There are many common extrinsic and intrinsic causes of injury and risk factors in dance. One extrinsic factor is the type of dance floor. The presence of adequate shock absorption and the degree of surface friction can lead to injuries of the knee, foot, and ankle if there is too much surface resistance. Likewise, a floor that is too firm leads to fatigue and injuries such as tendonitis of the leg and foot (8).

Footwear can also influence injuries. Most ballet dancers wear either slippers, composed of only fabric or leather and no structural support, or pointe shoes, which are made of a solid toe box, metal or wood shank, and fabric. Theoretically, pointe shoes act as an additional stabilizer of the foot as demonstrated by cadaveric studies (9). However, these shoes are not designed to provide adequate stability or shock absorption and have changed very little since the 1600s (4,8). Furthermore, principal dancers may wear out one to three pairs of pointe shoes per performance because if the shoe becomes too soft it can often lead to injury, such as tendonitis and stress fractures (9).

Intrinsic causes of injury or risk factors include, but are not limited to: malalignment of the lower limbs, muscle imbalance, and inappropriate training (7,8,10,11). Proper alignment in ballet is based on turnout (the maximal amount of external rotation at the hips), which will ideally enable a dancer to stand with the feet placed at 180 degrees in first position. Although dancers may appear to be able to achieve 160 to 190 degrees of turnout at the feet, they may not have the corresponding degree of external rotation at the hip (12,13). When the lower extremity is properly aligned in first position (14,15), the knee flexes directly over the foot. Many students will not be able to attain this ideal position and will compensate by forcing their turnout. “Rolling in” forces the feet into a position with a valgus heel and forefoot pronation (Fig. 55-5), leading to subsequent collapse of the medial arch and thereby increasing the torque on the ankle and knee (Fig. 55-6) (7,9,11). Young dancers, both female and male, will sometimes increase their lumbar lordosis in order to tip the pelvis anteriorly and thus obtain increased hip rotation. In addition to potentially leading to low back pain, other complaints may arise from the increased torque placed on the lower limb (7,11).

Muscle imbalance is often due to inadequate strength or altered flexibility. Ballet emphasizes hip flexion, external rotation, and abduction, which can lead to weakening of the antagonist muscles (8). Deficits in strength and endurance at the hip may lead to injuries of the foot, ankle, and knee (21, 22, 23). Focusing the treatment on the injured joint without addressing any underlying hip muscle imbalances may frustrate both dancers and physicians alike as pain and dysfunction are likely to recur. By nature, dancing en pointe involves loading the ankle joint in maximal plantar flexion with accompanying distal pressure placed on the first and second toes. Significant ankle flexibility and intrinsic foot strength are required to maintain the position (9). Elite and professional dancers usually display appropriate alignment as such alignment problems typically extinguish careers prior to this level. Generally speaking, at the professional level, limb injuries more often result from overuse rather than from issues of alignment. In young dancers, immature skeletal formation may contribute to musculoskeletal injury. Similarly, growth spurts may further lead to muscle imbalances, where a gain of 1 to 3 in. in growth might overwhelm the muscular strength required to move and change positions. As a result, young dancers can develop muscle tightness relative to bone length and/or inadequate strength, particularly in the hip rotators (16).

The effects of inappropriate training are often related to factors such as excessive duration and intensity (7,10). As in other aesthetic sports that place a large degree of importance on the appearance of the performer such as diving and figure skating, dancers often have delayed menarche due to caloric restriction coupled with large amounts of exercise (17). As dancers are often subjectively judged on their appearance, eating disorders are common in preprofessional dance schools with some reports estimating up to 30% of the students being effected (18, 19, 20). Such behavior can often place dancers at increased risk of developing the “female athlete triad”: disordered eating, amenorrhea, and osteoporosis (7,10).

Dancers routinely suffer spine injuries similar to many other athletes, including but not limited to fractures of the pars interarticularis and sacroiliac dysfunction. Delay in the treatment of pars fractures may progress to fibrous unions that will not calcify and potentially result in spondylolisthesis. If underlying biomechanical issues are corrected within an appropriate time frame, dancers may continue dancing with spondylolisthesis. However, dancers should restrict activity with relative rest in the event of a new pars fracture and may require either an antilordotic modified Boston brace or a nonspecific conventional lumbar corset (26).

Sacroiliac pain occurs frequently and is often difficult to resolve (7,27). Jumping and leg extension on the affected side may incite pain in dancers experiencing sacroiliac dysfunction. Special physical examination maneuvers such as Gaenslen’s test and the Gillet’s test are useful in diagnosis. Treatment of sacroiliac dysfunction may include mobilization of the joint and pelvic stabilization exercises.

Repetitive microtrauma from extreme extension or hyperextension may result in damage to posterior elements, such as the pars interarticularis, facets, pedicles, and spinous processes (28). Poor technique and control may cause painful injuries to the periosteum during hyperextension. Although this injury is painful, it requires no special treatment other than correction of technique unless it proceeds to pars fracture.

“Snapping hip” accounts for 50% of hip problems in dancers, occurring either medially or laterally with or without pain (4). When it occurs laterally, the iliotibial band or tensor fascia lata snaps anteriorly and posteriorly over the greater trochanter when landing from a jump in poor turnout and with excessive anterior pelvic tilt (7) or as the thigh moves between the anterior and posterior positions. “Snapping hip” may also occur medially and is sometimes referred to as “iliopsoas syndrome” (29) (Fig. 55-7). This phenomenon occurs when a hypertrophied iliopsoas crosses the femoral neck when bringing the hip into extension during a semicircular motion known as rond de jambe (7) (Fig. 55-8). A dancer with this injury will experience intense anterior groin pain during this arcing movement, particularly as the iliopsoas stretches over the femoral head from medial to lateral; it is also typically more painful while in the air than with the foot on the floor (30). “Snapping hip” rarely causes significant disability and responds well to
focused stretching, hip strengthening (especially the external rotators, adductors, and internal rotators), and antilordotic postural control (11,30). Other hip injuries such as labral tears, osteoarthritis, stress fractures of the femoral neck, hip avulsion injuries, and femoral neuropraxia have been described in the medical literature as well (7).

Knee problems are often attributed to insufficient hip strength in external rotation or forcing greater foot turnout than physiologically possible (as noted previously). Hip weakness or alignment problems are the usual causes of knee pain. The typical sports-related knee injuries also occur in dancers, including anterior and medial collateral ligament sprains, patellar subluxation, and patellofemoral syndrome (31,32). Tears and injuries often result from slips, twisting falls, and improper landings from jumps. Diagnosis and rehabilitation of such injuries follow standard sports medicine guidelines.

Ankle sprains are the most common acute dance-related injury (7). These sprains commonly occur when a dancer loses balance while landing from a jump while the foot is in plantar flexion. They can also occur from rolling over the lateral aspect of the foot while on demipointe (9). Interestingly, in full pointe, the ankle is relatively stable as the posterior lip of the tibia locks on the calcaneous and thus the subtalar joint locks in varus. It should be noted, however, that slight dorsiflexion relaxes the chain and may predispose the ankle to injury (10). As noted with other sports, the anterior talofibular ligament is the weakest ankle ligament and most susceptible to injury (9,10). The Ottawa ankle rules recommend ankle radiographs if a patient is unable to walk three steps or if there is tenderness over either malleoli (10). Specific rehabilitation of acute ankle injuries includes pool therapy, plantar flexion exercises, proprioceptive retraining, and peroneal strengthening with an emphasis on resuming full mobility of the talar, subtalar, and transverse tarsal joints (7,9).