Background Ballet dancers experience changes in body alignment in repeated practice to achieve the ideal turn-out position, and they have different alignments from that of the non-ballet dancers. However, no quantitative data have been reported to support their differences in lower extremity alignment (LEA).
Objective To compare differences in clinical measures of static LEA between female ballet students and female non-ballet students.
Design Descriptive and cohort study.
Setting Controlled laboratory setting.
Patients (or Participants) Eighty-four female ballet students and fifty-one female non-ballet students were recruited.
Interventions (or Assessment of Risk Factors)
Every participant read and signed the concert form that approved by the Institutional Reviews Board (IRB). The static LEAs were measured using four instruments, Height gage, 6’ and 12’ Goniometers, PALM inclinometer, and Bubble inclinometer.
Main Outcome Measurements Twelve static LEAs includeing leg-length, quadriceps angle, tibiofemoral angle, prone rearfoot angle, forefoot angle, tibial torsion, tibial varum, hip anteversion, pelvic tilt, standing quadriceps angle, standing rearfoot angle and navicular drop were measured.
Results Ballet students showed greater mean in tibial torsion (M diff =4.55, SE=.83, t (266)= 5.51, p=.000, 95% CI: 2.92 – 6.18), anterior-posterior pelvic tilt (M diff =1.93, SE=.46, t (228)= 4.10, p=.000, 95% CI: 1.00 – 2.86), and standing rearfoot angle (M diff =4.81, SE=.51, t (268)= 9.42, p=.000, 95% CI: 3.81 – 5.82) than non-ballet students. In contrast, ballet students had lesser mean than non-ballet students in tibiofemoral angle tibiofemoral angle (M diff =-1.05, SE=.31, t (268)=-3.39, p=.001, 95% CI: -1.64 – -0.44), prone rearfoot angle (M diff =-8.65, SE=.56, t (254.04)=-16.16, p=.000, 95% CI: -9.71 – -7.60), tibial varum (M diff =-2.52, SE=.23, t (159.90)=-10.98, p=.000, 95% CI: -2.96 – -2.06), hip anteversion (M diff =-11.47, SE=.72, t (156.15)=-15.87, p=.000, 95% CI: -12.90 – -10.04), and navicular drop (M diff =-4.45, SE=.42, t (182.22)=-10.44, p=.000, 95% CI: -5.29 – -3.61).
Conclusions Significant results from the alignment indicate that ballet movement and turn-out position may suggest changes in LEA, therefore, clinicians should consider these aspects while preventing and treating dancer injuries.