Biomechanical tests and finite element analyses of pelvic stability using bilateral single iliac screws with different channels in lumbo-iliac fixation.

Background: In lumbo-iliac fixation, the iliac screw can be placed in several locations and directions. There is no uniform standard for the placement of a single iliac screw. Biomechanical tests and finite element analyses were used to compare the effect of bilateral single iliac screws with three channels on pelvic stability to determine the best channel. Methods: Five embalmed adult cadaver pelvic specimens were selected. An unstable Tile C1 pelvic injury model was established. Lumbo-iliac fixation for the treatment of left sacral Denis II fracture includes the following: three channels of bilateral, single iliac screws (channel A from posterior superior iliac spine (PSIS) to anterior inferior iliac spine (AIIS), channel B from 1 cm medial and 1 cm caudal of PSIS to AIIS, and channel C from 2 cm below PSIS to AIIS). Biomechanical testing was performed for stiffness evaluations. A finite element model was established to study the stress distribution of the model and the maximum von Mises stress of internal fixation. Results: Biomechanical tests revealed that under vertical compression loading. The compressive stiffness fixed by channel B (246.15 ± 27.85 N/mm) was better than that fixed by channel A and channel C. Under torsional load, the torsional stiffness fixed by channel B (2.234 ± 0.223 N·m/°) was stronger than that fixed by channel A and channel C. However, there was no significant difference in terms of compressive and torsional stiffness between channel B and channel A (P > 0.05). Finite element analyses conformed that the maximum von Mises stress of the internal fixator fixed in channel B under the conditions of vertical, forwards bending, backwards extension, left bending, left rotating, and right bending (213.98 MPa, 338.96 MPa, 100.63 MPa, 297.06 MPa, 200.95 MPa and 284.75 MPa, respectively) was significantly lower than those fixed in channel A and channel C. Conclusions: The construct stiffness of the channel from 1 cm medial and 1 cm caudal of PSIS to AIIS is better than that of the other two channels. This channel has the advantages of good biomechanical stability, small maximum von Mises stress of internal fixation.

Enalapril inhibits inflammatory osteolysis induced by wear debris in a mouse model.

OBJECTIVE: Aseptic loosening, the most frequent complication after total joint replacement, is probably caused by an inflammatory response to the shedding of wear debris from the implant. The only effective treatment is surgical revision. Using a mouse model, we investigated whether enalapril inhibits wear debris-induced inflammatory osteolysis. METHODS: Titanium (Ti) alloy particles were introduced, and calvarial bone from syngeneic mice was implanted into air pouches established in BALB/c mice. Histological and molecular analyses were performed with inflammatory tissue samples obtained from mice treated with and without enalapril. RESULTS: Enalapril inhibited tissue inflammation and inflammatory osteolysis induced by Ti particles, reducing pouch membrane thickness and decreasing inflammatory cell infiltration. In addition, enalapril inhibited the expression of the inflammatory cytokines vascular endothelial growth factor and tumor necrosis factor-α. CONCLUSIONS: Our study provides evidence that enalapril inhibits Ti particle-induced inflammatory osteolysis, and it may be a potentially useful treatment for aseptic loosening.

The efficacy and safety of extracorporeal shockwave therapy in knee osteoarthritis: A systematic review and meta-analysis.

BACKGROUND: Extracorporeal shockwave therapy (ESWT) has been widely applied for pain control in musculoskeletal disorders. Whether ESWT can improve pain relief and joint function for knee osteoarthritis remains controversial. Therefore, we designed a meta-analysis based on relevant studies to comprehensively analyze and determine the efficacy and safety of ESWT for knee osteoarthritis. METHODS: We identified relevant studies by an electronic search consisting of five English language databases: MEDLINE (1966 to July 2019), the Cochrane Central Register of Controlled Trials (2019 Issue 2), EMBASE (1980 to July 2019), and PubMed (1946 to July 2019). The methodological quality of randomized controlled trials (RCTs) was independently evaluated by two reviewers according to the criteria in the Cochrane Collaboration for Systematic Reviews. The quality of cohort and case-control studies was assessed by the Newcastlee-Ottawa scale (NOS). We performed statistical analysis by the Stata software, version 15. RESULTS: Three RCTs and three cohort studies involving 589 patients were included. The present meta-analysis indicated that ESWT was associated a significant reduction of pain score at 4 weeks (WMD = -0.436; 95% CI = -0.604 to -0.269), 8 weeks (WMD = -0.234; 95% CI = -0.447 to -0.022) and 12 weeks (WMD = -0.239; 95% CI = -0.436 to -0.043). There were significant differences between the two groups in terms of the Western Ontario and McMaster Universities Osteoarthritis Index at 4 weeks (WMD = -3.107; 95% CI = -5.073 to -1.142), 8 weeks (WMD = -3.617; 95% CI = -5.760 to -1.475) and 12 weeks (WMD = -2.271; 95% CI = -3.875 to -0.667). CONCLUSION: The ESWT was efficacious and safe for reducing pain and improving knee function in patients with knee osteoarthritis, without increasing the risk of adverse effects.

Extraperiosteal segmental excision for osteofibrous dysplasia of tibia with reconstruction by liquid nitrogen-treated recycled autograft.

BACKGROUND: Osteofibrous dysplasia usually progresses until ten years of age and occasionally regresses spontaneously after puberty. Patients with osteofibrous dysplasia usually require close observation. Surgery is an option considered only for extensive, deforming lesions and those with pathological fractures and rapid progression prior to puberty. If surgery is indicated, the traditional intra-lesional curettage or subperiosteal resection usually leads to high recurrence. Hence, extraperiosteal wide excision and various methods of reconstruction after resection have been advocated for this lesion. We reviewed the clinical results of patients managed with extraperiosteal segmental excision and reconstruction by liquid nitrogen-treated tumor-bearing autograft combined with allograft. METHODS: From January 2010 to December 2014, twelve patients with final diagnosis of tibial osteofibrous dysplasia were studied retrospectively. All these patients were treated with extraperiosteal segmental excision and reconstruction by liquid nitrogen-treated tumor-bearing autograft combined with allograft. RESULTS: The patient group consisted of 5 males and 7 females, with a median age of 13 years (6-24 years). 3 lesions were located in left tibia and 9 in right. The median length of resected segment was 8 cm (5-11 cm). The patients were followed for 36-84 months (median 52 months). Follow-up radiographs showed that the median time for complete union of the grafted bone was 9 months (6-15 months). There was no evidence of recurrence. All patients had full range of motion in the knee and ankle joints after surgery. CONCLUSIONS: Extraperiosteal segmental excision for osteofibrous dysplasia of tibia with reconstruction by liquid nitrogen-treated recycled autograft and allograft is a good surgical option to prevent recurrence and fill bone defects in this rare lesion.

Inositol polyphosphate-4-phosphatase type II and rucaparib treatment inhibit the growth of osteosarcoma cells dependent on phosphoinositide 3-kinase/protein kinase B pathway.

Osteosarcoma (OS) is an aggressive malignant tumor of bone, which often occurs in children and adolescents. Currently, the effective method for the treatment of OS is still limited. The study aimed to investigate the synergistic antitumor effect of inositol polyphosphate-4-phosphatase, type-II (INPP4B) and rucaparib on OS cells. The expression levels of INPP4B in OS tissues and OS cell lines were examined by quantitative real-time polymerase chain reaction and Western blot analysis. SaOS2 and U2OS cells were then transfected with overexpression vector of INPP4B or were treated with different concentrations of rucaparib, and cell viability, cell cycle, and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry. Western blot assay uncovered the combined effects of INPP4B and rucaparib on cell cycle, apoptosis and phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signal pathway. Further, the tumor formation was examined in vivo. Results showed that INPP4B was low expressed in OS tissues and in OS cell lines. INPP4B overexpression significantly decreased cell viability and induced apoptosis in SaOS2 and U2OS cells. Additionally, rucaparib remarkably reduced cell viability in a dose-dependent and time-dependent manner. Meanwhile, rucaparib suppressed cell cycle progression in the S phase and promoted apoptosis in a dose-dependent manner. Further, combination of INPP4B overexpression and rucaparib declined Myc, cyclin E1 and cyclin D1 expressions, enhanced Bad, Bax, and cleaved-caspase-3 expressions, and blocked PI3K/AKT signal pathway in SaOS2 and U2OS cells. Finally, combination of INPP4B overexpression and rucaparib inhibited tumor formation in vivo. The study demonstrated that INPP4B and rucaparib exhibited synergistic antitumor effect by regulating PI3K/AKT pathway in OS cells.

[ANALYSIS OF IMPLANT-RELATED COMPLICATIONS AFTER HINGE KNEE REPLACEMENT FOR TUMORS AROUND THE KNEE].

OBJECTIVE: To investigate the reasons and managements of implant-related complications after hinge knee replacement for tumors around the knee. METHODS: A retrospective analysis was made on the clinical data of 96 patients undergoing hinge knee replacement between January 2000 and December 2012. There were 64 males and 32 females with the mean age of 31.0 years (range, 15-72 years). The most common tumor type was osteosarcoma (72 cases), and the second was giant cell tumor (15 cases). The tumor located at the distal femurs in 52 cases and at the proximal tibias in 44 cases. Fifteen hinge and 81 rotating hinge prostheses were used. The recurrence, metastasis, and survival were recorded. The implant-related complications were observed. RESULTS: The median follow-up time was 43.5 months (range, 10-156 months). Complications were observed in 21 patients (25 implant-related complications); 13 complications located at the femur and 12 complications at the tibia. The complications included aseptic loosening (8 cases), deep infection (7 cases), prosthetic breakage (4 cases), peri-prosthetic fracture (2 cases), and dislocation (4 cases). Most deep infection occurred within 12 months after operation (6/7), and most aseptic loosening after 40 months of operation (6/8). The rate of limb salvage was 90.6% (87/96) and the amputation rate was 9.4% (9/96). The overall survival rate of the prosthesis was 76.7% (5-year) and 47.2% (10-year). The 5-year survival rate was 82.9% for femoral prosthesis and 71.0% for tibial prosthesis, showing no significant difference (P = 0.954). CONCLUSION: Hinge knee prosthesis still has a high rate of complications. Deep infection is main reason to decrease short-term prosthetic survival rate, and aseptic loosening shortens the long-short prosthetic survival time.

[Experimental study on avascular necrosis of femoral head induced by methylprednisolone combined with lipopolysaccharide in rabbits].

OBJECTIVE: To establish a stable animal model for glucocorticoid-induced avascular necrosis of femoral head in rabbits. METHODS: Thirty-six adult New Zealand rabbits were randomly divided into four groups: ten were injected twice with lipopolysaccharide (group A), ten were treated with a combination of lipopolysaccharide and methylprednisolone (group B), ten were injected three times with methylprednisolone (group C), and six were injected normal saline as a control (group D). MR imaging was performed in the rabbits before the first injection of lipopolysaccharide or methylprednisolone, and at 2, 4, and 6 weeks after the last injection of lipopolysaccharide or methylprednisolone. Histopathological changes in the femoral heads were observed by light microscope and transmission electron microscope at the end of six weeks after the injection. Vascular infusion with Chinese ink was made to evaluate the morphological changes of blood vessels in the femoral head. The percentage of trabecular bone area and empty lacunae and microvascular density were measured. According to the histological and MR imaging appearance of the femoral heads in all groups, the incidence of osteonecrosis of every group was calculated. RESULTS: Listlessness, blepharal hyperemia, less activity and reduced diet were found in the rabbits of groups A and B after injected with lipopolysaccharide. At 3 weeks after the final injection, the body weight of groups B and C was decreased. At 4 weeks after the final injection, the body weight of groups A and D was increased. No abnormal signal could be detected on MR images in rabbits of all groups before injection and at 2 weeks after the injection. At 4 weeks and 6 weeks after the last injection, irregular low signal on T1-weighted images and irregular low or highsignal on T2-weighted images could be detected on MR images in rabbits of groups B and C, no abnormal signal could be detected on MR images in rabbits of groups A and D. At 6 weeks after the last injection, the trabecular bone of group B became thin and sparse, some were broken. The percentages of empty lacunae were 11.8% +/- 4.7%, 34.4% +/- 6.2%, 20.0% +/- 4.7% and 9.3% +/- 4.6%; the percentages of trabecular bone area were 59.2% +/- 6.8%, 40.1% +/- 6.0%, 51.5% +/- 5.6% and 63.2% +/- 8.3%; and the microvascular densities were 14.3% +/- 2.7%, 4.5% +/- 2.1%, 10.2% +/- 3.1% and 15.4% +/- 4.1% in groups A, B, C and D respectively. There were statistically significant differences between group B and groups A, C, D (P <0.01). The fatty tamponade accumulated in the medullary cavity and intramedullary vascular sinusoids were pressed by the lipocytes and became narrow. Limposomes were found in osteocytes and vascular endothelia of group B and group C. Osteocytes of group B crimpled and pyknosis or karyolysis of chromatin were observed in these osteocytes, nuclear membrane of the osteocytes was discontinous. Vascular endothelia became swollen and the cell junctions widened or were destroyed in groups A and B. The incidence of osteonecrosis in group B (88.9%) was higher than that in group C (22.2%, P < 0.05). There was no osteonecrosis occurred in groups A and D. Conclusion Methylprednisolone combined with lipopolysaccharide can induce typical rabbit model for early avascular necrosis of femoral head.

Upregulation of VEGF in subchondral bone of necrotic femoral heads in rabbits with use of extracorporeal shock waves.

Extracorporeal shock wave treatment appears to be effective in patients with avascular necrosis of the femoral head. However, the pathway of biological events whereby this is accomplished has not been fully elucidated. The purpose of this study was to investigate the effect of extracorporeal shock waves on vascular endothelial growth factor (VEGF) expression in necrotic femoral heads of rabbits. VEGF expression was assessed by immunohistochemistry, quantitative real-time PCR, and Western blot analysis. The degree of angiogenesis was also assessed, as determined by the microvessel density (MVD), the assessment of which was based on CD31-expressing vessels. Bilateral avascular necrosis of femoral heads was induced with methylprednisolone and lipopolysaccharide in 30 New Zealand rabbits. The left limb (the study side) received shock wave therapy to the femoral head. The right limb (the control side) received no shock wave therapy. Biopsies of the femoral heads were performed at 1, 2, 4, 8, and 12 weeks. Western blot analysis and real-time PCR showed that shock wave therapy significantly increased VEGF protein and mRNA expression, respectively, in the subchondral bone of the treated necrotic femoral heads. Compared with the contralateral control without shock wave treatment, the VEGF mRNA expression levels increased to a peak at 2 weeks after the shock wave treatment and remained high for 8 weeks, then declined at 12 weeks, whereas the VEGF protein expression levels increased to a peak at 4 weeks after the shock wave treatment and remained high for 12 weeks. The immunostaining of VEGF was weak in the control group, and the immunoreactivity level in the shock-wave-treated group increased at 4 weeks and persisted for 12 weeks. The most intensive VEGF immunoreactivity was observed in the proliferative zone above the necrotic zone. At 4, 8, and 12 weeks after the shock wave treatment, MVD in subchondral bone from treated femoral heads was significantly higher than that in subchondral bone from untreated femoral heads. These data clearly show that extracorporeal shock waves can significantly upregulate the expression of VEGF. The upregulation of VEGF may play a role in inducing the ingrowth of neovascularization and in improving the blood supply to the femoral head.