Criteria for Return to Play After Anterior Cruciate Ligament Reconstruction

Introduction

Modern surgical techniques and rehabilitation protocols have led to improved surgical outcomes following anterior cruciate ligament (ACL) injury and have made return to play (RTP) a realistic goal for athletes. The incidence of anterior cruciate ligament reconstruction (ACLR) surgery has been increasing in recent decades, and the desire to return to preinjury activity levels acts as a motivator for surgery in many patients. Ardern et al. reported that 81% of people return to any sport following ACLR, and 65% return to preinjury level of activity after surgery. After ACLR, it is certainly possible for athletes in a variety of sports to successfully RTP ( Table 119.1 ). However, significant controversy remains regarding RTP criteria, which is influenced by preoperative, intraoperative, and postoperative factors.

Preoperative Factors Affecting Return to Play

Following ACL injury, the ideal timing for ACLR is when the patient has regained full range of motion (ROM), typically 1–4 weeks after injury, or as early as 2–3 days after injury with aggressive rehabilitation. Preoperative rehabilitation should begin as soon as possible after injury, since regaining complete ROM while limiting quadriceps and hamstring atrophy may accelerate RTP and avoid postoperative complications after ACLR surgery. If ROM is not fully restored prior to surgery, patients face a greater risk of arthofibrosis, which may limit terminal extension, terminal flexion, or more commonly, both. Arthrofibrosis can lead to progressive joint degeneration by interfering with native biomechanics and ROM, and it can affect gait, athletic performance, and contribute to increased risk of osteoarthritis by increasing patellofemoral joint contact pressures. The timing of surgery has previously been emphasized as the primary factor in preventing arthrofibrosis following ACLR; however, the importance of regaining terminal knee extension and full ROM prior to ACLR is now understood to be significant in preventing postoperative arthrofibrosis.

Intraoperative Factors Affecting Return to Play

Of the two general categories of grafts for ACLR, autografts, and allografts, neither is clearly superior to the other with respect to retear rates or clinical outcomes, although some authors have suggested differences in the biological incorporation and mechanical properties. In addition, multiple authors have noted that allograft incorporation and survival may be related to graft processing techniques. When interpreting the literature on RTP following ACLR, it is critical to be aware of the type of grafts, the graft processing protocols (for allograft), and the patient population studied.

ACLR with autograft can be performed with bone–patellar tendon–bone (BPTB), hamstring, or quadriceps tendon grafts, with BPTB grafts being the most common graft choice. Compared with BPTB allograft, some authors have found that BPTB autograft demonstrates lower graft rupture, failure, and complication rates, while demonstrating superior bone-to-bone healing, subjective outcomes, and objective outcomes, including high RTP rates. A meta-analysis by Mascarenhas et al. with a total of 15,819 patients found no differences in rupture rates and clinical outcomes between autografts and allografts in ACLR. Studies that have shown BPTB allografts to be inferior to BPTB autografts did not standardize for graft processing, surgical technique, and rehabilitation protocols. Therefore, as stated previously, there is not conclusive evidence on the superiority of either graft type.

While patellar tendon autografts and allografts both heal via bone-to-bone, which is considered faster than soft-tissue healing, allografts have a slower rate of biologic incorporation. Jackson et al., compared characteristic indicators of healing status between BPTB allograft and autografts in an animal model. At 6 months following surgery, the autograft had healed significantly faster than the allograft, resulting in improved stability and increased maximum force to failure values, suggesting decreased failure rates. In contrast, Nikolaou et al. compared the strength, histology, and revascularization of patellar tendon allograft and autografts in an animal model. Both grafts achieved mechanical integrity similar to one another by 36 weeks of healing. Given the overall seemingly faster rate of graft incorporation with patellar tendon autograft, ACLR with BPTB autograft has long been considered the gold standard for competitive, high-level athletes with ACL injuries wishing to return to play.

Concerns over potential complications associated with ACLR with BPTB autograft, including extensor mechanism complications and postoperative anterior knee pain, have led to an increased utilization hamstring autografts. Most often, the hamstring autograft is fashioned as a four-strand configuration, with superior biomechanical properties compared with patellar tendon graft, which may in theory be beneficial for some athletes. Wipfler et al. performed a prospective randomized-controlled trial of hamstring autograft versus BPTB autograft with 9-year follow-up. International Knee Documentation (IKDC) scores were significantly better at follow-up in the hamstring tendon group; however, clinical and functional outcomes, including ROM, KT-1000, and pivot-shift testing, showed no significant differences between the two groups. Isokinetic testing revealed near-normal quadriceps strength testing in both groups; however, hamstring strength was predictably lower in the hamstring allograft group.