One of the most common sports related injuries today is a rupture to the ACL (Anterior Cruciate Ligament). Just turn on the news or read the newspaper, and chances are at some point you’ll hear about an athlete suffering from this injury. Statistics now show that 250,000-300,000 athletes will experience this painful event each year. An ACL tear can lead to osteoarthritis or another injury to the other knee structures (collateral ligaments, joint capsule, and menisci). So, why is this so common? How can you prevent this injury from occurring? And what are some tips to a successful recovery?
The ACL helps restrain movement in three directions, anterior tibial translation (forward motion of the tibia), valgus and varus (medial and lateral bending of the knee). When the tibia moves anteriorly and/or the femur is directed posteriorly, this develops tension in the ACL. If an additional valgus or varus torque is applied, combined with an internal rotation, generates a greater amount of stress on the ACL. A combination of these forces can cause serious damage to the ACL, and other structures of the knee.
If a major problem can exist when the tibia translates anteriorly, how do we help prevent this? Answer: Hamstring contraction. The hamstrings, located posteriorly on the thigh, consist of three muscles, semitendinosus, semimembranosus, and biceps femoris. These muscles all insert on the posterior tibia, thus pulling the tibia back upon contraction. Strengthening the hamstrings can protect the ACL from additional unwanted tension. Strong hamstring muscles can allow for knee stability and act as a reflex mechanism against anterior tibial translation by pulling the tibia posteriorly.
A simple yet effective exercise for hamstring strength is a hamstring curl. The hamstring curl is a basic flexion at the knee, and no other joints. Hamstring curls for physical therapy can be performed lying prone, face down, and flexing the knee that the heel moves towards the glutes. During this exercise resistance can be added utilizing bands, dumbbells, cables or a machine. Another variation of the hamstring curl can implement an inflatable stability ball. Other hamstring strengthening methods include a variety of deadlift methods, as well as a GHD machine (Glute Ham Developer).
Additional tips to recovering from an ACL injury include:
Swelling, Get Gone!- Another key in range of motion is the amount of edema, swelling, in the knee. To decrease the edema in the joint capsule, follow the old school protocol: Ice, Compression, and Elevation.
Keep Moving- It’s crucial to regain range of motion in the knee post-injury. Immobilizing the knee completely may cause undesirable stiffness in the joint. Mobility is critical before surgery is even required.
Non-weight Bearing- Even though we want to keep the knee moving, non-weight bearing exercise is preferred during the initial recovery phase. Water aerobics is an excellent method of non-weight bearing exercise. A more practical form of exercise is cycling, which is prescribed by physical therapists and can be accommodate various knee flexion complications.
Dave Moseley is a Kinesiologist graduate of Penn State University. His passion for helping people exercise and function properly directly relates to the biophysical knowledge he provides on human movement. In addition, Dave has multiple experiences working with personal trainers, strength coaches, physical therapists, chiropractors, clinical nutritionists and doctors of integrated medicine.