Biomechanical comparison of different combinations of hook and screw in one spine motion unit--an experiment in porcine model.

BACKGROUND: The biomechanical performance of the hooks and screws in spinal posterior instrumentation is not well-characterized. Screw-bone interface failure at the uppermost and lowermost vertebrae is not uncommon. Some have advocated for the use of supplement hooks to prevent screw loosening. However, studies describing methods for combined hook and screw systems that fully address the benefits of these systems are lacking. Thus, the choice of which implant to use in a given case is often based solely on a surgeon's experience instead of on the biomechanical features and advantages of each device. METHODS: We conducted a biomechanical comparison of devices instrumented with different combinations of hooks and screws. Thirty-six fresh low thoracic porcine spines were assigned to three groups (12 per group) according to the configuration used for of fixation: (1) pedicle screw; (2) lamina hook and (3) combination of pedicle screw and lamina hook. Axial pullout tests backward on transverse plane in the direction normal to the rods were performed using a material testing machine and a specially designed grip with self-aligned function. RESULTS: The pullout force for the pedicle screws group was significantly greater than for the hooks and the combination (p < 0.05). However, no significant difference was found between the hooks and the combination (p > 0.05). CONCLUSIONS: Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation.

Retinal protection by fungal product theissenolactone B in a sodium iodate-induced AMD model through targeting retinal pigment epithelial matrix metalloproteinase-9 and microglia activity.

Age-related macular degeneration (AMD) is the leading cause of low vision and blindness for which there is currently no cure. Increased matrix metalloproteinase-9 (MMP-9) was found in AMD and potently contributes to its pathogenesis. Resident microglia also promote the processes of chronic neuroinflammation, accelerating the progression of AMD. The present study investigates the effects and mechanisms of the natural compound theissenolactone B (LB53), isolated from Theissenia cinerea, on the effects of RPE dysregulation and microglia hyperactivation and its retinal protective ability in a sodium iodate (NaIO3)-induced retinal degeneration model of AMD. The fungal component LB53 significantly reduces MMP-9 gelatinolysis in TNF-α-stimulated human RPE cells (ARPE-19). Similarly, LB53 abolishes MMP-9 protein and mRNA expression in ARPE-19 cells. Moreover, LB53 efficiently suppresses nitric oxide (NO) production, iNOS expression, and intracellular ROS levels in LPS-stimulated TLR 4-activated microglial BV-2 cells. According to signaling studies, LB53 specifically targets canonical NF-κB signaling in both ARPE-19 and BV-2 microglia. In an RPE-BV-2 interaction assay, LB53 ameliorates LPS-activated BV-2 conditioned medium-induced MMP-9 activation and expression in the RPE. In NaIO3-induced AMD mouse model, LB53 restores photoreceptor and bipolar cell dysfunction as assessed by electroretinography (ERG). Additionally, LB53 prevents retinal thinning, primarily the photoreceptor, and reduces retinal blood flow from NaIO3 damage evaluated by optic coherence tomography (OCT) and laser speckle flowgraphy (LSFG), respectively. Our results demonstrate that LB53 exerts neuroprotection in a mouse model of AMD, which can be attributed to its anti-retinal inflammatory effects by impeding RPE-mediated MMP-9 activation and anti-microglia.

Surgical treatment for giant cell tumor of the thoracolumbar spine.

BACKGROUND: Giant cell tumor (GCT) of the bone has historically been regarded as an extremely unpredictable bone tumor. The anatomical characteristics of spinal GCT still present challenges to surgeons. Controversy remains regarding the proper treatment of patients with grade III tumors. METHODS: Eleven patients with grade III GCT of the thoracolumbar spine were treated between 1992 and 2002 at a medical center by the authors. Three patients were initially treated at other institutions. Adjuvant radiotherapy was employed for local recurrence in these three patients. The other eight patients were initially treated with marginal excision. The site, size, and extent of each lesion dictated the surgical approach. RESULTS: Five patients had tumor recurrence. One patient, who received radiotherapy, had local relapse with malignant transformation and finally died due to disease-related complications. One patient had a recurrent tumor with multiple metastases throughout the lung. Neurological status, measured using the American Spinal Injury Association scale, of one patient was worse after undergoing the procedure than preoperatively and three patients showed improvement. The other seven patients were classified as with the same grade postoperatively. CONCLUSION: Wide excision of GCT of the thoracolumbar spine is difficult and there is a risk of neurological deficit and spinal instability. Meticulous marginal excision with associated reconstruction may obtain good local control and preserve functional spine. Early detection of recurrent GCT during intensive follow-up can allow for treatment using en bloc excision which has achieved favorable prognoses.

Transforaminal epidural steroid injection for discectomy candidates: an outcome study with a minimum of two-year follow-up.

BACKGROUND: The efficacy of epidural steroid injection for sciatica due to herniated disc is controversial. This study evaluates the therapeutic effect of an alternative technique that uses a modified approach of epidural steroid injection for the above mentioned disease. The aim was to determine whether this procedure can reduce the need of surgery among discectomy candidates. METHODS: Twenty-one eligible patients who had suffered from sciatica with unilateral symptoms for 2 to 24 months received injections of betamethasone in combination with xylocaine. The treatment outcome was evaluated by direct questioning and examination using the JOA score (the criteria for low back pain syndrome of Japanese Orthopaedic Association) before the procedure and at the final follow-up visit. The final analysis comprised 19 patients with a minimum of 24-month follow-up. RESULTS: The overall JOA score increased significantly from 14.26 +/- 3.25 before injection to 23.38 +/- 4.46 after injection showing improvement. In terms of subcategories, the JOA score for sciatica increased significantly from 0.69 +/- 0.48 before infection to 2.13 +/- 0.72 after injection and the JOA score for daily activity increased significantly from 7.44 +/- 2.16 before injection to 12.19 +/- 2.23 after injection). In the end, three treated patients received surgical decompression for intractable recurrent pain. CONCLUSIONS: Transforaminal epidural steroid injection is a relatively simple, effective and low-risk alternative to surgical decompression for the treatment of lumbar disc herniation in selected cases. The procedure significantly alleviates the severity of sciatica due to a herniated disc and improves the patient's daily activity; this reduces the need for surgical decompression.

Long-term results of disc excision for recurrent lumbar disc herniation with or without posterolateral fusion.

STUDY DESIGN: A retrospective study assessing the long-term outcomes of repeat surgery for recurrent lumbar disc herniation. OBJECTIVES: To evaluate the results of repeat surgery for recurrent disc herniation, and compare the results of disc excision with and without posterolateral fusion. SUMMARY OF BACKGROUND DATA: The outcomes of revision surgery varied owing to the mixed patient populations. The optimal technique for treating recurrent disc herniation is controversial. METHODS: The sample included 41 patients who underwent disc excision with or without posterolateral fusion, with an average follow-up of 88.7 months (range, 60-134 months). Clinical symptoms were assessed based on the Japanese Orthopedic Association Back Scores. All medical and surgical records were examined and analyzed, including pain-free interval, intraoperative blood loss, length of surgery, and postsurgery hospital stay. RESULTS: Clinical outcome was excellent or good in 80.5% of patients, including 78.3% of patients undergoing a discectomy alone, and 83.3% of patients with posterolateral fusion. The recovery rate was 82.2%, and the difference between the fusion and nonfusion groups was insignificant (P = 0.799). The difference in the postoperative back pain score was also insignificant (P = 0.461). These two groups were not different in terms of age, pain-free interval, and follow-up duration. Intraoperative blood loss, length of surgery, and length of hospitalization were significantly less in patients undergoing discectomy alone than in patients with fusion. CONCLUSIONS: Repeat surgery for recurrent sciatica is effective in cases of true recurrent disc herniation. Disc excision alone is recommended for managing recurrent disc herniation.

Computer-assisted fluoroscopic navigation of pedicle screw insertion: an in vivo feasibility study.

BACKGROUND: Accurate placement of pedicle screws is difficult. PATIENTS AND METHODS: We evaluated the feasibility and accuracy of pedicle screw insertion assisted by a real-time, 2-dimensional (2D) image-guided navigation system in 12 patients who underwent thoraco-lumbar and/or lumbar stabilization. 66 pedicle screws were inserted either by senior spine surgeons or residents. The accuracy of positioning of the screws was evaluated using postoperative plain radiographs and thin-cut CT. RESULTS: 61 of the 66 screws were inserted successfully. 5 screw insertions showed structural violations: 4 on the medial and 1 on the lateral pedicle wall. The accuracy was higher in the sagittal plane than in the axial plain. There was no difference between the surgical error rates caused by the senior surgeons and the residents. INTERPRETATION: Using computer-assisted 2D fluoroscopic image navigation, it is possible to achieve reliable and accurate pedicle screw insertion during low thoracic and lumbar spinal surgery.