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Ulnar Shortening Osteotomy: Is it Necessary to Create Ulnar Neutral Variance?
Loukia K. Papatheodorou, MD; Joel V. Ferreira, MD; Mark E. Baratz, MD; Dean G. Sotereanos, MD University of Pittsburgh, Pittsburgh, PA
Introduction
Ulnar shortening osteotomy (USO) is commonly performed for surgical treatment of ulnar impaction syndrome. Although the recommended amount of ulnar shortening varies in the literature, most studies advocate between neutral and 2 mm of negative ulnar variance. However, with increasing amounts of shortening, biomechanical and long-term clinical studies have shown an increased risk of developing distal radioulnar joint (DRUJ) arthritis. The purpose of the study was to determine if a limited step-cut USO of 2-3 mm would provide symptom resolution in the treatment of ulnar impaction syndrome regardless of pre-operative ulnar variance. Materials and Methods
We retrospectively reviewed 164 consecutive patients who treated with a limited step-cut USO for ulnar impaction syndrome between 2000-2010. Eighty-eight patients were female and seventy-six were male with a mean age of 36.8 years. Idiopathic ulnar impaction syndrome was diagnosed in 116 patients, while a post-traumatic etiology was seen in the remaining 48 patients. In all cases a limited step-cut USO of 2-3 mm was performed. Ulnar variance was assessed radiographically pre- and post-operatively with the pronated grip view. The mean pre-operative ulnar variance was +3.5 mm (range, +1 mm to +6 mm). Wrist radiographs were assessed post-operatively for evidence of degenerative changes or osteophyte formation at the DRUJ at final follow-up. Results
The mean follow-up was 62.4 months. Union of the osteotomy was achieved with a mean time of 8.2 weeks (range, 5-18 weeks) and at a rate of 98.78% (162/164 cases). There were two cases of nonunion which both went on to heal with revision surgery utilizing autologous iliac crest bone graft. The mean post-operative ulnar variance was +0.2 mm (range, -1 mm to +1.5 mm). In all patients, pain, range of motion, grip strength and Modified Mayo Wrist Score significantly improved postoperatively regardless of the postoperative ulnar variance (negative, neutral, positive). Hardware removal was performed in twelve patients due to persistent plate-related symptoms (7.3%). At final follow-up, asymptomatic degenerative changes at the DRUJ occurred in nine of the 164 patients (5.5%). Conclusions
A limited step-cut USO of 2-3 mm provides excellent union rates and good to excellent functional results, regardless of pre-operative ulnar variance. Limiting the amount of shortening to 2-3 mm results in lower rates of degenerative changes seen at the DRUJ compared to previous literature. The limited ulnar shortening minimizes the rate of DRUJ articular incongruity and diminishes development of DRUJ arthritis.
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