The incidence of anterior cruciate ligament tears in the knees of pediatric athletes is increasing. They occur more frequently in adolescents, but have been reported in children as young as three. Surgery on such young patients presents a dilemma because the patients continue to grow after surgery. Surgeons must carefully consider repair near bone growth plates, as injury to this area impairs proper bone growth.
ACL
The anterior cruciate ligament, or ACL, is one of four ligaments located in the knee joint, which connects the long bones of the leg. The ACL functions as a stabilizer to the knee, minimizing stress across the joint. It is a flexible tissue made of individual collagen fibers. No blood vessels and minimal cells leaves this ligament with no capacity for healing once it's been torn.
Injuries
The causes of torn ACLs include sudden, abrupt changes in force to the knee. Common injuries occur during sudden cutting moves during sports, such as soccer and basketball. ACL injuries usually occur during non-contact sports and are two to six times more likely to occur in girls when compared to boys in the same sport. Athletes say a popping noise is heard prior to the knee giving out, and it swells immediately.
Considerations
Prior to reconstruction, an in-depth physical examination is extremely important. Radiographic images determine a patient's bone age and skeletal maturity by visualization of growth plates. The growth plates of pediatric patients lie near the knee joint, both above and below the joint space. Disruptions of the growth plate area cause reduced and crooked bone growth.
Types of Reconstruction
Treatment depends on the type and severity of the ACL injury. Complete ACL tears warrant reconstruction, otherwise future joint damage causes degenerative changes, leading to arthritis. Three types of ACL reconstruction are available to pediatric patients, but most are not recommended for patients under 12 years. Reconstructions include transphyseal reconstruction, partial transphyseal reconstruction and physeal sparing reconstruction.
Transphyseal Reconstruction
ACL transphyseal reconstruction uses bone tunnels drilled across the growth plates. The tunnels are drilled into the tibia at a 55-degree angle and into the femur at 10:30 or 1:30 clock position. A piece of the patients own hamstring tendon is removed and used as a graft to replace the torn ACL. The hamstring is pulled through each bone tunnel and secured with either bone screws or staples. Both small diameter tunnels and close to vertical tunnel angles prevents growth plate disruption.
Partial Transphyseal Reconstruction
Partial transphyseal reconstruction uses only one bone tunnel. A 6 to 8-mm tunnel is drilled through the tibial growth plate at a more vertical angle than regular transphyseal reconstruction. A hamstring graft is pulled through the tunnel and attached to the tibia. The surgeon uses an over-the-top method to fix the opposite end of the graft onto the femur, avoiding disruption of the femoral growth plate.
Physeal Sparing Reconstruction
The physeal sparing method uses a drilled tunnel through the tibia at an angle that avoids the growth plate. The hamstring graft is threaded through the tunnel and attached to the tibia. A small notch is drilled into the femur, and the other end of the graft is attached to the notch using staples. This technique prevents growth plate damage.
References
- Journal of Korean Medical Science: Transphyseal Reconstruction
- Sports Medicine and Arthroscopy Review: Anterior Cruciate Ligament Reconstruction in the Pediatric Age Group
- The Journal of Bone and Joint Surgery: Physeal Sparing Reconstruction of the Anterior Cruciate Ligament in Children and Adolescents
- The Journal of Bone and Joint Surgery: Transphyseal Anterior Cruciate LIgament Reconstruction
