Li-Jen Yuan

Arthroscopically assisted osteosynthesis for tibial plateau fractures.

BACKGROUND Options for management of tibial plateau fracture are numerous, and the outcome depends on several factors. With the inherent advantages of arthroscopy, the results of tibial plateau fracture have been greatly improved. METHODS Thirty-one patients were treated with arthroscopically assisted reduction for tibial plateau fracture, with an average follow-up period of 3 years. Evaluations were performed with the Hospital for Special Surgery knee score clinically, and with the Ahlbäck scale for osteoarthritis radiographically. RESULTS Eighty percent of cases were Schatzker type II, III, or IV, and over half (52%) of the patients had concomitant intra-articular lesions. Twenty-nine patients (93.5%) had satisfactory results according to the Hospital for Special Surgery knee score, and only one patient developed degenerative arthritis during the period of follow-up. CONCLUSION The arthroscopically assisted reduction of tibial plateau fracture is a safe and promising procedure. The results are comparable to traditional methods of open reduction.

Arthroscopically assisted osteosynthesis of complex intra-articular fractures of the distal radius

BACKGROUND Complex intra-articular fractures of the distal radius pose a great challenge in orthopedic surgery. Conventional open reduction and internal fixation generally yields poor functional outcome. The technique of arthroscope-assisted surgery allows more accurate reduction of the articular surface and treatment of soft tissue lesions, both of which are necessary for regaining anatomic structure and satisfactory function. METHODS Twenty wrists in 18 patients with intra-articular fracture of the distal radius received arthroscopic surgery and percutaneous pinning with or without external skeletal fixation and bone grafting. A new traction method was designed that allows arthroscopic surgery and fluoroscopic monitoring to be performed simultaneously. Postoperative follow-up averaged 24.7 months. RESULTS All except one of these patients returned to work within 3 to 6 months after surgery. Later collapse with minimal articular step-off was noted on radiographs before osseous union in two patients who did not undergo bone grafting. Decreased radial height because of subsequent displacement at the metaphyseal fracture was noted in one patient who did not receive external skeletal fixation initially. CONCLUSION The technique of arthroscope-assisted surgery, despite a steep learning curve, is an invaluable method. Results using this technique are promising and few complications are encountered in the treatment of complex radius platform fractures. The bone grafting procedure augments osseous union, shortens the duration of external skeletal fixation, and thus lessens joint stiffness.

Use of fluorescence labeled mesenchymal stem cells in pluronic F127 and porous hydroxyapatite as a bone substitute for posterolateral spinal fusion

Posterolateral spinal fusion is used to treat patients with degenerative spinal disorders. We investigated the effectiveness of a mesenchymal stem cell (MSC)/Pluronic F127/Interpore hybrid graft for spinal fusion in rabbits. Spinal fusion was examined using radiography, manual palpation, computed tomography (CT), torsional loading tests, and histological analysis. Using a PKH fluorescence labeling system, we also examined whether the newly formed bone was derived from the transplanted MSCs. We found that the MSCs adhered to the Interpore surface and within its pores, and differentiated into osteoblasts. Radiographs and CT images showed a continuous bone bridge and a satisfactory fusion mass incorporated into the transverse processes. The results of manual palpation and biomechanical data did not differ significantly from an autograft group. Histology from both groups revealed the presence of fibrous tissue, cartilage, and endochondral ossification in the gaps between the grafted fragments. In both groups, the degree of mature bone formation was greater at 12 weeks than at 6 weeks after grafting. Quantitative histomorphometry revealed no significant differences between the two groups at either time point. In situ tracing of the PKH 67‐labeled MSCs indicated that the transplanted MSCs were partly responsible for the new bone formation in both the repaired transverse processes and the grafted fragments. Thus, the MSC/Pluronic F127/Interpore hybrid graft could be used effectively to achieve posterolateral spinal fusion.

In vivo study of hot compressing molded 50:50 poly (DL-lactide-co-glycolide) antibiotic beads in rabbits

The authors investigated poly (DL‐lactide‐co‐glycolide) beads as an antibiotic delivery system in vivo for the treatment of various surgical infections. In this study, the copolymer 50:50 poly (DL‐lactide):co‐glycolide was mixed with vancomycin powder and hot compressing molded at 55°C to form 8 mm in diameter biodegradable antibiotic beads. The antibiotic beads were implanted in the distal femoral cavities of rabbits for in vivo investigation. The local concentration of vancomycin was well above the breakpoint sensitivity concentration (the antibiotic concentration at the transition point between bacterial killing and resistance to the antibiotic) for 56 days. The release was most marked during the first day. The diameters of the sample inhibition zone ranged from 8 to 18 mm, and the relative activity of vancomycin ranged from 9.1% to 100%. Only low systemic blood levels of vancomycin were measured after beads implantation. There was no increase in the concentration of blood urea nitrogen and serum creatinine after the implantation. Histological observations showed that the bead materials were biodegradable, resorbed slowly, and did not cause a significant host reaction. This study offers a biodegradable delivery system of antibiotics to treat various surgical infections.

Beneficial effects of hyperbaric oxygen on human degenerated intervertebral disk cells via suppression of IL-1β and p38 MAPK signal.

Nucleus pulposus cells (NPCs) from degenerating disks produce catabolic and inflammatory factors, including interleukin (IL)‐1, nitric oxide (NO), prostaglandin E2 (PGE‐2), and matrix metalloproteinaes (MMPs). An imbalance between MMPs and tissue inhibitors of matrix metalloproteinases (TIMPs) has been proposed to exist in the degenerating disk. This study evaluates the effects of hyperbaric oxygen (HBO) on the human degenerated NPCs. NPCs were maintained in alginate bead culture. All hyperoxic cells were exposed to 100% O2 at 2.5 atmospheres absolute (ATA) in a hyperbaric chamber. p38 MAPK phosphorylation of the NPCs was detected using the phosphor‐kinase array kit. RNA was isolated for real‐time quantitative polymerase chain reaction (Q‐PCR) analysis of aggrecan and type II collagen gene expression. The amounts of IL‐1β, NO, PGE‐2, MMP‐3, and TIMP‐1 in the conditioned media were quantified by enzyme‐linked immunosorbent assay (ELISA). Our data showed that HBO treatment decreased expression of IL‐1β, increased the gene expression of aggrecan and type II collagen, suppressed the phosphorylation of p38 MAPK, decreased NO, PGE‐2, and MMP‐3, and increased TIMP‐1 expression in NPCs as compared with the atmospheric treatment. These results support the hypothesis that IL‐1β and the p38 MAPK signal may be responsible for many of the inflammatory and catabolic changes seen in the human disk degeneration, and support our proposal that HBO treatment‐induced increase of the anabolic factor (TIMP‐1)/catabolic factor (MMP‐3) ratio may provide a therapeutic approach to slow the course of intervertebral disk degeneration.

The use of fluorescence-labeled mesenchymal stem cells in poly(lactide-co-glycolide)/hydroxyapatite/collagen hybrid graft as a bone substitute for posterolateral spinal fusion.

BACKGROUND Posterolateral spinal fusion is used to treat patients with degenerative spinal disorders. In this study, we investigated the effectiveness of a mesenchymal stem cell (MSC)/hydroxyapatite/type I collagen hybrid graft for posterolateral spinal fusion in a rabbit model. METHODS In vitro study, the hybrid graft was cultured in complete or osteogenic medium for 7 days and 14 days and examined by scanning electron microscopy. The alkaline phosphatase activity of the MSCs was assessed and the expression of osteogenic gene was determined by reverse transcription polymerase chain reaction. In vivo investigation, spinal fusion was examined using radiography, manual palpation, computed tomography, torsional loading tests, and histologic analysis. Furthermore, using a PKH fluorescence labeling system, we examined whether the newly formed bone was derived from the transplanted MSCs. RESULTS Our data suggested that the MSCs differentiated into osteoblasts and produced extracellular matrix in the hybrid graft. Increased alkaline phosphatase activity was noted and mRNA of Cbfa-1 and osteopontin were detected. Radiographs and computed tomography images showed a continuous bone bridge and a satisfactory fusion mass incorporated into the transverse processes. The results of manual palpation and biomechanical data did not significantly differ between the two groups. Histologic examination of both groups revealed the presence of cartilage and endochondral ossification in the gaps between the grafted fragments. In situ tracing of the PKH 67-labeled MSCs indicated that the transplanted MSCs were partly responsible for the new bone formation. CONCLUSION The hybrid graft could be effectively used to achieve posterolateral spinal fusion.

Early Administration of Hyperbaric Oxygen Therapy in Distraction Osteogenesis: A Quantitative Study in New Zealand Rabbits

BACKGROUND We investigated the effect of hyperbaric oxygen (HBO) therapy on the early phase of tibial lengthening in our established rabbit model. METHODS Twenty-four male rabbits (six per group) underwent right tibial lengthening by 5 mm. Group 1 then underwent 2.5 atmospheres of absolute hyperbaric oxygenation for 2 hours daily for 6 weeks postoperatively; group 2, for early 5 weeks (weeks 1-5), group 3, for late 5 weeks (weeks 2-6), and group 4 had no HBO therapy. Bone mineral density (BMD) was measured before surgery and weekly thereafter from weeks 2 through 6. The mechanical strengths of the lengthened tibias were measured. RESULTS Significantly higher mean %BMDs were obtained for groups 1 and 2 compared with groups 3 and 4. There was no difference in the mean %BMD between groups 1 and 2 (p > 0.05). The results were similar for mean percentage maximal torque; group 1 had the maximum torque, followed sequentially by groups 2 though 4. CONCLUSION The study results suggest that early and full-term administration of HBO therapy on tibial lengthening may achieve better benefits.

Hyperbaric oxygen treatment prevents nitric oxide‐induced apoptosis in articular cartilage injury via enhancement of the expression of heat shock protein 70

Heat shock proteins (HSPs), inflammatory cytokines, nitric oxide (NO), and localized hypoxia‐induced apoptosis are thought to be correlated to the degree of cartilage injury. We investigated the effect of hyperbaric oxygen (HBO) on (1) interleukin‐1β (IL‐1β)‐induced NO production and apoptosis of rabbit chondrocytes and (2) healing of articular cartilage defects. For the in vitro study, RT‐PCR and Western blotting were performed to detect mRNA and protein expressions of HSP70, inducible NO synthase (iNOS), and caspase 3 in IL‐1β‐treated chondrocytes. To clarify that the HSP70 was necessary for anti‐iNOS and anti‐apoptotic activity by HBO, we treated the cells with an HSP70 inhibitor, KNK437. For the in vivo study, cartilage defects were created in rabbits. The HBO group was exposed to 100% oxygen at 2.5 ATA for 1.5 h a day for 10 weeks. The control group was exposed to normal air. After sacrifice, specimen sections were sent for examination using a scoring system. Immunohistochemical analyses were performed to detect the expressions of iNOS, HSP70, and caspase 3. Our results suggested that HBO upregulated the mRNA and protein expressions of HSP70 and suppressed those of iNOS and caspase 3 in chondrocytes. KNK437 inhibited the HBO‐induced downregulation of iNOS and casapase 3 activities. The histological scores showed that HBO markedly enhanced cartilage repair. Immunohistostaining showed that HBO enhanced HSP70 expression and suppressed iNOS and caspase 3 expressions in chondrocytes. Accordingly, HBO treatment prevents NO‐induced apoptosis in articular cartilage injury via enhancement of the expression of heat shock protein 70.

Hyperbaric oxygen treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells

Nucleus pulposus cells (NPCs) from degenerating discs produce catabolic and inflammatory factors, including interleukin (IL)‐1 and nitric oxide (NO). Enhanced production of NO has been implicated in the apoptosis of degenerating disc cells. This study evaluates the effects of hyperbaric oxygen (HBO) on degenerated human NPCs. All hyperoxic cells were exposed to 100% O2 at 2.5 atmospheres absolute (ATA). Phosphorylation of extracellular signal‐regulated kinase 1/2 (ERK1/2), c‐Jun N‐terminal kinase (JNK), and p38 mitogen‐activated protein kinase (MAPK) in NPCs was detected using the phosphor‐kinase array kit. RNA was isolated for real‐time polymerase chain reaction (PCR) analysis of aggrecan and type II collagen gene expression. The levels of IL‐1β and NO were quantified by enzyme‐linked immunosorbent assay (ELISA). To identify the HBO‐induced anti‐apoptotic pathways, expression of Bcl‐2 and Bax proteins as well as activation of cysteine‐containing aspartate‐specific proteases (caspases) 3, 8, and 9 was evaluated using Western blotting after HBO treatment. Our data showed that HBO treatment decreased the expression of IL‐1β, suppressed phosphorylation of ERK1/2, JNK, and p38 MAPK, decreased synthesis of NO, and increased the gene expression of aggrecan and type II collagen in NPCs as compared with the atmospheric treatment. HBO up‐regulated the ratio of Bcl‐2 to Bax expression and reduced the activity of caspases 9 and 3 but not of caspase 8, indicating a selective effect over the mitochondrial apoptosis pathway in degenerated NPCs. These results support our hypothesis that HBO treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells.

Benefits of biphasic calcium phosphate hybrid scaffold-driven osteogenic differentiation of mesenchymal stem cells through upregulated leptin receptor expression

BackgroundThe use of mesenchymal stem cells (MSCs) and coralline hydroxyapatite (HA) or biphasic calcium phosphate (BCP) as a bone substitute for posterolateral spinal fusion has been reported. However, the genes and molecular signals by which MSCs interact with their surrounding environment require further elucidation.MethodsMSCs were harvested from bone grafting patients and identified by flow cytometry. A composite scaffold was developed using poly(lactide-co-glycolide) (PLGA) copolymer, coralline HA, BCP, and collagen as a carrier matrix for MSCs. The gene expression profiles of MSCs cultured in the scaffolds were measured by microarrays. The alkaline phosphatase (ALP) activity of the MSCs was assessed, and the expression of osteogenic genes and proteins was determined by quantitative polymerase chain reaction (Q-PCR) and Western blotting. Furthermore, we cultured rabbit MSCs in BCP or coralline HA hybrid scaffolds and transplanted these mixtures into rabbits for spinal fusion. We investigated the differences between BCP and coralline HA hybrid scaffolds by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT).ResultsTested in vitro, the cells were negative for hematopoietic cell markers and positive for MSC markers. There was higher expression of 80 genes and lower of 101 genes of MSCs cultured in BCP hybrid scaffolds. Some of these genes have been shown to play a role in osteogenesis of MSCs. In addition, MSCs cultured in BCP hybrid scaffolds produced more messenger RNA (mRNA) for osteopontin, osteocalcin, Runx2, and leptin receptor (leptin-R) than those cultured in coralline HA hybrid scaffolds. Western blotting showed more Runx2 and leptin-R protein expression in BCP hybrid scaffolds. For in vivo results, 3D reconstructed CT images showed continuous bone bridges and fusion mass incorporated with the transverse processes. Bone mineral content (BMC) values were higher in the BCP hybrid scaffold group than in the coralline HA hybrid scaffold group.ConclusionsThe BCP hybrid scaffold for osteogenesis of MSCs is better than the coralline HA hybrid scaffold by upregulating expression of leptin-R. This was consistent with in vivo data, which indicated that BCP hybrid scaffolds induced more bone formation in a spinal fusion model.