Functional and Radiological Outcomes of Calcar Buttress Biplane Double-Supported Screw Fixation (BDSF) Using a Locking Compression Screw System for Intracapsular Femoral Neck Fractures: A Prospective Observational Study.

Background Intracapsular femoral neck fractures in adults aged 40-60 years present a therapeutic challenge. Calcar buttress fixation using the biplane double-supported screw fixation (BDSF) concept serves to enhance load transfer through dual cortical support. This study aimed to evaluate the functional and radiological outcomes of calcar buttress BDSF fixation using a locking compression screw system in adults aged 40-60 years with intracapsular femoral neck fractures. Methods This prospective observational study was conducted at a tertiary care hospital from September 2022 to June 2024 and included adults aged 40-60 years with intracapsular femoral neck fractures presenting within three weeks of injury. All 25 patients underwent closed reduction and internal fixation using calcar buttress BDSF with a titanium locking compression screw system. Standardized rehabilitation included progressive weight-bearing from toe-touch at one week to full weight-bearing by 8-12 weeks. Patients were assessed at 1, 3, 6, and 12 months using the Harris Hip Score (HHS) and Visual Analogue Scale (VAS). Radiological union, Pauwels type-wise outcomes, and complications were recorded. Serial functional outcomes were compared using paired t-tests, and subgroup categorical comparisons were analyzed using Fisher's exact test, as appropriate. Results Mean age was 50.6 years (range 40-60 years); 16 of 25 patients (64.0%) were male. Falls accounted for 16 of 25 injuries (64.0%). Mean operative time was 58.8 minutes, with a mean intraoperative blood loss of 44 mL. Mean HHS improved significantly from 72.72 ± 7.22 at one month to 87.84 ± 7.30 at 12 months (p < 0.001). At 12 months, 14 of 25 patients (56.0%) achieved excellent outcomes, 7 of 25 (28.0%) achieved good outcomes, and 4 of 25 (16.0%) achieved fair outcomes; none had poor results. Mean VAS decreased from 8.04 ± 0.74 to 2.68 ± 1.38 (p < 0.001). Overall radiological union at 12 months was achieved in 24 of 25 patients (96.0%; 95% CI: 80.5%-99.3%). Union rates by Pauwels type were as follows: type 1, 4/4 (100.0%; 95% CI: 51.0%-100.0%); type 2, 11/12 (91.7%; 95% CI: 64.6%-98.5%); and type 3, 9/9 (100.0%; 95% CI: 70.1%-100.0%). Mean femoral neck shortening at 12 months was 5.3 ± 1.4 mm overall and was greatest in Pauwels type 3 fractures (6.5 ± 1.0 mm; p < 0.001). Conclusions Calcar-buttress BDSF fixation using a locking compression screw system may be considered a head-preserving fixation technique with encouraging early results for intracapsular femoral neck fractures in adults aged 40-60 years; however, the modest sample size and wide subgroup confidence intervals require cautious interpretation and preclude definitive comparative conclusions. Larger comparative studies are needed to confirm these findings.