Biomaterial-loaded allograft threaded cage for the treatment of femoral head osteonecrosis in a goat model

Bone tissue engineering for treating osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a devastating and complicated disease with an unclear etiology. Femoral head-preserving surgeries have been devoted to delaying and hindering the collapse of the femoral head since their introduction in the last century. However, the isolated femoral head-preserving surgeries cannot prevent the natural progression of ONFH, and the combination of autogenous or allogeneic bone grafting often leads to many undesired complications. To tackle this dilemma, bone tissue engineering has been widely developed to compensate for the deficiencies of these surgeries. During the last decades, great progress has been made in ingenious bone tissue engineering for ONFH treatment. Herein, we comprehensively summarize the state-of-the-art progress made in bone tissue engineering for ONFH treatment. The definition, classification, etiology, diagnosis, and current treatments of ONFH are first described. Then, the recent progress in the development of various bone-repairing biomaterials, including bioceramics, natural polymers, synthetic polymers, and metals, for treating ONFH is presented. Thereafter, regenerative therapies for ONFH treatment are also discussed. Finally, we give some personal insights on the current challenges of these therapeutic strategies in the clinic and the future development of bone tissue engineering for ONFH treatment.

A 3D Printed Porous Titanium Alloy Rod with Diamond Crystal Lattice for Treatment of the Early-Stage Femoral Head Osteonecrosis in Sheep

Instruments made of porous titanium alloy and fabricated with a 3D printed technique are increasingly used in experimental and clinical research. To date, however, few studies have assessed their use in early-stage osteonecrosis of the femoral head (ONFH). In this study, porous titanium alloy rods (Ti-Rod) with diamond crystal lattice, fabricated using an electron beam melting (EBM) technique, were implanted into sheep models (n=9) of early-stage ONFH for 6 months. Bone ingrowth and integration were investigated and compared with those of sheep (n=9) undergoing core decompression (CD) alone. Following Ti-Rod implantation, femoral heads showed fine osteointegration, with X-ray evaluation showing compact integration between peripheral bone and rods without radiolucent lines encircling the rods, as well as new bone growth along the metal trabeculae without the intervention of fibrous tissue. The regions of interest (ROIs) of femoral heads showed fine bone ingrowth after Ti-Rod implantation than CD alone. By micro-CT evaluation, the ratios of bone volume to total volume (BV/TV) of ROIs in Rod group was 930 % and 452 % higher than CD group after 3 (0.206 ± 0.0095 vs. 0.020 ± 0.0058, p < 0.05, n=3) and 6 (0.232 ± 0.0161 vs. 0.042 ± 0.0061, p < 0.05, n=3) months respectively. By histological evaluation, the BV/TV of ROIs in Rod group was 647 % and 422 % higher than CD group after 3 (0.157 ± 0.0061 vs. 0.021 ± 0.0061, p < 0.05, n=3) and 6 (0.235 ± 0.0145 vs. 0.045 ± 0.0059, p < 0.05, n=3) months respectively. The new bone grew along metal trabeculae into the center of the rod with a rapid bone ingrowth in Rod gorup. Whereas in CD group, new bone grew mainly at the periphery of the decompressive channel with a slow bone ingrowth. Mechanical analysis showed that maximum load on the femoral head-necks was 31 % greater 6 months after Ti-Rod implantation than after CD alone when the vertical press reached the apex (3751.75 ± 391.96 vs. 2858.25 ± 512.91 N, p < 0.05, n=3). The association of rod implantation with fine bone ingrowth, osteointegration, and favorable mechanical properties suggests that implantation of the porous titanium alloy rod with the diamond crystal lattice may be a beneficial intervention for patients with early-stage ONFH.

Development of an animal fracture model for evaluation of cement augmentation femoroplasty: an in vitro biomechanical study

Osteoporotic hip fracture is the most severe kind of fracture with high morbidity and mortality. Patients' ambulation and quality of life are significantly affected by the fracture because only 50% regain their prefracture functional status, even if they undergo surgeries. There are many issues associated with the current preventive methods e.g., cost, side effects, patient compliance, and time for onset of action. Femoroplasty, the injection of bone cement into the proximal femur to augment femoral strength and to prevent fracture, has been an option with great potential. However, until now femoroplasty has remained at the stage of biomechanical testing. No in vivo study has evaluated its safety and effectiveness; there is not even an animal model for such investigations. The objective of this study was to develop a proximal femur fracture goat model that consistently fractures at the proximal femur when subject to vertical load, simulating osteoporotic hip fractures in human. Six pairs of fresh frozen mature Chinese goats' femora were obtained and randomly assigned into two groups. For the experimental group, a cylindrical bone defect was created at the proximal femur, while the control was left untreated. In addition, a configuration to mimic the mechanical axis of the goat femur was developed. When subjected to load along the mechanical axis, all the specimens from the bone defect group experienced femoral neck fractures, while fractures occurred at the femoral neck or other sites of the proximal femur in the control group. The biomechanical property (failure load) of the bone defect specimens was significantly lower than that of the control specimens (p<0.05). Osteoporotic hip fractures of humans were simulated by a goat fracture model, which may serve as a reference for future femoroplasty studies in vivo. The newly developed configuration simulating a femoral mechanical axis for biomechanical tests was practicable during the study.

Treatment of femoral head osteonecrosis with advanced cell therapy in sheep

BACKGROUND

The purpose of this study was to evaluate the efficacy of core decompression associated with advanced cell therapy for the treatment of femoral head osteonecrosis in an established sheep model.

METHODS

Early stage osteonecrosis of the right hip was induced cryogenically in 15 mature sheep. At 6 weeks, the sheep were divided into three groups, Group A: core decompression only; Group B: core decompression followed by implantation of an acellular bone matrix scaffold; Group C: core decompression followed by implantation of a cultured BMSC loaded bone matrix scaffold. At 12 weeks, MRI hip studies were performed and then the proximal femur was harvested for histological analysis.

RESULTS

In the group of advanced cell therapy, Group C, there was a tendency to higher values of the relative surface of newly formed bone with a mean of 20.3 versus 11.27 % in Group A and 13.04 % in Group B but it was not statistically significant. However, the mean relative volume of immature osteoid was 8.6 % in Group A, 14.97 in Group B, and 53.49 % in Group C (p < 0.05), revealing a greater capacity of osteoid production in the sheep treated with BMSCs. MRI findings were not conclusive due to constant bone edema artifact in all cases.

CONCLUSIONS

Our findings indicate that a BMCSs loaded bone matrix scaffold is capable of stimulating bone regeneration more effectively than isolated core decompression or in association with an acellular scaffold in a preclinical femoral head osteonecrosis model in sheep.

Clinical result of structural augmentation with cannulated bone screws for the treatment of osteonecrosis of the femoral head

OBJECTIVE

To evaluate the results of treatment of osteonecrosis of the femoral head by structural augmentation through a routine core decompression procedure combined with insertion of cannulated bone screws incorporating autogenous bone graft and biomaterial containing decalcified bone matrix.

METHODS

From February 2002 to February 2005, 31 patients (33 hips) with femoral head necrosis were treated in our hospital using insertion of cannulated bone screws incorporating autogenous bone graft. There were 18 men and 13 women with an average age of 37 years (range, 27-49). The Steinberg classification was stage I for 20 hips (61%) and stage II for 13 hips (39%). Clinical and radiographic evaluations were performed on all patients. The patient's satisfaction was also assessed.

RESULTS

All 31 patients (33 hips) were retrospectively studied after a mean follow-up of 38 months (range, 18-48). The average Harris hip score was 76 before surgery and 91 at the final follow-up. All patients stated that they were satisfied and had significantly reduced pain. According to the Harris hip score system, 21 cases were excellent, 8 good and 2 fair. No complications, such as wound infection, subtrochanteric fracture, neuropathy and deep vein thrombosis, were found.

CONCLUSION

Structural augmentation using the insertion of cannulated bone screws incorporating autogenous bone graft is an effective option for Steinberg I-II stages of femoral head necrosis. Further study is needed to confirm mid- and long-term results.

Effect of vascular endothelial growth factor 121 adenovirus transduction in rabbit model of femur head necrosis

BACKGROUND

Our objective was to observe the role of vascular endothelial growth factor (VEGF) 121 gene transfer in promoting vascular reconstruction and bone repair in femur head necrosis of rabbits.

METHODS

The femoral head necrosis model was induced by injection with ethanol. The necrotic femoral head was transfected with a human adenoviral vector expressing VEGF (Ad-hVEGF121). Bone formation in the subchondral necrotic region was analyzed using histology, by measuring the bone mineral density value, and by observing bone trabecular morphology using image analysis.

RESULTS

Revascularization level, bone formation rate, bone quality and quantity, and mineralization level in the subchondral necrotic region of the gene transfection group were significantly higher than the control groups. The control groups had more subchondral bone resorption compared with the gene transfection group.

CONCLUSION

VEGF might promote bone formation and revascularization in the subchondral necrotic region of the femoral head, indirectly protecting the necrotic bone trabecula from absorption and avoiding a reduction in the mechanical function of the subchondral region.

Traumatic and Non-traumatic Osteonecrosis in the Femoral Head of a Rabbit Model

Osteonecrosis of the femoral head is an idiopathic, debilitating and progressive disease. A number of traumatic or non-traumatic animal models have been reported for research on osteonecrosis. This study was performed to compare the efficacy of femoral head osteonecrosis in rabbits by traumatic and non-traumatic methods. Twenty-seven New Zealand White rabbits were divided into three experimental groups, nine heads each. Two groups were surgically induced into osteonecrosis; a steel cerclage wire was ligated tightly around the neck of the right femoral head (Group W), and the femoral neck was tied with a cerclage wire in the same way as in the W group, and burned by attachment of an electrode tip to the wire and then the wire was removed (Group B). The other group was induced into osteonecrosis with a single intra-muscular injection of 20 mg/kg methyl-prednisolone acetate single injection (Group M). In the control group, the left femoral head of animals in group W and B was used. After two weeks, rabbits were sacrificed and the femoral head and neck were collected. Osteonecrosis of the femoral head was evaluated by radiography, histology and immunohistology methods. Osteonecrosis lesions in the femoral head were identified in traumatic models of groups W and B. Cartilage degeneration in the superficial layer and TUNEL positive cells in the femoral head were detected more in Group B than in Group W. These findings revealed that short-term induced osteonecrosis of the femoral head was effectively achieved by cautery around the femoral neck.

Structural augmentation with biomaterial-loaded allograft threaded cage for the treatment of femoral head osteonecrosis

Seventy-six patients with femoral head necrosis were allocated to a program of either core decompression (control group) or core decompression and implantation of a biomaterial-loaded allograft threaded cage (treatment group). All patients were followed up prospectively clinically and radiographically. In the control group, no significant improvement in Harris hip score was found, and 13 of the 22 hips had deteriorated to stage III. In the treatment group, the mean Harris hip score was improved from 62.8 to 81.6; the clinical success rate at 36 months postoperatively was 91%. Collapse was seen in 1 hip, and another 3 hips exhibited progressive collapse. The procedure is attractive as a minimally invasive and salvage procedure, which shows encouraging success rates and early clinical results in patients with Steinberg stage I-II osteonecrosis.