The purpose of this paper is to describe the transverse metacarpal arch (TMA) during a dynamic typing task. Static/relaxed and dynamic typing TMA were collected from 36 right-handed females with musculoskeletal discomfort using a motion capture system. While the angle of right TMA static/relaxed posture (10.1° ± 5.5°) was significantly larger than the left (8.5° ± 5.6°) (P < .05), the right dynamic posture (10.6° ± 4.3°) was not significantly different from the left (10.3° ± 5.5°) (P = .66). Within both these mean scores, there was considerable individual variation, with some subjects demonstrating very flat TMA, and some very curved. The results indicate that TMA angular postures both for static/relaxed and dynamic typing are highly variable both between individuals and between individual hands.
Nancy A. Baker (Corresponding Author) is with the Department of Occupational Therapy, University of Pittsburgh, Pittsburgh, PA. Kaihua Xiu is with the University of Pittsburgh, Pittsburgh, PA. Krissy Moehling is with the Department of Family Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA. Zong-Ming Li is with the Departments of Biomedical Engineering, Orthopedic Surgery, and Physical Medicine and Rehabilitation, Cleveland Clinic, Cleveland, OH.