Measuring Dancer's Active and Passive Turnout - Ingenta Connect

Original Article

Measuring Dancer’s Active and Passive Turnout Gayanne Grossman, Ed.M., P.T.

Abstract Degree of overall turnout in the lower extremity involves not only hip external rotation but contributions from the knee, tibia, foot, and ankle as well. There are valid and reliable methods to measure isolated joint passive range of motion (PROM) within the field of orthopaedics. Specialized approaches to measuring turnout in a manner useful to dancers have begun to appear in the literature. This article will discuss these methods and a strategy for combining them to provide useful information for clinicians and dancers.

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f one had to think of a specialized skill, unique to dance, it would be turnout. No other art form or sport uses the externally rotated leg as a basis for as many movements. There are extensive reports within the dance medicine literature that poor turnout control or forced turnout may result in maladaptive postures, potential bony changes, injuries, degenerative disorders, and decreased strength. 1-4 Externally rotating the lower extremity beyond its biomechanical or strength capabilities may generate compensations, such as anterior pelvic tilt with concurrent

lumbar hyperextension and excessive pronation.4-6 Bony changes such as bunions, increased external tibial torsion, or femoral neck adaptations may result.7,8 Incorrect use of turnout may result in injuries to the supportive structures in the weightbearing chain. 9-11 Mal-alignments associated with poor turnout control can affect the muscles’ ability to produce force by altering the lengthtension relationship.4 At present, studies documenting range of motion (ROM) norms for dancers and reliable methods for measuring hip external rotation exist.1,2,12-17 However, a systematic protocol for a single measurement that includes all passive contributions to turnout (hip, knee, tibia, foot, and ankle) has yet to be established. Total passive turnout measurement may assist dancers by providing information critical to the creation of effective training regimens and may assist with the design of injury prevention programs. The information gathered through a systematic measurement protocol will facilitate growth of the global dance medicine database. Further, there may not be inter-tester re-

Gayanne Grossman, Ed.M., P.T., is the physical therapist for Temple University’s Dance Medicine Clinic, Muhlenberg College Department of Theatre and Dance. She also teaches dance kinesiology as an affiliate faculty member in the Department of Dance at Temple University and Muhlenberg College. Correspondence: Gayanne Grossman, Ed.M., P.T., Temple University, 309 Vivacqua Hall, 1700 North Broad Street, Philadelphia, Pennsylvania 19122.

liability without systematic measurement techniques. A review of existing measurement methods, suggestions for active and passive turnout measurement methods, and an approach for comparing active and passive turnout values will be offered.

History Volumes of research in dance medicine and science began to accumulate in the 1970s. Early research in dance medicine and science generated descriptive material including articles describing turnout.10,18 These articles describe the biomechanical nature of turnout and its relationship to the weight-bearing chain. Some include discussion of the percent of additional turnout contributed from the knee and foot.10,18 Research was conducted to establish ROM norms for dancers.6,16,17,19 Discussions ensued about the causal relationship between poor turnout control, other physical limitations, and injuries.1,3,5,6,10,16 The late 1990s saw a rise in the popularity of dance screenings. In 1997, an entire issue of this journal20 was dedicated to the topic. Methods to measure turnout were included and a suggestion was made to standardize testing methods, including ROM.21

Biomechanical Basis and Background To understand the nature of all joints contributing to turnout of the dancer’s leg and initiate a dialogue regarding a 49

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new method of measurement, a review of biomechanics and existing measurement protocols is required. The Hip Joint The hip is a ball and socket joint; the stability is fashioned by the acetabular shape and deepened by the fibrocartilaginous labrum. Additional support is provided by the ilio-femoral (Y ligament), pubo-femoral, and ischio-femoral ligaments.23 The Y ligament is of particular importance to dancers because of its role limiting hip extension and external rotation.4,24 A shortened hip joint capsule or muscles will also limit hip extension and/or external rotation. 4,10 However, the primary limitation of hip external rotation is the degree of femoral anteversion; the angle created between the long axis of the femoral neck and the transcondylar axis of the distal femur.3 Normal anteversion (approximately 15° in adults)15,25 or retroversion are desirable conditions for dancers whose idiom requires turnout.16,18 Excessive anteversion may result in intoeing and is often problematic for the dancer because the femoral neck abuts the posterior acetabular ridge during hip external rotation limiting motion.24 Some suggest excessive anteversion may exist when internal rotation exceeds external rotation.15,18,26 The shape of the femoral neck also affects external rotation. A longer and more concave neck is less likely to have contact with the acetabulum during external rotation than a neck that is shorter and less concave.24 The Knee Joint The extended knee naturally and safely contributes a few degrees to the total turnout measurement. The knee joint is a modified hinge joint. Its primary actions are flexion and extension. However, during terminal extension (the last 20° of knee extension), the tibia externally rotates approximately 10° on the femur to lock the knee to stand on a stable leg.23,27 This action, known as the screw-home mechanism, is caused by the shape of the bones and the configuration of the ligaments.

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In full knee extension, the knee locks and achieves maximal stability as the ligaments are taut and bony congruency is maximized.15,27,28 The tibia unlocks during the first few degrees of knee flexion by internally rotating on the femur.27,28 At mid-range flexion there is less tension on the ligaments and the bony surfaces are incongruent, therefore femoral-tibial alignment (rotation) is less restricted.15,27,28 The tibia can be forced (by friction from the floor) to externally rotate on the femur in flexed positions such as in plié (mini squats).10 Dancers may take advantage of ligamentous laxity during knee flexion and force tibial external rotation thus creating the illusion of additional turnout. Excessive tibial external rotation achieved by using friction from the floor may be unsafe for the knee joint because excessive rotation may stretch the ligaments, damage the menisci, mal-align the patella, and place excessive compression on the articular cartilage.29 The Tibia Tibial torsion is twisting of the shaft on its long axis. Normal external tibial torsion is 10° to 18°.15 External tibial torsion will contribute a few degrees to overall turnout in the lower extremity. Greater than 20° of torsion is considered excessive and may result in patellofemoral tracking problems.6 An additional, but less frequent, consideration is also internal tibial torsion. Greater than 10° of internal tibial torsion is excessive and may result in intoeing.6 This bony configuration may be less conducive to dance forms requiring turnout. The Foot and Ankle Complex The talocrural (ankle) joint is a hinge joint. Dorsiflexion and plantar flexion are the primary motions. Dorsiflexion occurs on an oblique axis because the tip of the lateral malleolus is distal to the tip of the medial malleolus. The axis of motion lies on the horizontal plane distal to the tips of both malleoli from slightly proximal and anteromedial to slightly distal and posterolateral.30-32 This contributes up

to 6° of out-toeing during dorsiflexion.33 These few degrees of out-toeing may contribute to the total turnout measurement. The subtalar joint contributes to the weight-bearing alignment of the lower extremity. The tibia follows the talus in weight-bearing situations.30,31 Supination (elevation of the medial longitudinal arch) or plantar flexion cause external tibial rotation. Pronation (depression of the medial longitudinal arch) or standing with the ankle dorsiflexed cause internal tibial rotation.23,31,32 Subtalar neutral (the absence of pronation or supination)34 is achieved when the angle between the bisection of the calcaneus and the distal third of the tibia is perpendicular.30 The metatarsal heads are in the same plane as the calcaneus in subtalar neutral.30

Current Practices For a comprehensive review of turnout it is important to describe the current practices for measuring isolated joint ROM, elaborate on an existing approach for measuring passive turnout, describe methods for measuring active or functional turnout, and compare active versus passive values. The turned out lower extremity includes not only ROM contributions from the hip but also the knee, tibia, foot, and ankle.4,6,9,10,17,35 Therefore, total lower extremity turnout is not achieved from pure hip external rotation. The knee joint, tibial torsion, ankle, and foot contribute approximately 13° to 30° to the total turnout.1,6,10 Hamilton suggests that in both men and women 58% of turnout comes from above the knee and 42% from below the knee.16 Methods for measuring isolated ROM at the hip, knee, foot, and ankle exist and are described in many orthopaedic publications.13-15 Some have suggested summing isolated joint ROM to discover the total passive turnout value for dancers.17,35,36 Khan and Bennell described a technique to ascertain total turnout by subtracting hip ROM from standing total active turnout (TAT) values to discover lower leg external rotation (turnout below the hip).35,36 Clippinger recommends a standing passive measurement that in-


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corporates all components of lower extremity turnout.37 To date, a single measurement technique for measuring passive lower extremity turnout that incorporates all contributions from the hip, knee, tibial torsion, and foot has not been documented. There is, however, documentation of active turnout testing for dancers that incorporates all passive contributions.1,17,35,36 Preliminary passive measurements should be taken with active measurements to help determine the available range for active motion. Measuring Isolated Passive Range of Motion Passive ROM implies the movement is produced by the examiner without muscular assistance from the subject.15,38 Total passive turnout (TPT) is the sum of the isolated passive ROM contributions from the hip, knee, tibial torsion, ankle, and foot. Methods to measure passive hip joint ROM, tibial torsion, and a single method to measure the combined contributions to TPT will be described. Measurement of isolated hip external rotation in dancers with the hip flexed or extended may have different values. Hip external rotation may vary with hip position.6,10,17,37,38 For example, ROM may increase in the flexed positions such as (front attitude) and abducted position (second) due to laxity of the Y ligament.2,23,37 Although, LiGreci-Mangini suggests that increased hip external rotation in dancers with the hip extended is due to anterior capsular stretching. 39 When seeking a baseline measurement for dancers, testers might avoid these ROM variations by choosing to measure prone with the hip extended and neutral abduction and adduction. This position is functional because it simulates the hip position of a dancer standing in first position and limits possible compensations from flexed or abducted hip positions. Both Gilbert and Clippinger suggest standing in first position with the knees extended as a functional baseline reflection of turnout.1,37 Compensations in the crossed positions are more difficult for teachers to monitor,1 therefore, mea-

Figure 1 Hip external rotation measured prone.

Figure 2 Tibial torsion measured prone with a flexed knee joint.

surements in crossed (third, fourth, and fifth), abducted (second position), or flexed (seated) positions may be taken for specific investigations but are not recommended for baseline assessments to limit possible outcome variations. Further, a baseline measurement in first position may help the tester to ascertain where turnout compensations occur. For a prone hip external rotation measurement, the tester stands at the

dancers feet, abducts the uninvolved extremity to 20°, flexes the knee of the extremity being measured to 90°, one arm of the goniometer is placed along the anterior border of the tibia and the other arm is on the sagittal plane perpendicular to the floor, then the extremity is passively externally rotated (Fig. 1).15, 21 Seated hip external rotation is measured with the hip and knee at 90° of flexion.13-15 The tester stands in front of the subject

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and places one arm of the goniometer along the anterior border of the tibia and the other perpendicular to the floor. Tibial torsion is important to measure because of its contribution to total lower extremity turnout. Tibial torsion can be determined by the angle drawn between the central tibial shaft at the tubercle to the center of the ankle motise.14 The tester extends the dancer’s legs with both patella facing forward and looks at the Fick angle, the foot relative to the anterior border of the tibia (normally 5° in infants and increases up to 18° in adults) to check for excessive out-toeing or in-toeing.15 Tibial torsion can also be measured prone (hip extended, knee flexed to 90°, and the ankle joint relaxed).18 One arm of the goniometer bisects the ankle joint (placed along the shaft of the second metatarsal) and the other arm is in line with the tibial tubercle (Fig. 2). Measuring Total Passive Turnout (TPT) As described in the biomechanics section and reported by dance medicine researchers and practitioners, the turned out lower extremity includes contributions from the hip, knee, tibia, foot, and ankle. A functional turnout measurement will need to include all these contributions. It is possible to individually measure and then sum all the contributions,17 but it may be more practical to take a single measurement in certain clinical situations. Clippinger suggested a TPT measurement technique with the dancer standing, anterior tilt monitored by the tester, and knee rotation controlled by the tester externally rotating the dancer’s thigh.37 The tester could then control the leg with the dancer’s foot. The approach can be simulated with the dancer supine and bony landmarks are easily accessible for goniometric measurement. In the supine position, standing in first position with knees extended is simulated and all bone and joint contributions of turnout are incorporated. With the dancer supine, the spine approximates neutral, the hip

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Figure 3 Total passive turnout measured supine.

joint is extended and externally rotated, the knee joint is externally rotated by the screw home mechanism, and out-toeing concurrent with dorsiflexion are incorporated into the measurement. Any contribution to total turnout from tibial torsion is included. The knee and ankle are closed packed limiting additional joint play. The pelvis is blocked from rotating by the table and the subject’s or another tester’s hands on both iliac crests. Pronation and forefoot abduction can be misleading to the tester (and the dancer) by adding additional degrees to TPT. The tester can maintain the subtalar neutral position by hand placement in an attempt to limit this compensation. To control subtalar neutral, the talar dome can be palpated to ensure symmetrical posterior glide in the ankle mortise during dorsiflexion. Then the tester’s thumb grasps the dancer’s medial calcaneus and, if possible, the navicular tuberosity while the testers fingers simultaneously control the lateral calcaneus. With this hand placement the tester can control foot position while controlling and externally rotating the subject’s lower extremity. One arm of the goniometer is placed along the shaft of the second metatarsal and the other arm on the midsagittal plane

perpendicular to the floor. The tester then externally rotates the subject’s leg until the capsular end-feel in the hip joint is perceived (Fig. 3). The dancer is cued verbally to place both hands on her iliac crests and keep the pelvis flat to the ceiling and not to allow the pelvis to rotate (a demonstration of pelvic rotation is performed by the tester) and to fully extend the knee. Then the dancer is told to relax her hip joint and let the tester do all the work. This technique is simple to perform and includes all passive turnout contributions. Evaluation of turnout should also include muscular contributions within available passive range. Measuring Total Active Turnout (TAT) Active ROM implies movement is produced within the passive ROM by active muscle contraction unassisted by the examiner.13,38 The amount of turnout the dancer can perform using all passive bone and joint contributions and muscular contraction is the total active turnout (TAT). Two measurements can be taken and compared. The first functional measurement is what the dancer actually uses standing in first position. The dancer is told to stand in her normal first position. The tester must check bony


Figure 4 Total active turnout measured standing.

landmarks to assure that the pelvis, spine, and feet are neutral and that the dancer does not attempt to over turnout by using friction from the floor. This measurement is taken with one arm of the goniometer along the shaft of the second metatarsal and the other arm lined up with the midsagittal plane. Alternatively, the dancer can stand on a flat goniometer (Fig. 4). Rotational disks such as Functional Footprints (Keller/West LLC) can be used for a second comparative measurement to determine how much TAT can be achieved using muscular force with most friction eliminated by the ball bearings (Fig. 5). Measurements of second through fifth positions while standing on the floor and on rotational disks can also be taken. Comparison between the active baseline measurement in first position and the other positions is useful. The tester may discover many discrepancies such as over rotation of the front foot in fifth position. TAT and TPT Differential Liederbach suggests that dancer evaluations should include a comparison between passive hip ROM and total active turnout (TAT) values standing in first position and on rotational disks.21 The tester should address these discrepancies and any others found between TPT and TAT. If the supine TPT measurement is different than the TAT measurement in standing first position or on the rotational disks, the discrepancy may indicate forced turnout, inability to use all available ROM, weakness or motor

Figure 5 Total active turnout measured on rotational disks.

control deficits, muscular tightness, or soft tissue restrictions. Some dancers force the lower extremity to turnout beyond its natural capabilities.3,4,11 This problem is common. Methods to decrease the amount of perceived structural resistance to hip external rotation or to increase the appearance of additional turnout include: anterior tilt with concurrent lumbar hyperextension (the Y ligament is less taut), external rotation of the knee in plié, and pronation of the foot.4 Though not as common, some dancers fail to use all their available ROM as revealed by the TPT measure, possibly due to strength or motor control deficits.4,37 It is also possible that soft tissue or joint restrictions are obstructing full ROM. There is evidence suggesting, for example, that sacroiliac joint dysfunction may restrict hip external rotation on the ipsilateral side.40 The dancer may be unaware of all potential ROM and may use less for various reasons including fear of injury. Some dancers may use variable degrees of turnout depending on the movement difficulty.

Implications Many of the movements in ballet, modern, and jazz dance depend upon the dancer having a secure turned-out

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lower extremity. Standard methods for measuring isolated components of turnout exist and are useful for scientists, clinicians, and dancers alike. Techniques for measuring total passive turnout have begun to appear in the literature. Refining and combining these measurement strategies could yield important benefits for dancers and those who treat them. There are many inherent difficulties in proposing an additional method of clinical evaluation. In this case, the proposed TPT evaluation is based on a review of techniques that have begun to appear in the literature, biomechanical theory, and an appreciation of dance positions. Dancers rely on their kinesthetic understanding of turnout for choosing standing turned out positions. Dancers use the amount of turnout that feels correct or looks good. The amount of turnout a dancer uses may differ from the actual amount when measured. The adoption of a valid and reliable series of turnout measurements may be beneficial for several reasons. It will encourage clinicians, including those unfamiliar with the treatment of dancers, to include turnout measurement in their evaluation. Motor re-patterning efforts can be directed toward the amount of turnout possible and include strengthening for all ranges of motion. This has the potential to decrease injuries related to poor turnout control and over turning out. Controversy exists about the possibility of effecting any change in the degree of anteversion.4,10,38 The dancer may not be able to increase turnout by any means including dance training. Fortunately for some dancers, anteversion naturally decreases with age. If enhancement beyond the normal reduction in anteversion is possible, it must occur before the plasticity of the bone decreases during puberty.3,4 After the bones become rigid any modest increase in external rotation is possible only by stretching the joint capsule and ligaments, although, the safety of this approach remains controversial. Though the average person has between 40° and

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50° of external rotation and professional ballet dancers may have up to 10 additional degrees,3,16 there is no evidence this increased range of motion occurs because of dance activities or a focused program of stretching to increase turnout. Rather many feel that lack of range may force young dancers to choose a danced idiom that requires less turnout and thereby dancers with limited turnout are selected out of the ballet population. There are other ROM challenges that may be discovered. For example, excessive external tibial torsion may align the patella medial to the second toe during plié, rather than directly over the second toe, which is considered proper alignment.2 Dancers and their teachers may choose different movement strategies and make appropriate turnout adjustments particularly during the valuable training years when ROM information is provided. Those who force turnout may choose to turnout less and those with differences between active and passive turnout may institute strengthening or stretching programs.

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niques for measuring and comparing TPT and TAT have begun to appear in the literature. Refining and combining these measurement approaches could yield important benefits for dancers and those who treat and train them. Armed with this ROM information, dancers may be empowered to make independent and informed decisions regarding biomechanically appropriate stance, which may affect dance training and other aspects of dance technique. Additionally, proper use of turnout may affect their health. Future studies should address the validity and reliability of these measurement techniques.

Summary Commonly used ROM measurement techniques are designed to measure isolated joint function. The disadvantage of these techniques is that they do not include all lower extremity contributions to total turnout. Tech-

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Acknowledgments I thank Judith R. Peterson, M.D., for her consultation; my colleague Julie Greenwood, M.S.P.T., for providing suggestions, organizing the photography session, and modeling; and Emily Sorelle and Jessica Latshaw for patiently modeling.

References 1.

Emotional Considerations Although potentially helpful, measuring turnout is not a panacea and may elicit an emotional response. Dancers may be disappointed when turnout measurement does not meet expectations and resist making changes. Compliance may be encouraged by certain strategies such as: approaching change incrementally, demonstrating how proper use of turnout enhances dance technique by facilitating the dancer’s sense of physical control, and discussing the limited role of ideal turnout in the multidimensional art form of dance. It is helpful for some dancers to hear that many inspiring dance artists have succeeded with less than ideal turnout.

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32. Trepman E: Biomechanics of the foot and ankle. In: Lutter LD, Mizel MS, Pfeffer GB (eds): Orthopedic Knowledge Update, Foot and Ankle. Rosemont, IL: American Academy of Orthopaedic Surgeons, 1994, pp. 1-19. 33. Kotwick JE: Biomechanics of the foot and ankle. Clin Sports Med 1(1):19-34, 1982. 34. Holmes CF, Wilcox D, Fletcher JP: Effect of a modified, low-dye medial longitudinal arch taping procedure on the subtalar joint neutral position before and after light exercise. J Sports Physical Ther 32(5):194-201, 2002. 35. Khan KM, Bennell K, Selena N, Matthews B, et al: Can 16-18 year old elite ballet dancers improve their hip range of motion over a 12month period? Clin J Sports Med 10(2):98-103, 2002. 36. Bennell KL, Khan KM, Matthews BL, Singleton C: Changes in hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and

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controls: A 12 month follow up study. Brit J Sports Med 35:54-59, 2001. Clippinger-Robertson KS: Biomechanical considerations in turnout. In: Solomon R, Minton SC, Solomon J (eds): Preventing Dance Injuries: An Interdisciplinary Perspective. Reston, VA: American Alliance for Health, Physical Education, Recreation, and Dance, 1990, pp. 75102. Kisner C, Colby LA: Range of Motion. In: Kisner C, Colby LA (eds): Therapeutic Exercise: Foundations and Techniques. Philadelphia: F. A. Davis Company, 1985, pp. 19-67. LiGreci-Mangini LA: A comparison of hip range of motion between professional ballerinas and age-/sexmatched nondancers. Kinesiology and Medicine for Dance 16(1):1930, 1993-94. Cibulka MT, Sinacore DR, Cromer GS, Delitto A: Unilateral hip rotation range of motion asymmetry in patients with sacroiliac joint regional pain. Spine 23(9):1009-1015, 1998.