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Evaluating the Impact of Sigmoid Notch Morphology on Outcomes Following Ulnar Shortening Osteotomy
John Mwangi, BS
1, Joshua K. Kim, BS
1, Ryon Yu, BS
1, Hani I Naga, MD
2; Warren C. Hammert, MD
3(1)Duke University School of Medicine, Durham, NC, (2)Duke University Medical Center, Durham, NC, (3)Duke University, Durham, NC
Background: Ulnar impaction syndrome is a common cause of ulnar-sided wrist pain in patients with positive ulnar variance. Ulnar shortening osteotomy (USO) reduces ulnocarpal load but alters the distal radioulnar joint (DRUJ), but some have concerns in patients with reverse oblique or Type III sigmoid notch morphologies. Prior studies have suggested the altered contact forces may result in DRUJ arthritis; however, long-term outcomes and patient-reported outcomes (PROs) across different notch are unclear. This study aimed to quantify radiographic DRUJ arthritis and assess functional outcomes after USO based on sigmoid notch morphology, comparing Type III to Types I and II.
Materials & Methods: A retrospective chart review was conducted on 1,000 patients undergoing USO at a single tertiary care center between 2010 and 2024. Patients were categorized by sigmoid notch morphology (Type I [ n = 77], II [n =27], III [ n = 26]) and excluded if they had prior operations on ipsilateral wrist. Demographics, preoperative characteristics, radiographic measurements, surgical details, and postoperative complications were recorded. Outcomes included radiographic DRUJ arthritis, wrist motion, grip strength, and PROMIS and QuickDASH scores at multiple time points. Comparative analysis was performed to assess differences among notch types.
Results: PROMIS scores for pain interference, physical function, and upper extremity function showed no significant differences across groups at any postoperative interval (all p>0.1). Type III morphology was associated with greater preoperative ulnar variance (median 4.1 mm vs 3 mm, p=0.037) and increased ulnar shortening performed during surgery (median 5 mm vs 4.5 mm, p=0.039). While the overall rates of radiographic DRUJ arthritis did not significantly differ among the three groups (p=0.607), Type III patients demonstrated prolonged orthopedic follow-up (median 875 days vs 351 days for Type I, p=0.007). Complication and reoperation rates were low and comparable between groups. Functional outcomes, including grip strength and range of motion, were also similar across sigmoid notch types.
Conclusion: Although patients with Type III sigmoid notch morphology underwent greater ulnar shortening and had longer follow-up, rates of radiographic DRUJ arthritis and patient-reported outcomes were not significantly worse compared to Types I and II. These findings challenge the notion that reverse oblique DRUJ inclination adversely impacts outcomes after USO. Patient-reported outcomes, rather than radiographic changes alone, may be more relevant for guiding postoperative management.
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