INTRODUCTION: Arthrodesis of small joints in the hand is an efficacious procedure with well established indications, and yet optimum surgical methods to achieve the goals of a painless, stable, functional fusion remain controversial. The purpose of this report is to describe the use of a new implantable device with unique biomechanical advantages in a series of patients to accomplish small joint arthrodesis.

METHODS: Patients who had had arthrodeses of hand or finger joints using the Twin-Fix screw (Stryker-Leibinger, Kalamazoo, MI) were the subjects of this study. Charts were reviewed retrospectively for standard clinical and demographic data and patients were queried about satisfaction with the chosen procedure. Radiographs of involved joints were obtained at standard intervals and studied for evidence of healing.

RESULTS: Seven joints in seven patients were fused using the Twin-Fix screw. In this series, the indication for fusion was osteoarthrosis in 5 patients and RA in 2. Patients’ operative hands were immobilized for 10-12 days following surgery. Thereafter, the arthrodesis sites were protected with customized splints which could be removed for hygiene purposes, but which also allowed unrestricted motion of the uninvolved joints in the index hand. Time to fusion, judged clinically and radiographically, averaged 8 weeks. Complications were rare and were limited to incarceration of the implant in 2 cases during insertion into the intramedullary canals of phalanges with narrow isthmuses at the diaphyseal-metaphyseal junctions. In those cases, intra-operative modification of the implant was possible and healing progressed uneventfully thereafter.

DISCUSSION: As previous authors have shown, arthrodesis of the hand joints is not without risk and complications. Reported problems include nonunion, malunion, infection, cold intolerance and vascular insufficiency. Retained hardware from plate fixation may cause local tissue irritation and extensor tendon pathology requiring revision surgery. No such complications occurred in this series. The Twin-Fix screw allows separate, independent rotation (not just altered pitch angle) of the leading and trailing threads on the device. That allows surgeon-controlled direct compression across the arthrodesis site. The advantages of the technique and device used in the patients described herein are several: rigid fixation is achieved immediately; early mobilization of uninvolved digits and even uninvolved joints in the involved digit is possible given the rigid fixation and prompt healing response seen; additional procedures and revision surgery for hardware removal are unnecessary. Preliminary results using this device for fusions have been encouraging and warrant continued study.