Biomechanical comparison of screw and minimally invasive locking plate fixation for calcaneal fracture stabilization: a finite element analysis and clinical study

The optimal strategy for managing fixation failure in joint depression calcaneal fractures, particularly in Sander’s type-II and type-III cases, remains uncertain. The minimally invasive sinus tarsi (STA) approach has been increasingly adopted due to its reduced risk of soft tissue complications. Although the STA effectively reduces soft-tissue disruption, the biomechanical superiority of different fixation constructs remains uncertain. This study aimed to compare the biomechanical stability and clinical outcomes of three fixation techniques: screw fixation (SF), two-point without tuberosity, and two-point with tuberosity. FE analysis was performed to simulate Sander’s type-II and type-III fractures, evaluating implant stress distribution and elastic strain at the fracture site in different fixation constructs. Moreover, FE models were reconstructed from CT images and validated through 3D-printed mechanical compression testing under an axial load of 300 N, yielding an average deviation of less than 10% between experimental and simulated strains. Additionally, a retrospective clinical review included 72 patients whose postoperative outcomes were assessed using radiographic restoration and the Foot and Ankle Ability Measure. The two-point tuberosity fixation exhibited the lowest strain at the fracture site and the most favorable stress distribution, confirming its superior construct stability. This fixation achieved better maintenance of anatomical alignment and significantly higher FAAM scores (92.2 ± 6.0 vs. 78.8 ± 15.3, p < 0.001) compared with SF. These findings suggest integrating FE for biomechanics with a clinical study. The study demonstrates that two-point fixation incorporating tuberosity support provides enhanced stability and improved functional recovery, supporting its recommendation as an optimal minimally invasive strategy for Sander’s type II and III calcaneal fractures. These results were consistent between FEA and clinical outcomes. • No consensus exists for fixation in Sander’s type II–III calcaneal fractures. • Two-point LCP with tuberosity gives the lowest strain and the highest stability. • LCP fixation preserved Bohler’s angle and improved FAAM vs screw fixation. • LCP with tuberosity stabilization is the recommended minimally invasive option.