Scaphotrapeziotrapezoid arthrodesis for isolated osteoarthritis: results at a mean 8 years' follow-up.

The aim of this retrospective study was to report medium- to long-term outcome of scaphotrapeziotrapezoid (STT) arthrodesis with staple fixation to treat painful isolated osteoarthritis (OA). Twenty-one consecutive patients (22 wrists) who had undergone STT arthrodesis were retrospectively reviewed by an independent examiner. Clinical and radiological evaluation was performed. At a mean follow-up of 8 years (range 2-20 years), pain levels were significantly decreased, and functional scores were significantly improved. Grip and pinch strength were 86% and 82% of those of the contralateral side. Wrist range of motion in flexion-extension and radial-ulnar deviation was significantly less than on the contralateral side at last follow-up (104° vs. 131° and 38° vs. 55°, respectively). Non-union was found on X-ray in 4 wrists (18%), but in 2 cases showed as partial non-union on CT, with complete scaphotrapezial consolidation; 1 of the 4 wrists required surgical revision. Another patient was re-operated on for symptomatic external staple displacement without non-union. There were 8 cases (36%) of radiographic narrowing of the styloscaphoid joint space; contact between the staple and styloid was found in all 8 cases. Four patients (18%) had narrowing of the scaphocapital joint space; protrusion of the proximal part of the staple into the joint space was noted in all 4 wrists. No differences were found for the radioscaphoid, capitolunate and scapholunate angles before and after surgery. STT arthrodesis with staple fixation to treat isolated STT OA led to a significant reduction in pain, with improved strength and functional scores. To avoid styloid impingement, we recommend systematic styloidectomy. Complete non-union seems to be overestimated on radiographs. Partial non-union with scaphotrapezial union should not be considered as a complication. LEVEL OF EVIDENCE: IV.