An analysis of the foot in turnout using a dance specific 3D multi-segment foot model.

INTRODUCTION: Recent three-dimensional (3D) kinematic research has revealed foot abduction is the strongest predictor of standing functional and forced turnout postures. However, it is still unknown how the internal foot joints enable a large degree of foot abduction in turnout. The primary purpose of this study was to use a dance specific multi-segment foot model to determine the lower leg and foot contributions to turnout that female university-level ballets use to accentuate their turnout. METHODS: Eighteen female dance students (mean age, 18.8 ± 1.6 years) volunteered for this study. Retro-reflective markers were attached to the dancers' dominant foot. Each dancer performed three repetitions of functional turnout, forced turnout and ten consecutive sautés in first position. Repeated measures ANOVA with Bonferroni adjustments for the multiple comparisons were used to determine the kinematic adjustments, hindfoot eversion, midfoot and forefoot abduction, navicular drop (i.e. lowering of the medial longitudinal arch) and first metatarsophalangeal joint abduction between natural double leg up-right posture and the first position conditions. RESULTS: Hindfoot eversion (4.6°, p < 0.001) and midfoot abduction (2.8°, p < 0.001) significantly increased in functional turnout compared to the natural double leg up-right posture. Thirteen dancers demonstrated increased first metatarsophalangeal joint (MTPJ) abduction in forced turnout, however no statistically significant increase was found. Navicular drop during sautés in first position significantly increased by 11 mm (p < 0.001) compared to the natural double leg up-right posture. CONCLUSION: Our findings suggest dancers do pronate, via hindfoot eversion and midfoot abduction in both functional and forced turnout, however, no immediate association was found between forced turnout and first MTPJ abduction. Foot pronation does play a role in achieving turnout. Further prospective research on in situ measures of the lower limb in turnout and injury surveillance is required to improve our understanding of the normal and abnormal dance biomechanics.

Lower-Leg and Foot Contributions to Turnout in University-Level Female Ballet DancersA Preliminary Investigation.

BACKGROUND: Turnout in ballet is produced through summation of the joint structure characteristics and ranges of motion at the hip, knee, ankle, and foot. Contributions of the hip joint to functional turnout in dancers have received extensive examination, whereas little is known about contributions from the knee, ankle, and foot. The aim of this study was to explore the nonhip components of turnout to dancers' functional turnout in first position by assessing passive external tibiofemoral rotation and active measures of foot pronation, ie, navicular drop and Foot Posture Index. METHODS: Nineteen female university-level dance students aged 16 to 19 years participated in this descriptive correlational study. External tibiofemoral rotation, navicular drop, Foot Posture Index, and functional turnout were measured for the participants' right and left legs. RESULTS: Regression analyses revealed a weak relationship between passive external tibiofemoral rotation and functional turnout. Correlation analysis revealed a moderate negative relationship between passive tibiofemoral external rotation and the Foot Posture Index in functional turnout. CONCLUSIONS: These findings suggest that the lower leg does contribute to dancers' overall position of functional turnout. However, current methods are not useful in predicting a dancer's lower-leg contribution and alignment in functional turnout in first position.

Radiographic Measurements of the Affected and Unaffected Feet in Patients with Unilateral Hallux Limitus A Case-Control Pilot Study.

BACKGROUND: Controversy exists regarding the structural and functional causes of hallux limitus, including metatarsus primus elevatus, a long first metatarsal, first-ray hypermobility, the shape of the first metatarsal head, and the presence of hallux interphalangeus. Some articles have reported on the radiographic evaluation of these measurements in feet affected by hallux limitus, but no study has directly compared the affected and unaffected feet in patients with unilateral hallux limitus. This case-control pilot study aimed to establish whether any such differences exist. METHODS: Dorsoplantar and lateral weightbearing radiographs of both feet in 30 patients with unilateral hallux limitus were assessed for grade of disease, lateral intermetatarsal angle, metatarsal protrusion distance, plantar gapping at the first metatarsocuneiform joint, metatarsal head shape, and hallux abductus interphalangeus angle. Data analysis was performed using a statistical software program. RESULTS: Mean radiographic measurements for affected and unaffected feet demonstrated that metatarsus primus elevatus, a short first metatarsal, first-ray hypermobility, a flat metatarsal head shape, and hallux interphalangeus were prevalent in both feet. There was no statistically significant difference between feet for any of the radiographic parameters measured (Mann-Whitney U tests, independent-samples t tests, and Pearson χ(2) tests: P > .05). CONCLUSIONS: No significant differences exist in the presence of the structural risk factors examined between affected and unaffected feet in patients with unilateral hallux limitus. The influence of other intrinsic factors, including footedness and family history, should be investigated further.

Analysis of dynamic angle of gait and radiographic features in subjects with hallux abducto valgus and hallux limitus.

BACKGROUND: Hallux abducto valgus and hallux limitus are two commonly encountered foot deformities causing altered structure and function of the first metatarsophalangeal joint and subsequent compensatory mechanisms. This study was undertaken to determine the relationships between these two deformities and transverse plane position of the foot, or angle of gait, and several radiographic angular and linear parameters with established reliability. METHODS: A convenience sample of 23 subjects with hallux abducto valgus, 22 subjects with hallux limitus, and 20 control subjects was used. Radiographic parameters were standardized weightbearing views and included lateral stressed dorsiflexion of the first metatarsophalangeal joint, composite, dorsoplantar, and lateral views. Angle of gait was obtained from powdered footprints recorded on paper. Two left and two right footprints identified on each trial were used to calculate angle of gait. RESULTS: The findings of the study suggest that an association between angle of gait and the presence of hallux abducto valgus or hallux limitus does not exist. Possible explanations may relate to the large variability of normal angle of gait, the need to identify factors extrinsic to the foot capable of affecting transverse plane orientation of the foot, and the addition of information relating to symptoms. CONCLUSIONS: In this study, the presence of hallux abducto valgus or hallux limitus did not correspond to an association with a particular angle of gait. Length and elevation of the first metatarsal were associated in subjects with hallux abducto valgus and hallux limitus.

Plantar pressure and radiographic changes to the forefoot after the Austin bunionectomy.

We describe the effects of the Austin bunionectomy on plantar pressure distribution and radiographic measurements in the forefoot in 31 subjects (44 feet) with mild-to-moderate hallux valgus deformity and 36 control subjects (36 feet). Plantar pressure measurements before and 24 months after surgery showed peak pressure beneath the hallux reduced to normal values. Peak pressure measurements beneath the first, second, and third metatarsal heads in hallux valgus feet were relatively unchanged after surgery and remained higher than normal values. The operation produced significant decreases in mean preoperative radiographic measurements of hallux abductus, metatarsus primus varus, and first metatarsal protrusion distance in these patients to below-normal values.

Plantar pressure and joint motion after the Youngswick procedure for hallux limitus.

The effects of the Youngswick osteotomy on plantar peak pressure distribution in the forefoot are presented for 17 patients (23 feet) with mild-to-moderate hallux limitus deformity and 23 control subjects (23 feet). During 2 years of follow-up, the operation produced a significant increase in the range of dorsiflexion of the first metatarsophalangeal joint in these patients, reaching near-normal values. Preoperative and postoperative measurements, using a pressure-distribution measurement system, show that peak pressure beneath the hallux and the first metatarsal head remained unchanged. However, peak pressure was significantly increased beneath the second metatarsal head and decreased beneath the fifth metatarsal head. These findings suggest that the foot functioned in a less inverted manner postoperatively. Compared with normal feet, hallux limitus feet demonstrated significantly higher peak pressure beneath the fourth metatarsal head preoperatively and postoperatively.