires more complex decision making and often involves the use of allografts. Detailed discussion of these issues is outside the scope of this topic.

Postoperative care

Recommendations vary by the exact type and severity of injury, presence or absence of associated injuries, specific surgical technique, rehabilitation protocol, patient's motivation and fitness level, and type and/or intensity of preferred athletic activity.

Physiotherapy begins within the first few days postoperatively. Immobiliser use and specific physiotherapy regimens vary.[89][90][91]​ Functional bracing is generally not recommended following ACL reconstruction. Limited evidence shows that bracing does not benefit a patient’s return to full activity.[44][92] However, the surgeon-patient discussions may consider use of a functional brace during the transitionary phase back to full activity.[92] The potential psychological benefit of a functional brace may support the various ranges of kinesiophobia that could exist when patients transition from physiotherapy to full activity, however, little investigation into this condition exists.

Return to activity

Return to non-contact or low-contact sport (e.g., swimming, cycling) may be faster than return to contact sport (e.g., rugby). Return to full activity in under 3 months after ACL reconstruction has been documented, but generally ranges from 6-12 months.[93] 

Safe return to activity depends upon a dedicated, sequentially phased physiotherapy routine. Regaining full strength, normal biomechanics, and good psychological readiness are critically important for safe return to activity. Appropriate orthopaedic follow-up and physiotherapy assessments are required to ensure that the pace of recuperation is appropriate for the individual patient. A systematic review and evidence statement recommends prehabilitation, followed by 9 to 12 months of post-operative rehabilitation after ACL reconstruction. Progression during rehabilitation, readiness to return to sport and risk for reinjury is measured by strength tests, hop tests, quality of movement and psychological tests.[94]

Psychological monitoring may be particularly relevant for those wishing to return to competitive sport. Results of a systematic review found a relatively low rate of post-operative return to competitive sport following ACL surgery despite a high success rate in terms of knee impairment-based function, thus suggesting that factors other than normalisation of knee function may contribute to return-to-sport outcomes (e.g., psychological factors).[95] Over-zealous return schedules or inadequate physiotherapy can each lead to injury and/or graft failure.[96]

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