From the Research
Bio interference screws (BIS) used in ACL reconstruction can occasionally migrate through the articular surface, though this is a rare complication, as reported in a case study from 2006 1. Migration typically occurs in less than 5% of cases and is more common with certain screw types, particularly those made from poly-L-lactic acid (PLLA) or polyglycolide materials. Factors that increase migration risk include:
- Improper screw placement
- Inadequate bone quality
- Premature weight-bearing during recovery When migration does occur, it typically happens during the degradation phase of bioabsorbable screws, usually between 6 months to 3 years post-surgery. Patients experiencing screw migration may present with new-onset pain, mechanical symptoms like catching or locking, or effusion. If a screw migrates into the joint space, it can potentially damage the articular cartilage, leading to early osteoarthritis. Surgeons can minimize this risk by ensuring proper tunnel placement, appropriate screw selection based on patient factors, and careful surgical technique. Regular follow-up imaging in the first few years after surgery can help detect early migration before it causes significant problems, as suggested by a study from 2005 2. However, the most recent and highest quality study from 2022 3 does not directly address the issue of screw migration, but it does provide information on the performance of a newly designed anatomical hybrid thread tapered interference screw, which may be relevant to reducing the risk of migration. It is also worth noting that a systematic review from 2016 4 found very low-quality evidence of no difference in self-reported knee function and levels of activity between bioabsorbable and metallic interference screws for graft fixation in ACL reconstruction, but it did suggest that bioabsorbable screws may be associated with more overall treatment failures. Overall, while the evidence is not entirely consistent, the use of bio interference screws in ACL reconstruction carries a small risk of migration, and surgeons should take steps to minimize this risk and monitor patients for signs of migration.