Radiocapitate congruency as a predictive factor for the results of proximal row carpectomy.

PURPOSE

To evaluate whether the congruency between the joint surfaces of the lunate fossa of the distal radius and the proximal capitate might be a prognostic factor for functional, clinical, or radiographic results after proximal row carpectomy (PRC).

METHODS

After reconstructing the computed tomographic arthrogram of patients with PRC, we evaluated the shape of the proximal capitate by measuring the radius of curvature of the tip of the capitate. The congruency of the future radiocapitate joint was then evaluated by the radiocapitate index in the frontal and sagittal planes. This was calculated by dividing the radius of curvature of the tip of the capitate by the mean radius of curvature of the lunate fossa. We determined the relationship between these morphological results and the functional (Disabilities of the Arm, Shoulder, and Hand [DASH] score, Mayo Wrist score, and pain relief), clinical (mobility and strength) and x-ray results (radiocapitate arthrosis).

RESULTS

A total of 27 patients were reviewed at a mean follow-up of 59 months. The shape of the proximal capitate did not affect outcomes. In the frontal plane, a better radiocapitate congruency was significantly associated with an increase in wrist flexion and better functional results for the DASH. There was a non-significant relationship between congruency and improvement of Mayo Wrist score and pain relief. In the sagittal plane, the DASH score tended to improve when congruency was better.

CONCLUSIONS

The shape of the capitate was not a prognostic factor for functional outcome after PRC. The radiocapitate index seems more relevant in predicting results at last follow-up.

TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.