The revised Tokuhashi score; analysis of parameters and assessment of its accuracy in determining survival in patients afflicted with spinal metastasis.

PURPOSE: To determine the significance of each parameter of the revised Tokuhashi score and identify which is associated with survival. BACKGROUND: Spinal metastases are common and can be a challenging medical issue. Treatment options depend on patients' prognosis. Many scoring systems in the literature help estimate prognosis, such as the Tokuhashi, revised Tokuhashi, and Tomita scoring systems. METHODS: A retrospective review of all patients from 2003 to 2012 treated for spinal metastases in one center was conducted. Imaging, pathology, and charts were reviewed to determine the modified Tokuhashi scores. Scores were then compared to the actual documented survival. Univariate and multiple regression analyses were used to assess the importance of each individual parameter and survival time. Linear regression was used to determine the relationship between the Tokuhashi score and weighted Tokuhashi score with survival time. RESULTS: A total of 126 patients were reviewed. All parameters in the revised Tokuhashi score were significantly associated with survival time except for primary site using univariate analysis. Only the number of spinal metastases and metastasis to major organs showed statistical significance when multiple variable analysis was used. CONCLUSION: A number of spinal metastases and metastasis to major organs were the most important predictors of actual survival. Modification to the score based on population characteristics would help better identify patients with spinal metastases that can benefit from surgery.

Development of a whole disc organ culture system to study human intervertebral disc.

STUDY TYPE: Basic science Objective: Low back pain is one of the most common health problems1 and is strongly associated with intervertebral disc degeneration, (IVD). Current treatments remove the symptoms without reversing or even retarding the underlying problem. Development of new therapy for the regeneration of the degenerative IVD is complicated by the lack of a validated long-term organ culture model in which therapeutic candidates can be studied. The object of this study was to develop, optimize, and validate an organ culture model for human IVD, allowing for the study of degeneration and the potential for regeneration of the human IVD. METHODS: From eleven donors, an average of 5-6 IVDs were obtained. Inclusion criteria were; age between 50 and 70 years old, no history of cancer, chemotherapy, diabetes, or liver cirrhosis. An x-ray of the harvested spine was done to assess the grade of degeneration. Three different methods for isolating the discs were studied: with bony endplate (BEP), without endplate (NEP), and with cartilage endplate (CEP). Discs were cultured for 4 weeks without external load, in Dulbecco's modified eagle media with glucose and fetal bovine serum (FBS). Four different combinations of concentrations of glucose and FBS were compared: low glucose-low FBS, low glucose-high FBS, high glucose-low FBS, and high glucose-high FBS.2 Short-term cultures (1 week) were performed to compare the cell viability of the three methods of isolating the discs. Swelling potential on NEP and CEP discs from the same donor were evaluated. After four weeks of culture, a 4 mm punch was taken from CEP discs and cell viability was evaluated using a live/dead assay with confocal microscopy. RESULTS: Analyzing the potential of swelling in CEP discs, there was an increase in volume to a maximum of 25% and retention of shape and morphology. Whereas in NEP discs, there was an excessive deformation and a two-fold time increase in volume than CEP discs. The cell viability in short-term cultures is around 40%-50% in the BEP model, 50%-60% in the NEP model and > 96% in the CEP model. BEP isolated discs show endplate necrosis that begins after 4 days of culture. Cell viability in CEP discs was evaluated at 4 weeks in three different areas of the disc: nucleus pulposus, inner annulus fibrosus, and outer annulus fibrosus. We found no difference in live cells (> 96%) between the four different concentrations of FBS and glucose (Table 1). [Table: see text] CONCLUSIONS: We have developed a novel method to isolate human IVDs and optimized the culture conditions. The CEP method has been proven to be superior to the previous models (NEP and BEP) in cell viability and maintaining physiologic swelling.3 In the long-term cultures, the CEP system maintained sufficient nutrient supply and high cell survival in all regions of the discs even with low concentrations of FBS and glucose. The availability of an intact disc organ culture system has a considerable advantage over the culture of isolated disc cells, as it maintains the cells in their unique microenvironment, making any response to catabolic or anabolic agents more physiologically relevant.

Porous titanium-nickel for intervertebral fusion in a sheep model: part 2. Surface analysis and nickel release assessment.

Porous titanium-nickel (PTN) devices represent an alternative to traditional cage implants. PTN materials possess an interconnecting network of pores with capillarity properties that may promote bone ingrowth, long-term fixation, and intervertebral fusion without the need for bone grafting. However, their considerable surface area and nickel content may elicit concerns over sensitization potential. Therefore, PTN surface corrosion and nickel release resistance must be carefully studied. To evaluate this possibility, a PTN interbody fusion device (IFD) was compared to a conventional nonporous cage made of TiAlV, a well-known biocompatible biomaterial, in a sheep model. PTN and TiAlV IFDs were inserted at two non-contiguous lumbar sites for 3, 6, and 12 months postsurgery. Their surface was then evaluated by scanning electron microscopy (SEM) combined with backscattered electron analysis (BSE). No evidence of surface corrosion was observed either pre- or postimplantation, regardless of device type. Dosage of nickel ions was also performed with the use of inductively coupled plasma-mass spectrometry (ICP-MS). Blood nickel levels were observed to be within acceptable levels at all postinstrumentation times. Nickel content in PTN-adjacent tissue, as well as in detoxification and remote organs, was equivalent both in PTN-treated and control sheep. Therefore, porous titanium-nickel demonstrated resistance to both in vivo surface corrosion and nickel ion release and compared very well with a conventional titanium implant in the course of a 12-month sheep study.

The effect of fibrin sealant on spinal fusions using allograft in dogs.

STUDY DESIGN: This study investigated the use of Tisseel (immuno [Canada], Toronto, Ontario) as an adjunct to allograft spinal fusion. Thirteen mongrel, dogs were fused bilaterally with morcellized graft from a separate dog. OBJECTIVES: To evaluate whether fibrin sealant had an effect on bone volume of fusion mass in allograft fusions of the spine. SUMMARY OF BACKGROUND DATA: Fibrin sealant has been promoted for use in many orthopedic applications. There is controversy about its effectiveness in augmenting bone graft healing. However, some surgeons make routine use of the sealant in augmentation of bone grafting procedures. METHODS: To test the usefulness of this material in augmenting allograft fusions, the authors carried out bilateral posterolateral fusions in 13 mongrel dogs. At surgery, 15 cm3 of allograft was placed into a posterolateral position at the L5-L6 region on both sides of the spine. Fibrin sealant (Tisseel) was allocated randomly to one side only. Fusion mass was tested 6 months after the initial operation by computed tomographic scan imaging and mechanical testing. RESULTS: A significantly smaller bone volume mass, as illustrated by computed tomographic measurement, was seen on the Tisseel side (P = 0.03). Biomechanical testing indicated that there was a trend for the Tisseel side to be stiffer than the untreated side, particularly at lower weights, but statistical significance was not achieved. Computed tomographic volumetric analysis showed that Tisseel-treated allograft led to a significantly smaller fusion volume. CONCLUSIONS: This study refutes the belief that Tisseel is a good material for accomplishing or augmenting intervertebral arthrodesis. Fibrin sealant significantly retards allograft fusion mass formation in dogs.

Predicting height from arm measurements.

Height measurement is required to standardize measures of physical capacity (e.g., pulmonary function) and to adjust drug dosage in the physically disabled. To estimate height in wheelchair-bound patients, we examined the relation of four different upper extremity measurements to height in 119 normal individuals aged 0.5-56 years. Regression analysis was performed for each of the following: (a) interacromioclavicular distance, (b) upper arm, (c) lower arm (cubit), (d) arm span; with height. Pearson correlation coefficients of 0.937, 0.967, 0.975, and 0.989, respectively, were obtained (accuracy +/- 5%, 90% confidence interval, for upper and lower arm measurements). We conclude that height can be predicted reliably from arm measurements.

Spinal cord tissue pressure during spinal cord distraction in dogs.

Spinal column distraction is a known cause of spinal cord injury. Laplace's law predicts that cord interstitial pressure will elevate during spinal cord distraction. To determine the significance of the Laplace predictions a series of in vitro and in vivo experiments examining spinal cord distraction were performed. In vitro experiments were carried out on 10 dog spinal cords in a specially designed distraction apparatus. These experiments verified the Laplace's law demonstrating a close correlation (R(avg) = 0.99) between the tension applied to the cord, and cord interstitial pressure. Cord interstitial pressure strain (elongation) curves show that initial elongation is accompanied by negligible elevations of cord interstitial pressure; the final 20% elongation being responsible for 80% of the elevation in cord interstitial pressure. In vivo experiments were carried out on five beta-blocked dogs. Significant elevations in cord interstitial pressure were obtained during stepwise spinal column distraction. Spinal cord blood flow and somatosensory evoked potentials were well maintained during distraction until cord interstitial pressure reached 47 mm Hg. At this point a simultaneous fall in spinal cord blood flow and somatosensory evoked potentials was noted. Release of the distracting force resulted in return of spinal cord blood flow, somatosensory evoked potentials, and cord interstitial pressure to baseline. The authors conclude that significant elevations in cord interstitial pressure occur with spinal cord distraction and that these cord interstitial pressure elevations are associated with a reversible ischemic response in the cord.

Spinal cord distraction: an in vitro study of length, tension, and tissue pressure.

Since the Scoliosis Research Society released a report on cord injury related to Harrington rod instrumentation for scoliosis, little has been published on the pathophysiology of this disorder. Dolan et al. (4) described diminished cord blood flow associated with spinal distraction in a cat model, but failed to demonstrate its cause. In this article, we describe a series of in vitro experiments performed on dog and sheep cadaver spinal cords. Controlled distractive forces were applied to spinal cords while monitoring both cord interstitial pressure and cord elongation. A close (Ravg = 0.986) correlation was noted between applied tensile forces and cord interstitial pressure. At 1,000-g loads, the average tissue pressure obtained was 29.5 cm H2O, ranging from 17 to 47 cm H2O. However, it was noted that the cord demonstrated nonlinear tensile elastic properties that appeared exponential in the range examined. These properties are consistent with those described for collagen-containing compounds. We conclude that spinal cord distraction is capable of generating cord tissue pressures that could cause a spinal cord compartment syndrome and thereby seriously impair spinal cord blood flow causing spinal cord injury.