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

BACKGROUNDTreating developmental dysplasia of the hip is often challenging. The difficulties include not only the hip surgery itself but also the treatment of the associated lower-limb valgus deformity. However, there have been very few studies on such deformity in patients with developmental hip dysplasia. In this study, we investigated the prevalence and severity of lower-limb valgus deformity, along with the relationship between the severity of valgus deformity and mechanical alterations of the hip or the ipsilateral knee.

METHODSTwo hundred and six affected lower limbs of 116 adult patients with untreated developmental dysplasia of the hip were included in the study, grouped according to the severity of hip dysplasia. Each study participant's radiographs were measured to quantitatively evaluate the mechanical axis deviation of the lower limb, and further to evaluate the prevalence and severity of the lower-limb valgus deformity. Some mechanical alterations of the hip and the ipsilateral knee were also measured on the radiographs.

RESULTSOf the affected lower limbs, 14.1% had valgus deformities. Study participants with Crowe type III hip dysplasia had the most severe deformity and the highest prevalence of deformity. Severity of valgus deformity had a strong positive correlation with the lateral migration of the femoral head but not with the superior migration. A decreased lateral distal femoral angle contributed to the lower-limb valgus deformity, and the lateral distal femoral angle had a strong negative correlation with the severity of valgus deformity.

CONCLUSIONSHip dysplasia is commonly associated with lower-limb valgus deformity, and the severity of the lower-limb valgus deformity is mostly affected by lateral migration but not superior migration of the femoral head. The valgus deformity may originate mainly in the distal femur, in addition to the hip joint itself. These findings can be taken into account when planning to treat the patients with hip dysplasia.

Adolescent ; Adult ; Aged ; Female ; Femur Head ; diagnostic imaging ; pathology ; surgery ; Hallux Valgus ; diagnostic imaging ; pathology ; surgery ; Hip Dislocation, Congenital ; diagnostic imaging ; pathology ; surgery ; Hip Joint ; diagnostic imaging ; pathology ; surgery ; Humans ; Joint Deformities, Acquired ; diagnostic imaging ; pathology ; surgery ; Male ; Middle Aged ; Radiography ; Young Adult

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

OBJECTIVESTo investigate the safe distance from the tip of the cannulated screw to the apex of the femoral head, and to avoid cutting out of the cannulated screws from the femoral head.

METHODSFrom November 2007 to April 2008, the placement configuration of the cannulated screws in the femoral head on the anteroposterior (AP) and lateral view was investigated. And the relation between the three-dimensional configuration and the two-dimensional perpendicular view of the femoral head to establish a solid geometry formula was analyzed. According to the configuration, the distances from the tips of different cannulated screws to the apex of the femoral head to confirm the screws placement within the femoral head was measured.

RESULTSThe actual risk of cutting out of the cannulated screws varied according to the different placement of the cannulated screws in the femoral head, even if the screw tips were within the femoral head on the AP and lateral radiograph. The mean diameter of femoral head was 49.8 mm. If the cannulated screw is in the center of femoral head on the lateral view, the cannulated screw would not cut out as long as it was in the femoral head on the AP view. When the angle was 22.5°on the lateral view, and under 22.5°on the AP view, the distance from the screw tip to the apex of the femoral head would exceeded 2.2 mm. If the angle > 45°on the AP view, the distance would exceed 9.6 mm. When the angle was 45°on the lateral view, and under 22.5°on the AP view, the distance would exceed 8.2 mm. When the angle > 45°on the AP view, the distance would exceed 17.7 mm. When the angle was 67.5°on the lateral view, the distance would exceed 23.1 mm on AP view.

CONCLUSIONSIf the cannulated screw is in the center of femoral head on the lateral view, the cannulated screw won't cut out as long as it is in the femoral head on the AP view. The angle is larger on the AP and lateral view (especially on the lateral view), and the distance is longer.

Adult ; Aged ; Bone Screws ; Female ; Femoral Neck Fractures ; diagnostic imaging ; surgery ; Femur Head ; diagnostic imaging ; surgery ; Fluoroscopy ; Fracture Fixation, Internal ; methods ; Humans ; Intraoperative Care ; Male ; Middle Aged ; Young Adult

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

OBJECTIVETo evaluate the feasibility and the clinical practicality of the design about the hollowed titanium stick supporting the femoral head and preventing it from collapsing.

METHODSFrom Jan.2003 to Jun.2007, 36 patients (46 hips) diagnosed as cystis degeneration of the femoral head were treated by surgical operation, including 20 males and 16 females with an average age of 40 years ranging from 18 to 56 years old, and the course of the disease was from 10 to 24 months (16 months on average). According to ARCO staging,there were 24 patients (34 hips) in NFH II, of which 11 hips were II a stage, 13 hips were II b stage and 10 hips were II c stage; there were 6 patients diagnosed as osteofibrous,4 patients as simple bone cyst and 2 patients as chondromyxoid fibroma. Under X-ray the percutaneous narrow core decompression and focus infection elimination were performed and supported the sclerotin under the cartilage with titanium stick. The patients were followed-up at the first, third, sixth, twelfth, twenty-fourth and thirty-sixth month after the operation. The clinical evaluation was done by X-ray and the indexes included stable, unstable and abortive. The data was analyzed by Fisher exact probility and the suviaval rate was analyzed by Kaplan-Meier suviaval curve using statistical soft ware SPSS13.5.

RESULTSThere were no unstable or failure cases on each period from the 1st month to the 12th month after the operation, indicating that the supporting effect of the titanium stick was exact during 12 months after the operation. There were unstable and failure cases from the 12th month to the 24th month after the operation, which were mainly in stage NFH II c but the comparision of the stable rate in this period and 12 months after the operation had no obvious statistical differences (P>0.05) indicating that the supporting effect of the titanium stick was feasible during the stage. One of the unstable cases deteriorated and failed but there were no new unstable cases, both the stable rate and the unstable rate had no change and the failure rate rose on the 36th month after the operation. The compar- ision of the stable rate on each period after the operation had no obvious difference (P=0.197>0.05), which indicated that the supporting effect of the titanium stick was persistent. By the difference of the etiology the three-year survival rate of the relevant NFH II c pathological changes was the lowest-70% and the survival rate of the pathological changes induced by other etiological factors was 90.2%.

CONCLUSIONThe design about the hollowed titanium stick supporting the collapsed femoral head is feasible. Using the hollowed titanium stick to support the femoral head and prevent it from collapsing is pragmatic in the clinical and the effect is positive, however, when it comes to the NFH II c pathological changes, the choice should be made discreetly.

Adolescent ; Adult ; Feasibility Studies ; Female ; Femur Head ; diagnostic imaging ; surgery ; Follow-Up Studies ; Humans ; Internal Fixators ; adverse effects ; Male ; Middle Aged ; Prosthesis Design ; methods ; Titanium ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVETo evaluate the outcome of total hip arthroplasty (THA) with cementless cups and femoral head autografts for patients with hip dysplasia and osteoarthritis.

METHODSBetween 1995 and 2002, we implanted 23 cementless cups and femoral head autografts in 20 patients with hip dysplasia and osteoarthritis. In this study, a retrospective study was made on 21 hips in 20 patients (18 females and 2 males, aged 50 years on an average) with developmental hip dysplasia treated by THA with a cementless cup and femoral head autograft. The acetabular cup was placed at the level of the true acetabulum and all the patients required autogenous femoral head grafts due to acetabular deficiency. The average rate of the acetabular cup covered by the femoral head autograft was 31% (ranging from 10% to 45%). Eight hips had less than 25% cup coverage and thirteen between 25% and 50%. The average follow-up period was 4.7 years (range, 1-8 years). The replacing outcome was evaluated by modified Harris hip score. Preoperative and follow-up radiographs were made.

RESULTSAll the autografts were united to the host bones. No autograft was collapsed or no component from the hip was loosed in all the patients. According to the modified Harris hip score, the average hip score increased from 46 before operation to 89 at the final review. Before operation, the leg-length discrepancy was greater than 2 cm in all the patients except one with bilateral hip dysplasia. After operation, only 2 out of 20 patients had a leg-length discrepancy greater than 1 cm. Three hips showed minor bone resorption in the lateral portion of the graft, which did not support the cup. Three hips developed Grade 1 Brooker heterotopic ossification and one developed Grade 2.

CONCLUSIONSTHA with a cementless cup and a femoral head autograft for patients with osteoarthritis resulted from hip dysplasia can result in favorable outcomes. This method can provide reliable acetabular fixation and restore the acetabular bone stock in patients with developmental hip dysplasia when the cementless cup covered by the graft does not exceed 50%.

Adult ; Aged ; Arthroplasty, Replacement, Hip ; methods ; Bone Cements ; Bone Transplantation ; methods ; China ; Cohort Studies ; Combined Modality Therapy ; Female ; Femur Head ; surgery ; Follow-Up Studies ; Hip Dislocation ; diagnostic imaging ; surgery ; Hip Prosthesis ; Humans ; Male ; Middle Aged ; Osteoarthritis, Hip ; diagnostic imaging ; surgery ; Prosthesis Design ; Prosthesis Failure ; Radiography ; Recovery of Function ; Retrospective Studies ; Risk Assessment ; Severity of Illness Index ; Transplantation, Autologous ; Treatment Outcome