Self-Reported Hip Problems in Professional Ballet Dancers: The Impact on Quality of Life.
Because published injury rates are derived largely from self-reported surveys or interviews, the way an "injury" is defined can influence how the question is answered by the dancer. (2) The definition of an injury has been variously defined in prior studies as musculoskeletal problems that: 1. affect the subject's dancing in any way, (1) 2. result in dance participation being restricted for at least 24 hours, (4,6) 3. cause absence from performance or rehearsal, and 4. require medical assistance. (7) This variation makes it challenging to compare injury rates across studies and may outright change the answer a dancer provides.
The Hip Disability and Osteoarthritis Outcome Score (HOOS) questionnaire is a self-administered instrument that addresses symptoms and functional impairment due to a hip problem. (8) There are five separate sub-scores addressing: hip pain, other hip symptoms, function in activities of daily living (ADLs), function in sports and recreation, and hip-related quality of life. The instrument is validated to assess hip disability in older subjects with or without osteoarthritis (8) and medical patients who have undergone total hip arthroplasty. (9) The HOOS has not been validated in a younger population or in athletes. In addition to the HOOS, there are other instruments that address hip function, such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Oxford Hip Score. These instruments are used to assess the impact of osteoarthritis and potential need for joint replacement and are not directly applicable to athletic populations. To the authors' knowledge, there are no self-reported survey instruments that are validated to detect hip disability due to injury in high-level dancers or athletes.
The aim of this study was to ascertain the relationship between dancers' history of hip injuries or hip problems and HOOS sub-scores. We hypothesized that dancers who reported a history of hip problems would demonstrate lower (i.e., more debilitating) HOOS pain and sports sub-scores.
Dancers from a large urban professional ballet company participated in the 30-minute Annual Post-Hire Health Screen for Professional Dancers developed by the Dance/USA Task Force on Dancer Health. The screen consists of a general demographic and medical history questionnaire followed by physical assessment. The physical assessment included an abbreviated evaluation of vital signs and a cardiovascular fitness test, along with balance, lower extremity strength and flexibility, overall joint hypermobility, and functional movement and control testing. Standard guidelines for administration of the screen were utilized to ensure uniform testing. The screen was performed at the beginning of the company's 2014-2015 performance season. All participants signed a consent form approved by these authors' Institutional Review Board before data collection, and participants were informed of the study protocols before consenting.
The dancers completed the screening questionnaire, which included questions about dance exposure history, medical history, injury history, and an additional instrument introduced by these authors that included questions regarding hip-specific medical history, hip symptoms, and the HOOS Hip Survey. Dance injury history was elicited as follows: "Have you ever had an injury, like a sprain, strain, or any other injury that caused you to miss more than 2 days of rehearsal or performances? Please indicate the body part" and "Do you have any current or previous history of hip problems during your adulthood?" The HOOS addressed level of self-reported hip disability and contained five subscales: hip pain ("pain"), other hip symptoms ("symptoms"), function in activities of daily living ("ADLs"), function in sports and recreation ("sports"), and hip-related quality of life ("QoL"). Each subscale was scored on a five-point Likert scale to transform the raw HOOS survey answers into scores from 0 to 100, where a lower score indicates greater disability, as previously described in the literature. (10) Additional survey questions addressed the presence or absence of hip pain when performing nine different ballet movements, answered with a simple "yes" or "no." These movements are listed in Table 1. They consist of positions and movements that require extreme range of motion in hip abduction, flexion, and extension. All of the movements also require hip external rotation.
Questionnaire and screening data were collected and managed using Research Electronic Data Capture (REDCap), an electronic data capture tool hosted at Northwestern University. Data were exported to Microsoft Excel for analysis. Unpaired Student's t-test was used to evaluate differences in HOOS sub-scales between dancers who reported a hip problem versus those without such history, and Fisher's exact test was applied to compare responses between the former and latter. A Bonferroni correction was applied to account for multiple comparisons, with p < 0.010 meeting statistical significance. Separately, the dancers' survey answers were evaluated for the presence of hip pain with the ballet movements listed in Table 1.
Demographic data for the study's participants are presented in Table 2. Forty dancers (20 women, 20 men) participated in the annual screening, and 37 (18 women, 19 men) fully completed the questionnaire and were included in the analysis. The mean age of the participants was 25.7 years (range: 18 to 33 years), with an average of 8 years (range: 1 to 16 years) of professional ballet experience. Two of the 37 dancers reported a history of hip injury that caused them to miss more than 2 days of rehearsal or performance. Eight of the 37 dancers (including the two with a hip injury) reported a history of hip problems during adulthood. Given the low number of dancers with a hip injury and greater number who reported having had a hip problem, all of the following analyses compare the dancers who were positive for hip problems versus those who were not.
The dancers with a hip problem history reported significantly lower sub-scores for pain (p = 0.006) and QoL (p = 0.0001). The remaining sub-scores trended toward, but did not meet, statistical significance: symptoms (p = 0.047), ADLs (p = 0.047), and sports (p = 0.016). These data are depicted in Figure 1.
Six of the eight dancers (75%) with a history of hip problem reported hip pain with two or more of the ballet movements listed in the questionnaire (see Table 1). Seven of the 29 dancers (24%) without a hip problem also reported hip pain with two or more of the ballet movements. Fisher's exact test demonstrated that dancers with a history of hip problem were statistically more likely to report pain with two or more of the movements (p = 0.013), (Fig. 2). The most commonly reported painful ballet movements were ronde de jambe en l'air at 90[degrees] and holding developpe a la seconde.
Dancers who reported a history of hip problems demonstrated statistically significant low scores on the pain and QoL HOOS sub-scores. The remaining sub-scores, symptoms, ADLs, and sports, trended toward but did not meet significance. In addition to statistical difference, it is important to address the minimal detectable change for a given instrument; that is, how different scores must be on an instrument in order to be clinically meaningful. Previously reported minimal detectable changes (MDCs) in HOOS sub-scores have been tested in patients with osteoarthritis awaiting total hip arthroplasty. The MDCs were found to be 21.6 points (pain), 22.7 (symptoms), 17.7 (ADLs), and 24.4 (QoL). There was no reported MDC for the sports sub-score. (11) In the current study, the average differences on each of the five subscales were as follows: 11.5 (pain), 14.6 (symptoms), 8.1 (ADLs), 10.9 (sports), and 36.9 (QoL). Based on these data, the only clinically significant difference in this study was the QoL subscale (Table 3).
The HOOS is validated only to detect disability in older subjects with hip osteoarthritis and may, therefore, not detect hip symptoms and functional impairments in high-level dancers or athletes. The instrument also does not explicitly address dance-specific movements. Symptoms with dance-specific movements might be severe and functionally limiting but not be evident on the HOOS. The fact that the QoL sub-score was significantly lower for those dancers with a history of hip problems indicates that the presence of a hip problem should be viewed as a risk factor for diminished quality of life in this population.
In this study, dancers were asked about the presence of hip pain with ballet movements that require both static and dynamic extreme range of motion, including flexion, abduction, and extension. The dancers with reported hip problems were more likely to report pain with two or more of these movements. These results are preliminary and the clinical relevance is not known as the instrument used has not been validated and an appropriate scoring method is not known at this time. However, it appears likely that the presence of pain with a movement that is required in a dancer's daily life and work would have an impact on his or her quality of life, quality of work performance, and ultimately the ability to continue dancing professionally. Currently, there are no validated instruments that assess the extent of hip-related disability in professional dancers or high-level athletes. An activity-specific instrument such as HOOS may improve the ability to detect declining performance or quality of life in these high performance athletes.
Only two of the dancers reported a current hip injury; however, a total of eight acknowledged having had a hip problem. Thirteen additional dancers reported hip pain with certain ballet movements, but denied a history of hip problems. This difference highlights the importance of how "injury" is defined in a study. Posing a very specific question may lead to very specific results, but a broader question can be more sensitive in picking up dancers who have hip symptoms. In this study, the more open-ended questions yielded a greater number of positive responses. On the other hand, since the eight dancers who reported a hip problem described it largely in free text but did not indicate whether it was resolved or current, it is not known if any of the reported problems were ongoing.
There are several limitations to this study. The data were collected in a retrospective manner by self-report. This is a cross-sectional study, therefore history of a hip injury cannot be inferred to directly cause reduced quality of life. This is especially relevant since the reported problems could be either current or in the past. A relatively low number of dancers reported hip injuries or hip problems, which limits the interpretation of the data. The low number of reported injuries may be related to recall bias, completing the questionnaire in a rushed manner, or volitionally omitting a history of injury. Our specific definition of a "hip problem" as opposed to a "hip injury" limits the ability to compare these data to other studies.
The presence of hip problems and injuries should be viewed as a risk factor for lower quality of life in professional ballet dancers. Those with a history of hip problems and injuries are more likely to have hip pain with dance movements. This correlation persists despite lack of a significant effect of hip problems on the ability to perform ADLs. Further research is needed to explore the ability of a dancer-specific instrument, such as the HOOS, to address quality of life issues after hip problems in dancers.
We thank the Dance/USA Task Force on Dancer Health for the development of the Annual Post-Hire Health Screen for Professional Dancers. We also thank the Department of Orthopedic Surgery at Washington University in St. Louis for contributing the hip-specific questionnaire. Special thanks to the dancers and the ballet company administration for their participation and support.
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Claire Gross, MD, Monica Rho, MD, Daniel Aguilar, BS, and Maria Reese, MD, Rehabilitation Institute of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
Correspondence: Claire Gross, MD, 3231 South Euclid Avenue, Suite 500, Berwyn, Illinois 60402, USA; email@example.com.
Caption: Figure 1 Mean ([+ or -] SEM) HOOS subscores for Pain, Symptoms, ADLs, Sports, and QoL in dancers with and without a hip problem history (*statistically significant).
Caption: Figure 2 Hip pain during zero to one dance movements versus two or more dance movements in dancers with and without history of hip problem (p = 0.013).
Table 1 Survey Questions Regarding Pain with Ballet Movements Do you have pain while performing any of the following techniques? Left Right Ronde de jambe en l'aire at 90[degrees]? Yes No Yes No Plie in fourth position comfortably? Yes No Yes No Plie in fifth position comfortably? Yes No Yes No Holding a passe and retire? Yes No Yes No Holding a developpe a la seconde? Yes No Yes No Grande battement devant? Yes No Yes No Grande battement a la seconde? Yes No Yes No Grande battement arabesque? Yes No Yes No Single leg leaps such as a grand jete? Yes No Yes No Table 2 Baseline Characteristics of Study Participants History of No Hip Problem History Number 8 29 Sex (% female) 88% 38% Age (years) (*) 25.7 25.8 Training Exposure Professional experience (years) (*) 8 7.8 Training per day (hours) (*) 7.1 6.6 Training per week (hours) (*) 36.1 32.8 Injury History History of any lower extremity injury (% yes) 62% 76% Hip 25% 0% Thigh 0% 0% Knee 25% 17% Calf or Shin 0% 0% Ankle 12% 48% Foot or Toes 38% 21% Hip-Related Medical History History born breech (% yes) 0% 3% History hip problems during childhood (% yes) 12% 0% History of hip braces during childhood (% yes) 0% 0% (*) Mean. Table 3 HOOS Sub-Score Difference Versus the Minimal Detectable Change (MDC) for Patients with Osteoarthritis HOOS Sub-score Average Score Difference MDC (11) Pain 11.5 21.6 Symptoms 14.6 22.7 ADLs 8.1 17.7 QoL 36.9 (*) 24.4 (*) Meets MDC criterion.
Please Note: Illustration(s) are not available due to copyright restrictions.
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|Author:||Gross, Claire; Rho, Monica; Aguilar, Daniel; Reese, Maria|
|Publication:||Journal of Dance Medicine & Science|
|Date:||Jul 1, 2018|
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