The anterior cruciate ligament (ACL) makes up one of the 4 main ligaments of the knee. In fact, it is the most important and commonly injured ligament, accounting for almost half of knee injuries worldwide. There are almost 400,000 ACL reconstruction in USA. Well known sportsman with anterior cruciate ligament injuries include Zlatan Ibrahimovic of Manchester United, Tom Brady of the New England Patriots (National Football League) and Alex Morgan of the U.S.A World Cup Winning Women’s team.
The role of anterior cruciate ligament is to provide stability to the knee joint. The ACL is critical in maintaining knee stability during pivoting motion, twisting and turning of the knee. ACL injury is higher in people who participate in soccer, badminton, skiing and basketball.
Common mechanisms of ACL injury include:
Non contact (70%):
- pivoting during acceleration or deceleration
- forceful twisting of the knee with the foot immobilised
- ACL is usually torn in severe valgus stress e.g. opponent crushing into the patient’s knee from the outside to inside
The anterior cruciate ligament is usually torn by a significant knee injury that is associated with knee pain and swelling. The swelling of the involved knee joint should develop almost immediately as opposed to a meniscus tear which tends to develop over a few hours. The patient may also hear a ‘pop’ sound or sensation. Subsequently, patient may experience instability of the knee.
- Immediate swelling
- Deep knee pain
- ‘pop’ sound or sensation
- Knee instability
X-Rays and magnetic resonance imaging (MRI) of the knee should be performed to confirm diagnosis. X-rays of the knee is usually normal in patients with an anterior cruciate ligament tear. MRI would usually be indicated to confirm clinical diagnosis of ACL rupture and to evaluate for other injuries such as meniscus tear, cartilage injury and other ligaments injury. MRI is radiation-free and has a very high detection rate.
The treatment for anterior cruciate ligament injury should be individualised according to:
- patient demographics
- associated injuries
All patients with ACL injury should undergo a course of physiotherapy and rehabilitation for strengthening.
Most patients who yearn for a return to sports would usually need ACL reconstruction. ACL reconstruction is performed by knee arthroscopy techniques (keyhole surgery). A graft would be needed to reconstruct the ACL. There are options of autograft (patient’s own tendon) or allograft (donor tendon). There are different considerations for the selection of graft for reconstruction. Your orthopaedic surgeon will discuss it further with you. If there are associated injuries such as meniscus tear or cartilage injuries, your surgeon will also treat the injuries in the same keyhole approach. The surgery will be performed under general or regional anaesthesia. The surgery will take about one hour. You will stay in the ward overnight and be discharged the next day. You may have to use crutches depending on your injuries and surgery. After surgery, you will need physiotherapy for about 9 to 12 months in order to return to competitive sports. Your surgeons will review your condition regularly after surgery to make sure your recovery is on track.