SURGICAL TREATMENT OF PATELLAR INSTABILITY IN ADOLESCENT DANCERS

Background: Adolescent dancers may be a high-risk population for patellofemoral instability (PFI), but the condition remains under-investigated, to date, in this sub-group of athletes. Purpose: The purpose of this study was to (1) investigate the descriptive epidemiology of PFI in adolescent dancers, (2) analyze the efficacy of various patellar stabilization procedures within this population, and (3) compare PFI in dancers to a larger control group of matched, non-dancer athletes. Methods: A retrospective review of athletes, ages 10 to 19, who presented to a single tertiary care center with PFI between 2008 and 2017 was performed. Based on each patient’s primary sport, the cohort was divided into a dancer and a non-dancer control group. Demographics, clinical and radiologic features, surgical stabilization technique, and postoperative course and clinical outcomes were collected. Independent categorical groups were tested using chi squared and Fisher exact tests. Results: 258 adolescent athletes were included, 41 of whom were dancers, all females. This group was therefore matched with a control group of similarly aged, all-female athletes with PFI (Table 1). 54 athletes had bilateral PFI, yielding 285 knees for analysis. There was no difference between dancer and non-dancer athletes’ age, BMI, laterality, mechanism of injury, nor number of preoperative instability events. However, dancers had lower Dejour Classifications (p=0.044), smaller patella inclination angles (20.9±8.14 versus 25.0±9.84; p=0.004), and smaller Caton-Deschamps Indices (1.18±0.161 versus 1.25±0.189; p=0.041). Among dancers, there was no association between surgical stabilization technique and rates of recurrent instability (p=0.418) nor re-stabilization procedures (p=1.0) (Table 2). However, dancers who underwent tibial tubercle osteotomy (TTO) had higher rates of subsequent, non-stabilization procedures (66.7%), all for implant removal, compared to those undergoing isolated medial retinacular repairs (MRP) (3.8%) (p<0.001). There was no difference between the dancer and non-dancer athletes’ rates of recurrent instability (p=0.297), re-stabilization procedures (p=0.061), nor subsequent non-stabilization procedures (p=0.242). Conclusions: Female dancers with PFI have similar demographic and clinical features as other female athletes with PFI, but have lower rates or less severe trochlear dysplasia, lateral tilt and patella alta. Therefore, the ligamentous laxity inherent in dancers may be a more powerful risk factor for PFI than other non-modifiable risk factors. Notably, the TTO was a powerful stabilization procedure for this sub-population with low rates of recurrent instability episodes and no revision stabilization procedures performed. Rates of implant removal surgery following TTO may be substantial, though this may be technique or surgeon dependent. Tables/Figures: [Table: see text][Table: see text]

Ultrasound Observation of Hip Translational Motion in Adolescent Dancers

Hip microinstability, characterized by supraphysiologic movement of the femoroacetabular joint, has recently been recognized as a clinically relevant pathology. The potentially detrimental effects of its presence on joint health make identifying microinstability important; however, due to its multifaceted nature, screening for microinstability presents challenges. Musculoskeletal ultrasound offers an opportunity to visualize the arthrokinematics of the femoroacetabular joint on dynamic evaluation. Dancers may be particularly afflicted by microinstability due to the unique demands of their discipline. This study describes a method for evaluating femoral translation using dynamic ultrasound in adolescent dancers. One hundred forty-two dancers (117 females and 25 males) were recruited from a northeast high school dance program. Females mean age was 16.02 ± 1.06 years, mean BMI 20.35 ± 2.30 kg/m2, and mean years of dance experience 10.91 ± 2.84 years. Males mean age was 15.84 ± 1.26 years, mean BMI 21.78 ± 2.84 kg/m2, and mean years of dance experience 7.96 ± 2.82 years. Two hundred eighty-four hips were visualized under ultrasound imaging with the participants in both a neutral position and with the hip extended and externally rotated. The distance (mm) the femoral head was positioned anterior to the acetabulum was recorded for both these positions. The calculated difference in these values represented anterior translation. For female hips, the total mean anterior translation was 1.23 ± 2.01mm (-4.8 to 9.30 mm); for male hips, the mean of anterior translation was 1.39 ± 2.22 mm (-7.90 to 5.90 mm). This study identified a normative value range for hip anterior translational motion under dynamic ultrasound among a healthy population of adolescent dancers.

Predicting Injury Status in Adolescent Dancers Involved in Different Dance Styles: A Prospective Study

The positive effects of dance on health indices in youth are widely recognized, but participation in dance is accompanied with a certain risk of injury. This prospective study aimed to investigate injury occurrence and to evaluate the possible influences of specific predictors on the occurrence of musculoskeletal problems and injuries in adolescent dancers. Participants were 126 dancers (21 males; 11–18 years), who were competitors in the urban dance, rock and roll, and standard/Latin dance genres. Predictors included sociodemographic factors, anthropometric/body build indices, sport (dance) factors, and dynamic balance. The outcome variable was injury status, and this was evaluated by the Oslo Sports Trauma Research Centre Overuse Injury Questionnaire (OSTRC). Predictors were evaluated at baseline, and outcomes were continuously monitored during the study period of 3 months. During the study course, 53% of dancers reported the occurrence of a musculoskeletal problem/injury, and dancers suffered from an average of 0.72 injuries over the study period (95% CI: 0.28–1.41), giving a yearly injury rate of 280%. Gender and dance styles were not significantly related to the occurrence of injury. Higher risk for injury was evidenced in older and more experienced dancers. Dynamic balance, as measured by the Star Excursion Balance Test (SEBT), was a significant protective factor of injury occurrence, irrespective of age/experience in dance. Knowing the simplicity and applicability of the SEBT, continuous monitoring of dynamic balance in adolescent dancers is encouraged. In order to prevent the occurrence of musculoskeletal problems/injuries in youth dancers, we suggest the incorporation of specific interventions aimed at improving dynamic balance.

Internal Training Load Measures in Elite Adolescent Ballet Dancers

Training load has been identified as a risk factor for musculoskeletal injury in sport, but little is known about the effects of training load in dance. The purpose of this study was to describe adolescent dancers' internal training load (ITL) and compare objective and subjective measures of ITL using heart rate (HR) training impulse methods and session Rating of Perceived Exertion (sRPE), respectively. Fifteen female elite adolescent ballet dancers at a vocational dance school volunteered to participate in the study. Internal training load data using HR and sRPE were collected over 9 days of multiple technique classes at the midpoint of the dancers' training year. Heart rate data were quantified using Edwards' training impulse (ETRIMP) and Banister's training impulse (BTRIMP), and sRPE was estimated from the modified Borg 0 to 10 scale and class duration. Descriptive statistics (median [M], and interquartile range [IQR]) were determined in arbitrary units (AU), and were as follows for all classes combined: ETRIMP: M = 134 AU (IQR = 79 to 244 AU); BTRIMP: M = 67 AU (IQR = 38 to 109); sRPE: M = 407 AU (IQR = 287 to 836 AU). The association and agreement between objective and subjective ITL measures in ballet and pointe class was assessed using Spearman correlations (rs) and adjusted Bland-Altman 95% limits of agreement (LOA), respectively, with alpha set at 0.05. A significant moderate positive correlation was found between ETRIMP and BTRIMP in pointe class (rρ = 0.8000, p = 0.0031). The mean difference (LOA) between ETRIMP and BTRIMP was 121 AU (33 to 210 AU) in ballet and 43 AU (-3 to 88 AU) in pointe. It is concluded that some, but not all, measures of ITL in elite adolescent ballet dancers are comparable. Additional research is needed to examine the utilization of ITL measures for evaluating dance-related injury risk, as well as the application of ITL to inform the development of effective injury prevention strategies for this high-risk population.

The Relationship between Vitamin D Levels, Injury and Muscle Function in Adolescent Dancers

Vitamin D has been shown to benefit a diverse range of health functions including muscle function. The aim of the present study was to identify serum 25(OH)D3 levels in a sample of adolescent dancers and compare them to muscle function and injury incidence. We incorporated a cross-sectional design to study 49 pre-professional male and female dancers (17±4.44 yrs, 52.1±6.72 kg, 1.63±0.07 m) in full-time training in Bazil. Serum 25[OH]D3 was analyzed by Enzyme-linked Immunosorbent Assay; quadriceps and hamstring peak torque and muscle fatigue were measured by isokinetic dynamometer at 60 and 300° s−1. Injury type and location in the previous 6-months were determined by self-report questionnaire. Participants were categorized into 2 groups: normal or insufficient/deficient (>or<30 ng/ml 25[OH]D3). Results indicated the normal serum 25[OH]D3 group had significantly lower fatigue rates than the insufficient/deficient group (p<0.05) but not for the other muscle function parameters. Fifty-seven percent of participants reported at least 1 injury. The most common were sprains (33%) and tendinopathies (19%). Injured dancers had significantly lower peak torque at 60°/s. The link between serum 25[OH]D3 and reduced muscle fatigue resistance has not been shown before, though the underlying mechanisms aren’t apparent and the link between muscular strength and injury has been previously evidenced.

You’ve Got to Sell It!

This chapter explores the interplay between what is sold, bought, and invested in at dance competition events. Dance competitions, which focus on contemporary, jazz, tap, hip-hop, and ballet, and attract thousands of competitors, most of whom are adolescent girls, operate on a “pay to dance” system. Using a qualitative research approach and a theoretical framework rooted in literature on the construction of bodily ideals, the dancer’s contributions to contemporary dance practices, the formation of dancing communities, and dance learning in relation to ideas of conspicuous consumption and the experience economy, the chapter demonstrates that dance competitions offer adolescent dancers a meaningful venue through which to perform, build community, and nurture transferable proficiencies. Although not explicitly “for sale,” these qualities provide an understanding of why competitors “pay to dance.”