Background and Objectives: The surgical treatment of proximal humeral shaft fractures usually considers application of either long straight plates or intramedullary nails. By being able to spare the rotator cuff and avoid the radial nerve distally, the implementation of helical plates might overcome the downsides of common fixation methods. The aims of the current study were (1) to explore the biomechanical competence of different plate designs and (2) to compare their performance versus the alternative treatment option of using intramedullary nails. Materials and Methods: Twenty-four artificial humeri were assigned to the following four groups for simulation of an unstable proximal humeral shaft fracture and instrumentation: Group 1 (Straight-PHILOS), Group 2 (MULTILOC-Nail), Group 3 (45°-Helical-PHILOS), and Group 4 (90°-Helical-PHILOS). All specimens underwent non-destructive, quasi-static biomechanical testing under loading in axial compression, torsion in internal/external rotation, and pure bending in four directions, accompanied by motion tracking. Results: Axial stiffness/displacement in Group 2 was significantly higher/smaller than in all other groups (p ≤ 0.010). Torsional displacement in Group 2 was significantly bigger than in all other groups (p ≤ 0.017). Significantly smaller coronal plane displacement was identified in Group 2 versus all other groups (p < 0.001) and in Group 4 versus Group 1 (p = 0.022). Significantly bigger sagittal plane displacement was detected in Group 4 versus all other groups (p ≤ 0.024) and in Group 1 versus Group 2 (p < 0.001). Conclusions: Intramedullary nails demonstrated higher axial stiffness and smaller axial interfragmentary movements compared with all investigated plate designs. However, they were associated with bigger torsional movements at the fracture site. Although 90°-helical plates revealed bigger interfragmentary movements in the sagittal plane, they demonstrated improved resistance against displacements in the coronal plane when compared with straight lateral plates. In addition, 45°-helical plates manifested similar biomechanical competence to straight plates and may be considered a valid alternative to the latter from a biomechanical standpoint.

This study presents a preliminary characterization of selective plated antibacterial copper coatings on medical-grade stainless steel 1.4021 and nickel alloy Ni200 substrates using two different copper electrolyte solutions with acidic and alkaline pH. The characterizations included analysis of the microstructure, phase composition, surface roughness, and antibacterial activity against Gram-positive Staphylococcus aureus ATCC 29213 and Gram-negative Escherichia coli ATCC 25922 bacteria. The results revealed uniform and continuous layers of single-phase solid-solution copper coatings without any cracks or defects. The coatings, produced using acidic or alkaline solutions, exhibited approximately 20% or 40% lower surface roughness compared to the substrate roughness. This suggests that the plating process led to a smoother surface finish. Importantly, all of the selective plated copper coatings exhibited antibacterial properties. Inhibition zones were identified, indicating the ability of the coatings to inhibit the growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The use of the alkaline copper solution resulted in slightly larger inhibition zones compared to the acidic solution, indicating enhanced antibacterial activity. These findings suggest that the selective plated copper coatings on medical-grade stainless steel 1.4021 and nickel alloy Ni200 substrates have the potential to be effective antibacterial surfaces.

Background and Objectives: Minimally invasive surgeries for acetabulum fracture fixation are gaining popularity due to their known advantages versus open reduction and internal fixation. Antegrade or retrograde screw fixation along the long axis of the posterior column of the acetabulum is increasingly applied in surgical practice. While there is sufficient justification in the literature for the application of the anterior approach, there is a deficit of reports related to the posterior approach. The aim of this study was to evaluate the biomechanical competence of posterior column acetabulum fracture fixation through antegrade screw placement using either a standard cannulated screw or a cannulated compression headless screw (CCHS) via posterior approach. Materials and Methods: Eight composite pelvises were used, and a posterior column acetabulum fracture according to the Letournel Classification was simulated on both their left and right sides via an osteotomy. The sixteen hemi-pelvic specimens were assigned to two groups (n = 8) for either posterior column standard screw (group PCSS) or posterior column CCHS (group PCCH) fixation. Biomechanical testing was performed by applying steadily increased cyclic load until failure. Interfragmentary movements were investigated by means of motion tracking. Results: Initial stiffness demonstrated significantly higher values in PCCH (163.1 ± 14.9 N/mm) versus PCSS (133.1 ± 27.5 N/mm), p = 0.024. Similarly, cycles and load at failure were significantly higher in PCCH (7176.7 ± 2057.0 and 917.7 ± 205.7 N) versus PCSS (3661.8 ± 1664.5 and 566.2 ± 166.5 N), p = 0.002. Conclusion: From a biomechanical perspective, CCHS fixation demonstrates superior stability and could be a valuable alternative option to the standard cannulated screw fixation of posterior column acetabulum fractures, thus increasing the confidence in postoperative full weight bearing for both the patient and treating surgeon. Whether uneventful immediate postoperative full weight bearing can be achieved with CCHS fixation should primarily be investigated in further human cadaveric studies with a larger sample size.

Introduction: Current literature lacks recommendations regarding proper fixation of comminuted coronal plane fractures of the posterior femoral condyles (Hoffa fractures). Therefore, the aim of this study was to compare the biomechanical characteristics of different plate-augmented constructs to isolated posteroanterior screw fixation in comminuted lateral Hoffa fractures. Materials and methods: Comminuted Letenneur type IIb lateral Hoffa fractures were simulated in 24 human cadaveric distal femora. The fractures were fixed with either isolated crossed posteroanterior screws or additionally with either a posterior plate, a lateral locking plate, or combined posterior and lateral locking plates. All specimens were biomechanically tested under progressively increasing cyclic loading until failure, while capturing the interfragmentary movements of the Hoffa and intercalary fragments via motion tracking. Results: Plate-augmented posteroanterior screw fixation of the Hoffa fragment exhibited higher cycles to failure, higher failure loads ( p < 0.05) and less axial displacements ( p < 0.05) compared to isolated posteroanterior screw fixation. Both additional lateral locking and double plate fixations of the intercalary fragment provided higher cycles to failure, higher failure loads ( p < 0.05) and less axial displacement ( p < 0.05) than isolated posteroanterior screw fixation, whereas additional posterior plate fixation did not significantly increase cycles to failure, failure loads and axial displacement (n.s.). Fracture gap twisting and opening did not differ significantly between the four constructs for the Hoffa fragment, while plate-augmented constructs provided less fracture opening of the intercalary fragment compared to isolated posteroanterior screw fixation ( p < 0.01). Conclusions: Plate-augmented posteroanterior screw fixation of comminuted Letenneur type IIb Hoffa fractures provided greater biomechanical stability than isolated posteroanterior screw fixation. While additional lateral or double plate fixation improves the stability of both the intercalary and Hoffa fragment, posterior plating stabilized only the Hoffa fragment.

Purpose: Current literature lacks recommendations regarding proper fixation of tibial tubercle avulsion fractures involving the proximal tibial epiphysis (Ogden fractures). Therefore, the aim of this study was to compare isolated apophyseal screw fixation and additional fixation techniques in Ogden fractures. Methods: Two different types of apoepiphyseal tibial tubercle avulsion fractures were created in 40 proximal tibiae according to the modified Ogden classification: (1) Ogden type IIIA and (2) Ogden type IV. The fractures were fixed with either isolated apophyseal screws or additionally with a medial plate or epiphyseal screws. All specimens were biomechanically tested under progressively increasing cyclic loading until failure, while capturing the interfragmentary movements with motion tracking. Results: Augmentation of apophyseal screw osteosynthesis by a medial plate in Ogden IV fractures or epiphyseal screws in Ogden IIIA fractures exhibited significantly higher cycles to failure and failure loads ( P < 0.05), and significantly less axial displacement ( P < 0.05) compared to isolated apophyseal screw fixation. Fixation of Ogden type IIIA fractures resulted in significantly less axial displacements and higher construct stiffness, cycles to failure and failure loads compared to Ogden type IV fracture ( P < 0.001). Fracture gap opening did not differ significantly between the fixation techniques. Conclusions: Augmented apophyseal screw fixation of apoepiphyseal tibial tubercle avulsion fractures provides greater biomechanical stability than isolated apophyseal screw fixation. Regardless of fixation technique, Ogden type IV fractures are more unstable than Ogden type IIIA fractures, so an individualized treatment strategy based on fracture morphology is crucial. In case of an Ogden type IIIA or Ogden type IV fracture, surgeons should consider adding epiphyseal screws or a medial plate osteosynthesis to apophyseal screw fixation to best neutralize forces of the extensor mechanism, as long as the often compromised soft tissue envelope can tolerate greater surgical invasiveness.