Dance Medicine

Lyle J. Micheli, MD • Peter G. Gerbino II, MD • Ruth Solomon • John Solomon, PhD

Division of Sports Medicine • The Children's Hospital

          The dancer, like the athlete, experiences substantial physical demands related to movement and impact. The injuries sustained in dance - as well as the measures taken to treat, rehabilitate, and prevent these injuries - are similar to those encountered in sports. Sports medicine personnel are sympathetic to the need for continued activity, dynamic treatment and rehabilitation, and the use of so-called relative rest in handling injuries. Just as an improved understanding of the stresses placed upon the body in athletic activity has improved training techniques, enhanced performance, and decreased the incidence of injuries, the scientific study of dance is expected to yield similar benefits.

          The Division of Sports Medicine at Children's Hospital, in addition to providing treatment and follow-up care to children and adolescents with orthopaedic sports injuries, has an active interest in dance medicine. Dr. Micheli has been the attending physician for the Boston Ballet since 1977. Dr. Peter Gerbino is former Director of Performing Arts Medicine in the Department of Orthopaedic Surgery at the University of Cincinnati. Visiting Advisor on Dance, Ruth Solomon, is Professor Emeritus in Theater Arts/Dance at the University of California, Santa Cruz.

          In 1984, with the publication of the article ÒPhysiologic Profiles of Female Ballerinas,Ó 1 the Division of Sports Medicine at Children's Hospital began a tradition of research in the field of dance medicine. The Division personnel's collective experience in treating elite ballet dancers has been analyzed here to improve our understanding of musculoskeletal injuries in dancers.

What Makes Dancers Unique?

          In sports medicine it has proved useful to delineate risk factors for injury. These may relate to anatomic alignment, muscle-tendon imbalance, technique, equipment, playing surface, and alteration in the intensity or duration of training. As a first step towards characterizing such risk factors in dancers, we studied the physical characteristics of dancers as compared to average women.

          Nine elite ballerinas from the Boston Ballet were compared with two sets of age-matched controls: 25 female advanced ballet students, and 25 female non-dancers. Utilizing the facilities and staff at Northeastern University and the services of a physical therapist from the Boston Ballet, a physiological profile was developed for each subject through testing in the following areas: cardiovascular fitness, muscle strength, anthropometry and body composition, and flexibility. Aerobic fitness was greater in the dancers than in the non-dancers, but was lower than that previously observed in endurance athletes such as runners.2 An important muscle imbalance of ankle plantar flexors to dorsiflexors at a ratio of 6.2 to 1 was consistently identified in the dancers. The nine ballerinas were found to constitute a highly homogeneous group in terms of height, weight, age, and body composition, which, it was speculated, might reflect both artistic and physiologic selection at the elite level. As was no doubt to be expected, these dancers showed a remarkable degree of flexibility, and when the younger dancers were compared to the control subjects they were found to have significantly increased external rotation and abduction at the hip.

Specific Issues in Dancers

En Pointe
          The age at which en pointe training should be introduced is disputed. En pointe technique may be associated with an increased risk of injury in skeletally immature patients, particularly those with insufficient physical conditioning. (Figure 1) Based on observation of the anatomic demands of the en pointe technique we tested two factors in an attempt to develop an objective basis for determining readiness for en pointe training: 1) Range of motion in plantar flexion and dorsiflexion at the ankle, and 2) Strength of the muscles that flex and extend the ankle and knee.3 Three groups of subjects were recruited: Group I were dancers who averaged just over one year of en pointe work; Group II were dancers who had not yet begun en pointe training; Group III were gender- and age-matched non-dancer controls. A registered physical therapist measured range of motion using a goniometer, and peak torque at the knee and ankle using a Cybex machine.

           The principle findings were as follows: 1) Ankle motion was greater in dancers than in non-dancers, 2) Non-dancers had slightly greater strength than dancers, and 3) Ballet students with one year of en pointe training tended to be marginally stronger than dancers without such training. The findings suggest that strength might be an important consideration when determining readiness for en pointe training, but the data did not produce a predictable transition point. The greater strength of non-dancer controls was notable.

          A number of methods have been used to gather the footprints needed to measure FPA. We chose one that was used in two previous studies conducted by researchers at the Converse Biomechanics Laboratory, whose facilities and staff were made available for our study. Use of their technique allowed us to compare our findings in dancers with previous findings in three large groups of non-dancer controls.

           The average FPA among dance students aged seven to ninteen years was 16 degrees of outward rotation. This is more than double the value measured in studies of non-dancer controls (4.6 degrees to 7.0 degrees). FPA increased with years of training from an average of 11 degrees in students with one to three years experience up to an average of 24 degrees at seven years of training; however, the average FPA declined to approximately 16 degrees in the students who had trained for eight years or more. We concluded that ballet training does produce increased external rotation in the gait of student dancers, with some correction after age 11.

           Currently we are comparing the FPA in dancers with that in figure skaters. Since skating requires that the feet be maintained in a position of neutral rotation, we anticipate that the FPA of skaters and dancers will differ significantly. Preliminary findings suggest that this is indeed the case.

Dancer's Hip
           So-called dancer's hip is a painful snap occurring on the medial and anteromedial aspects of the hip when the leg is descending from a position of full abduction and external rotation (a common maneuver in dance). Only in the last few years has the cause of this condition been substantiated as a relative impingement of the iliopsoas tendon across the neck of the femur, which results in a painful tendinitis of the iliopsoas. We have explored treating this injury with fluoroscopically guided corticosteroid injection of the iliopsoas tendon sheath, and the results have been promising: in 17 female athletes with a mean age of nearly 18 years, nine of whom were dancers, relief was excellent in ten, good in three, fair in two, and poor in 2 cases.5 These results are comparable to those achieved with surgical release of the tendon.6-8

          In its early stages medial snapping of the hip is usually painless and seemingly benign; however, we advocate intervention before the condition develops into full-blown tendinitis necessitating the type of long hiatus in training and performance that dancers dread. Progression to tendinitis can be avoided by identifying and correcting errors in technique and problems with alignment, and by performing exercises to increase flexibility of the iliopsoas and hip external rotators while strengthening the external rotators, adductors, and internal rotators. In cases where tendinitis has been treated with injection this same regimen should be implemented as soon as possible to prevent recurrence of the condition.

Back Complaints in Dancers
          Back injuries are quite common in dancers.9-12 Low back pain can be seen at almost any age or stage of dance development, and is often associated with increased lumbar lordosis, particularly during movement or jumping. (Figure 1) There appears to be an increased incidence of spondylolysis in dancers. We emphasize the need for early detection of spondylolysis and prompt treatment to allow potential healing of the pars defect and to limit the risk of progression to spondylolisthesis. (Figure 2A) The goal of treatment is to return the dancer or athlete to full painless activity as soon as possible. We rely heavily on the use of the antilordotic version of the Boston brace (Figure 2B) (in which the dancer may resume limited activities if no pain is present), and strict adherence to a systematic and balanced program of stretching and strengthening exercises. For stretching, the proprioceptive neuromuscular facilitation technique is recommended, focusing especially on the hamstrings and lumbodorsal fascia(13). In addition, stretching of the anterior hip should be emphasized, as hip flexion contractures are often seen in combination with hyperlordosis of the low back. A program of abdominal and pelvic strengthening exercises must be included in any rehabilitation regimen. We have found swimming to be a well-tolerated and very useful activity. As in the rehabilitation of any athletic injury, the level of activity should progress very slowly, without causing pain.

Other Conditions in Dancers

          Some additional conditions to which dancers are especially vulnerable include stress fractures of Lisfranc's joint,14 os trigonum impingement,15 and flexor hallucis longus tendonitis.16

Injury Patterns in Dancers

          For the past five years the Boston Ballet has collected data on injuries to its dancers in an attempt to explore new approaches to meeting the health needs of dancers while cutting associated costs. Analysis of the data has improved our understanding of the epidemiological and financial aspects of dance injuries in a professional company.17-19

Epidemiology
          Over the five year period the percentage of dancers in the company that were injured in a given year, and the total number of injuries, have declined and stabilized at what are now believed to be fairly constant levels. The rate of injury appears to be similar across age, rank, and gender. Generally, the rate of reported injury is greatest in the opening months of the season (September and October), recedes steadily into January, peaks again in February and March, and declines as the season winds down to closing in May. We conclude from this that the dancers are at greatest risk for injury when they resume a heavy work schedule after a period of relative inactivity.

          Over two-thirds of the injuries involve the lower extremities. Nearly one-fifth involve the spine. Foot injuries are more common in female dancers; ankle and spine injuries are evenly distributed between genders. Nearly half of the injuries each year represent a strain, sprain or tendinitis. These can be diagnosed, treated, and rehabilitated cost effectively by utilizing the company's physician and contracted health care providers.

Financial
          Under a worker's compensation provider, the insurance costs for 60 Boston Ballet dancers climbed to $792,000 by the 1993-94 season. In an attempt to cut costs the Ballet began contracting directly with selected health care providers the following season, and has paid on average approximately $550,000 a year for health care costs since then. Assuming a constant premium under the old system, the Ballet believes that it has saved well over a million dollars over the last five years by switching to the new system.

          There has also been a noticeable improvement in company morale during the years studied due in part, we believe, to increased awareness among the dancers that the company is making a concerted effort to prevent injuries and to limit the impact of injuries when they do occur by providing reliable medical assistance. The availability of a company physician, and through him of selected health care providers who are known and trusted, is a major factor. Other elements - including pre-and post-season screenings, transition classes, and an Injury Prevention Focus Group - also contribute to the success of the new program.

Conclusions

          Doing research with dance and dancers has been an enriching experience for the staff of the Sports Medicine Division. It has drawn us into valuable collaborations with the surrounding community, and enlarged our perspectives without noticeably diminishing our resources. If there is resistance elsewhere in the medical, athletic, or dance communities to acknowledging the dancer-as-athlete linkage there has not been any evidence of it at the Division. We look forward to continuing this aspect of our work.

Lyle J. Micheli, MD is Director of the Division of Sports Medicine at The Children's Hospital and Associate Clinical Professor of Orthopaedic Surgery at Harvard Medical School

Peter G. Gerbino II, MD is an Attending Surgeon at The Children's Hospital and Instructor in Orthopaedic Surgery, Harvard Medical School

Ruth Solomon is Coordinator of Dance Medicine Research in The Division of Sports Medicine at The Children's Hospital and Professor Emeritus of Theater Arts/Dance at the University of California, Santa Cruz

John Solomon, PhD is Editorial Advisor of The Children's Hospital Sports Medicine Foundation

Address correspondence to:
Mark Jenkins; Editorial Associate; Division of Sports Medicine; Children's Hospital, 300 Longwood Avenue; Boston, MA 02115; e-mail: mjenkins@vineyard.net