Femoral head collapse is a possible complication after surgical treatment of femoral neck fractures. The purpose of this study was to examine whether implantation of a Sliding Hip Screw (SHS) or an X-Bolt could increase the risk of femoral head collapse. Similar to traditional hip screws, the X-Bolt is implanted through the femoral neck; however, it uses an expanding cross-shape to improve rotational stability. The risk of collapse was investigated alongside patient factors, such as osteonecrosis. This numerical study assessed the risk of femoral head collapse using linear eigenvalue buckling (an established method [1]), and also from the maximum von Mises stress within the cortical bone. The femoral head was loaded using the pressures reported by Yoshida et al. for a patient sitting down (reported to put the femoral head at greatest risk of collapse [2]), with a peak pressure of 9.4 MPa and an average pressure of 1.59 MPa. The femur was fixed in all degrees of freedom at a plane through the femoral neck. The X-Bolt and SHS were implanted in accordance with the operative techniques. The femoral head and implants were meshed with quadratic tetrahedral elements, and cortical bone was meshed with triangular thin shell elements. A converged mesh seeding density of 1.2 mm was used. All models were create and solved using ABAQUS finite element software (version 6.12, Simulia, Dassault Systèmes, France). The influence of implant type and presence was examined alongside a variety of patient factors:. Osteonecrosis, modelled as a cone of bone of varying angle, and varying modulus values. Cortical thinning. Reduced cortical modulus. Femoral head size. Twenty-two finite element models were run for each implant condition (intact; implanted with the X-Bolt; implanted with a SHS), resulting in a total of 66 models. The finite element models were validated using experimental tests performed on five 4. th. generation composite Sawbones femurs (Malmö, Sweden), and verified against previously published results [1]. No significant difference was found between the X-Bolt and the SHS, for either critical buckling pressure (p=0.964), or the maximum von Mises stress (p=0.274), indicating no difference in the risk of femoral head collapse. The maximum von Mises stress (and therefore the risk of collapse) within the cortical bone was significantly higher for the intact femoral head compared to both implants (X-Bolt: p=0.048, SHS: p=0.002). Of the factors examined, necrosis of the femoral head caused the greatest increase in risk. The study by Volokh et al. [1] concluded that deterioration of the cancellous bone underneath the cortical shell can greatly increase the risk of femoral head collapse, and the results of the present study support this finding. Interestingly the presence of either an X-Bolt or SHS implant appeared to reduce the risk of femoral head collapse

Introduction. Osteonecrosis (ON) is one of the most debilitating skeletal disorders. Most patients with ON of the femoral head eventually require surgery, usually total hip arthroplasty, within a few years of disease onset. Previous reports have shown that alendronate reduces osteoclastic activity and reduces the incidence of femoral head collapse in osteonecrotic hips. A randomized study to examine the ability of alendronate to delay or prevent femoral head collapse was performed. Methods. From June 2005 to December 2006, sixty four patients were enrolled and randomly assigned to alendronate or placebo. Five patients were excluded from the analysis because of their failure to adhere to the study protocol. Disease progression was evaluated using radiographs and magnetic resonance imaging (MRI). Results. While the proportion of patients in the alendronate group who underwent total hip arthroplasty was 13% (4 of 31 patients), the proportion of patients undergoing the procedure in the placebo group was 29% (8 of 28 patients; p=0.22, cumulative incidence between the two groups by log-rank test). As such, there was a numerical reduction in the rate of total hip arthroplasty in the alendronate group compared to placebo that did not achieve statistical significance likely because the study was originally powered to detect a between-group difference based on event rates of 35.7% and 3.4% in the placebo and alendronate groups, respectively. Conclusion. Alendronate treatment shows promise for the treatment of atraumatic osteonecrosis. However, additional studies are needed to confirm our results. Osteotomy or bone grafting still remains the procedure of choice for osteonecrosis of the femoral head prior to collapse. Disclosure. The study was supported in part by Merck Sharp & Dohme (I.A) Corp. Taiwan Branch. All these schools received some financial reimbursement for the study

Femoral head collapse due to avascular necrosis (AVN) is a relatively rare occurrence following intertrochanteric fractures; however, with over thirty-thousand intertrochanteric fractures per year in England and Wales alone, and an incidence of up to 1.16%, it is still significant. Often patients are treated with a hip fixation device, such as a sliding hip screw or X-Bolt. This study aimed to investigate the influence of three factors on the likelihood of head collapse: (1) implant type; (2) the size of the femoral head; and (3) the size of the AVN lesion. Finite element (FE) models of an intact femur, and femurs implanted with two common hip fixation designs, the Compression Hip Screw (Smith & Nephew) and the X-Bolt (X-Bolt Orthopaedics), were developed. Experimental validation of the FE models on 4. th. generation Sawbones composite femurs (n=5) found the peak failure loads predicted by the implanted model was accurate to within 14%. Following validation on Sawbones, the material modulus (E) was updated to represent cancellous (E=500MPa) and cortical (E=1GPa) bone, and the influence of implant design, head size, and AVN was examined. Four head sizes were compared: mean male (48.4 mm) and female (42.2 mm) head sizes ± two standard deviations. A conical representation of an AVN lesion with a lower modulus (1MPa) was created, and four different radii were studied. The risk of head collapse was assessed from (1) the critical buckling pressure and (2) the peak failure stress. The likelihood of head collapse was reduced by implantation of either fixation device. Smaller head sizes and greater AVN lesion size increased the risk of femoral head collapse. These results indicate the treatment of intertrochanteric fractures with a hip fixation device does not increase the risk of head collapse; however, patient factors such as small head size and AVN severity significantly increase the risk

Similar to the radiological findings in rapidly destructive arthrosis of the hip joint (RDA), subchondral insufficiency fracture of the femoral head (SIF) can result in progressive femoral head collapse of unknown etiology. We thus examined the osteoclast activity in hip joint fluid in SIF with progressive collapse in comparison to that in RDA. Twenty-nine hip joint fluid samples were obtained intraoperatively with whole femoral heads from 12 SIF patients and 17 RDA patients. SIF cases were classified into subgroups based on the presence of ≥2mm collapse on preoperative radiographs: SIF with progressive collapse (n=5) and SIF without progressive collapse (n=7). The levels of tartrate-resistant acid phosphatase (TRACP)-5b, interleukin-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 were measured. Numbers of multinuclear giant cells at the subchondral region were assessed histopathologically using mid-coronal slices of each femoral head specimen. Median levels of all markers and median numbers of multinuclear giant cells in SIF with progressive collapse were significantly higher than those in SIF without progressive collapse, while there were no significant differences in SIF with progressive collapse versus RDA. Regression analysis showed that the number of multinuclear giant cells correlated positively with the level of TRACP-5b in joint fluid. This study suggests an association of increased osteoclast activity with the existing condition of progressive collapse in SIF, which was quite similar to the findings in RDA. Therefore, high activation of osteoclast cell may reflect the condition of progressive collapse in SIF as well as RDA

Introduction. For many years, minimally invasive joint-preserving regenerative therapy has been desired for the early stages of osteonecrosis of the femoral head (ONFH). In an animal study using adult rabbits, we reported that a single local injection of rhFGF-2-impregnated gelatin hydrogel, which has superior slow-release characteristics, suppresses the progression of femoral head necrosis. The purpose of this study was to evaluate the safety and clinical outcomes of a single local administration of rhFGF-2-impregnated gelatin hydrogel for the precollapse stage of ONFH. Patients and Methods: Ten patients with femoral heads up to precollapse stage 2 underwent a single local administration of 800-µg rhFGF-2-impregnated gelatin hydrogel and were followed up for two years. The eligibility criteria were age between 20 and 80 years and presence of ONFH at precollapse stage 1 or 2 according to the classification system for ONFH developed by the Japanese Investigation Committee of Health and Welfare. Primary outcomes included adverse events and complications. Secondary outcomes included changes in Harris Hip Scores (HHS), visual analog scale pain scores (VAS), the University of California, Los Angeles (UCLA) activity rating scores, radiological changes as determined via radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) of the hip joint. Results: We included five men (five hips) and five women (five hips), with a mean age of 39.8 years (range: 29–53 years) at the time of surgery. Eight patients had bilateral ONFH, three had already undergone THA on the contralateral side. Eight patients were receiving treatment with corticosteroid therapy, and two patients overused alcohol. Stage 1 and 2 disease was present in one and nine patients, respectively. One patient each had type A, type B, and type C1 disease, whereas seven patients had a type C2 lesion. All Adverse events were recovered without problem. The surgery was performed with a minimally invasive technique based core decompression (1 cm of skin incision), and walking was allowed from the day after surgery. Mean clinical scores improved significantly after three year compared with before surgery (before vs. after: VAS for pain, 21.2 vs. 5.3 mm; UCLA activity score 5.5 vs. 6.6; HHS, 81.0 vs. 98.4 points, respectively). There was only one case of femoral head collapse, and it had the greatest necrosis volume fraction and was considered to be in the early collapse stage at the time of operation. The other nine cases did not involve ONFH stage progression, and collapse was prevented. CT images and recent MRI postoperatively confirmed bone regeneration and reduction of the necrotic area. Conclusion: Clinical application of rhFGF-2-impregnated gelatin hydrogel for patients with precollapse stage of ONFH was feasible and safe. Our research is ongoing, further phase II multiple center study has been started in January 2016

Summary Statement. Osteonecrosis of the femoral head (ONFH) is a multifactorial skeletal disorder. S100A9 represseses angiogenesis and vessel integrity in ONFH. It also may function as a marker of diagnosis in ONFH. Introduction. Osteonecrosis of the femoral head (ONFH) is a multifactorial skeletal disorder characterised by ischemic deterioration, bone marrow edema and eventually femoral head collapse and joint destruction. Several surgical, pharmaceutical and non-invasive biophysical modalities have been employed to alleviate this joint disorder. Our proteomic analysis showed that ONFH patients displayed increased expression of S100A9 protein when compared with healthy volunteers. This study is designed to evaluate the pathogenesis of S100A9 on the patients of ONFH. Patients & Methods. We collected 56 patients with ONFH including stage I, II, III and IV and 14 health volunteers. 20 ml of peripheral venous blood is drawn from each subject or prior to general anesthesia for hip arthroplasty. We compared the ELISA of S100A9, Osteocalcin, TRAP-5b, sVCAM-1. Immunohistochemistry of S100A9, vWF and VEGF are compared using femoral head harvested from late stages of ONFH and femoral neck fracture when received hip arthroplasty. In vitro angiogenic assay was performed by tube formation assay. Results. There were significant elevation of S100A9 in the serum of ONFH patients then in healthy volunteers. sVCAM-1 and TRAP-5b were increased and Osteocalcin was decreased in ONFH patient when comapred with healthy volunteers. The expression of S100A9 protein in ONFH tissue was significantly higher than femoral neck fracture tissue. In tube formation assay, we found S100A9 and the serum of ONFH patient supressed angiogenesis in vascular endothelial cell culture. Discussion/Conclusion. The expression of S100A9 significantly increased in the serum and femoral head tissue of patients with ONFH. S100A9 also supressed angiogenesis expression. The results indicated that S100A9 represseses angiogenesis and vessel integrity in ONFH. It also may function as a marker of diagnosis in ONFH

Introduction. Subchondral insufficiency fractures of the femoral head (SIFFH) occur with normal or physiological stress in patients with poor bone quality. We evaluated the clinical characteristics of SIFFH. Methods. Nine cases of SIFFH were treated and followed up for an average of 9 months. Femoral head collapse (FHC) on radiographs was classified as minimal (< 2 mm), moderate (2-4 mm), and severe (> 4 mm). The severity of osteopenia was scored by Singh index (SI). Other characteristics of SIFFH were ascertained by assessing the clinical course as well as Body Mass Index (BMI) and magnetic resonance imaging (MRI). Results. There were 8 women and 1 man who had a mean age of 67 years. FHC was identified in 6 cases (1 minimal, 3 moderate, and 2 severe). SI scores ranged from 1 to 4. Mean BMI was 22.4 Kg/m. 2. In all affected hips, MRI demonstrated a subchondral fracture line with localized or diffuse bone-marrow-edema pattern in the femoral head. Initially, all cases were treated with conservative nonweight bearing therapy. In 7 of 9 cases, the pain decreased gradually and disappeared almost completely within 5 months regardless of the extent of FHC, SI score, and BMI. The remaining 2 cases (1 moderate and 1 severe FHC) were treated with total hip arthroplasty due to intractable pain. Conclusion. This study showed that conservative treatment could be considered as the first treatment choice for SIFFH independent of predisposing factors

Introduction. Osteonecrosis of the femoral head is a devastating disease in young patients and remains a challenge for clinicians and researchers alike. To increase understanding of the disease and produce effective treatments that preserve a patient's native hip, an animal model that mimics the disease process in humans, including collapse of the femoral head, is essential. Our goal was to create such a bipedal model by surgically inducing osteonecrosis in the femoral heads of chickens. Methods. A lateral approach to the proximal femur was used to access the hip, dislocate the femoral head, and sever the periosteal network of blood vessels. At 4, 8, 12, and 20 weeks after surgery, both the left (experimental) and right (control) femoral heads were harvested from 6 chickens for micro-CT and histological analysis. Results. Hematoxylin and eosin stained sections beginning at 4 weeks demonstrated trabecular bone loss, empty osteocyte lacunae, and new bone formation on existing trabeculae. By 20 weeks, subchondral cyst formation and femoral head collapse was observed. Micro-CT analysis of the operative hips compared to matched controls showed decreased bone volume (18% at 4 weeks, 36% at 8 weeks, 45% at 12 weeks), increased porosity (2.1%, 7.3%, 10.7%), and increased average pore diameter (13%, 18%, 37%). Conclusion. The results indicate that operative disruption of blood supply to the femoral head produces changes consistent with osteonecrosis, including progression to collapse, as seen in human end-stage disease. A successful osteonecrosis model provides the basis to test new therapies, such as bone graft substitutes seeded with stem cells and growth factors

Introduction. We have evaluated the circulation of the femoral head after multiple pinning for femoral neck fractures by bone SPECT. Methods. Forty-four patients (33 women, 11 men, who had a mean age of 67 years) were enrolled prospectively. Early and late bone SPECT images were obtained on 2 to 13 days and 3 months after surgery and follow-up periods were over 12 months (average, 29 months). Results. Seventeen cases showed normal uptake on early bone SPECT and healed successfully. Twenty-seven cases showed decreased uptake on early bone SPECT. Among these 27 cases, reperfusion was confirmed in 18 cases (66.7%) by late bone SPECT. The remaining 9 cases showed no recovery and the femoral heads were collapsed eventually. According to the Garden classification, osteonecrosis was found in 4 of 28 cases (14.3%) in Type I, 2 of, 15 cases (13.3%) in Type II, 3 of 6 cases (50%) in Type III and osteonecrosis was not detected in the one Type IV case. Conclusion. In summary, bone SPECT is very sensitive and vascular insufficiency could be found even in the early post-operative period. Cases with normal uptake showed successful union. But, bone SPECT in early post-operative periods cannot be used to predict final outcome, as 66.7% of cases were recovered from ischemia. Although osteonecrosis was higher in cases with displacement, we should be careful for impacted fractures (Type I) as the incidence of osteonecrosis was not low

Introduction. Osteonecrosis of the femoral head usually progresses to collapse in up to 70% to 80% of all cases. Previous studies have shown high failure rates with non-operative treatment, whereas, some surgical options including bone grafting, core decompression, osteotomy and arthroplasty have been recommended. Total hip arthroplasty and hemiarthroplasty, either cemented or cementless, are the last resort for improving the functional outcomes for the elderly. However, salvage of the femoral head in relatively young patients is widely advocated. Thus vascularized bone grafting has been recommended to salvage the collapsing femoral head. The purpose of this study was to evaluate the prognostic factors related to the outcome of the vascularized iliac bone grafting in the treatment of osteonecrosis of the femoral head. Methods. A retrospective case series review study is presented. Between April 1987 and April 2003, 47 patients (51 hips) in the authors' hospital underwent vascularized iliac bone grafting for the treatment of osteonecrosis of the femoral head. Three patients were lost to follow-up, thus, 44 patients (48 hips), 38 men and 4 women, were included in the study. All patients underwent operation by one experienced senior surgeon. Patients were grouped according to related risk factors, i.e., trauma, corticosteroid, alcohol, and an idiopathic group. A radiographic scale, the Ficat and Arlet classification system, was used for grading the osteonecrosis. We set the conversion to total hip arthroplasty as the end point for survival of vascularized iliac bone grafting in this study. Kaplan-Meier survivorship analysis was used to determine the significance with regard to the risk factors, age, Ficat and Arlet staging, gender, and side. Results. The Kaplan-Meier survivorship analysis showed that the 5-year overall rate of graft survival was 68.5% (95% confidence interval: 52.7% to 80.0%), 10-year overall rate of graft survival was 61.5% (95% confidence interval: 44.4% to 74.8%), and 61.5% (95% confidence interval: 44.4% to 74.8%) at 15 years. There was no significant difference between the groups regarding the prognostic factors of etiology, gender, side, and stage. The only significant parameter was the age that the patients older than 50 years had the worst 5-year survival rate of the femoral head (p<0.05). Conclusion. Vascularized bone grafting is a technically demanding procedure when compared to conventional core decompression or arthroplasty. However, this technique can preserve the femoral head from collapse and preclude the need for arthroplasty in young patients

The efficacy of β-tricalcium phosphate (β-TCP) loaded with bone morphogenetic protein-2 (BMP-2)-gene-modified bone-marrow mesenchymal stem cells (BMSCs) was evaluated for the repair of experimentally-induced osteonecrosis of the femoral head in goats.

Bilateral early-stage osteonecrosis was induced in adult goats three weeks after ligation of the lateral and medial circumflex arteries and delivery of liquid nitrogen into the femoral head. After core decompression, porous β-TCP loaded with BMP-2 gene- or β-galactosidase (gal)-gene-transduced BMSCs was implanted into the left and right femoral heads, respectively. At 16 weeks after implantation, there was collapse of the femoral head in the untreated group but not in the BMP-2 or β-gal groups. The femoral heads in the BMP-2 group had a normal density and surface, while those in the β-gal group presented with a low density and an irregular surface. Histologically, new bone and fibrous tissue were formed in the macropores of the β-TCP. Sixteen weeks after implantation, lamellar bone had formed in the BMP-2 group, but there were some empty cavities and residual fibrous tissue in the β-gal group. The new bone volume in the BMP-2 group was significantly higher than that in the β-gal group. The maximum compressive strength and Young’s modulus of the repaired tissue in the BMP-2 group were similar to those of normal bone and significantly higher than those in the β-gal group.

Our findings indicate that porous β-TCP loaded with BMP-2-gene-transduced BMSCs are capable of repairing early-stage, experimentally-induced osteonecrosis of the femoral head and of restoring its mechanical function.