Kinematic analysis of hip and knee rotation and other contributors to ballet turnout

Abstract

Turnout, or external rotation (ER) of the lower extremities, is essential in ballet. The purpose of this study was to utilise physical examination and a biomechanical method for obtaining functional kinematic data using hip and knee joint centres to identify the relative turnout contributions from hip rotation, femoral anteversion, knee rotation, tibial torsion, and other sources. Ten female dancers received a lower extremity alignment assessment, including passive hip rotation, femoral anteversion, tibial torsion, weightbearing foot alignment, and Beighton hypermobility score. Next, turnout was assessed using plantar pressure plots and three-dimensional motion analysis; participants performed turnout to ballet first position on both a plantar pressure mat and friction-reducing discs. A retro-reflective functional marker motion capture system mapped the lower extremities and hip and knee joint centres. Mean total turnout was 129±15.7° via plantar pressure plots and 135±17.8° via kinematics. Bilateral hip ER during turnout was 49±10.2° (36% of total turnout). Bilateral knee ER during turnout was 41±5.9° (32% of total turnout). Hip ER contribution to total turnout measured kinematically was less than expected compared to other studies, where hip ER was determined without functional kinematic data. Knee ER contributed substantially more turnout than expected or previously reported. This analysis method allows precise assessment of turnout contributors.

On the track of the ideal turnout: Electromyographic and kinematic analysis of the five classical ballet positions

“…The p-values of post-hoc test for differences between the groups and between the settings are shown in Table 6. The pairwise comparisons revealed significantly higher angle values (1) in lesser rotation group than greater rotation group for HER left, (2) for forward setting than backward setting in greater rotation group for HER, KER and FPA left, and in lesser rotation group for HER and KER. The comparisons showed also significantly higher bioelectrical activity values (1) in greater rotation group than lesser rotation group for rectus abdominis and gluteus maximus, (2) in lesser rotation group than greater rotation group for biceps femoris, adductor longus, tibialis anterior and fibularis longus, (3) for forward setting than backward setting in greater rotation group for rectus abdominis, lateral gastrocnemius and medial gastrocnemius, and in lesser rotation group for biceps femoris, semitendinosus, vastus lateralis, vastus medialis, lateral gastrocnemius, medial gastrocnemius and tibialis anterior, (4) for backward setting than forward setting in greater rotation group for erector spinae, sartorius and rectus femoris, and in lesser rotation group for erector spinae, gluteus maximus and sartorius.…”

“…The turnout (TO) or external rotation of lower extremities (LEs) is a major component of the classical ballet positions (CP) [1]. In the ideal first classical ballet position, the dancer adopts a straight standing posture with the feet and knees of both LEs turned out and pointing in opposite directions so that the longitudinal axes of the feet form a straight line [2,3].…”

“…Five classical ballet positions are the first technical tasks to be mastered during ballet education as their technical correctness is indispensable for a whole professional dance career [5,6]. Ballet teachers instruct students how to maintain ideal TO by giving them the following principles: (1) buttocks must be tightened to keep the hip external rotation (HER); (2) feet must be supinated so that their lateral border will be depressed and closely adhere to the floor while their medial arch is elevated; (3) toes must be relaxed and placed on the floor; (4) the center of the patella should be above the second toe [1]; (5) hip joints must not be flexed but held in neutral anatomical position; (6) thighs should be held together (only in the first classical ballet position); (7) abdominal and back muscles must be tightened and form the foundation for the HER [7].…”

“…Some researchers state that 50-70% of LE external rotation in TO comes from the hip, whereas the other 30-50% comes from the knee, lower extremity, ankle and foot [9,11,12]. On the other hand, Quanbeck et al [1] discovered that the hip joint contributes only to 29-43% of TO, the knee 21-41%, while other contributors constitute 29-45% of TO. The dancers with decreased HER may perform the socalled forced TO by excessive turning out of their knees, ankles and feet, which compensates for an insufficient range of motion (ROM) of the hip [8,[13][14][15][16][17].…”

Analysis of martial arts athletes’ goniometric indicators

“…Goniometric analysis of ballet movements was fulfilled by Quanbeck Amy E. et al [31]. They found higher angle value of rotation in comparison with available results.…”