Wrist ligaments: their significance in carpal instability

BACKGROUND: Understanding the exact contribution of the supporting ligaments to the functional integrity of the wrist is crucial for the diagnosis and treatment of carpal instabilities. The present study evaluates functional significance of the wrist ligaments with respect to carpal instabilities. Materials and Methods: Sixteen fresh cadaver wrists were dissected. Extrinsic and intrinsic ligaments of the wrists (ligamentum radioscaphocapitatum, ligamentum radiolunotriquetrum and ligamentum triquetrohamatocapitatum) were sectioned sequentially. After sectioning of each ligament, the wrist was examined for clinical signs of instability such as misalignement of carpal bones, limited range of motion and dorsal translation. When instability was suspected, radiographs were taken and if instability was confirmed, then the ligament was repaired. RESULTS: Although none of the dorsal ligaments sectioning resulted in instability, sectioning of ligamentum scaphotrapeziotrapezoideum, ligamentum radioscaphocapitatum, ligamentum radiolunotriquetrum and ligamentum triquetrohamatocapitatum displayed scaphotrapeziotrapezoidal, dorsal intercalated segment, lunotriquetral and capitohamate instability respectively. In two wrists with arthrosis, sectioning of all ligaments didn’t lead to any instability. CONCLUSION: Instability of the wrist can be classified on anatomical basis after the name of these four ligaments involved i.e. l. scaphotrapeziotrapezoideum, l. radioscaphocapitatum, l. radiolunotriquetrum and l. triquetrohamatocapitatum respectively . This approach clarifies the etiology and treatment of carpal instabilities.