Long-term patient-reported outcomes after nonoperative treatment of distal radial fractures: what CT-based gaps and step-offs can be accepted?

Nonoperative treatment of distal radial fractures is recommended for intra-articular gaps or step-offs under 2 mm; a threshold based on 40-year-old radiographic data, which is still referred to despite the transition toward Computer Tomography (CT)-imaging for assessing displacement. Controversy about treatment exists when displacement slightly exceeds 2 mm. We assessed the association between CT-based gaps and step-offs and patient-reported outcomes after nonoperative treatment, and established CT-based thresholds for fracture displacement. A multicenter retrospective cohort study was performed in 176 nonoperatively treated patients with intra-articular distal radial fractures. They completed Disability of Arm, Shoulder, and Hand (DASH) questionnaire after a mean follow-up of 10 ± 4years. The association between CT-based gap and step-off and DASH was analyzed with multivariate regression analysis, where ‘β’ represents the regression coefficient indicating the estimated change in DASH score per millimeter increase in gap or step-off. Groups with increasing displacement were created (1.Gap and step-off < 2 mm, 2.Gap = 2–4 mm and step-off < 2 mm, 3.Gap < 2 mm, step-off = 2–4 mm, 4.Gap and step-off = 2–4 mm and 5.Gap or step-off > 4 mm), and DASH-scores were compared using Mann-Whitney-U tests. There was no association between DASH and gap (β = 0.66 p = 0.414) or step-off (β = 1.73; p = 0.061). The difference in DASH-score between groups 1 (gap and step-off < 2 mm) and group 2 (gap = 2–4 mm and step-off < 2 mm) was not clinically relevant (4 ± 7 vs. 7 ± 11; p = 0.010). Groups 3,4,5, with step-offs > 2 mm were too small for comparisons, as larger step-offs were rarely accepted clinically. We found no association between the CT-based gaps and step-offs and DASH in patients with nonoperatively treated distal radial fractures with intra-articular displacement around and even slightly above 2 mm. Gaps up to 4 mm and step-offs up to 2 mm are associated with good patient-reported outcomes. Level III, prognostic study.