Ming-Chau Chang

Is fusion necessary for surgically treated burst fractures of the thoracolumbar and lumbar spine? : A prospective, randomized study

Study Design. A prospective clinical trial was conducted. Objectives. To compare the results of fusion versus nonfusion for surgically treated burst fractures of the thoracolumbar and lumbar spine. Summary of Background Data. The operative results of surgically treated burst fractures with short segmental fixation have been well documented. There is no report comparing the results of fusion and nonfusion. Methods. Fifty-eight patients were included in this study, with the inclusion criteria as follows: neurologically intact spine with a kyphotic angle ≥20°, decreased vertebral body height ≥50% or a canal compromise ≥50%, incomplete neurologic deficit with a canal compromise <50%, complete neurologic deficit, and multilevel spinal injury or multiple traumas. All patients were randomly assigned to fusion or nonfusion groups, and operative treatment with posterior reduction and instrumentation was carried out. Posterior fusion with autogenous bone graft was performed for the fusion group (n = 30), and no fusion procedure was done for the nonfusion group (n = 28). The average follow-up period was 41 months (range, 24–71 months). Results. The average loss of kyphotic angle was not statistically significant between these 2 groups. The radiographic parameters were statistically significantly better in the nonfusion group, including angular change in the flexion-extension lateral view (4.8° vs. 1.0°), lost correction of decreased vertebral body height (3.6% vs. 8.3%), intraoperative estimated blood loss (303 mL vs. 572 mL), and operative time (162 minutes vs. 224 minutes). The scores on the low back outcome scale were not statistically significant for these 2 groups. Conclusions. The short-term results of short segmental fixation without fusion for surgically treated burst fractures of the thoracolumbar spine were satisfactory. The advantages of instrumentation without fusion are the elimination of donor site complications, saving more motion segments, and reducing blood loss and operative time.

Efficacy of dilute betadine solution irrigation in the prevention of postoperative infection of spinal surgery.

Study Design. Prospective, single-blinded, randomized study. Objectives. To evaluate the efficacy of dilute betadine irrigation of spinal surgical wounds in prevention of postoperative wound infection. Summary and background. Deep wound infection is a serious complication of spinal surgery that can jeopardize patient outcomes and increase costs. Povidoneiodine is a widely used antiseptic with bactericidal activity against a wide spectrum of pathogens, including methicillin-resistant Staphylococcus aureus. The aim of this study was to evaluate the efficacy of dilute betadine solution in the prevention of wound infection after spinal surgery. Methods. Four hundred and fourteen patients undergoing spinal surgery were randomly assigned to two groups. In group 1 (208 patients), surgical wounds were irrigated with dilute betadine solution (3.5% betadine) before wound closure. Betadine irrigation was not used in group 2 (206 patients). Otherwise, perioperative management was the same for both groups. Results. Mean length of follow-up was 15.5 months in both groups (range, 6–24 months). No wound infection occurred in group 1. One superficial infection (0.5%) and six deep infections (2.9%) occurred in group 2. The differences between the deep infection rate (P = 0.0146) and total infection rate (P = 0.0072) were significant between the two groups. Conclusions. Our report is the first prospective, single-blinded, randomized study to evaluate the clinical effectiveness of dilute betadine solution irrigation for prevention of wound infection following spinal surgery. We recommended this simple and inexpensive measure following spinal surgery, particularly in patients with accidental wound contamination, risk factors for wound infection, or undergoing surgery in the absence of routine ultraviolet light, laminar flow, and isolation suits.

Polymethylmethacrylate augmentation of pedicle screw for osteoporotic spinal surgery: a novel technique.

Study Design. A retrospective study to evaluate the clinical results of patients with osteoporosis and various spinal diseases treated surgically with polymethylmethacrylate (PMMA) augmented pedicle screw. Objective. To report a novel technique using PMMA for pedicle screw augmentation in osteoporotic spinal surgery. Summary of Background Data. Many studies have proved that the stiffness and strength of pedicle screw fixation can be significantly increased when the pedicle screw is augmented with various cements. However, most of those studies were experimental. Clinical reports using those materials for pedicle screw augmentation are rare and a practical and reliable technique for primary pedicle screw augmentation with cement has not yet been established. Methods. Forty-one patients [23 female, 18 male, mean age 75.1 (50–90) years] with osteoporosis and various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of pedicle screw. Pre-and postoperative scores for visual analogue scale for pain and Oswestry disability index questionnaire were analyzed. The screw migration, which is the distance from the screw tip to the anterior cortex and upper endplate of vertebra, was also evaluated immediately after the operation and at the mean 22.3 months final follow-up. Results. Totally 291 of 300 screws were augmented with PMMA. There was neither neurologic deterioration nor symptomatic cement leakage after surgery. The mean visual analogue scale pain score of these patients improved from 9.2 to 1.5 (P < 0.01) and the functional Oswestry disability index score improved from 77.5% to 44.2% (P < 0.01). Kyphotic deformity was improved from average 23.2° to 11.9° after surgery, and to 14.9° at final follow-up (P < 0.01). The average loss of kyphosis correction was 3°. There was no significant screw migration when the screws distances just after operation and at the final follow-up were compared (P > 0.01). Conclusion. The presented technique of PMMA for augmentation of pedicle screw is a safe, reliable, and practical technique for osteoporotic patients who also had various spinal diseases and need spinal instrumentation.

Mesenchymal stem cells promote growth and angiogenesis of tumors in mice

Though the early integration of mesenchymal stem cells (MSCs) into tumor-associated stroma of cancer has been demonstrated, the functional contributions and underlying mechanisms of these cells to tumor growth and angiogenesis remain to be clarified. Using a xenograft model, human colorectal cancer cells, MSCs, and their cell mixture were introduced to a subcutaneous site of immunodeficient mice. The tumor growth rate and angiogenesis of each transplantation was then compared. We demonstrate that a variety of colorectal cancer cells, when mixed with otherwise non-tumorigenic MSCs, increase the tumor growth rate and angiogenesis more than that when mixed with carcinoma-associated fibroblasts or normal colonic fibroblasts. The secretion of interleukin-6 (IL-6) from MSCs increases the secretion of endothelin-1 (ET-1) in cancer cells, which induces the activation of Akt and ERK in endothelial cells, thereby enhancing their capacities for recruitment and angiogenesis to tumor. The IL-6/ET-1/Akt or ERK pathway of tumor-stroma interaction can be targeted by an antibody against IL-6 or Lentiviral-mediated RNAi against IL-6 in MSCs, by inhibition or knockdown of ET-1 in cancer cells, or by inhibition of ERK and Akt in host endothelial cells. These demonstrate that attempts to interrupt the interaction of MSCs and cancer cells help to abrogate angiogenesis and inhibit tumor growth in tumors formed by cancer cells admixed with MSCs. These data demonstrate that the tumor microenvironment, namely, MSCs-secreted IL-6, may enrich the proangiognic factors secreted by cancer cells to increase angiogenesis and tumor growth and that targeting this interaction may lead to novel therapeutic and preventive strategies.

Tuberculous Spondylitis and Pyogenic Spondylitis : Comparative Magnetic Resonance Imaging Features

Study Design. We retrospectively compared magnetic resonance images (MRIs) of tuberculous (TB) spondylitis and pyogenic spondylitis. Objective. To identify differences between the diseases. Summary of Background Data. Clinical and imaging findings of the 2 diseases are hard to distinguish. MRI may show important differences and aid in early diagnosis and treatment. Methods. We compared 22 MRI parameters in 33 patients with TB spondylitis (average age, 66 years) and in 33 patients with pyogenic spondylitis (average age, 65 years). Results. Seventeen parameters significantly differed between the groups. The most important were local and heterogeneous enhancement of the vertebral body in all patients with TB spondylitis, diffuse and homogeneous enhancement of the vertebral body in 94% of patients with pyogenic spondylitis, vertebral intraosseous abscess with rim enhancement (TB vs. pyogenic, 79% vs. 0%), disc abscess with rim enhancement (9% vs. 64%), and well-defined paraspinal abnormal signal intensity (82% vs. 18%). Conclusions. Most parameters occurred in both diseases. Distinctive findings were a pattern of bone destruction with relative disc preservation and heterogeneous enhancement for TB spondylitis and a diskitis pattern (disc destruction) with peridiscal bone destruction and homogeneous enhancement for pyogenic spondylitis. These MRI parameters may facilitate the differential diagnosis of these diseases.

Knockdown of p21Cip1/Waf1 enhances proliferation, the expression of stemness markers, and osteogenic potential in human mesenchymal stem cells

Mammalian aging of many tissues is associated with a decline in the replicative and functional capacity of somatic stem cells. Understanding the basis of this decline is a major goal of aging research. Human bone marrow‐derived multipotent stromal cells (MSCs) have been applied in the treatment of fracture nonunion. Clinical application of MSCs requires abundant cells that can be overcome by ex vivo expansion of cells, but often at the expense of stemness and differentiation potentiality. We first demonstrated that late‐passage MSCs exhibited decreased proliferation capacity, reduced expression of stemness markers such as Oct‐4 and Nanog, and deterioration of osteogenic potential. Further, late‐passage MSCs showed increased expression of p21Cip1/Waf1 (p21), an inhibitor of the cyclin‐dependent kinase. Knockdown of p21 by lentivirus‐mediated shRNAs against p21 in late‐passage MSCs increased the proliferation capacity, the expression of Oct‐4 and Nanog, and osteogenic potential compared with cells transduced with control shRNA. More importantly, reduction in p21 expression in MSCs enhanced the bone repair capacity of MSCs in a rodent calvarial defect model. Knockdown of p21 in MSCs also increased the telomerase activity and telomere length, and did not show chromosomal abnormalities or acquire transformation ability. Therefore, these data successfully demonstrate the involvement of senescence gene in the expression of stemness markers and osteogenic potential of MSCs.

Can povidone-iodine solution be used safely in a spinal surgery?

Intra-operative incidental contamination of surgical wounds is not rare. Povidone-iodine solution can be used to disinfect surgical wounds. Although povidone-iodine is a good broad-spectrum disinfecting agent, it has occasionally been reported to have a negative effect on wound healing and bone union. Therefore, its safety in a spinal surgery is unclear. A prospective, single-blinded, randomized study was accordingly conducted to evaluate the safety of povidone-iodine solution in spinal surgeries. Ascertained herein was the effect of wound irrigation with diluted povidone-iodine solution on wound healing, infection rate, fusion status and clinical outcome of spinal surgeries. Materials and methods: From January 2002 to August 2003, 244 consecutive cases undergoing primary instrumented lumbosacral posterolateral fusion due to degenerative spinal disorder with segmental instability had been collected and randomly divided into two groups: the study group (120 cases, 212 fusion levels) and the control group (124 cases, 223 fusion levels). Excluded were those patients with a prior spinal surgery, spinal trauma, malignant tumor, infectious spondylitis, rheumatoid arthritis, ankylosing spondylitis, metabolic bone disease, skeletal immaturity or with an immunosuppressive treatment. In the former group, wounds were irrigated with 0.35% povidone-iodine solution followed by normal saline solution just before the bone-grafting and instrumentation procedure. However, only with normal saline solution in the latter. All the operations were done by the same surgeon with a standard technique. All the patients were treated in the same postoperative fashion as well. Later on, wound healing, infection rate, spinal bone fusion and clinical outcome were evaluated in both groups. Results: A significant improvement of back and leg pain scores, modified Japanese Orthopedic Association function scores (JOA) and ambulatory capacity have been observed in both groups. One hundred and seven patients in the study group and one hundred and nine in the control group achieved solid union. There was no infection in the study group but six deep infections in the control group. Wound dehiscence was noted in one group 1 and two group 2 patients. A subsequent statistical analysis revealed higher infection rate in the control group (P<0.05), but no significant difference in fusion rate, wound healing, improvement of pain score, function score and ambulatory capacity between the two groups. Conclusion: Diluted povidone-iodine solution can be used safely in spinal surgeries, and it will not influence wound healing, bone union and clinical outcome.

Subsequent vertebral fracture after vertebroplasty: incidence and analysis of risk factors.

Study Design. A retrospective review and analysis of consecutive patients who underwent single-level vertebroplasty at our institute between March 2002 and March 2006. Objective. To analyze the risk factors for subsequent fractures after vertebroplasty and to predict the postoperative fracture-free time and rate. The effect of bone cement volume injected was also evaluated. Summary of Background Data. Previous studies of subsequent fractures after vertebroplasty showed conflicting conclusions about risk factors. The frequency of refracture also varied, ranging from 12% to 52%. Most new fractures occurred at adjacent levels, with different risk factors identified. No data were available on the effect of injected bone cement volume, and no consensus had been reached as to the optimal cement volume. Methods. All enrolled patients were treated with single-level vertebroplasty and followed a standardized postoperative care protocol. Data from medical records and radiographs were collected and analyzed. Variables included patient constitutional factors, radiographic parameters, and volume of injected bone cement. Results. A total of 166 patients (76 men, 90 women) with a mean age of 73.4 years were enrolled in this study. The mean follow-up time was 15.3 months. The overall refracture rate was 38%, with a mean fracture-free interval of 32 months. Both a greater volume of bone cement injected and a greater degree of vertebral height restored contributed significantly to the risk of subsequent adjacent fracture. No risk factor for subsequent remote fracture was identified. A greater volume of bone cement injected was positively correlated with deformity correction after vertebroplasty. Conclusion. Most subsequent fractures occurred at the adjacent level within the first 3 months. Patient preoperative condition did not help predict refracture. Although a greater volume of bone cement injected when performing vertebroplasty contributed to the risk of subsequent adjacent fracture, it resulted in a greater improvement of kyphosis.

Polymethylmethacrylate augmentation of cannulated pedicle screws for fixation in osteoporotic spines and comparison of its clinical results and biomechanical characteristics with the needle injection method.

Study Design: This is a retrospective study carried out to evaluate the clinical results of patients with osteoporosis and various spinal diseases treated surgically with polymethylmethacrylate (PMMA)-augmented cannulated pedicle screws, and to compare this method with the needle injection technique in terms of the clinical results and fixation strength. Objectives: To report a technique using PMMA-augmented cannulated pedicle screws for fixation in osteoporotic spines and to compare its clinical results and biomechanical characteristics with the needle injection technique. Summary of Background Data: Many studies have shown that PMMA-augmented pedicle screws can significantly increase the stiffness and strength of the screw. Various designs of cannulated screws have been used for cement augmentation in experimental studies; however, clinical reports using these screws in osteoporotic patients are rare. A practical and reliable technique and optimal screw design have not yet been established. Methods: Forty-five patients (23 women, 22 men), mean age of 71.37 years (range, 53–94 y), with osteoporosis and various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of cannulated pedicle screws. Preoperative and postoperative visual analog scale scores for pain and the Oswestry disability index questionnaire data were analyzed. Screw migration, which is the distance from the screw tip to the anterior cortex and the upper endplate of the vertebra, was also evaluated immediately after surgery and at the mean follow-up of 15.9 months. These clinical results were then compared with those reported for the needle injection technique. The pullout strength, insertional, and backout torque of these 2 techniques were compared using osteoporotic synthetic bone (0.12 g/cm3). Results: A total of 255 out of 283 cannulated screws were augmented with PMMA. The mean visual analog scale pain score of these patients improved from 9.5 to 3.1 (P<0.01) and the functional Oswestry disability index score improved from 71% to 28.9% (P<0.01). Kyphotic deformity of the compression fracture group (19 patients) was improved from an average of 9.38 to 3.27 degrees after surgery, and to 5.45 degrees at the final follow-up (P<0.01). There was no significant vertical screw migration when the screws’ distances were compared just after the operation and at the final follow-up (P>0.01). However, significant horizontal screw migration was found in lesions below the L2 level (P<0.01). There was no major neurovascular injury, except in 1 patient, who had persistent left thigh pain due to cement leakage at the L1 level, and the symptom was controlled with analgesics. The clinical results of both techniques were satisfactory and there were no significant differences. Although the pullout strength and screw backout torque was significantly higher in the needle injection group (234.1 vs. 187.8 N, 1119.6 vs. 836.7 N mm, respectively), the operation time was shorter and the cement leakage rate was less in the cannulated pedicle screw group than that of the needle injection group (211.4 vs. 296.3 min, 14.05% vs. 26.2%, respectively). Conclusions: The technique of cannulated pedicle screws with PMMA augmentation used in this study can be an option for osteoporotic patients with various spinal diseases who require spinal instrumentation.

Fusidic acid for the treatment of bone and joint infections caused by meticillin-resistant Staphylococcus aureus

There is a lack of surveillance data on resistance to fusidic acid (FA) in Asia, and no reviews of FA usage for the treatment of orthopaedic infections have been conducted since the year 2000. In this study, we present a systemic literature review of FA resistance in Asia and the clinical use of FA for the treatment of bone and joint infections (BJIs). The in vitro activity of FA against meticillin-resistant Staphylococcus aureus (MRSA) isolates remains good, with low (<10%) resistance rates in most Asian countries. FA in Asia appears to be a better oral anti-MRSA agent than trimethoprim/sulfamethoxazole and clindamycin. More than 80 cases of FA use for BJI have been reported since 2000 and the recurrence or failure rate is <10%. There is much evidence supporting the use of FA in combination with other antibiotics (e.g. rifampicin) as an oral treatment following intravenous glycopeptide treatment for BJIs.