Migration of “bioabsorbable” screws in ACL repair. How much do we know? A systematic review

Purpose Although bioabsorbable screws promise to degrade within months up to several years after implantation, often this did not happen. Actually, other problems such as screw breakage, tunnel enlargement, allergic or foreign body reactions, cyst and abscess formation, and delayed migration of “biodegradable” screws have been reported. This study aims to provide relevant basic science knowledge and recent insights concerning “biomaterials” currently used in fixation devices for anterior cruciate ligament (ACL) repair. A systematic review on the topic of screw “migration” is provided.

Methods A PubMed search combining all the key terms was done aiming for complications related to late migration of “bioabsorbable” screws used in ACL reconstruction without inferior time limitation up to January 2012. Only clinical reports were included. Reference list of reports was checked to detect others not identified by original search. Pre-Publication search was performed to identify the most recent relevant articles.

Results A total of ten articles referred migration of “bioabsorbable” interference screws. Most cases reported to PLLA based screws. Migration was noticed between 3 to 22 months postoperatively. It was noticed both in tibia and in femur and with application of several types of graft.

Conclusions Migration is a possible complication of “bioabsorbable” interference screw. The information related to all clinical implications of the so called “biodegradable screws” remains scarce and probably suffering from a phenomenon of publication bias. It is difficult to reproduce under controlled laboratory conditions the complexity of possible reactions occurring in the human body.

Level of evidence: Systematic Review including case-reports, Level V.