The anterior cruciate ligament (ACL) is one of the four ligaments which hold the knee joint together.
These four ligaments are:
- Medial collateral ligament (MCL)
- Lateral collateral ligament (LCL)
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
The collateral ligaments control the side-to-side motion, whereas the cruciate ligaments control the back-and-front movement. In acute ACL injury, the ligament can be either partially or totally torn, and other ligaments and structures, such as the meniscus, joint capsule, articular cartilage, and the ends of the femur and tibia, can also be injured. The athlete’s triad refers to common injuries of the ACL, MCL, and meniscus occurring together.
Symptoms of ACL injury
- Audible pop in the knee and unstable knee at the time of injury
- Swelling due to knee effusion within 2-3 hours after the injury
- Feeling unsteady on the affected knee when walking downstairs, stepping sideways, squatting, or pivoting.
Causes of ACL injury
- Non-contact ACL injuries can occur when you run or jump and suddenly slow down and change direction, causing the knee to bend sideways. It can happen when you play high-demand sports such as soccer, basketball, tennis, gymnastics, or skiing. Women are at higher risk of non-contact ACL injuries than men.
- Contact-related ACL injuries result from a direct blow causing hyperextension. It is when your knee is forced or pushed towards the other leg while playing sports such as soccer, basketball, and rugby.
Diagnosis
- Medical history taking and physical exam
- Imaging tests to assess bones and ligaments
Treatment
Anterior cruciate ligament (ACL) injuries can be treated with surgery, followed by post-surgical rehabilitation.
To determine if surgery is appropriate, your doctor will consider how old and active you are, whether you have had other knee injuries, and whether you can deal with the long recovery process.
Surgery is necessary if:
- Your job requires strong knees for pivoting and turning.
- Your knees are unstable when standing.
- You have meniscal and ACL tears.
- The rehabilitation program does not improve knee stability.
You are required to complete a post-surgical rehabilitation program for 9-10 months. You must commit to the post-surgical rehabilitation program. If you cannot follow the program, you are at higher risk of re-injury, developing scar tissues, and limited knee movement.
Surgery may not be necessary for you if:
- The tear in the ACL is small and can heal with rehabilitation.
- You can participate in and complete a non-surgical rehabilitation program to strengthen the knee muscles.
However, without an ACL reconstruction, you are at a higher risk of developing chronic pain and meniscus injury. The range of physical activities you can do may decrease.
Presurgical rehabilitation
Avoid immediate surgery after an ACL injury because it can cause arthrofibrosis resulting in the limitation of knee range of motion. Your doctor will ask you to wait for 2-4 weeks until the swelling subsides. In the interim, you can relieve pain and swelling with ice pack application and knee elevation above the chest. To increase the knee range of motion and strengthen hip, knee, and thigh muscles, you can do presurgical rehabilitation exercises such as walking, biking, or swimming with light kick motions.
Surgery
For torn ACL, ligament repair is impossible because the blood vessels to the ligament and cells inside the synovial fluid are damaged, preventing the natural healing of ACL. At present, surgical reconstruction is the only way to repair a torn ACL.
You will be given general anesthesia during the 1-2-hour reconstructive surgery. Your doctor will harvest an autograft of a healthy tendon from another area of your leg, such as the patellar, hamstring, or rarely the quadriceps tendon. It is also possible to use an allograft, a tendon from a deceased donor, but in Thailand, we do not have this option yet due to the high cost and risk of infections. Which graft to use for ACL reconstruction depends on your doctor’s evaluation and assessment.
- Patellar autograft: An extra incision is necessary for harvesting a patellar tendon. You may feel the soreness at the graft site for a few months, particularly with kneeling.
- Hamstring autograft: No extra incision is necessary for harvesting a hamstring autograft. The pain is usually less than that from harvesting a patellar autograft. The hamstring can recover within 3-6 months.
Your doctor will use an arthroscope to remove and replace the torn ACL with the harvested graft. Once the graft is in place, your knee will be wrapped in sterile wound dressings and knee immobilizer to prevent joint motion for 1-2 weeks.
After a few hours in the recovery room, you may be able to go home. You will receive instructions about pain medications and a cooling device that wraps around your knee to reduce postoperative pain and inflammation. You will have a follow-up appointment with your doctor 1-2 weeks after surgery.
After a few hours in the recovery room, you may be able to go home. You will receive instructions about pain medications and a cooling device that wraps around your knee to reduce postoperative pain and inflammation. You will have a follow-up appointment with your doctor 1-2 weeks after surgery.
Complications
The most common complications occasionally encountered after surgery or during rehabilitation include
- Arthrofibrosis
- Bleeding into the joint
- Deep vein thrombosis
- Effusion
- Joint infection
- Loosening of the graft
After the surgery
ACL reconstruction is a minimally invasive surgery but a major operation. You must participate in post-surgical rehabilitation for the best outcome.
When surgery is finished, a cast is fashioned over a sterile dressing wrapped around the knee for 1-2 weeks to keep your leg straight and for knee protection. The postoperative pain and swelling during the first few days can be relieved by applying a cold compress and keeping your knee elevated above your chest. In the first week or so, some people can walk with crutches. However, beginning weight bearing on the operated leg as soon as possible is encouraged. Gentle range-of-motion and stretching and strengthening exercises can begin during the first few days after surgery.
