ACL InjuriesFrequently asked questions about ACL reconstruction
A basic understanding of Knee anatomy can be obtained here. BackgroundThe anterior cruciate ligament (ACL) is one of the main restraining ligaments of the knee (see anatomy). The ACL is sited in the centre of the knee and runs from the back of the femur to the front of the tibia and acts to prevent excessive forward movement of the tibia. The Anterior cruciate ligament’s main role, however, is to keep the knee stable during rotational movements like twisting, turning or side-stepping activities. Injuries to the ACL typically occur during a non-contact twisting movement and a popping sensation can often be felt or heard. Immediate swelling often occurs due to bleeding into the knee (a haemarthrosis). Other injuries to the knee can occur at the same time including meniscal tears (cartilage) or damage to the joint surface. The ACL also provides important information to the muscles around the knee (proprioception), which are involved in protecting the knee during activities. These ‘balancing’ mechanisms are reduced when the ACL is injured although some of this function can be restored with an appropriate exercise programme supervised by a sports physiotherapist. If the ACL is torn the knee is likely to give way with twisting activities and if this is associated with knee swelling, it is likely that damage has been done to the joint surface and/or meniscal cartilage. Continued damage will eventually result in osteoarthritis.
Anterior Cruciate Ligament (ACL) SymptomsThe symptoms of patients with an injury to the ACL include a feeling of instability or giving way. They may involve swelling and pain. Typically this will be with twisting activities, however a small proportion of patients become so unstable that even simple activities may cause giving way. There are also a small proportion of patients who are able to return to pivoting activities without giving way. Anterior Cruciate Ligament (ACL) DiagnosisA ruptured ACL can normally be diagnosed from the history of the injury and confirmed with specific tests at the time of your examination. The diagnosis can be difficult in some cases (especially fresh injuries where examination may be too uncomfortable and those with other injuries to the knee); in these cases the diagnosis can usually be confirmed by MRI scan. A torn ACL cannot be seen on x-ray. Anterior Cruciate Ligament (ACL) TreatmentSurgery is not required for all ACL injuries. Some patients with this injury choose to alter their lifestyle in order to avoid activities which make the knee give way. A small proportion of patients are able to continue with their activities without major problems. These "copers" are typically (but not always) patients with lower physical activity levels, who do not participate in pivoting/twisting activities. Anterior Cruciate Ligament (ACL) Non-operative treatmentConservative treatment of an ACL injury involves a supervised physiotherapy programme concentrating specifically on:
Functional Knee Braces are sometimes prescribed to help patients with damaged ACL’s. Their benefits are not fully understood although they may help with proprioception (see above). They are expensive and may not provide much in the way of support to knee stability. Anterior Cruciate Ligament (ACL) Surgery
Following an ACL rupture your surgeon may decide, after discussion with you, that reconstruction is appropriate. ACL reconstruction is the commonest ligament reconstruction performed around the knee. ACL reconstruction is an attempt to replace the stabilizing function of the anterior cruciate ligament. The ACL reconstruction procedure involves removing the remains of the damaged ACL and replacing it with another form of soft tissue, called a graft. A number of grafts are available for use to replace the ACL. The two commonest graft techniques are to use two “hamstring tendons” – the semitendinosus and gracilis muscle tendons – or a so called BTB (bone tendon bone, or patella tendon graft). The preference of the Yorkshire Knee Clinic Surgeons is to use hamstring grafts as first choice. The evidence in the medical literature is that there is little or nothing to choose between these two main grafts in terms of results. Other grafts are available in more unusual situations.
Anterior cruciate ligament reconstruction is usually performed using arthroscopic (keyhole) surgery. There is however a small (4 to 5 cm) incision below the knee where the tendons for the graft are harvested from. The basic technique of anterior cruciate ligament reconstruction is to identify the correct insertion points on the femur and tibia for the ACL. At these insertion points tunnels of an appropriate size to match the graft are drilled through the bone. The graft is then pulled up through the bone and is secured using either screws, pins, staples or other specialised anchoring devices. ACL reconstruction may be performed either as day case or overnight surgery. In patients who are having the operation for appropriate reasons and who comply with rehabilitation (6-8 months), there is a 90 to 95% chance of a good result: that is, where stability is restored enough for the patient to undertake activities, including sports, that they were previously unable to. Complications include infection (<1% significant), nerve damage (a numb patch of skin, quite common over a small area, but rarely a problem), stiffness (uncommon) and failure of the graft due to re-injury or unexplained failure. Related topic > Rehabilitation |
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A diagram of knee anatomy
