Quantitative assessment of the midcarpal shift test

Area of Science:

• Orthopedics
• Biomechanics
• Hand Surgery

Background:

• Midcarpal instability is a condition affecting wrist function.
• The clinical midcarpal shift test is a subjective assessment for this condition.
• Quantitative methods are needed to validate clinical assessments.

Purpose of the Study:

• To compare the subjective midcarpal shift test with quantitative carpal translation measurements.
• To validate the clinical test's diagnostic utility for midcarpal instability.
• To explore the potential of a mechanical testing system as a biomechanical marker.

Main Methods:

• A mechanical testing system simulated the clinical midcarpal shift test.
• The system measured carpal translation (volar/dorsal) against ulnar deviation under a constant axial load.
• Testing was performed on healthy volunteers and patients with diagnosed ulnar midcarpal instability.

Main Results:

• Higher grades of clinical laxity correlated with higher maximum slopes on the carpal translation vs. ulnar deviation curve.
• The point of observed 'clunk' during the test showed a trend correlating with laxity grade.
• Quantitative measurements supported the clinical findings, confirming test validity.

Conclusions:

• The clinical midcarpal shift test is a valid and useful diagnostic tool for midcarpal nondissociative carpal instability.
• The mechanized test provides a biomechanical marker for assessing carpal laxity.
• This research validates a clinical assessment using objective biomechanical data.