Ulnar styloid osteolysis following distal radius fracture without ulnar fracture: frequency and associated factors

OBJECTIVES: To determine the frequency and characteristics of ulnar styloid osteolysis after distal radius fracture without concomitant ulnar fracture. Secondary objectives were to assess associated risk factors and surgical outcomes. MATERIALS AND METHODS: A retrospective observational, single-center, radiographic cohort of adult patients diagnosed with distal radius fracture between July 1, 2018, and June 30, 2020, was reviewed. Ulnar styloid osteolysis was documented using wrist radiographs at diagnosis and follow-up. Patients with ulnar fractures or erosive arthropathy were excluded. Time to detection, size, morphology, location, and evolution of ulnar styloid osteolysis were recorded. Associations with patient and fracture characteristics were evaluated using Cox models. RESULTS: 143 patients (104 female, mean age 55.8 ± 17.6 years) were included. Ulnar styloid osteolysis was identified in 16.8% of patients (n = 24), with a median detection time of 56 days (range 24-386). Osteolysis was more likely in fractures with: comminution (83.3% vs. 59.7%, HR = 3.457 [1.145-9.845], p = 0.027), diastasis (33.3% vs. 10.1%, HR = 3.905 [1.646-9.266], p = 0.002), dorsal angulation (79.2% vs. 24.4%, HR 4.766 [1.619-14.035], p < 0.001), impaction (66.7% vs. 17.6%, HR = 5.823 [2.486-15.647], p < 0.001) and active smoking (35.5% vs. 16.5%, HR = 2.650 [1.054-6.665], p = 0.038). Osteolysis was more frequently observed in patients who underwent surgery (50.0% vs. 20.2%, HR 2.541 [1.119-5.770], p = 0.026). No significant association with age, sex, osteoporosis, scapholunate dissociation, step-off deformity, or intra-articular extension. CONCLUSION: Ulnar styloid osteolysis was observed in approximately one in six patients with distal radius fractures in this cohort; this finding was associated with multiple markers of fracture severity. KEY POINTS: Question How often does ulnar styloid osteolysis occur after a distal radius fracture without ulnar involvement, and what clinical factors are associated with its development? Findings Ulnar styloid osteolysis develops in up to 16.8% of patients with radial fractures not associated with ulnar fracture in our population. Clinical relevance Ulnar styloid osteolysis after radial fracture occurs more frequently in patients with greater fracture comminution, dorsal angulation, diastasis, and impaction, as well as smokers. It must be differentiated from inflammatory arthropathies to avoid unnecessary investigations.