Abstract
Purpose: Carpal instability with scapho-lunate dissociation is still considered to result from the rupture of the so-called scapho-lunate (SL) ligament. Actually, this is not a ligament but a loose capsule allowing flexion of the scaphoid and lunate of very different magnitudes (92° versus 20°. Reconstruction of the SL “ligament” have often provided very disappointing results.
Material: Sections of the SL “ligament” on cadaveric specimens never produce SL dissociation. This dissociation can only occur if the scaphoid remains well-positioned in the articular facette of the radius. Rotory subluxation is possible only if the scapho-trapezotrapezoidal is cut, which allows posterior displacement of the scaphoid. This ligament is not described in anatomy textbooks because it is hidden by the sheath of the palmaris longus. Posterior luxation of the proximal pole of the scaphoid is required for dissociation from the semi-lunate.
Operative method: A reconstruction method for the volar scaphotrapezoid ligament using a band of the flexor carpi radialis tendon was developed on cadaveric specimens before application in 38 patients. The 7-cm band of the palmaris longus tendon, with an intact metatarsal attachment was passed through a tunnel drilled in the distal pole of the scaphoid. The band was then pulled dorsally (correctly positioning the scaphoid) and sutured to the dorsoulnar border of the radius.
Results: Carpal height was restored as was scaphoid-lunate mobility (flexion in radial deviation, extension in cubital deviation). The reduction was maintained at mid- and long-term with prevention of carpal collapse and arthritis. Among the 38 operated patients, 35 achieved full pain relief, three complained of moderate pain under stress. All patients were satisfied.
Discussion: Anatomic research and clinical results confirmed that the scaphotrapezoidal ligmament is the key element for dissociation and its repair.
Conclusion: This operation is currently the only procedure capable of providing easy and definitive repair of carpal instability with scapho-lunate dissociation.
The abstracts were prepared by Docteur Jean Barthas. Correspondence should be addressed to him at Secrétariat de la Société S.O.F.C.O.T., 56 rue Boissonade, 75014 Paris.
