Radial styloidectomy for scaphoid nonunion advanced collapse (SNAC) – relevance of nonunion location.
Emil Stefan Vutescu, MD1; Darryl B Sneag, MD2; Scott W Wolfe, MD3; Steve K Lee, MD2; (1)Brown University, Providence, RI, (2)Hospital for Special Surgery, New York, NY, (3)Hand and Upper Extremity Service, Hospital for Special Surgery, New York, NY
Radial styloidectomy with scaphoid nonunion surgery is considered an acceptable surgical treatment for stage 1 scaphoid nonunion advanced collapse (SNAC). Traditional SNAC radiographic classification has poor inter- and intra-observer reliability and the extent of radioscaphoid joint wear that defines SNAC stage 1 is unclear.
An appropriate radial styloidectomy is limited to 4 mm styloid removal in order to prevent carpal instability. The aim of this study is to determine if nonunion fracture location can be a guiding factor in choosing radial styloidectomy as a surgical option for early SNAC. We hypothesized that radial styloidectomy is not appropriate for proximal third scaphoid nonunions.
Patients ages ³18 who had wrist radiographs and MRI at our institution from 2007-2014 with a diagnosis of SNAC stage 1 were included in this retrospective study. Wrist MRI studies were interpreted by a musculoskeletal MRI radiologist. Fracture location was documented as the proximal, middle or distal third. The radioscaphoid joint was assessed using coronal and sagittal cartilage-sensitive fast spin echo sequences. Chondral wear (defined as > 50% cartilage thickness loss) was quantified as the length of a horizontal line (mm) traced from the tip of the radial styloid to the most ulnar position along the radioscaphoid joint where no more wear could be identified (Figure 1). Patients were divided into 2 categories: chondral wear of < 4 mm and wear of ³ 4 mm. Association between fracture location and wear was assessed using the FischerÕs Exact Test.
Twenty-one patients (19 men) with SNAC stage I met the inclusion criteria. The mean age was 37 years (range 18-71). Average time between MRI and date of injury was 80 months (range 11- 372). Fracture location was as follows: 10 proximal third, 8 middle third and 3 distal third. Patients with < 4 mm of joint wear were more likely to have the scaphoid fracture localized in the middle and distal thirds (100%) compared to those with proximal third nonunions (9%) (p<0.0001).
Our results demonstrate that radial styloidectomy with scaphoid nonunion surgery is appropriate for nonunions located in the distal or middle third of the scaphoid. The majority of our patients with proximal third nonunions showed radioscaphoid joint wear that exceeded the 4 mm limit for a safe styloidectomy.
Figure 1 – Measurement of radioscaphoid joint wear for a proximal third scaphoid nonunion.
Back to 2018 Program