Genlin Wang

The use of silk fibroin/hydroxyapatite composite co-cultured with rabbit bone-marrow stromal cells in the healing of a segmental bone defect

In a rabbit model we investigated the efficacy of a silk fibroin/hydroxyapatite (SF/HA) composite on the repair of a segmental bone defect. Four types of porous SF/HA composites (SF/HA-1, SF/HA-2, SF/HA-3, SF/HA-4) with different material ratios, pore sizes, porosity and additives were implanted subcutaneously into Sprague-Dawley rats to observe biodegradation. SF/HA-3, which had characteristics more suitable for a bone substitute based on strength and resorption was selected as a scaffold and co-cultured with rabbit bone-marrow stromal cells (BMSCs). A segmental bone defect was created in the rabbit radius. The animals were randomised into group 1 (SF/HA-3 combined with BMSCs implanted into the bone defect), group 2 (SF/HA implanted alone) and group 3 (nothing implanted). They were killed at four, eight and 12 weeks for visual, radiological and histological study. The bone defects had complete union for group 1 and partial union in group 2, 12 weeks after operation. There was no formation of new bone in group 3. We conclude that SF/HA-3 combined with BMSCs supports bone healing and offers potential as a bone-graft substitute.

Osteoporotic vertebral compression fractures with an intravertebral cleft treated by percutaneous balloon kyphoplasty

We investigated the safety and efficacy of treating osteoporotic vertebral compression fractures with an intravertebral cleft by balloon kyphoplasty. Our study included 27 patients who were treated in this way. The mean follow-up was 38.2 months (24 to 54). The anterior and middle heights of the vertebral body and the kyphotic angle were measured on standing lateral radiographs before surgery, one day after surgery, and at final follow-up. Leakage of cement was determined by CT scans. A visual analogue scale and the Oswestry disability index were chosen to evaluate pain and functional activity. Statistically significant improvements were found between the pre- and post-operative assessments (p < 0.05) but not between the post-operative and final follow-up assessments (p > 0.05). Asymptomatic leakage of cement into the paravertebral vein occurred in one patient, as did leakage into the intervertebral disc in another patient. We suggest that balloon kyphoplasty is a safe and effective minimally invasive procedure for the treatment of osteoporotic vertebral compression fractures with an intravertebral cleft.

Is kyphoplasty reliable for osteoporotic vertebral compression fracture with vertebral wall deficiency

BACKGROUND Vertebral compression fractures are a common clinical manifestation of osteoporosis. The introduction of kyphoplasty has allowed minimally invasive treatment of these fractures. However, in patients with loss of vertebral wall integrity, balloon kyphoplasty is contraindicated due to the possibility of extruding wall fragments into the canal and cement extravasation. We evaluated the efficacy and safety of kyphoplasty in the treatment of vertebral compression fractures in patients with compromised vertebral walls using individualised surgical techniques to avoid cement extravasation. METHODS Symptomatic vertebral fractures (59 fractures in 55 patients) were treated by kyphoplasty. In levels with compromised anterior vertebral walls, two distinct sequential applications of cement were performed to avoid anterior leakage. In levels that demonstrated posterior or lateral wall deficiencies, the cement was injected under live fluoroscopy to monitor lateral or posterior extravasation. Radiographic outcomes were evaluated by comparing pre- and postoperative anterior/middle vertebral body height and local kyphotic angle. Clinical outcomes were evaluated by comparing Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) values preoperatively, postoperatively, and at 3-, 6- and 12-month follow-ups. RESULTS Symptomatic cement extravasation and complications after kyphoplasty were not observed. Vertebral height was restored and the mean kyphotic angle was improved. The mean VAS decreased significantly from pre-surgery to post-surgery, as did the ODI (p<0.05). CONCLUSION Kyphoplasty is a safe, clinically effective treatment for osteoporotic vertebral fracture with peripheral wall damage when using individualised surgical techniques to prevent bone cement leakage.

Risk factors for postoperative wound infections of sacral chordoma after surgical excision.

Study Design A retrospective study, analyzing the risk factors for postoperative wound infections of the sacral chordoma after surgical excision. Objective To determine the preoperative, intraoperative, and patient characteristics that contribute to an increased risk of postoperative wound infection in patients undergoing sacral chordoma resection. Summary of Background Data Postoperative wound infection after spinal operations is a dreaded complication. The risk factors have been investigated earlier, but the patients with sacral chordoma may be distinct. Methods Between January 1992 and December 2007, 45 patients with sacral chordomas were treated with surgical resection. Data regarding preoperative and intraoperative risk factors for postoperative wound infection were evaluated using univariate analysis and multivariable conditional logistic regression. Odds ratios with 95% confidence intervals and P values were calculated. Results Of the 45 patients with sacral chordoma, 16 (35.6%) acquired postoperative wound infection. Significant risk factors associated with postoperative wound infection in the univariate analysis included the following: albumin <3.0, previous surgery, operating time, instrumentation, and surgical team. Albumin<3.0, operating time >6 hours, and previous surgery were statistically significant in the multivariable model. Conclusions Patients undergoing sacral tumor surgery may be at greater risk for developing wound complications. In this study, it seems that albumin<3.0, operating time >6 hours, and previous surgery may predict those patients that were more prone to developing postoperative wound infection. Using a single surgical team and no instrumentation seems to provide protection against postoperative wound infection in this patient population.

Balloon kyphoplasty in the treatment of osteoporotic vertebral compression fracture nonunion.

Patients with nonunion of osteoporotic vertebral compression fractures that are refractory to conservative treatments have persistent back pain, progressive vertebral body collapse and kyphosis, and mobility of the fracture. Although many previous reports have reported vertebral compression fractures treated by balloon kyphoplasty, few data is available on using this method to treat nonunion of vertebral compression fractures. This study evaluated the therapeutic potential of balloon kyphoplasty in the treatment of nonunion of osteoporotic vertebral compression fractures. Twenty-one patients with nonunion of osteoporotic vertebral compression fractures were treated with balloon kyphoplasty. The criteria for diagnosis of nonunion osteoporotic vertebral compression fractures included the following: (1) history of pain for at least 6 months at the fracture site; (2) low T1- and high T2-signal on magnetic resonance images; (3) widening of fracture line on routine radiographs; and (4) movement of the endplate and changes of anterior vertebral heights on hyperextension radiographs. All patients were followed for 9 to 33 months postoperatively (mean 25 months). Statistically significant improvements in the mean postoperative anterior and middle vertebral body heights were observed compared with preoperative values. There was also statistically significant improvement in the mean values for Cobbs angle, pain (visual analog scale), and the Oswestry Disability Index at the postoperative assessment compared with the preoperative assessment. No statistically significant differences were noted between the postoperative and final follow-up assessment in any of the evaluated efficacy measures. The study suggests that balloon kyphoplasty is an effective technique to treat nonunion of osteoporotic vertebral compression fractures.

Pre-operative transarterial embolization for treatment of primary sacral tumors.

Pre-operative embolization of hypervascular spinal tumors can be helpful in tumour resection; however, few studies have been reported on its effectiveness in sacral tumors. We aimed to investigate the value of surgical excision with pre-operative transarterial embolization for primary sacral tumors and evaluate the long-term follow-up outcomes. Data were obtained from a consecutive series of 60 patients (33 female, 27 male) who had sacral tumors and who, between 1992 and 2007, underwent surgical excision in conjunction with arterial embolization. The evaluation parameters included intraoperative blood loss, transfusion, treatment, local recurrence and complications associated with surgery. All tumor masses were resected without intraoperative shock or death. The mean intraoperative blood loss was 1168.3mL (range: 200-5700mL) and the mean transfusion amount was 5.2 units (range: 0-35 units). Radical wide excision was performed on eight patients, marginal excision was conducted for 34 patients and intralesional excision was undertaken for the remaining 18 patients. The mean follow-up period was 75.2months (range: 15-180months). Nineteen (31.7%) patients developed local recurrences. Of the patients who had at least the second sacral roots and the unilateral S3 preserved, 33 (84.6%) had normal bladder function and 34 (87.2%) had normal bowel control. Pre-operative arterial embolization may significantly reduce the likelihood of intraoperative hemorrhage, and has the potential to assist surgeons in completing tumor resection and improving the outcomes for these patients.

Surgery for thoracic myelopathy caused by ossification of the ligamentum flavum

Between January 1996 and December 2003, our department treated 16 patients (10 men and 6 women; average age 57.5 years) by performing a laminectomy for thoracic myelopathy caused by ossification of the ligamentum flavum (OLF). We followed up all patients for 36 to 86 months (mean follow-up time, 57.3 months). The mean (+/-standard deviation) Japanese Orthopaedic Association score increased from 5.0+/-1.4 points before the operation to 7.7+/-1.9 points at the last follow-up (p<0.01). The average values for pre-operative and post-operative kyphosis of the involved vertebrae were 5.8 degrees +/-4.1 degrees and 8.8 degrees +/-6.0 degrees , respectively; the mean increase in kyphosis was only 3.0 degrees +/-2.4 degrees . An intraoperative dural tear was the main complication and none of the patients developed severe neurological complications. We conclude that laminectomy was both effective and safe in the treatment of thoracic OLF, but it must be performed with great care because of frequent dural adhesions to the OLF. The increase in kyphosis after the laminectomy was minimal when most of the facet joints were left intact and when the patient followed a back extensor exercise program post-operatively.

Evaluation of calcium phosphate and calcium sulfate as injectable bone cements in sheep vertebrae.

Study Design An animal study. Objective To compare the biomechanical and biometabolic properties between calcium phosphate (CaP), calcium sulfate (CaS), and polymethylmethacrylate (PMMA) as bone void fillers in a sheep model of lumbar vertebral defect. Summary of Background Data PMMA is commonly used as a bone void filler in vertebroplasty and kyphoplasty. However, it has certain intrinsic limitations. CaP and CaS are considered as potential PMMA substitutes, but further in vivo evaluations of their biomechanical and biometabolic properties are needed before they can be recommended for clinical use in routine vertebroplasty and kyphoplasty procedures. Methods Bone voids were experimentally created on lumbar vertebrae L2‐L5 with L6 left intact as a normal control in 24 adult female sheep. The defect vertebrae L2‐L5 in each of the animals were randomized to receive no filler augmentation (controls) or augmentation with CaP, CaS, or PMMA. Animals were killed after 2, 12, and 24 weeks of the bone filler augmentation, respectively. Vertebrae L2‐L6 were collected and their biomechanical strength/stiffness, osseointegration activity, and biodegradability were evaluated. Results At all 3 time points tested, the PMMA‐augmented lumbar vertebra had the highest biomechanical strength and stiffness, followed by the intact vertebra L6. CaP and CaS significantly improved the strength as compared with the sham augmentation, but did not yet restore it to the normal level. Osteogenesis occurred at low levels in the empty vertebrae, in the CaP‐augmented defect vertebrae at 12 and 24 weeks, and in the CaS‐augmented vertebrae at 12 weeks, but at a substantially high level after 24 weeks of CaS augmentation. The filler biodegradation rate was low in the CaP‐augmented vertebrae, but was substantially high in the CaS‐augmented vertebrae. Conclusions CaP and CaS are effective enough to strengthen the fractured lumbar vertebrae in a time‐dependent manner, although not as good as PMMA. CaS has a much higher osseointegration capacity than CaP.

Kyphoplasty for the Treatment of Painful Osteoporotic Thoracolumbar Burst Fractures

This study explored the feasibility and clinical outcome of kyphoplasty for the treatment of painful osteoporotic thoracolumbar burst fractures without neurological deficit. A total of 25 consecutive patients with painful type-A3 amyelic thoracolumbar fractures without neurological deficit were treated by kyphoplasty. Pain was measured using the self-reporting visual analog pain scale (VAS) preoperatively, postoperatively, and at 6-month follow-up. Disability was measured using the Oswestry Disability Index (ODI) preoperatively, postoperatively, and at 6-month follow-up. The height of the fractured vertebral body, kyphotic angle, and spinal canal compromise were measured preoperatively, postoperatively, and at 6-month follow-up. Relief of pain was achieved 24 hours postoperatively. Mean VAS score decreased from 8.2+/-1.3 preoperatively to 2.8+/-0.8 postoperatively (P<.05), and was maintained at 2.9+/-1.1 at 6-month follow-up. The ODI score varied from 68.2%+/-6.6% preoperatively to 35.3%+/-2.8% postoperatively (P<.05). Improvement was maintained at 6-month follow-up. Postoperatively, the height of anterior vertebrae (Ha) was restored from 61.5%+/-13.9% to 85.3%+/-10.6%, the height of midline vertebrae (Hm) restored from 73.0%+/-19.3% to 83.3%+/-7.4%, the kyphotic angle from 21.7 degrees +/-7.8 degrees to 8.6 degrees +/-6.6 degrees, and the spinal canal compromise from 20.1%+/-4.1% to 17.8%+/-1.3%. At 6-month follow-up, maintenance of the height restoration and kyphotic deformity correction was found. No significant difference was noted in pre- and postoperative spinal canal compromise. Kyphoplasty is a relatively safe and effective method for the treatment of painful osteoporotic thoracolumbar burst fractures.

Kyphoplasty for the Treatment of Kümmell's Disease

The peripheral cortex of a vertebral body affected by Kümmells disease is not always intact, resulting in high risk for cement leakage. This study used modified techniques to avoid cement extravasation and dislodgment and investigated the feasibility and efficacy of kyphoplasty for treatment of Kümmells disease. Between May 2006 and May 2008, 21 consecutive patients with Kümmells disease underwent kyphoplasty with modified techniques. Each patient was assessed preoperatively with standard examinations and imaged with dynamic radiographs, 3-dimensional computed tomography scans, and magnetic resonance imaging. A visual analog scale (VAS) and the Oswestry Disability Index were used to measure pain and disability pre- and postoperatively and at 6- and 12-month follow-up. One patient had cement leakage into the disk space but no clinical symptoms. There were no cases of cement dislodgment at follow-up. Comparison of the pre- vs postoperative VAS scores revealed significant differences (P<.05), whereas VAS scores at 6- vs 12-month follow-up were similar. The Oswestry Disability Index scores varied from 62.3%+/-15.1% preoperatively to 35.2%+/-12.1% postoperatively (P<.05). This improvement in scores was still present at 6- and 12-month follow-up. At 6- and 12-month follow-up, maintenance of height restoration and kyphotic deformity correction was found. Kyphoplasty may be a relatively safe and effective method for treatment of Kümmells disease when modified techniques are used to prevent cement leakage and dislodgment.