Capitolunate Fusion for SLAC and SNAC Wrist: How Do Nitinol Staples Perform Relative to Screws?
Richard Mcknight, MD1; Mark Tait, MD2; John Bracey, MD2; Susan M. Odum, PhD3; Daniel R Lewis, MD4; Glenn Gaston, MD4
1Atrium Health, Charlotte, NC, 2University of Arkansas for Medical Sciences, Little Rock, AR, 3OrthoCarolina Research Institute, Charlotte, NC, 4OrthoCarolina Hand Center, Charlotte, NC
Introduction: There is a renewed interest in capitolunate arthrodesis (CLA) for scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrist. While headless compression screws are the main method of fixation, nitinol memory compression staples show promise as an effective alternative. The purpose of this study was to compare the clinical outcomes and complications of CLA for SNAC or SLAC wrist treatment using either compression screws or nitinol staples. We hypothesized that nitinol staples would have similar clinical outcomes and complications to headless compression screws.
Materials & Methods: All patients with SNAC or SLAC deformities who had CLA or capitolunohamate arthrodesis with screws or nitinol staples by a single surgeon over the last 10 years were identified retrospectively. Patients were grouped by fixation type. Primary outcome was fusion on radiographs and/or CT. Secondary outcomes were hardware-related complications (HWC) and other complications. Functional outcomes included range of motion (ROM) and grip strength. Patient-reported outcomes (PROM) included visual analogue scale (VAS); Disabilities of the Arm, Shoulder, and Hand (DASH) score; and patient-rated wrist evaluation (PRWE). Information was also collected on demographics, concomitant procedures, and need for additional surgery.
Results: 40 of 47 (85%) eligible patients were included. 31 patients in the staple group and 9 patients in the screw group. 3 patients declined to participate and 4 patients lost to followup. Average age was 49 years old (17-80). Two patients in the staple group received capitolunohamate arthrodesis, while all other patients were CLA. Mean follow-up was 15.6 weeks (10.5 – 37). There was a 100% union rate overall. Two patients (22.2%, 95% CI .6%-.55%) in the screw group had the HWC of screw backout. One had delayed union and the other reoperation for hardware removal. There were 2 (6.5%, 95% CI 2%-21%) HWCs in the staple group. One patient had staple loosening requiring revision fusion, and the other dorsal impingement and stiffness requiring staple removal and capsulotomy. The patient with dorsal impingement was the primary surgeon's first case with nitinol staples. In all subsequent cases the staples were countersunk. There were no significant differences in any functional outcomes or PROMs (Table 1).
Conclusions: In our limited series, we found no clinical significant differences between compressive nitinol staples and screws for CLA.
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