Distal interphalangeal joint arthrodesis with a headless compression screw: morphometric and functional analyses

We performed radiologic measurement of the distal and middle phalanges in volunteers to determine the size of a headless compression screw suitable for distal interphalangeal (DIP) joint arthrodesis in Korean subjects and report on clinical results using an acutrak fusion screw. Radiologic measurements on the distal and middle phalanx were performed to determine the optimal size of screw. Five hundred fingers from 50 adult Koreans without any abnormality on plain radiographs were selected and anteroposterior and lateral radiographs were obtained for measurements. For the distal phalanx, the narrowest diameter of the cortical bone was measured to determine the minimal diameter of the screw that would not penetrate the cortex. For the middle phalanx, the narrowest diameter of the medullary canal was measured to determine the appropriate size of the screw for fixation. Between May 2004 and December 2007, there were 23 fingers in 22 patients (6 male, 16 female) that had finger DIP joint or thumb IP joint arthrodesis performed with the acutrak fusion screws. At the final follow up, time to union, complications, clinical fusion angle, pinch power, visual analogue score (VAS) for pain and the Korean version of the disabilities of the arm, shoulder and hand (DASH) questionnaire were assessed. In the distal phalanx, the narrowest diameter of the cortex was 2.64 +/- A 0.51 mm for the little finger. In the middle phalanx, the narrowest diameter of the medullary canal was 1.83 +/- A 0.50 mm for the little finger and 4.17 +/- A 0.68 for the thumb. The mean time to union was 10 weeks (range 8-12). The mean clinical fusion angle of the DIP joint was 11.9A degrees (range 0-20). The VAS pain score was 0.4 (range 0-3). Pinch power was 75% of the normal side. The average Korean DASH score was 5 points (range 0-8). We experienced one intraoperative fixation failure for thumb IP joint arthrodesis caused by a wide medullary canal of the proximal phalanx. The acutrak fusion screw was a feasible and adequate tool for DIP arthrodesis, particularly in Koreans. However, meticulous attention to technique was important to avoid complications in some little fingers. If preoperative radiographs suggest the thumb has a wide medullary canal, alternate methods of fixation should be considered.