Prevention of hip and knee injuries in ballet dancers

Is there an association between joint range of motion and muscle strength in young female dancers? And, does it depend on the effects of age and menarche?

Aiming to determine the association between joint range of motion (ROM) and muscle strength; and, the effect of age and menarche on those two factors; 132 pre-and post-menarche dancers, aged 12-14 years were assessed for joint ROM and for muscle strength at the hip, knee and ankle and foot joints. En-pointe ROM was significantly correlated with ankle plantar-flexors' (r = -.184) and with ankle dorsiflexors' muscle strength (r = -.221). Hip external rotation ROM was significantly correlated with knee extensors' strength (r = -.263). Pre-menarche dancers had higher joint ROM compared with post-menarche dancers; yet, dancers at post-menarche were stronger compared to dancers at pre-menarche. The slope coefficient was negative at the age of 12 in hip external rotation and in en-pointe (-0.80 and -0.52, respectively) and became steeper with age (age 13: -3.52 and -3.28, respectively; age 14: -6.31 and -4.42, respectively). Along maturation, dancers with high joints ROM showed reduced muscle strength. Pre-menarche dancers have higher joint ROM, yet reduced muscle strength, compared with post-menarche dancers. As the association between joint ROM and muscle strength might be involved with growth and development, young dancers should be screened along pubertal stages in order to decide the correct curricula and to prevent future injuries.

Association of Proximal and Distal Factors With Lower Limb Kinematics During a Classical Ballet Jump

CONTEXT

Excessive dynamic lower limb misalignment may predispose ballet dancers to jump-related injuries. However, it is unknown whether proximal and distal factors influence this movement pattern. The aim of this study was to investigate whether hip abduction strength, foot alignment, and ankle dorsiflexion range of motion (ROM) are associated with peak angles of hip adduction and internal rotation and knee abduction during the preparation and landing phases of a classical ballet jump.

DESIGN

Cross-sectional study.

METHODS

Forty-one healthy amateur ballet dancers were included. Hip abduction strength was evaluated isometrically using a handheld dynamometer, foot alignment was determined by the shank-forefoot alignment, and weight-bearing ankle dorsiflexion ROM was measured by performing the lunge test. Peak hip and knee angles were analyzed 3-dimensionally during the preparation and landing phases of a single-leg jump. A Pearson correlation matrix was used to investigate the association of hip abduction strength, shank-forefoot alignment, and ankle dorsiflexion ROM with peak angles of hip adduction and internal rotation and knee abduction during the preparation and landing phases of the jump.

RESULTS

Greater hip abduction strength was associated with greater peak hip internal rotation angle (r = .43, P < .05), but not with peak hip adduction and knee abduction angles during the preparation phase of the jump. There were no associations of shank-forefoot alignment and ankle dorsiflexion ROM with peak hip and knee angles during the preparation (r = -.23 to .36, P > .05) and landing (r = -.20 to .24, P > .05) phases of the jump. There was no association of hip abduction strength with peak hip and knee angles during the landing phase of the jump (r = -.28 to .16, P > .05).

CONCLUSION

Hip abductors strengthening, correction of foot misalignments, and increasing ankle dorsiflexion ROM may not prevent excessive hip and knee movements during a classical ballet single-leg jump in amateur dancers.

Does forced or compensated turnout lead to musculoskeletal injuries in dancers? A systematic review on the complexity of causes

Injury prevalence in dancers is high, and misaligned turnout (TO) is claimed to bear injury risk. This systematic review aimed to investigate if compensating or forcing TO leads to musculoskeletal injuries. A systematic literature review was conducted according to the PRISMA Guidelines using the databases of PubMed, Embase, Emcare, Web of Science, Cochrane Library, Academic Search Premier, and ScienceDirect. Studies investigating the relationship between compensated or forced TO and injuries in all genders, all ages, and levels of dancers were included. Details on misaligned TO measurements and injuries had to be provided. Screening was performed by two researchers, data extraction and methodological quality assessment executed by one researcher and checked by another. 7 studies with 1293 dancers were included. Methodological quality was low due to study designs and a general lack of standardised definition of pathology and methods of assessment of misaligned TO. The studies investigating the lower extremities showed a hip-focus only. Non-hip contributors as well as their natural anatomical variations were not accounted for, limiting the understanding of injury mechanisms underlying misaligned TO. As such no definite conclusions on the effect of compensating or forcing TO on musculoskeletal injuries could be made. Total TO is dependent on complex motion cycles rather than generalised (hip) joint dominance only. Objective dual assessment of maximum passive joint range of motion through 3D kinematic analysis in combination with physical examination is needed to account for anatomical variations, locate sites prone to (overuse)injury, and investigate underlying injury mechanisms.

Patellofemoral pain, body morphology and alignment in female pubertal dancers: One-year follow-up

The aim of this study was to assess changes in body morphology, anatomical alignment and prevalence of patellofemoral pain (PFP) in young female dancers along one year of pubertal growth, and to identify the risk factors related to PFP in these young dancers. Both legs of 60 dancers were evaluated during grade 7 and again after 1-year. At each of these points in time, the dancers were interviewed concerning their background, and anthropometric measurements, lower-limb physical examinations and knee ultrasound scans were performed. Morphological parameters changed significantly from baseline to follow-up. PFP was found in 53.3% of the dancers' knees at baseline. At follow-up, 55.4% of the asymptomatic knees at baseline developed PFP, and only 9.4% of the symptomatic knees at baseline recovered. Lower BMI was identified among dancers who developed PFP during follow-up compared with dancers with no PFP, either at baseline or at follow-up. A positive grinding and positive Patellar Inhibition Test (PIT) were found to be risk factors for PFP at follow-up. A high prevalence of young dancers suffered PFP, from injuries they sustained mostly during the 1-year of dance practice. Parameters predisposing the dancers to PFP should be identified at early stages of dance class.

Comparable patient-reported outcomes in females with or without joint hypermobility after hip arthroscopy and capsular plication for femoroacetabular impingement syndrome

Hip arthroscopy is widely utilized to treat femoroacetabular impingement syndrome (FAIS). In order to evaluate the postoperative clinical and functional outcomes at 2-year follow up in patients with and without benign joint hypermobility syndrome following hip arthroscopy with capsular plication for FAIS, consecutive female patients with generalized ligamentous laxity undergoing primary hip arthroscopy with complete T-capsulotomy closure via plication for FAIS were prospectively identified. Patients were matched in a 4:1 ratio based on Beighton-Horan joint mobility index (BHJMI) then classified into no generalized joint laxity (NGJL, Score<4) or generalized joint laxity cohort (GJL, Score=4). Patient and surgical-related factors were analyzed using univariate and paired analysis with statistical significance set at a = 0.05. A total of 125 female patients were included in the study: 25 generalized joint laxity (GJL) patients and 100 matched to age, sex and BMI (NGJL cohort). The results demonstrated that there were no significant differences between demographics, preoperative range of motion, or radiographic analysis on univariate analysis. There was no statistical difference in postoperative range of motion between groups, though both groups demonstrated significant increases in postoperative flexion and postoperative internal rotation following hip arthroscopy. Paired analysis demonstrated no significant difference in HOS-SS, HOS-ADL, mHHS or VAS-pain, while GJL patients reported significantly greater patient satisfaction score at 2-years follow-up (p=0.007). In summary, hip arthroscopy with capsular plication is a highly effective treatment for FAIS in patients with and without generalized joint laxity. In our analysis, patients with and without generalized joint laxity demonstrated statistically similar and significant improvement in outcomes.

Dynamic Neuro-Cognitive Imagery (DNITM) Improves Developpé Performance, Kinematics, and Mental Imagery Ability in University-Level Dance Students

Dance requires optimal range-of-motion and cognitive abilities. Mental imagery is a recommended, yet under-researched, training method for enhancing both of these. This study investigated the effect of Dynamic Neuro-Cognitive Imagery (DNITM) training on developpé performance (measured by gesturing ankle height and self-reported observations) and kinematics (measured by hip and pelvic range-of-motion), as well as on dance imagery abilities. Thirty-four university-level dance students (M age = 19.70 ± 1.57) were measured performing three developpé tasks (i.e., 4 repetitions, 8 consecutive seconds hold, and single repetition) at three time-points (2 × pre-, 1 × post-intervention). Data were collected using three-dimensional motion capture, mental imagery questionnaires, and subjective reports. Following the DNITM intervention, significant increases (p < 0.01) were detected in gesturing ankle height, as well as in hip flexion and abduction range-of-motion, without significant changes in pelvic alignment. These gains were accompanied by self-reported decrease (p < 0.05) in level of difficulty experienced and significant improvements in kinesthetic (p < 0.05) and dance (p < 0.01) imagery abilities. This study provides evidence for the motor and non-motor benefits of DNITM training in university-level dance students.

Association between coping skills, past injury and hip pain and function in adolescent elite female ballet dancers

OBJECTIVES

The purpose of this study was to investigate the relationship between coping skills and current hip pain and function scores in ballet dancers. Secondly, we examined the relationship between coping skills and past injuries. Thirdly, we investigated the association between past injuries and current pain and function scores.

METHODS

This was a cross-sectional observational study. Twenty-six young elite female dancers (mean age 15.9 years, range 14-17 years) participated. Participants completed surveys indicating past injury history, rating pain and function on the short International Hip Outcome Tool (iHOT-12), and assessing coping skills on the Athletic Coping Skills Inventory Score (ACSI-28). Independent t-tests, Cohen's d, effect size, chi-square and correlation coefficient and determination analyses were conducted.

RESULTS

There was no significant relationship between iHOT-12 scores and ACSI-28 scores (r = -0.250, p = 0.087). There was no significant difference (p = 0.289) in past injuries comparing those with ACSI-28 scores above and below the mean ACSI-28. A significant moderate negative correlation was detected between both iHOT-12 scores and total past injuries (r = -0.609, p < 0.001), and iHOT-12 scores and past non-hip injuries (r = -0.628, p < 0.001).

CONCLUSION

Past injuries may influence current hip pain and function in young female dancers. Correlation determination (r²) indicated that 37% of current pain and function scores were explained by total past injuries in a small group of young high-level ballet dancers. Further research should engage a prospective design to investigate the predictive ability of findings.

The association between menarche, intensity of training and passive joint ROM in young pre-professional female dancers: A longitudinal follow-up study

OBJECTIVES

To determine the association between the status of menarche (yes/no), the intensity of training and the potential to improve passive joint range of motion (ROM) over a 12-month period of dance training.

DESIGN

Prospective cohort study.

SETTING

Dance studio.

PARTICIPANTS

Fifty-nine female dancers aged 12.8 ± 0.5.

MAIN OUTCOME MEASURES

The dancers were asked about their dance intensity and screened for anthropometric parameters and passive joint ROM in Grades 7 and 8.

RESULTS

Along the 12 months of dance training, we found significantly increased ankle-foot en-pointe, hip abduction, and hip external rotation (ER); significantly decreased hip internal rotation (IR); and significant increased hip ER:IR ratio. In Grade 7, 26 dancers (44.1%) reached menarche (Yes menarche); in Grade 8 an additional 23 dancers (39.0%) reached menarche (No/Yes menarche); and 10 dancers (16.9%) had not reached menarche (No menarche). MANOVA (mixed models) with repeated measures to compare joint ROM between the three menarche groups (Yes; No/Yes; No), with h/week dance practice as a co-variant, showed that hip ER, ankle-foot en-pointe, and ER:IR were significantly correlated with h/week in all three menarche groups.

CONCLUSIONS

Most passive joint ROM can be improved over 12 months of dancing around the age onset of menarche. H/week of dance practice is a main factor contributing to improved hip ER, ankle-foot en-pointe and ER/IR ratio.

Ultrasonography findings and physical examination outcomes in dancers with and without patellofemoral pain

OBJECTIVES

To identify whether a physical examination for patello-femoral pain (PFP) is related to ultrasonography findings at the knee, and to identify possible factors related to PFP in young dancers.

METHODS

Sixty-seven young female dancers (7th grade, aged 12.8 ± 0.5) from three schools with identical special dance programs were included in the study. All the dancers were interviewed for demographic details, dance background, and training intensity; were evaluated for anthropometric measurements; underwent physical examination of both knees for PFP and for knee range of motion (ROM); and, had ultrasonography assessment for pathologies and of anatomical parts of their knees.

RESULTS

PFP was found in 54.5% of the 134 knees physically examined. In ultrasonography assessment, infra-articular effusion was found in 46.2% of the knees examined. H/week of dance practice was significantly higher among dancers with PFP (in both knees) compared with dancers with no PFP (p < .05). Knees with PFP had a significantly higher prevalence of intra articular effusion (p = .018) and higher prevalence of genu-recurvatum (p = .042). Knees with PFP had significantly greater growth plate width-anterior tibial tuberosity (p = .022) and a greater bony trochlear groove angle (p = .048).

CONCLUSION

This study describes the relationship between physical examination for PFP and the sonographic findings, and the factors related to knee injuries. The results showed a high prevalence of PFP and intra articular knee effusion among young dancers at the age of 12-13 years; and, that the number of hours of practice and anatomical structure are related to PFP. Our results should alert physicians, physiotherapists, athletic trainers and dance teachers to the need for devising modifications of training and injury prevention strategies from a young age (<12 years old).

Overuse Injuries in Professional Ballet: Influence of Age and Years of Professional Practice

Background:

In spite of the high rate of overuse injuries in ballet dancers, no studies have investigated the prevalence of overuse injuries in professional dancers by providing specific diagnoses and details on the differences in the injuries sustained as a function of age and/or years of professional practice.

Hypothesis:

Overuse injuries are the most prevalent injuries in ballet dancers. Professional ballet dancers suffer different types of injuries depending on their age and years of professional practice.

Study Design:

Descriptive epidemiology study.

Methods:

This descriptive epidemiological study was carried out between January 1, 2005, and October 10, 2010, regarding injuries sustained by professional dancers belonging to the major Spanish ballet companies practicing classical, neoclassical, contemporary, and Spanish dance. The sample was distributed into 3 different groups according to age and years of professional practice. Data were obtained from the specialized medical care the dancers received from the Trauma and Orthopaedic Surgery Service at Fremap in Madrid. The dependent variable was the study of the injury.

Results:

A total of 486 injuries were identified over the study period, with overuse injuries being the most common etiology (P < .0001); these injuries were especially prevalent in junior professional dancers practicing classical ballet and veteran dancers practicing contemporary ballet (P = .01). Specifically, among other findings, stress fractures of the base of the second metatarsal (P = .03), patellofemoral syndrome, and os trigonum syndrome were more prevalent among junior professionals (P = .04); chondral injury of the knee in senior professionals (P = .04); and cervical disc disease in dancers of intermediate age and level of experience.

Conclusion:

Overall, overuse injuries were more prevalent in younger professionals, especially in women. This finding was especially true for the more technical ballet disciplines. On the other hand, in the athletic ballet disciplines, overuse lesions occurred mainly in the more senior professionals.

Clinical Relevance:

This study provides specific clinical diagnoses obtained through physical examination as well as details on the different injury types sustained as a function of age and/or years of professional practice, an important aspect for ballet and sports practice in general.

Snapping hip syndrome: systematic review of surgical treatment

The snapping hip (SH) syndrome is characterised by an audible snapping, often accompanied by pain, which usually occurs with the flexion and extension of the hip during exercise or ordinary daily activities.The causes of SH can be classified as external, internal and intraarticular. The prevalence of asymptomatic SH in the population is unknown and the incidence of symptomatic cases is not well-defined. The painless snapping in the hip is common in the general population; the symptomatic SH with debilitating pain and weakness is often seen in those who take part in activities such as ballet and running hurdles.The clinician's goal is to determine the cause and treat patients who have symptomatic SH so that they may return to their activities or to athletic peak performance.Most patients with SH can be treated conservatively. However, surgery may be indicated if the condition becomes chronically symptomatic. Arthroscopy may prove useful in the treatment of intraarticular lesions that are causing discomfort. Various techniques have been described with different grades of success. The aim is to achieve the least invasive procedure with the lowest potential complications that corrects the painful snapping, according to the patient's characteristics.The purpose of this systematic review is to clarify the results of the surgical treatment of SH, after the failure of the conservative treatment.

Large strengthening effect of a hip-flexor training programme: a randomized controlled trial

PURPOSE

To investigate the effect on hip-flexion strength of a 6-week hip-flexor training programme using elastic bands as resistance. We hypothesized that the training group, compared to a control group, would increase their hip-flexion strength more.

METHODS

Thirty-three healthy subjects (45 % females), 24(5) years of age, were included in a randomized controlled trial and allocated to heavy strength training of the hip-flexor muscles or to control (no strength training). Strength training of the hip-flexors (dominant leg) was performed three times 10 min per week for 6 weeks. The strength training group progressed from 15 repetition maximum (RM) (week 1) to 8 RM (week 6). Isometric hip-flexion strength (primary outcome) was measured by a blinded assessor using a reliable test procedure.

RESULTS

In the strength training group, the isometric hip-flexion strength of the trained leg increased by 17 %, (p < 0.001). The between-group difference in hip-flexion strength change in the trained leg (dominant leg, training group) versus the non-trained leg (dominant leg, control group) was significantly different from baseline to follow-up, corresponding to a mean change of 0.34 (95 % CI 0.17-0.52) Nm/kg, in favour of the strength training group (p < 0.001).

CONCLUSION

Simple hip-flexor strength training using elastic bands as external loading, for only 6 weeks, substantially improves hip-flexor muscle strength. This simple exercise programme seems promising for future prevention and treatment of acute and longstanding hip-flexor injuries, such as acute rectus femoris injuries and longstanding iliopsoas-related pain and impingement.

LEVEL OF EVIDENCE

I.

Overuse Injuries in Professional Ballet: Injury-Based Differences Among Ballet Disciplines

Background

Despite overuse injuries being previously described as the most frequent in ballet, there are no studies on professional dancers providing the specific clinical diagnoses or type of injury based on the discipline.

Hypothesis

Overuse injuries are the most frequent injuries in ballet, with differences in the type and frequency of injuries based on discipline.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

This was a descriptive cross-sectional study performed between January 1, 2005, and October 10, 2010, on injuries occurring in professional dancers from leading Spanish dance companies who practiced disciplines such as classical, neoclassical, contemporary, and Spanish ballet. Data, including type of injury, were obtained from specialized medical services at the Trauma Service, Fremap, Madrid, Spain.

Results

A total of 486 injuries were evaluated, a significant number of which were overuse disorders (P < .0001), especially in the most technically demanding discipline of classical ballet (82.60%). Injuries were more frequent among female dancers (75.90%) and classical ballet (83.60%). A statistically significant prevalence of patellofemoral pain syndrome was found in the classical discipline (P = .007). Injuries of the adductor muscles of the thigh (P = .001) and of the low back facet (P = .02) in the Spanish ballet discipline and lateral snapping hip (P = .02) in classical and Spanish ballet disciplines were significant.

Conclusion

Overuse injuries were the most frequent injuries among the professional dancers included in this study. The prevalence of injuries was greater for the most technically demanding discipline (classical ballet) as well as for women. Patellofemoral pain syndrome was the most prevalent overuse injury, followed by Achilles tendinopathy, patellar tendinopathy, and mechanical low back pain.

Clinical Relevance

Specific clinical diagnoses and injury-based differences between the disciplines are a key factor in ballet.

Sonography of sports injuries of the hip

CONTEXT

Sports-related injuries of the hip are a common complaint of both competitive and recreational athletes of all ages. The anatomic and biomechanical complexity of the hip region often cause diagnostic uncertainty for the clinicians evaluating these injuries. Therefore, obtaining additional diagnostic information is often crucial for providing injured athletes with a prompt and accurate diagnosis so they can return to activity as soon as possible. Musculoskeletal ultrasound is becoming increasingly important in evaluating and treating sports-related injuries of the hip.

EVIDENCE ACQUISITION

The PubMed database was searched in May of 2013 for English-language articles pertaining to sonography of sports injuries of the hip using the following keywords in various combinations: musculoskeletal, ultrasound, hip, hip sonography, and sports.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Musculoskeletal ultrasound is currently being used for both diagnosis and treatment in a wide range of acute and chronic conditions affecting the hip, including tendinosis, tendon/muscle strains, ligamentous sprains, enthesopathies, growth plate injuries, fractures, bursitis, effusions, synovitis, labral tears, and snapping hip. Therapeutically, it is used to guide injections, aspirations, and biopsies.

CONCLUSION

Musculoskeletal ultrasound use is expanding and will likely continue to do so as more clinicians realize its capabilities. Characteristics, including accessibility, portability, noninvasiveness, dynamic examination, power Doppler examination, and low cost highlight the potential of ultrasound.

The usefulness of performance matrix tests in locomotor system evaluation of girls attending a ballet school - preliminary observation

[Purpose] Learning ballet is connected with continuous use of the locomotor system while subjecting it to high loads. Therefore, we conducted some research defining the appearance of weak links in the motor system, in order to eliminate the risk of injury. [Methods] Fifty-two female students of a ballet school were examined. To identify weak links, low-threshold Performance Matrix tests were performed. An analysis of weak link occurrence in the locomotor system was carried out, using two way analysis of variance ANOVA Tukey's HSD test, clustering methods and Principal Component Analysis (PCA). [Results] The average age of the subjects was 11.64±0.53 years (mean ± standard deviation), their average body height was 151.1±7.5 cm, their average body weight was 35.92±5.41 kg, and their average time of learning at ballet school was 2.17±0.65 years. We found that there were significant differences in weak links occurrence in the motor system of every girl examined. [Conclusions] Weak links were found in every location of the motor system. Our results show that the influence of weak link location is essentially different from their occurrence, and that learning ballet has a significantly different impact on the number of weak links in different locations.

Injuries in female dancers aged 8 to 16 years

CONTEXT

Most studies of injured dancers have been carried out on professional adult dancers; data on young, nonprofessional injured dancers are sparse.

OBJECTIVE

To identify the types of injuries sustained by recreational dancers and to examine their association with age, joint range of motion, body structure, age at menarche, presence of anatomic anomalies, and physical burden (i.e., practice hours en pointe).

DESIGN

Descriptive epidemiology study.

SETTING

The Israel Performing Arts Medicine Center, Tel Aviv.

PATIENTS OR OTHER PARTICIPANTS

A total of 569 injured female dancers, aged 8 to 16 years.

MAIN OUTCOME MEASURE(S)

Dependent variables were 61 types of current injuries that were later classified into 4 major categories: knee injuries, foot and ankle tendinopathy, back injuries, and other injuries. Independent variables were age, joint range of motion, body size and shape, age at menarche, anatomic anomalies, and dance discipline (e.g., hours of practice per week en pointe).

RESULTS

At least 1 previous injury had been sustained by 42.4% of the dancers. The most common injuries involved the knee (40.4%), followed by other injuries (23.4%). The relative frequency of back injuries and tendinopathy decreased with age, whereas knee injuries increased. Types of injuries were significantly associated with ankle plantar flexion, hip external rotation, hip abduction, and knee flexion. Multinomial regression analysis revealed only 3 predictive variables (with other as baseline), all for back injury: scoliosis, age, and hip external rotation.

CONCLUSIONS

Joint range of motion and scoliosis may signal the potential for future injury. Young dancers (less than 10 years of age) should not be exposed to overload (especially of the back) or extensive stretching exercises.

Correlation of clinical and magnetic resonance imaging findings in hips of elite female ballet dancers

PURPOSE

To understand why professional female ballet dancers often complain of inguinal pain and experience early hip osteoarthritis (OA). Goals were to examine clinical and advanced imaging findings in the hips of dancers compared with those in a matched cohort of nondancers and to assess the femoral head translation in the forward split position using magnetic resonance imaging (MRI).

METHODS

Twenty professional female ballet dancers and 14 active healthy female individuals matched for age (control group) completed a questionnaire on hip pain and underwent hip examination with impingement tests and measurement of passive hip range of motion (ROM). All had a pelvic 1.5 T MRI in the back-lying position to assess femoroacetabular morphologic features and lesions. For the dancers, additional MR images were acquired in the split position to evaluate femoroacetabular congruency.

RESULTS

Twelve of 20 dancers complained of groin pain only while dancing; controls were asymptomatic. Dancers' passive hip ROM was normal. No differences in α neck angle, acetabular depth, acetabular version, and femoral neck anteversion were found between dancers and controls. MRI of dancers while performing splits showed a mean femoral head subluxation of 2.05 mm. MRI of dancers' hips showed labral tears, cartilage thinning, and herniation pits, located in superior and posterosuperior positions. Lesions were the same for symptomatic and asymptomatic dancers. Controls had proportionally the same number of labral lesions but in an anterosuperior position. They also had 2 to 3 times fewer cartilage lesions and pits than did dancers.

CONCLUSIONS

The results of our study are consistent with our hypothesis that repetitive extreme movements can cause femoral head subluxations and femoroacetabular abutments in female ballet dancers with normal hip morphologic features, which could result in early OA. Pathologic changes seen on MRI were symptomatic in less than two thirds of the dancers.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Comparison of postural stability between injured and uninjured ballet dancers

BACKGROUND

Ballet movements require a limited base of support; thus, ballet dancers require a high level of postural control. However, postural stability in ballet dancers is still unclear and needs to be understood.

PURPOSE

To evaluate ballet dancers' postural stability in performing single-leg standing, the en pointe task, and the first and fifth positions and to determine differences in task performance among healthy nondancers, healthy dancers, and dancers with ankle sprains.

STUDY DESIGN

Controlled laboratory study.

METHODS

Injured dancers, uninjured dancers, and nondancers were recruited for this study (N = 33 age-matched participants; n= 11 per group). The tasks tested were single-leg standing with eyes open and closed, first position, fifth position, and en pointe. Center of pressure parameters were calculated from the ground-reaction force collected with 1 force plate. Analysis of variance was used to assess the differences of center of pressure parameters among 3 groups in single-leg standing; independent t test was used to examine the differences of center of pressure parameters between injured and uninjured dancers.

RESULTS

During single-leg standing, injured dancers had significantly greater maximum displacement in the medial-lateral direction and total trajectory of center of pressure, compared with the uninjured dancers and nondancers. During the first and fifth positions, the injured dancers demonstrated significantly greater standard deviation of center of pressure position in the medial-lateral and anterior-posterior directions, compared with the uninjured dancers. During en pointe, the injured dancers had significantly greater maximum displacement in the medial-lateral direction and the anterior-posterior direction, compared with the uninjured dancers.

CONCLUSION

The injured and uninjured dancers demonstrated differences in postural stability in the medial-lateral direction during single-leg standing and the ballet postures. Although the injured dancers received ballet training, their postural stability may still be inferior to that of the nondancers.

CLINICAL RELEVANCE

This study is a first step in understanding that injured ballet dancers do not have the same postural stability as uninjured dancers and that it is even inferior to that of nondancers, which is important to understand for further study on rehabilitation. The future development of effective balance training programs for ballet dancers with ankle injuries should emphasize improvements in medial-lateral directional balance.

Dance-Related Injury

Although dance medicine has derived extensive knowledge from sports medicine, some aspects covered in the practice of dance medicine are unique to this field. Acute and overuse injuries must be analyzed within the scope of associated mechanisms of injury, mainly related to the practice of specific dance techniques. Even though most available medical literature concerning dance medicine is specific to ballet-related conditions, many of the concepts covered here and in other articles can be helpful in the treatment and diagnosis of participants in other dance disciplines. Continued research is expanding the knowledge on injury patterns of different dance disciplines. It is the experience of dance practitioners that dancers are quite in touch with their bodies; thus, when their ailments are systematically analyzed, and underlying cause can usually be identified. In this sense, it is evident that the principles of dance medicine and rehabilitation allow the practitioner to arrive at a diagnosis and treat the underlying causes to prevent reinjury, ameliorate sequelae from injury, and minimize residual deficits after injury.

The Dancer as a Performing Athlete

The physical demands placed on dancers from current choreography and performance schedules make their physiology and fitness just as important as skill development. However, even at the height of their professional careers, dancers' aerobic power, muscular strength, muscular balance, bone and joint integrity are the 'Achilles heels' of the dance-only selection and training system. This partly reflects the unfounded view, shared by sections of the dance world, that any exercise training that is not directly related to dance would diminish dancers' aesthetic appearances. Given that performing dance itself elicits only limited stimuli for positive fitness adaptations, it is not surprising that professional dancers often demonstrate values similar to those obtained from healthy sedentary individuals of comparable age in key fitness-related parameters. In contrast, recent data on male and female dancers revealed that supplementary exercise training can lead to improvements of such fitness parameters and reduce incidents of dance injuries, without interfering with key artistic and aesthetic requirements. It seems, however, that strict selection and training regimens have succeeded in transforming dance to an activity practised by individuals who have selectively developed different flexibility characteristics compared with athletes. Bodyweight targets are normally met by low energy intakes, with female dance students and professional ballerinas reported to consume below 70% and 80% of the recommended daily allowance of energy intake, respectively, while the female athlete 'triad' of disordered eating, amenorrhoea and osteoporosis is now well recognised and is seen just as commonly in dancers. An awareness of these factors will assist dancers and their teachers to improve training techniques, to employ effective injury prevention strategies and to determine better physical conditioning. However, any change in the traditional training regimes must be approached cautiously to ensure that the aesthetic content of the dance is not affected by new training techniques. Since physiological aspects of performing dance have been viewed primarily in the context of ballet, further scientific research on all forms of dance is required.

MR imaging of sports-related hip disorders

Hip arthroscopy is being used increasingly for the diagnosis and treatment of hip disorders. MR imaging performed with appropriate technical considerations may aid not only in preoperative planning but in the appropriate selection of patients, which tends to lead to better postoperative results. Although the painful hip is imaged most commonly by radiography, MR imaging is considered the next imaging test of choice for evaluation of most common hip abnormalities in athletes, including labral injuries, ligament injuries, osteochondral injuries, fractures, bursitis, and musculotendinous injuries. MR arthrography can be a particularly useful technique for dedicated assessment of hip joint internal derangements.

Medical and rehabilitation issues in classical ballet

Classical ballet is a demanding professional occupation, with participants who are often underserved in terms of accurate diagnosis and appropriate comprehensive medical care. The view that follows is designed to be as global and insightful as published to date. Specific rehabilitation considerations, dance mechanics, idiosyncratic differential diagnosis, and personality and equipment issues are discussed, and a rational view of dogma is presented.

The young dancer

The injuries that are prevalent in and unique to dancers have their origins inextricably linked to faulty technique or poor biomechanics, combined with other risk factors. It is this combination of factors that must be addressed when considering diagnosis, treatment, and rehabilitation. For the dancer to return to full activity with minimal risk of recurrent injury, neuromuscular re-education is mandatory. This process best entails using a team approach, accessing the resources of healthcare professionals and those who train the dancer on a daily basis. In some cases, parents also may need to be involved. Communication, interaction, and mutual understanding among these groups will assist the dancer in regaining and maintaining health.

Foot and ankle injuries in dance

Acute traumatic injuries are common in ballet dancers. A careful history, thorough examination, and appropriate imaging should allow for the diagnosis of most problems. The clinician must have a high index of suspicion for occult bony injuries, especially if the patient fails to recover as expected. Aggressive treatment of the sprained ankle is essential to maintain foot and ankle mobility and prevent prolonged disability and subsequent overuse injuries. Kinetic chain dysfunctions are common in ballet dancers with overuse injuries and commonly follow ankle sprains. They may represent a secondary phenomenon that developed in response to the compensatory movement changes caused by the initial injury. It is important to remember, however, that these dysfunctions may have been long standing and a causative factor in the injury. Regardless of the time of onset of the dysfunction, residual kinetic chain dysfunction associated with incomplete rehabilitation of an injury may predispose the dancer to further injuries. Untreated dysfunctions at one site in the kinetic chain may predispose to compensatory dysfunction at other sites in the chain. Accordingly, it is essential to thoroughly examine the entire chain for functional movements when dealing with an injury, because identification and treatment of the kinetic chain dysfunction is important in the rehabilitation of the dancing athlete. Kinetic chain dysfunctions are common in injured ballet dancers and may be a cause of repeated injury. Why then are these dysfunctions left untreated? Medical personnel caring for dancers are sometimes guilty of tunnel vision, and focus solely on the injured site without considering what is happening at other sites in the kinetic chain. This oversight is compounded when the physicians or therapists are satisfied with discovering simply what injury has occurred rather than asking why the injury has occurred. The significance of kinetic chain dysfunctions is only just beginning to be recognized, and many examiners are not aware of the relationship between abnormal motion and injury. Generally, people see only what they look for, and they look only for what they know. Kinetic chain dysfunctions can easily be detected with simple tests of functional movement if the examiners include these tests in their assessment of the injured dancer. As long as clinicians are either unaware of or unwilling to perform these tests, these dysfunctions will remain untreated and may put the dancer at risk of failed rehabilitation or predispose them to further injury.

Can 16-18-year-old elite ballet dancers improve their hip and ankle range of motion over a 12-month period?

OBJECTIVE

To determine the effect of a 12-month intensive ballet training regimen on hip and ankle range of motion in male and female, first- and second-year professional dancers.

DESIGN

12-month longitudinal follow-up.

SETTING

National classical ballet school in Australia.

PARTICIPANTS

28 female and 20 male full-time ballet students with a mean +/- 1 SD, ages 16.8 +/- 0.8 and 17.7 +/- 1.2 years, respectively.

MAIN OUTCOME MEASURES

Degrees of range of motion of left and right sides for the following movements: standing plié in parallel-passive ankle dorsiflexion (DF); standing turnout in the balletic first position--lower leg external rotation (LLER); supine hip external rotation (ER); supine hip internal rotation (IR). An additional range of motion was calculated: external rotation below the hip joint (BHER) derived by subtracting hip ER from LLER.

MAIN RESULTS

In all subjects combined, hip and ankle ranges increased statistically on the right. However, the amount was generally minimal and most at the borderline of the amount of error associated with the measurement tool. While there was no change in LLER, there was a decrease in BHER. There were no overall gender differences, and year differences existed only for left hip ER and total hip ER with first-year dancers showing significant improvements in these ranges. For DF and sum of hip IR, first-year males and second-year females had increases in range. There was a negative relationship between baseline range and the amount of change over the 12 months.

CONCLUSIONS

Dancers ages 16-18 years who enter full-time ballet training did not augment their ankle dorsiflexion to any appreciable degree. Some, but certainly not all, increased their hip active external rotation over 12 months without increasing their total lower limb turnout. Hip ER was more likely to improve in the first-year rather than second-year student in this elite full-time training school.

Hip and ankle range of motion and hip muscle strength in young female ballet dancers and controls

OBJECTIVES

To compare the hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls.

METHODS

Subjects were 77 dancers and 49 controls (mean (SD) age 9.6 (0.8) and 9.6 (0.7) years respectively). Supine right active hip external rotation (ER) and internal rotation (IR) were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. The measure of ER achieved from below the hip during turnout (non-hip ER) was calculated by subtracting hip ER range from turnout range, and hip ER:IR was derived by dividing ER range by IR range. Range of right weight bearing ankle dorsiflexion was measured in a standing lunge using two methods: the distance from the foot to the wall (in centimetres) and the angle of the shank to the vertical via an inclinometer (in degrees). Right calf muscle range was measured in weight bearing using an inclinometer. A manual muscle tester was used to assess right isometric hip flexor, internal rotator, external rotator, abductor, and adductor strength.

RESULTS

Dancers had less ER (p<0.05) and IR (p<0.01) range than controls but greater ER:IR (p<0.01). Although there was no difference in turnout between groups, the dancers had greater non-hip ER. Dancers had greater range of ankle dorsiflexion than controls, measured in both centimetres (p<0.01) and degrees (p<0.05), but similar calf muscle range. After controlling for body weight, controls had stronger hip muscles than dancers except for hip abductor strength which was similar. Regression analyses disclosed a moderate relation between turnout and hip ER (r = 0.40). There were no significant correlations between range of motion and training years and weekly training hours.

CONCLUSIONS

Longitudinal follow up will assist in determining whether or not hip and ankle range in young dancers is genetically fixed and unable to be improved with further balletic training.

Applications of musculoskeletal sonography

To successfully examine the musculoskeletal system sonographically, one must understand the normal musculoskeletal anatomy and function and be aware of the abnormal processes that affect the musculoskeletal structures. The goal of this review article is to provide a systematic approach to sonographic examination of the musculoskeletal system. The general sonographic appearances of normal and abnormal muscles, tendons, ligaments, bursae, and nerves are reviewed. The article then applies this general information to specific clinical applications by reviewing the normal anatomy of and specific pathologic conditions that affect the shoulder, elbow, hand, wrist, hip, knee, ankle, and foot.

Treatment of iliopsoas syndrome with a hip rotation strengthening program: a retrospective case series

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To review the effectiveness of a home-based rehabilitation program in the treatment of iliopsoas syndrome.

BACKGROUND

Conservative management strategies for iliopsoas bursitis (syndrome) have not been well documented in the literature. This study relates the outcome of an exercise program (hip rotation exercises and stretching) to address clinical deficiencies observed in iliopsoas syndrome.

METHODS AND MEASURES

A retrospective chart review and phone follow-up were done to determine pain and activity limitation for 9 patients (mean age, 35.6 +/- 12.7 years; 8 women, 1 man) before and after application of the rehabilitation program. As a group, symptoms of iliopsoas syndrome were present for a mean of 12.6 (+/- 18.4) months prior to diagnosis and rehabilitation. Activity restrictions related to presenting symptoms were measured using a 4-point ordinal scale (from a score of 1 [pain and unable to do sport] to a score of 4 [pain-free, full activity]).

RESULTS

Pain and function improvement occurred in 7 of 9 (77%) patients. Five patients improved by at least 2 pain/activity levels at the time of follow-up (13.2 +/- 9.8 months following diagnosis); all but 2 patients were able to return to full activity.

CONCLUSIONS

This study gives preliminary evidence that a specific exercise regimen incorporating hip rotation might improve function and reduce pain for patients with iliopsoas syndrome.

A ballet dancer with chronic hip pain due to a lesser trochanter bony avulsion: the challenge of a differential diagnosis

Physical therapy assessment involves confirmation of a medical diagnosis. To help discuss this process, this case report is presented regarding a ballet dancer who experienced 6 years of chronic hip pain and dysfunction. Many diagnostic tests and surgical procedures were performed by various physicians in search of a diagnosis. Physical therapy assessments did not support the working diagnoses, and treatment given according to evaluation findings was not effective. Initial hip radiographs revealed a bony ossicle at the lesser trochanter, which was overlooked. Hip radiographs taken 5 years later revealed the same bony ossicle. Ultimately, surgical removal of the ossicle eliminated the hip pain, and the patient returned to full activity and dance again. With the attempt to confirm the patient's diagnosis, the physical therapy approach to problem solving is discussed. This case gives an example where it is important to question the physician's diagnosis when the physical therapy assessment and treatment response do not support it. it is also evident that an in-depth physical therapy assessment may be self-limiting if pathology has not been ruled out properly by the physician.

Delayed diagnosis of fatigue fractures in the elderly

A retrospective study was made of 30 stress fractures in elderly patients engaged in noncompetitive sporting activities, mostly marching and running. Fractures were located exclusively in the lower limbs. In many cases the diagnosis was delayed and in several cases was incorrect because the stress fracture was mistaken for other conditions. Given that the number of senior citizens engaged in active life and sporting activities is constantly growing, physicians should be aware of this type to ensure early diagnosis and appropriate treatment.

Functional Biomechanical Analysis of the Pilates-Based Reformer during Demi-Plié Movements

The Pilates-based reformer is used by dancers for training and for injury rehabilitation. Knee kinematics and applied forces during demi-plié in fifth and in first positions were analyzed while dancers performed the motions (a) standing, (b) on the reformer equipped with two springs, and (c) on the reformer equipped with four springs. The highest forces, normalized to body weight, were obtained for the standing demi-plié, while the largest knee flexion angles occurred on the reformer with four springs. Greater range of motion was achieved in first position than in fifth, and females exhibited greater extension and higher normalized forces than males, It was also noted that force/knee angle relationships for the standing demi-plié and for the reformer tests were quite different. Reformer forces were totally dependent on the knee angle, whereas the forces during the standing demi-plié depended on the acceleration of the dancer's center of gravity.

Total and regional bone mineral content in Spanish professional ballet dancers

Total body bone mineral content (TBBMC) and regional bone mineral content (BMC) was measured in the members of the Spanish National Dance Company (15 female, mean age 25.1 +/- 3.8 years, and 15 male, mean age 28.2 +/- 2.1 years) and in 30 controls (15 women, mean age 26.1 +/- 1.8 years, and 15 men, mean age 28.0 +/- 1.5 years). Ca, P, and Mg intake were greater in the group of ballet dancers than in controls analysis of variance (ANOVA, all P < 0.0001). BMC was similar in the group of ballet dancers and controls except in the trunk without pelvis (P < 0.001). Both male and female dancers weighed less than controls (P < 0.05). The BMC of the male dancers was less than that of male controls only in the trunk (P < 0.05) and in the trunk without pelvis (P < 0.005); BMC was lower in female dancers than in female controls only in the arms and in the trunk without pelvis (P < 0.05 and P < 0.005, respectively). TBBMC, adjusted for weight and age, was correlated partially with caloric intake (kcal/day) and with Ca, P, Mg, and Zn intake (g/day), and yielded significant differences between the dancers and controls only in P intake (P < 0.01), and between male dancers and male controls only in caloric intake and in Ca, P, and Zn intake (all P < 0.01, except for Ca, P < 0.05). The lower trunk bone mass observed in the female dancers is a risk factor for eventual osteoporosis.

Injury in ballet: a review of relevant topics for the physical therapist

Currently, there is a need for a review of the literature on ballet injury as it pertains to the physical therapist. Relatively few articles have reviewed ballet injury prevalence and mechanisms of injury. The purpose of this paper was to provide a thorough literature review of the prevalence of ballet injury and mechanisms of injury. Environmental factors and footwear relating to ballet injury were also reviewed. The literature indicated that 65-80% of ballet injuries are in the lower extremity, 10-17% occur in the vertebral column, and most of the remaining percentage are upper limb injuries (5-15%). The etiology of common lower limb conditions included an incorrect turnout; soft tissue imbalances; reduced quadriceps performance; "rolling in of the foot;" inversion sprains; and frequent pliés, pointé, and demipointé work. Spinal conditions were reported to result from hyperextension and hyperlordosis of the lumbar spine as well as the psoas insufficiency syndrome. It was revealed that inappropriately fitting footwear lead to various foot conditions and abnormal lower kinetic chain biomechanics. Environmental factors, such as the dance surface, also have implications in ballet injury. The author concluded that ballet injuries have a multifactorial etiology that primarily involves the interplay of compensatory biomechanics in the spine and lower extremity, environmental factors, and footwear. In addition, some clinical recommendations have been made regarding the physical therapy management of ballet injuries.

Ballet injuries. An analysis of epidemiology and financial outcome

The financial outcome and epidemiology of ballet dancers' injuries were studied by examining workers' compensation insurance records covering 3 seasons (3 years) of activity for a large professional ballet company. One hundred four dancers sustained 309 injuries that resulted in insurance payouts for medical costs of $398,396. The average cost per injury was $1289. Although only 4.2% of the injuries resulted in medical costs exceeding $5000, these represented 60.0% of the total medical costs. Nine injuries resulted in medical costs in excess of $10,000 each. Overall, there were 2.97 injuries per injured dancer. Twenty-four dancers (23.0% of the injured) sustained 5 or more injuries each and thus were responsible for 51.9% (161) of all injuries. The foot (74 injuries, 23.9%), lumbar spine (71, 23.0%), and ankle (41, 13.3%) were the most frequently injured anatomic regions. The experience of this ballet company is similar to that of a college athletic department or a professional sports team. All could employ similar strategies to reduce injuries and associated costs.

Gymnastic injuries

In the past 15 to 20 years gymnastics has become very popular. The increased participation exposes a greater number of athletes to potential injury. The risk of gymnastic injuries seems to be proportional to the level of the athletes; the higher the level of gymnastics, the more hours are spent in practice, with a greater exposure time. With the increased risk in gymnastics, the incidence of acute injuries will also increase, and as the skill level increases, the load during the workout will also increase, providing more opportunity for chronic injuries. As in many sports, the ankle is the most injured body part. Some injuries, however, seem to be specific to gymnastics. In gymnastics the upper extremities are used as weightbearing limbs, so high impact loads are distributed through the elbow and wrist joint. Back problems appear to result not only from single episodes of macrotrauma, but also from repeated microtrauma caused by specific impact loads during vaults and hyperextension. Early detection is the key to treating elbow, wrist and back pain in the gymnast. Reinjury following an acute injury may be reduced by allowing for complete rehabilitation before returning to full practice. Some studies indicate that maturation rate could play a potential role in injury predisposition. The combination of periods of rapid growth and intense training could provide for conditions where the gymnast is more injury prone.

Relationship of turnout to hip abduction in professional ballet dancers

The ability to externally rotate or turn out the hip is fundamental to ballet. Every classical dancer aims to achieve perfect turnout. The purpose of this study was to determine how much turnout is necessary for maximal abduction. It was hypothesized that moderate turnout is sufficient for this purpose. Twenty-two professional dancers from the Alberta Ballet Company were studied. Measurements of passive hip abduction were taken at 0 degree, 45 degrees, 60 degrees, 70 degrees, 80 degrees, 90 degrees and maximum hip lateral rotation using a goniometer and Leighton flexometer. Statistical analysis was done using Pearson correlation coefficients. A significant positive correlation was found between abduction and lateral rotation (P less than 0.05). The greater the position of external rotation, the more abduction achieved. In conclusion, the traditional emphasis on good turnout has some scientific merit and functional implications.