[Irreducible palmar dislocation of the metacarpophalangeal thumb joint by a skiing accident].

Amongst the large number of severe sprains of the lateral ulnar ligament of the metacarpophalangeal joint of the thumb by skiing accidents which we treat each year as a result of our geographical situation, we have encountered an original lesion on two occasions. The patients were referred with unstable palmar dislocation of the metacarpophalangeal joint of the thumb despite an attempt of reduction under local anaesthesia performed at the ski resort by practitioners particularly well trained in this form of traumatology. On examination, the thumb was globally painful and presented a defect of active extension of the MP joint suggestive of a complex lesion of the extensor apparatus. X-rays showed palmar dislocation of the MP joint of the thumb. Surgical exploration in both cases revealed identical lesions: complete rupture of the two bundles of the lateral ulnar ligament of the MP joint of the thumb, whose distal extremities could be seen as soon as the skin was opened with incarceration of the extensor apparatus between the palmar surface of the neck of the first metacarpal and the dorsal surface of the first phalanx. Perfectly classical treatment consisted of a dorso-lateral incision to reduce the extensor apparatus and to suture the two bundles of the lateral ulnar ligament; immediately restoring the stability which is usually observed in "classical" severe sprains. The current result is good, entirely comparable to that of severe sprains of the MP joint of the thumb.(ABSTRACT TRUNCATED AT 250 WORDS)