Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Anterior Cruciate Ligament Tear (ACL)

SYMPTOMS

The symptoms are pain and immediate haemarthrosis, caused by bleeding from the ruptured ligament. This is an injury common in contact sports such as football, rugby and other high intensity sports such as downhill skiing. There is often a ‘pop’ sound from the knee and an inability to continue.

AETIOLOGY

The typical athlete suffers a hyperextension or valgus rotation sprain. In many cases it is a non-contact injury, where the player loses balance and twists the knee. The ligament can rupture partially or completely. In growing athletes the bone insertion can be avulsed (tibia spine fracture). This injury is often associated with other injuries to cartilage, menisci, capsule or other ligaments.

CLINICAL FINDINGS

There is intra-articular bleeding (haemarthrosis) in most cases. If there is a capsule rupture as well, blood can penetrate from the joint and cause bruising along the lower leg, so the joint effusion does not look too severe. In rare cases, there is no haemarthrosis. The Lachman test is positive if the rupture is complete. This is the most sensitive test and can verify an anterior cruciate ligament rupture in more than 90 per cent of cases. Anterior drawer tests and pivot shift tests are complementary tests for the same purpose. Note! Since there are often associated injuries, the examination must include tests for collateral ligaments, menisci, cartilage and the capsular structures.

INVESTIGATIONS

Clinical examination is the most important tool for diagnosis and should include tests for all ligaments and other structures in the knee. X-ray is valuable to rule out fractures, in particular in growing or elderly athletes. MRI can verify a complete ACL tear in most cases but is more important for evaluating associated injuries.

TREATMENT

An athlete with haemarthrosis and a suspected ACL tear should be seen by an orthopaedic surgeon to consider an early arthroscopy. This procedure can verify the diagnosis and also deal with associated injuries that are often missed. Reconstruction of the ligament is recommended for active athletes in pivoting sports. Sedentary people and participants in non-pivoting sports may recover through rehabilitation only.

REFERRALS

Refer to orthopaedic surgeon for further investigations to verify the extent of the injury. Physiotherapists will be involved in close collaboration with the surgeon.

EXERCISE PRESCRIPTION

Cycling and swimming (not breast stroke) are good alternatives to keep up general fitness. Rehabilitation back to full sport usually takes around six months with or without surgery.

EVALUATION OF TREATMENT OUTCOMES

Monitor clinical symptoms and signs. Different functional knee scores for different sports are available
to measure when the knee allows the return to full sport.

DIFFERENTIAL DIAGNOSES

Posterior cruciate ligament rupture. Initial posterior sagging will give a sense of anterior translation of the tibia during a Lachman or anterior drawer test and mislead the examiner but the posterior drawer test is positive. Associated injuries, such as a bucket handle meniscal tear, can cause the knee to lock, and mask a positive Lachman test.

PROGNOSIS

Surgery (ACL reconstruction) will allow return to professional sports in around six to nine months. The risk of re-rupture is about 5 per cent within five years. The reconstruction will protect the knee from further meniscus or cartilage injuries. However, reconstruction or not, the knee will be more vulnerable to stress and in the long term, 10 to 20 years, the risk of developing osteoarthritis is significant, compared to a non-injured knee.

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