Biomechanical comparison of distal femoral fracture fixation: Polyaxial vs. uniaxial locking screws with different blocking screw configurations in retrograde femoral nailing.

INTRODUCTION: Clinical studies have indicated reduced reliance on blocking screws with the introduction of polyaxial locking nails, yet the biomechanical superiority of polyaxial locking over blocking screws remains unverified, specifically for distal dia-metaphyseal femur fractures. HYPOTHESIS: We hypothesized that the combination of multiaxial locking using three screws and parallel locking reinforced by two blocking screws would result in superior outcomes compared to utilizing only parallel locking with two screws and one blocking screw. MATERIALS AND METHODS: Third-generation custom-made femur models representing AO/OTA 32 A1.2 dia-metaphyseal comminuted oblique fractures were divided into four groups (n=10/group). Group A employed distal fixation with three 4.5-mm polyaxial screws. Group B used two parallel locking screws and two blocking screws, Group C used two parallel locking screws and one blocking screw, and Group D used only two parallel screws. Specimens underwent axial and torsional load testing to assess fatigue strength, ultimate strength, axial stiffness (N/mm), torsional stiffness (N/mm/deg), axial load to failure (N), torsional load to failure (N/mm), coronal and sagittal angulations, and fracture site collapse. RESULTS: Group C exhibited statistically superior torsional stiffness compared to Groups B and D (p=0.039 and p=0.034, respectively). Axial load to failure was highest in Group B and lowest in Group D (p=0.032). Group C demonstrated the highest torsional strength, while Group B exhibited the lowest (p=0.006). Coronal displacement was greatest in Group B, while Group A showed the highest resistance (p=0.009). Group A demonstrated the greatest resistance to fracture site collapse, with the weakest specimens observed in Groups B and C (p=0.01). DISCUSSION: The performance of a single laterally positioned blocking screw is comparable to using two blocking screws. Medial positioning of a second blocking screw is unnecessary for stability enhancement. Multiaxial locking prevents fracture site collapse and coronal plane angulation more effectively than other methods. Multiaxial locking and/or parallel screws with a single laterally positioned blocking screw provide superior stiffness and stability for treating unstable dia-metaphyseal distal femoral fractures. LEVEL OF EVIDENCE: N/A.

Ultrasonographic comparison of bilateral patellar tendon dimensions in patients treated via intramedullary tibial nailing using a transpatellar approach.

OBJECTIVE: One of the most common complications following intramedullary nailing of a tibial shaft fracture is anterior knee pain. The etiology of pain remains unclear. Patellar tendon entry point is the most suspected reason for anterior knee pain. This study, sonographically examined the patellar tendons of patients treated via intramedullary nailing. METHODS: Thirty-two patients with a tibial shaft fracture requiring intramedullary nailing via a transpatellar approach were included in the study. After all patients were grouped by reference to the presence of anterior knee pain, bilateral patellar tendon ultrasonography was performed. RESULTS: Thirty-two patients were included in the study. Patients were measured postop average in 38.3 months (10th months - 84th months). It was determined that 10 patients of total 32 (31.3%) had anterior knee pain. There were no statistically differences between study groups in the length of patellar tendon. In the painless group; patellar tendon was wider and thicker in the operated side than the non operated side. The mean differences in the thickness between operated side versus non - operated side of the painless group were 5.3 ± 1.8 in the operated side and 3.9 ± 1.4 in the non - operated side (p = 0.007 < 0.05). The corresponding values for width of the patellar tendon was 29.6 ± 3.3 in the operated side and 27.6 ± 3.8 in the non - operated side (p = 0.007 ˂ 0.05). As a result, there were no statistically significant differences between width and thickness of the patellar tendons in the painful group, on the contrary, in the painless group; patellar tendons were wider and thicker in the operated side than those in the non - operated side. Mean values for thickness of the operated and non-operated side were 5.9 ± 2.3 and 4.2 ± 2.0, respectively (p = 0.059 > 0.05). Mean values for width of the operated and non-operated side were 30.2 ± 4.5 and 28.5 ± 4.0, respectively (p = 0.103 > 0,05). CONCLUSION: Based on the ultrasonographic investigation of their patellar tendons after intramedullary nailing of a tibial shaft fracture, in the painless patients group; the patellar tendon was wider and thicker in the operated side than the non - operated side, however, in the painful patients there were no statistically significant differences between this parameters. Although the number of patients was not sufficient to conclude precise relation between patellar tendon entry point and anterior knee pain, we determined that thicker and wider tendon might be less related to anterior knee pain. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Effect of Repeated Sterilization by Different Methods on Strength of Carbon Fiber Rods Used in External Fixator Systems.

OBJECTIVES: We aimed to study the effects of repeated sterilization, using different methods, on the carbon fiber rods of external fixator systems. METHODS: We used a randomized set of 44 unused, unsterilized, and identical carbon fiber rods (11 × 200 mm), randomly assigned to 2 groups: unsterilized (4 rods) and sterilized (40 rods). The sterilized rods were divided into 2 groups, those sterilized in an autoclave and those sterilized using hydrogen peroxide. These were further divided into 5 subgroups based on the number of sterilization repetition to which the fibers were subjected (25, 50, 75, 100, and 200). A bending test was conducted to measure the maximum bending force, maximum deflection, flexural strength, maximum bending moment and bending rigidity. We also measured the surface roughness of the rods. RESULTS: An increase in the number of sterilization repetition led to a decrease in maximum bending force, maximum bending moment, flexural strength, and bending rigidity, but increased maximum deflection and surface roughness (P < 0.01). The effect of the number of sterilization repetition was more prominent in the hydrogen peroxide group. CONCLUSIONS: This study revealed that the sterilization method and number of sterilization repetition influence the strength of the carbon fiber rods. Increasing the number of sterilization repetition degrades the strength and roughness of the rods.

Surgical treatment of displaced intraarticular calcaneus fractures using anatomical lateral frame plate.

BACKGROUND: The present study evaluated the results obtained from the anatomical lateral frame plate treatment of displaced intraarticular calcaneus fractures. METHODS: Overall, 14 displaced intraarticular fractures of 13 patients (3 females, 10 males; Mean age, 37.5 years) were included in the present study. Surgery was performed using widened lateral approach and supported by auto grafts following joint line reduction in all patients. They were then fixated by anatomical lateral frame plate. All the joints were stabilized by casting after the operation. All patients were prescribed controlled and full weight bearing at 6-8th and 12th weeks, respectively. RESULTS: Mean follow-up of patients was 28 months. The fractures were classified according to Sanders system. Clinical scoring of the patients was performed according to American Orthopaedic Foot and Ankle Society, Creighton-Nebraska, and Maryland systems. According to these systems, the mean scores of the patients were 83.7, 75.7, and 88.5 respectively. CONCLUSION: In the present study, we have defined the results of anatomical lateral frame plate treatment in patients with displaced intraarticular calcaneus fractures. We have obtained clinically and radiologically satisfactory results with the anatomical compatibility of plate to the lateral surface of the calcaneus.