Biomechanics of the Dancer’s Ankle and Foot

Original Editor - Carin Hunter based on the course by Michelle Green-Smerdon
Top Contributors - Carin Hunter, Jess Bell and Kim Jackson

Introduction

Assessing an injury in a ballet patient can be a daunting task. After gaining a basic understanding of the foot and ankle anatomy, applying the biomechanical principles will help form a clear picture of the treatment plan. Dancers spend the majority of their time in extreme positions, mostly planter and dorsiflexion of their ankle. If there is no clear understanding of the requirements for these positions and the demands incurred, compensation can occur up the kinetic chain resulting in pain and injury.

The “Ideal” Anatomy for a Ballet Foot

• Maximal plantarflexion in the talocrural joint
• Maximal dorsiflexion in the first metatarsophalangeal joint
• A medium arch
• The best foot shape for dance is a square foot with equal length of the first and second ray
• Straight toes
• Strong intrinsic and extrinsic muscles
• Maximum flexibility, control, strength and endurance
• Ideally a genetic aspect of some form of hypermobility

The "Ideal" Biomechanics for a Ballet Foot

• Ideal turnout, as a result of strong external hip rotators
• Strong flexible back
• Control and coordination of hypermobility
• Active stabilisation of the trunk
• Excellent ballet technique

Movements of the Foot and Ankle

Ankle

• Dorsiflexion
  • Required for plie
• Plantarflexion
  • Required for pointe work

Foot (excluding toes)

• Inversion
  • Excess inversion ends in Sickle foot
• Eversion
  • Excess eversion ends in Winged foot

Toes

• Dorsiflexion
• Plantarflexion
• Abduction
  • Often accompanies Dorsiflexion
• Adduction
  • Often accompanies Plantarflexion

The combination of movements across subtalar and tibiotalar joints causes supination and pronation.

Ankle ROM

The range of motion in the ankle joint is vital to the ballet dancer. If the ROM is not adequate, this can cause pain, compensation and injury.

Average ROM

The expected plantarflexion range of motion in an average human is 30-50 degrees, while the expected dorsiflexion range of motion with knee extension is 10 degrees. When the knee is flexed, the expected range of dorsiflexion is 20 degrees. This results in an average through range measurement of 40 - 70 degrees.

A ballet dancer will work towards a through-range measurement of 90 degrees, with some reports of up to 101 degrees in elite dancers.

Important Aspects to Consider with ROM

• Degree of winging when pointing
• 'Over the box' movement in a pointe shoe
• Releve height achieved

When a ballet dancer trains, due to the repetition of movements and the desire to be strong on pointe, most commonly the amount of dorsiflexion will decrease as the plantarflexion increases. This is a common progression as the dancer becomes more proficient in their discipline.

As the dancer moves up in their grading, they move from a demi pointe position into full pointe work. When this progression takes place, commonly an increase of ankle or foot pain will be observed.

A dancer has to be aware that the main hinge point in their foot has to be the ankle joint. This joint requires a full ROM while the smaller joints in the foot often have to remain in a locked position.

“Muscle strength deficits contribute to faulty mechanics, including increased ankle inversion/eversion compensation in an effort to get en pointe/maintain position, decreased stability once there, knuckling under and decreased plantarflexion range of motion to allow ideal positioning over body over toes”

Importance of Alignment

A strong, well-aligned foot supports the full alignment up the chain. Poor alignment is a major risk factor of foot and ankle injuries in all ballet dancers, recreational and professional. Good alignment is essential to improving control, strength and injury prevention in the ankle and foot

Good Alignment

• When en pointe and demi-pointe, our body weight is transferred down through the tibia to the talus.
• The talus forms a joint in front with the navicular bone, which in turn forms joints with the cuneiforms and with the 1st, 2nd and 3rd metatarsals and toes.
• Bodyweight should be more focused through the medial or inner three toes if the dancer is to transfer body weight forces correctly through footwear to the floor
• Ensuring that weight is taken through the 2nd metatarsal when moving through the foot or standing on demipointe/pointe will allow the 5 bones of the midfoot to “lock” ensuring a more stable foot to work with
• Engagement of deep external hip rotators as the turnout of the hip will lead to supination of the rearfoot (lifted arch position), which will also lock up the middle region of the foot.

In the “perfect” demipointe/pointe position, the centre of the ankle should be aligned with the dancer’s second toe.  One method that is relatively easy to use that can help both the teacher and dancer understand “right from wrong” alignment involves the use of a pen or marking pen.  The student is asked to locate and mark the mid point between the malleoli.  A straight line is then drawn between this mark and the midline of the second toe.  When standing on demipointe or pointe, this line should remain vertical.

Importance of alignment for calf strength development

Correct alignment of the foot, ankle, leg, hip and spine is essential for the correct engagement of muscles for the choreography.

The incorrect alignment of the foot, ankle, leg, hip and spine will result in the dancer trying to force, or “muscle” the movements and this can result in an overuse injury of muscles that are not designed for dancing. The consequences of this is constant stiffness and tightness around the hip joints, thighs and calves, which will require management.

Arches

There are 3 arches in the foot

1. Medial longitudinal
   1. designed to allow the foot to trespass uneven surfaces and absorb shock
2. Lateral longitudinal
   1. stability
3. Anterior transverse
   1. aids in support and shock absorption, stability and balance, especially in releve

These arches contribute to normal weight distribution, stability and distribution in dancing. The arches are formed by the tarsal and metatarsal bones. The shape allows them to act as a spring, bearing the weight of the body and absorbing the shock produced during dancing

The height of the arches is determined by the bone structure and influenced by muscles and the flexibility of ligaments. When referring to arches in a dancers foot, they are commonly described as:

1. High
2. Medium
3. Flat

A medium arch is considered ideal. It allows good shock absorption and allows flexibility with the ligaments not too tight as to restrict movement.

The importance of arches in ballet

As mentioned above, the arches of the foot are important for optimal function, but for a ballet dancer, there are interesting complications to irregular arches.

• Weak lateral longitudinal arch
  • Contributes to sickling and supination
• Weak and flattened medial longitudinal arch
  • Contributes to winging and pronation
• Pronounced medial longitudinal arch
  • Results in supination or rolling to the outside of the foot

Intrinsic foot muscles

The biggest role of the intrinsic foot muscles to a ballet dancer is to oppose the clawing effect of the long flexors of the toes. When toes are flexed at the metatarsal phalangeal joints, the action of the intrinsic muscles helps to keep the interphalangeal joints straight.

The plantarflexion of the ankle and footwork are assisted by the long flexors of the toes, in a well-pointed foot, while the actual flexion effect of the long flexors on the toes is counteracted by a strong action of the intrinsic muscles, keeping the toes straight in the pointed foot.

The intrinsic foot muscles can also help in maintaining the transverse arch. If the arch drops, pain can develop under the metatarsal heads

Plantar fascia

Another key structure is the plantar fascia which is a band of connective tissue that runs on the plantar or bottom surface of the foot. It acts as the main support for the medial longitudinal arch and, therefore, plays a key role in stabilizing the foot in action that requires pushing off the ground to propel such as jumping or running.

Turnout

Not every dancer has sufficient external rotation in the hips and inadvertently three types of compensatory mechanisms are used to mimic a better ‘turn-out’:      

1. Lower back
   1. Lumbar hyperlordosis, or swayback, while slightly flexing at the knees which results in anterior pelvic tilt and increased hip flexion with the relaxation of the anterior hip capsule (iliofemoral or Y-ligament)
2. Knees
   1. An extended knee is rigid, but bending the knees allows external rotation of the lower leg, but must grip the toes on the floor to maintain the position
3. Feet
   1. Hyper pronation, or ‘rolling-in’, gives the impression of additional turn-out by abduction of the forefeet. Once the desired turned-out position of the feet is achieved, the dancer ‘grasps’ the floor and ‘stretches up’ resulting in low back tension, increased torsion torque on the knees and stress on the medial side of the feet. This is an important source of dance injuries

Hyperpronation

• Hyperpronation or excessive pronation at the ankle joint can stretch the supporting ligaments and tendons of the medial aspect and plantar aspect of the foot. This can affect the medial arch which placed a strain on the extrinsic muscles as they try to support the arch.
• This places dancers at risk for medial tibial stress syndrome, flexor hallucis longus tendonitis, or plantar fasciitis. This may also lead to difficulty when resupinating the foot to go on pointe.
• As we look further up the chain, the complications of hyperpronation can contribute to patellofemoral pain syndrome (PFPS and retropatellar chondropathy (RPCP) from increased tibial torsion and lower back pain.

According to an article written by Nowacki et al, hyperpronation has  also been seen to contribute to the following conditions:

Non-contact anterior cruciate ligament (ACL) injuries

(medial) sesamoiditis,

Achilles tendonitis,

leg length discrepancy

stress fractures,

hallux valgus, and

Bunions