Tarsal Coalition: Surgical Management in the Young Athlete

Abstract

Tarsal coalition is an abnormal bony, cartilaginous, or fibrous bridge between 2 or more tarsal bones. Adolescent athletes with tarsal coalitions typically present with symptoms that include foot and/or ankle pain and limited range of motion. Loss of mobility can lead to abnormal loading, articular instability, deformity, and joint degeneration. Nonoperative management includes immobilization, physical therapy, and custom foot orthosis. Surgical options include coalition excision and fat graft interposition, foot realignment, or a combination of these. Surgical treatment requires evaluation of the coalition type, foot alignment, and degenerative changes in the adjacent joints.

Introduction

A congenital condition that is a common cause of foot pain and ankle injuries in young athletes, tarsal coalition is an abnormal bony, cartilaginous, or fibrous connection between 2 or more tarsal bones. It results from failure in differentiation and segmentation of primitive mesenchyme between the 9th and 10th week of pregnancy. It is believed to be an inherited autosomal dominant condition with high penetrance [18,19]. Symptoms typically arise during adolescence (between the ages of 10 and 19 years, as defined by the World Health Organization [43]) and include pain referred to the foot or ankle, stiffness, and limited range of motion of the foot [4]. True incidence is unknown, although it is estimated to vary between 1% and 13% [32] and can be bilateral in 50% of cases [28]. The most common subtypes are calcaneonavicular coalitions (CNCs) and talocalcaneal coalitions (TCCs), which together account for 90% of cases [37]. Abnormal unions may consist of bony tissue (synostosis), fibrous tissue (sinfibrosis), or cartilage (synchondrosis). Cartilaginous coalitions in younger patients can ossify in adolescence, corresponding with the onset of symptoms during this period.

Coalitions may restrict range of motion in the subtalar joint, which is essential in foot and ankle biomechanics [31]. Loss of mobility can lead to abnormal loading, articular instability, deformity, and joint degeneration [8]. Maximum mobility and stability are required in sports that involve repetitive axial loading, direction changes, or sudden stops. Restrictions in foot eversion and inversion can lead to injuries such as repetitive ankle sprains [35] and stress fractures [2,16,40]. Pain associated with sport practice can significantly affect performance in elite adolescent athletes. Also, adolescence is a time of substantial growth, weight gain, demanding training, and high-intensity activity, all of which may aggravate symptoms [25]. This article reviews the diagnosis, treatment, and outcomes of tarsal coalitions in young athletes.

Diagnosis

Diagnosis is typically made with plain foot and ankle radiographs: anterior to posterior (AP), lateral, and oblique weightbearing radiographs of the foot. A Saltzman view can also help in the evaluation of hindfoot alignment. Calcaneonavicular coalitions are best seen on oblique radiographs, identified by either a solid osseous coalition or a fragmented sclerotic abnormal joint. When seen on a lateral radiograph, the elongated anterior process of the calcaneus resembles the long snout of an anteater (“anteater sign”). A talocalcaneal coalition may be seen on an axial (Harris) radiograph. On the lateral X-ray, there may be narrowing of the posterior facet of the subtalar joint or a C-shaped line along the medial outline of the talar dome and the inferior outline of the sustentaculum tali (“C sign”). The C sign is caused by bony connection in the middle facet. In some cases, a talar beak can also be seen on the lateral view; this results from an alteration in the distribution of stress. Although plain films may be diagnostic, when a coalition is suspected a computed tomography (CT) scan is the imaging modality of choice. In addition to securing the diagnosis, a CT scan helps define the degree of joint involvement, provides detailed information of the osseous anatomy of coalitions, and rules out associated coalitions and degenerative joint changes [9]. Weightbearing computed tomography (WBCT) allows excellent evaluation of foot and ankle deformities, enabling improved visualization of the joint under natural load at a reduced cost and radiation exposure [10]. Magnetic resonance imaging (MRI) may be more effective in identifying fibrous coalitions or in making a differential diagnosis for foot pain [21].

Conservative Treatment

Only symptomatic tarsal coalitions require treatment. For asymptomatic tarsal coalitions—revealed as incidental findings on plain radiographs after a minor trauma—observation is required. When a tarsal coalition becomes symptomatic, it is important to assess the patient’s activity level, sport type, foot alignment, pain intensity and location, and the range of motion of the foot and ankle. Nonoperative treatments considered in patients with mild-to-moderate symptoms may include analgesia, immobilization in a short-leg cast or walking boot, physical therapy, custom foot orthosis, and activity modification. However, this approach is not possible in most young athletes [1]. Historically, symptomatic relief to delay or obviate surgical intervention was achieved through subtalar corticoid injections or image-guided steroid injections. Nonetheless, these procedures do not appear to decrease the need for surgery [44]. Data are limited on outcomes after conservative treatment of symptomatic tarsal coalitions [33]. In our experience, conservative management does not resolve clinical symptoms because it does not modify the biomechanical disturbances caused by tarsal coalitions. Therefore, most patients who become symptomatic ultimately require surgical management, although conservative treatment can be offered until the end of the competitive season.

Surgical Treatment

Surgery is indicated in patients with persistent symptoms or considerable restriction in sport and daily activities. In addition to pain relief and mobility improvement, the aim of surgery is to prevent degenerative changes and future injuries. The gold standard is open surgical resection of the coalition with fat autograft interposition to prevent recurrence of the union (Fig. 1) [27,39]. Although operative treatments such as arthroscopic/endoscopic resection have been proposed, they are associated with higher revision rates than open treatment [5].

Fig. 1.

Calcaneonavicular coalition in a symptomatic 12-year-old girl. (a) Oblique radiograph showing fibrous calcaneonavicular coalition. (b) Photograph showing Ollier’s approach. (c) Fluoroscopic image of the resection margins before and after resection. (d) Autologous fat graft preparation and insertion in the gap.

Surgical approach varies according to the size, type, foot alignment, and degenerative changes in adjacent joints. To resolve symptoms, simple resection of CNC with autologous fat is highly effective [12,22,27]. Occasionally, patients with CNC may present with flatfoot or cavus foot, but severe deformity is uncommon; therefore, realignment procedures associated with bar resection are infrequent. Surgical treatment of TCC is more challenging due to the complex anatomy of the subtalar joint and because they are commonly associated with foot deformity. The authors’ preferred surgical approach for TCC can be grouped into the following categories:

• Coalition resection and fat graft interposition. It is indicated in symptomatic cartilaginous or bony middle facet TC coalitions without degeneration (narrowing) of the posterior facet on coronal CT scan images.

• Coalition resection and foot reconstruction. It is indicated in symptomatic cartilaginous or bony middle facet TC coalitions without degeneration in the posterior facet and severe flatfoot deformity [23,26]. We favor single-stage coalition resection and foot realignment (Fig. 2). Reconstruction consists of lateral column lengthening (LCL) or a double calcaneal osteotomy (LCL ± medial sliding calcaneal osteotomy) in more severe deformities. After hindfoot correction, clinical intraoperative assessment of the forefoot is required. By pushing up on the bottom of the forefoot, the surgeon can feel the balance of the first ray in relation to the lateral rays by placing 1 thumb of each hand on the first and fifth metatarsal heads, respectively [14]. The presence of a rigid supination deformity of the forefoot requires a medial cuneiform osteotomy (MCO) to restore the weightbearing tripod of the foot and prevent a recurrence of foot collapse. Often, following correction of hindfoot deformity, forefoot supination becomes more evident and a MCO is required. Soft tissue surgery in the form of peroneus brevis lengthening and gastrocnemius recession (GR) or an Achilles tendon lengthening (ATL) is usually undertaken. When deciding between GR or ATL, the surgeon may conduct a Silfverskiöld test. Typically, this test is performed after coalition resection, as it necessitates the inversion of the subtalar joint to a neutral position.

Fig. 2.

An 11-year-old female field hockey player with right foot pain and severe malalignment. (a) AP and lateral radiographs of the right foot demonstrate severe flatfoot, nonvisualization of the middle subtalar joint, and a complete “C” sign, suggestive of talocalcaneal coalition. (b) Coronal and 3-dimensional (3D) CT scan demonstrates a severe malalignment of the hindfoot associated with an osseous talocalcaneal coalition. (c) Intraoperative image after coalition resection and foot realignment (calcaneal lengthening osteotomy, medial cuneiform dorsal opening wedge, and Achilles tendon/peroneus brevis tendon lengthening).

• Foot reconstruction. Foot realignment without coalition resection is indicated in a bony coalition with narrowing (degeneration) of the posterior facet. Typically, these cases manifest as severe flatfoot deformities, and the associated pain is more likely attributable to the flatfoot deformity with tendo-Achilles contracture rather than to the coalition itself. The reconstruction process adheres to the principles outlined in the preceding section. Arthrodesis is reserved for instances where the aforementioned procedures prove unsuccessful or in patients exhibiting severe joint degeneration. However, it is noteworthy that arthrodesis is generally not the primary procedure performed in this age group.

Outcomes After Coalition Resection

Although tarsal coalition surgery is relatively common, it can be difficult to evaluate clinical outcomes. A recent systematic review [11] analyzed 43 articles comprising 1284 feet, with a pooled mean follow-up of 51 months. The authors pointed out that most studies do not detail foot alignment or coalition morphology. Furthermore, the authors used the methodological index for nonrandomized studies (MINORS) instrument [34] to assess the quality of methodology in these studies; it was found to be fair [11]. Noncomparative studies had an average MINORS score of 9.8 (range = 5-12) out of 16. Comparative studies were scored at an average of 16.5 (range = 11-20) out of 24. Treatment was defined successful when a “good” or “excellent” result was achieved at follow-up. When utilized, an American Orthopaedic Foot and Ankle Score (AOFAS) or Foot and Ankle Ability Measure (FAAM) score above 80 was considered successful treatment. With the use of other ankle-hindfoot–related scoring methods, a successful outcome was defined at 80% of the maximum score or higher. The overall pooled success rate for TCCs was 79% (95% confidence interval [CI] = 75-83%) and for CNCs was 81% (95% CI = 75-85%). Pooled complication rates of 4% (95% CI = 3-7%) for TCCs and 6% (95% CI = 4-11%) for CNCs were found. Most of the cited studies did not describe the physical activity level of the cohort or the rate of return to competitive sports after surgery.

Some authors [3,17,20,24] have proposed an arthroscopic approach for tarsal coalition resection to decrease scarring, reduce the morbidity of the procedure, and to shorten recovery. Corin et al [5] compared the clinical outcomes and complications in 127 patients treated with a CNC resection using either an arthroscopic (N = 81) or a classic open (N = 46) approach. The arthroscopic approach had a significantly longer operative time and higher revision rate than the open approach (15% vs 2% revision, P = .024).

Regarding interposition, materials reported to have been used include extensor digitorum brevis (EDB), autologous fat, bone wax, fibrin glue, adipofascial flaps, and deepithelialized skin flap grafts [7,22,29,36,41]. Masquijo et al [22] demonstrated that use of autologous fat graft from the gluteal crease as interposition after CNC resection was superior to EDB in patient-reported outcomes and re-ossification/recurrence rates.

There is scarce information about clinical outcomes of coalition surgery in athletes; studies are mostly limited to small case series or case reports [13,15,38,42]. Elkus [6] reported excellent results in 20 athletes (25 feet) who underwent bar resection. All had improvement in motion, decreased pain, and return to athletic activity. Morgan and Crawford [25] studied 8 adolescent athletes diagnosed with tarsal coalition. Following surgical resection, 5 of 6 patients who had calcaneonavicular bar excisions as well as 2 patients with talocalcaneal bar excisions returned to competitive athletics. O’Neill and Micheli [30] evaluated 16 athletes (mean age = 13 years) with tarsal coalitions; 18 feet had resection of the tarsal coalition and EDB interposition, and 2 feet had extra-articular subtalar arthrodesis. Nineteen of 20 feet (95%) had excellent or good postoperative outcomes, whereas 17 of 20 (85%) had excellent or good subjective outcomes. Two bars in 2 feet (10%), both in the same patient, recurred. All males returned to their previous level of competition in sports, whereas 3 female patients (3 feet) gave up sports. These studies were from 3 decades ago, when imaging and understanding of the calcaneopedal unit were limited, were retrospective in nature, and lacked patient-reported outcomes. Further studies with better research methodology and higher levels of evidence are required to assess the variables that influence outcomes.

In conclusion, tarsal coalition should be considered in adolescent athletes with persistent foot pain or recurrent sprains. Nonoperative measures may reduce pain and allow sports participation, but they do not modify biomechanical disturbances and seldom result in long-lasting symptom improvement. Surgical treatment requires an individualized evaluation of the coalition size and type, foot alignment, and degenerative changes in the adjacent joints. Surgical excision of tarsal coalitions with or without foot realignment has favorable outcomes and a low rate of recurrence.