Clinical and radiological outcomes of displaced intra-articular calcaneal fractures treated through the sinus tarsi approach: a prospective study

Background: Displaced intra-articular calcaneal fractures (DIACFs) remain technically demanding because satisfactory articular reduction must be achieved without adding further injury to an already vulnerable soft-tissue envelope. The sinus tarsi approach (STA) offers a limited route to the posterior facet. This prospective study evaluated clinical and radiological outcomes after fixation of DIACFs through the STA. Methods: Twenty adults with closed Sanders type II-IV DIACFs were enrolled prospectively at a Kasturba Medical College, Mangalore, Karnataka, tertiary care teaching hospital between January 2023 and December 2024. All fractures were treated through the STA, with the definitive fixation construct chosen according to fracture morphology and intraoperative stability. Radiological assessment included preoperative-to-postoperative change in Böhler's and Gissane's angles and time to union. Functional recovery was assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score at 6, 12, and 24 weeks and at 1 year. Complications were recorded throughout follow-up. Results: All 20 patients completed 1-year follow-up. Mean age was 34.80±10.68 years, and 16 injuries (80.0%) followed a fall from height. Sanders type III fractures were most frequent (10/20, 50.0%), followed by type IV (7/20, 35.0%) and type II (3/20, 15.0%). Mean change in Böhler's angle was 15.30±5.67° and mean change in Gissane's angle was 20.15±9.56°. Radiological union occurred at a mean of 10.75±1.45 weeks. Mean AOFAS score was 53.30±12.16 at 6 weeks and 86.35±5.87 at 1 year. At final follow-up, 19 patients (95.0%) had a good or excellent AOFAS outcome. Four patients (20.0%) experienced postoperative complications: superficial wound infection in two patients (10.0%), ankle fibrosis in one patient (5.0%), and ankle fibrosis with varus deformity in one patient (5.0%). No deep infection or non-union was documented. Conclusions: Fixation of DIACFs through the STA was associated with radiographic correction, progressive postoperative functional recovery, and fracture union in this prospective series. These findings support the STA as a practical operative corridor for appropriately selected DIACFs, while the inclusion of Sanders type IV fractures warrants cautious interpretation and longer-term evaluation.