The Influence of Sigmoid Notch Involvement on Radiologic and Clinical Outcome in C2/3 Distal Radius Fractures.

Sigmoid notch involvement is one of the common fracture patterns in C2/3 distal radius fractures. Since the sigmoid notch and distal ulna and constitutes the distal radioulnar joint (DRUJ), involvement of the sigmoid notch often predicts a poor prognosis. However, following surgical intervention with a volar plate, we can adequately address sigmoid notch fractures and anticipate favorable outcomes. The correlation between the clinical outcomes and the Sigmoid notch involvement has not been thoroughly investigated. Therefore, the purpose of this study was to analyze and evaluate the clinical results and the prevalence of DRUJ arthritis and after volar plating in patients with sigmoid notch involvement in distal radius fracture.

We conducted retrospective review who underwent surgical treatment for C2/3 type distal radius fractures. Patients without sigmoid notch involvement were categorized into Group A, while those with involvement were assigned to Group B. Clinical outcomes after surgery were assessed in each group using the Visual Analog Scale (VAS) pain score, wrist range of motion, Disabilities of the Arm, Shoulder, and Hand (DASH) score, and Modified Mayo Wrist Score (MMWS). The occurrence of DRUJ arthritis and other complication was also examined. For radiographic parameter, we measured intra articular gap distance and step-off, as well as the sigmoid notch axial gap and step-off and degree of DRUJ subluxation at the time of injury through pre-operative CT scans and re-measured these parameters on the final follow-up CT.

A total of 72 patients were included in Group A, and 115 in Group B. Pain and range of motion showed no significant differences between Group A and Group B. However, statistically significant difference in DASH (10.4 vs. 19.7) and MMWS (86.3 vs. 79.3) scores, with superior result in Group A (p<0.001). Subgroup analysis investigating the presence of ulna fractures also revealed that the statistical difference is more pronounced when an ulna fracture is co-existed. DRUJ arthritis occurred in 1 case in Group A and 2 cases in Group B, showing no significant difference in incidence rates (1.4% vs 1.7%). Sigmoid notch axial gap distance, step-off, and the degree of DRUJ subluxation in both Group improved after surgery compared to preoperative measurements.

Distal radius fractures involving the sigmoid notch did not exhibit a higher prevalence of post-traumatic DRUJ arthritis in patients treated with volar plate surgery. Although fractures involving the sigmoid notch showed statistically inferior results, achieving clinically and radiologically favorable outcomes through volar plating.

Keywords: Distal radius fractures, Sigmoid notch, DRUJ, Arthritis, Volar plate, Surgical Outcome