[Corrective Osteotomy of malunited Fractures of the Base of the first Metacarpal Bone].

PURPOSE: In this study, the results after corrective osteotomy of the base of the first metacarpal bone are presented.

PATIENTS AND METHODS: There were 24 malunion following a fracture of the base of the first metacarpal, these included 19 Bennett's fractures, 3 Rolando fractures, and 2 Winterstein fractures. The time between the corrective osteotomy and the initial trauma averaged 16 (range, 4 to 66) weeks. The Bennett and Rolando fractures had an average step-off of 2.3 (range, 0 to 4) mm, as well as gaps between 0.9 and 5.4 mm in the basal articular surface of the first metacarpal. There was a subluxation in 16 patients. Patients with Rolando or Winterstein fractures showed an axis deviation of the first metacarpal ranging from 31° to 57°. Two of the patients with Rolando fracture showed a step-off of the articular surface of 1 and 3 millimetres, respectively. Screw osteosynthesis was carried out 10 times, K-wire osteosynthesis 13 times, and once, both procedures were combined. One osteotomy was performed with use of a plate osteosynthesis.

RESULTS: The corrective osteotomy in patients with Bennett's fracture improved the radial abduction on average from 37° to 49° and the palmar abduction on average from 37° to 47°. Thirteen patients presented a congruent articular surface postoperatively. A step-off in the articular surface between 0.5 and 2.2 millimetres remained in 6 cases. In one patient the subluxation could not be completely corrected. In two cases a trapezectomy was required due to the remaining displacement in the joint and a post-traumatic osteoarthritis. The mobility after Rolando and Winterstein fractures improved on average from 31° to 41° for radial abduction and from 32° to 43° for palmar abduction. Congruent joint surfaces as well as repositioning of the first metacarpal was seen in all patients, only one patient showed a persisting axis deviation of 35° postoperatively. All patients returned to work.

CONCLUSION: The study shows that posttraumatic malunion of the base of the first metacarpal can be treated effectively by corrective osteotomy resulting in good outcomes, if degenerative changes have not occurred, while alternative treatment methods remain to be performed.