UW Health's Sports Medicine doctors in Madison, Wisconsin, treat a wide range of common athletic injuries, including anterior cruciate ligament (ACL) reconstruction.
Dr. Warren Dunn on the ACL Program
About the Anterior Cruciate Ligament
The anterior cruciate ligament (ACL) is a major stabilizer of the knee joint. The ACL’s primary functions are to prevent abnormal forward translation and rotation of the knee. The ACL can be injured in a number of activities, but cutting, jumping or contact sports cause most injuries. Although isolated ACL injuries are common, it is also possible to injure other knee structures, like cartilage (meniscus) when this ligament is torn.
The ACL is one of four large ligaments stabilizing the knee. It is located deep within the middle of the knee, between the upper leg bone (femur) and lower leg bone (tibia). The posterior cruciate ligament (PCL) is also located in this area. The other two ligaments, the medial collateral and lateral collateral, are located on the sides of the knee joint. The knee cartilages (menisci) are two semicircular pieces of cartilage situated between the femur and tibia. Their function is to act as shock absorbers, and to “deepen” the joint between the rounded surface of the femur and the flat surface of the tibia.
If the ACL is partially or completely torn, the forward movement and rotation of the knee will be greater than normal. Because of this abnormal motion, the knee may “give-out” during sports participation or during daily activities such as walking or turning a corner. Repeated episodes of instability may lead to premature degeneration of the knee joint or injury to the meniscus.
Surgery is not indicated for everyone with an ACL injury. Our recommendations for treatment are always individualized and take into consideration such factors as:
Desired level of activity
Injury to other knee structures
Amount of knee instability
The ACL is usually reconstructed by replacing the torn ACL with the middle third of the patellar tendon or a portion of the hamstrings tendon. At the time of surgery, an arthroscope is used to inspect the knee joint and to repair or remove any meniscal damage. Tunnels are then made in the femur and tibia. If the patellar tendon is used, the central third of this tendon is harvested along with a small amount of bone. The bone ends of the graft are placed in the tunnels so that the graft is in the location of the original ACL, thus replacing the torn ligament. The bone ends are then secured with screws.
After surgery, patients begin exercises for strength and range of motion (ROM). The rate of the rehab progression will depend upon a variety of factors including: the extent of additional injury, other surgery performed, wound healing rate, swelling, muscle tone and ROM. A removable knee brace that locks the knee in a fully extended position is worn for 2–4 weeks.
Initial rehabilitation includes exercises such as straight leg raises, quad sets and ROM exercises. Advanced strengthening exercises such as biking and swimming usually begin at 6–8 weeks; light jogging at 3–4 months. A full return to high demand sports such as soccer, football, basketball, skiing, etc. may take 6–9 months, depending on how quickly the rehabilitation progresses. The physician, physical therapist and licensed athletic trainer will supervise rehabilitation and work with the patient to safely increase activity level.
The goal of the surgery and rehabilitation is to eliminate instability of the knee, decrease the potential for cartilage injuries and safely return the individual to the highest level of activity they desire.