Anterior Cruciate Ligament Reconstruction
What is an Anterior Cruciate Ligament (ACL) injury?
The anterior cruciate ligament is one of the major stabilizing ligaments in the knee. It is a strong rope like structure located in the centre of the knee running from the femur to the tibia. Many activities like sport, work, mountain bike and motorcycle injuries can lead to ACL tears. Common mechanisms include knee hyperextension or pivoting on the planted knee such as when stopping and turning in netball or sideways stepping in soccer or rugby. When this ligament tears unfortunately, it does not heal and often leads to the feeling of instability in the knee. After the injury, the knee tends to swell and become painful and weight bearing may be difficult.
As the knee becomes unstable after ACL injury, other structures such as the menisci bear the load, therefore, meniscal injuries are common after ACL rupture. Meniscal injury can occur during the injury secondary to the trauma or it can occur later due to ongoing instability as the knee continues to give way. Also, depending on the degree of trauma, other ligaments may be affected like the medial collateral ligament (MCL), posterior cruciate ligament (PCL) or lateral collateral ligament (LCL).
This compounds knee instability and multi-ligament knee injuries can be associated with severe knee and limb damage and should be managed as an emergency.
How is ACL injury diagnosed?
The diagnosis is made after clinical assessment. This takes into account the history of the injury and the findings of clinical assessment. Particular clinical tests include the anterior draw test and the Lachman test. Both these tests assess the anterior movement of the tibia on the femur due to ACL insufficiency. Another test is the pivot shift test which attempts to replicate the instability of the knee during pivoting movements due to the ACL rupture.
X-rays are performed to eliminate the occurrence of fracture and MRI is used to assess the soft-tissue around the knee. MRI shows the ACL tear and other potential ligament and meniscal injuries.
What is the initial treatment of ACL injury?
The initial management focusses on decreasing knee swelling and restoring knee range of motion, improving stability and restoring function.
In isolated ACL injuries, weight bearing is usually allowed without crutches, but they may be required for stability or when there is associated injury of other knee structures. Knee swelling is managed with ice packs, supportive braces and compression stocking if tolerated. Physiotherapy is a great initial management modality to regain range of motion and restore gait and normal weight bearing. Physiotherapy also help re-activate the hamstring and quadriceps muscles, especially the VMO (vastus medialis obliquus) component which is important in the final stages of knee extension.
In some cases, the knee becomes stable and function is restored with physiotherapy and the use of a supportive brace, especially during activities that place increased rotational forces on the knee.
In these cases surgery may not be required, but if the patient continues to experience knee instability, swelling, pain or is unable to return to desired activities at work, leisure or during daily living then surgical treatment is possible with ACL reconstruction.
What is ACL reconstruction surgery?
ACL reconstruction is a commonly performed surgical procedure and with recent advances in arthroscopic surgery can now be performed with minimal incision and low complication rates. The surgery uses arthroscopic assistance to prepare the joint and to address any other injuries like meniscal tears which may be trimmed or repaired first. A tendon graft is required for the reconstruction. Most commonly, this is obtained by harvesting two of the patient’s smaller hamstring muscles. Other sources of tendon graft are the central portion of the patella tendon with a piece of bone on either end. The graft is secured in both sides of the tunnel and becomes the reconstructed ACL.
What is rehabilitation like after ACL reconstruction?
Rehabilitation after ACL reconstruction is a lengthy process and takes many months after surgery. Initial recovery after surgery includes physiotherapy to reduce swelling, reactivate the quadriceps and hamstring muscle and restore a normal pattern of weight bearing.
Strengthening exercises gradually commence followed by walking at pace, stationary bike exercises, jogging and eventually running. These activities progress over months and you will be guided by your physiotherapist. Dr Khatib has a recommended timeline for rehabilitation after ACL reconstruction which you can download and take to your physiotherapist.