Key Biomechanical Insights For Treating Dance Injuries
- Volume 20 - Issue 6 - June 2007
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Technique. The patient is in a supine position with legs fully extended. The examiner crouches to eye level with the sagittal ankle. The examiner grasps the fifth metatarsal head and maximally extends the knee while locking the midtarsal (by exerting a dorsiflexion/eversion moment at the fifth metatarsal head). The examiner maintains a subtalar neutral position with gentle palpation by the opposite hand. (Note that forceful palpation elicits apprehensive active dorsiflexion and invalidates the exam.) With the patient at the end range of passive dorsiflexion, the examiner drops an imaginary plumb line, perpendicular to the leg’s long axis, from the plantar fifth metatarsal head down to the heel. The distance between the inferior heel nadir and plumb line is the DKE value.
When the patient has end range of motion with the fifth metatarsal head stopping plantar to the heel, there is a negative DKE value (gastroc equinus). If the fifth metatarsal head stops dorsal to the heel, there is a positive DKE value. The DKE value represents the heel height required to maintain subtalar neutral. I have found that examining for the DKE value is the single most important examination in my practice.
Understanding Hallux Dorsiflexion With The Ankle Fully Plantarflexed (HDP)
Dancers spend a lot of time landing, posturing, leaping and turning from the tiptoe position (demi-pointe). The dancer’s hallux must dorsiflex 90 degrees to accommodate her or his plantarflexed ankle, an amount significantly higher than the non-dancer norm of 60 to 65 degrees. If a dancer’s hallux cannot dorsiflex this much, he or she may be susceptible to plantar plate injury, medial first MPJ collateral sprains, dorsal impingement at the first MPJ or compensatory weight shifts to the hallux/functional hallux limitus or toward lateral ankle instability. Inadequate HDP is a major cause of morbidity in the dance population.
Technique. The patient maximally plantarflexes the ankle. The examiner assists the patient in holding this position. The patient then dorsiflexes the hallux to end range of motion. One would compare the line made by the plantar aspect of the first MPJ and the hallux plantar surface to the distal anterior margin of the leg while the ankle is maximally plantarflexed. The hallux-MPJ line must be 90 degrees or more acute to the previously described APF leg line.
For over 25 years, my general practice has enjoyed consistently favorable outcomes in the treatment of dance injuries. I hope the biomechanical concepts that I have learned in treating this specific patient population over the years can be beneficial in your practice as well.
Dr. Novella is an Adjunct Clinical Professor of Podiatric Orthopaedics at the New York College of Podiatric Medicine.
Dr. Caselli is a staff podiatrist at the VA Hudson Valley Health Care System in Montrose, N.Y. He is also an Adjunct Professor at the New York College of Podiatric Medicine and a Fellow of the American College of Sports Medicine.