The migration of a BioScrew® as a differential diagnosis of knee pain, locking after ACL reconstruction: a report of two cases

Introduction: Problems with the initial fixation strength and widening of the femoral and tibial canal after ACL reconstruction using a triple or quadruple semitendinosus autograft have led to the introduction of the so-called Hybrid fixation with the additional use of interference screws. Pain and intraarticular migration have been reported with metal interference screws requiring implant removal (Am J Knee Surg 11:32–34, 2000, Arthroscopy 11:289–291, 1995) but not yet with bioabsorbable screws. Materials and methods: We report on two cases were the intraarticular position of a bioabsorbable interference screw possibly due to migration in the early postoperative period lead to symptoms, the need for further surgery, and implant removal. Results: A preoperative MRI revealed the diagnosis. After removal of the tibial interference screw both knees were settling down, albeit with residual instability and only a moderate clinical result. Discussion: Despite the attractiveness of bioabsorbable screws due to the very fact that they are being reabsorbed over time, there is a slight risk of migration in the first month after the operation. In any suspicious case an MRI will easily clarify the diagnosis.