Metacarpophalangeal hyperextension in trapeziometacarpal osteoarthritis: Relationship to first metacarpal head shape, and clinical impact
Abstract
PURPOSE: The aim of this study was to determine whether the shape of the first metacarpal head influences metacarpophalangeal hyperextension, and to evaluate the influence of metacarpophalangeal hyperextension on hand pain and function in patients with trapeziometacarpal osteoarthritis.
METHODS: 362 patients with painful basal thumb osteoarthritis were evaluated over a 2-year period. Pain rating on a visual analog scale, trapeziometacarpal and metacarpophalangeal motion, and grip and pinch strength were evaluated. The shape of the metacarpal head was assessed on strict lateral radiographs using the "A/r" ratio.
RESULTS: Round metacarpal heads had significantly greater and more frequent metacarpophalangeal hyperextension than flat heads (28° vs. 8°, and 78% vs. 29%). Metacarpophalangeal hyperextension adversely impacted trapeziometacarpal motion in antepulsion (27° vs. 32°), abduction (25° vs. 30°) and pinch strength (3.6 vs. 4.6 KgF).
CONCLUSION: Our findings indicate that the shape of the metacarpal head influences metacarpophalangeal hyperextension in trapeziometacarpal osteoarthritis. Metacarpophalangeal hyperextension adversely impacted pinch strength and trapeziometacarpal motion.
LEVEL OF EVIDENCE: Level IV, Retrospective case series.
How strong is the evidence?
Evidence Hub reads this as a case series, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health. Reported size: 362 participants or records.
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