What is ACL Reconstruction?
Anterior cruciate ligament (ACL) reconstruction is a surgical procedure to replace a torn or damaged ACL ligament in your knee with a new ACL tissue graft obtained from your own body (autograft) or in some cases from a deceased donor (allograft).
The most common autografts are the patellar tendon (tendon of the kneecap), quadriceps tendon, or one of the hamstring tendons (tendons located at the back of the thigh). Tendons are cords of strong fibrous tissue that connect muscles to bones. Ligaments are tough bands of tissue that connect one bone to another bone.
ACL tears or injuries most often occur during sports activities that involve pivoting, cutting, and turning movements as in football, soccer, skiing, tennis, and basketball.
Anatomy of the ACL
The anterior cruciate ligament is one of the major stabilizing ligaments in the knee. It is a strong rope-like structure located in the center of the knee, running from the femur (thighbone) to the tibia (shinbone). The ACL is one of the four major ligaments of the knee that connects the femur to the tibia and helps stabilize your knee joint. It prevents excessive forward movement of the tibia in relation to the femur as well as limits rotational movements of the knee. When this ligament tears, unfortunately, it rarely heals on its own and often leads to the feeling of instability in the knee and meniscus damage, requiring reconstruction to correct the abnormality.
Indications for ACL Reconstruction
An ACL tear or injury is the main indication for ACL reconstruction surgery. An ACL injury is a sports-related injury that occurs when the knee is forcefully twisted or hyper-extended. An ACL tear usually occurs with an abrupt directional change with the foot fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down suddenly while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can also result in injury to the ACL. Most ACL tears occur from non-contact mechanisms.
Preparation for ACL Reconstruction
In general, preparation for ACL reconstruction surgery will involve the following steps:
- A review of your medical history and physical examination are performed to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could compromise the safety of the procedure.
- You will be asked if you have allergies to medications, anesthesia, or latex.
- You should inform your doctor of any medications or supplements you are taking or any conditions you have such as heart or lung disease.
- You may be asked to stop taking certain medications, such as blood thinners, anti-inflammatories, aspirin, or other supplements for a week or two.
- You should refrain from alcohol and tobacco at least a few days prior to surgery and several months after, as it can hinder the healing process.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- You should arrange for someone to drive you home after surgery.
- A signed informed consent form will be obtained from you after the pros and cons of the surgery have been explained.
Procedure for ACL Reconstruction
ACL reconstruction surgery is usually performed under general anesthesia in a minimally invasive arthroscopic technique. In general, the procedure involves the following steps:
- Your surgeon will make few incisions around your knee.
- An arthroscope is inserted into the knee joint through one of the incisions.
- An arthroscope is a thin tubular instrument with a camera, light, and a magnifying lens attached at the end that is connected to an external monitor and enables your surgeon to view the inside of the knee joint.
- Along with the arthroscope, a sterile solution is pumped into the joint to expand it, enabling your surgeon to have a clear view and space to work inside the joint.
- Miniature surgical instruments are passed through the other incisions and the torn ACL is removed and the pathway for the new ACL tendon graft is prepared.
- Your surgeon makes an incision over the knee or hamstring area and takes out a part of the patellar, hamstring, or quadriceps tendon to prepare the new ACL graft.
- Small holes are drilled into the upper and lower leg bones (femur and tibia) where these bones come together at the knee joint. The holes form tunnels in your bone to accept the new graft.
- The graft is pulled through the predrilled tunnels in the femur and tibia and fixed into the bones with screws or suspensory devices and anchors.
- After confirming satisfactory reconstruction, the scope and the instruments are withdrawn, and the incisions are sutured and bandaged.
Postoperative Care and Instructions
In general, postoperative care instructions and recovery after ACL reconstruction surgery will involve the following:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic or anesthetic reactions and monitor your vital signs as you recover.
- You may notice pain, swelling, and discomfort in the knee area. Pain and anti-inflammatory medications are provided as needed to keep you comfortable.
- You are advised to keep your leg elevated while resting to prevent swelling and pain.
- You will be given assistive devices such as crutches with instructions on restricted weight-bearing for a specified period of time. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
- Instructions on surgical site care and bathing will be provided to keep the wound clean and dry.
- An individualized physical therapy protocol will be designed to help strengthen the knee muscles and optimize knee function.
- You will be able to resume your normal daily activities in a couple of months, but with certain activity restrictions. Full recovery and return to sports usually take about 9 to 12 months.
- You may return to your work in about 6 weeks if your job is not too physically demanding. Those with physically demanding jobs will require a longer recovery period.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Risks and Complications
ACL reconstruction surgery is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as the following:
- Pain and weakness in the knee
- Adverse reactions to anesthesia
- Blood clot or deep vein thrombosis
- Damage to adjacent soft tissue structures
- Stiffness or decreased range of motion
- Re-rupture of the graft
- Non-healing of the ligament
Commonly asked questions
- How soon after ACL tear do I need surgery? It is recommended that you first work on restoring your full motion and decrease the swelling in the knee. Prehab is important to help strengthen and activate muscles also, which will help in post-operative rehabilitation. Thus, most ACL surgeries are done between 1-4 weeks after injury. If you have a non-operative MCL tear, your surgery may be further delayed to allow the MCL to scar down for 4-6 weeks.
- How long does the ACL surgery take? Surgery can take anywhere between 45 minutes to 2 hours depending on the extent of the damage in the knee and any concomitant procedures. You will likely spend at least 6 hours at the hospital that day with the pre-operative steps, going to sleep with anesthesia, and spending time in the recovery room.
- When should I start physical therapy after ACL surgery? Typically, physical therapy should be started the first day after surgery. It will help reduce swelling, activate muscles, and initiation motion.
- How long do I need to use crutches after ACL surgery? Typically, crutches are used for the first 1-2 weeks to help with mobilization as the quadriceps wakes back up. If there is also a meniscus repair, then crutches are often needed for a total of 6 weeks.
- When can I walk after ACL surgery? If there is no meniscus tear, we usually recommend patients walk immediately after ACL surgery with the use of supportive crutches. Once your quadriceps return in function, you can wean off the crutches, which can take anywhere from 1-3 weeks.
- What can I run after ACL surgery? It depends on the concomitant pathology, but typically once the quadriceps reaches a certain threshold in strength, running can be started as early as 3 months and progressed over the subsequent months.
- When can I drive after ACL surgery? It depends on which knee the surgery was performed. If it is your left knee, then you may return to driving as early as 2 weeks assuming you are off your narcotics. However, if it is your right knee, it may take up to 6 weeks to resume driving. The most important consideration here is that your braking reaction time has normalized.
- When can I swim after ACL surgery? It depends on several factors, but swimming (free-style stroke) after ACL surgery may be done as early as 6-12 weeks.
- When can I return to sport after ACL surgery? Return to sport depends on many factors. In general, we aim to return most athletes to sport gradually between 9-12 months. Studies show that returning sooner than 9 mo may increase your risk for retear of your graft. In addition, the athlete should pass a battery of tests (strength, agility, proprioception) to help decrease the risk of retear.
- Why do I have numbness after my ACL surgery? Mild to moderate numbness on the skin is common after ACL surgery. It is most commonly felt laterally (our outside) portion of the knee and shin area. It can slowly return to normal over months to years.
- Why does my knee pop after ACL surgery? Popping can be felt in the subsequent months after ACL surgery. It can be caused by tissue gliding and the swelling. Non-painful popping is not concerning usually, and will subside over the subsequent months. If the popping is painful, then it may need to be further investigated.
- How does one pick a good surgeon for ACL surgery? Your surgeon should be one who does a high volume of ACL surgery, has a track record of returning patients back to their activity level, and is well versed in how to handle complications. Other things to consider include making sure the surgeon is up to date on the latest techniques and if he or she has published on the topic.