An in vitro Experimental Insight into the Osteoblast Responses to Vitamin D3 and Its Metabolites.

BACKGROUND: 25-hydroxyvitamin D3 (25[OH]VD3) has recently been found to be an active hormone. Its biological actions are also demonstrated in various cell types. However, the precise influences of vitamin D3 (VD3) and its metabolites (25[OH]VD3, 1α,25-dihydroxyvitamin D3 [1α,25-(OH)2VD3]) on the osteoblast differentiation remain largely unknown. In this work, we investigated the effects of VD3 and its metabolites in different concentrations on the early and later osteoblast differentiation and biomineralization. METHODS: We first used quantitative real-time polymerase chain reaction (RT-qPCR) to evaluate the responsiveness of osteoblasts to VD3, 25(OH)VD3 or 1α,25-(OH)2VD3. We also evaluated the proliferation, differentiation and biomineralization of osteoblast at different time points via cell counting kit-8 assay and the analysis of osteogenic markers. RESULTS: The experimental results confirmed that osteoblasts could be responsive to 25(OH)VD3 and 1α,25-(OH)2VD3 but could not directly metabolize VD3 and 25(OH)VD3. Only 200 nmol/L VD3 significantly promoted osteoblast proliferation, while 25(OH)VD3 and 1α,25-(OH)2VD3 did not show obvious actions. Moreover, the early osteogenic markers were increased by 25(OH)VD3 and 1α,25-(OH)2VD3 in a dose-dependent manner. More importantly, only 25(OH)VD3 had accelerated the gene and protein expressions of osteocalcin and the biomineralization level of osteoblasts. CONCLUSIONS: Our findings provide reliable evidence that 25(OH)VD3 at 100-200 nmol/L can induce the early and later osteoblast differentiation and biomineralization for clinical bone tissue engineering.

Two-stage posterior-only procedures for correction of severe spinal deformities.

PURPOSE: To review the outcomes of surgical treatment for severe spinal deformities via a two-stage posterior-only approach. METHODS: A total of 18 patients with large and rigid spinal deformities were studied based on clinical and radiographic data. All of them received a two-stage posterior-only approach: first on the concave side by internal distraction of pedicle screws and rods through intramuscular tunnels, followed by respiratory function exercise and improving nutritional status during the intervening period, and finally by posterior additional correction, ultimate instrumentation and spinal fusion in the second operation. RESULTS: The mean major coronal curve was corrected by 46% after the first operation and by 60.4% after the second operation. The mean thoracic kyphosis was corrected by 50.9% after the first operation and by 64.8% after the second operation. The loss of correction mean was 3.3° for the major coronal curve and 2.6° for the thoracic kyphosis at a mean of 31.5 months follow-up. The mean operation time for the first and second operation was 186.2 and 300.6 min, and the mean intraoperative blood loss was 211.1 and 1,597.2 mL, respectively. No severe complication was noticed in this series. CONCLUSIONS: The two-stage posterior-only procedures permitting stepwise correction for the treatment of severe spinal deformities provide safe and satisfactory outcomes in this patient population.

[Analysis of neurological deficits complications in the treatment of spinal deformity with posterior spinal osteotomy].

OBJECTIVE: To investigate the incidence and causes of neurologic deficits complications in the treatment of spinal deformity with posterior spinal osteotomy. METHODS: From January 2007 to December 2010, 321 cases of scoliosis or kyphosis patients were treated with posterior spinal osteotomy. There were 124 male and 197 female with an average age of (19 ± 11) years (2 - 56 years). The average preoperative main Cobb angle was 108° ± 33° (48° - 175°), the average kyphotic angle was 74° ± 29° (53° - 170°) before operation. Pedicle subtraction osteotomy was used in 226 cases, 95 cases with vertebral column resection. Pedicle screw-rod system was used for fixation. The patients were monitored by Somatosensory-evoked potentials monitoring and Stagnara wake-up test. RESULTS: There were 11 cases with varying degrees of new neurologic deficits and the total incidence was 3.4%. The causes were as followed, spinal translation in 2 cases, compromised by close of resected areas in 2 cases, residual bone compression in 1 case, inadvertent operation in 2 cases, screw malposition in 1 case, hematoma compression in 1 case and spine elongation in 2 cases. There was significant difference between the patients with preexisting neurologic deficits (20.0%) and the patients with intact neurologic function (2.6%) (χ(2) = 13.060, P = 0.011), no significant differences in different classes of the age, etiology, deformity, osteotomy type and surgical type (P > 0.05). But the incidence of neurologic deficits was 4.6% in congenital scoliosis, 7.1% in neuromuscular scoliosis, 5.1% in kyphosis, 5.9% in adult deformity and 5.9% in Cobb angle more than 100°, which was higher than other classes. All the 11 cases were given emergent Methylprednisolone, neurotrophic drugs and hyperbaric oxygen therapy, 4 cases were underwent surgical exploration again. After treatment, 7 cases recovered completely, 2 cases recovered partially and 2 cases failed to improve at the last follow-up. CONCLUSIONS: Severe spinal deformity could be effectively treated with posterior spinal osteotomy. But the procedure is technical demanding and risky for neurologic deficits. The high risk factor is preexisting neurologic deficits.

[Clinical application of posterior paramedian approach in low back surgeries].

OBJECTIVE: To prospectively evaluate the clinical effects of posterior paramedian approach in nerve root decompression and reducing muscle damage in low back surgeries. METHODS: Study group included 30 cases treated from January 2007 to May 2008, DDD 8 cases, spondylolisthesis 6 cases, LDH 11 cases, Low back surgery failure re-operation 5 cases. Based on the comprehensive understanding of modern spine anatomy, we abandoned laminectomy in our procedure, applied a mid-waist skin incision, dissect to the paraspinal muscles where you could easily reach the facets by separating between the multifidus and longissimus, enlarge the canal by performing resection along ligamentum flavum and the inner broader of the articular process, remove enough tissue till you could expose the traversing root and the disc space, this method could achieve a limited but precise and effective decompression with not taking out all of the articular process. Once the anatomy mark of the pedicle is located (usually would be at the central area of the incision), pedicle screws placement would be precise and easy without struggling with muscle traction. The following procedures would be Spondylolisthesis reduction, discectomy and interbody fusion. RESULTS: Post-op patients of study group all showed significant improvement of pain symptoms, VAS reduced from 7.14 + or - 1.8, pre-op to 1.39 + or - 0.72 post-op, narrowed disc space regained height, spondylolisthesis reached anatomic reduction, no complications such as pedicle screw misplacement and nerve root damage were found, the lumbar spine regained it's physiological lordosis structure. Significant difference is discovered (P < 0.001) in statistic study concerning the rate of intractable low back pain between pre-op and post-op. CONCLUSIONS: Applying low back surgery through posterior para-median approach could directly reach the inferior/superior facets and the "soft" structures of the spinal canal, expose the exact decompression region and anatomy mark of the pedicle in the central surgical field without strong retraction on the para-spinal muscles. This approach has the advantage of lowering the surgical difficulty of implantation, reducing the risk of nerve damage and is also a minimum invasive procedure. In many cases, laminectomy is unnecessary, leaving the lamina intact could preserve the physiological anatomy of the spine.

Fifty top-cited spine articles from mainland China: A citation analysis.

Objective To identify the 50 top-cited spine articles from mainland China and to analyze their main characteristics. Methods Web of Science was used to identify the 50 top-cited spine articles from mainland China in 27 spine-related journals. The title, year of publication, number of citations, journal, anatomic focus, subspecialty, evidence level, city, institution and author were recorded. Results The top 50 articles had 29-122 citations and were published in 11 English-language journals; most (32) were published in the 2000s. The journal Spine had the largest number of articles and The Lancet had the highest impact factor. The lumber spine was the most discussed anatomic area (18). Degenerative spine disease was the most common subspecialty topic (22). Most articles were clinical studies (29); the others were basic research (21). Level IV was the most common evidence level (17). Conclusions This list indicates the most influential articles from mainland China in the global spine research community. Identification of these articles provides insights into the trends in spine care in mainland China and the historical contributions of researchers from mainland China to the international spine research field.

Posterior-only vertebral column resection for revision surgery in post-laminectomy rotokyphoscoliosis associated with late-onset paraplegia: A case report and literature review.

RATIONALE: Severe post-laminectomy spinal deformity associated with late-onset paraplegia is a complex and rare disorder. Little is known about revision surgery in post-laminectomy rotokyphoscoliosis associated with late-onset paraplegia treated by the single stage posterior-only vertebral column resection (VCR) procedure. PATIENT CONCERNS AND DIAGNOSES: The patient was a 14-year-old male diagnosed as post-laminectomy rotokyphoscoliosis associated with late-onset paraplegia. He underwent posterior total laminectomy through the thoracic spine for intramedullary spinal cord tumors at the age of 3 years in another hospital. He then developed kyphosis deformity 1 year after laminectomy, and underwent posterior spinal fusion without instrumentation at 9 years of age. However, the deformity gradually progressed over the years. Seven months before admission to our hospital, he developed a significant progression of neurological deficits, including weakness of strength and sensation in lower extremities bilaterally, with no bladder or bowel dysfunction. There was no improvement of spinal cord function with conservative measures, and he required a wheelchair for movement. INTERVENTIONS: The patient underwent posterior-only VCR by single stage with the purposes of spinal cord decompression and spinal deformity correction. OUTCOMES: Postoperatively, he was transferred to the intensive care unit (ICU) and required positive pressure ventilation support to improve his respiratory condition. The child experienced cerebrospinal fluid leak (CSF) which resulted in an unplanned return to the operating room. The neurological function improved from preoperative Frankel C to Frankel D within 12 months of surgery, and recovered completely to Frankel E by 18 months. At the 24 month follow-up, the good neurological function was maintained; pulmonary function tests (PFTs) revealed improved forced vital capacity (FVC) and forced expiratory volume for 1 second (FEV1). The patient's coronal major curve and sagittal kyphosis were corrected from 70° to 21°, and 170° to 75°, respectively. LESSONS: These findings demonstrated that single-stage posterior-only VCR is efficacious but challenging for revision surgery in post-laminectomy rotokyphoscoliosis associated with late-onset paraplegia.

Effect of Long-Term Simulated Microgravity on Immune System and Lung Tissues in Rhesus Macaque.

We evaluated different lymphocyte populations and levels of plasma cytokines in peripheral blood as well as inflammatory infiltration and expressions of cytokines in lung tissues derived from macaque under long-term stimulated microgravity through being suspended in an antiorthostatic position so as to identify relevant immune parameters and to understand potential mechanisms of lung injury. Fifteen healthy male rhesus macaques were randomly divided into groups 1 (control, n = 5), groups 2 (head-down tilting for 6 weeks, n = 5), and groups 3 (head-down tilting for 6 weeks and recovery for 4 weeks, n = 5). Lymphocyte subsets in peripheral blood were analyzed using flow cytometry and the concentrations of 14 cytokines in plasma were measured with Luminex multiplexing technology. HE staining and transmission electron microscopy were employed to investigate the morphologies and subcellular structures of lung tissues. Immunohistochemistry and real-time PCR were employed to explore mRNA and protein expressions of cytokines in lung tissues. Immunohistochemical demonstrations were detected for CD3, CD4, CD8 T lymphocytes, CD20 B lymphocytes, and CD68 macrophages in lung tissues. Compared to group 1, groups 2 and 3 showed a decrease in the percentage of CD2+T cells, CD2+CD4+T helper cells, and CD2+CD8+cytotoxic T cells as well as an increase in the expression of CD95 on the surface of T lymphocytes in peripheral blood. The serum cytokine levels of IL-18 and TNF-α were increased in group 2 when compared to groups 1 and 3. HE and TEM observed changes in the structure and ultrastructure of lung tissues in groups 2 and 3. The number of CD3+T cell, CD4+T cell, CD8+T cells, and CD68+macrophage and the expression levels of IL-1ß, IL-6, and IL-18 in lung tissues were increased in groups 2 when compared with groups 1 and 3. Our data suggested that long-term microgravity might alter the functions of immune system and cause lung damage, changing lymphocyte distribution and functions as well as cytokine production.

Balloon kyphoplasty: an experience of 38 patients with painful osteoporotic vertebral compressive fractures.

OBJECTIVE: To evaluate the efficacy and safety of percutaneous balloon kyphoplasty as a new therapy for patients with painful osteoporotic vertebral compressive fractures of the lumbar and thoracic spine. METHODS: A retrospective analysis was conducted in 38 consecutive patients (28 females, 10 males), whose ages ranged from 56 to 82 years (mean age 72 years). The symptom- and sign-positive spinal segment was identified by MRI. The time between onset of symptoms and surgical intervention ranged from 2 days to 1 year. 62 segments (36 thoracic, 26 lumbar) were treated in this cohort. The pain score estimated by Visual Analog Scale and activity degree were assessed immediately after operation and at 1-, 6-, and 12-month postoperative follow-up. Preoperative and postoperative anterior, midline vertebral heights in fractured vertebrae were measured on lateral radiographs to evaluate the effect of the procedure. RESULTS: The method achieved a swift pain relief associated with an evidently increased weight-bearing ability. The pain score was reduced from 8.2 to 2.4 points. The anterior and midline vertebral heights in 62 fractured vertebral bodies increased up to 82.76%+/-26.84%, 88.82%+/-21.75% and the wedge decreased from 15 to 8 degrees. This effect persisted at least over a period of two years. The procedure did not induce narrowing of the spinal canal and no severe complications occurred. CONCLUSIONS: Balloon kyphoplasty can result in immediate clinical improvement of mobility and pain relief, increase vertebral body height, and quickly return patient's activity. The short-term results are approved excellent, and the long-term results need further judgment.

Posterior Vertebral Column Resection for Severe and Rigid Spinal Deformity Associated With Neurological Deficit After Implant Removal Following Posterior Instrumented Fusion: A Case Report and Literature Review.

STUDY DESIGN: Case report. OBJECTIVE: To investigate the safety and efficacy of posterior vertebral column resection for severe and rigid spinal deformity associated with neurological deficit after implant removal following posterior instrumented fusion. SUMMARY OF BACKGROUND DATA: Loss of correction after implant removal in patients with posterior instrumented fusion has been previously reported. However, to our knowledge, posterior vertebral column resection (PVCR) for severe and rigid spinal deformity associated with neurological deficit after implant removal following posterior instrumented fusion has not been reported. METHODS: An 18-year-old female with severe and rigid spinal deformity associated with neurological deficit was classified as Frankel C, according to the Frankel grading system. She underwent posterior spinal fusion with pedicle screw fixation at 16 years, and her implants were removed after 1 year due to back pain. Seven months after removal of the implants, she began to experience weakness in her lower limbs but did not seek any treatment. She was unable to stand and had to use a wheelchair. The patient successfully underwent PVCR and posterior reinstrumentation. Within 3 months, her neurological status improved to Frankel E. RESULTS: The patient had no neurological deterioration and infections. There was no instrumentation failure and loosening correction at the 32 months follow-up. CONCLUSION: Our results suggest that PVCR and pedicle screw fixation is a safe and efficacious option for severe and rigid spinal deformity associated with neurological deficit after implant removal following posterior instrumented fusion. LEVEL OF EVIDENCE: N/A.

[Selection of surgical procedure for the treatment of idiopathic scoliosis].

OBJECTIVES: To discuss and evaluate the selection of surgical procedure for the treatment of idiopathic scoliosis according to the location and degree of the deformity. METHODS: 175 patients with idiopathic scoliosis underwent surgical treatment with correction and fusion. The patients were divided into four groups according to the location and degree of the deformity and four different procedures were used for each group. For each group, the blood loss, surgery time, correction rate, loss of correction at final follow up and complications were compared and analyzed. RESULTS: All patients underwent surgery safely and no neurological complication occurred. The correction rate was 81% for Group I, 86% for Group II, 68% for Group III and 72% for Group IV. All patients were followed up at least 2 years and the average time was 38 months (24 approximately 52). CONCLUSION: Proper selection of surgical procedure according to the location and degree of the scoliotic deformity, satisfactory results can be achieved in the treatment of idiopathic scoliosis.

In vivo measurements of patellar tracking and finite helical axis using a static magnetic resonance based methodology.

Patellofemoral (PF) maltracking is a critical factor predisposing to PF pain syndrome. Many novel techniques of measuring patellar tracking remain research tools. This study aimed to develop a method to measure the in vivo patellar tracking and finite helical axis (FHA) by using a static magnetic resonance (MR) based methodology. The geometrical models of PF joint at 0°, 45°, 60°, 90°, and 120° of knee flexion were developed from MR images. The approximate patellar tracking was derived from the discrete PF models with a spline interpolation algorithm. The patellar tracking was validated with the previous in vitro and in vivo experiments. The patellar FHA throughout knee flexion was calculated. In the present case, the FHA drew an "L-shaped" curve in the sagittal section. This methodology could advance the examination of PF kinematics in clinics, and may also provide preliminary knowledge on patellar FHA study.

The efficacy and cost-effectiveness of cell saver use in instrumented posterior correction and fusion surgery for scoliosis in school-aged children and adolescents.

Posterior spinal instrumentation and fusion surgery in school-aged children and adolescents is associated with the potential for massive intraoperative blood loss, which requires significant allogeneic blood transfusion. Until now, the intraoperative use of the cell saver has been extensively adopted; however, its efficacy and cost-effectiveness have not been well established. Therefore, the aim of this study is to determine the efficacy and cost-effectiveness of intraoperative cell saver use. This study was a single-center, retrospective study of 247 school-aged and adolescent patients who underwent posterior spinal instrumentation and fusion surgery between August 2007 and June 2013. A cell saver was used intraoperatively in 67 patients and was not used in 180 patients. Matched case-control pairs were selected using a propensity score to balance potential confounders in baseline characteristics. Allogeneic red blood cell (RBC) and plasma transfusions as well as blood transfusion costs were analyzed. The propensity score matching produced 60 matched pairs. Compared to the control group, the cell saver group had significantly fewer intraoperative allogeneic RBC transfusions (P = 0.012). However, when the combined postoperative and total perioperative periods were evaluated for the use of allogeneic RBC transfusion, no significant differences were observed between the two groups (P = 0.813 and P = 0.101, respectively). With regard to the total cost of perioperative transfusion of all blood products (RBC and plasma), costs for the control group were slightly lower than those of the cell saver group, but this variance did not reach statistical significance (P = 0.095). The use of the cell saver in posterior spinal instrumentation and fusion surgery in school-aged children and adolescents was able to decrease the amount of intraoperative allogeneic RBC transfusion but failed to decrease total perioperative allogeneic RBC transfusion. Moreover, the use of the cell saver was not cost-effective.

Surgical treatment of severe scoliosis and kyphoscoliosis by stages.

BACKGROUND: Although previous reports had reported the use of temporary internal distraction as an aid to correct severe scoliosis, two-stage surgery strategy (less invasive internal distraction followed by posterior correction and instrumentation) has never been reported in the treatment of patients with severe spinal deformity. This study aimed to report the results of the surgical treatment of severe scoliosis and kyphoscoliosis by two-stage and analyse the safety and efficacy of this surgical strategy in the treatment of severe spinal deformities. METHODS: A total of 15 patients with severe scoliosis, kyphoscoliosis or kyphosis who underwent two-stage surgeries (less invasive internal distraction followed by posterior correction and instrumentation) were studied based on hospital records. Pretreatment radiographs and radiographs taken after first surgery (internal distraction by two small incisions), before second surgery (posterior correction, instrumentation and fusion), one week after second surgery and final follow-up were measured. Subjects were analyzed by age, gender, major coronal curve magnitude, flexibility of major curve, major sagittal curve magnitude before first surgery, after first surgery, before second surgery, after second surgery and at final follow-up. Complications related to two-stage surgeries were noted in each case. RESULTS: The average major curve magnitude was 129.4° (range, 95° to 175°), reduced 58.9° or 45.4% after first stage surgery and reduced 30.6° or 24.6% after second stage surgery. The loss of correction during the interval between two surgeries was 7.1%. The total major coronal curve correction was 81.4° or 62.9%. At the final follow up, the average loss of correction of major coronal curve was 3.9° and the final average correction rate was 59.7%. The average major sagittal curve magnitude was 80.3° (range, 30° to 170°), and the total major sagittal curve correction was 48.2°. Loss of correction averaged 4.0° for major sagittal curve and the final correction averaged 42.2°. Clinical complications were noted in the peri-operative and long-term periods. CONCLUSIONS: Two-stage surgery was a safe and effective surgical strategy in this difficult population. Using two-small-incision technique, the first stage surgery was less invasive. No permanent neurologic deficit was noted in this series.

[Effectiveness comparison between pedicle subtraction osteotomy and non-osteotomy techniques in treatment of medium-to-severe kyphoscoliosis].

OBJECTIVE: To evaluate the effectiveness of pedicle subtraction osteotomy (PSO) and non-osteotomy techniques in treatment of medium-to-severe kyphoscoliosis by retrospective studies. METHODS: Between January 2005 and January 2009, 99 patients with medium-to-severe kyphoscoliosis were treated by PSO (PSO group, n = 46) and non-osteotomy technique (non-osteotomy group, n = 53) separately. There was no significant difference in sex, age, Cobb angle of scoliosis on coronal plane, and Cobb angle of kyphosis on saggital plane between 2 groups (P > 0.05). The operation time and blood loss were recorded; the Cobb angle of scoliosis on coronal plane and kyphosis on sagittal plane were measured at pre- and postoperation to caculate the rates of correction on both planes. RESULTS: The operation was successfully completed in all the patients. The operation time and blood loss of the patients in PSO group were significantly greater than those of the patients in non-osteotomy group (P < 0.05). All patients were followed up 12-56 months (mean, 22.4 months); no spinal cord injury occurred, and bone fusion was achieved at last follow-up. The Cobb angles of scoliosis and kyphosis at 2 weeks and last follow-up were significantly improved when compared with the preoperative angles in the patients of 2 groups (P < 0.05). There was no significant difference in Cobb angle of scoliosis and the rate of correction between 2 groups (P > 0.05), but the correction loss of PSO group was significantly smaller than that of non-osteotomy group (P < 0.05) at last follow-up. At 2 weeks and last follow-up, the Cobb angle of kyphosis, the rate of correction, and correction loss were significantly better in PSO group than in non-osteotomy group (P < 0.05). CONCLUSION: There is no signifcant difference in scoliosis correction between PSO and non-osteotomy techniques. PSO can get better corrective effect in kyphosis correction than non-osteotomy technique, but the operation time and blood loss would increase greatly.

[Correlative factors of secondary fracture after percutaneous kyphoplasty for osteoporotic vertebral compression fracture].

OBJECTIVE: To analyse the correlative factors of secondary vertebral fracture after percutaneous kyphoplasty (PKP) in treatment of osteoporotic vertebral compression fracture (OVCF) at different levels (adjacent and/or nonadjacent levels). METHODS: Between December 2002 and May 2008, 84 patients with OVCF were treated with PKP, and the clinical data were analysed retrospectively. There were 11 males and 73 females with an average age of 70.1 years (range, 55-90 years). All patients were followed up 24-96 months (mean, 38 months). Secondary vertebral fracture occurred in 12 cases at 3-52 months after PKP (secondary fracture group), no secondary fracture in 72 cases (control group) at over 24 months. The preoperative bone mineral density, postoperative vertebral height compression rate, postoperative Cobb angle, amount of injected bone cement per vertebra, puncture pathway (uni- or bilateral puncture), age, gender, number of fracture segment, and cement intradiscal leakage were compared between 2 groups to find correlative factors of secondary vertebral fractures. RESULTS: There was no significant difference in preoperative bone mineral density, postoperative vertebral height compression rate, postoperative Cobb angle, amount of injected bone cement per vertebra, puncture pathway, age, gender, and number of fracture segment between 2 groups (P > 0.05). But the incidence of cement intradiscal leakage was much higher in secondary fracture group than in control group (chi2 = 5.294, P = 0.032). CONCLUSION: Cement intradiscal leakage may be the correlative factor of secondary vertebral fracture after PKP in OVCF.

[Balloon inflating and cement filling for treatment of avascular necrosis of the femoral head: a three-dimensional infinite-element study].

OBJECTIVE: To evaluate the biomechanical changes of balloon inflating and cement filling in avascular necrosis of the femoral head using finite-element analysis. METHODS: The procedure of percutaneous balloon inflating and cement filling was simulated in fresh specimen of human femoral head. CT scan and three-dimensional reconstruction were used to establish the three-dimensional model of the femoral head. The physiological load was analyzed using three-dimensional finite element model to simulate the load and calculate stress on the hip during walking. Finite element analysis was performed on the avascular necrosis model and balloon inflating and bone cement filling model to measure the Von-Mises force at the top, neck and weight-bearing area of the femoral head. Another 8 fresh specimens of femoral head necrosis of human were obtained to stimulate balloon inflating and bone cement filling procedures, and the displacement of the femoral head under different loads was recorded before and after the procedures. RESULTS: After bone cement filling in the necrosis area, the load reduced significantly in the weight-bearing area of the femoral head, and the load distribution became more uniform at the femoral neck and the top of the head. The anti-deformation ability of the necrosis femoral head increased after bone cement filling. The infinite-element analysis and specimen biomedical test showed similar results. CONCLUSION: Percutaneous balloon inflating and bone cement filling in the necrosis area can change the biomechanics mechanism of the femoral head and neck, improve the supporting capacity under load, and prevent the progression of head collapse.

[Experimental study of novel injectable nucleus pulposus prostheses implant].

OBJECTIVE: To explore the histological and the hematological change of rabbits after implanting novel injectable artificial nucleus prostheses, and to evaluate the biological safety. METHODS: In accordance with Biological Evaluation of Medical Devices, materials of polyurethane, silicone rubber and macromolecular polyethylene for medical use were made into short column 1 cm in length and 0.3 cm in diameter. Forty-eight SPF New Zealand white rabbits weighing 2.5-3.0 kg were used, and cavity 1 cm in depth was made in the area 2 cm away from the spinal midline by separating muscle. Then according to different material being implanted, the rabbits were divided into 3 groups (n = 16): Group A, polyurethane; group B, silicone rubber; group C, macromolecular polyethylene for medical use as negative control. General condition of the rabbits was observed after operation. Gross and histology observation were conducted 1, 4, 12 and 26 weeks after operation. Blood routine, biochemical function and electrolyte assays were performed 26 weeks after operation to observe pathological changes of organs. Meanwhile, physicochemical properties of the materials were detected, and the material in the same batch was used as negative control. RESULTS: All rabbits survived until the end of experiment, and all wounds healed by first intention. In each group, red swollen muscles were observed 1 week after operation and disappeared 4 weeks after operation, connective tissue around the implanted materials occurred 12 and 26 weeks after operation. At 26 weeks after operation, there were no significant differences among three groups in blood routine, biochemical function and electrolyte assays (P > 0.05). Organs had smooth surface without ulceration, ecchymosis, obvious swelling, hyperemia or bleeding, and nodules. There were no significant differences among three groups in percentage weight of each organ (P > 0.05). Histology observation: granulation tissue proliferation and inflammatory cell infiltration were observed in each group 1 week after operation, fibrous capsule formation around the materials and the disappearance of inflammatory cell infiltration were evident 4 weeks after operation, cyst wall grew over time and achieved stability 12 weeks after operation. The inflammatory response and the fiber cyst cavity of groups A and B met the standard of GB/T 16175 and were in line with group C. No specific pathological changes were discovered in the organs 26 weeks after operation. For group A, no significant difference was evident between before and after material implantation in terms of weight average molecular weight, number average molecular weight, tensile strength at break and elongation at break (P > 0.05). For group B, no significant difference was evident between before and after material implantation in shore hardness (P > 0.05). CONCLUSION: Novel injectable nucleus pulposus prostheses do not damage local tissue and function of organs, but provide good biocompatibility and biological safety.