Dynamic effects of joint-leveling procedure on pressure at the distal radioulnar joint.
OBJECTIVE
Wrist joint-leveling procedures for decompression of the radiocarpal and ulnocarpal joints are accompanied by the risk for subsequent disorders of the adjacent distal radioulnar joint (DRUJ). This study evaluated the dynamic change of the pressure pattern at the DRUJ after joint-leveling procedures.


METHODS
Thirteen fresh-frozen adult cadaveric upper extremities were used. A segment of the radius was excised at its midshaft to allow lengthening and shortening via a mini external fixator attachment. Dynamic pressure sensors were inserted into the DRUJ and the ulnocarpal joint. Axial loads were applied to the extensor carpi radialis brevis, extensor carpi radialis longus, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris for a total of 89 N with or without 30 N of radioulnar loading. The dynamic pressure distribution for full range of forearm rotation was recorded from 6 mm of radial shortening to 6 mm of radial lengthening in increments of 1 mm.


RESULTS
The peak pressures at the DRUJ before the joint-leveling procedures averaged 3.3 MPa without radioulnar loading and 5.0 MPa with radioulnar loading. The peak pressures with axial and radioulnar loading increased 85% at 6 mm of lengthening and only 8% at 6 mm of shortening. The peak pressures at the DRUJ for radial lengthening of 4 mm or more were significantly greater than that of the original length. Pressure at the ulnocarpal joint increased in proportion to the amount of radial shortening and decreased with radial lengthening.


CONCLUSIONS
Radial lengthening but not radial shortening significantly increases the peak pressure at the DRUJ.
Miura
Toshiki
T
Department of Orthopaedics and Rehabilitation, School of Medicine, University of New Mexico, Albuquerque, NM 87131-0001, USA.
Firoozbakhsh
Keikhosrow
K
Cheema
Tahseen
T
Moneim
Moheb S
MS
Edmunds
Mark
M
Meltzer
Sara
S
D000328:Adult; D001696:Biomechanical Phenomena; D002102:Cadaver; D019299:Decompression, Surgical; D005542:Forearm / Q000502:physiology*; D006801:Humans; D019637:Orthopedic Procedures; D011312:Pressure; D011884:Radius / Q000502:physiology; D012399:Rotation; D018709:Statistics, Nonparametric; D014457:Ulna / Q000502:physiology; D014955:Wrist Joint / Q000502:physiology* / Q000601:surgery