OBJECTIVE: To establish finite element models of different preserved angles of osteonecrosis of the femoral head (ONFH) for the biomechanical analysis, and to provide mechanical evidence for predicting the risk of ONFH collapse with anterior preserved angle (APA) and lateral preserved angle (LPA). METHODS: A healthy adult was selected as the study object, and the CT data of the left femoral head was acquired and imported into Mimics 21.0 software to reconstruct a complete proximal femur model and construct 3 models of necrotic area with equal volume and different morphology, all models were imported into Solidworks 2022 software to construct 21 finite element models of ONFH with LPA of 45°, 50°, 55°, 60°, 65°, 70°, and 75° when APA was 45°, respectively, and 21 finite element models of ONFH with APA of 45°, 50°, 55°, 60°, 65°, 70°, 75° when LPA was 45°, respectively. According to the physiological load condition of the femoral head, the distal femur was completely fixed, and a force with an angle of 25°, downward direction, and a magnitude of 3.5 times the subject's body mass was applied to the weight-bearing area of the femoral head surface. The maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head were calculated and observed by Abaqus 2021 software. RESULTS: The finite element models of ONFH were basically consistent with biomechanics of ONFH. Under the same loading condition, there was stress concentration around the necrotic area in the 42 ONFH models with different preserved angles composed of 3 necrotic areas with equal volume and different morphology. When APA was 60°, the maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head of the ONFH models with LPA<60° were significantly higher than those of the models with LPA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with LPA≥60° ( P>0.05). When LPA was 60°, each index of the ONFH models with APA<60° were significantly higher than those of the models with APA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with APA≥60° ( P>0.05). CONCLUSION From the perspective of biomechanics, when a preserved angle of ONFH is less than its critical value, the stress concentration phenomenon in the femoral head is more pronounced, suggesting that the necrotic femoral head may have a higher risk of collapse in this state.
Adult ; Humans ; Femur Head/surgery* ; Finite Element Analysis ; Stress, Mechanical ; Femur/diagnostic imaging* ; Femur Head Necrosis/surgery*

By discussing different ways on prediction, prevention and treatment of femur head necrosis (FHN), to provide a theory reference for future clinical application. By searching, reading and summarizing related-literatures through CNKI, VIP, CBM and foreign-related literature, to sum up the relevance methods and techniques of currently used. It was found that imaging study (especially X-ray and MRI) was of great importance in prediction. There were several ways (both non-surgical or surgical) for prevention and treatment. FHN collapse was affected by many factors, but most of the researches were all focus on one aspect of the mechanism and based on small samples. It is necessary to have a research with a large sample and to compare the effect on different treatment. Early and effective imaging inspection is needed for high risk group of FHN; possibility of collapse should be predicted for existing FHN; core decompression or vascularized bone grafting are required for collapse of high risk group. Early prediction and treatment are essential for FHN patients.
Bone Transplantation ; Decompression, Surgical ; Femur Head Necrosis ; complications ; diagnostic imaging ; surgery ; Humans ; Magnetic Resonance Imaging ; Tomography, X-Ray Computed

Based on the unilateral CT images of a clinical patient in stage III for avascular necrosis of femoral head, three-dimensional finite element models of proximal femur are established, including normal model, necrosis model and prothetic model. Based on the same set of CT images, the material properties are assigned to the three finite element models respectively. Finally, the process of bone grafting for avascular necrosis of femoral head is simulated with finite element analysis. The results indicate that when the necrosis parts of femoral head are removed, the stress and displacement of proximal femur increase accordingly, and after the surgical operation of bone grafting, the stress and displacement of proximal femur can decrease effectively and become closer to the normal state. All the results indicate that the bone grafting operation is effective and reliable.
Bone Transplantation ; methods ; Computer Simulation ; Femur Head Necrosis ; diagnostic imaging ; surgery ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Models, Biological ; Tomography, X-Ray Computed

BACKGROUND: Early stage osteonecrosis of the femoral head (ONFH) has many treatment options including core decompression with implantation of a tantalum rod. The purpose of this study was to evaluate clinical and radiological outcomes and potential complications during conversion total hip arthroplasty (THA) in such patients. METHODS: Six male patients (8 hips) underwent THA subsequent to removing a tantalum rod (group I) from April 2010 to November 2011. We retrospectively reviewed the medical records of these patients. We enrolled 12 age- and sex-matched patients (16 hips) during the same period, who had undergone primary THA without a previous operation as the control group (group II). All patients were followed for at least 3 years. We checked the Harris hip score (HHS), operative time, and volume of blood loss. Radiological results, including inclination, anteversion of the acetabular cup, presence of periprosthetic osteolysis, and subsidence of femoral stem were checked at the last follow-up. RESULTS: The mean preoperative HHS values were 56.5 (range, 50 to 62) and 59.1 (range, 42 to 70) in groups I and II, respectively. The HHS improved to 96.0 (range, 93 to 100) and 97.6 (range, 93 to 100), respectively, at the 3-year follow-up (p = 0.172). Mean operation time was 98.8 minutes (range, 70 to 120 minutes) in group I and 77.5 minutes (range, 60 to 115 minutes) in group II (p = 0.006). Total blood loss volumes were 1,193.8 mL (range, 960 to 1,360 mL) and 944.1 mL (range, 640 to 1,280 mL) in groups I and II, respectively (p = 0.004). No significant differences in inclination or anteversion of acetabular cup and no evidence of osteolysis or subsidence of the femoral stem were reported in either group in radiological follow-up results. However, one case of squeaking occurred in group I during the follow-up. CONCLUSIONS: The two groups showed no clinical or radiological differences except extended operative time and increased blood loss. However, the incidence of squeaking (1 of 8 hips) was higher, as compared to the control group or previously reported values.
Adult ; *Arthroplasty, Replacement, Hip/adverse effects/methods/statistics & numerical data ; Case-Control Studies ; *Decompression, Surgical/adverse effects/methods/statistics & numerical data ; Femur Head/diagnostic imaging/surgery ; Femur Head Necrosis/diagnostic imaging/*surgery ; Humans ; Male ; Postoperative Complications ; Reoperation ; Retrospective Studies ; Tantalum/*therapeutic use ; Tomography, X-Ray Computed ; Treatment Outcome