December 16, 2014
With the holiday season come a host of traditions. There are tree trimming and the lighting of the menorah; there are caroling and jingle bell runs. And there’s that new favorite: wearing tacky sweaters.
There is, as well, the Nutcracker.
My family and I will be watching this weekend at Columbus’ BalletMet production. This will mark our fifth year in attendance, and I’ve been impressed with the dancers’ artistry and skill each time I’ve seen the show.
Truth be told, I never went to any ballet until I was an adult. My affection for the Nutcracker derives not from my own childhood Christmas memories, but from the work I did as a sports medicine fellow, where I ‘covered’ the Boston Ballet for a year. What a great experience that was!
‘Dance Medicine,’ as many of you know, is a special niche of sports medicine. Like any sport, dance has its own language, it’s own mental and physical challenges, its own equipment, and its own injury patterns. I have not managed too many cases of hallux rigidus, FHL tendonitis or posterolateral ankle impingement outside of the dance world.
I grew very fond of this field during my training, and I continue to seek out opportunities to participate in this world. And so I took extra pleasure in our September 2014 editions, which offered two new pieces of original research in dance medicine: Body Mass Index, Nutritional Knowledge, and Eating Behaviors in Elite Student and Professional Ballet Dancers and a brief report, Early Signs of Osteoarthritis in Professional Ballet Dancers: A Preliminary Study. I commend both of them to you.
With the special performance and contemporary aesthetic demands of ballet comes a pressure to have a relatively low body mass index (BMI). This is a trend, most especially for female dancers, that has been noted by many: the prima ballerina of the early 20th century had a very different body habitus than the ballerina of a 2014 New York City or London company. Some have attributed this to the influence of Georges Ballanchine, the founder of the New York City ballet. The ‘Ballanchine Body’ has been described by his protegé, Suzanna Farrell, as “leggy, linear, musical, unsentimental and, of course, untouchably beautiful.” Others have called it “kind of scary.”
The CJSM study on BMI looked at both pre-professional students and professional dancers. The authors measured BMI and looked at two additional outcome measures: an assessment of nutritional knowledge [the General Nutrition Knowledge Questionnaire (GNKQ)], and of eating behaviors [the Eating Attitude Test—26 (EAT-26)].
An unsurprising finding, I think: the mean BMI of professional female dancers was low, 18.9 kg/m2. A very interesting finding was the concerning change in EAT-26 scores for pre-professional female students in their fourth year of training, the approximate age when many young female dancers are beginning to start puberty (14+/-0.47). The authors note that “this is later than the normal population because of the increased workload and lower BMI of this population.” The authors comment further on this finding: “This sudden rise in higher nutritional concern for females could be prompted by the bodily changes that occur during puberty and body composition altering to accumulate, approximately, a further 5% of body fat.This may be misinterpreted as “putting on weight” instead of natural development, hence an overconcern with food and dietary intake.”
The study on early signs of osteoarthritis (OA) in ballet dancers is one of our “Brief Reports.” For aspiring authors out there, the “Brief Report” format is described in our ‘Instructions for Authors’ as a flexible format for “….clinical studies that are preliminary or limited in scope but with important findings to report.” There is a 200 word limit for the structured abstract, a 1000 word limit for the manuscript, and a limit of 10 references.
Several retrospective case control studies have raised the concern for increased risk of OA in retired dancers, most especially in the hip, knee and first metatarsophalangeal (1st MTP) joints. What is special about this new CJSM cohort study is this that the authors were looking for early signs of radiographic (plain film and MRI) evidence of OA in active dancers. The authors do indeed report finding early signs of OA in the hip, knee and 1st MTP joints. Given the limitations of the small study size, they go on to note that future prospective studies should control for medical history (e.g. history of joint macrotrauma, osteopenia) and other confounding variables. I wonder, too, if future studies may take advantage of some of the intriguing new imaging modalities [(e.g. delayed gadolinium enhanced MRI of cartilage (dGEMERIC)] that are much more sensitive than plain film or MRI for detecting early, sub-clinical evidence of degenerative joint disease.