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Prediction of Optimal Proximal Interphalangeal Joint Fusion Angle Using Simulated Joint Arthrodesis
Yevheniy Lider, BS, Mitchell Fourman, M.Phil, Karen DeChello, MS, OTR/L, Arjun Iyer, BS, Sue Sisto, PhD, PT, FACRM, Alexander Dagum, MD.
Stony Brook University Medical Center, Stony Brook, NY, USA.
Arthrodesis is a common surgical treatment for arthritis of the proximal interphalangeal joint (PIPJ); however, few studies have investigated the functional impact of the loss of mobility within the joint - as a result, the selection of the angle at which to fuse the PIPJ is based on the surgeon’s personal experience. In this study, we comprehensively investigate the effects of index PIPJ fusion at several angles on hand performance, hand motion, and subjective perception with the goal of identifying the optimal fusion angle.
In a randomized trial, a battery of hand function tests were administered to healthy participants whose index PIP joints have been splinted at specific angles(30°,40°,50°,60°). For each of the four splinted conditions and one unsplinted control, each participant performed the Purdue Pegboard Dexterity Test, the Jebsen-Taylor Hand Function Test, and a pulp-to-pulp pinch dynamometer while the kinematics of the upper extremity was measured using a motion capture system. The Michigan Hand Questionnaire, QuickDASH, and a custom survey were administered to measure the perceived impact of the simulated fusion. Statistical analysis was performed using the Friedman test and Wilcoxon signed-rank test. P<0.05 was considered significant.
Data were collected for 14 participants who attained the mean scores of: 16.0(SD=1.5), 14.3(SD=1.7), 14.5(SD=2.3), 14.0(SD=2.4) 13.6(SD=2.1) for the pegboard task, 10.0(SD=2.2), 8.98(SD=1.7), 9.38(SD=1.9), 9.65(SD=1.7), 9.17(SD=2.2) for the pinch strength test, and 44.7(SD=6.5), 49.0(SD=5.8), 50.6(SD=5.7), 49.2(SD=5.5), 49.1(SD=5.3) for the Jebsen-Taylor test during the unsplinted, 30°, 40°, 50°, and 60° conditions respectively. A learning trend was observed and the data were normalized using the group average for each trial prior to statistical analysis. Participants performed best while splinted at 40° during the pegboard task, 50° during the pinch strength test, and 30° during the Jebsen-Taylor task. No significant difference has been observed among the splinted conditions for the pegboard and Jebsen-Taylor tasks, but has been observed for the pinch test. Significant difference in pinch strength has been observed between the angles of 30° and 50° (t=-2.277, with df=13, P=0.048).
Preliminary performance data (N=14) suggests that optimal angle depends on the task and is trending toward an optimal angle of 40° for the pegboard task and 50° for the pinch. For the 50° condition, pinch strength did not significantly differ from unsplinted condition, indicating little loss in pinch strength at that angle. Gross functional tasks as measured by the Jebsen-Taylor assessment do not appear to be significantly affected by varying splint angles. This may be due to the relatively simple motion required for the completion of the tasks and the ability of the subject to compensate. Secondary analysis revealed that best-performing angles differed between subjects, suggesting that optimal angle may be a function of individual factors such as hand geometry.
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