What is an Anterior Cruciate Ligament (ACL) injury, how is it diagnosed, treated, and what is the prognosis and potential complications?

From the Guidelines

An Anterior Cruciate Ligament (ACL) injury is a serious condition that requires prompt diagnosis and treatment to prevent long-term morbidity and mortality, and to improve quality of life. The diagnosis of an ACL injury typically begins with a physical examination where the doctor checks for swelling, tenderness, and knee stability using tests like the Lachman test or anterior drawer test. Imaging studies such as MRI scans confirm the diagnosis by clearly showing the torn ligament, as MRI has many distinct advantages for the evaluation of the injured knee in the setting of negative radiographs 1. Treatment options depend on the severity of the injury and the patient's activity level. For partial tears in less active individuals, non-surgical treatment including rest, ice, compression, elevation (RICE protocol), physical therapy, and bracing may be sufficient. However, complete tears, especially in athletes or active individuals, often require surgical reconstruction using tissue grafts (autografts from the patient's hamstring or patellar tendon, or allografts from donors), with autograft considered over allograft to improve patient outcomes and decrease ACL graft failure rate, particularly in young and/or active patients 1. Post-surgery rehabilitation is crucial and typically lasts 6-12 months, focusing on restoring range of motion, strength, and stability, with a combination of strength and motor control training, and progression criteria based on objective physical and psychological criteria 1. The prognosis is generally good with proper treatment, with most patients returning to normal activities within 6-9 months after surgery. Potential complications include chronic knee instability if left untreated, increased risk of osteoarthritis later in life, risk of re-injury, and surgical complications such as infection, blood clots, or graft failure, with cartilage injury at ACLR and medial meniscectomy being significant risk factors for knee osteoarthritis 1. Preventive measures like proper training techniques and strengthening exercises can reduce the risk of initial injury or re-injury.

Some key points to consider in the treatment and rehabilitation of ACL injuries include:

• The use of MRI scans to confirm the diagnosis and evaluate the extent of the injury 1
• The importance of early rehabilitation and progression criteria based on objective physical and psychological criteria 1
• The need for a combination of strength and motor control training in the rehabilitation protocol 1
• The potential benefits of autograft over allograft in surgical reconstruction 1
• The significant risk factors for knee osteoarthritis, including cartilage injury at ACLR and medial meniscectomy 1

Overall, the management of ACL injuries requires a comprehensive approach that takes into account the severity of the injury, the patient's activity level, and the potential risks and complications associated with treatment. The goal of treatment should always be to improve the patient's quality of life and reduce the risk of long-term morbidity and mortality.

From the Research

Definition and Diagnosis of ACL Injury

• An Anterior Cruciate Ligament (ACL) injury is a common knee injury that can have negative long-term physical and psychological impacts, especially in young and active individuals 2.
• The diagnosis of an ACL injury is made with a combination of patient's history, clinical examination, and imaging studies such as magnetic resonance imaging (MRI) 2, 3.
• The classic presentation of an ACL injury is a non-contact twisting injury with an audible pop and the rapid onset of swelling 3.
• Physical examination tests such as the Lachman test, anterior drawer test, and pivot shift test can be used to evaluate ACL injury, with the Lachman test being the most accurate test for detecting an ACL tear 4, 5.

Treatment of ACL Injury

• The treatment options for ACL injury include rehabilitation as first-line treatment, ACL reconstruction (ACLR) and post-operative rehabilitation, and pre-operative rehabilitation followed by ACLR and post-operative rehabilitation 2.
• Operative treatment is often recommended for active patients, while less-active patients may not require surgery 3.
• The goal of treatment is to restore knee function, address psychological barriers to activity participation, prevent further injury and osteoarthritis, and optimize long-term quality of life 2.

Prognosis and Complications of ACL Injury

• The long-term sequelae of ACL injury include knee osteoarthritis in up to 90 percent of patients 4.
• Patients who undergo surgery must commit to appropriate rehabilitation for the best outcome 4.
• The prognosis of ACL injury is generally good with proper treatment and rehabilitation, but the risk of complications such as knee osteoarthritis and further injury remains 2, 4.
• Primary prevention of ACL injury includes specific proprioceptive and neuromuscular training exercises to improve knee stability 4.

Rehabilitation After ACL Injury

• Rehabilitation after ACL injury is critical for successful recovery, and physical therapy plays a key role in the rehabilitation process 6.
• Rehabilitation protocols vary greatly, but there is a trend towards more accelerated, individualized protocols that vary in length and modalities based on patient-specific findings and preferences 6.
• New protocols emphasize early weight bearing, open kinetic chain (OKC) exercises, and other alternative modalities such as neuromuscular electrical stimulation and blood flow restriction 6.