Will an ACL tear heal itself?
Unfortunately, an ACL tear is not capable of healing itself. Because the ligament is located ‘inside’ the knee joint itself, the normal joint fluid (Synovial fluid) prevents the formation of a blood clot that is needed for ligament healing.b
We now know, that people who continue to have ‘instability’ with an ACL injury, are likely to contribute to irreversible changes within the knee, including meniscal tears and progression to cartilage damage and arthritis.
What is an ACL Reconstruction?
An ACL reconstruction involves replacing an injured/torn ligament with a ‘donor’ tendon. This is typically reserved for ligaments, like the ACL, that are unable to heal themselves, or in situations where the native tissue quality is unsuitable for a direct repair. A ‘Donor’ tendon is a tendon that is taken from another part of the body to substitute for the injured/torn ligament.
In the setting of an ACL reconstruction, the two most common ‘donor’ tendons are:
- Hamstring tendon – one or two
- Patellar tendon – Central third
ACL Reconstruction – Surgical timing?
An isolated ACL injury is not a surgical emergency. In fact, better results are achieved in patients that have had some time (> 2-3 weeks) for the knee to recover following the injury. One of the main concerns with performing this surgery within days of the injury, is the risk of creating surgical scarring which can have permanent effects.
Once the patient has regained range of movement within the knee, and has strengthened up their quadricep muscles, an ACL reconstruction can be performed.
There are special scenarios, such as a concurrent displaced meniscal tear, or a bone avulsion, that may require a more urgent procedure.
ACL Reconstruction – Hamstring Graft
In Australia, the most common type of ‘donor graft’ used for ACL reconstruction is the Hamstring tendons. Traditionally two of the ‘inner’ hamstring tendons have been used for this. More recent techniques only require the use of one hamstring tendon (Semi-tendinosis).
After arriving at the hospital 1-2 hours before your operation, you will be changed into a theatre gown and met my the anaesthetist. The Anaesthetist will discuss your anaesthetic options and tailor a plan to minimise any discomfort. This typically includes the use of a ‘block’ which infiltrates local anaesthetic around sensory nerves.
Dr. Mike Smith performs a hamstring reconstruction of the ACL using only a single hamstring tendon. The potential benefit of this technique is to reduce the degree of hamstring weakness experienced following the procedure.
A small incision is made on the inner part of the upper tibia (‘shin bone’) to harvest the hamstring tendon. The hamstring muscles themselves are left alone. A keyhole arthroscopy is then performed which allows a detailed assessment of the knee joint and treatment of any associated meniscus tears. The hamstring tendon is fashioned into a ‘new ACL’ in preparation for insertion into the knee joint.
Tunnels are fashioned inside the bones of the knee (femur and tibia) which will hold the new ‘graft’ in position. The Hamstring ‘graft’ is then positioned inside the knee joint and held within the tunnels with the use of small screws.
The wounds are closed and a bandage is applied to the leg. You do NOT require a splint following this procedure, and you are able to walk on it immediately. Commonly, you are able to go home the same day of the procedure and will be seen in the clinic 2 weeks later.
ACL reconstruction – Patellar Tendon Graft
The patellar tendon is the tendon that connects your knee cap to your shin bone (‘Tibia’). The central third of the tendon (about 10mm) and small bone plugs, can be used to reconstruct an ACL tear.
The remainder of the procedure is similar to the Hamstring reconstruction technique with the use of an arthroscopy and tunnels within the bones to hold the graft.
There are several different methods for holding the graft in position, including the use of screws, cross pins, or a ‘suspensory’ button
The advantages of a patellar tendon graft include a reproducible thickness of the graft, bone-to-bone healing, and the strength of the graft itself.
ACL Reconstruction – Return to Sport
This is the most common question that Dr. Smith gets asked in relation to ACL injuries. Physiotherapy and rehabilitation is absolutely critical to the success of the reconstruction. The initial focus is on regaining range of movement of the knee and strengthening of the muscles (quadriceps and hamstrings).
Typically you are able to progress to the use of a stationary bike at 2 weeks following the operation. By 3 months you should be able to run in a straight line. This progresses to a detailed plan to return you to your chosen sport. Typically sport specific exercises and non-contact training can be commenced by 6 months. While there is no hard and fast rules as to when you can return to sport, typically it ranges from 9-12 months after the operation.
There is a lot of information to take in regarding an ACL injury and the options for reconstruction and return to sport. Dr. Mike Smith will have a detailed discussion with you regarding the options available, and what management plan is best suited to you personally.