Background Distal spiral fractures of the tibial shaft present fixation challenges, particularly in patients who are not suitable candidates for intramedullary nailing. This study evaluated the biomechanical stability of medial minimally invasive percutaneous plating osteosynthesis (MIPO) under various physiological loading conditions.
Methods A finite-element model of a distal AO/OTA 42-A1.1c spiral fracture of the tibia was created using computed tomography data. A precontoured titanium medial distal tibia locking compression plate with nine locking screws was simulated. Material properties were assigned to cortical and cancellous bone. The loading conditions included axial compression (750 N), varus/valgus bending (300 N at a 9° offset), and internal/external torsion (7.5 N·m). von Mises stress and fracture displacement were analyzed.
Results Axial loading produced a peak plate stress of 508.06 MPa and a displacement of 2.17 mm. Valgus and varus loading generated stresses of 490.17 MPa and 324.08 MPa, respectively, with corresponding displacements of 3.86 mm and 2.01 mm. External and internal torsion resulted in stresses of 354.23 MPa and 358.9 MPa, respectively, with corresponding displacements of 2.64 mm and 2.22 mm.
Conclusions Medial distal tibial plating demonstrated favorable biomechanical performance in this finite-element model; however, clinical extrapolation should be made cautiously.
Level of evidence: V.
Background Patellar fractures are common injuries that require stable fixation to achieve optimal healing and restoration of knee function. This study aimed to analyze the mechanical properties of an anatomically precontoured patellar plate and to compare its maximum tensile load-bearing capacity with that of anterior tension wiring through cannulated screws and double-sided plating for the fixation of patellar fractures.
Methods Artificial Sawbones with a standardized transverse fracture line were used to simulate patellar fractures. Each sawbone was attached to polyester bands, and this fracture model was applied consistently across all test samples. To evaluate mechanical properties of the anatomically precontoured patellar plate (model code 25-ANPA-209) made of ASTM F67 titanium, static tensile strength testing and dynamic tensile strength testing were performed, with seven samples prepared for each test. For comparison of maximum tensile load capacity among the anatomically precontoured patellar plate, anterior tension wiring through cannulated screws, and double-sided plating, five samples were prepared for each fixation group. All specimens were tested using a tension/compression testing machine.
Results In the static tensile strength test, all seven samples exhibited a maximum tensile load capacity above 844 N without any fractures or failure points. The dynamic tensile strength test showed that all seven samples completed 10,000 cycles without deformation or damage to the anatomically precontoured patellar plate. When comparing maximum tensile load capacity, the anatomically precontoured patellar plate exhibited a significantly higher maximum tensile load-bearing capacity than anterior tension wiring through cannulated screws and double-sided plating.
Conclusions The anatomically precontoured patellar plate demonstrated satisfactory mechanical performance, successfully meeting the criteria of both static and dynamic tensile strength testing, and showed superior maximum tensile load-bearing capacity compared with the other fixation methods evaluated. These findings suggest that the anatomically precontoured patellar plate may represent a reliable fixation option for the management of patellar fractures.
Level of evidence: V.
Background Progressive osteoporosis reduces the trabecular structures of the proximal femur, whereas the primary compression trabeculae (PCTs) are relatively preserved. We hypothesize that the loss of the vertically oriented PCTs in osteoporosis, which act as a mechanical barrier, affects fracture line propagation and influences the Pauwels angle. This study investigated the association between bone mineral density (BMD) and Pauwels angles in low-energy femoral neck fractures (FNFs).
Methods This cross-sectional study included 150 patients (mean age, 75.3 years; range, 50–94 years) diagnosed with intracapsular FNFs between May 2019 and May 2023. BMD was measured within 1 month of the injury date using dual-energy X-ray absorptiometry, and modified Pauwels angles were assessed using a computed tomography-based multiplanar reconstruction program. Multiple linear regression analysis was performed to evaluate the factors influencing the Pauwels angles. The dependent variable was the Pauwels angle, while the independent variables included sex, age, height, body weight, body mass index, American Society of Anesthesiologists score, Charlson comorbidity index score, smoking status, alcohol use, preinjury walking ability, and femoral neck BMD T-scores.
Results Higher femoral neck BMD T-scores were significantly associated with increased Pauwels angles (β=3.449, P<0.001). Greater body weight was independently associated with increased Pauwels angles (β=0.213, P=0.007).
Conclusions The Pauwels angle demonstrated a significant association with BMD, with lower BMD associated with less steep Pauwels angles. In the absence of BMD measurement, the Pauwels angle may indicate osteoporosis severity in patients with low-energy FNFs.
Level of evidence: III.