The performance demands of ballet are comparable to many highly competitive athletic pursuits. Although dancers are artists and not athletes, the athletic demands of dance choreography place the dancer at risk for injuries. Fifteen to 20 percent of dance injuries involve the foot. Chronic injuries tend to predominate as they are related primarily to the repetitive impact loading of the dancer’s foot on a relatively hard, unyielding surface: the dance floor.
Unlike the athlete, who often wears a shoe specially designed to stabilize the foot and absorb shock, the ballet dancer wears only a thin slipper or toe shoe. Therefore, the majority of the forces of impact in this setting must be absorbed by the lower extremities. It is the failure to effectively and efficiently absorb these forces that can lead to injury to structures about the foot. Factors that can contribute to this ineffective absorption of energy include anatomic variation, improper technique and, in some cases, fatigue.
Exploring Anatomical And Technique-Related Causal Factors
The single most important anatomic factor in classical ballet is proper turnout of the hip. Each of the five basic positions has a single common denominator: maximum external rotation of the hip. All ballet movements begin or end with one of these positions. The aspiring dancer who has the good fortune of ligamentous laxity may have greater potential for superior turnout than “tighter” dancers.
Dance students with poor “natural” turnout at the hip may compensate by forcing external rotation at the knee or the foot and ankle joints.
Rolling in, the equivalent of excessive pronation, is a technique employed by some dancers to compensate for inadequate external rotation at the hip. Rolling in involves eversion of the hindfoot with forced pronation of the midfoot and forefoot. The consequence of such a maneuver is excessive strain on the medial structures of the foot and ankle, and can lead to chronic injuries.
A cavus foot, with its inherent rigid midtarsal joints, can also present problems to the aspiring ballet dancer. The cavus foot absorbs energy poorly and often diverts forces to structures unaccustomed or poorly suited to absorb stress. Cavus feet are especially vulnerable to ligamentous strain, fasciitis and stress fracture.
A dancer is best off with a broad, square foot so the forces are shared equally by all the metatarsals running down to the ball of the foot. The Morton’s foot, with its shortened first and fifth rays, is prone to soft corns and fractures at the base of the second metatarsal. The splayfoot has metatarsus primus varus, which is usually accompanied by a hypermobile first ray. This foot has a tendency to pronate or roll in, and is often a precursor to hallux valgus and bunionettes.
While the normal range of motion in the first metatarsalphalangeal joint is 63 degrees of dorsiflexion and 37 degrees of plantarflexion, dancers must routinely have 90 to 100 degrees of dorsiflexion to allow a full relevé onto demi-pointe. This motion is usually obtained by dancing while the musculoskeletal system is forming so the joints can be molded. Unfortunately, there are some young dancers who never develop adequate motion in this important joint. These individuals will have a very difficult time dancing ballet or modern dance, and are better off studying jazz or tap.