Nickel-titanium shape-memory sawtooth-arm embracing fixator for periprosthetic femoral fractures.

PURPOSE: We reviewed data to determine outcomes for 21 consecutive Vancouver type B1 or type C periprosthetic fractures that we treated between 2001 and 2008 using a nickel-titanium shape-memory sawtooth-arm embracing fixator. METHODS: The study participants were 12 men and 9 women (mean age, 70.8 years; range, 42-85 years). The average duration of follow-up monitoring was 39.7 months (range, 1-78 months). In five cases, cables and screws were used for further stabilisation. No bone grafting was performed for any of the patients. RESULTS: Results were satisfactory, except for one patient who died one month after surgery from a cause unrelated to arthroplasty. Bone union was achieved in the remaining 20 cases within an average of 5.25 months. No implant failures or malunions occurred in any of the patients. The average Harris hip score at the final follow-up examination was 79.3 points. CONCLUSIONS: Our results show that the embracing fixator is a valid alternative treatment for Vancouver type B1 or type C periprosthetic femoral fractures.

Evaluation of the zein/inorganics composite on biocompatibility and osteoblastic differentiation.

We have previously studied the biocompatibility and mechanical properties of porous zein scaffolds. We based the study on the concept that composite scaffold materials, especially when combined with inorganic materials, are more suited to the mechanical and physiological demands of the host tissue than individual scaffold materials. We investigated the effect of zein/inorganic composite on the physical and biological properties of porous zein scaffolds, which were fabricated by salt-leaching. The composite was prepared by immersion in simulated body fluid. The hydroxyapatite (HA)-coated zein scaffold had the same porosity as the zein scaffold (over 75%). Using scanning electron microscopy, it was established that the morphology of pores located on the surface and within the porous scaffolds showed equally good pore interconnectivity with zein. However, the compressive Young's modulus decreased from 240.1+/-96.8 to 34.4+/-12.6MPa, and compressive strength decreased from 7.8+/-1.2 to 4.2+/-0.8MPa. From the in vitro test with human bone marrow stroma cells, the osteoblastic differentiation on the surface of the HA-coated zein scaffold was increased, as expressed by the alkaline phosphatase activity and reverse transcription-polymerase chain reaction analysis for marker genes. From both the mechanical and biological evaluations, the HA-coated zein scaffold was found to be the optimal biomaterial for bone tissue engineering.

[Clinical study of lumbar fusion by hybrid construct of stem cells technique and biodegradable material].

OBJECTIVE: To explorer the effectiveness of enriched bone marrow stem cells technique for lumbar fusion. METHODS: With the randomization and control principles, 2 graft materials [Enrichment bone marrow mesenchymal stem cells hybridized with beta-tri calcium phosphate (composite graft group), autologous iliac crest bone graft (autograft group)] were compared in posterior lumbar fusion procedures. 56 patients with degenerative disc disease, lumbar instability or spinal stenosis, were included. The volume of cells suspension in pre- and post-enrichment and the number of nucleated cells (NCs) were identified. The number of osteoprogenitor cells was estimated by counting the colony-forming units which express alkaline phosphatase (CFUs/ALP+). Then the efficiency of the enrichment was evaluated. Clinical follow-up with roentgenogram and Oswestry scale scores was performed for outcome evaluation. RESULTS: (249 +/- 31) ml bone marrow per patient from bilateral iliac crests was aspirated peri-operatively. About (43 +/- 11) ml enriched bone marrow was collected. The number of NCs was concentrated from (15.9 +/- 3.3) x 10(6)/ml to (44.1 +/- 10.8) x 10(6)/ml, CFUs/ALP+ was significantly increased from (118 +/- 86)/ml to(486 +/- 305)/ml. The follow-up was about (26.3 +/- 7.5) months. There was no significant differences in age, gender, disease and fusion segments between the two groups. The fusion rate was 93.3% and 96.2% for composite graft group and autograft group, respectively (chi2 = 0.2146, P = 0.6432). There was no difference in operation time between the two group (t = 0.5243, P = 0.6022), but blood loss in composite graft group was more than that in autograft group (t = 6.4664, P < 0.01). Cell salvage for auto-transfusion could transfuse back half of the blood loss during operation. No hematoma or chronic soreness in the bone marrow donor sites of composite graft group occurred, but a little exudation or moderate swelling in the wound happened in 4 cases which disappeared under medical treatment. Meanwhile, 15.4% patients had hematoma in the iliac bone donor site and 26.9% patients had chronic soreness, but no case had wound problem in autograft group. As for Oswestry scale scores, there was no significant difference between the two groups. CONCLUSIONS: The enrichment technique of autologous bone marrow stem cells can greatly increase the concentration of MSCs. It is a rapid and safe method used peri-operatively. The composite material of enriched MSCs and porous beta-TCP is a good bone substitute in posterior spinal fusion.

Proliferation and osteoblastic differentiation of human bone marrow stromal cells on hydroxyapatite/bacterial cellulose nanocomposite scaffolds.

In this study, we prepared hydroxyapatite/bacterial cellulose (HAp/BC) nanocomposite scaffolds utilizing the biomimetic technique, and investigated the proliferation and osteoblastic differentiation of stromal cells derived from human bone marrow (hBMSC) on them. Scanning electron microscopy proved that cells could adhere and spread on scaffolds. The hBMSC seeded on the nanocomposites exhibited better adhesion and activity than those seeded upon the pure BC. After 6 days of culture on scaffolds, the cells proliferated faster on the nanocomposites than on the pure BC, as assessed by Alamar Blue assay. Real-time reverse transcription PCR results showed that the alkaline phosphatase (ALP) activity of hBMSC and the expression of osteopontin, osteocalcin, bone sialoprotein, and ALP mRNA were all higher for up to 7 days for hBMSC cultured on the nanocomposites than for those cultured upon the pure BC with and without the presence of osteogenic supplements (L-ascorbic acid, glycerophosphate, and dexamethasone, p<0.05). These results suggest that the attachment, proliferation, and differentiation in cultured hBMSC can be modulated by the HAp/BC nanocomposite scaffold properties. In summary, we have developed a scaffold that displays in vitro biocompatibility, which may have potential use for bone tissue engineering.

Inhibiting wear particles-induced osteolysis with doxycycline.

AIM: To study the effect of doxycycline (DOX) on osteoclastogenesis, mature osteoclast fate and function, wear particles-induced osteoeolysis, and to provide some foundation for treating aseptic loosening and osteolysis after joint arthroplasty. METHODS: Osteoclasts were generated from mouse bone marrow monocytes with the receptor activator of NF-kappaB ligand and the macrophage colony stimulating factor. DOX at a concentration of 5, 10, 15, and 20 microg/mL was respectively added to the medium. Seven days later, the osteoclasts were determined through tartrate-resistant acid phosphatase (TRAP) staining. Mature osteoclasts were isolated from newborn rabbits and cultured for 3 d in 24-well plates or on bone slices. DOX at a concentration of 5, 10, 15, and 20 microg/mL was respectively added to the medium. After TRAP staining, the osteoclasts were counted, resorption on bone slices was quantified, and the area was calculated after toluidine blue and Mayer-hematoxylin staining. Polymethyl methacrylate (PMMA) or ultra-high molecular weight polyethylene (UHMWPE) particles were implanted on the calvariae of C57BL/J6 mice. DOX, at a dose of 2 and 10 mg x kg(-1) x d(-1), was respectively given intraperitoneally for 7 d. Seven days later, the calvariae were removed and processed for pathological analysis. RESULTS: DOX treatment effectively inhibited in vitro osteoclastogenesis, affected the fate of mature osteoclasts, and inhibited mature osteoclasts, causing bone resorption. In vivo data indicated that DOX strongly inhibited PMMA or UHMWPE-induced osteolysis and osteoclastogenesis. CONCLUSION: DOX can effectively inhibit osteoclastogenesis and affect mature osteoclast fate and suppress wear particles induced by osteolysis and osteoclastogenesis. DOX might be useful in the treatment or prevention of wear particles-induced osteolysis and aseptic loosening for its effect on osteoclast generation and mature osteoclast fate and function.