Parallel versus Angulated Screw Configuration in Subtalar Arthrodesis for Posttraumatic Arthritis.

Background: To compare radiographic union and clinical outcomes between parallel and angulated screw configurations (SCs) for patients undergoing subtalar arthrodesis due to posttraumatic subtalar arthritis (PSA) after displaced intra-articular calcaneal fractures.

Methods: This study retrospectively reviewed 140 consecutive PSA cases from March 2011 to November 2021 (parallel SC: group 1, n = 80; angulated SC: group 2, n = 60). Radiographic union, Foot and Ankle Outcome Score (FAOS), and visual analog scale (VAS) scores were among the outcome assessments. Six months after surgery, nonunion was confirmed based on plain radiographs, clinical evaluation, and computed tomography.

Results: Groups 1 and 2 included 14 (17.5%) and 3 (5.0%) nonunion cases, respectively (p = 0.035). There was no significant difference in preoperative FAOS and VAS scores between the groups. However, group 2 had significantly better clinical outcomes in 2 of the 5 FAOS domains (sports and quality of life), as well as VAS scores at 3 and 6 months postoperatively and at the final follow-up (p < 0.05).

Conclusions: Using the angulated SC for PSA had a lower nonunion rate and superior clinical outcomes than the parallel SC. Obtaining better radiological and clinical outcomes when using the angulated SC, rather than the parallel SC, would be advantageous.