Search Results (6)

Background/Objectives: Avulsion fractures of the fifth metatarsal often require surgical fixation when displacement or instability is present. This study aimed to compare the biomechanical performance of hook-plate and bicortical screw fixation using anatomically accurate 3D-printed metatarsal models analyzed through digital image correlation (DIC). Methods: Multi-material 3D-printed specimens were subjected to simulated gait-phase loading (α = 0°, 90°, 180°), combined with three interfragmentary distances (d = 0.1, 0.5, 1 mm) following a replicated 3 × 3 factorial design (n = 27 per fixation method). Full-field strain and displacement maps were quantified using ARAMIS DIC. Results: Hook-plate fixation consistently produced lower maximum stresses compared with bicortical screws (reductions of 9–36 MPa across conditions). The highest stresses were observed for screw fixation at α = 90° and d = 0.1 mm (100.3 ± 1.5 MPa), while the lowest occurred for hook plates at α = 180° and d = 1 mm (33.3 ± 1.5 MPa). ANOVA confirmed significant α×d interactions (p < 0.01). Conclusions: Hook-plate fixation provided superior angular stability and suggested improved cyclic performance compared to bicortical screws, favoring early mobilization. The combined use of 3D printing and DIC represents a valuable framework for preclinical implant evaluation. These results provide useful insights for selecting the optimal fixation technique in clinical management of fifth metatarsal avulsion fractures. Full article

Background/Objectives: Proximal interphalangeal joint (PIJ) arthrodesis is a common surgical intervention for patients with PIJ osteoarthritis or trauma-related joint destruction. The objective of this study was to evaluate the biomechanical stability of various arthrodesis techniques under forces comparable to activities of daily living (ADL) to assess their suitability for early active movement protocols. Methods: In this in vitro study, composite cylinders simulating PIJ arthrodesis were subjected to standardized fusion angles of 40° using different fixation techniques, including crossed K-wires, compression screws, cerclage wires, tension band wiring, anatomical fixation plates, and locking grid plates. Forces representing ADLs such as typing, holding a pencil, carrying weight, and opening a jar were applied using a universal testing machine in a four-point bending setup. Micromotion and gap clearance were calculated and analyzed. Results: Techniques involving compression, such as compression screws, tension bands, and cerclage wires, exhibited lower micromotion and gap clearance under forces up to 17 N, suggesting potential suitability for early active movement protocols. In contrast, fixation plates demonstrated structural failure or excessive clearance during early active motion ADLs. K-wires showed intermediate results with moderate gap clearance and micromotion. Conclusions: Compression-based fixation techniques for PIJ arthrodesis may permit early active movement without external stabilization, while fixation plates are prone to failure under ADL forces. Further dynamic biomechanical testing and clinical studies are recommended to confirm these findings. Full article

The surgical stabilization of rib fractures helps maintain chest wall stability and reduces respiratory complications. This study aimed to identify the key biomechanical parameters for evaluating the stability of rib fracture fixation using finite element analysis (FEA) and compare four rib fixation configurations—intramedullary rib splint (IRS), locking plate (LP), claw-shape plate, and intrathoracic plate (IP)—using biomechanical analysis. Forty patient-specific FEA models of fourth-rib fractures were constructed using the computed tomography scans of 10 patients. Maximum implant displacement (MID), maximum rib fracture displacement, maximum implant von Mises stress (MIVMS), maximum rib von Mises stress, maximum rib strain, and maximum interfragmentary gap (MIG) were assessed by simulating the anterior and posterior loads on the ribs during postoperative frontal collision. The fixation stabilities were evaluated using entropy scores. MIVMS, MIG, and MID exhibited the highest weighting coefficients. Lateral cortical fixation strategies, particularly LP configuration, demonstrated superior biomechanical performance compared with IRS and IP systems. The composite score of the LP was significantly higher than that of the other modalities. MIVMS, MIG, and MID were identified as critical parameters for evaluating the rib fracture fixation stability, and the lateral cortical fixation strategy (LP) enhanced the structural stability of rib fracture fixation. Full article

(1) Background: Bone healing is influenced by various mechanical factors, such as stability, interfragmentary motion, strain rate, and direction of loading. Far cortical locking (FCL) is a novel screw design that promotes bone healing through controlled fracture motion. (2) Methods: This study compared the outcome of distal femur fractures treated with FCL or SL (standard locking) screws and an NCB plate in a randomised controlled prospective multicentre trial. The radiographic union scale (RUST) and healing time was used to quantify bone healing on follow-up imaging. (3) Results: The study included 21 patients with distal femur fractures, 7 treated with SL and 14 treated with FCL screws. The mean working length for patients with SL screws was 6.1, whereas for FCL screws, it was 3.9. The mean RUST score at 6 months post fracture was 8.0 for patients with SL plates and 7.3 for patients with FCL plates (p value > 0.05). The mean healing time was 6.5 months for patients with SL plates and 9.9 months for patients with FCL plates (p value < 0.05). (4) Conclusions: Fractures fixed with SL plates had longer working lengths and faster healing times when compared to FCL constructs, suggesting that an adequate working length is important for fracture healing regardless of screw choice. Full article

An understanding of the biomechanical characteristics and configuration of flexible and locked plating in order to provide balance stability and flexibility of implant fixation will help to construct and promote fast bone healing. The relationship between applied loading and implantation configuration for best bone healing is still under debate. This study aims to investigate the relationship between implant strength, working length, and interfragmentary strain (εIFM) on implant stability for femoral midshaft transverse fractures. The transverse fracture was fixed with a fragment locking compression plate (LCP) system. Finite element analysis was performed and subsequently characterised based on compression loading (600 N up to 900 N) and screw designs (conventional and locking) with different penetration depths (unicortical and bicortical). Strain theory was used to evaluate the stability of the model. The correlation of screw configuration with screw type shows a unicortical depth for both types (p < 0.01) for 700 N and 800 N loads and (p < 0.05) for configurations 134 and 124. Interfragmentary strain affected only the 600 N load (p < 0.01) for the bicortical conventional type (group BC), and the screw configurations that were influenced were 1234 and 123 (p < 0.05). The low steepness of the slope indicates the least εIFM for the corresponding biomechanical characteristic in good-quality stability. A strain value of ≤2% promotes callus formation and is classified as absolute stability, which is the minimum required value for the induction of callus and the maximum value that allows bony bridging. The outcomes have provided the correlation of screw configuration in femoral midshaft transverse fracture implantation which is important to promote essential primary stability. Full article

Proximal humerus fractures increase with the aging of the population. Due to the high failure rates of surgical treatments such as open reduction and internal fixation (ORIF), biomechanical studies seek to optimize the treatments and intervening factors to improve the quality of life of people undergoing these treatments. The aim of the present study was to determine the optimal insertion angle configuration of screws used in a two-part proximal humerus fracture-locking plate osteosynthesis treatment based on finite element analysis (FEA). A series of 3D models of PHILOS locking plates with different screw insertion angle configurations were designed using a matrix system for screw angulation. The locking plate models were evaluated in a two-part proximal humerus fracture with surgical neck fracture under bending and compressive loading conditions using FEA and statistically analyzed using a design of experiments (DOE). The optimal screw insertion angle setting showed an improvement in relation to the interfragmentary strain value of the fracture. Moreover, calcar screws were the most significant feature in fracture stability throughout the tests, followed by the divergence of the most proximal screws and the proximal–distal alignment of the locking plate. Full article