The ACL or anterior cruciate ligament is one of the 2 major ligaments that keep the knee joint positioned and stable. It is similar to a thick band of tissue having two major strands that extend from the tibia to the femur. The anterior cruciate ligament plays a crucial role in stabilizing the knee by curtailing the anterior translation of the tibia. Tearing of ACL is a common orthopedic injury, athletes and sportsmen are most vulnerable to suffering from it. ACL injuries can cause severe pain, limit the range of motion of the knee, joint instability, cause muscle weakness and alter biomechanics and physical activity.
Statistically, around 60 to 90% of ACL injuries are known to progress into post-traumatic osteoarthritis or PTOA. Several factors can heighten the risk of post-traumatic osteoarthritis after an ACL injury. These factors include the age, gender, body mass index, body weight, level of physical activity, and lifestyle habits of the patient. The interval between the injury and the surgery, any subsequent injuries, and alignment of the knee can also be potential deciding factors.
The development of Osteoarthritis after an ACL injury is mostly the result of initial impact to the subchondral bone and the hyaline cartilage. At the time of injury to the anterior cruciate ligament, the force of trauma disrupts the entire intra-articular structures. After the initial trauma, lack of proper functioning because of ACL deficiency leads to chronic changes in the biomechanics of the knee and increases the pressure on the cartilage and other joint structures. Such intra-articular injuries target the cartilage and the meniscus. These subsequent lesions are the primary reason behind the development of osteoarthritis. This is why in 8 out of 10 cases an acute ACL injury is followed by the development of post-traumatic osteoarthritis.
Another study by NCBI shows that-
Most patients with acute ACL tears are younger than 30 years at the time of their injury. ACL injuries resulting in early onset of osteoarthritis (OA) are often associated with pain, functional limitations, and reduced quality of life. The reported incidence of post-traumatic osteoarthritis or PTOA following an ACL injury was as high as 87%.
A study published in Arthroscopy journal in 2005 showed that the incidence and progression of osteoarthritis or OA over the period of years following anterior cruciate ligament (ACL) disruption in high-level athletes.
The study also stressed on the fact that despite the possibility of returning to high impact activities and sports with a definitive unstable knee and a torn ACL, this may lead in 95% of cases to meniscus tear and cartilage damage over the course of years. In addition, cartilage damage and progressive OA may occur and the patients might require a knee replacement surgery.
Why do ACL tears lead to osteoarthritis?
The risk of early-onset osteoarthritis is significantly heightened after a knee injury, specifically a tear in the anterior cruciate ligament. It is commonly seen that patients who have suffered such injuries develop post-traumatic osteoarthritis. Post-traumatic osteoarthritis or PTOA is a chronic and progressive multifactorial condition that is caused as a result of the impact on the cartilage at the time of an ACL injury, and reactionary inflammation, and altered biomechanics of the joint due to ACL deficiency. Moreover, the concurrent damage to surrounding tendons, cartilage, and meniscus after an ACL tear contributes to the development of PTOA due to which meniscus and cartilage damage are considered to be the first symptoms of the condition.
How to prevent arthritis after ACL injury
Thankfully, there are a few effective and preventative measures that one can take to ward off symptoms of arthritis after an ACL tear. Regular exercise is beneficial for both avoiding and healing ACL injuries. Physiotherapy and exercise therapy can tremendously reduce the chances of early-onset arthritis for people who have undergone ACL reconstruction surgery. For such patients, low-impact exercises like swimming and upper body training are recommended to build core strength, reduce wear and tear to the knee, and give the injury time to heal fully. Regular exercises to train and strengthen ligaments and tendons of legs, hips, and lower abs can help in avoiding ACL injuries in the first place.
Latest research and development
Investigating ways to improve treatment methods is a continuous process, and there are several types of research going on that aim to improve medical issues for young athletes dealing with knee injuries. Some of these investigations include the following.
- Improving the process of ACL Reconstruction Surgery: New surgical techniques have emerged that can help in performing ACL reconstruction surgeries in a more simplified and safe manner. Bridge-enhanced ACL Reconstruction and double-bundle ACL reconstruction surgeries are far better at repairing or replacing damaged ACLs and have a much higher success rate than standard ACL reconstruction surgery.
- Altering joint Biology after injury: After joint injuries like ligament tears, the body releases several chemicals within the joint, thus affecting the joint biology. Altering such chemical responses can help minimize further damage to the joint and ensure optimal healing.
- Preventing injuries to ligaments: Several studies have been conducted to analyze why some people suffer from ligament tears, and what can be done to avoid such injuries for them. It has been observed that neuromuscular training and dynamic control of extreme movements can help prevent knee injuries.
Living with a torn ACL
Some people choose to avoid surgical treatment for torn ACL and decide to live with it. This can be particularly problematic and unsafe for younger people. Once an ACL is torn, the knee becomes highly unstable and buckles in. It becomes weak and is unable to bear any weight. If the tear is left untreated at this point, a chain reaction of secondary damage including meniscus and cartilage tears is set off. This can lead to early-onset osteoarthritis. In some cases, if the tear is not severe, it can be treated with non-surgical methods which include lifestyle changes, physiotherapy, and the use of a knee brace. However, in the case of severe ACL tears, such conservative methods are secondary, and ACL Reconstruction surgery is the only viable solution.
Reconstruction of the ACL
For adults with arthritis, the most commonly accepted treatment route is the replacement of the torn ACL. Such replacements are strong enough to bridge the gap of ACL detachment. The graft is positioned through the center of the knee and is fixed to bones below and above in such a manner that it acts like the original ligament.
For elderly patients or patients with sedentary lifestyles, a cadaver ligament graft is preferred as it offers a quick recovery and reduces pain. However, several reports state the success rate of a cadaver graft is not as high as that of its graft. For younger, more active patients, the use of patellar, hamstring, or quadriceps tendon is considered the best option.
Rehabilitation duration and program vary with the individual needs of patients. In most cases, the rehabilitation period finishes in about three months, and you can return to sports and more demanding physical activities in about 9 months.