Musculoskeletal characteristics of the lower limbs of students at a vocational ballet institution - retrospective analysis of cross-sectional data.

BACKGROUND

The existing literature on pre-professional ballet students mostly reports on injury patterns, eating disorders, hormonal paramenters or other singular items whereas an overall description of anthropometric and orthopedic values of this particular study population can rarely be found. The aim of the present article was to anthropometrically and orthopedically describe the lower extremity of the typical vocational ballet student, establish a database and enable future comparisons.

METHODS

In this study, n = 606 students (414 female, 192 male) of a governmental institution for vocational ballet in Germany, between the ages of 5 and 22 (Mean ±SD: 13.9 ±3.5) were examined by an experienced orthopedist and dance physician.

RESULTS

The average passive external rotation of the hip (ER) was 60° (±7.5) and 43.5° (±11.3) for the internal rotation (IR). The calculated range of motion (ROM) was 103.3° (±10.4). The mean tibial torsion (TT) was 22.4° (±6.3). The average calculated turnout (ER + TT) was 83.3° (±9.9) per leg. The passive dorsiflexion (DF) of the ankle was 23.6° (±4.7) and 70.1° (±7.5) for plantarflexion (PF). 52.5% of the examinees showed a splay foot. The passive DF of the metatarsophalangeal (MTP) joint was 88.9° (±6.3) and 62.3° (±5.2) for PF. The Pearson's correlation coefficient for age was r =.237/0.302 (right/left) with hip ER, r= -.634/0.537 (right/left) with hip IR, r =.11 (both sides) with ankle PF and r = -.0.253/-0.264 (right/left) with MTP joint DF of the big toe.

CONCLUSIONS

The typical vocational ballet student of our study showed a large ROM for hip ER, ankle PF and MTP joint DF of the big toe. Students were more flexible than examinees of previous studies and often achieved ballet-specific ideal values. Hence, it is very likely that a ballet-specific selection favours the generally large ROMs found in the present study. The data collected over the long period of twenty years can be seen as a limitation of the present study, as students selected at the beginning of that period might be very different to selected students at the end it. Furthermore, this study measured passive joint range of motion only.