Arthroscopic Primary Repair of the Anterior Cruciate Ligament (ACL)

Hypothesis Null hypothesis: no difference in outcomes between arthroscopic primary ACL repair and arthroscopic ACL reconstruction in patients with acute ACL tear.

Alternative hypothesis: the arthroscopic primary ACL repair is superior to arthroscopic ACL reconstruction.

Background Anterior cruciate ligament (ACL) is an important mechanical stabilizer during knee-joint movement; it is the primary restraint against anterior tibial translation relative to the femur; and it acts as secondary restraint to tibial rotation and varus/valgus rotation. ACL injuries are commonly seen among athletics; and the number is increasing, with a reported incidence of 38/100,000 per year. Although there is still some debate about the optimal treatment for acute ACL tears, surgical management in the young and active patient is recommended. The surgical management options to an isolated ACL tear vary from acute repair to ligament reconstruction. Acute ACL repair can be classified into: acute primary repair, acute repair with the use of a ligament augmentation device, and acute repair with augmentation with an autologous hamstring tendon graft. The outcome of acute repair of ACL rupture from its femoral attachment or a proximal tear close to it, is the aim to be accomplished at the end of this project.

Several studies demonstrated that the results of acute repair of ACL ruptures deteriorate with time and the procedure was shown to be ineffective. However, most of the published studies are retrospective and nonrandomized, and they compare different surgical techniques, rehabilitation, and follow-up protocols. The surgeries were open and lengthy, the repairs were done on all injury types, on wide variety of ages, with varied concomitant injuries, and the rehab was primeval. Furthermore, there is no study that has described the long-term results of acute ACL repair.

Although the concept of ACL potential healing has been deserted in the past, there is renewed interest in the primary healing capacity of this ligament. One would argue why there is a need for the repair of a torn ACL. First, the operation is simple and takes less time and less risk in comparison to ACL reconstruction. Second, ACL treatment aims to provide immediate knee stability; resolve the pain and avoiding long-term complications, primarily osteoarthritis. ACL reconstruction using an autologous or allogenic tendon graft, is universally accepted as the gold standard treatment for complete ACL tears, as it yields excellent results for instability and pain in most the patients. However, there is a higher failure rate in adolescents than in other age groups with up to 20% to 25% of patients experiencing problems postoperatively. This mandates to find a better solution for this group of patients. In addition, patients post ACL reconstructions were found to have higher rates of osteoarthritis, despite the treatment; these findings are based on long-term follow up studies. This emphasizes on the need to find an alternative surgical management option to improve the ultimate outcomes. Third, the incidence of ACL injuries in skeletally immature patients are increasing; and so far, there are no standardized treatment options. For this group of patients, the transphyseal ACL reconstruction with grafts carries a risk for limb length and angular deformities, although several studies have proven no increase in the rate of such complications. Hence, the pre-pubescent population has the potential to benefit greatly from this regenerative treatment, which does not violate the physes; and they respond remarkably to certain biological stimuli implemented in the current enhanced repair techniques. Fourth, regeneration of the ACL over reconstruction preserves the remaining proprioceptive fibers within the ligament substance, and maintains the complex insertion sites of the ligament. This could potentially lead to more normal biomechanics of the knee if adequate regeneration is achieved.