Anterior cruciate ligament (ACL) injury is common in the active population, with the annual inci- dence of reconstructive procedures nearing 300,000 in the United States. The goals of ACL reconstruction are to improve functional outcomes, restore knee joint stability, and prevent subsequent damage to the remaining intra-articular structures. Interference screws are used in bone – patellar tendon – bone ACL graft fixation to allow rigid fixation, facilitate osseous healing, and allow early range of motion. Traditionally, metallic interference screws (MISs) have afforded reliably positive clinical outcomes, prevention of excessive laxity, and low complication rates. MISs promote early integration into bone with high initial fixation strength and have a higher failure load than bioabsorbable interference screws (BISs) in biomechanical studies.
Notwithstanding their established efficacy, a major drawback of MISs is their complicated hardware removal during revision surgery. In recent years a trend away from MIS use has ensued, with a 2013 international survey of orthopaedic surgeons reporting a nearly 3-fold preference for BISs over MISs. BISs dissolve after 2 to 3 years and thus simplify revision. In addition, BISs enable magnetic resonance imaging follow-up because of the absence of artifact. However, complications have been reported with BIS use, including foreign-body tissue reaction against screw remnants, intra-articular screw migration, cyst or abscess formation, breakage during surgery, and bone tunnel widening due to incomplete integration of the bioabsorbable material into bone.
Clinical outcomes and complications have generally appeared similar with BIS use and MIS use in comparative trials and case series. Meta-analyses of available literature recently have been completed with the intent to determine superiority between screw types with respect to clinical outcome scores, knee joint stability or function, tunnel widening, knee effusion, or complication rates. The results of these reviews are mixed, with a spectrum of conclusions ranging from a general lack of most outcome differences associated with either screw type in ACL reconstruction to a significant difference in adverse events with BISs. The authors provide their analyses but allude to the value of use of highemethodologic quality randomized controlled trials in further meta-analyses, as well as a consideration of the proposed benefits with each construct with respect to cost-effectiveness, when providing conclusive recommendations for screw choice.
The purposes of this study were (1) to conduct a systematic review of meta-analyses comparing MISs and BISs in ACL reconstruction, (2) to provide surgical treatment recommendations for ACL graft fixation based on the current best available evidence in the literature, and (3) to propose future research avenues based on areas of practice in which high-level evidence is lacking.