The anterior cruciate ligament (ACL) is a band of connective tissue located in the center of the knee joint, connecting the thigh bone (femur) to the shin bone (tibia). It plays a role in stabilizing the knee by preventing the shin bone from sliding too far forward and limiting rotational movements. ACL tears are common, with estimates ranging from 100,000 to 200,000 injuries annually in the U.S., particularly among athletes. While surgical repair is a frequent treatment option, some individuals choose not to undergo surgery. This article explores the consequences and management strategies for an unrepaired ACL.
The ACL’s Function
The ACL’s main function involves preventing the tibia from shifting too far forward relative to the femur. It also helps to limit excessive rotation of the tibia, especially internal rotation, and restricts hyperextension of the knee joint. These roles are particularly important during activities that involve pivoting, cutting, or sudden changes in direction. Along with other knee ligaments, the ACL contributes to the knee’s stability.
Immediate Effects of an Unrepaired ACL
When an ACL is torn and not repaired, individuals experience immediate consequences affecting knee function. A common symptom is a feeling of “giving way” or buckling, particularly during pivoting, twisting, or sudden stops. This instability can make it difficult to maintain balance and may lead to falls. Many also report hearing or feeling a “pop” at the time of injury, followed by rapid swelling and pain. Initial pain can be severe, with a loss of full range of motion, making walking difficult.
The feeling of looseness impacts confidence in knee stability. This can discourage participation in certain activities due to the risk of the knee giving out. Even simple daily tasks, such as walking or climbing stairs, can be affected by persistent instability and discomfort. While initial pain and swelling may subside, the underlying mechanical instability remains without repair.
Long-Term Health Risks
Not repairing a torn ACL carries long-term health risks due to altered mechanics and increased stress on the knee joint. A primary consequence is an increased risk of developing osteoarthritis, a condition characterized by the gradual wearing away of protective cartilage. This degenerative process can lead to chronic pain, stiffness, and reduced mobility. People with ACL injuries have a higher risk of developing knee arthritis, even with surgical repair, but this risk is amplified without it.
An unrepaired ACL also heightens susceptibility to secondary injuries within the knee. Instability can place abnormal stress on other structures, leading to tears in the meniscus, which acts as a shock absorber, or damage to other ligaments and articular cartilage. Meniscal tears are common in ACL-deficient knees, and these secondary injuries further contribute to osteoarthritis progression. Cumulative damage from recurrent instability can accelerate joint deterioration, potentially leading to the need for more invasive treatments like total joint replacement.
Living Without ACL Repair
For individuals who choose not to repair a torn ACL, managing the knee involves non-surgical strategies to compensate for the ligament’s absence. Physical therapy is a central component, focusing on strengthening muscles around the knee, particularly the quadriceps and hamstrings. Strengthening these muscles improves knee stability and control, reducing episodes of the knee giving way. Exercises progress from basic range of motion and isometric contractions to more complex balance and agility drills.
Another strategy involves knee braces, which provide external support and stability, especially during physical activity. These braces limit unwanted knee movements and may be recommended for those returning to sports or activities involving pivoting. Activity modification is also common, where individuals adjust their lifestyle to avoid movements or sports that provoke instability. While some may participate in certain activities, high-impact sports involving frequent twisting or cutting movements might need to be avoided or approached with caution. The decision to forgo surgery depends on an individual’s activity level and willingness to commit to a rigorous rehabilitation program and potential lifestyle changes.