Coalitions

Congenital abnormalities often become symptomatic when increased stress, such as intense activity, is applied to the area. Therefore an inactive child may not complain of pain until he or she enters organized sport and the congenital problem may appear to trigger the symptoms. In many congenital problems, the natural history is unmasked with the longer duration and increased intensity of the activity, although the developmental and growth stage actually may be the determining factor in the onset of symptoms. Tarsal coalition is one congenital abnormality that may present in later elementary- and middle school-aged athletes as they begin increasing their participation in organized sports.

Tarsal coalition is a congenital bridging of two or more tarsal bones of the foot, which can be either bony or soft tissue (cartilage or fibrous tissue). The overall incidence of tarsal coalitions has been noted in studies to range from less than 3% to as high as 12.9% of the population.¹ Coalitions can be seen between any two tarsal bones, but the two most common types are calcaneonavicular (bilateral in 60%) and talocalcaneal coalitions (bilateral in 50%).²

These athletes typically present when the coalition begins to ossify. In early childhood and at elementary school age, coalition bridging is mostly nonossified, which allows some motion between the bones and keeps these patients typically asymptomatic.³ Motion becomes restricted when the bridging begins to ossify between 8 and 12 years of age for the calcaneonavicular coalition and between 12 and 16 years for the talocalcaneal coalition. This often is a prime age for middle school and early high school athletes to raise the level of their play and intensity, thus giving the appearance that the increased sports activity is causing the symptomatic foot pain. In reality, the combination of the two factors probably is the main reason for symptoms.

The young athlete may complain of insidious onset of pain or remember an acute onset of arch, ankle, or midfoot pain. The pain can be vague or localized over the coalition and be due to many factors, such as inflammation of the joints, nerve irritation or entrapment, muscle spasm, and microfractures (stress fractures) within the coalition.^4,5 Any adolescent athlete with an inversion ankle injury that does not resolve after a full rehabilitation program should have tarsal coalition in the differential diagnosis. Other athletes who have not experienced an injury can present with pain located in the cuboid/navicular area that is aggravated by increased impact activities.

On physical examination, the patient classically presents with a valgus heel, pronation deformity, and abduction of the forefoot. The pronation deformity is rigid, meaning that the arch does not reform when nonweight bearing and is stiff to clinical examination. Furthermore, a weight-bearing calcaneal valgus is present and fails to go into varus on toe raising. This is distinguishable from the usually asymptomatic flexible flatfoot, which re-forms its arch with nonweight bearing. Subtalar motion is diminished on examination. Passive inversion may elicit pain as the shortened peroneal tendon is stretched. Examination findings sometimes are subtle in early stages and may require further radiologic studies.

Radiologic evaluation begins with plain films, which include anterior-posterior (AP), lateral, and oblique views of the foot and a tangential view of the calcaneus. The AP may demonstrate a talonavicular coalition. The oblique angle best demonstrates the calcaneonavicular coalition. The tangential view of the calcaneus (Harris axial view) best demonstrates a talocalcaneal coalition (middle facet). Bone scan typically is not used but may have a place as a screening procedure in cases that are difficult to determine. The gold standard remains computed tomography (CT). It is used to confirm diagnosis, determine surgical planning, follow up postoperatively, and evaluate degenerative changes. Magnetic resonance imaging (MRI) is becoming more useful, particularly in the young, growing population. MRI can detect soft-tissue bridging before ossification takes place.⁶

Treatment initially should be conservative for young athletes with tarsal coalitions. Both rehabilitation with aggressive Achilles stretching and custom orthotics can be used to improve the biomechanics of the foot and improve symptoms. Immobilization also can be used at times during a season to help the athlete calm the symptoms and possibly finish a season. Surgical intervention usually is the long-term treatment for athletes and can be done during the adolescent years or as dictated by nonresolving symptoms with sports. Athletes with no significant degenerative changes can expect to have an excellent or good surgical outcome.⁷ Avoiding surgery in the young, symptomatic athlete may increase the risk of arthritis later in life.

Flexible Flat Feet

Flat feet, or pes planus/pes valgus, is a common problem in young athletes. Pes planus is a normal foot position up to 6 years of age.⁸ Most young athletes with flat feet are asymptomatic and do not require any intervention. Wenger et al.⁶ demonstrated that intervention with orthotics did not change the natural course of asymptomatic flat feet. The cause of this congenital problem is excess laxity of the joint capsule and ligaments, which allows the longitudinal arch to collapse during weight bearing. The arch re-forms when nonweight bearing and is accentuated with dorsiflexion of the first toe.

A full examination should be performed in a young athlete with flat feet, whether symptomatic or not. Among other questions in the history, the clinician should determine the length of symptoms, the effect of these symptoms on sports activity, and any systemic symptoms. Subtalar motion is one factor that can help differentiate pes planus from tarsal coalitions. The calcaneus should move passively between 20 and 60 degrees of inversion and eversion. When Achilles tendon flexibility is measured with the knee extended and the ankle/foot held in varus, ankle dorsiflexion less than 10 degrees below neutral indicates tight heel cords and may contribute to pes planus. If the athlete has no symptoms and the examination does not suggest a secondary cause, no further workup is necessary. These young athletes should be allowed to participate in all activities without restrictions. There is no evidence to date that preventative treatment with orthotics or other shoe inserts will prevent the development of symptomatic pes planus in the future. Children with unilateral, asymptomatic pes planus require more careful monitoring, as well as evaluation for neurologic and spinal causation.

If the athlete is seeking medical advice because of discomfort, then radiographs should be obtained to evaluate further for secondary causes. These may include accessory navicular, fractures, tumors, or coalitions.

Painful, flexible flat feet without secondary causes often respond to conservative measures. The young athlete must understand that this may be a chronic problem, but that extra work may help to alleviate the symptoms. Orthotics, aggressive heel cord stretching, and strengthening of the intrinsic muscle of the foot and posterior tibial muscle are the mainstay of treatment. Time also should be spent examining the footwear of young athletes. Worn-out shoes should be replaced with supportive footwear, especially a shoe with good medial longitudinal arch support.

Hallux Valgus

Bunions in children are less common than in adults. However, some studies have reported the prevalence to be as high as 35% in the adolescent population.⁹ Bunions of the great toe are more common in girls than in boys. The developmental etiology of bunions is multifactorial, with an association of ligamentous laxity, hypermobile forefoot, pronation deformity, and metatarsus primus varus with hallux valgus.^10,11 Shoes that place excessive stress on the first ray, such as narrow fitting and high heeled shoes, also are associated with increased irritation of bunions. Heredity is thought by some to play a role.¹² A young athlete with a congenital angle between the first and second metatarsals greater than 10 degrees is more prone to developing hallux valgus in the future.¹¹

Parents and young athletes alike need to be aware of proper-fitting shoes. Children with rapidly growing feet may need several shoe changes during a single year. Prevention of this condition is the best treatment. If symptoms begin, the child may need to weigh the benefits of flat, wide shoes outside of sports versus the looks of more trendy narrow, heeled shoes. As with adults, weight-bearing x-rays and a physical examination usually are warranted when a young athlete complains of pain over the first ray. Because the natural history of this condition occurs over many years, initial workup may find the exostosis and thickened bursa at the medial head of the first toe to be less impressive than findings in an adult. Adolescent bunions also differ from late findings in adults in the lack of arthritic changes and spurs.¹³

Treatment is similar to that for the adult with regard to conservative measures. These include proper footwear, avoidance of aggravating activity, nonsteroidal anti-inflammatory drugs (NSAIDs), heel-cord stretching, orthotics, and education. Surgery should be postponed until after maturation of growth because recurrence of the deformity after osteotomies and capsulorrhaphies is common in young athletes.¹⁴ Joint stiffness and discomfort at extremes of motion also is a problem for young athletes after surgery, and the athlete may never be able to return to his or her previous level.

Accessory Navicular

Most accessory bones about the foot and ankle are normal variants and often represent secondary centers of ossification. These variants often are asymptomatic and without clinical significance. However, some young athletes may develop symptoms that relate directly to the variant, such as the accessory navicular, or naviculare secundarium. The accessory navicular is one of several supernumerary ossicles first identified in 1605 by Bauhin (see Ref. 15). There are two types of accessory navicular. The first type is found within the posterior tibial tendon. The accessory navicular is present in about 10% of children; however, only 2% do not fuse by maturity. Anatomic studies have revealed that this accessory navicular ossicle is independent of the navicular bad break and can be thought of as a sesamoid bone.

The second type is an accessory ossification center medial to the navicular. During early development, this ossification center is surrounded by cartilage that is congruent with the cartilage of the navicular. The secondary ossification center typically fuses with the navicular near maturity, usually between 9 and 11 years. This type may be associated with symptomatic medial foot pain, especially in the adolescent athlete. This ossicle accounts for approximately 70% of all accessory naviculars.

The symptomatic accessory navicular should be thought of as an overuse injury. Increased stress on the overlying soft tissue causes inflammatory irritation and pain, especially if tenosynovitis has developed. It typically presents with pain and tenderness over the medial aspect of the foot, particularly the medial navicular. The athlete complains of pain with weight-bearing activity that is aggravated by tight-fitting shoes. The medial arch may be flattened secondary to posterior tibialis muscle fatigue or congenital foot pronation. Often the symptoms begin at the beginning of a new season. There is a higher predominance in girls than in boys, and the majority of patients first complain of symptoms during their adolescent years. Prominence is noted on the medial navicular on clinical examination.

Radiographically, the two types of accessory navicular should be distinguished because the first type does not commonly have symptoms. An oval or circular sesamoid on plain film is associated with the first type. Type II, or the commonly symptomatic ossicle, has a triangular and more irregular appearance.¹⁶ Bone scan of a symptomatic navicular will demonstrate an area of increased uptake over the medial navicular ossicle.

Treatment initially should be aimed at conservative measures. These include a period of avoiding aggravating activities and using orthotics to eliminate pressure over the prominence. If pain is intolerable, immobilization in a short walking boot with or without an orthotic may be helpful to eliminate the muscle spasm and discomfort. Surgery is reserved for the persistent symptomatic ossicle that does not respond to several months of conservative treatment.

Avulsion Fracture of Fifth Metatarsal

As in adults, young athletes often have inversion and supination injuries to their feet and ankles. In young athletes these inversion injuries often can lead to an avulsion fracture at the base of the fifth metatarsal. The middle school- or early high school-aged athlete will present with lateral foot pain and swelling. He or she typically notes a history of a significant inversion injury and the inability to continue participation. On examination the athlete will have palpable pain at the base of the fifth metatarsal that is more significant than pain at the lateral ligaments. Plain films of the foot, including AP, lateral, and oblique views, will easily detect the usually transversely oriented fracture. If concern exists regarding whether the plain films show a fracture or an unfused metatarsal physis, comparison films of the nonaffected foot may help to differentiate. Because this injury occurs with the injury mechanism commonly seen with lateral ankle sprains, the avulsion fracture may be missed if ankle films alone are obtained.

The most common fracture of the fifth metatarsal seen in young athletes is a transversely oriented avulsion fracture at the base of the fifth metatarsal and through the metaphysis. As noted previously, the injury commonly arises from an acute forceful inversion and supination injury of the foot/ankle. The mechanism is similar to twisting that produces lateral ligament injury of a sprained ankle. Recent cadaveric studies indicate that the lateral band of the plantar fascia is the structure responsible for the tuberosity avulsion, and not the peroneus brevis, as once thought.¹⁷ It generally does not involve the articular surface but occasionally may extend into the cuboid-metatarsal articulation.¹⁸ As mentioned, on roentgenographs this injury sometimes is confused with an unfused apophysis in a growing athlete.

If there is minimal displacement, conservative treatment is indicated using symptomatic immobilization. Our preference is to use a below-knee walking boot. However, a hard-soled shoe or a cast also is acceptable. The walking boot allows the athlete to almost immediately begin nonimpact conditioning with a stationary bike, stair-stepper machine, or elliptical trainer during the recovery time. After 3 to 4 weeks in the boot, the athlete can be weaned out of the boot into a steel-shank shoe insert. Limited impact sports activities can be started at 4 to 6 weeks while the steel-shank insert is worn, and progression is allowed using pain as a guide. Both plain films and symptoms are followed to assess healing. Radiographic healing may not be seen for several months and generally lags behind clinical symptoms.

A small percentage of avulsion fractures in young athletes will progress into nonunions. These athletes will have a history of a significant inversion injury that typically was treated with some type of immobilization. The athlete will present to the office over the next 6 to 24 months with the complaint of continued injuries and pain involving the base of the fifth metatarsal with sports activities. Plain films that include a comparison of the unaffected foot typically will be diagnostic. Surgical intervention then is typically required to allow the athlete to effectively return to sports.

Fifth Metatarsal Apophyseal Avulsion

The tendon of the peroneus brevis inserts into the apophysis. The apophysis can be distracted and avulsed with an acute inversion injury. Chronic repetitive stress results in Iselin’s disease, as discussed later in the chapter. Patients present with pain over the base of the fifth metatarsal, and there may be widening of the apophysis on plain films.

The normal apophysis is parallel to the long axis of the metatarsal. The apophysis develops between the ages of 9 and 11 in females and 11 and 14 in males. It typically fuses several years later.⁵

If there is minimal displacement, then nonoperative treatment consists of boot immobilization for 3 to 6 weeks followed by progression to running and then to sports (2-3 months). If there is more than 2 to 3 mm of displacement, surgery should be considered.

Os Vesalianum Sesamoid

This normal variant must be distinguished from an avulsion injury in the skeletally immature athlete.

Jones Fracture

As first described in 1902, the Jones fracture has a similar appearance to the avulsion fracture but is more distal in position.¹⁹ It is located about 1.5 to 2.0 cm from the proximal end, involving the metaphyseal-diaphyseal junction. This fracture also has a transverse orientation that is intra-articular. Although it commonly is described as occurring from an acute traumatic event, it can be secondary to chronic repetitive stress, such as from running.

This fracture is not commonly seen in the same age group as the fifth metatarsal avulsion fracture. It usually occurs in the older adolescent (15 to 20 years). Risk factors for this type of fracture include intense level of repetitive running and jumping, as seen in basketball and volleyball players. Another physical risk factor is the athlete who has hindfoot varus because of the increased stress of the lateral aspect of the foot. A high rate of delayed union or nonunion is due to the tenuous blood supply to this area.

Treatment for this fracture is somewhat controversial and is beyond the scope of this chapter. In general, we prefer to use intramedullary screw fixation if the growth plate is closed because it allows a quicker return to competitive sports as compared with bone grafting without screw fixation.

This fracture and its treatment options are discussed in Chapter 4.