Where the joy of dance and play intermingle. Photo by Igor Burlak, Courtesy of Boston Ballet School
Here I would like to emphasize that it is up to the individual dancer, especially as she progresses into adolescence, to be as informed as possible about her own anatomic and biomechanical status during all phases of training, in order to resist doing damage that may not appear until years later, or could inhibit healthy progress through a long dance career. The basic take-away message from this chapter is that one really can dance from beginning to end of a career and beyond without causing hip pathology.
Although it is frequently mentioned in the literature of dance pedagogy, the widespread condition known as “snapping hip” is seldom taken seriously enough to be subjected to in-depth study. Nor does it tend to receive anywhere near its proper due in the dance studio. As this syndrome is intimately associated with several highly debilitating injuries in dancers, most notably iliopsoas tendinitis and acetabular labrum tears, it seems vitally important to raise awareness of its true significance among dancers and their teachers.
Clicking and popping about the hip in athletes and dancers is a common phenomenon, and generally remains asymptomatic. In certain circumstances, however, especially where the hip is subjected to frequent and extreme hyperextension and external rotation, the same condition that produces these sounds (the “snapping” tendon) may cause pain severe enough to restrict or prohibit activity, and therefore requires medical attention. This painful snapping hip is most frequently encountered in dancers, gymnasts, and soccer players, who make very heavy demands on the iliopsoas muscle-tendinous unit for both strength and endurance, and therefore are especially prone to hypertrophy of these structures, setting the stage for derangement of the iliopsoas mechanism at the anteromedial aspect of the hip .
Early reports of snapping hip treated the condition as a single entity involving movement of the tensor fascia lata or iliotibial band over the greater trochanter on the lateral aspect of the hip [2–6]. With Moreira  and especially Nunziata , however, a distinction came to be made between this variety and an “internal” snapping hip experienced in the groin area on the anterior aspect of the hip. Initially, some observers suggested that this medial snapping was due to a tear of the labrum, and in some instances surgical exploration of these hips was carried out . However, subsequent investigative studies, spearheaded by Schaberg et al. [10, 11], demonstrated that it results from the iliopsoas tendon snapping over the neck of the femur. This finding was subsequently replicated by several other investigators [12–14]. Deslandes et al. found that the hip movement that generates the snapping consists of bringing the hip from flexion-abduction-external rotation back to the neutral position. According to these authors the snapping is provoked by the sudden flipping of the iliopsoas tendon over the iliac muscle, allowing abrupt contact of the tendon against the pubic bone and producing an audible snap .
Internal snapping hip poses a greater problem for the population at risk than the external variety, as the pain associated with it tends to be more intense and therefore more debilitating. The doctors with whom I work in the Sports Medicine Division of Children’s Hospital in Boston, headed by Dr. Lyle Micheli, were apparently the first to propose that this pain is the result of a stenosing tenosynovitis of the iliopsoas tendon near its insertion on the femur—essentially, an iliopsoas tendinitis . Others implicate the iliopsoas bursa, which lies between the iliopsoas tendon and the anterior hip capsule [17, 18]. Whether the injury we are attempting to manage is strictly defined as a tendinitis, a bursitis, or damage done by a simple anatomical malfunction, the preferred initial treatment involves: “relative” rest; the use of anti-inflammatory medication and therapeutic modalities such as deep heat or ultrasound; anti-lordotic exercises; and peripelvic stretching and strengthening exercises, particularly of the iliopsoas, both for immediate relief and to correct the biomechanical conditions that caused the problem in the first place . To this we have recently added ultrasound-guided injection, either intra-articular or into the psoas bursa (see Chap. 10 for a more complete discussion of these procedures). Ultrasound is a convenient and low-risk tool that can be used to aid in the diagnosis of common injuries seen in the adolescent dancer and as imaging guidance for diagnostic and therapeutic injections.
These “conservative” measures have generally been found to be quite efficacious [19–25], particularly if diagnosis is made early and intervention begun immediately thereafter. Unfortunately, many dancers and their teachers tend to dismiss snapping hip in its early stages as a minor mechanical problem. In other cases, ineffectual treatment which simply approaches it as an inflammatory condition, without attempting to correct the excessive tightness and muscle imbalances about the hip that precipitated it, can result in persistence of this condition to the point where chronic inflammation of the tendon sheath and bursa occurs . Once this point is reached medical interventions up to and including surgery, all of which portend at the very least a prolonged rehabilitation and potentially even the end of a dance career, may appropriately be considered.
As an aside, it should be mentioned that when discussing snapping and pain about the hip one must consider the possible differential diagnosis of a labral tear, a condition that can mimic, or even exist simultaneously with, iliopsoas tendinitis . Labral tears of the hip are associated with painful and unpredictable catching sensations in the groin, especially with internal rotation at 90° of hip flexion and abduction. Anderson posits that labral tears may be related to subluxations (which I discuss below in the section on microinstability) and underlying acetabular dysplasia . No one has actually witnessed the emergence of a labral tear; hence, our understanding of the etiology of this injury remains somewhat theoretical . On the other hand, anyone who has ever danced (especially ballet), or witnessed dance with an anatomically critical eye, will have no problem conceptualizing the mechanism of injury. Simply to stand in first or second position, with the feet “turned out” to 180°, rotates the head of the femur in the acetabulum to an extent that most people seldom experience in their daily lives. When the dancer elevates the leg through développé into the various extensions front, side, and to the rear that are an essential component of all choreography, this rotation is carried to truly unique extremes. As the dancer performs these maneuvers hundreds (perhaps thousands) of times over the course of a typical work week, it is not surprising that the labrum occasionally tears.
In medical circles there is a belief that one etiology for labral tears involves an underlying structural abnormality in the hip. While it is no doubt true that such abnormalities are often contributing factors in the development of labral tears, it is our belief that these factors are secondary to what is widely understood to be the basic mechanism of most dance injuries in general: The labral tear is just another overuse injury that results from the interplay between the dancer’s unique anatomy and the extreme demands of the art form. Dancers who develop this condition are simply among those relative few whose hips could not stand up to the rigors of the daily routine, or, alternatively, whose faulty dance technique exacerbated the effect of the routine on the anatomy.
Fully fifty percent of the dancer-patients seen at our clinic over the past three years have presented for assessment and treatment of hip pain. The most frequently diagnosed injuries were labral tears, “snapping hip” syndrome (iliopsoas tendinitis), muscle-tendon strains, stress fractures, and joint disease (e.g., chondral defect, or degenerative joint disease). Labral tears were the most common, accounting for forty percent of the total hip injuries and twenty percent of injuries generally in this population . In his summary of these findings, Dr. Kocher states that dancers and their teachers should be educated on reliable strategies for avoiding hip injuries. A focused rehabilitation program of peripelvic conditioning and biomechanically sound dance technique may obviate the need for operative treatment. Prevention, he says, is clearly preferable to surgery .
In the context of complications associated with labral tears and chondral flaps, some mention should be made of degenerative joint disease (DJD). DJD may contribute to the initial onset of labral injury in the hip. Of even greater concern is the risk to any hip in which labral damage has occurred of developing long-term DJD after the original injury has been treated. Any dancer who undergoes arthroscopic hip surgery should be aware that the relief produced thereby may be temporary; resulting DJD could cause recurrent problems at some future date .
As indicated previously, in its early stages medial snapping hip is usually painless, and therefore seemingly benign. It is only with repetition over time that the tendon becomes irritated and inflamed enough to stick in its sheath and sustain the tearing and scarring that characterize tendinitis. This no doubt explains in part why many dance teachers advise that snapping hip is really nothing to worry about unless it is painful. Such advice may also mask an ignorance of how to correct dance technique to eliminate the snapping. At any rate, it is widely known that dancers are prone to snapping hip, and one might well wonder why more of them do not progress to iliopsoas tendinitis.
Our theory is that when many dancers say their hips snap/click/pop they mean occasionally; that this is something they have experienced and taught themselves to avoid by subtly altering their technique when performing hip abducting movements (many dancers can intentionally snap their hips; hence, it is to some extent a controllable phenomenon). The unfortunate few who come to us with full blown iliopsoas tendinitis are those who have taken too much to heart the ill-informed injunction not to worry about the snapping until there is pain.
It should be obvious by now that in this author’s view responsible dance teachers must be alert to evidence of snapping hip in their students and learn how properly to respond to it. In fact, the appropriate response is a fairly simple matter. First, take the situation seriously yourself and see to it that the student involved does the same. Second, reach a mutual agreement with that student that it will be all right for her to work at less than 180° of turnout (no matter what the other students in class are doing) until you both feel that she is ready to “go for it.” Third, make a permanent part of your teaching repertory exercises that are intended to aid the student in identifying her proper placement in turnout, and provide the wherewithal to increase the height of her extension within that range. This includes specific mechanisms for extending range of motion and developing the strength (particularly of the iliopsoas muscle complex) required to achieve whatever turnout and extension are possible given the individual student’s anatomical limitations. (For an extensive demonstration of such exercises see this author’s video, “Anatomy as a Master Image in Training Dancers.”) .