You are in: eMedicine Specialties > Orthopedic Surgery > FOOT AND ANKLE Tarsal CoalitionArticle Last Updated: Nov 2, 2007AUTHOR AND EDITOR INFORMATIONAuthor: Louis Vu, MD, Consulting Staff, Department of Orthopedic Surgery, St Josephs Hospital and Medical Center Louis Vu is a member of the following medical societies: American Academy of Orthopaedic Surgeons Coauthor(s): Charles T Mehlman, DO, MPH, Director, Musculoskeletal Outcomes Research, Associate Professor, Division of Pediatric Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center Editors: James K DeOrio, MD, Director of Foot and Ankle Fellowship Program, Assistant Professor of Orthopedic Surgery, Orthopedic Surgery, St. Luke's Hospital, Jacksonville, Florida; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Shepard R Hurwitz, MD, Director of Clinical Services, Department of Orthopedic Surgery, University of Virginia School of Medicine; Director, Division of Foot and Ankle Surgery, Department of Orthopedic Surgery, University of Virginia Health System; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Jason H Calhoun, MD, FAAOS, Chairman, J Vernon Luck Distinguished Professor, Department of Orthopedic Surgery, University of Missouri Author and Editor Disclosure Synonyms and related keywords: peroneal spastic flatfoot, talocalcaneal coalition, TC coalition, calcaneonavicular coalition, recurrent sprain, ankle sprain, fixed flatfoot, foot pain, midfoot pain, ankle pain, middle facet talocalcaneal coalition, posterior facet talocalcaneal coalition, talonavicular coalition, calcaneocuboid coalition, anterior facet talocalcaneal coalition, fibrous cartilaginous coalitions, incomplete cartilaginous coalitions INTRODUCTIONTarsal coalition is a condition in which 2 or more bones in the midfoot or hindfoot are joined. The most common types of coalitions are those between the calcaneus and either the talus or the navicular bones. Patients with this congenital condition usually present during late childhood or adolescence, but presentations in adulthood have been reported. The condition usually presents as recurrent sprains and pain in the midfoot and has been associated with peroneal spastic flatfoot, fixed flatfoot, and other abnormalities of the foot (also see the eMedicine article Acquired Flatfoot and the Medscape article Flat Feet). Radiographic evaluation has been revolutionized by the use of CT scanning. Early treatment usually involves conservative modalities, including immobilization, while surgical intervention includes resection of the coalition or arthrodesis of degenerated painful joints.1, 2 History of the ProcedureIn 1969, Heiple and Lovejoy demonstrated the antiquity of tarsal coalition in the human gene pool by showing the presence of bilateral talocalcaneal bridging in a pre-Columbian Indian specimen.3 In 1965, Harris also mentioned the existence of the condition in Mayan archeological specimens found in Guatemala. The earliest known mention of tarsal coalition in the literature was by Buffon in 1796. In 1829, Cruveilhier wrote the first known anatomic description of calcaneonavicular coalition.4 Zuckerkandl first described middle facet talocalcaneal coalition in 1877, while Pfitzner first described the more rare posterior facet talocalcaneal coalition in 1896. Finally, Anderson described talonavicular coalition in 1879, and Holland first described calcaneocuboid coalition. Holl first theorized a relationship between tarsal coalition and peroneal spastic flat foot in 1880. Slomann first specifically linked calcaneonavicular coalition to peroneal spastic flatfoot in 1921 and theorized that the resection of the bar would be therapeutic. Badgley did the same in 1927 and first demonstrated the surgical technique of resection of the coalition as proper treatment.5 Finally, in 1948, Harris and Beath also linked talocalcaneal coalition to the same clinical problem.6 Kirmission performed the first radiographic demonstration of a tarsal coalition in 1898.7 Slomann, in 1921, demonstrated the usefulness of the lateral radiograph in identifying calcaneonavicular coalitions, while Korvin, in 1934, was the first to describe the special view for talocalcaneal coalition that Harris and Beath later popularized in their paper.6 In 1969, Conway and Cowell reviewed the radiographic characteristics of tarsal coalitions and first proposed the existence of an anterior facet talocalcaneal coalition.8 They also delineated the use of tomography in the evaluation of the different facets of the calcaneus. Goldman et al first suggested the use of bone scintigraphy as a screening tool for tarsal coalitions in 1982. Deutsch et al, in 1982, also evaluated bone scintigraphy along with CT scanning in 3 cases of talocalcaneal coalitions and found that the latter was better at providing detail of the coalition.9 Herzenberg et al, in 1986, attempted to identify the best CT views for evaluation of the different coalitions.10 Wechsler et al evaluated MRI as a viable tool in evaluation of fibrous or incomplete cartilaginous coalitions for which findings on CT scans might be inconclusive.11 ProblemTarsal coalition usually presents as recurrent sprains and pain in the midfoot and has been associated with peroneal spastic flatfoot, fixed flatfoot, and other abnormalities of the foot. FrequencyThe incidence of talocalcaneal coalitions in the general population is thought by most authors in the literature to be approximately 1%. Various authors have credited Pfitzner with the first incidence study but quote different percentages varying from 1.5-6% for overall incidence of tarsal coalitions to 2.9% for calcaneonavicular coalitions. Harris and Beath found 74 cases in 3600 consecutive prospective army recruits examined.6 Rankin and Baker found 24 cases in approximately 60,000 basic trainees at Fort Dix from 1971-1972 (0.4%),12 while Vaughn and Segal found 28 coalitions in 2000 cases of painful feet.13 Shands and Wentz found an incidence of 0.9% in cases of painful flat feet in a pediatric clinic.14 Leonard found in his survey of relatives of patients with symptomatic coalitions that 39% had asymptomatic coalitions.15 Snyder et al found that 91 of 223 (63%) young patients with ankle sprains had radiographic findings suggestive of tarsal coalitions.16 In an evaluation of 2982 complete skeletons collected from 1910-1940, Cooperman et al found that 26 of them had calcaneonavicular coalitions (incidence of 1.2%).17 Leonard found that all of the 76% of the first-degree relatives who had radiographic evidence of tarsal coalitions were asymptomatic.15 This would suggest that the actual incidence in the population may be higher than previously thought. In terms of the distribution of types, Stormont and Peterson found in a review of the literature that 48.1% of the tarsal coalitions presented were talocalcaneal and 43.6% were calcaneonavicular. In their own series, the distribution was 53% calcaneonavicular and 37% talocalcaneal. The literature overall mentions a bilaterality rate of 22-60% in talocalcaneal coalitions and 40-68% in calcaneonavicular coalitions, with most being just over 50%.18 Sex ratios vary, with a male-to-female ratio of 1:1 to 4:1. No statistical difference in racial distributions has been found. EtiologyPfitzner first proposed that the coalitions were the result of incorporation of accessory ossicles into the adjacent normal tarsal bones. This theory received some support from various authors, including Slomann, Badgley,5 and Harris and Beath.6 Leboucq first proposed in 1890 that the failure of segmentation of primitive mesenchyme was the cause of tarsal coalitions. His theory was supported by Solger (1890), Dwight (1907), Trolle (1948), and Jack (1954).19 In 1955, Harris found evidence of mesenchymal coalitions in fetal cadavers, conclusively proving Leboucq's theory. Through the work of Leonard, Wray, Herndon, and others, it is believed today that tarsal coalition is inherited in an autosomal dominant fashion with high penetrance. PathophysiologyThe normal motion of the subtalar joint during walking involves both rotation and gliding. The axis of motion of the subtalar joint is defined as a line deviated 42º from the horizontal surface and 16º medially or internally rotated from a line extending from the center of the calcaneus to a point between the first and second metatarsals. During stance phase, the subtalar joint rotates from a position of 4º external-valgus to 6º internal-varus. This motion compensates for the horizontal external rotation of the tibia during this phase. When the internal rotation is restricted by the coalition, the tarsal joints have to compensate, with flattening of the foot and loss of longitudinal arch and a valgus appearance in the horizontal plane. This leads to an adaptive shortening of the peroneal tendons, reactive peroneal spasm, and so-called peroneal spastic flatfoot. Prolonged restriction of motion eventually may lead to posterior facet arthrosis of the subtalar joint. Another motion of the subtalar joint lost is the gliding motion demonstrated during foot dorsiflexion. Cineradiographic studies have demonstrated a hinge motion instead, with widening at the plantar aspect of the midtarsal joints, narrowing at the dorsal surfaces, and overriding of the navicular on the talar head at maximum dorsiflexion. The traction effect of the later motion on the ligaments and capsule of the talonavicular joint is thought to be the genesis of the talar beaking seen in many radiographs of tarsal coalition. The pain symptoms associated with tarsal coalitions may therefore be attributed to ligament sprain, peroneal muscle spasm, sinus tarsi irritation, subtalar joint irritation, and arthritic changes. The variability of the symptoms in different patients may be due to the variability of subtalar restriction of the different coalitions. The specific but different ages of presentation of different coalitions would then be due to the different ages at which coalitions ossify and thus restrict subtalar motion. ClinicalPatients with tarsal coalition usually present during the second decade of life, but presentations in adulthood have been documented. Complaints include mild pain deep in the subtalar joint and limitation of range of motion. The patient usually presents after some traumatic event such as an ankle sprain. Indeed, what seem to be repetitive sprains should raise suspicions of tarsal coalition. Often, the symptoms are relieved by rest and aggravated by prolonged or heavy activity. In cases of calcaneonavicular coalition, pain may be more superficial and originate from the area of the coalition in the sinus tarsi. Palpation may elicit pain at the calcaneonavicular junction laterally. In cases of talonavicular coalitions, the pain is usually more vague, but tenderness may be elicited with palpation of the middle facet region, just anterior to the medial malleolus. Different coalitions ossify at different ages, possibly explaining the difference in ages of presentation of different coalitions. Slight limitations of range of motion and mild valgus are thought to be possibly all that is present prior to ossification. Talonavicular coalitions begin to ossify in children aged 3-5 years; calcaneonavicular coalitions begin to ossify in children aged 8-12 years; and talocalcaneal ones begin to ossify in adolescents aged 12-16 years. Loss of subtalar motion and valgus position of the hindfoot become more apparent as the coalition ossifies, leading to the appearance of pes planus. Middle facet talocalcaneal coalitions are associated with the greatest loss of subtalar motion and are the most likely to generate valgus. This loss of subtalar motion may be evaluated with the heel-tip test, wherein the examiner supinates the foot of a standing patient by raising the medial border of the forefoot and keeping the heel and lateral border in contact with the floor. In patients with limited or decreased subtalar motion, compensatory external tibial rotation is decreased and the patella is not observed to rotate outward as in a persons without tarsal coalition. Other tests include toe standing and the Jack toe-raise test; both demonstrate the fixed nature of the pes planus and the loss of hindfoot inversion. Studies have shown that patients with neutral hindfeet have fewer symptoms; it is likely secondary to decreased peroneal shortening. Cases of hindfoot varus have been reported in the literature in conjunction with calcaneonavicular coalitions. Repeated sprains may actually mask loss of subtalar motion by allowing motion because of ligamentous laxity. Although peroneal spasticity has been attributed to tarsal coalitions in the older literature, its occurrence is actually relatively infrequent. Peroneal spasticity may be intermittent or continuous, varying with activity or stress of the ankle joint. Differential diagnoses of tarsal coalition include tumor, rheumatologic processes, and fractures about the subtalar joint. A case report even exists of a previously asymptomatic talocalcaneal coalition that presented as a painful fracture of the talar beak. Tarsal coalitions have been shown to present as other foot deformities, including cavovarus deformity and talipes equinovarus. Syndromes that may present with tarsal coalitions include fibular hemimelia, Nievergelt-Pearlman syndrome, and Apert syndrome. In the cases of associated limb deficiency at birth, tarsal coalitions may present in association with ball-and-socket ankles,20, 21, 22 which has been demonstrated to allow compensatory inversion and eversion. INDICATIONSSurgical treatment of tarsal coalitions is indicated in cases in which conservative treatment has failed and symptoms persist (see Treatment). RELEVANT ANATOMYSee Pathophysiology. CONTRAINDICATIONSCoalition resection is contraindicated when significant degenerative change is present in the joints adjacent to the coalition. Arthrodesis is preferable in such cases. Subtalar arthrodesis alone is contraindicated in cases of talocalcaneal coalitions in which midfoot joints show signs of degenerative change. Triple arthrodesis is indicated instead. Finally, in patients with multiple anomalies, individual resections are unlikely to establish a normal-appearing and a normal-functioning foot and should therefore not be pursued. WORKUPImaging Studies
Histologic FindingsThe tissue of a tarsal coalition may be osseous, cartilaginous, or fibrous. Histopathologic analysis of resected nonosseous coalitions has revealed no evidence of neural elements. This absence of nerve tissue argues against the abnormal coalition tissue acting as a primary pain generator. Microfractures and histologic signs of bone remodeling near a coalition's boundary with normal bone have been identified and are likely pain generators via periosteal nerve fibers. TREATMENTMedical therapyCalcaneonavicular coalitions Initial conservative treatment may include soft shoe inserts or a trial of walking cast immobilization. These treatments have been described in the literature to extend from 3-6 weeks each. Cast immobilization trials have been repeated once prior to surgery if the first attempt did not relieve symptoms. Immobilization must be with the hind foot in neutral and away from valgus. In most symptomatic calcaneonavicular coalitions, conservative treatment yielded poor results. Talonavicular coalition In contrast to calcaneonavicular coalitions, conservative treatment decreasing subtalar motion or stress has been found to have good results in cases of first presentation with no evidence of arthritic changes. Surgical therapyCalcaneonavicular coalitions Given the ease and relatively good results of surgical treatment, coalition resection prior to onset of arthritic changes has become more commonly indicated. The procedure as described by Badgley5 and Cowell27 and others includes an anterolateral approach over the coalition, resection of at least 1 cm of the coalition, resection of a block rather than wedge section, interposition of the head of the extensor digitorum brevis muscle, and avoidance of the talonavicular joint to prevent theoretical subluxation of the navicular over the talar head. Some modifications of the original technique include use of bone wax or electrocautery to treat the remaining surfaces after bar resection and tying the interposition sutures over the plantar fascia and under the skin rather than securing them with a button over the skin. Various long-term studies of this technique have shown excellent or good results in 77-100% of patients. Talonavicular coalition Surgical treatment for symptomatic talonavicular coalition traditionally has been triple arthrodesis. Resection of the middle-facet coalition was not very successful prior to the advent of CT secondary to poor visualization of the coalition. Such resections have become more popular and are indicated in cases in which conservative treatment has failed, visualization of the middle-facet coalition is good, and no evidence of arthritic changes is present. Talar beaking is no longer considered by many to be evidence of degenerative change. Comfort and Johnson found that there was an 80% success rate when the coalition involved one third or less of the total surface area of the subtalar joint on CT.28 Wilde et al found that a valgus greater than 16º and a coalition surface area greater than 50% of the posterior facet on CT were predictors of poor results after resection.29 Luhmann and Shoenecker found that although an association existed between poor results and a heel valgus of 21º or a coalition greater than 50% of the posterior facet, some patients still had good postoperative results.30 They therefore recommended that resection be tried as a first procedure and that patients be informed that they could still have a good result in cases in which the poor predictive factors are present. Various long-term studies have shown excellent, good, or improved rates of 80-100%. The resection is approached medially, distal to the medial malleolus. The middle facet is exposed by retraction of the flexor hallucis longus tendon. The prominent joint is resected with a rongeur, and fat is interposed. In cases in which a resection is not possible or desired, Mann and Baumgarten have proposed fusion of the subtalar joint only, instead of the traditional triple arthrodesis, reasoning that any motion saved in the midtarsal joints would maintain force transfer during motion, decreasing or slowing degenerative changes in adjacent joints.31 However, in cases in which degenerative changes are apparent, triple arthrodesis is indicated, as isolated subtalar fusion would only accelerate the changes in the midtarsal joints. In cases in which skeletal immaturity is present, a Grice-Green extra-articular arthrodesis may be indicated as an intermediate procedure. Postoperative detailsPostoperative treatment includes immobilization for 3 weeks in a non–weight-bearing cast followed by 3 weeks of partial immobilization with nonweightbearing ankle cast and range-of-motion exercises out of the cast. This is then followed by gradual advance to full weight bearing and range-of-motion exercises with physiotherapy. Bilateral procedures are staged to allow full recovery of the first foot prior to surgery of the second foot. Follow-upFor excellent patient education resources, visit eMedicine's Foot, Ankle, Knee, and Hip Center. Also, see eMedicine's patient education articles Ankle Sprain and Sprains and Strains. COMPLICATIONSInfections and wound complications are possible with surgical resection. As previously stated, in the event of a failure to resolve symptoms in cases treated with resection of the coalition, various arthrodeses are appropriate as salvage or next-step treatment. In the case of calcaneal navicular bar resection, violation of the talonavicular capsule may result in subluxation of the navicular on the talus, which may lead to abnormal motion of the midfoot and risk of pain and degenerative changes. In the case of talocalcaneal coalition resections, it was found that coalitions 50% or greater in surface area than the posterior facet had a tendency to yield a poor result. This would imply that accidental resection of the middle facet 50% or greater than the posterior facet may yield a poor result. OUTCOME AND PROGNOSISNonoperative treatment of patients with symptomatic tarsal coalitions has not been uniformly successful. As such, most long-term studies have focused on outcomes following surgical treatment. Proper patient selection is a prerequisite for optimal results. Patients with extensive or multiple coalitions typically undergo fusion procedures, and those with less extensive or isolated coalitions undergo resection and soft-tissue interposition of their coalitions. Talar beaking must be critically evaluated but is not necessarily a contraindication to tarsal coalition resection. The vast majority of calcaneonavicular coalitions can be resected with the expectation of successful long-term results. Resection of symptomatic talocalcaneal coalitions yields optimal results when the coalition involves approximately one third or less of the total joint surface. FUTURE AND CONTROVERSIESTarsal coalitions are relatively rare congenital abnormalities of the foot in which 2 or more of the tarsal bones are joined by bone, cartilage, or fibrous tissue. The true incidence is unknown, as most are asymptomatic. The most common are calcaneonavicular and talocalcaneal coalitions. More than half are bilateral. Clinically, patients present with a history of chronic pain with activity or stress after a traumatic injury or repetitive sprains. The condition is poorly visualized with the standard AP and lateral radiographs, but secondary signs such as the talar beak or the anteater-nose sign may suggest it. Axial and lateral views may offer better visualization. CT with coronal cuts is the criterion standard, particularly in evaluating talocalcaneal coalitions. Conservative treatment includes soft shoe inserts and walking-cast immobilization. Surgical treatment includes resection of the coalition before onset of degenerative changes and subtalar fusion in the case of talocalcaneal coalitions. Currently, it is not clear what should control the use of talocalcaneal coalition resection; the limiting factors of heel position and percentage of involvement do not consistently segregate good and bad outcomes. However, once global degenerative changes have begun, triple arthrodesis almost always is indicated. MULTIMEDIA
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