Porter & Schon: Baxter's The Foot and Ankle in Sport, 2nd ed.

Section 4 - Unique Problems in Sport and Dance

Chapter 21 - Foot and ankle injuries in dancers

John G. Kennedy,
Christopher W. Hodgkins,
Jean-Alain Columbier,
William G. Hamilton


CHAPTER CONTENTS

  

 

Introduction

  

 

Metatarsophalangeal joint

  

 

Great hallux interphalangeal joint

  

 

Lesser metatarsophalangeal joints

  

 

Metatarsal injuries

  

 

The medial ankle

  

 

Lateral ankle

  

 

Anterior ankle

  

 

Posterior ankle

  

 

Achilles tendon

  

 

Heel pain

  

 

Leg pain

  

 

Summary

  

 

References

Introduction

Ballet has all the elements of the arts in its makeup—drama, poetry, literature, painting, sculpture, design, music, and, of course, dance. Dancers, both male and female, are the physical means by which the choreographer sculpts a composition of expressive motion. The grace and art of the ballet performance belie the great physical strain on the body as a whole and the foot and ankle in particular. From an early age the dancer must learn to be an artist, gymnast, and athlete. Most ballet dancers train for a minimum of 10 years before attaining the skill set necessary to join a corps de ballet. Very few dancers develop into soloists and fewer still attain the role of principle ballerina. Throughout this time of training, the body is placed under great strain, and it is by a process of natural selection that those dancers who are flexible and technically proficient survive the rigors of training to advance further.

Female dancers spend a considerable time en pointe, or on the points of the toes ( Fig. 21-1 ), whereas male dancers tend not to dance on their toes and spend much of their time in turning, lifting, and holding ballet dancers. As such, male and female dancers tend to present with distinct injuries. In addition to the myriad of physical injuries related to female dancers that follows, female dancers also are prone to the triad of anorexia, amenorrhea, and osteoporosis. This unfortunate triad stems from the significant pressure on dancers to weigh less and less. The most disturbing data suggest that female dancers weigh more than 15% below the ideal weight for height. This has metabolic consequences leading to stress fractures and slower union rates in injured female dancers.[1] In contradistinction, male dancers have fewer metabolic problems but are prone to overuse injuries from repetitive motion and to stress fractures from the sudden deceleration of large leaps, volé, sauté, or jeté.

 
 

Figure 21-1  Illustration of the en pointe stance.

 

 

Dancer's feet are the instruments on which their art depends. They require, in addition to an extraordinary flexibility and strength, a particular anatomic profile. Over time a dancer's foot will evolve and only the strongest will survive. Dancers’ feet typically are “intrinsic plus:” they have narrow metatarsal width with straight toes. (Intrinsic-minus feet have wider metatarsal splaying and clawing of the toes.[2]) Apart from muscle strength, dancers’ feet require great flexibility. In the relevé position ( Fig. 21-2 ) the ankle is in a vertical position—90 degrees of plantarflexion of the ankle-foot complex. The dancer also requires 90 to 100 degrees of dorsiflexion in the first metatarsophalangeal (MTP) joint to go from relevé to en pointe. These are extraordinary ranges of motion and can only be achieved with years of practice, which mold the young ballet dancer's bones during the bone growth phase. [0030] [0040] [0050] As a result of endless practice barres, class, and training, dancers’ feet tend to be cavus and have thickened metatarsals to support when en demi-pointe. Calluses abound secondary to pressure demands on the skin.

 
 

Figure 21-2  Illustration of the relevé stance (demi-pointe).

 

 

In general, five types of dancer's feet have been described:[6]

  

1   

Grecian (also known as Morton) foot has a relatively long second and third metatarsal in relation to the first and fifth metatarsal. However, dancers do not have the same problems associated with transfer metatarsalgia as does the general population with this foot configuration.

  

2   

Egyptian foot. Long first ray relative to the central metatarsals. This can predispose the first MTP joint to degenerative arthrosis or hallux rigidus.

  

3   

Simian foot. Metatarsus primavarus with hypermobile first ray that causes transfer metatarsalgia to central metatarsal heads.

  

4   

Peasant foot. Uniform metatarsal length, giving broad, square foot. Its stability makes it an ideal platform for dancing.

  

5   

Model's foot. This foot is long and slender with a taper exaggerated cascade from first to fifth metatarsal head. As such, it bears weight unevenly on demi-pointe and is a poor foot for dance.

The following is a review of the more common dance injuries and problems in the foot and ankle.

 

Metatarsophalangeal Joint

Bunions

Although dancing has been said to play a role in the pathogenesis of bunions, it is unlikely that this is the case. Dancers, like the rest of the population, can be either resistant or prone to develop bunions.[7]In those dancers that are prone to develop bunions, it is imperative to delay surgical intervention for as long as possible. Bunion surgery adversely affects dorsiflexion of the first MTP joint, a critical motion in dancers. Most bunions can be treated with conservative methods, including toe spacers and horseshoe pads. The senior author has seen several aspiring young dancers whose careers were ended by well-meaning bunion surgery. If a bunion is precluding the dancer from activity and surgery is warranted, then a chevron osteotomy can provide pain relief and stability without compromising motion.

Hallux Rigidus

Any restriction to full dorsiflexion of the first MTP joint will prevent the dancer from performing relevé. Many dancers can accommodate by rolling out onto the lateral border of the foot, a process known as “sickling.”

The treatment of hallux rigidus depends on the grade of the disease ( Fig. 21-3 ).

 
 

Figure 21-3  Illustration of hallux rigidus.

 

 

In grade I disease, the joint is preserved and marginal osteophytes can be resected, with excellent outcome expected.

In grade II disease, the joint is involved, with minor cartilage destruction evident as joint space narrowing on plain radiograph. Treatment involves resection of marginal osteophytes (cheilectomy). In addition, the dorsal one third of the metatarsal head is resected.[8] Intraoperative dorsiflexion of the hallux greatly overestimates the degree of motion that can be expected following surgery. Just over half of what is achieved at the time of surgery will be evident in the postoperative follow-up examination. It is important that dancers understand that, although surgery will make the condition better, the joint will never be normal. In addition, the length of recovery time must be discussed with the dancer, because a full functional recovery often takes 6 months. To improve functional motion following surgery, a dorsally based closing osteotomy can be used (Moberg). This procedure improves dorsiflexion but at the expense of plantarflexion, and the dancer should be warned of this.

In some cases we also can use a shortening scarf osteotomy to decompress the MTP joint and allow reestablishment of the mobility.

Grade III hallux rigidus presents with dorsal and lateral osteophytes in addition to clear degenerative arthrosis on both sides of the joint. Arthrodesis, an acceptable surgical option in the general population, is not feasible in a career dancer. To preserve motion, a capsular arthroplasty can be performed with reproducible outcomes[9] ( Fig. 21-4, A and B ). It is important to select these patients carefully because transfer metatarsalgia is common in those patients with a foreshortened first ray.

 

 

Figure 21-4  (A) Diagrammatic representation of an interpositional arthroplasty of the first metatarsophalangeal joint. (B) Intraoperative photograph of an interpositional graft in situ.

 

 

Injuries to the Sesamoid Bones

The sesamoid bones lie within the substance of the flexor hallucis brevis tendons. They are commonly injured in dancers, particularly in those who fail to perform a plié on landing, absorbing the energy of the landing through partially flexed knees. Without such absorption built into a dancer's technique, sudden deceleration with high impact of the sesamoid bones predisposes to injury.

Sesamoiditis

The differential diagnosis of sesamoiditis is lengthy and requires careful history taking and clinical examination. Magnetic resonance imaging (MRI) aids diagnosis. The following is a list of differentials:

  

   

Stress fracture of the sesamoid bone,

  

   

Avulsion fracture or sprain of the proximal pole of the sesamoid,

  

   

Sprain of the distal pole,

  

   

Sprain of a bipartite sesamoid,

  

   

Arthrosis of the sesamoid metatarsal articulation, and

  

   

Preradiographic osteonecrosis of the sesamoids.

Several mechanisms are responsible for producing sesamoiditis in dancers. Most of theses can be treated with a felt pad around the sesamoid for relief (“dancer's pad”). In general, symptoms resolve without any additional interventions although this may take up to 6 months for full resolution. In those cases requiring further diagnostic testing, a bone scan or MRI can be useful. The medial sesamoid is often bipartite, with rounded edges on plain radiograph, distinguishing it from a recent fracture.

In those cases with recalcitrant pain, surgery is warranted. A medial-based incision can locate the medial sesamoid; however, a plantar incision is always needed for a lateral sesamoid. Partial excision is preferred to prevent varus or valgus malalignment. Surgery should be reserved for those patients with symptoms persisting for at least 6 months following initial treatment.

Other conditions may mimic sesamoiditis, including instability, bursitis, and nerve entrapment:

  

1   

Sesamoid instability. Rarely, the medial collateral ligament of the tibial sesamoid is torn, causing a clear “clunk” as the sesamoid dislocates laterally when the dancer relevés. Repair of the medial collateral ligament usually requires release of the lateral ligament as an adjunct. The medial ligament may be frayed or not repairable end to end. In this case, local soft tissue is used to supplement the repair. Care must be taken not to overtighten the medial aspect of the joint and disrupt MTP joint motion.

  

2   

Sesamoid bursitis. Swelling and inflammation within the sesamoid bursa may mimic sesamoiditis. However, careful clinical examination usually can identify a symptomatic bursa when present. Treatment consists of a well-directed local corticosteroid injection to the bursa. Bursitis still may take some time to resolve, and it can be complicated by a fibrous scar that causes repeated symptoms. In such cases, a bursectomy can be performed through a careful plantar incision. Care should be taken in identifying the proper digital nerve, and a precise and meticulous skin closure is critical to a good outcome.

  

3   

Joplin's neuroma. Entrapment of the proper digital nerve, adjacent to and, rarely, under the tibial sesamoid, will cause symptoms similar to sesamoiditis. Joplin's neuroma, however, will display a characteristic nerve compression sign with palpation. In those cases recalcitrant to conservative therapy, neurolysis and transposition of the nerve are required.

Lateral Proper Digital Nerve Entrapment

The lateral proper digital nerve may be compressed under the deep transverse ligament, causing pain in the great toe on the lateral side. Because of the position of the nerve, a compression test cannot be performed. Diagnosis is made with a selective local anesthetic injection to the nerve. Surgical resection of the transverse ligament is curative.

 

Great hallux interphalangeal joint

In young ballet dancers, hyperflexion of the great toe interphalangeal joint (IPJ) can occur when attempting en pointe. Here, weight is distributed over the nail and dorsum of the toe in the pointe shoe.

Hyperextension of the great toe IPJ also occurs, usually to compensate for lack of motion in adjacent joints. Rarely does this need surgical intervention, despite radiologic appearances, because the joint is quite accommodating and typically asymptomatic. In those who do complain of symptoms, lambs wool wrapping can help to alleviate the discomfort problem.

 

Lesser Metatarsophalangeal Joints

Metatarsalgia is uncommon in dancers, and when it is encountered the differential diagnosis must include MTP instability and Freiberg's infraction.

MTP Instability

As the dancer relevés the phalanx subluxes dorsally, pushing the metatarsal head plantarward and causing pain. In the demi-pointe position, excessive loads are transmitted through the second and third MTP joints. Clinical examination will elicit a translation in the anterior-posterior (AP) plane that is in excess of the adjacent joints.[10] Treatment initially is directed at taping to neighboring toes and stress-relieving padding. Surgical correction includes a very limited resection arthroplasty with a plantar condylectomy. Alternately, a limited Weil osteotomy may be used with screw fixation. Motion is begun early. Scarring at the plantar aspect of the wound facilitates tightening of the redundant plantar plate.

Dislocation of the MTP joints

Acute injuries should be reduced and immobilized until soft-tissue healing can occur. In cases of delayed diagnosis, reduction often is impossible secondary to scarring and the risk of neurovascular stretching. In such instances, a resection arthroplasty or Weil osteotomy reducing the length of the metatarsal will facilitate reduction.

Freiberg's Infraction

Dancers have a propensity to develop Freiberg's infraction equal to that of the general population. In general, conventional radiography lags behind clinical symptoms by up to 6 months ( Fig. 21-5 ). Bone scan or MRI facilitate early diagnosis.

 
 

Figure 21-5  Preoperative and postoperative radiographs of Freiberg's infraction.

 

 

Four types of infraction occur:

  

   

Type I: A localized osteonecrosis of the metatarsal head that heals by creeping substitution. No cartilage defect is seen.

  

   

Type II: Following metatarsal head osteonecrosis, the structural support of the head is lost. New bone formation occurs but is not sufficient to prevent collapse of the head. The articular cartilage is preserved; however, osteophytes on the dorsal lip limit dorsiflexion. Surgical debridement is curative, with exostectomy of the dorsal ridge to facilitate dorsiflexion.

  

   

Type III: In addition to metatarsal head collapse, the articular cartilage is destroyed. Surgical management includes excision of the dead bone and cartilage and osteophyte resection. The plantar aspect of the joint usually is intact and can be left alone.

  

   

Type IV: A rare entity with several heads involved. May represent a congenital epiphyseal dysplasia rather than a true infraction.

Idiopathic MTP synovitis

Characterized by the appearance of a “sausage toe,” this clinical entity is associated with MTP joint laxity and instability. Anti-inflammatory medication and taping may provide benefit. If surgical exploration is required, a very limited resection arthroplasty with a plantar condylectomy is used. Alternately a limited Weil osteotomy is performed if the ray is long and plantarflexed relative to adjacent metatarsals. Scarring at the plantar aspect of the wound causes the plantar plate to tighten by scarring fibrosis. Motion is encouraged early to facilitate the flexibility needed by the dancer. This is a fine balance between flexibility and instability.

 

Metatarsal Injuries

Second Metatarsal Base Stress Fracture

Most high-level dancers have a mild cavus foot, and despite the mechanical advantages this creates vis-à-vis technique, the rigidity of the foot places high stresses on the bones on impact.[11] In those dancers who start their careers early in life, the metatarsals hypertrophy and the cortices broaden to accommodate the increased stresses placed on them. In certain cases, however, stress fractures occur despite cortical hypertrophy because the repeated microtrauma of dancing exceeds the reparative capacity of the bone.

Because of the cuneiforms’ Roman arch configuration, the second metatarsal sits wedged between the medial and lateral cuneiform bones. This causes a relative rigidity to the second ray and consequently a potential site for a stress fracture. In fact, this is the most common site for a stress fracture in the dancer's foot, and when a patient complains of pain and tenderness in the base of the second metatarsal, it should be regarded as a stress fracture until proven otherwise ( Fig. 21-6 ).

 
 

Figure 21-6  Stress fracture of the second metatarsal neck.

 

 

Conventional radiographs may not show the fracture, but a bone scan or MRI will confirm clinical suspicion in such instances. As the second metatarsal hypertrophies from years of pressure in the demi-pointe position, it may have the appearance of a healing fracture. Again, MRI can be useful in determining the true diagnosis.

Acute injuries require a cam walker for up to 6 weeks to allow time for the fracture to consolidate. Cast immobilization usually is not required, provided that the dancer can be trusted to keep the cam walker in place as prescribed. Rarely, a fracture may progress to a delayed union, and in these cases a small ultrasound bone stimulator can be used to accelerate healing.

Fifth Metatarsal Fractures

  

1   

Spiral diaphyseal fracture of the fifth metatarsal. These fractures occur when the dancer rolls over onto the lateral border of the foot from a demi-pointe position.[12] The fracture invariably heals but may take several months to heal sufficiently to allow further dance.

  

2   

Jones fracture of the proximal diaphysis. This is a difficult fracture to treat in a dancer because it requires extensive time in a nonweight-bearing cast ( Fig. 21-7 ). Nonunions are rare in a nonweight-bearing cast despite the tenuous blood supply. Weight-bearing casts, on the other hand, have a greater risk of nonunion. Should nonunion occur, a single screw down the diaphysis is required. This may or may not need to catch the medial cortex, depending on the grip of the screw within the diaphysis. Bone graft may be used as an adjunct to help osteosynthesis. If the screw is removed, the fracture has a significant risk of recurring.

  

3   

Avulsion fracture of the fifth metatarsal. Usually caused by sudden inversion of the foot, the peroneus brevis attachment is avulsed, in addition to the lateral band of the plantar fascia and the abductor digiti minimi. In general this injury can be treated with immobilization and rarely requires surgical intervention, because a fibrous union will invariably occur even in the presence of significant distraction of the fragments. In a skeletally immature dancer, this apophysis will not have ossified and the fracture will not be visible on plain radiographs. The diagnosis must be made clinically. The treatment is similar.

 

 
 

Figure 21-7  Jones fracture.

 

 

Bunionettes

Pain over bunionettes usually can be diminished with soft padding or Micropore adhesive tape to reduce friction and callus formation. Surgical resection usually is reserved for a retired dancer because the time to recovery from the procedure is extensive.

 

The Medial Ankle

Although posterior tibial tendon pathology is relatively common in other sports, it is rare in dancers. The reasons for this are multiple. Typically a dancer's foot is cavus, which tends to protect him or her from tibialis posterior pathology in comparison to a more planus foot. Also, when a dancer is in equines, the posterior tibial tendon is relatively shortened as the subtalar joint is inverted.

Medial Ankle Sprains

Medial ankle sprains occur infrequently and are associated with a pronated foot landing off balance. If the foot is in plantarflexion, the anterior deltoid is maximally affected, and the tension is greatest in the deltoid in this position. Similarly, when the foot is flat on the ground and hyperpronated, the tear will occur in the midportion of the deltoid.

An accessory bone, the os subtibiale, can be found in the substance of the deltoid. When injured, it may manifest as a trigger point of pain when ligamentous healing should be complete. A local injection of steroid is all that is required to treat this symptom.

Chronic strain of the deltoid from poor form in rolling in (pronation) of the foot is a common overuse injury in dancers. Chronic strain of the anterior aspect of the deltoid ligament, anchored to the capsule of the talonavicular joint, may predispose the ankle to chronic rotatory instability.

Recalcitrant medial ankle pain also may be caused by osteochondritis dissecans of the talus following a sprain. Clinical suspicion warrants further investigation with computed tomography (CT) or MRI, which will demonstrate the extent of the lesion ( Fig. 21-8, A and B ). The size of the osteochondral lesion determines the most appropriate treatment. Microfracture treatment, chondrocyte transplant, allograft implants, and osteochondral grafting are available techniques.

 

 

Figure 21-8  Magnetic resonance imaging (MRI) scan demonstrating coronal (A) and sagittal (B) views of an osteochondral defect (OCD) in the talus.

 

 

Osteochondral autologous transplant surgery (OATS) is indicated for large lesions with cartilage collapse or deficit and extensive underlying bone necrosis. The lesion is cored out of the talus and filled with osteochondral autograft, commonly from a nonweight-bearing location in the lateral femoral condyle ( Fig. 21-9, A and B ).

 

 

Figure 21-9  (A) Talus after “coring” of the osteochondral defect (OCD). (B) Talus following implantation of the autologous osteochondral graft.

 

 

 

Lateral Ankle

Lateral Ankle Sprain

The most common injury in dancers involves the lateral ligament ankle stabilizers.[13] The anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) are stressed at different ankle positions. The ATFL sprains in a plantarflexed and inverted foot, whereas the CFL is more prone to injury when the foot is dorsiflexed.

Three grades of tears commonly are seen:

  

   

Grade I: Partial tear, usually of the ATFL. This is a stable injury, requiring rest, ice, compression, and elevation for 48 hours. Thereafter, motion is encouraged with a light compressive bandage. Dancers can begin light workouts at 48 hours with the aid of a brace or Aircast. Initially, therapy should concentrate on range of motion. After 4 or 5 days, dancers begin to wean out of the brace and initiate proprioception, balance, and peroneal strengthening exercises.

  

   

Grade II: Complete tear of the ATFL, occasionally including the CFL as well. A positive drawer sign but negative talar tilt are observed. Treatment is immobilization in a cam walker or Aircast for up to 6 weeks. Initially, physical therapy should focus on regaining appropriate range of motion. Thereafter, a triple-phase rehabilitation program including peroneal strengthening, balance, and proprioceptive training should be initiated early.

  

   

Grade III: Unstable injury. Both the ATFL and the CFL are injured. In addition, the drawer sign and talar tilt are positive. Treatment traditionally is immobilization for up to 4 months. In a professional dancer, primary repair is preferred, and the Brostrom-Gould usually can be performed 1 week following the injury with predictable results and return of function.[14] Regardless of the treatment used, attention must be paid to reestablishing a functionally stable joint. A comprehensive literature evaluation and meta-analysis showed that early functional treatment produced the fastest recovery of ankle mobility and earliest return to activity without affecting mechanical stability.[15] Closed chain balance and proprioception activities, along with peroneal muscle strengthening, will improve the neuromuscular control of the ankle. A therapist must be familiar with the modalities needed to achieve these goals to optimize outcomes in these dancers.

Residual symptoms following lateral ankle sprains in dancers may be secondary to:

  

1   

Avulsion fracture of the tip of the fibula,

  

2   

Accessory ossicle or os subfibularae,

  

3   

Os calcis fracture or avulsion of extensor digitorum brevis,

  

4   

Fractured os peroneum,

  

5   

Fractured lateral process of talus,

  

6   

Cuboid subluxation,

  

7   

Soft tissue entrapment,

  

8   

Sinus tarsi syndrome,

  

9   

Fractured os trigonum or Shepherd's fracture,

  

10   

Syndesmotic disruption,

  

11   

Maisonneuve injury,

  

12   

Anterolateral gutter scarring or Ferkel's phenomenon,

  

13   

Talar irritation from a slip of the ATFL inserting at the extreme tip of the fibula or the Bassett's ligament,

  

14   

Peroneal tendon dislocation or subluxation,

  

15   

Functional ankle instability, or

  

16   

Impingement of a lateral branch of the deep peroneal nerve (LBDPN).

LBDPN Impingement

Persistent dorsolateral foot pain following ankle sprain is common. It often is attributed to chronic ligament dysfunction, sinus tarsi syndrome, anterior tarsal tunnel syndrome, or functional ankle instability. The pain is triggered most commonly in a plantarflexed and inverted position. In those cases recalcitrant to a rehabilitation program, an impingement of an LBDPN over the anterolateral corner of the talus (Fig. 21-10 ) or underneath the extensor digitorum brevis (EDB) muscle should be sought. Diagnosis is confirmed with persistent pain, exclusion of the above differentials, a positive Tinel's sign over the anterolateral talus, and response to a localized subcutaneous anesthetic injection.

 
 

Figure 21-10  Illustration of branching pattern of the lateral branch of the deep peroneal nerve (LBDPN).

 

 

Shoewear modification can often alleviate any external compression. However specifically guided injections and ultimately release of the EDB is often necessary.[16]

 

Anterior Ankle

The cavus foot is ideal for dancers in that plantarflexion is maximal. However, this is at the expense of dorsiflexion, which is limited. The most common form of anterior impingement typically is seen in male dancers who perform high jumps and deep pliés (bravura). Impingement of the anterior lip of the tibia against the talus causes the cambial layer of the periosteum to produce reactive bone formation and osteophytes or “kissing lesions.”[17] This is a continuous cycle as more bone forms, and eventually motion is significantly restricted.

Three main types of lesions are seen ( Fig. 21-11 ):

  

1   

Anterior tibial lip,

  

2   

Talar neck, or

  

3   

A combination of both.

 

 
 

Figure 21-11  Radiograph of tibiotalar osteophytes.

 

 

Treatment of type I is resection using the arthroscope. Type II and III lesions often may require an anterior arthrotomy. Attention always should be directed to the medial joint whether using an arthroscopic approach or a formal arthrotomy. A medial impingement exostosis on the talus that impinges on the medial malleolus can be found and resected.

 

Posterior Ankle

Ideally, more than 100 degrees of plantarflexion should occur at the foot-ankle complex in a professional ballet dancer. Much of this has to be accomplished by the subtalar joint, and subtalar motion is facilitated by the turned-out position of mild forefoot pronation and abduction. Any form of tarsal coalition, whether fibrous or bony, will prevent the subtalar joint from supplementing the ankle joint in full equinus. Consequently, most dancers with subtalar coalitions do not reach professional grade.

Posterior Impingement Syndrome

The posterior tubercle of the talus varies greatly in size. In posterior impingement syndrome, either a large posterior tubercle or an os trigonum ( Fig. 21-12, A through C ) is caught between the posterior lip of the tibia and the os calcis when the dancer is in relevé.[18] A simple clinical sign, the forced plantarflexion sign, confirms the diagnosis when pain is produced by full plantarflexion at the back of the ankle. The syndrome is usually a result of an os trigonum impinging the soft tissue rather than the bone itself. The differential diagnosis includes Achilles tendinitis, peroneal tendinitis, or heel pain.

 

 

Figure 21-12  (A) Radiograph of an os trigonum. (B) Radiograph of an os trigonum in relevé. (C) Illustration of os trigonum posterior impingement.

 

 

The os trigonum is present in up to 10% of the population and is bilateral 50% of the time. Anatomically, the os trigonum represents the nonfused lateral process of the talus. This forms the lateral border of a fibro-osseous tunnel, the medial border being the medial talar tubercle. Through this tunnel runs the flexor hallucis longus. Most cases of an os trigonum are asymptomatic in the general population, and this is also true in dancers. However, in dancers this condition often is operated on unnecessarily. For this reason, a diagnostic injection of local anesthesia is mandatory before any surgical intervention. If there is no subsequent pain relief, one must seek an alternative diagnosis such as:

  

1   

Flexor hallucis tendinitis (FHL) tendinitis,

  

2   

Peroneal tendinitis,

  

3   

Hairline or stress fracture of the posterior process,

  

4   

Localized coalition, or

  

5   

Osteoid osteoma.

Treatment of an os trigonum generally is nonsurgical. Once a diagnosis has been confirmed by local anesthetic injection, the next step is rest and activity modification. Local steroid can give dramatic relief of symptoms that often is long lasting or permanent. When surgery is required, either a posteromedial or posterolateral approach can be used. In cases in which it is suspected that there is an associated FHL tendinitis, a posteromedial approach is preferred so that tenolysis can be performed safely.

Posterior impingement also may occur following a lateral ligament sprain. With lateral ligamentous laxity, the talus slips forward and the posterior lip of the tibia impinges on the os calcis. Treating the lateral ligament instability usually addresses this form of impingement.

A pseudomeniscus, with or without an os trigonum, causes another, less common, form of posterior impingement. This embryologic remnant, similar to a plica, can cause symptoms of locking and pain following a tear in its substance.

Flexor Hallucis Longus Tendinitis

This entity has become known as “dancer's tendinitis.”[19] As the tendon passes between the fibro-osseous tunnel at the back of the talus, it runs deep to the sustentaculum tali. Within this pulley system it can become inflamed and cause irritation and swelling. When the tendon has a partial tear or becomes swollen at a particular area, it may cause triggering ( Fig. 21-13 ). This condition is known as hallux saltans.[12] When the tendon becomes completely stuck down within the pulley system, a pseudohallux rigidus can be seen. Treatment of this condition requires a compliant patient to rest. Anti-inflammatories are a useful adjunct. Local steroid injections should be avoided whenever possible. When the condition is recurrent or disabling surgical, tenolysis is warranted. Three areas of FHL tendinitis typically are found. The most common location is behind the medial malleolus. It also may be found at the knot of Henry, or at the base of the first metatarsal where the tendon passes beneath the sesamoid bones.

 
 

Figure 21-13  Flexor hallucis longus tendinosis.

 

 

 

Achilles Tendon

As the largest tendon in the body, the Achilles tendon incurs forces up to six times body weight during running and jumping.[1] Therefore the tendon is commonly injured in dancers either from repetitive overload or excess stress applied by poor technique. Although a common site of injury in dancers, the tendon is rarely ruptured in this group of athletes.

Peritendinitis of the Achilles Tendon

The Achilles tendon has no real synovial sheath and is surrounded by a peritendon, which can become inflamed from overuse or from the tight ribbons of ballet shoes. The peritendinitis is classically seen as a diffuse swelling along the Achilles tendon. When the tendon itself is inflamed, it presents as a discrete swelling along the tendon. Treatment of peritendinitis requires rest. A cam walker with a heel-raise insert worn for 23 hours/day should be worn for at least 2 weeks. This can break the cycle of inflammation and prevent the next step in the continuum of pathology—inflammation of the tendon itself.

Tendinitis of the Achilles Tendon

Tendinitis is caused by microtears of the collagen fibers on the surface or in the substance of the tendon. The most common form of tendinitis occurs at the isthmus of the tendon and involves a localized swelling of the pseudosheath. This may be felt clinically as crepitus when the tendon is stretched and relaxed—the so-called painful arc sign. Chronic tendinitis can be felt as multiple nodules on the surface of the tendon. More severe strains result in a classic fusiform swelling of the tendon. This is slow to heal and carries a guarded prognosis.

Treatment requires rest initially, usually in a cam walker with a heel-raise insert for up to 6 weeks. This should be worn continuously, including bed, for the first 2 to 3 weeks. Failure to comply with strict immobilization initially can result in prolonged symptomatology and rupture of the tendon. Treatment can be supplemented with anti-inflammatory medication. Rehabilitation consists of stretching exercises and a gradual strengthening program. In more chronic cases, use of an overnight splint to assist with a prolonged stretch in a dorsiflexed position can be helpful. Orthotic prescription may be considered to help correct any structural imbalances in the foot. A “stretch box” is a useful tool to prevent injury that is used by many ballet schools. This allows dorsiflexion of the ankle with stretching of the Achilles tendon before and between performances. However, dancers must exercise caution to avoid stretching the Achilles tendon too aggressively, causing more tears and thereby worsening the condition.

Certain factors can predispose to tendinitis in dancers:

  

1   

Cavus foot with associated Haglund's disease ( Fig. 21-14 ), with tendinitis of the Achilles overlying the retrocalcaneal bursa. Cavus feet are common in this population, because they afford the dancer a distinct anatomic advantage. For this reason, any prominence at the posterosuperior aspect of the os calcis can cause irritation of the tendon. This may necessitate resection of the prominence ( Fig. 21-15 ).

  

2   

“Rolling in” or pronation of the foot.

  

3   

“Ribbon burn” from tight toe ribbon at the back of the leg.

  

4   

Congenitally thin tendon is predisposed to overload injury.

  

5   

Tight heel cord.

 
 

Figure 21-14  Cavus foot with Haglund's deformity.

 

 

 

 

Figure 21-15  Preoperative (A) and intraoperative (B) radiographs of Haglund's deformity.

 

 

Rupture of the Achilles Tendon

Achilles tendon ruptures are rare in female athletes and more common in male dancers older than 30 years. Typically a tear presents as a sharp pain of sudden onset and an inability to walk on the toes. A Thompson test is the best clinical diagnostic test. Feeling for a defect along the tendon usually is diagnostic; however, an intact peritendon filled with hematoma may mimic an intact tendon. Ultrasound can confirm the diagnosis with a high degree of sensitivity and specificity. Treatment is dependent on the requirements of the patient. Cast immobilization is associated with up to 30% rate of rerupture and will allow up to 80% normal strength and function. Operative intervention has the advantage of restoring the physiologic length and thus optimizing functional outcome. This requires up to a full year of treatment and rehabilitation before the dancer can return to preinjury levels of dance. Newer techniques of limited open incisions with percutaneous suturing facilitate early motion and reduce the risk of associated skin problems.[20] Correct tensioning of the repair is critical to outcome regardless of the technique used.

Pseudotumor of the Calf

An accessory soleus muscle can present as a slowly enlarging mass on the medial side of the calf. It generally is painless, usually presenting as a feeling of tightness. Surgical division of the muscle sheath will generally relieve the symptoms.

 

Heel Pain

  

1   

Heel spurs syndrome: The spur usually is not the cause of heel pain, despite often-impressive radiographic evidence. The plantar fascia is not intimately attached to the spur, giving rise to the flexor digitorum brevis. A silicone heel can give symptomatic relief in a dancer who has point tenderness in this area.

  

2   

Plantar fasciitis: Pain on the medial aspect of the fascia origin is the most common presentation. Stretching of the fascia before rehearsing or performing can reduce the incidence of this injury. Also, using a firm rubber ball for rolling into the plantar fascia while weight bearing helps to loosen the fascia and make it more pliable.

  

3   

Plantar calcaneal bursitis: Found beneath the calcaneus, this condition usually can be diagnosed clinically; however, ultrasound can confirm the diagnosis.

  

4   

Baxter's nerve neurapraxia: The first branch of the lateral plantar nerve or nerve to abductor digiti minimi may be trapped under the deep fascia of the abductor hallucis.[21] This is exacerbated when the dancer “rolls in” or pronates. Although the cause is a neurapraxia of the lateral branch of the plantar nerve, the condition is painful on the medial aspect of the heel, adjacent to the medial calcaneal tuberosity. A local anesthetic directed into the area may make the diagnosis. Surgical resection of the fascia yields excellent outcomes.

 

Leg Pain

The three primary conditions in dancers that predispose to leg pain include shin splints, stress fracture, and compartment syndrome.

Shin Splints (Medial Tibial Stress Syndrome)

“Shin splints” is a generic term often used to describe both traction periostitis and stress fractures. It has gained credence in the general population to describe generalized leg pain. A more useful nomenclature is medial tibial stress syndrome (MTSS). For the purposes of this discussion, MTSS describes a traction periostitis alone. This condition is associated with a diffuse anteromedial or posteromedial tibial pain. Typically the pain is in the distal one third of the tibia. It can be differentiated from stress fracture, which has localized point tenderness and usually is in the middiaphysis of the tibia and distal one third of the fibula.

Typically, MTSS occurs at the beginning of the season after a prolonged period of inactivity. Stress fractures typically are from repetitive trauma and occur usually in mid to late dance season. Posterior MTSS is most common in dancers and arises at the origin of the flexor digitorum longus (FDL), and not from the tibialis posterior, which arises from the interosseous membrane. Anterior MTSS, not as common in dancers, represents a periostitis at the origin of the tibialis anterior muscle. Soleus syndrome, pain at the posteromedial aspect of the medial malleolus, is caused by an abnormal slip of soleus muscle. Treatment is a decrease in activity, cross training, and isometric exercises in addition to well-cushioned shoes. Rarely, a fasciotomy of the soleus insertion may be required.

Stress Fractures

Prolonged biomechanical imbalances and increased repetitive loads beyond the body's reparative capacity typify the causes of stress fractures. Thus these injuries generally occur at the end of the dancer's season, in contradistinction to MTSS, which occurs at the beginning. In the initial phases radiographic evidence may be slim, and the best method of confirming a clinical suspicion is a bone scan or MRI. Delayed subtle periosteal reaction occasionally can be seen ( Fig. 21-16 ).

 
 

Figure 21-16  Tibial stress fracture.

 

 

In chronic stress fractures, conventional radiographs may reveal the “dreaded black line” seen on the anterior aspect of the tibia. This represents granulation tissue in a slowly healing fracture. The line is an indicator that the fracture will be slow to heal, requiring at least 6 to 8 months. In a competitive dancer this is an extremely long period. A drilling procedure may be used to accelerate healing and can be performed using a small drill percutaneously with the aid of a FluoroScan, if available. The drill is used to penetrate the anterior cortex and stimulate neovascularization and callus formation. Return to activity is titrated against radiographic healing of the stress fracture line. Since the introduction of Balanchine method of dance, which emphasizes fluid motion, the number of stress fractures has reduced. This is in contrast to the rapid deceleration motion seen in the Bravura technique.

Compartment Syndrome

When the pressure within an enclosed fascial compartment exceeds the pressure required to perfuse the muscle with blood, the muscles and enclosed structures may become compromised. This can lead to pain initially and may reach the point of muscle ischemia in more severe cases. In dance, the blood volume to the exercising muscle can increase up to 20%, thereby exceeding the physiologic pressure within the muscle compartments. Most cases of exertional compartment syndrome involve the anterior compartment or the deep posterior compartment. Normal resting compartment pressures range from 0 to 8mm Hg. During exercise this can increase to 50mm Hg. Following exercise, this pressure should fall to 15mm Hg within 15 minutes. Treatment of exertional compartment syndrome usually is conservative, with anti-inflammatory medication and shoe modification, as well as activity modification. Rarely, a fasciotomy is required. Careful attention to ruling out a high tarsal tunnel syndrome should be made before embarking on a fasciotomy in a dancer.

 

Summary

Classical ballet offers a graceful and beautiful spectacle. This beauty comes at great physical, psychological, and economic cost to the ballet dancer.[22] It is estimated that up to 95% of dancers employed for greater than 1 year will suffer a significant injury. Most of these physical injuries occur to the foot and ankle in female ballet dancers.[23] Many of these injuries are as a result of dancing on the point of the toe. This form of dancing was first performed by Genevieve Gosselin in 1818 at the Paris Opera house. The illusion of weightlessness and the grace implied in en pointe dancing was further enhanced by the great dancers Taglioni and the immortal Istomina. Since their time, the beauty, romance, and grace of en pointe have been enjoyed by dancers all over the world. Unfortunately, the “cruel little slipper” that is the en pointe shoe, as well as the physical demands of the dance itself, have left many dancers with significant injuries and permanent deformities.

It must be emphasized that, when the orthopaedist examines a ballet dancer, the entire kinetic chain requires close inspection. Isolated injuries to the foot and ankle may precipitate additional injuries farther up the kinetic chain as a compensatory response to the injury or inadequate and improper rehabilitation.[24] Apart from the physical examination, a careful history and biochemical profile should be investigated in those dancers showing any signs of the aforementioned dancer's triad: anorexia, amenorrhea, and osteoporosis.[25] In addition to the biomechanical examination and biochemical evaluation, the orthopaedist should be cognizant of the psychosocial aspects of a dancer's makeup. Dancers, in general, regard injury and pain as a way of life and are reluctant to present to health care professionals for fear of long-term immobilization and eventual unemployment. [0220] [0260] As an advocate for the dancer as an athlete, the clinician should be aware of these concerns and strive to provide an accurate diagnosis and expeditious treatment strategy.

 

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