ACL injuries and skeletally immature patients

Though the majority of ACL injuries occur in the adult population, a large, increasing number of youths and adolescents are suffering the same fate, mainly because of over-participation in sports. Many of the relevant factors associated with adult ACL injuries and types of treatment are similar to adolescent ones, but the potential risks involved when dealing with a skeletally immature patient are much more complex and require careful attention. Less is known about the younger age group due to underestimation in injury occurrence, study limitations and the fact that many adult studies also include adolescents.

Upon further inspection, a number of traits thought to be true for the skeletally immature were proven contrary to popular belief. According to a study on reports of ACL injuries and the skeletally immature population, avulsion fractures of the tibial spine remain the most common form of injury to the area, but there are also a far greater number more ACL midsubstance tears than was previously thought. The primary reason for such an abundance of both injuries, especially avulsion fractures, is the immature and underdeveloped ACL. The ACL in the skeletally immature is linked to the tibia and femur at chondroepiphyseal (cartilaginous-growth plate) junctions that eventually become fibrocartilaginous-bone interface when mature. The status of the ligament at this point in maturity leaves it an extremely vulnerable region, resulting in many avulsion fractures and tears. This vulnerability is most directly challenged in the course of athletic competition. One study reported sports injuries as responsible for 70% of acute hemarthroses (bleeding into joint spaces) in children, 67% of which were ACL tears. Furthermore, another documented that 80% of patients aged younger than 12 with hemarthrosis had a tibial spine fracture, with 90% of those older than 12 had an intrasubstance ACL tear.

After diagnosing the injury, when the time comes for treatment, growth plates are again a heavily dependent factor. While non-operative treatments such as physiotherapy, rehabilitation and bracing were believed by many to be efficient, a study that administered these types of treatment to 23 patients led to instability in all and to 10 cases of joint arthrosis. The results caused authors of the study to change their treatment protocol to promote early reconstruction; however, an abundance of early reconstruction options are available, each dependent on the status of physes (growth plates). The options, which include extraphyseal reconstruction, transepiphyseal reconstruction, transphyseal reconstruction and non-operative delayed surgical correction, were all explored in their entirety. Each method takes a distinct approach to growth plates--with some avoiding them entirely, others minimally violating them--while the delayed surgical approach waits until the patient has matured and growth plates have developed. Results showed predominantly positive outcomes for each of the treatment types, but also pointed out potential issues and downsides associated with the respective methods. Transepiphyseal reconstruction is a highly demanding surgery that requires a surgeon who's experienced in the technique, extraphyseal reconstruction will only create temporary relief and will likely lead to future surgery down the line, and delaying surgery too long can also lead to a multitude of problems as well.

Since such a limited amount of literature has been published specifically on ACL reconstruction for patients yet to fully mature, further studies must be performed. This particular study, however, recommends the following: for patients nearing skeletal maturity with a small amount of growth remaining, standard tunnel positioning and soft-tissue graft is the best approach, while younger patients with significant growth remaining should look into procedures that don't intrude on growth plates. Though there are no definite answers just yet in treating ACL injuries for younger age groups, this article should bring to the attention of physicians, athletes and parents of athletes the treatment options available and the necessity of being aware of growth plates from the diagnosing to recovery.

-As reported in the May, '07 edition of Orthopedics

-By Greg Gargiulo