LIGAMENTOUS AND TENDINOUS SUPPORT OF THE PISIFORM, ANATOMIC AND BIOMECHANICAL STUDY

Twenty-five formalin preserved cadaveric wrists were dissected and the relationship of the piso-triquetral joint and its surrounding soft ti ssue structures were defined. An additional 4 fresh frozen wrists were examined in longitudinal and transverse sections. These anatomical st udies showed the extensor retinaculum to have a complex insertion into the pisiform, flexor carpi ulnaris, fifth metacarpal, piso-metacarpal ligament, and the abductor digiti minimi muscle. A capsule-ligamentou s structure on the medial aspect of the piso-triquetral joint was also identified. Bio-mechanical testing was performed on 12 fresh cadaver wrists and the results were compared to the anatomical findings to det ermine the contribution of surrounding soft tissue structures to piso- triquetral joint stability. Mechanical testing showed the soft tissues around the piso-triquetral joint to be strongest proximally and dista lly and weakest medially. Transection of the transverse carpal ligamen t resulted in increased lateral motion of the pisiform, but there was no significant decrease in stiffness. This study provides insight into the etiology of piso-triquetral joint instability and dysfunction.