Preliminary results of an absorbable interference screw

A randomized, prospective multicenter comparison was done of a bioabsorbable interference screw (Bioscrew; Linvatec Corp, Largo, FL) made from poly L-lactic acid and a metal interference screw produced by the same company. Assignment was randomized by sealed envelopes. A total of 110 patients underwent arthroscopic patellar tendon autografts. A minimum 12 months follow-up is available on 85 patients (mean 19 months, range 12 to 33) including 42 with Bioscrews and 43 with metal screws. There were 56 male and 29 female patients. The average age was 29 years (16 to 50 years). Tourniquet times and associated surgical findings were similar for the two groups. Postoperative Tegner and Lysholm scores were not statistically different between the two groups. KT tests at 1 year showed an average 20-lb laxity of 1.8 mm for the Bioscrew and 1.2 mm for the metal screw groups. The average 1-year KT maximum manual side-to-side difference was 1.6 mm for Bioscrews and 1.6 mm for metal screws. A pivot shift was absent in 83% of Bioscrews and 90% of metal screws at follow-up. Six of 85 Bioscrews inserted (7%) broke on insertion (all were 7-mm diameter screws at the femoral site). No additional fixation was required in four cases. In two, the broken screw was replaced. No lytic bone changes or tunnel widening were found with any Bioscrew. One metal screw had tibial tunnel widening. No statistical difference was found between the Bioscrew and the metal screw groups. Short-term data support the conclusion that the Bioscrew is a reasonable alternative to metal interference screws.