Relationship between joint laxity and radio-ulno-carpal joint morphology.

The relationships between wrist laxity, ulnar variance, sigmoid notch inclination, and lunotriquetral motion were analysed in 60 normal volunteers. A strong correlation between ulnar length and sigmoid notch inclination was found for the entire group. Joint laxity was found to correlate with ulnar variance and lunotriquetral mobility in women, but not in men. The greater the laxity, the shorter the ulna and the greater the lunotriquetral motion during radial to ulnar deviation. These results support the concept that laxity increases the vulnerability of the wrist to injury.