Schober Test and Its Modifications Revisited-What Are We Actually Measuring? Computerized Tomography-Based Analysis.

OBJECTIVE: Examine Schober test's (ST), Modified ST (MST), and Modified-Modified ST (MMST) surface markers' accuracy in spanning lumbar L1-S1 motion segments and repeatability related to actual patient anatomy as measured on sagittal CT scans. METHODS: The study included 25 patients of varying heights, weights, and gender without prior spinal surgery or deformity. Researchers assessed patients' CT scans for ST, MST, and MMST skin levels of the measured cephalic and caudal endpoints. RESULTS: The original ST failed to include at least one lumbar motion segment in all patients, omitting the L1-L2 motion segment in 17 patients and the L2-L3 in another eight. The additional cephalic length of the MST did not improve the inclusion of the actual L1-S1 components. The MMST measured 19 'patients' entire L1-S1 motion segments, reaching a 76% accuracy rate. WMST, measuring 16 cm (instead of MMST's 15 cm), improved the measurement significantly, measuring the L1-S1 motion segments in all cases (with 100% accuracy). CONCLUSION: ST and its modifications fail to span the L1-S1 motion segments and are thus prone to underestimating lumbar spine motion. This study shows that the WMST is much more accurate than previous modifications and is a better tool for evaluating lumbar spine motion.

Posterior-only correction of Scheuermann kyphosis using pedicle screws: economical optimization through screw density reduction.

INTRODUCTION: Posterior-only approach using pedicle screws' fixation has emerged as the preferred surgical technique for Scheuermann kyphosis (SK) correction. Insertion of multiple pedicle screws while increasing stability increases also the risk of complications related to screw malpositioning and surgical cost. The optimal screw density required in surgical correction of SK remains unclear. This study compares the safety and efficacy of low screw density (LSD) versus high screw density (HSD) technique used in posterior-only correction of SK. METHODS: Twenty-one patients underwent surgical correction of SK between 2007 and 2011 and were reviewed after a mean of 29 months. HSD technique (i.e., 100 % of available pedicles, averaged 25.2 ± 4 screws) was used in 10 cases and LSD technique (i.e., 54-69 % of available pedicles in a pre-determined pattern, averaged 16.8 ± 1.3 screws; p < 0.001) was used in 11 cases. Kyphosis correction was assessed by comparing thoracic kyphosis, lumbar lordosis and sagittal balance on preoperative and postoperative radiographs. Cost saving analysis was performed for each group. RESULTS: Preoperative thoracic kyphosis, lumbar lordosis and sagittal balance were similar for both groups. The average postoperative kyphosis correction was similar in both HSD and LSD groups (29° ± 9° vs. 34° ± 6°, respectively; p = 0.14). Complication occurred in four patients (19 %) in the HSD group and in two patients (9 %) in the LSD group (p = 0.56). Three patients required re-operation. Compared to HSD using LSD saves 4,200 pounds sterling per patient in hardware and 88,200 pounds sterling for the entire cohort. CONCLUSION: LSD technique is as safe and effective as HSD technique in posterior-only correction of SK. Implant-related cost could be reduced by 32 %.

Percutaneous sacroiliac joint arthrodesis: a novel technique.

STUDY DESIGN: Consecutive case series. OBJECTIVE: To report a new percutaneous sacroiliac joint (SIJ) arthrodesis technique utilizing a Hollow Modular Anchorage screw. SUMMARY OF BACKGROUND DATA: A variety of SIJ arthrodesis techniques have been reported in the established academia to treat intractable SIJ pain. None combines minimal surgical exposure, instrumented fixation, and bone grating. METHODS: We describe a new percutaneous SIJ arthrodesis technique for patients with intractable SIJ pain. Preoperative and postoperative Oswestry Disability Index (ODI), Visual Analog Scale (VAS) for pain, and postoperative subjective patients' satisfaction were assessed for all patients. Minimum 2 years follow-up is documented. RESULTS: Nine patients underwent SIJ arthrodesis with the new technique. The mean ODI value dropped from 59 (range: 34 to 70) preoperatively to 45 (range: 28 to 60) postoperatively (P

A study of the radiologic predictors of curve flexibility in adolescent idiopathic scoliosis.

STUDY DESIGN: A study of flexibility of 101 idiopathic scoliosis antero-posterior radiographs. OBJECTIVE: To discover if there are any parameters on plain antero-posterior radiographs that can predict the flexibility of scoliosis curves. SUMMARY OF BACKGROUND DATA: Previously the flexibility index, generated from fulcrum bending x-rays, has been shown to be an accurate measure of curve stiffness. METHODS: Five postulated predictors of flexibility, measured on 101 immediate preoperative scoliosis radiographs, were compared with the flexibility index generated from fulcrum bending radiographs. Correlation between the 5 parameters and flexibility index was studied. Further analysis was performed to assess the significance of curve location in prediction of flexibility. Linear regression analysis was used. RESULTS: Linear regression including all 5 predictors showed Cobb angle and age to be the only significant predictors of flexibility. When Cobb angle and age were analyzed with location (thoracic, thoracolumbar) this was also found to be a significant factor. CONCLUSIONS: Cobb angle, age, and curve location are useful predictors of flexibility on antero-posterior radiographs. This may aid preoperative planning in the out-patients department.