Definition - osteonecrosis of lunate
Epidemiology - Men > Women, 20-40 y.o., unilateral, hx trauma
Clinical findings - dorsal wrist pain, limited ROM –> increased pain, swelling, decr. ROM, weak grip –> pain at rest
Natural History: necrosis –> trabecular fractures and sclerosis –> collapse and fragmentation –> proximal capitate migration and scaphoid hyperflexion –> ABN carpal motion –> arthrosis
Etiology:
Arterial – variable pattern, patients with a single volar vessel may be predisposed.
Venous – increased venous pressure demonstrated
anatomy – negative ulnar variance (? increased load across R-L articulation)
DX & Staging
Stage I – normal radiographs or linear fracture, abn bone scan, diagnositc MR (decr T1, var T2)
Stage II – Lunate sclerosis, +/- early collaps on radial border
Stage III – IIIA – normal carpal alignment and height (e.g. Gilula’s lines)
IIIB – scaphoid rotation, decreeased carpal height, prox. migration of capitate.
Stage IV – Severe Lunate collapse with intraarticular degenerative changes at the midcarpal joint, radiocarpal joint, or both.
Rx by stage
I – immobilization for up to 3/12
II, IIIA – if neg. uln. variance: joint leveling ( e.g. radial shortening or ulnar lengthening)
- if Inclination >25deg, do closing wedge to reduce.
- if pos. uln. variance: revasc. with 2,3 ICSRA or capitate shortening with C-H fusion or ?STT
IIIB – STT or SC fusion with correction of position of scaphoid
- excision of lunate may decrease synovitis
IV – PRC if head of capitate is intact
- wrist arthrodesis
