86 – OSTEOLYSIS AND COMPLICATIONS FOLLOWING THE USE OF THE INTERFERENCE BIOABSORBABLE SCREW FOR DISTAL BICEPS TENDON REPAIR

Abstract

Purpose: Anatomic repair of an acute distal biceps tear has been demonstrated to improve flexion and supination strength compared with conservative treatment. The most commonly used fixation methods for a distal biceps tendon repair include suture anchors, bioabsorbable screws, and endobutton. The goal of this study was to

1. perform a radiologic evaluation of bioabsorbable screw tunnel osteolysis and

2. retrospectively review bioabsorbable-screw related clinical complications.

Method: We included twenty (20) consecutive patients who underwent primary anatomic repair of the distal biceps tendon since 2005. We used a 7x23mm biote-nodesis^® screw (Arthrex) in 18 cases, and 8x23mm and 8x12mm screws in the other two cases. First, from the x-ray view done in the immediate postoperative period showing the complete screw tunnel, we measured the ratio of the volume of the bone tunnel to the volume of the radius bone section. A mathematical formula for cylindrical volume was used (¶ x r2 x h). We used a relation between two volumes rather than the tunnel volume itself for scaling purposes. Secondly, we calculated the same relation on the x-ray from the last follow-up. We then obtained the percentage of tunnel enlargement by relating the volumetric ratio from the first x-ray to the ratio from the last x-ray. Afterwards, we performed a retrospective chart review noting any bioabsorbable screw-related and postoperative complications.

Results: In the group, the average age was forty-six (46) years. All subjects were male. Eighteen (18) cases were acute complete ruptures operated in the first three weeks, one case was a partial rupture and one case was chronic (one year). The average follow up was eighteen (18) months. We found that the average initial relative volume occupied by the screw tunnel was 47 % of the bone section. At the last follow-up, this volume increased to 68%. After our chart review, we found that one patient presented with a broken screw and increased pain and that another patient developed a severe foreign-body reaction with re-rupture of the tendon requiring three reoperations.

Conclusion: The use of a bioabsorbable screw for distal biceps tendon fixation results in significant osteolysis of the radial bone at short term follow-up. Consequences of osteolysis in the radius are worrisome since iatro-genic fractures are more likely to occur. Osteolysis can be secondary to an inflammatory reaction to the screw material, bone necrosis secondary to pressure or initial thermal necrosis. We also noted two cases of severe bio-tenodesis screw-related complications among our series of twenty (20) patients. These results call into question the use of the bioabsorbable screw in distal biceps tendon repair and are important to present. Exact volume of bone loss using 3D computed tomography scan analysis as well as quality of life questionnaires and strength testing will be available for presentation.