Decoupling the Wrist: A Cadaveric Experiment Examining Wrist Kinematics Following Midcarpal Fusion and Scaphoid Excision

in Journal of Applied Biomechanics
Restricted access

Purchase article

USD  $24.95

Student 1 year subscription

USD  $87.00

1 year subscription

USD  $116.00

Student 2 year subscription

USD  $165.00

2 year subscription

USD  $215.00

At the wrist, kinematic coupling (the relationship between flexion-extension and radial-ulnar deviation) facilitates function. Although the midcarpal joint is critical for kinematic coupling, many surgeries, such as 4-corner fusion (4CF) and scaphoidexcision 4-corner fusion (SE4CF), modify the midcarpal joint. This study examines how 4CF and SE4CF influence kinematic coupling by quantifying wrist axes of rotation. Wrist axes of rotation were quantified in 8 cadaveric specimens using an optimization algorithm, which fit a 2-revolute joint model to experimental data. In each specimen, data measuring the motion of the third metacarpal relative to the radius was collected for 3 conditions (nonimpaired, 4CF, SE4CF). The calculated axes of rotation were compared using spherical statistics. The angle between the axes of rotation was used to assess coupling, as the nonimpaired wrist has skew axes (ie, angle between axes approximately 60°). Following 4CF and SE4CF, the axes are closer to orthogonal than those of the nonimpaired wrist. The mean angle (±95% confidence interval) between the axes was 92.6° ± 25.2° and 99.8° ± 22.0° for 4CF and SE4CF, respectively. The axes of rotation defined in this study can be used to define joint models, which will facilitate more accurate computational and experimental studies of these procedures.

Nichols is with the Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA; the Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA; and Edward Hines, Jr. VA Hospital, Hines, IL, USA. Bednar and Havey are with Edward Hines, Jr. VA Hospital, Hines, IL, USA; and the Department of Orthopaedic Surgery and Rehabilitation, Stritch School of Medicine, Loyola University–Chicago, IL, USA. Murray is with the Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA; the Departments of Physical Medicine & Rehabilitation and Physical Therapy & Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA; the Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA; and Edward Hines, Jr. VA Hospital, Hines, IL, USA.

Address author correspondence to Wendy M. Murray at w-murray@northwestern.edu.