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.

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.

Although Schmorl's nodes (SNs) are a common phenomenon in the normal adult population, their prevalence is controversial and etiology still debatable. The objective was to establish the spatial distribution of SNs along the spine in order to reveal its pathophysiology. In this study, we examined 240 human skeleton spines (T4-L5) (from the Hamann-Todd Osteological Collection) for the presence and location of SNs. To determine the exact position of SNs, each vertebral body surface was divided into 13 zones and 3 areas (anterior, middle, posterior). Our results show that SNs appeared more frequently in the T7-L1 region. The total number of SNs found in our sample was 511: 193 (37.7%) were located on the superior surface and 318 (62.3%) on the inferior surface of the vertebral body. SNs were more commonly found in the middle part of the vertebral body (63.7%). No association was found between the SNs location along the spine and gender, ethnicity and age. This study suggests that the frequency distribution of SNs varies with vertebra location and surface. The results do not lend support to the traumatic or disease explanation of the phenomenon. SNs occurrences are probably associated with the vertebra development process during early life, the nucleus pulposus pressing the weakest part of the end plate in addition to the various strains on the vertebrae and the intervertebral disc along the spine during spinal movements (especially torsional movements).

In the present study, we tried to determine the association between joint ranges of motion, anatomical anomalies, body structure, dance discipline, and injuries in young female recreational dancers. A group of 1336 non-professional female dancers (age 8-16 years), were screened. The risk factors considered for injuries were: range of motion, body structure, anatomical anomalies, dance technique, and dance discipline. Sixty-one different types of injuries and symptoms were identified and later classified into four major categories: knee injuries, foot or ankle tendinopathy, back injuries, and non-categorized injuries. We found that 569 (42.6%) out of the 1336 screened dancers, were injured.The following factors were found to be associated with injuries (P < 0.05): (a) range of motion (e.g. dancers with hyper hip abduction are more prone to foot or ankle tendinopathies than dancers with hypo range of motion; (b) anatomical anomalies (scoliotic dancers manifested a higher rate of injuries than non-scoliotic dancers); (c) dance technique (dancers with incorrect technique of rolling-in were found to have more injuries than dancers with correct technique); (d) dance discipline (an association between time of practice en pointe and injury was observed); and (e) early age of onset of menarche decreased risk for an injury. No association between body structure and injury was found. Injuries among recreational dancers should not be overlooked, and therefore precautionary steps should be taken to reduce the risk of injury, such as screening for joint range of motion and anatomical anomalies. Certain dance positions (e.g. en pointe) should be practised only when the dancer has already acquired certain physical skills, and these practices should be time controlled.

The aim of the present study was to assess the prevalence and types of injuries in 1336 young, non-professional female dancers (age 8-16 years) who participated in a descriptive mixed (cross-sectional/ longitudinal) cohort study. Previous and current injuries were diagnosed and later classified into seven major categories. Our results show that 569 (42.6%) of the dancers examined manifested an injury. Advanced age and increased exposure to dance yielded an equivalent increase in the prevalence of injured girls: from 1 of 10 girls in the 8-year-old age cohort (mean = 1.05 per 1000 h) to 1 of 3 girls in the 14-year-old age cohort (mean = 1.25 per 1000 h). Time elapsing between first and second injuries decreased with age. Among the youngest group of dancers (8-9 years) the most common injury was tendonitis (41%), while in adolescent dancers (14-16 years) knee injuries became the leading cause of complaints (33%). We conclude that young, non-professional dancers are at high risk of injury. Dancers who had been injured in the past were at higher risk for re-injury. Tendonitis in the foot or ankle joint was a common injury among the youngest dancers, while knee injuries were common among adolescent dancers. A routine screening of this dancer population by an expert in dance medicine will reduce the risk for an injury.