Biomechanical comparison of fixation methods on third-generation femoral composite bone models in Pauwels type 3 femoral neck fractures: Contribution of the medial buttress plate to fixation.

OBJECTIVE: To compare the use of cannulated screws in an inverted triangular configuration, medial buttress plates, and the combination of these 2 fixation methods in the treatment of Pauwels type 3 femoral neck fractures. METHODS: Twenty-eight anatomical composite third-generation femoral bone models were divided into 4 groups. The control group (group 1) was formed with 7 third-generation intact bone models. The fracture model was created with a 70° cutting block to fit 21 Pauwels type 3 fracture configurations. Seven models were fixed with an isolated 3.5 mm one-third semi-tubular medial buttress plate (group 2), 7 were fixed in an inverted triangular configuration with 6.5 mm cannulated screws (group 3), and 7 were fixed using a combination of 6.5 mm cannulated screws and a medial buttress plate (group 4). Cyclic loading was applied using axial forces ranging from 60 N to 600 N and moments ranging from 0.7 Nm to 7.0 Nm for 500 cycles. Once the cyclic loading stage was completed, the loads were removed from the system, and the quasi-static loading stage was employed to determine the stiffness and failure forces of the system under both axial and torsional forces. Quasi-static tests were performed with an axial speed of 1.8 mm/min and a torsional speed of 4.5°/min. The biomechanical properties of all groups were examined in terms of axial stiffness, torsional stiffness, and maximum axial force parameters. RESULTS: The stiffness values of groups 1, 2, 3, and 4 were 303 ± 35.8 N/mm, 159.6 ± 25 N/mm, 232 ± 35.9 N/mm, and 366.9 ± 58 N/mm, respectively, under axial forces (P < .01); 2172.7 ± 252.1 Nmm/°, 1225.3 ± 238.6 Nmm/°, 2123 ± 359.4 Nmm/°, and 2721.85 ± 304 Nmm/°, respectively, under torsional moments (P < .01); and 2072.1 ± 256.1 N, 1379.9 ± 290.6 N, 2099.1 ± 454.2 N, and 2648.4 ± 364.6 N, respectively, under the maximum force (P < .01). CONCLUSION: This study showed that in the fixation of Pauwels type 3 fractures formed on third-generation bone models, the utilization of half-thread cannulated screws in an inverted triangle configuration, along with a medial buttress plate, provided stronger fixation compared to the remaining implant groups and the control group. According to the evaluation of the parameters, the isolated application of a medial buttress plate had poorer biomechanical properties than other fixation methods.

Effect of transported segment size on the new bone formation of the rabbit femur in the Ilizarov bone transport method.

OBJECTIVE: This study aimed to compare histological and radiological union in the bone transport of 3 segments of different sizes to reconstruct the rabbit femur's bone defects. METHODS: Thirty rabbits were divided into 3 groups; a 1-cm defect was created in the femur in all rabbits. The length of the segment to be transferred was 10% of the femur length in group 1, 15% in group 2, and 20% in group 3. All defects were reconstructed by applying bone transport. At the end of the consolidation period, the distraction zone was compared radiologically and histologically. RESULTS: While there was no radiological difference between the groups, the highest histological scores were obtained from group 3. Osteocalcin staining revealed similar involvement in groups 2 and 3, butless involvement in group 1. CONCLUSION: Evidence from this study has shown that as the size of the segment used for bone transport increases, more stable fixation and better histological union tissue can be obtained in the rabbit femoral defect model.

Biomechanical and fracture characteristics of different filling and fixation methods applied to various proximal tibial metaphyseal defect sizes in an ovine model.

BACKGROUND: Ideal treatment method based on the size of the defect in local aggressive bone tumors is yet to be described. We evaluated the mechanical behavior of different fixation methods for various defect sizes located in the proximal tibia. METHODS: Ninety-one sheep tibiae were distributed in five groups. Each study group was further divided into three subgroups, forming 25%, 50%, and 75% metaphyseal defects. The five groups were divided as follows: 1) control group where tibiae remained intact (n = 7); 2) isolated defect created, without filling (n = 21); 3) filling with cement (n = 21); 4) application of two subchondral cortical screws in addition to cement (n = 21); and 5) application of plate-screw fixation in addition to cement (n = 21). A loading test simulating the axial load applied by the distal femur to the tibia plateau was performed. The maximum failure load was compared between groups according to the defect size and fixation method. FINDINGS: In 25% defects, group 5 had significantly higher failure load than other groups. However, in 50% and 75% defects, additional fixation did not increase the failure load. Also, additional screw fixation did not increase failure load in all defect sizes. There was a significant positive correlation between fracture morphology and defect size, fixation method, and failure load. INTERPRETATION: Additional plate-screw fixation would increase the stability in defects ≤25%. In defects ≥50%, additional fixation does not increase stability. Screw fixation in addition to cementing does not increase stability in all defect sizes.

Cementless rectangular stems yield satisfactory results in osteoporotic bones.

BACKGROUND: The present study aims to investigate the effects sof osteoporosis on prosthesis survival by comparing the femoral stem survival rates of patients with poor and relatively good bone quality. METHODS: We retrospectively investigated 61 patients with collum femoris fractures who were treated with cementless rectangular stems between 2011 and 2015 in the Orthopaedics and Traumatology Clinic of Taksim Training and Research Hospital. The preoperative pelvic anterior-posterior radiographs of the patients were evaluated. The patients were evaluated according to the Dorr classification, and no case with a type A femur was found. The patients were divided into two groups as advanced osteoporotic type C and moderate osteoporotic type B. Thirty patients were type B according to the Dorr classification and 31 were osteoporotic type C. RESULTS: The femoral component survival was evaluated using the Engh and ARA criteria. The relationship of the ARA score with type B and type C groups was evaluated. The median ARA score was five (min 3-max 6) for both types. These two groups were also statistically compared concerning the ARA scores using the Mann-Whitney U test, which revealed no statistically significant difference (p=0.24 >0.05). The Engh values, another criterion for the survival of femoral components, were also compared. The median Engh values were 16.5 (min 9-max 24) for the Dorr type B group and 14 (min 9-max 24) for the type C group. According to the Mann-Whitney U test, there was no significant difference between the Engh values of the two groups (p=0.061 >0.05). Lastly, no statistically significant difference was found in the ARA or Engh loosening scores between the type C advanced osteoporotic group and the type B moderate osteoporotic group. CONCLUSION: Our study supports the conclusion that cementless hip arthroplasty can be applied even in advanced elderly and osteoporotic patients without additional intraoperative or postoperative risks.

Behaviour and knowledge skill levels of orthopedic surgeons about radiation safety and fluoroscopy use: A survey analysis.

OBJECTIVE: The aim of this study was to evaluate the behaviour and knowledge skill levels of Turkish orthopedic surgeons about fluoroscopy usage and radiation safety. METHODS: The questionnaire, consisting of nineteen questions, was sent to orthopaedic surgeons and requested by a total of 323 surgeons online. The questions were about personal information, training and behaviours related to radiation and fluoroscopy usage, and the use of protective equipment. RESULTS: A total of 277 individuals completed the questionnaire. The answers of 180 surgeons whose working duration was more than 1 year and also who participated in at least one fluoroscopy requiring operation per week, were analysed. 22 (12%) participants answered that they were trained on fluoroscopy usage. Sixty people (33.3%) reported that they did not use any protective equipment regularly. The most commonly used protection methods were lead aprons 123 (68.3%). Thyroid protectors were used by 92 participants (52.1%). There was no significant difference between the groups when comparing the use of protective equipment according to the academic title. Only 19 (10.6%) of the surgeons noted that they used dosimeter regularly, and 15 (83.3%) of them reported that they controlled their dosimeters. CONCLUSION: In this study, Orthopedic surgeons were found not to be adequately trained about use and risks of fluoroscopy and also not to be equipped about methods for preventing radiation damage.