External rotation of the leg with both feet positioned at 90 degrees laterally from parallel (i.e., both feet aligned within the frontal plane, thus creating a 180-degree angle) is considered “perfect” turnout (see Fig. 8-1, A). Although turnout should ideally come primarily from the hip, most of the dancer’s functional turnout is accomplished by rotational components at the hip, knee, foot, and ankle joints. If hip external rotation is not sufficient, the dancer will compensate by forcing turnout by using compensatory strategies in weight bearing such as excessive pronation, foot abduction, knee flexion, external rotation torsion at the knees, and increased lumbar lordosis (Fig. 8-2). Compensated turnout is associated with nontraumatic musculoskeletal injuries in dancers, including anterior hip pain secondary to tendinopathy or FAI.18–20
Several factors or anatomic variations can contribute to, or limit, the amount of turnout achieved at the hip joint: angle of femoral version, orientation of the acetabulum, shape of the femoral neck, and elasticity of the iliofemoral ligament, as well as flexibility and strength balance of the musculature surrounding the hip joint. Individual differences in bony anatomy and structural alignment of the hip can also leave some dancers more susceptible to hip injury.
Femoral version refers to the angular measurement of the axis of the femoral neck in relation to the femoral condyles at the distal femur (Fig. 8-3). The femoral head is normally angled anteriorly in relation to the transcondylar axis, and this is referred to as femoral anteversion. At birth, femoral version measures approximately 35 to 40 degrees of anteversion, and by skeletal maturation, it measures on average between 8 and 15 degrees21–23 of anteversion, which is considered normal range. At skeletal maturity, however, some variations in femoral version angles occur; some persons have up to 30 degrees of anteversion, whereas others have 10 to 15 degrees of femoral retroversion.21 Femoral retroversion refers to a posterior position of the femoral head in relation to the transcondylar axis.
The amount of femoral version can greatly influence the amount of turnout a dancer can achieve at the hip (Fig. 8-4). One study found that average femoral neck anteversion in dancers (11.9 degrees) was similar to that in the average population.23 Excessive femoral anteversion, however, results in internal rotation of the femur to position the head of the femur in the acetabulum, and it can lead to “in-toeing” (see Fig. 8-4, C). Increased femoral anteversion is associated with restricted hip external rotation, attributed to early contact of the neck of the femur with the lateral edge of the acetabulum.24 Femoral anteversion affects alignment throughout the lower extremity and results in increased lumbar lordosis, an increased Q angle, patella-femoral disorders, and excessive pronation of the feet.25 An excessively anteverted position of the femur is not desirable for the dancer because it significantly limits the dancer’s ability to assume positions, maintain lower extremity and trunk alignment, and achieve the level of flexibility needed for many forms of dance. Conversely, femoral retroversion can lead to ‘out-toeing,’ which is desirable for the dancer (see Fig. 8-4, B). Retroversion is associated with increased external rotation range of motion, and it allows a dancer to achieve greater turnout of the lower extremities with fewer compensatory strategies in the pelvis, knee, and foot.
Femoral version is typically established by 11 to 12 years of age as a result of bony maturity and cannot be influenced through training.7 However, evidence indicates that dance training for 6 or more hours a week between the ages of 11 and 14 years can enable dancers to achieve greater turnout with fewer compensatory strategies by eliciting adaptive osseous changes and reducing femoral torsion.26
Anatomic deviations of the femoral neck or acetabulum may negatively influence hip joint articulation and available range of motion, and they may predispose a dancer to injury. The acetabulum is cup shaped, providing a deep socket for the head of the femur (Fig. 8-5). Orientation, or depth and shape, of the acetabulum can affect the extent of turnout possible for a dancer. An acetabulum that is shallow (e.g., in hip dysplasia) and laterally oriented increases the external rotation range of motion available at the hip because contact between the femur and the acetabulum occur at a later point in the motion. Conversely, an acetabulum that is unusually deep and anteriorly oriented limits the amount of external rotation available as a result of earlier contact of joint surfaces (i.e., the femur contacts the edge of the acetabulum sooner during the motion).24 Chapters 1 and 4 contain additional discussion of the anatomy and orientation of the acetabulum, the effects on lower extremity alignment and range of motion, and associated risk of injuries.
The shape and length of the femoral neck can also affect the extent of turnout achieved by a dancer. A longer femoral neck with a more concave shape allows greater amounts of abduction and external rotation at the hip, whereas a less concave and shorter femoral neck limits the end ranges of motion as a result of femoral acetabular abutment.24 Continued and repeated abutment may lead to FAI, discussed later in this chapter, as well as in Chapter 4.
The surrounding musculature, joint capsule, and associated ligamentous structures of the hip can also greatly affect available turnout for the dancer. A detailed discussion of structure and function of ligaments of the hip is provided later in this chapter, as well as in Chapter 1. The joint capsule and, in particular, the iliofemoral ligament become taut at the end ranges of external rotation. As such, extensibility of these structures can improve a dancer’s turnout. Similarly, tight musculature, particularly those with antagonist actions on external rotation, can also limit potential for turnout. Finally, strength of the external rotators of the hip, particularly at the end ranges, can help a dancer achieve his or her available turnout potential. Specific exercises designed to increase end-range strength and flexibility to improve turnout are presented later in this chapter.
Thorough evaluation of the dancer should include assessment of hip external rotation range of motion and limiting factors, functional turnout, and contribution of compensatory strategies to achieve turnout. Evidence supports proper and accurate assessment of turnout and compensatory factors in dancers to predict or prevent injury,25 as well as to determine the amount of turnout available, or turnout capacity.27 An association exists between reduced and compensated turnout and lower extremity injuries in dancers.18,23,28 Dancers who demonstrate excessive use of compensatory strategies to compensate for insufficient hip external rotation to achieve maximal desired turnout may be at greater risk of injury.28,29
Clinical assessment of turnout in dancers is an important component of evaluation and treatment of hip injury in this population. A critical review of the literature provides various methods of measuring turnout, and components of turnout, in dancers (e.g., passive versus active, weight bearing versus non–weight bearing, hip in extension versus flexion). Some of these methods are further discussed and presented in this section.
Previous studies indicated hip external rotation range-of-motion average values in dancers of 40 to 50 degrees passively30 and at 30 to 40 degrees actively.18,31,32 Up to 60 degrees of functional turnout (i.e., turnout during dance positions and movements) occurs exclusively through hip external rotation range of motion, with the rest contributed by the lower leg, thus achieving 69 to 87 degrees of functional turnout through compensatory strategies.18,29,33 This potential for using compensatory strategies to forcefully achieve desired turnout may increase a dancer’s susceptibility to musculoskeletal injury not only of the hip, but also of other joints of the lower extremity.20
Findings of a study by Negus and associates18 underscore the importance of assessing turnout as a potential contributor to overuse injuries in ballet dancers. The study examined relationships between components of turnout and injury history in 29 ballet dancers, as well as the clinical utility of 3 turnout assessment methods (active and passive external rotation in supine and standing functional turnout). Results indicated a significant difference between static and dynamic turnout control. The researchers concluded that functional measures of turnout are more relevant to the prevalence of nontraumatic injuries, and therefore measurement of hip external rotation range of motion alone is insufficient.18 Other studies supported clinical assessment of turnout in standing, incorporating the entire lower extremity in the turnout measurement.27,30,34 Assessment of functional turnout, also referred to as total turnout, is useful for clinicians, as well as dance teachers, to identify potential limitations in turnout, risk for injury as a result of compensation, and turnout capacity.24,27,31,34 Three recommended methods to assess functional (total) turnout include passive supine turnout, standing static turnout, and standing dynamic turnout.
Passive supine turnout, as described by Grossman and associates,34 is measured with a goniometer with the dancer lying in the supine position with the knees and hips extended. The examiner passively dorsiflexes the foot while attempting to control hindfoot and forefoot alignment (to prevent pronation and foot abduction) because these factors can contribute to turnout. The dancer is cued to limit pelvic rotation by keeping the pelvis flat on the examining table and to maintain knee extension. The moving arm of the goniometer is placed along the second metatarsal, and the stationary arm is maintained in a vertical position, perpendicular to the table. The examiner passively rotates the lower extremity until motion is restricted by a capsular end feel (Fig. 8-6).
Standing static turnout is measured with the dancer standing on a whiteboard or white paper. The dancer is asked to position himself or herself actively in turnout, and the angle is measured with a goniometer directly under the foot, or by using tracings.27,34 The stationary arm is aligned with the sagittal plane, and the moving arm is aligned with the second metatarsal (Fig. 8-7). Dancers can use friction of the floor to gain turnout in standing, and this may increase total turnout.18
Dynamic standing turnout is considered more functional, and therefore is more relevant than hip external rotation range of motion to prevalence of nontraumatic dance injuries.18 This method is performed actively, and friction is eliminated by using rotational disks. The dancer stands on the rotational disks with the medial and lateral malleoli placed along the central diameter of each disk. The second metatarsal is marked, and a measurement of the turnout angle is taken at the greatest range of active turnout by using markings on the surface, or a digital photograph (Fig. 8-8). Some research indicates that active turnout measurements may be significantly lower than passive total turnout measurements, and this information may be particularly important when treating a dancer for injuries most likely caused by compensatory strategies.18,27,34
Although functional turnout is clinically useful, it is important to address all contributing factors of turnout in the evaluation and treatment of the dancer’s hip. Several components for clinical evaluation of the turnout are recommended: hip external rotation range of motion, passive functional turnout, standing static functional turnout, standing active functional turnout, and femoral anteversion.
To determine the hip’s external rotation contribution to turnout, the clinician should use basic goniometric measurement techniques described in the orthopedic literature and the dance medicine literature.35–37 Standard goniometric measurement of active and passive hip external rotation should be performed with the hip in flexion (sitting) or extension (prone). Each position provides the clinician with valuable information because turnout during dance is performed in a variety of hip positions, with both a closed chain and an open chain (see also Chapter 2 for hip external rotation range of motion assessment).
For prone goniometric measurement, position the dancer prone with both legs extended at shoulder width apart. The pelvis may be stabilized with a belt to keep the anterior-superior iliac spine on the surface of the table. Maintain the testing leg in 90 degrees of knee flexion. Passively externally rotate the testing leg to the end range, with care taken to limit compensatory pelvic tilt or knee motion. Place the axis of the goniometer on the patella tendon, with the stationary arm perpendicular to the floor, and the moving arm along the tibia (Fig. 8-9, A).
For sitting goniometric measurement, position the dancer sitting with knees and hips flexed at 90 degrees, and allow the lower legs to hang over the edge of the table. The pelvis may be stabilized with a belt to keep weight evenly distributed on both sides. Passively externally rotate the testing leg to the end range, taking care to limit compensatory pelvic tilt or knee motion. Place the axis of the goniometer on the patella tendon, the stationary arm perpendicular to the floor, and the moving arm along the tibia (Fig. 8-9, B).
Clinical assessment of femoral anteversion also provides valuable information about structural limitations to turnout, as well as the potential for sustaining injury secondary to compensatory strategies to achieve greater turnout. A technique for clinical assessment, Craig test, correlates closely (within 4 degrees) with intraoperative measurement values.38 With the patient prone with the knee flexed at 90 degrees, the examiner palpates the greater trochanter while internally rotating the hip. At the point of maximum trochanteric prominence (i.e., when the neck of femur is parallel to the floor), the angle between the tibia midshaft and true vertical is measured with a goniometer (Fig. 8-10). This measurement represents femoral anteversion.38 As stated earlier, normal range in the general population is 8 to 15 degrees. In the dance population, the lower the amount of femoral anteversion, the greater is the potential for achieving desirable turnout. Conversely, the greater the amount of femoral anteversion, the more limited the dancer will be in achieving desirable turnout, regardless of flexibility and strength of the hip.
Styles of Dance
In recent years, dance has become more diverse, with many different styles and contemporary interpretations of traditional types of dance. Additionally, new and ethnic forms of dance have gained popularity in the mainstream dance circuit. In addition to ballet, jazz, and tap, it is not uncommon to locate community dance studios that offer classes in modern dance, Irish dance, Scottish highland dance, hip hop, capoeira, acro, salsa, flamenco, jumpstyle, belly dance, and more. Each dance genre requires specific and stylistic movements that may increase risk for injuries to the hip.9,39–41
Excessive turnout is emphasized in some forms of dance, including ballet and Irish dance. In Irish dance, for example, excessive turnout and overcrossed legs are emphasized. In this form of dance, powerful jumps and stylistic maneuvers begin and end with the lower extremities externally rotated and adducted, which can lead to strength and flexibility imbalances that predispose the dancer to hip and other lower extremity injuries, some of which are discussed later in this chapter (Fig. 8-11).
Some forms of dance, however, do not emphasize extreme turnout, and the dancer will feel less pressure to achieve the excessive turnout position. These dance styles include jazz, modern, and tap. Evidence supports that these dancers achieve a lower mean turnout position than do ballet dancers.42
Early Excessive Training in Young Dancers
Not unlike in other athletic or performing arts populations, long hours of practice and the sometimes competitive or compulsive nature of the athlete may lead him or her to ignore early warning signs of injury. The dancing culture embodies this mentality, with a perception that injuries in dance are inevitable, and that dancing requires a stoic attitude toward pain, thus leading most dancers to “work through the pain.”43–45 Many dancers fear that physicians or other health providers will advise them to stop dancing,46 or they believe that health practitioners do not understand dance technique and lack training in dance injuries.47 Evidence suggests that dancers may not comply with treatment protocols over the long term “if they perceive that such compliance would interfere with their training or performance.”48 Nonetheless, studies are encouraging, with findings indicating that physical therapists are viewed more favorably than other health providers by dancers and are seen as providing high-quality information during therapy.48 The literature underscores the importance of being a therapist who is knowledgeable about general dance technique, specific dance style, training regimens, and dance injuries to establish an effective rapport and improved outcomes when working with this population.50,51
Muscle fatigue from overtraining can also lead to injury.45 Previous studies indicated that more dance-related injuries are caused by overuse, rather than a defined traumatic injury.3–5,9,15,16,52 Additionally, a sudden increase in training without the necessary increases in muscle strength and muscle endurance can precede the development of injuries, including stress fractures.53 This finding underscores the need for proper training to minimize compensatory strategies, emphasis on correct technique, and education of both dancers and teachers on the importance of early identification and treatment of overuse injuries. Additional evidence suggests that periods of rest may be important in the prevention of injuries related to fatigue or overtraining. Previous research findings revealed that 90% of dancers felt tired when their injuries occurred, and 67% reported sustaining injuries toward the end of the season (performance or competition).54 Another study found that fitness levels were lower at the end of the dancer’s season, and they improved after the summer off-season.55 This finding strengthens the argument for periodization or rest periods for recovery. In some competitive or performance dance troops, however, no rest seasons exist, and training is year round. This is an important point of education for dancers, teachers, and directors in the prevention of dance injuries.
Joint Hypermobility and Stability
Epidemiologic studies suggest that the rate of hypermobility among dancers can be as high as 44%, particularly in students.56 General joint hypermobility does not appear to be a factor that contributes to injury in dancers.33,57 Rather, it is the lack of specific ranges of mobility, or core and stabilizing strength and control surrounding hypermobile joints, that may predispose dancers to injury.
Evidence indicates that joint hypermobility syndrome, a genetically inherited disorder of the connective tissue, has been correlated with increased injury in dancers.57 The clinical presentation of this disorder consists of local or widespread musculoskeletal symptoms and joint hypermobility. Dancers with hypermobility and musculoskeletal symptoms can be screened to determine the presence of joint hypermobility syndrome or general joint hypermobility by using the Beighton scoring and Brighton criteria.57 Although neither method was specifically designed for use in the dance population, and some criticisms of their applicability and validity in dancers and across various styles of dance have been expressed,58 these measures are widely used clinically and in research. The Beighton scoring system of 1973,59 a nine-point test consisting of active and passive movements, is a reliable indicator of general joint hypermobility60 ( Fig. 8-12 and Table 8-2). A score of 4 or more suggests general joint hyperlaxity throughout the body. The Brighton criteria provide a measure of joint hypermobility syndrome based on validated criteria.61 These criteria include the Beighton test score, symptoms, and signs of connective tissue deficiency61 (Table 8-3).
Beighton Scoring System
|Passive extension of the fifth finger beyond 90 degrees||1 point each side|
|Passive flexion of the thumb to touch the forearm||1 point each side|
|Hyperextension of the elbows beyond 10 degrees||1 point each side|
|Hyperextension of the knees beyond 10 degrees||1 point each side|
|Forward flexion of the trunk in standing with knees fully extended and palms of the hands flat on the floor||1 point|
|Major Criteria||Minor Criteria|
|A Beighton score of 4 or greater|
Arthralgia for >3 months in 4 or more joints
|A Beighton score of 1, 2, or 3|
Arthralgia (>3 months’ duration) in 1-3 joints or back pain (>3 months’ duration) or spondylosis, spondylolysis, spondylolisthesis
Dislocation or subluxation in >1 joint or in 1 joint on >1 occasion
>3 soft tissue lesions (e.g., epicondylitis, bursitis)
Skin striae, hyperextensibility, thin skin, abnormal scarring
Ocular signs (e.g., drooping eyelids, myopia)
Varicose veins, hernia, or uterine or rectal prolapse
Mitral valve prolapse
|Requirements for diagnosis (presence of any 1 of the following conditions):|
For dancers with joint hypermobility syndrome, education and conditioning to improve neuromuscular control are crucial to preventing dance-related injury.62,63 Hypermobility-related injury is discussed later in this chapter.
Nutrition and Female Athlete Triad
Poor nutrition and its impact on bone health in dancers have been topics of discussion and research for decades. Most forms of dance emphasize aesthetics of body movement and shape. This focus can lead to a preoccupation with body image and an increased risk for developing an eating disorder.64 Stress fractures are associated with a more restrictive diet.65 In a study published in 1990, Frusztajer and colleagues65 found that dancers demonstrated energy restriction accompanied by decreased protein and fat intake, as well as deficient intake of minerals and vitamins that are crucial to optimal bone health; 70% of the dancers studied consumed less than 85% of the recommended dietary allowances for calories, and 60% presented with deficient protein intake. In 2000, Merrilees and associates66 studied the effects of dairy food supplements on bone mineral density (BMD) in girls 15 to 18 years old. Results of this study indicated that daily supplemental calcium significantly improved BMD at the trochanter, femoral neck, and lumbar spine.
Deficiencies in nutrients, particularly bone-building nutrients such as calcium, magnesium, iron, and vitamins D, K, and C may limit new bone formation.67 Sustained energy deficit, inadequate caloric intake relative to energy expenditure through exercise, can disrupt hormone balance. This disruption, in turn, can lead to decreased osteoblast activity, increased bone resorption, and reduced ability to repair microdamage.68–71 Nutritional deficits compromise bone by increasing susceptibility to fractures.31 Lack of adequate nutrition can also affect muscular strength.72
The female athlete triad (FAT) is a syndrome of three interrelated disorders: energy deficits (disordered eating), menstrual irregularities, and decreased bone density (Fig. 8-13). Energy availability is the cornerstone of FAT.11 All three disorders of FAT are associated with inadequate energy reserves.73 Female athletes with disordered eating are more than twice as likely to have menstrual irregularities than female athletes without disordered eating.74 Athletes with menstrual irregularity have significantly lower BMD.75
Female athletes, particularly those involved in a sport with an aesthetic component (e.g., dance, figure skating, gymnastics), are at greater risk for developing FAT.11 In a study comparing elite professional female dancers and recreationally active female nondancers, the dancers experienced delayed menarche, decreased energy intake, and abnormal eating behaviors, exhibiting symptoms of the three conditions of FAT.76 As mentioned previously, lack of nutrition from disordered eating can contribute to poor bone health and result in increased risk for stress fracture.17 A relationship exists between components of FAT and stress fracture in dancers.77,78 Additionally, a positive correlation is seen specifically between menstrual dysfunction and stress fractures.79 Barrack and associates80 studied the effect of single or combined risk factors (defined by FAT) with bone stress injuries in 259 female adolescents and young women. FAT risk factors included low body weight, low body mass index, high-volume exercise (>12 hours/week of purposeful exercise), elevated dietary restraint, pathogenic weight control behavior, participation in a leanness sport, late age of menarche, oligomenorrhea or amenorrhea, and low BMD. Findings indicate that cumulative risk for bone stress injury increases as the number of FAT-related risk factors accumulates.
The effects of nutrition, dance exposure, and pubertal delay on BMD were examined in 127 female preprofessional ballet dancers, 15 to 17 years old,81 and the findings supported the importance of a balanced diet including calcium from dairy sources as a positive determinant for bone development. The number of years since menarche was also positively correlated with bone development.81 In this study, the weight-bearing activity of dance appeared to protect BMD in weight-bearing bones. Similarly, in a controlled study, Friesen and colleagues82 examined body composition, BMD, eating behaviors, and menstrual dysfunction in 31 collegiate modern dancers who were 18 to 25 years old. Compared with controls, the dancers reported a higher prevalence of disordered eating and menstrual dysfunction. Bone mass in the dancers was higher for weight-bearing bones, attributed to the weight-bearing aspects of modern dance training.82 However, evidence indicates that although the weight-bearing aspects of dance appear to increase BMD of the lumbar spine and femoral neck, amenorrheic dancers have significantly lower BMD at the femoral neck and spine compared with their eumenorrheic counterparts.81,83 This decreased BMD puts amenorrheic dancers at risk for fracture. Dancers have a higher incidence of bone stress injuries to the lower extremities, including the femur, acetabulum, and sacrum.8,78,84,85
Disordered eating, menstrual irregularities, and low BMD are important health issues for all dancers regardless of skill level.86 Despite the evidence to support the importance of proper nutrition and energy intake for dancers, most dance programs do not initiate nutrition education with young dancers and their parents. Yet, the aesthetics and desirable thin physique of dancers is continuously reinforced in the culture of dance. Proper nutrition and eating habits should be developed alongside dance technique, particularly for young and adolescent dancers, to prevent the development of FAT and its associated risk for bone stress injuries.
Snapping Hip Syndrome (Coxa Saltans)
Snapping hip, or coxa saltans, manifests as an audible or palpable extraarticular snapping that occurs around the hip during movement. Although often painless, it may be associated with pain or discomfort. Snapping hip occurs in approximately 10% of the general population, but it is especially prevalent in athletes, including dancers.87 Many variables are associated with the onset of snapping hip, including muscle imbalance, muscle fatigue, muscular weakness, inadequate warmup, suboptimal training, age, and previous injury to the same muscle tissue.33,88
Snapping hip is particularly common in dancers, and it accounts for approximately 43.8% of hip problems in ballet dancers.89 To diagnose and treat snapping hip properly, it is important to identify the cause. The causes of extraarticular snapping hip can be divided into two categories: external snapping hip syndrome (ESHS) and internal snapping hip syndrome (ISHS). These disorders are discussed in the context of dance-related causes and rehabilitation. For more detailed information about snapping hip syndrome, please see Chapter 3.
External Snapping Hip Syndrome
External snapping is attributed to the iliotibial band (ITB) or gluteus maximus snapping over the greater trochanter. Dancers with ESHS often describe a snapping sound from their lateral hip that occurs during movement transitions. This snap, or clunk sound, typically occurs when returning the leg from an extended, abducted, and externally rotated alignment.90
The onset of ESHS occurs between 14 and 16 years of age for approximately 50% of dancers, and it coincides with the age when a dancer develops the strength and flexibility to achieve and maintain their extensions at or above 90 degrees.91 It is associated with adaptive shortening of the hip abductors and external rotators, which may result from an increase in the intensity and frequency of dance training, and it may be perpetuated by faulty dance technique as the dancer is developing new skills.91 Factors that increase the risk of external snapping hip include a wide pelvis, prominent greater trochanter, ligamentous hyperlaxity, weakness of the hip abductors, and tightness of the ITB.92,93
Internal Snapping Hip Syndrome
In ISHS, the iliopsoas tendon snaps over a bony prominence, typically the iliopectineal eminence, femoral head, anterior capsule, or lesser trochanter. The tendon is susceptible to injury when the hip is flexed, abducted, and externally rotated. In dance, several positions require this motion repetitively. For example, in ballet, dancers access this motion when they move into développé to passé or développé in second positions (Fig. 8-14). These positions have been theorized to cause the psoas tendon to pull into a “U” shape as it passes below the inguinal ligament.94
The majority of research on snapping hip syndrome in dancers has focused specifically on ballet dancers. Currently, no studies have specifically investigated snapping hip syndrome in other types or styles of dance. This gap in research may reflect the ability to study large subject populations in ballet schools and professional ballet academies.
The dancer’s symptoms greatly assist in the diagnosis of snapping hip syndrome. In a study of ballet dancers, Winslow and Yoder found that 90% reported a history of experiencing a hip that “cracks, pops, snaps, or clicks,” with 16.7% of symptoms specifically occurring at the lateral hip.91 In the majority of cases, however, the dancers were unable to localize the source of the noise. Some degree of pain was reported with the snap at the greater trochanter by 58.4% of those dancers, and 59% could voluntarily reproduce the snap.91
It may be valuable to have the dancer demonstrate the motions that provoke the snapping to differentiate the source of the snapping. Provocation tests applied by the clinician to produce a palpable snap are not necessary when voluntary snapping is present. In the presence of voluntary snapping, the snapping is palpable to the clinician. The specific dance movements that commonly cause the snap involve the dancer in the second position, with the leg approaching or passing 90 degrees of abduction in the turned-out position (Fig. 8-15). This movement has been implicated in iliopsoas snapping.95 Two other movements have been linked to ITB snapping: the front kick (grand battement) and a forward bend (Fig. 8-16).95 A small number of dancers found that by snapping the hip on purpose, they could obtain pain relief.92
Dancers are known for their high degree of flexibility, but repetition of specific motions (e.g., to achieve desired turnout) can lead to imbalances in flexibility and compensatory soft tissue tightness. A tight tensor fasciae latae (TFL) and ITB, specifically, may contribute to snapping hip, and they should be evaluated. ITB flexibility can be assessed in the Ober position (Fig. 8-17, A). Psoas flexibility measured in the Thomas position (Fig. 8-17, B) can often reveal iliopsoas restriction, as well as compensatory tightness in the TFL. TFL tightness is indicated if the test leg remains in external rotation or abducts at the full hip extension position (Fig. 8-17, C). The iliopsoas is a deep structure, and isolating the tendon by manual palpation is difficult. Chapter 2 has further details on these test positions.
Assessment of strength in the muscles surrounding the hip is also important. A study by Bennell and colleagues31 found that dancers generally have less hip muscle strength in their flexors and abductors than do their athlete or nonathlete counterparts. Additionally, dancers in the study ranked in the lower 77th strength percentile when compared with other female athletes that included soccer players, weight lifters, and runners. This relative strength deficiency may be a contributing factor to the high incidence of snapping hip in the dance population.31
Rehabilitation and Treatment Considerations
Snapping hip may not be problematic for all dancers, but it may cause a varying degree of pain or discomfort at some point during their dance career. Rehabilitation of snapping hip dysfunction of either the ISHS or the ESHS must consider the following key issues: