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[Perilunate progressive instability of the wrist: a study of wrist dynamics]
1Department of Hand Surgery, Affiliated Hospital of Nantong Medical College, Nantong 226001.
Objective:
To study the changes in dynamics of wrist motor tendons after perilunate instability of the wrist.
Methods:
14 cadaver upper extremities were used. Excursions of the principle wrist and finger motor tendons were measured during wrist flexion-extension and radiolunar deviation was determined. Data were collected in the intact wrist, then in the wrist with stage I, II and III perilunate instability. The average moment arms of the tendons during wrist motion were calculated.
Results:
The moment arms of the wrist flexors increased and those of the finger flexors decreased after instability. Increase in the moment arms dominated changes of radial side wrist motors, while decrease in the moment arms dominated ulnar wrist motors. Moment arms of the flexor carpi radialis tendon showed a consistent increase during wrist motion.
Conclusion:
The changes in wrist dynamics play an important role in clinical manifestations of perilunate instability. The significance of kinetic information on principle of treatment of the instability is discussed.