Preliminary Results of Instantaneous Centre of Rotation Change after Thoracic Instrumentation in Adolescent Idiopathic Scoliosis Patients.

Introduction: The instantaneous centre of rotation (ICR) is the centre of motion with zero velocity where a rigid body moves in a particular plane. ICR, as a dynamic measurement, gives more accurate results in terms of quality and quantity of the vertebral motions compared to range of motion (ROM). We aimed to determine the effect of thoracic instrumentation on cervical movement of adolescent idiopathic scoliosis (AIS) patients who had undergone thoracic level instrumentation by measuring pre-operative and post-operative ICR change in a pilot study. Materials and methods: A total of 25 AIS patients were included in this study. C4-C5 and C6-C7 segmental ICR were determined by pre-operative and post-operative cervical flexion-extension radiographs. In addition, cervical sagittal parameters and global sagittal parameters were investigated. Results: There was no statistically significant change in ICR location post-operatively in both x and y coordinates at C4-C5 segment (p: 0.326 and p: 0.946, respectively) and C6-C7 segment (p: 0.209, p: 0.086, respectively). There was a positive correlation between LCL and C4-C5 ICR y coordinate (r: 0.481), but not with C6-C7 ICR y coordinate (r: -0.2, p: 0.398). T5-T12 kyphosis decreased (p: 0.002) and T1 pelvic angle (0.003), SVA (0.02) and sacral slope (0.049) increased significantly post-operatively. T1S was correlated with LCL (r: 0.595, p: 0.002), T5-T12 kyphosis (r: 0.423, p: 0.035), SVA (r: 0.658, p<0.001) and C2-C7 SVA (r: 0.416, p: 0.039). Conclusion: The ICR for cervical region was not changed post-operatively in AIS patients with thoracic instrumentation. There was no relationship found between the development of post-operative cervical kyphosis or lordosis and ICR, which represents the quality and quantity of intervertebral motion. The T1 vertebra plays a key role for cervical, thoracic, and global parameters interaction.

A new method for detecting pedicular wall perforation during pedicle screw insertion.

STUDY DESIGN: Sensitivity, specificity, and predictive value analyses of a method that can be used to detect pedicular wall perforation during pedicle screw insertion were assessed. OBJECTIVE: To determine the accuracy of observing the fatty material expelled during pedicle screw insertion for detecting pedicular wall perforations. SUMMARY OF BACKGROUND DATA: Although many methods for safe and accurate insertion of a pedicle screw are described, the rates of misplacement still are high, and complications may occur from improper placement of pedicle screws. Computer-assisted insertion techniques are reported to be very accurate, but these techniques are not yet commonly available. METHODS: In this study, 74 pedicle screw insertions were observed for the material expelled after drilling for the pedicle screw. The outflows of blood and fatty particles were recorded separately. The position of the pedicle screws after surgery was verified by computed tomography. The specificity, sensitivity, positive and negative predictive values, and kappa statistics were assessed. RESULTS: Visible fatty particles were observed during 51 pedicle screw insertions. The histologic analysis showed that the fatty particles were coming from the bone marrow of the corpus. For the observation of fatty particles in detecting perforations along the pedicle screw pathway, the specificity was 98%, the sensitivity 73%, the positive predictive value 84%, the negative predictive value 95%, and the kappa statistic 0.74. CONCLUSIONS: The observation of fatty particles in the blood that comes out after drilling for the pedicle screw may indicate that there is no perforation along the pedicle screw pathway. The observation is easy to perform and does not require any special instruments. Therefore, it can be used alone or in combination with other methods to improve the accuracy of pedicle screw insertion.

Chondrosarcoma of the spine: 1954 to 1997.

OBJECT: Primary chondrosarcoma of the spine is extremely rare. During the last 43 years only 21 patients with this disease were registered at The University of Texas M. D. Anderson Cancer Center. The purpose of this study was to examine the demographic characteristics, treatments, and outcomes of this set of patients. METHODS: Medical records for 21 patients were reviewed. Age, sex, race, clinical presentation, tumor histology, tumor location in the spinal column, treatments, surgical details, and response to treatment were recorded. Surgical procedures were categorized as either gross-total resection or subtotal excision of tumor. Neurological function was assessed using Frankel's functional classification. Time to recurrence and survival analyses were performed using the Kaplan-Meier method. The median age of patients was 51 years, with fairly equal gender representation. Eighteen patients underwent at least one surgical procedure for a total of 28 surgical procedures: seven radical resections and 21 subtotal excisions. Radiation therapy was used in conjunction with 10 of the 28 surgical procedures. The median Kaplan-Meier estimate of overall survival for the entire group was 6 years (range 6 months-17 years). Tumors recurred after 18 of the 28 procedures. Kaplan-Meier analysis revealed a statistically significant difference in the per-procedure disease-free interval after gross-total resection relative to subtotal excision (exact log rank 3.39; p = 0.04). The addition of radiation therapy prolonged the median disease-free interval from 16 to 44 months, although this was not statistically significant (exact log rank 2.63; p = 0.16). CONCLUSIONS: Our results suggest that gross-total resection of the chondrosarcoma provides the best chance for prolonging the disease-free interval in patients. Subtotal excision should be avoided whenever possible. Addition of radiation therapy does not appear to lengthen significantly the disease-free interval in this patient population.

Detection of Mycobacterium tuberculosis in formaldehyde solution-fixed, paraffin-embedded tissue by polymerase chain reaction in Pott's disease.

STUDY DESIGN: Twenty-five formaldehyde solution-fixed, paraffin-embedded tissue blocks from vertebral biopsy specimen materials with presumptive diagnosis of tuberculous spondylitis and nonspecific vertebral osteomyelitis were studied. OBJECTIVES: To evaluate the sensitivity and specificity of polymerase chain reaction in detecting Mycobacterium tuberculosis in formaldehyde solution-fixed, paraffin-embedded tissue samples from histologically proved tuberculous spondylitis. SUMMARY OF BACKGROUND DATA: Diagnosis of a mycobacterial infection is a long and tedious process; because of the slow growth rate of mycobacteria on solid media, identification and antibiotic sensitivity testing can take up to 10 weeks, but the sensitivity of culture can be as low as 50%. Direct microscopy is insensitive because clinical samples may contain only few organisms. Recently, polymerase chain reaction has been applied in the rapid amplification and identification of many organisms, including mycobacteria. METHODS: The DNAs were extracted from 25 paraffin-embedded tissue blocks. An insertion element IS 6110 (Integrated DNA Tec. Inc., Corrallville, IA), a DNA sequence unique to Mycobacterium complex (M. tuberculosis and the subspecies Mycobacterium bovis), was amplified by polymerase chain reaction. Polymerase chain reaction results were compared with those of Mycobacterium culture, acid-fast bacilli staining, and histologic findings. RESULTS: Polymerase chain reaction was positive in 18 cases of 19 tuberculous spondylitis. Three of the polymerase chain reaction test results were positive with concomitant negative culture and positive acid-fast bacilli staining. There were six chronic nonspecific infections, and polymerase chain reaction results were negative in five cases; in the single positive case, DNA amplification results remained positive even after three repeated tests. CONCLUSION: Polymerase chain reaction has a sensitivity of 94.7%, specificity of 83.3%, positive predictive value of 94.7%, and a negative predictive value of 83.3%. Accuracy was calculated as 92%.