Distal complications of Motec® total wrist arthroplasty: failure of osseointegration versus periprosthetic fracture

Failure of osseointegration and periprosthetic fractures are common complications of total wrist arthroplasty. A recent increase in the incidence of the latter is hypothesized to be a result of using larger implants to avoid the former. In this mixed-methods, case-control study of the Motec® arthroplasty, six cases of failure of osseointegration were compared with eight periprosthetic fractures and 14 controls without either problem. Compared with the controls, periprosthetic fractures occurred in younger patients with better bone health and a narrower medullary diameter of the middle finger metacarpal, in which a narrow medullary isthmus was widened to facilitate screw insertion. Failure of osseointegration occurred in older patients with wider metacarpal diameters. It can, however, also occur with over-reaming in younger patients and is more common with off-axis screw insertion. The results of this study suggest that periprosthetic fracture and failure of osseointegration may be opposite ends of a spectrum, with successful osseointegration in between. Both complications should be avoidable with careful surgical technique.<b>Level of evidence:</b> III.