Does Soong grade predict radiological and functional outcomes after distal radius fracture plating?

Distal radius fractures (DRFs) are frequently managed with volar locking plates (VLP). The Soong classification, which grades plate prominence relative to the volar rim, is widely used because of its association with flexor tendon irritation, but its value in predicting postoperative radiographic restoration and patient-reported outcomes is less clear. This study examined whether Soong grade correlates with alignment (radial height and radial inclination) and patient-rated outcomes after VLP fixation of DRFs.

We conducted a retrospective review of consecutive patients undergoing surgical fixation for DRF, 44 met the inclusion criteria. Demographics, fracture characteristics, operator grade, time from injury to operation, radiation dose, postoperative imaging and clinic utilisation, antibiotic use, and a patient-rated outcome score were collected. Pre- and postoperative anteroposterior radiographs were used to measure radial height and radial inclination. Plate prominence was graded as Soong 0-2.

The cohort was predominantly female (72.7%) with a mean age of 53.5 years (range 23-82, SD 16.3). Most fractures were intra-articular (88.6%) and dorsally angulated (79.5%). Mean time from injury to operation was 9.8 days (SD 5.8). Patient-rated outcome scores typically ranged 60-80 and did not appear to vary by sex, operator grade, or fracture configuration. By Soong grade, Grade 0 (n = 23) demonstrated the most favourable radiological restoration with mean postoperative radial height 13.6 mm and inclination 26.4°, alongside the highest mean patient-rated outcome score of 74.1. Grade 1 (n = 14) showed slightly lower restoration (radial height 12.1 mm, inclination 26.4°) and a mean outcome score of 65.3 with wider variability. Grade 2 (n = 7) had the least favourable radiology (radial height 11.7 mm, inclination 24.3°) and the lowest mean outcome score of 61.5; one patient in this group underwent plate removal for flexor tendon irritation.

In this single-centre retrospective series of VLP fixation for DRF, lower Soong grade-particularly Grade 0-was associated with better restoration of radial height and inclination and higher patient-rated outcome scores, whereas higher grades demonstrated a stepwise reduction in radiographic and functional results. These findings support meticulous plate positioning to minimise volar rim prominence and justify prospective, adequately powered studies to confirm the observed trends and evaluate longer-term tendon-related complications.