Do particular foot types (intrinsic factors) as well as extrinsic factors of training, flooring and footwear contribute to lower limb injuries in ballet dancers?

Title: Primary research question: To what extent do particular foot types pes planus, pes rectus and pes cavus (intrinsic factors), training, flooring and footwear (extrinsic factors) contribute to lower limb injuries in ballet dancers? The significance of foot type as a precursor for foot and lower limb injury in 47 ballet dancers professional and amateur is explored. Primary focus included intrinsic factors of foot types: pes planus, pes rectus, pes cavus which were measured in stance and First and Fifth ballet positions using 3 proxy measures: Calcaneal Bisection, Navicular Drop Test and the Foot Posture Index. Extrinsic factors focused on training intensity, ballet shoes and flooring. A model for injury prevention was designed for health practitioners and teachers of dance. One hundred and ten injuries were reported current or past, 79 injuries (pes planus), 4 (pes cavus), and 27 (pes rectus) with zero – 6 injuries per dancer, mean 2.75+/2.4. In First position, 43 dancers overpronated above the normal 3-degree level (31 left, 32 right) Fifth position, (34 left, 34 right). Flooring, fatigue and overtraining were reported as cause of injury. An exploratory ordinal regression analysis identified degrees of overpronation as key risk factors for injury. Method: A study sample (n=47) of 15 males and 32 female dancers, aged 14 to 29 years (mean 18.5 years), consisting of 6 amateur and 41 elite dancers with/without current injuries. Foot type was assessed using 3 proxy measures; the Navicular Drop Test, Foot Posture Index, and Calcaneal Bisection and postural movement (Calcaneal Bisection/NVDT). History of foot and leg injuries, training, age, gender, height and weight, footwear worn and flooring were collected by questionnaire in an interview setting for cross correlation between frequency, nature of injury and foot type / foot posture. Results: Calcaneal Bisection and NVDT showed 100% correlation. Forty dancers reported current and past injuries (86%), 7 dancers had no previous injury. Foot types were: pes planus (28 left and 26 right), pes rectus (15 left and right), pes cavus (4 left and 6 right). Two dancers had non-matching pairs of feet. All pes planus feet overpronated (male/female), 11/15 males had pes planus. Higher levels of pronation >1.4 cm (ND) saw higher numbers of injuries per dancer, particularly males (4-6 injuries). All pes planus feet overpronated.