Youssef Masharawi

STUDY DESIGN: Thoracolumbar facet orientations were measured and analyzed. OBJECTIVES: To establish a comprehensive database for facet orientation in the thoracolumbar vertebrae and to determine the normal human condition. SUMMARY OF BACKGROUND DATA: Most studies on facet orientation have based their conclusions on two-dimensional measurements, in small samples or isolated vertebrae. The amount of normal asymmetry in facet orientation is poorly addressed. METHODS: Transverse and longitudinal facet angles were measured directly from 240 human vertebral columns (males/females, blacks/whites). The specimens' osteologic material is part of the Hamann-Todd Osteological Collection housed at the Cleveland Museum of Natural History (Cleveland, OH). A total of 4,080 vertebrae (T1-L5) from the vertebral columns of individuals 20 to 80 years of age were measured, using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA). Data were recorded directly on computer software. Statistical analysis included paired t tests and analysis of variance. RESULTS.: Facet orientation is independent of gender, age, and ethnic group. Asymmetry in facet orientation is found in the thorax. All thoracolumbar facets are positioned in an oblique plane. In the transverse plane, all facets from T1 to T11 are positioned with an anterior inclination of approximately 25 degrees to 30 degrees from the frontal plane. The facets of T12-L2 are oriented closer to the midsagittal plane of the vertebral body (mean range, 25.89 degrees-33.87 degrees), while the facets of L3-L5 are oriented away from that plane (mean range, 40.40 degrees-56.30 degrees). Facet transverse orientation at the thoracolumbar junction is highly variable (approximately 80% with approximately 101 degrees and approximately 20% with 35 degrees). All facets are oriented more vertically from T1 (approximately 150 degrees) to L5 (approximately 170 degrees). The facet sagittal orientations of the lumbar zygoapophyseal joints are not equivalent. CONCLUSIONS.: Asymmetry in facet orientation is a normal characteristic in the thorax.

BACKGROUND: Professional drivers have been found to be at high risk for developing low back pain. However, the exact reasons are poorly understood. OBJECTIVES: To assess the prevalence of LBP among Israeli professional urban bus drivers, and evaluate the association between LBP in drivers and work-related psychosocial and ergonomic risk factors. METHODS: A total of 384 male full-time urban bus drivers were consecutively enrolled to this cross-sectional study. Information on regular physical activity and work-related ergonomic and psychosocial stressing factors was collected during face-to-face interviews. The prevalence of LBP was assessed using the Standardized Nordic Questionnaire. RESULTS: From the total cohort, 164 bus drivers (45.4%) reported experiencing LBP in the previous 12 months. Ergonomic factors associated with LBP were uncomfortable seat (odds ratio 2.6, 95% confidence interval 1.4-5.0) and an uncomfortable back support (OR 2.5, 95% CI 1.4-4.5). In the group of drivers with LBP, 48.5% reported participation in regular physical activities vs. 67.3% in the group without LBP (P<0.01). The following psychosocial stressing factors showed significant association with LBP: "limited rest period during a working day" (1.6, 1.0-2.6), "traffic congestion on the bus route" (1.8, 1.2-2.7), "lack of accessibility to the bus stop for the descending and ascending of passengers" (1.5, 1.0-1.5), and "passengers' hostility" (1.8, 1.1-2.9). CONCLUSIONS: Work-related ergonomic and psychosocial factors showed a significant association with LBP in Israeli professional urban bus drivers. Prevention of work-related stress, organizational changes targeted to reduce stressful situations, improvement in seat comfort, and encouraging regular sports activity need to be evaluated as prevention strategies for LBP in professional bus drivers.

This study was designed to characterize the vertebral body (VB) shape, focusing on vertebral wedging, along the thoracic and lumbar spine, and to look for shape variations with relation to gender, age, and ethnicity. All thoracic and lumbar (T1-L5) dissected vertebrae of 240 individuals were measured and analyzed by age, gender, and ethnicity. A 3D digitizer was used to measure all VB lengths, heights, and widths, and their ratios were calculated. This study showed that the VB size was independent of age or ethnicity. VB left lateral wedging was found in most vertebrae of most individuals, yet systematically was absent in six vertebrae (T4, T8-T9, T11, L3-L4) with a greater tendency in females than males ( approximately 92% vs. 86%). The VB was anteriorly wedged from T1 through L2 (peak at T7), nonwedged at L3, and posteriorly wedged at L4-L5 (peak at L5). VB width decreased from T1 to T4 and then increased toward L4-L5, so that the spinal configuration in the coronal plane resembled two pyramids of opposite directions, sharing an apex at T4. The inferior VB width was significantly greater than the superior width of both the same vertebra and the adjacent lower vertebra, indicating a trapezoidal shape of the VB and an inverted trapezoidal shape of the intervertebral space. In conclusion, these findings indicate that the human vertebra, in its normal condition, maintains its external dimensions with age, independent of gender or ethnic origin. Clinical and surgical implications of the unique thoracolumbar architecture are discussed.

BACKGROUND: Little data are available on changes that occur with age in joint range of motion in dancers and nondancers. HYPOTHESIS: In dancers, joint range of motion will increase with age, whereas it will decrease in nondancers, independent of the joint studied. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: The study population included 1320 female dancers, aged 8 to 16 years, who participated in different types of dancing classes (classical ballet, modern dance, jazz, etc) and 226 nondancers of similar age. Range of motion was measured for the hip, knee, ankle, foot, and spinal joints. RESULTS: The pattern of differences in range of motion with age varied in different joints and types of movement. (1) For combined ankle and foot plantar flexion (pointe), ankle plantar flexion, and hip external rotation, there was no change in range of motion in dancers, whereas range of motion diminished with age in the nondancers. (2) For ankle dorsiflexion, neither group showed any change with age, and range of motion was significantly greater in the nondancer group. (3) For knee flexion, hip flexion, and hip internal rotation, range of motion decreased with age in both groups. (4) For hip abduction, range of motion decreased with age in dancers and remained constant in the nondancers. (5) For hip extension, range of motion increased in both groups. (6) For lower back and hamstrings, range of motion increased among dancers with age and remained constant among nondancers. CONCLUSION: Dancers and teachers should realize that passive joint range of motion is unlikely to improve with age. Therefore, the major goal of a dancing program should focus on exercises that retain the natural flexibility of the dancers' joints rather than trying to improve them.

STUDY DESIGN: A descriptive computed tomography (CT) study of the ligamentum flavum (LF) thickness in individuals with normal and stenotic lumbar spines. OBJECTIVE: To establish standards for normal and pathologic range of LF thickness and its asymmetry as indicated in CT images and to examine its association with vertebral body size, age, and gender. SUMMARY OF BACKGROUND DATA: LF lines a considerable part of the posterior and lateral walls of the spinal canal and is a major role contributor to spinal canal stenosis. Due to methodologic deficiencies (e.g., small sample size, lack of control for vertebral body size, gender, and age), the normal range of LF thickness is still controversial. Furthermore, data on important aspect of LF thickness such as left-right differences are missing. METHODS: Two groups of individuals were studied. The first group included 65 individuals with lumbar spinal stenosis (LSS) (mean age: 66 +/- 9.7 years) and the second, 150 individuals (mean age: 52 +/- 19 years) without LSS-related symptoms. LF thickness was measured on CT images (Philips Brilliance 64), obtained from axial plane scan at the intervertebral disc level. Measurements were performed at the levels of L3-L4, L4-L5, and L5-S1. Analysis of variance and t test were carried out to evaluate the association between LF thickness and demographic factors. RESULTS: Absolute and relative LF thickness were significantly greater in the LSS group at the levels of L3-L4 and L4-L5 on both sides, compared to control group (P < 0.05). LF thickness was independent of gender (absolute and relative thickness). Even though LF thickness at all levels significantly increases with age, significant changes after the age of 60 occurred only at L3-L4. Significant asymmetry in LF thickness was found at L3-L4 (2.9 +/- 0.90 mm on the right vs. 2.76 +/- 0.90 mm on the left) and L5-S1 (3.42 +/- 1.1 mm on the right vs. 3.22 +/- 1.22 mm on the left) (P < 0.05). CONCLUSION: LF thickness is an age-dependent and gender-independent phenomenon. LF is significantly thicker on the right side. The borderline between normal and pathologic LF thickness should not be set at 4 mm.