Faculty Bibliography

Despite its widespread and long term use, the effectiveness of iontophoresis to increase the delivery of dexamethasone sodium phosphate (DSP) remains controversial. The goal of this study was to quantitatively compare the DSP concentrations in dermis' dialysates in two delivery scenarios: with and without iontophoresis. Interstitial fluid concentrations were measured by cutaneous microdialysis. Passive and active iontophoresis were applied simultaneously on the skin of the forearm in eight healthy adult participants using each participant as his/her own control. The iontophoresis apparatus and procedures were identical to those used in common clinical practice. Iontophoresis electrodes were loaded with 2 mL of 4.4 mg/mL of preservative-free DSP solution. Electric current (4 mA) was applied for 20 min. Dialysate samples were collected for 2 h and analyzed for DSP and its active metabolite dexamethasone (DXM). Seven out of eight iontophoresis sites contained quantifiable levels of DSP and DXM, whereas none of the samples collected at the passive site contained either form of the drug. In conclusion, this study demonstrates that iontophoresis significantly (p < 0.0001) increases delivery of DSP to the dermis compared with passive delivery of the same, and that microdialysis can be used to monitor DSP delivery and DXM formation in skin. (c) 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:191-196, 2014.

Fatigue is often thought of as any transient exercise-induced reduction of work capacity. In fact, it is a complex phenomenon caused by overlapping and interacting peripheral and central mechanisms. There is a known relationship between fatigue, diminished performance, and injury. This paper reviews what is currently known about fatigue in the current literature.

BACKGROUND: Coxa saltans refers to a constellation of diagnoses that cause snapping of the hip and is a major cause of anterior hip pain in dancers. When the internal type is accompanied by weakness or pain, it is referred to as iliopsoas syndrome. Iliopsoas syndrome is the result of repetitive active hip flexion in abduction and can be confused with other hip pathology, most commonly of labral etiology. PURPOSE: To report the incidence, clinical findings, treatment protocol, and results of treatment for iliopsoas syndrome in a population of dancers. STUDY DESIGN: Retrospective case series; Level of evidence, 4. METHODS: A retrospective database review of 653 consecutive patients evaluated for musculoskeletal complaints over a 3-year period was completed. The diagnosis of iliopsoas syndrome was made based on anterior hip or groin pain, weakness with resisted hip flexion in abduction, or symptomatic clicking or snapping with a positive iliopsoas test. Patients identified with iliopsoas syndrome were further stratified according to age at time of onset, insidious versus acute onset, duration of symptoms, side of injury, presence of rest pain, pain with activities of daily living, and associated lower back pain. All patients diagnosed with iliopsoas syndrome underwent physical therapy, including hip flexor stretching and strengthening, pelvic mobilization, and modification of dance technique or exposure as required. RESULTS: A total of 49 dancers were diagnosed and treated for iliopsoas syndrome. Within this injured population of 653 patients, the incidence in female dancers was 9.2%, significantly higher than that in male dancers (3.2%). The mean age at the time of injury was 24.6 years. The incidence of iliopsoas syndrome in dancers younger than 18 years was 12.8%, compared with 7% in dancers older than 18 years. Student dancers had the highest incidence (14%), followed by amateur dancers (7.5%), while professional dancers had the lowest incidence (4.6%). All patients responded to conservative treatment, and no patients required corticosteroid injections or surgical intervention. CONCLUSION: This is the largest series reported to date of iliopsoas syndrome in the dance population, treated noninvasively. This study supports that conservative treatment with nonsteroidal anti-inflammatory medication, activity modification, and a physical therapy regimen specific to the iliopsoas should be the primary treatment for patients with iliopsoas syndrome. CLINICAL RELEVANCE: This study supports current literature and conservative treatment of iliopsoas syndrome diagnosis. Furthermore, this study gives specific information regarding incidence of iliopsoas syndrome in dance populations and provides a test for diagnosis and an algorithm for treatment.

Micro-finite element analysis applied to high-resolution (0.234-mm length scale) MRI reveals greater whole and cancellous bone stiffness, but not greater cortical bone stiffness, in the distal femur of female dancers compared to controls. Greater whole bone stiffness appears to be mediated by cancellous, rather than cortical bone adaptation. INTRODUCTION: The purpose of this study was to compare bone mechanical competence (stiffness) in the distal femur of female dancers compared to healthy, relatively inactive female controls. METHODS: This study had institutional review board approval. We recruited nine female modern dancers (25.7 +/- 5.8 years, 1.63 +/- 0.06 m, 57.1 +/- 4.6 kg) and ten relatively inactive, healthy female controls matched for age, height, and weight (32.1 +/- 4.8 years, 1.6 +/- 0.04 m, 55.8 +/- 5.9 kg). We scanned the distal femur using a 7-T MRI scanner and a three-dimensional fast low-angle shot sequence (TR/TE = 31 ms/5.1 ms, 0.234 mm x 0.234 mm x 1 mm, 80 slices). We applied micro-finite element analysis to 10-mm-thick volumes of interest at the distal femoral diaphysis, metaphysis, and epiphysis to compute stiffness and cross-sectional area of whole, cortical, and cancellous bone, as well as cortical thickness. We applied two-tailed t-tests and ANCOVA to compare groups. RESULTS: Dancers demonstrated greater whole and cancellous bone stiffness and cross-sectional area at all locations (p < 0.05). Cortical bone stiffness, cross-sectional area, and thickness did not differ between groups (>0.08). At all locations, the percent of intact whole bone stiffness for cortical bone alone was lower in dancers (p < 0.05). Adjustment for cancellous bone cross-sectional area eliminated significant differences in whole bone stiffness between groups (p > 0.07), but adjustment for cortical bone cross-sectional area did not (p < 0.03). CONCLUSIONS: Modern dancers have greater whole and cancellous bone stiffness in the distal femur compared to controls. Elevated whole bone stiffness in dancers may be mediated via cancellous, rather than cortical bone adaptation.

This technical report of the Standard Measures Consensus Initiative of the International Association for Dance Medicine and Science (IADMS) describes the results of the committee's multi-year effort to synthesize information regarding the tests and measures used in dance-related research, protocols for reporting injuries, and appropriate use of available technologies to aid in standardizing such matters. Specific recommendations are presented, with accompanying rationales, to facilitate consensus among members of the dance medicine and science community. An Executive Summary of this Technical Report, which contains implementation strategies and appendices, should soon be available on the IADMS website.

Retrospective studies have suggested that dancers performing on inclined ("raked") stages have increased injury risk. One study suggests that biomechanical differences exist between flat and inclined surfaces during bilateral landings; however, no studies have examined whether such differences exist during unilateral landings. In addition, little is known regarding potential gender differences in landing mechanics of dancers. Professional dancers (N = 41; 14 male, 27 female) performed unilateral drop jumps from a 30 cm platform onto flat and inclined surfaces while extremity joint angles and moments were identified and analyzed. There were significant joint angle and moment effects due to the inclined flooring. Women had significantly decreased peak ankle dorsiflexion and hip adduction moment compared with men. Findings of the current study suggest that unilateral landings on inclined stages create measurable changes in lower extremity biomechanical variables. These findings provide a preliminary biomechanical rationale for differences in injury rates found in observational studies of raked stages.

Modern (or contemporary) dance has become increasingly popular, yet little has been reported with respect to modern dance injuries and their consequences. The purpose of this study is to define the incidence, risk factors, and management of musculoskeletal injuries in professional modern dancers. A total of 184 dancers in the United States completed an anonymous 17-page questionnaire on their injuries, including extensive details regarding the two most severe injuries that had occurred in the prior 12 months. According to their self-reports, a total of 82% of the dancers had suffered between one and seven injuries. The foot and ankle (40%) was the most common site of injury, followed by the lower back (17%) and the knee (16%). The rate of injuries was 0.59 per 1,000 hours of class and rehearsal. Injured male dancers returned to full dancing after a median of 21 days, while females returned after a median of 18 days. Most dancers missed no performances due to injury. Of the medical consultations sought by dancers for their injuries, 47% were made to physicians, 41% to physical therapists, and 34% to chiropractors. The majority of dancers adhered to the advice given them by consultants (87% of males and 78% of females for the most severe injury). While the majority of injuries were considered work-related (61% of the most severe injury and 69% of the second most severe), few were covered by Workers' Compensation insurance (12% and 5% respectively). These professional modern dancers suffer from a rate of injury similar to other groups of professional dancers. Most dancers return to a partial level of dancing several weeks before attempting full-capacity dancing.

OBJECTIVE: To determine the effect of gender and inclined floor on time to stability (TTS) after landing from a vertical jump. DESIGN: This study used a repeated measures design with male and female professional dancers landing on a flat and 4 inclined floors. A repeated measures univariate analysis of variance (gender x floor) was performed on TTS in the anterior-posterior and medial-lateral directions. SETTING: Biomechanics laboratory. PARTICIPANTS: Twenty-three female and 13 male professional dancers. INDEPENDENT VARIABLES: Gender and floor inclination (flat, posterior, anterior, lateral, and medial). MAIN OUTCOME MEASURES: Time to stability in the anterior-posterior and medial-lateral directions after landing from a vertical jump. RESULTS: Female dancers exhibited longer TTS in both directions (P 0.3). CONCLUSIONS: Female dancers exhibited longer TTS after landing from a vertical jump compared with their male counterparts. This balance difference may be a factor related to the higher rate of ankle sprain among female dancers. Additionally, professional dancers exhibited similar TTS when landing on flat and inclined floors.