Evaluation of a shape memory staple (Qual) in radial shortening osteotomy in Kienböck's disease: A retrospective study of 30 cases.

The QUAL (Memometal, Stryker) device is a shape memory staple used for bone fixation during distal radius shortening osteotomy in the context of Kienböck's disease. The present study is a retrospective, single-center and multisurgeon study of 30 patients with a mean follow-up of 8 years. Clinical criteria (range of motion (ROM), strength, pain and functional score) and radiographic data (ulnar variance, distal radius articular surface inclination, Lichtman stage, carpal height and bone healing) were evaluated pre- and post-operatively. We found satisfactory results with the mean grip strength of 22 kg/F before surgery and 24 kg/F after surgery. The mean ROM was 88° preoperatively and 82° postoperatively and the mean ulnar deviation was 23° preoperatively and 21° post-operatively. There was no change in radial deviation and pronation-supination after surgery. The average ulnar variance was 1 mm before surgery and 0.2 mm after surgery. The inclination of the distal radius articular surface on lateral and anteroposterior views and the mean carpal height were similar to the pre-operative ones. There was no delay in bone healing. The mean pain score was 2 at rest on a visual analogue scale after surgery. Seven patients experienced an increase in their Lichtman stage at the follow-up, and two patients were waiting for conversion to a non-conservative surgical treatment. Seven staples were removed postoperatively. Seventy-eight percent of patients returned to work after 3 months on average. Seventy-five percent of patients were at least satisfied with the outcome of their surgery. The QUAL staple is a reliable option for fixation during shortening osteotomy of the radius in Kienböck's disease.