THE STUDY ON THE EFFECT OF ARTIFICIAL OSTEOPOROSIS CREATED BY COMBINED OVARIECTOMY AND CALCIUM-RESTRICTED DIETS IN A PORCINE MODEL

This study design is to evaluate the mid-term changes in bone mineral density (BMD) with combined calcium-restricted and ovariectomized miniature porcine models as a large animal model in osteoporosis. The combined old practice hangs on for almost 30 years. Four 6-month-old (T0) female miniature pigs were enrolled in this study. The pigs were fed a normal diet prior to the ovariectomy at the age of 1 year and 3 months (T1) but switched to a diet with restricted calcium content afterwards. Each of the pigs received dual-energy X-ray absorptiometry (DXA) once before ovariectomy, and once every three months (T2, T3, T4) after the ovariectomy to evaluate the changes in BMD. The body weight of all four subject pigs increased significantly during this study ([Formula: see text]). The initial changes in both the BMD levels (T1/T2) were found to be statistically insignificant ([Formula: see text] and [Formula: see text], respectively). However, upon comparison of later BMD changes (T3/T4, T1/T3 and T1/T4), statistically significant elevations were found ([Formula: see text] for all three comparisons). Ovariectomy and calcium-restricted diets are ineffective in achieving an osteoporotic porcine model based on BMD assessments. BMD levels of the subject pigs continued to rise until the point at which body growth had stopped because the ideal pigs for surgical experiments were far from maturity. This finding is not unexpected; after all, the subject pigs are not senile. Without violations of the physiology and Institutional Animal Care and Use Committee (IACUC) regulations, moreover, pigs could be fed by strictly calcium-restricted diets or deprived of soybean component feed. Furthermore, the alternative protocols in osteoporotic porcine model shall perform experiments as soon as possible after ovariectomy. We should take other studies about artificial osteoporotic pigs more into consideration whether it is based on a rational method.

Finite element analysis after rod fracture of the spinal hybrid elastic rod system

Background

The spinal hybrid elastic (SHE) rod dynamic stabilization system can provide sufficient spine support and less adjacent segment stress. This study aimed to investigate the biomechanical effects after the internal fracture of SHE rods using finite element analysis.

Methods

A three-dimensional nonlinear finite element model was developed. The SHE rod comprises an inner nitinol stick (NS) and an outer polycarbonate urethane (PCU) shell (PS). The fracture was set at the caudal third portion of the NS, where the maximum stress occurred. The resultant intervertebral range of motion (ROM), intervertebral disc stress, facet joint contact force, screw stress, NS stress, and PCU stress were analyzed.

Results

When compared with the intact spine model, the overall trend was that the ROM, intervertebral disc stress, and facet joint force decreased in the implanted level and increased in the adjacent level. When compared with the Ns-I, the trend in the Ns-F decreased and remained nearly half effect. Except for torsion, the PS stress of the Ns-F increased because of the sharing of NS stress after the NS fracture.

Conclusions

The study concluded the biomechanical effects still afford nearly sufficient spine support and gentle adjacent segment stress after rod fracture in a worst-case scenario of the thinnest PS of the SHE rod system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05768-x.

Delayed-onset radiculopathy caused by a retropulsed bone fragment after percutaneous kyphoplasty: report of four cases and literature review

Background

Vertebral compression fractures caused by osteoporosis are common in elderly patients and are often encountered by clinical physicians. Percutaneous balloon kyphoplasty (PKP) is widely accepted as a minimally invasive procedure for effectively relieving pain and correcting deformities, but complications may occur. Radiculopathy with a delayed onset caused by a retropulsed bone fragment has not been adequately described in the literature. Thus, this article presents a case report of four cases of retropulsed bone fragment-related radiculopathy after PKP.

Case presentation

In this article, we reported that four out of 251 patients developed radiculopathy after PKP between January 2012 and January 2019 despite experiencing substantial improvements in back pain. All patients with radiculopathy were female and diagnosed with osteoporosis, and their ages ranged from 68 to 89 years. Radiculopathy occurred from 2 to 16 weeks after PKP. All four patients underwent another operation (posterior decompression and instrumentation). Three patients recovered completely, and one died of postoperative intracranial haemorrhage. A detailed imaging study with pre- and postoperative magnetic resonance imaging (MRI) revealed that retropulsed bone fragments that impinged on the corresponding root after PKP were responsible for this complication, and all four patients developed a disrupted posterior vertebral rim preoperatively. No leakage of cement or pedicle track violations were observed.

Conclusion

Although PKP is a safe and effective treatment for painful osteoporotic vertebral compression fractures, a risk of catastrophic neurological injury remains. Radiculopathy with delayed onset caused by a retropulsed bone fragment after kyphoplasty is rare and challenging to treat, and the integrity of the posterior vertebral cortex should be carefully evaluated preoperatively to prevent this complication.

Novel Modular Spine Blocks Affect The Lumbar Spine On Finite Element Analysis

Introduction

There are various surgical interventions to manage osteoporotic vertebral compression fracture. Modular spine block (MSB) is a novel intravertebral fixator that can be assembled. This study aimed to quantitatively investigate the force distribution in vertebrae with the various structural designs and implantation methods by finite element analysis (FEA).

Methods

A three-dimensional nonlinear FEA of the L3 implanted with MSB was constructed. Different structural designs (solid vs. hollow) and implantation methods (three-layered vs. six-layered and unilateral vs. bilateral) were studied. The model was preloaded to 150 N-m before the effects of flexion, extension, torsion, and lateral bending were analyzed at the controlled ranges of motion of 20°, 15°, 8°, and 20°, respectively. The resultant intervertebral range of motion (ROM) and disk stress as well as intravertebral force distribution were analyzed at the adjacent segments.

Results

The different layers of MSB provided similar stability at the adjacent segments regarding the intervertebral ROM and disk stress. Under stress tests, the force of the solid MSB was shown to be evenly distributed within the vertebrae. The maximum stress value of the unilaterally three-layered hollow MSB was generally lower than that of the bilaterally six-layered solid MSB.

Conclusions

The MSB has little stress shielding effect on the intervertebral ROM and creates no additional loading to the adjacent disks. The surgeon can choose the appropriate numbers of MSB to fix vertebrae without worrying about poly(methyl methacrylate) extravasation, implant failure, or adjacent segment disease.

A Spine Robotic-Assisted Navigation System for Pedicle Screw Placement

Pedicle screw implantation has excellent treatment effects and is often used by surgeons in spinal fusion surgery. However, due to the complexity of human body anatomy, this surgical procedure is difficult and challenging, especially in minimally invasive surgery or patients with congenital anomalies and kyphoscoliosis deformity. In addition to the abovementioned factors, the surgical experience and technique of the surgeon also affect the recovery rates and complications of the patients after the surgical operation. Therefore, accurately performing pedicle screw implantation has is a constant topic of common concern for surgeons and patients. In recent years, with the technological development, robot-assisted navigation systems have gradually become adopted. These robot-assisted navigation systems provide surgeons with complete preoperative planning before surgery. The system provides 3D reconstructed images of each vertebra, allowing surgeons to understand the patient's physiological characteristics more quickly. It also provides 2D images of sagittal, coronal, axial and oblique planes so that surgeons can accurately perform pedicle screw placement plan. Previous studies have demonstrated the effectiveness of robot-assisted navigation systems for pedicle screw implantation procedures, including accuracy and safety assessments. This step-by-step protocol aims to outline a standardized surgical technique note for robotic-assisted pedicle screw placement.

Reduction of the domino effect in osteoporotic vertebral compression fractures through short-segment fixation with intravertebral expandable pillars compared to percutaneous kyphoplasty: a case control study

Background

Osteoporotic vertebral compression fracture is the leading cause of disability and morbidity in elderly people. Treatment of this condition remains a challenge. Osteoporotic vertebral compression fractures can be managed with various approaches, but each has limitations. In this study, we compared the clinical outcomes obtained using short-segment fixation with intravertebral expandable pillars (I-VEP) to those obtained with percutaneous kyphoplasty in patients who had suffered vertebral compression fractures.

Methods

The study included 46 patients with single-level osteoporotic thoracolumbar fractures. Twenty-two patients in Group I underwent short-segment fixation with I-VEP and 24 patients in Group II underwent kyphoplasty. All patients were evaluated pre- and postoperatively using a visual analogue scale, anterior height of the fractured vertebra, and kyphotic angle of the fractured vertebra. The latter 2 radiological parameters were measured at the adjacent segments as well.

Results

There was no significant difference between the groups in terms of gender or fracture level, but the mean age was greater in Group II patients (p = 0.008). At the 1-year follow-up, there were no significant differences in the visual analogue scale scores, anterior height of the fractured vertebra, or the value representing anterior height above the fractured vertebra and kyphotic angle below the fractured vertebra, after adjusting for the patients’ gender, fracture level, and age. When considered separately, the anterior height below the fractured vertebra was significantly higher and the kyphotic angle above the fractured vertebra was significantly smaller in Group I than in Group II (p = 0.029 and p = 0.008, respectively). The kyphotic angle of the fractured vertebra was significantly smaller in Group II than in Group I (p < 0.001).

Conclusions

In older individuals with vertebral compression fractures, kyphoplasty restored and maintained the collapsed vertebral body with less kyphotic deformity than that induced by short-segment fixation with I-VEP. Short-segment fixation with I-VEP was more effective in maintaining the integrity of adjacent segments, which prevented the domino effect often observed in patients with osteoporotic kyphotic spines.

Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire

Background

In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS).

Methods

Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed.

Results

The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(p < 0.0001), and increased to 18.4 ± 8.6°(p = 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (p = 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, p < 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical.

Conclusion

Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method.

The effects of intravenous zoledronic acid in Chinese women with postmenopausal osteoporosis

The aim of this study was to assess the efficacy and safety of a once-yearly zoledronic acid treatment for Chinese women with postmenopausal osteoporosis in Taiwan and Hong Kong. This post hoc subpopulation analysis, from the Health Outcome and Reduced Incidence with Zoledronic Acid One Yearly Pivotal Fracture Trial, enrolled 323 Chinese women with osteoporosis who were randomly given either annual infusions of zoledronic acid or placebo for 3 consecutive years. The incidence of fractures and changes in bone mineral density (BMD) were measured; adverse events (AEs) and tolerability were recorded and assessed. The results of this study at 36 months demonstrate that there was a significantly reduced risk of morphometric vertebral fracture and clinical vertebral fracture in subjects treated with zoledronic acid (P < 0.05). In addition, there were significant increases of BMD by 4.9%, 4.3%, and 7.0% in the total hip, femoral neck, and trochanter, respectively, in the zoledronic acid group compared with the placebo group (P < 0.001 for all comparisons). The incidences of AEs were comparable between the two groups. Thus, once-yearly zoledronic acid treatment showed bone protection effects by reducing the risk of vertebral fracture and increasing BMD in Chinese women with postmenopausal osteoporosis.

A comparison between pulsed radiofrequency and electro-acupuncture for relieving pain in patients with chronic low back pain

Many treatment options for chronic low back pain are available, including varied forms of electric stimulation. But little is known about the electricity effect between electro-acupuncture and pulsed radiofrequency. The objective of this study is to assess the difference in effectiveness of pain relief between pulsed radiofrequency and electro-acupuncture. Visual analog score (VAS) pain score, the Oswestry disability index (ODI) to measure a patient's permanent functional disability, and Short form 36 (SF-36) which is a survey used in health assessment to determine the cost-effectiveness of a health treatment, were used as rating systems to measure the pain relief and functional improvement effect of pulsed radiofrequency and electro-acupuncture, based on the methodological quality of the randomized controlled trials, the relevance between the study groups, and the consistency of the outcome evaluation. First, the baseline status before therapy shows no age and gender influence in the SF-36 and VAS score but it is significant in the ODI questionnaire. From ANOVA analyses, it is apparent that radiofrequency therapy is a significant improvement over electro-acupuncture therapy after one month. But electro-acupuncture also showed functional improvement in the lumbar spine from the ODI. This study provides sufficient evidence of the superiority of pulsed radiofrequency (PRF) therapy for low back pain relief compared with both electro-acupuncture (EA) therapy and the control group. But the functional improvement of the lumbar spine was proved under EA therapy only. Both therapies are related to electricity effects.

Vitamin-D binding protein does not enhance healing in rat bone defects: a pilot study

Vitamin D-binding protein (DBP) has an anabolic effect on the skeleton and reportedly enhances bone ingrowth. We used an in vivo critical bone defect model to determine whether local administration of DBP promotes bone defect healing. We created a 5-mm segmental bone defect in the radial shaft in a rat model. Forty-eight rats were assigned to eight groups: local application of 1 microg, 5 microg, 10 microg, or 50 microg DBP (DBP-1, DBP-5, DBP-10, DBP-50), autogenous bone marrow mononuclear cells with or without 10 microg DBP (BM-DBP-10, BM), 80 microg BMP-2 delivered in gelatin sponge (BMP-2), and the sham operated group. Radiographic evaluation, histological stains, and epifluorescence microscopy were performed. Grossly, all bone gaps of the BMP-2 group were solidly bridged by callus, while all those in the sham operated group remained unhealed by 9 weeks. Only one specimen of the BM-DBP-10 and DBP-50 groups and three specimens of the BM group were solidly healed; pseudarthroses occurred in all of the other specimens. Histological study and radiographs of the specimens showed similar results. We did not observe the enhanced bone healing reported in a previous study.

Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone

Background

This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws).

Methods

This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct.

Results

The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and R² = 0.93. On the other hand, the average error and R² value of the literature formula were as high as -32.3% and -0.26, respectively.

Conclusion

The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests.

Clinical outcomes of microendoscopic decompressive laminotomy for degenerative lumbar spinal stenosis

The goal of surgical treatment for degenerative lumbar spinal stenosis (LSS) is to effectively relieve the neural structures by various decompressive techniques. Microendoscopic decompressive laminotomy (MEDL) is an attractive option because of its minimally invasive nature. The aim of prospective study was to investigate the effectiveness of MEDL by evaluating the clinical outcomes with patient-oriented scoring systems. Sixty consecutive patients receiving MEDL between December 2005 and April 2007 were enrolled. The indications of surgery were moderate to severe stenosis, persistent neurological symptoms, and failure of conservative treatment. The patients with mechanical back pain, more than grade I spondylolisthesis, or radiographic signs of instability were not included. A total of 53 patients (36 women and 17 men, mean age 62.0) were included. Forty-five patients (84.9%) were satisfied with the treatment result after a follow-up period of 15.7 months (12-24). The clinical outcomes were evaluated with the Oswestry disability index (ODI) and the Japanese Orthopedic Association (JOA) score. Of the 50 patients providing sufficient data for analysis, the ODI improved from 64.3 +/- 20.0 to 16.7 +/- 20.0. The JOA score improved from 9.4 +/- 6.1 to 24.2 +/- 6.0. The improvement rate was 73.9 +/- 30.7% and 40 patients (80%) had good or excellent results. There were 11 surgical complications: dural tear in 5, wrong level operation in 2, and transient neuralgia in 4 patients. No wound-related complication was noted. Although the prevalence of pre-operative comorbidities was very high (69.8%), there was no serious medical complication. There was no post-operative instability at the operated segment as evaluated with dynamic radiographs at final follow-up. We concluded that MEDL is a safe and very effective minimally invasive technique for degenerative LSS. With an appropriate patient selection, the risk of post-operative instability is minimal.

Instrumented posterior lumbar interbody fusion in adult spondylolisthesis

It is unclear whether using artificial cages increases fusion rates compared with use of bone chips alone in posterior lumbar interbody fusion for patients with lumbar spondylolisthesis. We hypothesized artificial cages for posterior lumbar interbody fusion would provide better clinical and radiographic outcomes than bone chips alone. We assumed solid fusion would provide good clinical outcomes. We clinically and radiographically followed 34 patients with spondylolisthesis having posterior lumbar interbody fusion with mixed autogenous and allogeneic bone chips alone and 42 patients having posterior lumbar interbody fusion with implantation of artificial cages packed with morselized bone graft. Patients with the artificial cage had better functional improvement in the Oswestry disability index than those with bone chips alone, whereas pain score, patient satisfaction, and fusion rate were similar in the two groups. Postoperative disc height ratio, slip ratio, and segmental lordosis all decreased at final followup in the patients with bone chips alone but remained unchanged in the artificial cage group. The functional outcome correlated with radiographic fusion status. We conclude artificial cages provide better functional outcomes and radiographic improvement than bone chips alone in posterior lumbar interbody fusion for lumbar spondylolisthesis, although both techniques achieved comparable fusion rates.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Three-dimensional culture of human nucleus pulposus cells in fibrin clot: comparisons on cellular proliferation and matrix synthesis with cells in alginate

Regeneration of nucleus pulposus (NP) tissue may stop or reverse early intervertebral disk (IVD) degeneration. Cellular proliferation and matrix synthesis can be promoted by incorporation of cells and bioscaffolds. However, insertion of preshaped solid bioscaffolds may damage remaining IVD integrity. Fibrin clots can be introduced in a minimally invasive manner with polymerization in desired three-dimensional shape and retention of cells. In this study, we investigated the cellular proliferation and matrix synthesis of human NP cells in the fibrin clots in vitro. Monolayer-expanded cells were embedded in fibrin clot or alginate and were cultivated in vitro for 2 weeks. Increased DNA content and decreased expression of apoptosis stimulating fragment (Fas)-associated death-domain protein in fibrin scaffolds suggested higher cellular proliferation and reduced apoptosis. Superior proteoglycan synthesis was found in fibrin scaffolds. As expression of collagens I and X increased and SOX9 expression decreased, fibrin scaffolds tended to promote fibrotic transformation and inhibit chondrogenesis. Adjustments of fibrin preparations are needed to make it more suitable for IVD regeneration.

Superior mesenteric artery syndrome complicating staged corrective surgery for scoliosis

Superior mesenteric artery syndrome (SMAS) is a rare complication following correction of scoliosis with either nonoperative or operative methods. If the patient diagnosed with this syndrome is not managed timely and adequately, mortality may result. We report two cases of SMAS complicating staged corrective surgery for scoliosis using modern segmental derotation instrumentation system. The aim of this report is to highlight the clinical presentations, laboratory findings, radiologic features, and management of the syndrome. The first patient had the syndrome after two-staged scoliosis surgery with halo traction between two stages, and the second patient after three-staged scoliosis surgery with halo traction between the first and second surgeries. The first patient responded well to conservative treatment. However, the second patient failed to respond to conservative treatment and needed a gastrojejunostomy operation to bypass the duodenal obstruction. Clinicians treating post scoliosis surgery patients should always have a high index of suspicion for this potential life-threatening condition. Early diagnosis will enable a multidisciplinary team approach to be initiated early to provide optimal care for the patient. Nutritional and fluid supplementation is mandatory during conservative treatment. The duration for trial of conservative treatment should not exceed 1 week.

Surgical removal of extravasated epidural and neuroforaminal polymethylmethacrylate after percutaneous vertebroplasty in the thoracic spine

Although extravasations of polymethylmetharylate during percutaneous vertebroplasty are usually of little clinical consequence, surgical decompression is occasionally required if resultant neurologic deficits are severe. Surgical removal of epidural polymethylmetharylate is usually necessary to achieve good neurologic recovery. Because mobilizing the squeezed spinal cord in a compromised canal can cause further deterioration, attempts to remove epidural polymethylmetharylate in the thoracic region need special consideration. A 66-year-old man had incomplete paraparesis and radicular pain on the chest wall after percutaneous vertebroplasty for osteoporotic compression fracture of T7. Radiological studies revealed polymethylmetharylate extravasations into the right lateral aspect of spinal canal that caused marked encroachment of the thecal sac and right neuroforamina. Progressive neurologic deficit and poor responses to medical managements were observed; therefore, surgical decompression was performed 4 months later. After laminectomy and removal of facet joints and T7 pedicle on the affected side, extravasated polymethylmetharylate posterior and anterior to the thecal sac was completely removed without retracting the dura mater. Spinal stability was reconstructed by supplemental spinal instrumentation and intertransverse arthrodesis with banked cancellous allografts. Myelopathy and radicular pain gradually resolved after decompression surgery. The patient was free of sensory abnormality and regained satisfactory ambulation two years after surgical decompression.

All Pedicle Screw Fixation Technique in Correcting Severe Kyphoscoliosis in an Osteogenesis Imperfecta Patient

Spinal deformity in patients with osteogenesis imperfecta demonstrates a high prevalence. The surgical treatment of this problem had numerous difficulties, which included breakage of bone, dislodgement of implants, and late loss of correction. We reported the correction of severe kyphoscoliosis in a patient with osteogenesis imperfecta using 3-rod all pedicle screw fixation technique. In this case, the 2 main goals of spinal operation, stabilization and correction of spinal curvatures, were achieved. The Cobb angles of scoliosis and thoracic kyphosis were corrected from 110 degrees to 68 degrees and from 107 degrees to 39 degrees, respectively. One and a half years after the operation, spinal radiographs showed no loss of correction, either on coronal or sagittal planes. The predicted forced vital capacity, predicted forced expiratory volume in 1 second and vital capacity of the lung of the patient had improved 2-fold. The usage of pedicle screw, with its conical core and cylindrical thread design, and 3-rod technique in fixation, together with cyclic intravenous bisphosphonate administration and halo-gravity traction preoperatively, contributed to the success in this case.

Prognosis of operative treatment for metastatic hepatocellular carcinoma of the spine

Developing and developed countries have been reported increasing numbers of hepatocellular carcinoma and increased rates of distant metastasis from hepatocellular carcinoma. Data regarding operative treatments and prognoses of hepatocellular carcinoma metastasis to the spine are lacking in the literature. We retrospectively reviewed 12 patients with hepatocellular carcinoma and metastasis to the spine who had spinal surgery between 1986 and 1996. All 12 patients had severe back pain preoperatively. Posterior surgery alone was performed on two patients, anterior surgery alone in six patients, and combined anterior and posterior surgery in four. Ten of the 12 patients experienced pain relief and their neurologic status was preserved or improved. We designed a new outcome assessment, a modified Prolo scale, to evaluate surgical outcome. Seven of the 12 patients had good or excellent results. Our sample size was limited and we could draw no definite conclusions regarding the prognoses of these patients or the value of surgical intervention; however, we think that operative treatment for spinal metastatic hepatocellular carcinoma lesions may improve quality of life, regardless whether the survival time is prolonged.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series--no, or historical, control group). See the Guidelines for Authors for a complete description of levels of evidence.

An In-vitro Study on Regeneration of Human Nucleus Pulposus by Using Gelatin/Chondroitin-6-Sulfate/Hyaluronan Tri-copolymer Scaffold

Tissue engineering approaches for treating degenerative intervertebral discs aim to promote tissue regeneration then retard or even reverse the degenerative process. A gelatin/chondroitin-6-sulfate/hyaluronan tri-copolymer was developed to serve as a bioactive scaffold that could help human nucleus pulposus (NP) cells to preserve their cell viability/proliferation and promote matrix synthesis. Each scaffold was seeded with 1 x 10(6) monolayer-expanded human NP cells and then cultured in vitro. Over a 4-week cultivation period, cell-scaffold hybrids demonstrated active cell viability/proliferation and a progressive increase in net production of glycosaminoglycans. In comparison to monolayer cells, scaffold-cultured cells showed significantly higher mRNA expression in collagen II, aggrecan, Sox9, TGFbeta1, and TIMP1. Expression of mRNA was significantly suppressed in collagen I, collagen X, IL1, and Fas-associating death domain protein. Histological studies showed newly synthesized glycosaminoglycans deposits and collagen II in scaffolds. These results indicate that the tri-copolymer scaffold could be considered as a promising bioactive scaffold for regenerating human NP.

Postoperative meralgia paresthetica after posterior spine surgery: incidence, risk factors, and clinical outcomes

STUDY DESIGN

A prospective study on postoperative meralgia paresthetica after posterior thoracolumbar spine surgery on the Relton-Hall frame.

OBJECTIVES

To assess the incidence of postoperative lateral femoral cutaneous nerve (LFCN) neuralgia and to investigate its risk factors and clinical outcomes.

SUMMARY OF BACKGROUND DATA

Postoperative meralgia paresthetica is a common complication of posterior thoracolumbar spine surgery. The injury mechanism is external compression to the LFCN near the anterior superior iliac spine in the prone position.

METHODS

A total of 252 patients were examined for signs of meralgia paresthetica before and after surgery. Patients with a LFCN injury were followed regularly until sensory impairment resolved. Several possible contributing factors were assessed to evaluate the correlations.

RESULTS

Postoperative meralgia paresthetica was experienced by 60 patients (23.8%). Patients with an LFCN injury had a significantly greater body mass index (23.6 vs. 22.4 kg/m2) and a longer surgical time (3.7 vs. 3.2 hours). Overweight/obese patients had a significantly greater incidence (odds ratio, 1.83; 95% confidence interval, 1.02-3.29). Patients operated for degenerative spinal disorders also had a significantly higher incidence of LFCN injury (odds ratio, 2.81; 95% confidence interval, 1.53-5.13). Recovery took 10.5 days on average (range, 2 days to 2 months). Thirty-two patients (53%) recovered completely within the first week and every patient recovered within 2 months.

CONCLUSION

Postoperative meralgia paresthetica is a common but benign complication of posterior thoracolumbar spine surgery. Degenerative spinal disorders, overweight/obesity, and longer surgical time are factors related to a higher incidence of LFCN injury. The clinical outcome is always excellent, and complete recovery can be expected within 2 months.

Estimated prevalence of osteoporosis from a Nationwide Health Insurance database in Taiwan

Approximately 9.24% of the Taiwanese population is aged 65 years or older. Among them, osteoporosis is a major problem, along with it associated age-related fractures. We investigated the prevalence of osteoporosis in 1996-2001 by sampling Taiwan's National Health Insurance (NHI) database. Data from 102,763 men (51.27%) and 97,654 women (48.73%) were evaluated. In this cohort, osteoporosis was recorded in each yearly dataset if the codes 733.0 or 733.00-733.09 were found on a search of the administrative or outpatient sub-databanks. A stable estimated prevalence of osteoporosis was calculated according to Taiwan's NHI sampling data from 1999 to 2001. The results showed a trend toward increasing proportions of coded osteoporosis with age, more predominantly in the female population. The averaged prevalence of osteoporosis, between 1999 and 2001, in those aged > or = 50 years was 1.63% for men and 11.35% for women. These estimates were lower than those reported elsewhere for Taiwan and for Japan but more equal to that in the Mexican American sub-population of the United States. In conclusion, the prevalence of osteoporosis is underestimated in the NHI database. Policymakers should be aware of this finding and allocate resources accordingly.

Gelatin/chondroitin-6-sulfate copolymer scaffold for culturing human nucleus pulposus cellsin vitro with production of extracellular matrix

Tissue-engineering approaches for treating degenerative intervertebral discs aim to regenerate intervertebral disc tissues in order to retard or even reverse the degenerative process. This study was designed to investigate the feasibility of the glutaraldehyde crosslinked gelatin/chondroitin-6-sulfate copolymer scaffold to serve as a bioactive scaffold for culturing human nucleus pulposus (NP) cells in vitro with preservation of the cell viability, cell proliferation, and production of important extracellular matrix, including glycoaminoglycans (GAG) and Type II collagen. Each experimental sample was seeded with 1 x 10(6) human NP cells, and then the cell-scaffold hybrids were cultured in vitro for 6 or 12 weeks. SEM showed a highly porous structure with an average pore size of 100 microm in the copolymer scaffold. Immediately after cell seeding, SEM showed that the seeded cells penetrated deeply and distributed evenly in the copolymer scaffold. Water-soluble tetrazolium salt-1 (WST-1) assay showed good viability and active proliferation of cultured human NP cells in the copolymer scaffolds up to 12 weeks. The cell-scaffold hybrids contained significantly higher levels of sulfated GAG than the control samples (41.29 mug vs 6.04 mug per scaffold). Immunohistochemical study showed Type II collagen fibrils on the surface of scaffold substrate after 6 weeks of cultivation. More abundant deposition of Type II collagen could be detected after 12 weeks. The results achieved in this study indicate that the gelatin/chondroitin-6-sulfate copolymer scaffold is a promising bioactive scaffold for regeneration of nucleus pulposus tissue.

Multiple parallel skin markers for minimal incision lumbar disc surgery; a technical note

BACKGROUND

Spinal surgery depends on accurate localization to prevent incorrect surgical approaches. The trend towards minimally invasive surgery that minimizes surgical exposure and reduces postoperative pain increasingly requires surgeons to accurately determine the operative level before an incision is made. Preoperative localization with a C-arm image intensifier is popular, but the exposure of both patients and theatre staff to radiation is a disadvantage, as well as being time-consuming.

METHODS

We describe a simple surgical tool developed to help localize exact spinal levels in conjunction with a simple AP X-ray film immediately before surgery. Multiple parallel skin markers were made using a circular oven rack comprising multiple 1.5 cm spaced parallel wires attached to a circular outside rim. The longest line was placed on the line of the postero-superior iliac spine (PSIS) over the junction of the L5-S1 region.

RESULTS AND CONCLUSIONS

Based on the film taken, the incision can be accurately made at the intended level. The incision wound can be minimized to 3.0 cm even when using conventional disc surgery instruments.

Management of scoliosis

The etiology and nature of truncal deformity in idiopathic scoliosis remains unclear. Only 2 methods are effective to halt or correct the spinal deformity. The first is bracing in young patients and the second is surgical correction for severe curve. Bracing is feasible for children with a Cobb angle between 20 degrees to 35 degrees, while surgical correction is the only choice if the Cobb angle is greater than 40 degrees. Recent surgical developments have led to good correction results with reduced operative scale through continuous spinal cord monitoring, evolution of spinal implants, and better perioperative and postoperative care. The newer spinal systems can produce 3-dimensional reconstruction of the deformity and maintain truncal balance afterwards. The newer implants are user-friendly and low-profile. The combined hook/screw application (hybrid) and the all-screw placement methods have become quite popular. With these methods, the correction rate is increased with reduced loss of correction at follow-up. Navigation systems facilitate accurate insertion of pedicle screws into the vertebral bodies, while video-assisted endoscopic instruments allow early ambulation. These methods are useful in cases of thoracic scoliosis. In the future, in order to minimize the operative scale and prevent deformity, important goals are elucidation of the real nature and the causes of scoliosis and restriction of the number of fusion levels by use of emerging technologies.

[Gene typing of merozoite surface protein 1 of Plasmodium falciparum isolates from Hainan Province]

OBJECTIVE

To identify the genotype of merozoite surface protein 1 (MSP1) of Plasmodium falciparum isolates from Hainan Province.

METHODS

Nested PCR was applied to amplify the MSP1 of Blocks 2 and 3 Plasmodium falciparum isolates from Hainan Province. Two allelic family representative gene fragments were sequenced.

RESULTS

From 36 out of 39 blood samples from Plasmodium falciparum patients, 44 gene fragments of blocks 2 and 3 of the MSP1 were amplified, of which the MAD20-type allele was dominant(75%). followed by K1-type allele. No RO33-type allele was found. The mixed infection rate of the two different allelic type was 19.4%. Sequence analysis showed that the sequences of MAD20- and K1-type isolates from Hainan Province were highly homologous to that of the MAD20 and K1 allelic prototypes.

CONCLUSION

Two principal allelic types of MSP1 gene, MAD20- and K1-type, exist in malaria endemic areas in Hainan Province, the MAD20-type being the dominant.

Proximal kyphosis after short posterior fusion for thoracolumbar scoliosis

Thoracolumbar idiopathic scoliosis usually is treated by anterior spinal fusion. However, short posterior spinal fusion that includes only the structural curve has been tried in a limited number of patients. The fusion may end cranially in the lower thoracic region and cause an increase in sagittal decompensation at the proximal junction. From July 1989 to July 1998, 14 patients were treated with thoracolumbar idiopathic scoliosis by short posterior spinal fusion. The lateral radiographs were evaluated preoperatively, immediately postoperative, and during followup. The focal kyphotic angle was used to examine the changes in focal sagittal alignment. A 10 degrees progression was defined as the radiographic criterion for the development of junctional kyphosis. Proximal junctional kyphosis occurred in six of the 14 patients, in which one patient needed revision surgery. In all six patients, the average preoperative lumbar lordosis was greater than 35 degrees, and decreased more than 10 degrees during surgery. In the five patients with a focal kyphotic angle larger than 10 degrees, four had proximal junctional kyphosis develop. According to the current findings, short posterior spinal fusion can be done only if the focal kyphotic angle proximal to the fusion is less than 10 degrees, and the lumbar lordosis must be preserved carefully during surgery.

Mechanical performance of the new posterior spinal implant: effect of materials, connecting plate, and pedicle screw design

STUDY DESIGN

A newly designed spinal implant was tested to evaluate multicycle stiffness and fatigue resistance.

OBJECTIVES

To investigate the effect of different materials, connecting plate, and pedicle screw design on the mechanical performance of the spinal implant.

SUMMARY OF THE BACKGROUND DATA

The addition of cross-linkages did not significantly increase implant compression/flexion stiffness, but accelerated fatigue failure at the rod junctions. Both Ti-6Al-4V spinal implants and the 316L stainless-steel counterparts have been used extensively for clinical cases; however, design factors establishing the proposed superiority of the Ti-6Al-4V implant for fatigue resistance have not, as yet, been extensively studied.

METHODS

Twenty implants with connecting plates (two materials by two screw designs by five implants) and five implants without connecting plates were assembled to UHMWPE blocks and cyclically loaded from 60 N to 600 N at a frequency of 5 Hz.

RESULTS

Failure sites for the tested prototypes were at the cephalic screw hubs or rod-plate junctions. All Ti-6Al-4V implants demonstrated reduced stiffness compared to the structurally identical 316L analogs. The use of connecting plates raised the stiffness of the 316L prototypes without cross-links. However, elimination of the connecting plate avoided stress concentration at the rod/plate junctions and increased fatigue life. The Ti-6Al-4V new system with the minimal notch effect at the screw hubs achieved greater fatigue resistance than its 316L counterpart. By contrast, enlargement of the inner-hub diameter resulted in greater gains for fatigue resistance than for stiffness, especially for Ti-6Al-4V variants.

CONCLUSIONS

Although Ti-6Al-4V was superior to 316L for endurance-limit properties, structural design of the Ti-6Al-4V implant dramatically affects fatigue resistance. This may explain the differences between existing studies and the current report, comparing fatigue life for implants made from these two materials. Our results reveal that Ti-6Al-4V must be carefully treated because of sensitivity to notch, with special consideration given to screw-hub design.

Surgical correction of postradiation spinal deformity

BACKGROUND

Radiation to the juxtaspinal area in children with malignant tumors induces the appearance of a postradiation spinal deformity (PRSD) with drastic progression during the growth spurt, so surgical correction is mandatory. Methods of surgical treatment depend on the age of the patient, and the type and size of the spinal deformity.

METHODS

A long-term retrospective survey of 6 patients receiving surgical management of kyphoscoliosis was conducted. The original tumors were 3 Wilms' tumors, 2 neuroblastomas, and 1 lymphoma. The mean length of time for tumor excision and subsequent radiation was 2.2 years. The total radiation dose averaged 3566 rad. The mean age at initial presentation was 6.1 years and that at spinal correction was 11.8 years. Single posterior surgery was performed in 3 cases, while the other 3 required anteroposterior correction due to severe deformity and scar contracture.

RESULTS

The curves of PRSD were concave toward the side irradiated, and the kyphotic component was more severely involved than was the scoliotic component. Four patients had favorable correction without curve progression. However, in the other 2 younger patients, due to thinness of their back, rigid angulation of the spine, poor bony stock, and medical comorbidity, spinal instrumentation was rather difficult. Postoperative pseudarthrosis and subsequent rod protrusion occurred with progressive kyphosis.

CONCLUSIONS

PRSDs consist of uncommon developmental vertebral anomalies, of which curved patterns occur in any combination, but most severely involve the presence of collapsing kyphosis and soft tissue contracture. Surgical correction may be less effective, especially if the children are skinny and have low bone stocks.

The postural stability control and gait pattern of idiopathic scoliosis adolescents

OBJECTIVE: The static postural equilibrium and gait patterns between idiopathic scoliotic (IS) patients and normal subjects were studied to verify the best method to identify the functional disability in IS patients. DESIGN: The static stability in six postures and gait patterns among normal subjects and IS patients were compared. BACKGROUND: Postural stability control and gait analysis are non-invasive methods to identify many diseases. However, the dysfunction of IS patients in postural stability control and gait pattern is not clear. The results of this research may lead to further understanding of the etiology of idiopathic scoliosis in the postural equilibrium influencing aspects. METHODS: Thirty IS patients and fifteen normal subjects were recruited for postural stability control test and gait analysis using the force plate and 3-D motion analysis system. RESULTS: The IS patients generally produced higher sway area, lateral sway, sagittal sway, and sway radius than normal subjects. The cadence is smaller in the IS patients, but the stance phase and stride phase are similar to normal subjects. CONCLUSIONS: The IS patients are poor in postural stability control but their gait pattern is similar to that of normal subjects. Standing with trunk at full flexion is the most effective position to identify the postural stability control of IS patient.

Spinal fractures and pseudoarthrosis complicating ankylosing spondylitis: MRI manifestation and clinical significance

PURPOSE

To analyze magnetic resonance (MR) patterns of fractures and pseudoarthrosis of the ankylosing spondylitic spine, and related changes in the dura and adjacent soft tissue.

MATERIALS AND METHODS

Sixteen patients with radiographically evident fractures or pseudoarthrosis of the spine were included. Each underwent MR studies. Ten patients among them underwent surgical operations.

RESULTS

Both transdiscal (n = 12) and transvertebral (n = 4) fractures were identified. The levels were located from T9 to L3. Five of 16 patients had pseudoarthrosis. The fractures or pseudoarthrosis had two patterns: low signal on T1-and high signal on T2-weighted images, and low signal on both T1-and T2-weighted images. Disruption of anterior longitudinal ligament (ALL) was identified in 14 patients. Seven patients had vertebral translation, all had disruption of the ALL. Dural adhesions were noted in five patients and manifested as linear epidural enhancements with triangular blunt edges.

CONCLUSION

MR patterns of ankylosing spondylitis are important in evaluating complications of fractures or pseudoarthrosis, as well as changes in dura, soft tissue, and ligaments.

Stress analysis of the distal locking screws for femoral interlocking nailing

In femoral locked nailing, the distal locking screws are vulnerable to mechanical failure. Biomechanical studies have shown that the stress on these screws is substantially affected by the fit of the nail in the medullary canal. In this study, a "closed form" mathematical model based on elastic beam-column theory was developed to investigate how the nail-cortical contact, which was simulated by a linear elastic foundation, affected the stress on the distal locking screws. Providing data for the model was a construct of a fractured femur with an intramedullary locked nail loaded by an eccentric vertical load. The stress on the locking screw was analyzed as a function of the distance from the fracture to the locking screw in the distal fragment under two situations: with and without nail-cortical contact in the distal fragment. With nail-cortical contact, the screw stress decreased as the length of nail-cortical contact and the distance between the distal locking screw and the fracture site increased, but this stress contrarily increased when the nail reached the femoral region at which the screw length increased. The screw stress was much higher without nail-cortical contact than with contact and continued to increase as the nail was inserted further. The mathematical model developed here can be a convenient means of rapid stress evaluation and parametric analysis for locked femoral nailing. It may be used to improve the design of interlocking nails and surgical technique.

The oxidative metabolism of circulating phagocytes in ankylosing spondylitis: determination by whole blood chemiluminescence

OBJECTIVE

Superoxide anion radicals within the human body are regarded as a major cause of inflammation. However, their role in the pathogenesis of ankylosing spondylitis (AS) has not been well identified. This study aimed at investigating the relation between AS and the oxidative metabolism of phagocytes in whole blood.

METHODS

24 patients with classic AS were examined to determine their clinical status; complete blood count, erythrocyte sedimentation rate (ESR), and C reactive protein (CRP) were determined, and levels of the superoxide anion radicals in the patients with AS and 21 healthy subjects were assessed by the ultraweak chemiluminescence method. Subsequently, the relation between this disease and phagocytes was examined by using N-formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol-12-myristate-13-acetate (PMA) stimulants.

RESULTS

In clinical assessments, patients with AS had abnormally raised serum CRP (>10 mg/l) and ESR (>15 mm/1st h) levels. In contrast with healthy subjects, patients with AS had significantly increased rates of superoxide anion radical production in their whole blood either in the resting state or with either fMLP or PMA stimulation. In addition, chemiluminescence maximum light intensity was significantly higher in patients with AS than in healthy subjects after fMLP or PMA stimulation.

CONCLUSIONS

Our results suggest that the phagocytes of patients with AS are partly activated in the resting state, and are sensitive to fMLP or PMA stimulation. The priming of phagocytes in the bloodstream is likely to be a causative factor in the onset of AS.

Effects of dihydroartemisinin on fine structure of erythrocytic stages of Plasmodium berghei ANKA strain

AIM

The fine structural changes of Plasmodium berghei ANKA strain after treatment with the dihydroartemisinin (DATM) were observed.

METHODS

DATM 180 mg.kg-1.d-1 was given ig to outbreed NIH mice infected with P. berghei ANKA strain. Blood samples were collected, embedded and examined by electron microscopy.

RESULTS

In P. berghei ANKA strain, 1 h after drug administration, the parasites food vacuole membranes were destroyed, and the pigment grains showed some changes. The nucleus membrane, cytomembrane, and food vacuole membranes were stratified 2 h after administration. At the same time, swelling and separation of the outer and inner membrane or shrinking of the mitochondria were seen. Stripped nuclear and cytoplasm membrane were developed and vacuolizations were seen 4 h later. Eight hours after administration, a large number of parasite structures were destroyed except for a few parasite autophagic vacuoles.

CONCLUSION

DATM was a fast-acting and effective antimalarial drug. Its primary target is the membrane system. No obvious resistant characteristics were found upto 24 generations after resistant induction test for 4 months.

Oxidative injury induced by synthetic humic acid polymer and monomer in cultured rabbit articular chondrocytes

Humic substance has been proposed as one of the causative factors of Kashin-Beck disease (KBD), an endemic osteoarthritic disorder with necrosis of chondrocytes widely prevalent in some regions of China. In order to exclude the complications of natural humic substance, here we prepared phenolic polymers of synthetic humic acid (SHA) by oxidation of phenolic monomer, the protocatechuic acid (PCA). The biological effects of SHA and PCA on primary culture of rabbit articular chondrocytes were investigated. We found that not only SHA but also PCA caused chondrocyte injury, as evidenced by the loss of cell viability measured with methylthiazol tetrazolium (MTT) assay and the increased release of intracellular lactate dehydrogenase (LDH). Both SHA and PCA could result in lipid peroxidation and glutathione (GSH) depletion in chondrocytes, indicating that oxidative stress may be involved in chondrocyte injury. Furthermore, a marked increase in intracellular calcium level ([Ca2+]i) occurred after chondrocytes treated with SHA or PCA. These results suggest that chondrocyte injury elicited by SHA or PCA may be mediated through the occurrence of oxidative stress and the disruption of intracellular Ca2+ homeostasis. Data also suggest that the monomeric phenolic acid may be considered one of the causative factors of KBD in addition to humic substance.

Dose findings of dihydroartemisinin in treatment of falciparum malaria

Forty patients with uncomplicated P. falciparum malaria were respectively treated in an open randomized comparative study of dihydroartemisinin tablets given at total doses of 480 mg over 5 days and 640 mg over 7 days in a drug-resistant malaria endemic area in Hainan, China. The result showed that all patients were clinically cured. In 5-day and 7-day groups, the mean fever clearance times (FCT) were 26.1+/-10.2 and 21.1+/-11.8 hours respectively; the mean parasite clearance times (PCT) were 58.7+/-20.9 and 59.4+/-20.9 hours respectively, which showed no significant difference. 28-day follow-ups were accomplished on 39 and 37 cases respectively in two groups, the recrudescence rates were 20.5% (8/39) in 5-day group, while 2.7% (1/37) in 7-day group with significant difference (chi2=4.19, p<0.05). No clinical drug-related side effect was found in two groups during treatment.

Operative repair of symptomatic spondylolysis following a positive response to diagnostic pars injection

From 1989 to 1996, 275 patients (245 male and 20 female) with back pain symptoms and spondylolysis of the lumbar spine were reviewed. All patients were evaluated by a protocol that included nonoperative treatment, bone scan, and pars injection. Only those whose symptoms failed nonoperative measures, showing negative bone scan and positive pars injection, were regarded as candidates for surgical management. Pars injection with Marcaine was done, and there were 93 cases with a positive response of reproducing symptoms and symptom relief. Patients then received autogenous bone grafting and internal fixation of the pars interarticularis defect. The internal fixation devices used included translaminar screws (AO 3.5 cancellous screw) for the most frequent level of L5, hook screws for levels above L4, and augmentation with wire for cases with concomitant spinal bifida occulta. The average age of the surgical group (85 male and 8 female) was 23 years (range: 19-35 years). After a follow-up averaging 30.4 months (range: 24-48 months), fusion results were 87%. Clinical results of 85 cases (91.3%) were excellent to good; 8 cases were fair; there were no poor cases. Direct repair of the pars defect by internal fixation and bone grafting was done to preserve involved motion segment and to prevent abnormal stresses at adjacent levels. These procedures seemed to be clinically effective.

In vitro and in vivo mechanical evaluations of plasma-sprayed hydroxyapatite coatings on titanium implants: the effect of coating characteristics

This study was undertaken to evaluate the effect of coating characteristics on the mechanical strengths of the plasma-sprayed HA-coated Ti-6Al-4V implant system both in vitro and in vivo. Two types of HA coatings (HACs) with quite different microstructures, concentrations of impurity-phases, and indices-of-crystallinity were used. In vitro testings were done by measuring the bonding-strength at the Ti-6Al-4V-HAC interface, with HACs that had and had not been immersed in a pH-buffered, serum-added simulated body fluid (SBF). The shear-strength at the HAC-bone interface was investigated in a canine transcortical femoral model after 12 and 24 weeks of implantation. The results showed a bonding degradation of approximately 32% or higher of the original strength after 4 weeks of immersion in SBF, and this predominantly depended on the constructed microstructure of the HACs. After the push-out measurements, it was demonstrated that the HACs with higher bonding-strength in vitro would correspondingly result in significantly higher shear-strength at each implant period in vivo. Nevertheless, there were no substantial histological variations between the two types of HACs evaluated. The most important point elucidated in this study was that, among coating characteristics, the microstructure was the key factor in influencing the mechanical stability of the HACs both in vitro and in vivo. As a consequence, a denser HAC was needed to ensure mechanical stability at both interfaces.

Triple innominate osteotomy and rotational acetabular osteotomy in the treatment of congenital hip dysplasia

Congenital hip dysplasia is a developmental disease which predisposes patients to osteoarthritis of the hip. We compare the results and complications of triple innominate osteotomy and rotational acetabular osteotomy in the treatment of this disease. Between 1984 and 1992, 27 patients with 30 dysplastic hips received reconstructive procedures at National Taiwan University Hospital. Fourteen patients (16 hips) with a median age of 18 years were treated by triple innominate osteotomy. Nine of 16 hips had concomitant femoral osteotomy. Another 13 patients (14 hips) with a median age of 24 years were treated by rotational acetabular osteotomy. We compared the radiologic and functional results, complications and satisfaction of the patients in these two groups. Patients who underwent rotational osteotomy showed more correction in roof obliquity than patients who had triple innominate osteotomy. The functional results when evaluated by Harris scores, were better in patients who had triple innominate osteotomy than rotational osteotomy. Complications included one resubluxation of the hip in each group as well as one perforation of the hip joint and one pin break and nonunion at the osteotomy site in the rotational osteotomy group. Patients who had triple innominate osteotomy were more satisfied with the results. With proper selection of patients and accurate performance of the procedure, both triple innominate osteotomy and rotational osteotomy may be used effectively for the treatment of congenital hip dysplasia. However, in our study, patients who underwent rotational osteotomy had better anatomic correction, while those who underwent triple innominate osteotomy had better functional results.

Management of rigid post-traumatic kyphosis

STUDY DESIGN

Rigid post-traumatic kyphosis after fracture of the thoracolumbar and lumbar spine represents a failure of initial management of the injury. Kyphosis moves the center of gravity anterior. The kyphosis and instability may result in pain, deformity, and increased neurologic deficits. Management for symptomatic post-traumatic kyphosis always has presented a challenge to orthopedic surgeons.

OBJECTIVES

To evaluate the surgical results of one stage posterior correction for rigid symptomatic post-traumatic kyphosis of the thoracolumbar and lumbar spine.

SUMMARY OF BACKGROUND DATA

The management for post-traumatic kyphosis remains controversial. Anterior, posterior, or combined anterior and posterior procedures have been advocated by different authors and show various degrees of success.

METHODS

One vertebra immediately above and below the level of the deformity was instrumented posteriorly by a transpedicular system (internal fixator AO). Posterior decompression was performed by excision of the spinal process and bilateral laminectomy. With the deformed vertebra through the pedicle, the vertebral body carefully is removed around the pedicle level, approximating a wedge shape. The extent to which the deformed vertebral body should be removed is determined by the attempted correction. Correction of the deformity is achieved by manipulation of the operating table and compression of the adjacent Schanz screws above and below the lesion.

RESULTS

Thirteen patients with post-traumatic kyphosis with symptoms of fatigue and pain caused by slow progression of kyphotic deformities received posterior decompression, correction, and stabilization as a definitive treatment. The precorrection kyphosis ranged from 30-60 degrees, with a mean of 40 degrees +/- 10.8 degrees. After correction, kyphosis was reduced to an average of 1.5 degrees +/- 3.8 degrees, with a range from -5 degrees to 5 degrees. The average angle of correction was 38.8 degrees +/- 10.4 degrees, with a range from 25 degrees to 60 degrees. Significant difference was found between pre- and post-operative kyphosis measures (P < 0.001). The follow-up period for all patients was 2 years, and the average kyphosis angle measured at the moment was 3.8 degrees +/- 3 degrees with a range from -3 degrees to 8 degrees. Substantial overall improvement was achieved in the 13 patients.

CONCLUSION

This method provides single-stage posterior decompression, correction, and stabilization on as definitive management for post traumatic kyphosis of the thoracolumbar and lumbar spine.

Magnetic resonance imaging of vertebral compression fractures

In this study, magnetic resonance imaging (MRI) was used to analyze the signal intensity and vascularity of compression fractures of vertebrae in 74 patients. The possibility of nonunion was assessed according to the specific image findings and clinical presentation. All patients had chronic back pain for more than 3 months and compression fractures of the vertebrae initially demonstrated by plain radiography. Pre-enhanced T1 and T2*-weighted images (*multiplaner gradient recall sequence) and postenhanced MRI were obtained. Images were divided into three categories according to the signal intensity of the fractured vertebrae such as hyperintensity (n = 35), hypointensity (n = 24) on T1-weighted image and necrotic type compression fractures of the vertebrae (n = 15). Of the 15 necrotic-type cases, 13 disclosed "fluid"-containing space at the collapsed vertebrae and two showed "air"-containing space at the vertebral body. We believe that these findings are pathognomonic signs of nonunion of the collapsed vertebrae. Surgical specimens were obtained from the four patients whose vertebrae showed necrosis and granulation tissue. After posterior spinal instrumentation, the collapsed vertebral body regained the height and presence of the open end-plate of the vertebra on postoperative lateral radiography. The superior capabilities of MRI offers useful criteria that make the diagnosis of nonunion in compression fractures of the spine possible. Thus, a space with "fluid" or "air" collection at the anterior aspect of a collapsed vertebra as well as strong enhancement with Gd-DTPA at the posterior aspect of the collapsed vertebra may be considered to be pathognomonic signs of nonunion of the fractured vertebra.

The center of ground reaction force during lifting

The center locations of the ground reaction force were estimated when subjects assumed upright and bending postures as well as when they lifted at low and high speeds. Ten subjects participated in this study and were instructed to assume two postures and to perform two liftings sequentially in a random order. The center locations of the ground reaction force were calculated using a Computerized Dyno Graphic system (INFOTRONIC). The center of the ground reaction force in the full bending posture had a more anterior location than it did in the upright standing posture. When measured during the lifting activity, the center of the ground reaction force shifted forward and then backward during the whole activity. The center location shifted to a more anterior location during high-speed lifting than it did during low-speed lifting.

The infectivity of gametocytes of Plasmodium falciparum from patients treated with artemisinin

Twenty-seven patients with gametocytes of Plasmodium falciparum (PF) were divided into groups A, B, and C. A daily dose of 1200 mg artemisinin was given for 5 days to group A, a state dose of 750 mg of mefloquine to group B and a single dose of 750 mg mefloquine combined with 45 mg primaquine to group C. After treatment, the gametocyte count was taken daily, and infectivity of the gametocytes to Anopheles dirus via membrane feeding was also studied. Results showed that in group A, the density of gametocyte and infectivity were significantly reduced on days 4, 7, 14 and 21 after treatment; In group B, the gametocytes were significantly reduced on days 7, 14 and 21 and infectivity was significantly cut down on days 14 and 21 after medication. In group C, gametocytes disappeared in 5 out of 9 patients with failure of infecting mosquitoes in all 9 patients on day 4 after treatment. These indicate that artemisinin can effectively influence the infectivity of gametocytes of PF. Artemisinin is much better in blocking the transmission of PF malaria than mefloquine.

[The infectivity of gametocytes of Plasmodium falciparum from patients treated with artemisinine]

27 patients with gametocytes of P. falciparum were divided into groups A, B and C. 1,200 mg of artemisinine was given as a daily dose for 5 days to group A, 750 mg of mefloquine plus 45 mg of primaquine as a single dose to group C. After medication, gametocyte count was observed daily in addition to the infectivity of gametocytes of P. falciparum to Anopheles dirus. In group A, the density of gametocytes and the infectivity were significantly reduced on days 4, 7, 14 and 21 during the study. In group B, the density of gametocytes was significantly reduced on days 7, 14 and 21 and the infectivity was obviously lowered on days 14 and 21 after medication. In group C, gametocytes disappeared in 5 out of 9 patients with the failure of infection to mosquitoes on day 4 after treatment. This indicates that artemisinine can effectively influence the infectivity of gametocytes of P. falciparum. Artemisinine is superior to mefloquine in blocking the transmission of P. falciparum malaria.

Experimental structural scoliosis in rabbits

Structural scoliosis was produced by purely posterolateral mechanical tethering of the spine with ligation of the scapula to the opposite pelvic bone in rabbits during the growing period. It is a simple and easy method without direct trauma to the spine. When the tethering force occurred discontinuously or only in the coronal plane by drawing of the scapula to the ipsilateral pelvic bone in 17 rabbits, spinal deformity could not be produced. The model provided evidence of biplanar deformity as one of the initial factors for the development of structural scoliosis.

Plate fixation for anterior cervical interbody fusion

From April 1989 to April 1990, 13 patients with cervical spinal fracture/dislocation, spondylosis or metastasis were treated at the respective hospitals. There were 4 women and 9 men whose ages ranged from 25 to 70 years (mean 45 years). All of them were treated with neural decompression, bone grafting and anterior spinal interbody fusion. All iliac crest or fibular bone grafts were anchored to the vertebral bodies with plates and screws. The clinical outcomes were evaluated retrospectively. The results showed that all had improvement of neurological symptoms and signs. The radiographic evaluation revealed satisfactory alignment and sound union of the cervical spine in all 13 patients. No serious complications were found except screw loosening in two instances without impairment of clinical results. We concluded that anterior cervical plates provide effective stabilization which is essential for good results. Furthermore, from this study and a review of the literature, we advocated that it was not necessary for the tip of the screws to reach or even penetrate the posterior cortex of the vertebral body.

Gait analysis after total knee replacement for degenerative arthritis

Using quantitative gait analysis and clinical evaluation, the functional results of 18 total knee replacement (TKR) in 13 patients who had osteoarthritis were evaluated. Nine knees each were replaced by Insall-Burnstein (I/B) posterior stabilized design or Miller-Galante (M/G) prosthesis. The former was fixed by cement and needed to sacrifice posterior cruciate ligament (PCL), while the latter was inserted without cement, and PCL could be reserved. The follow-up period ranged from 21 to 77 months. At the final follow-up, the overall functional knee score was 94.1 points (I/B 95.0 versus M/G 92.2). The average active knee flexion was 109.7 degrees (I/B 116.4 degrees versus M/G 102.9). For gait analysis, three cameras synchronized with 2 AMTI force plates were connected to the VICON system to provide kinetic and kinematic data during level walking. The data were compared with the non-operated side; and with younger subjects as normal control. They were supposed to possess normal knee functions. In patients after knee prosthesis, they tended to have slower velocity, shorter step length and less cadence. They also showed shorter swing and longer stance phases. In the M/G knee ground, the duration for double-limb support was longer, but shorter for single-limb support. The angles of knee flexion-extension of both prosthetic groups became narrower. Their ground reaction forces in both vertical and medio-lateral directions were larger than in the control groups, probably due to quadriceps dysfunction and subtle imbalance of the soft tissue-prosthesis complex around the joint.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical studies of the anterior spinal fixators after corpectomy in pigs

An unstable corpectomy porcine spinal model was created for the testing of anterior spinal fixators including: Kaneda device (KD), combination of Polster-Brinckmann prosthesis and Zielke implant (PBZ), and a new prototype device (CH). These spinal implants were examined in a one above/one below corpectomy model to determine the relative stiffness of each construct and the deformation of the adjacent discs under loading. The results indicated that the relative torsion and flexion stiffness were higher for the tested spines fixed with KD and CH. However, the relative compression stiffness of the tested spines was the same for all devices. The rigidity of the spinal constructs, which were measured around the corpectomy region showed the same tendency as above. However, the stiffness of CH and KD constructs were significantly higher than that of the PBZ construct under flexion and torsion. The difference in deformation of the upper and lower adjacent discs was not obvious among the intact spine and the spinal constructs with different devices. Clinical relevances: The corpectomy model represents a "worst case" scenario of spinal instability. In many conditions, spinal reconstructive surgery can restore axial compressive, torsional, and flexural rigidity to normal levels. These experimental conclusions apply to acute restoration of stability, rather than to rigidity after long-term cyclical loading. These three anterior fixators extended to only one cephalad level and one caudal level beyond the corpectomy defect. The new prototype device (CH) has a stability to the Kaneda device. The superior mechanical strength and simpler operative procedure of the new device provide for a potential clinical advantage in restoration of unstable spinal conditions.