[Osteosynthesis using a buttress plate--a new principle for stabilizing scaphoid pseudarthroses].

Deformity with palmar bone resorption can be observed in 20-50% of scaphoid pseudarthroses. A palmar wedge-shaped defect develops after repositioning and debridement of the pseudarthrosis. In the present paper 16 cases in which operations with cancellous bone grafting and palmar buttress plate osteosynthesis in addition were performed are presented. In all but 1, the pseudarthrosis united. All patients were pain-free at follow-up examination a minimum of 9 months (mean 28 months) only slightly reduced. Grip strength and mobility were after operation. The persisting pseudarthrosis necessitated wrist arthrodesis because of radiocarpal arthrosis. Metal slackening with erosion and rupture of the flexor pollicis longus tendon occurred in 1 patient. Palmar buttress plating is a biomechanically consistent form of osteosynthesis. It neutralizes all relevant forces. This means that cancellous bone grafts are sufficient, whereas lag screw or tension band osteosyntheses need cortico-cancellous grafts to resist compression forces. Stability and better chances of healing of pure cancellous bone grafts are the main advantages of palmar buttress plating in scaphoid pseudarthroses.