Current Concepts Review: Tarsal Coalition

Transcription

1 FOOT &ANKLE INTERNATIONAL Copyright 2006 by the American Orthopaedic Foot & Ankle Society, Inc. Current Concepts Review: Tarsal Coalition Frederick Lemley, M.D. 1 ; Gregory Berlet, M.D. 2 ; Keith Hill, M.D. 3 ; Terrance Philbin, D.O. 2 ; Brian Isaac, M.D. 4 ; Thomas Lee, M.D. 2 Columbus, OH INTRODUCTION A tarsal coalition occurs in approximately 1% of the population and often is an overlooked diagnosis when it presents in adults. Zuckerkand 1,55 published the initial description of a talocalcaneal coalition in Germany in Anderson 1 reported the presence of talonavicular coalitions in 1879, and Slomann 47 introduced the 45-degree lateral oblique view of the foot to diagnose calcaneonavicular coalitions in Slomann 47 also suggested the presence of an association between pes planus, hindfoot rigidity, and tarsal coalition. Badgley 3 associated calcaneonavicular coalition with peroneal spastic flatfoot in Later, Harris and Beath 22 linked peroneal spastic flatfoot with talocalcaneal coalition. Advancements in multiaxial imaging have enhanced our understanding of tarsal coalitions. Modern CT and MRI enable surgeons to characterize the extent of joint involvement, the composition and location of the coalition, and the degree of degenerative change of the affected and adjacent joints. This new information has influenced our clinical decision-making and treatment of tarsal coalitions. The purpose of this review is to discuss evidence-based recommendations for diagnosis, imaging, and treatment of tarsal coalitions in the pediatric and adult populations. ETIOLOGY A tarsal coalition is believed to result from a failure of embryonic mesenchymal differentiation and segmentation. 21,31 Its inheritance pattern is autosomal dominant with 1 Syracuse Orthopedic Specialists, Syracuse, NY 2 Orthopaedic Foot and Ankle Center, Columbus, OH 3 D.D.Eisenhower Army Medical Center, Fort Gordon, GA 4 Central Alberta Medical Imaging Services, Red Deer, Alberta, Canada Fig. 1: Frederick Lemley, M.D. variable penetrance. 32 Leonard 32 studied 31 patients with symptomatic coalitions and 98 of their first-degree relatives. Over 39% of these relatives demonstrated coalitions on radiographic evaluation; however, none were painful or had required treatment. Leonard 32 also observed that the location of the coalition, either talocalcaneal or calcaneonavicular, was not consistent along the familial lineage, suggesting a non specific expression of the involved gene. Corresponding Author: Gregory Berlet, M.D. Chief, Foot and Ankle, Department of Orthopedic Surgery, Ohio State University Orthopedic Foot and Ankle Center 6200 Cleveland Avenue, Suite 100 Columbus, OH gberlet@aol.com For information on prices and availability of reprints, call x226 PRESENTATION Talocalcaneal and calcaneonavicular are the most common coalitions. Talonavicular, calcaneocuboid, and other coalitions are rare and are not the focus of this review. Talocalcaneal and calcaneonavicular coalitions are bilateral approximately 1163

2 1164 LEMLEY ET AL. Foot & Ankle International/Vol. 27, No. 12/December 2006 Table 1: Level of Evidence and Grades of Recommendation Level of Evidence Level I: high quality prospective randomized clinical trial Level II: prospective comparative study Level III: retrospective case control study Level IV: case series Level V: expert opinion Grades of Recommendation (given to various treatment options based on Level of Evidence supporting that treatment) Grade A treatment options are supported by strong evidence (consistent with Level I or II studies) Grade B treatment options are supported by fair evidence (consistent with Level III or IV studies) Grade C treatment options are supported by either conflicting or poor quality evidence (Level IV studies) Grade D when insufficient evidence exists to make a recommendation 50% to 60% of the time. 16,32,48 They usually present in childhood and early adolescence. Calcaneonavicular coalitions often present between 8 and 12 years of age. Talocalcaneal coalitions present at a later age. However, the typical pediatric or adolescent presentation is not always the case. Tarsal coalitions in adults may become symptomatic if awakened by trauma. 46 Both types of coalitions may be comprised primarily of cartilage (synchondrosis), fibrous tissue (syndesmosis), or bone (synostosis). The onset of symptoms corresponds to the ossification of the coalition, causing it to stiffen, cause pain, and alter the kinematics of the involved joint. A histopathologic analysis of 55 coalitions found no nerve fibers within the coalition. 28 The authors hypothesized that an incomplete or ossifying coalition became painful as a result of microfracturing at the coalition-bone interface. Another investigation also identified a causative relationship between progressive ossification and symptoms. 26 Typically, patients present with a history of an ankle or foot injury that is slow to resolve. Pain often is diffuse, but may be localized to the sinus tarsi with a calcaneonavicular coalition or deep within the subtalar joint in the case of a talocalcaneal coalition. Patients report difficulty walking on uneven ground and performing strenuous activities. A consistent finding on physical examination of patients with a tarsal coalition is diminished range of motion of the subtalar joint. Passive inversion and eversion are reduced and a test of single heel-raise demonstrates that the calcaneus remains in a valgus position. A comparison of motion with the contralateral foot may confirm this finding, except in the presence of bilateral coalitions. Talocalcaneal coalitions demonstrate more restriction of inversion and eversion of the subtalar joint. Observation of the patient while standing often reveals a valgus alignment of the hindfoot. A flatfoot deformity is most often associated with coalition, but cavovarus deformity may occur though much more infrequently. 49 The diagnosis of peroneal spastic foot was thought to be pathognomonic for coalition, although this can be caused by a myriad of conditions including rheumatoid arthritis, infection, osteoid osteoma, and hindfoot injuries. 4,37 Peroneal spastic flatfoot is suggestive but not diagnostic of coalition. 11,37 IMAGING The diagnostic capabilities of imaging to detect tarsal coalitions continues to evolve; however, plain radiographs of the feet remain the first step in evaluation. Full-length, weightbearing anteroposterior and lateral radiographs of the foot may exhibit signs of a coalition. Lateral radiographs may reveal the anteater nose sign or the C sign. The anteater nose sign represents the extension of the anterior process of the calcaneus toward its junction with the navicular. This characteristic projection, most easily recognized when fully ossified, is diagnostic of calcaneonavicular coalition. 40 The C sign represents a continuous circular density formed by the outline of the talar dome and the inferior outline of the sustentaculum tali. However, the C sign also may represent abnormal morphology of the middle facet without a coalition. 30 Talar beaking at the talonavicular joint most commonly occurs in talocalcaneal coalition but also occurs in calcaneonavicular coalition. A 45-degree medial oblique view is useful for identifying calcaneonavicular coalitions. Several other signs have been described to detect coalition on plain films. Dysmorphic sustentaculum tali, loss of the normal middle facet, and shortening of the talar neck are all suggestive of a talocalcaneal coalition. 14 Altered navicular morphology and visualization of the coalition on the anteroposterior view may suggest calcaneonavicular coalition. 14 Radiographic diagnosis of talonavicular coalition often is less difficult than that of talocalcaneal coalition. Although several radiographic techniques for specifically imaging the middle facet have been described, radiography is being replaced by CT and MRI. Both are excellent for demonstrating coalitions unrecognized on plain films, 23,43 and they describe the size and location of the coalition more accurately. MRI helps differentiate the character of the coalition and the presence of arthrosis in surrounding joints. Radionuclide scanning has been used primarily as a screening tool rather than a diagnostic one, but technetium-99m bone-scanning including single-photon-emission tomography (SPECT) has been used to diagnose inflammatory arthrofibrosis of the middle facet in adolescents, 18 a condition that can cause symptoms similar to a true coalition.

3 Foot & Ankle International/Vol. 27, No. 12/December 2006 TARSAL COALITIONS 1165 TREATMENT Nonoperative Management Conservative treatment is the first-line recommendation for symptomatic talocalcaneal coalitions 9,13,17,22,23,25,36,39,46,52 (Grade B recommendation) and talonavicular coalitions 11,22,36,37,41,52 (Grade B recommendation). Leonard 32 demonstrated that most coalitions are asymptomatic, suggesting that a conservative trial may be effective in restoring a pain-free foot. Activity modification, medial heel wedge, arch supports, and UCBL orthoses may be of help in mildly symptomatic individuals. Boots or high-top shoes may be substituted if deemed more acceptable. If simple measures fail or pain is severe, 4 to 6 weeks of immobilization in a cast may help. If asymptomatic after cast removal, the patient may gradually resume full activity. If symptoms continue after exhaustive conservative measures, operative management may be required. Operative Management of Calcaneonavicular Coalition Operative treatment options for calcaneonavicular coalitions are excision and arthrodesis. Early studies recommended triple arthrodesis over excision. 3 Andreasen 2 suggested triple arthrodesis as the procedure of choice. Despite satisfactory results after resection in 22 of 30 patients at 4 to 13 year followup, Andreasen was concerned about progressive radiographic evidence of transverse tarsal joint arthrosis and a high rate of coalition recurrence. However, Mitchell and Gibson s 35 Level IV (Table 1) study suggested that resection produced successful outcomes: 31 of 41 feet in 10 to 14-year-old patients had satisfactory results after excision. Multiple Level IV studies thereafter supported excision of calcaneonavicular excisions in young patients. 20,24,25,38,50 Some Level IV evidence suggested that younger patients whose coalitions remained cartilaginous had better results, 20,25 and Jayakumar and Cowell 25 reported that an osseous coalition was a relative contraindication to resection because of the increased likelihood of arthritic changes in surrounding joints. Cowell 11 suggested that excision produced the best long-term results in patients under 14 years of age. However, 10 of 12 patients averaging 30 years of age at the time of excision reported subjective improvement in the case series of Cohen et al. 6 Based on the multiple level IV studies, excision appears to be the appropriate treatment for calcaneonavicular coalitions in young patients (Grade B recommendation). In appropriate candidates, good to excellent results can be expected more than 10 years after resection (Table 2). 20,24 Talar beaking was initially believed to represent early talonavicular arthrosis and to be a relative contraindication to excision. 24,35 Several Level IV evidence studies have suggested otherwise. 6,20,50 Swiontkowski et al. 50 suggested that the isolated talonavicular beak was indicative of a traction process occurring secondary to increased motion Table 2: Clinical studies of calcaneonavicular coalition resection Name Year Level of evidence Number of feet RX/outcome/key points Mitchell et al IV 41 Resection/no interposition, 27/41 complete pain relief, 67% bone recurrence, 4 13 y/o Andreasen IV 31 Resection/EDB interposition, 22/30 Satisfactory, y/o Cowell IV 26 Resection/EDB interposition, 23/26 good/excellent Chambers et al IV 31 Resection/EDB interposition, 29/29 satisfied, average 8 y/o Swiontkowski et al IV resection/interposition, 5 primary triples, 35/39 resection improved, average 12 y/o Inglis et al IV 16 Resection at 8 y/o, 11/16 good/excellent results at 23 year F/U Gonzalez et al IV 75 Resection/EDB interposition, 58/75 good to excellent, average 11 y/o Moyes et al IV resected/edb interposed, 9/10 no bar recurrence. 7 resected/no interposition, 3/7 bar recurrence Cohen et al IV 13 Resection/+/ EDB, 10/12 subjective improvement, average 33 y/o EDB = extensor digitorum brevis; y/o = years old; F/U = followup.

4 1166 LEMLEY ET AL. Foot & Ankle International/Vol. 27, No. 12/December 2006 Table 3: Clinical studies of talocalcaneal coalition resection Name Year Level of evidence Number of feet RX/outcome/key points Swiontkowski IV 14 4/5 asymptomatic after resection, 7/9 asymptomatic after primary arthrodesis Olney et al IV 10 Resection/fat interposition/bone wax, 8/10 good/excellent, average 14 y/o, average 42 mf/u Takakura et al IV 67 Resection, 31/33 good/excellent subtalar fusion, 3/3 good/excellent Kumar et al IV 18 Resection/fat, FHL, or bone wax, 16/18 good/excellent, average 14 y/o, average 4 y F/U Wilde et al IV 20 Resection/fat interposition, 10/20 good/excellent McCormack et al IV 9 Resection/fat interposition/bone wax, 8/9 good, average 11 y/o, 10y F/U Kitaoka et al IV 14 Resection/+/ interposition, 9/14 good/excellent results, average 17 y/o, 6y F/U Comfort et al IV 20 Resection, 15/20 good/excellent, average 14 y/o, average 29 m F/U Raikin et al IV 14 Resection/FHL interposition, 12/14 good/excellent, 9 16 y/o Westberry et al IV 12 Resection coalition and sustentaculum, 11/12 good/excellent, average 13 y/o, 5 y F/U Giannini et al IV 14 Resection/arthroereisis, 14/14 improved, average 14 y/o, 2-4 y F/U FHL = flexor hallucis longus; F/U = followup; y/o = years old; y = years; m = months. across the joint. Intraoperative inspection of the joint at the time of beak excision showed no degenerative change. Mosier and Asher 37 described the beak as a result of repeated minute elevations of the talonavicular capsule and periosteum. Cohen et al. 6 reported successful outcomes despite the fact that 54% of the feet undergoing excision showed evidence of talonavicular beaking. Gonzalez et al 20 found no correlation between the outcome of excision and the presence of a talonavicular beak in 75 feet. These Level IV studies suggest that talonavicular beaking is not a form of arthrosis and is not a contraindication to coalition excision. Classic radiographic evidence of degenerative change in the form of joint space narrowing and cyst formation in the tranverse tarsal or subtalar joint are contraindications to isolated coalition excision. Multiple Level IV studies have suggested triple arthrodesis as the procedure of choice (Grade B recommendation) in joints with these changes. 6,9,12,13,16,24,25,37,50 The available Level IV evidence regarding interposition after coalition resection is conflicting. Options include the extensor digitorum brevis (EDB) muscle, 2,10,20,21,38,50 bone wax applied to cancellous surfaces, 6 fat, 50 or nothing. 21,38 Moyes et al. 38 retrospectively reviewed 17 coalitions, 10 of which had resection followed by EDB interposition and seven had no resection with interposition material. Three of the feet without EDB interposition had recurrent bone formation and return of preoperative symptoms. The correlation proved statistically significant. Mitchell et al. 35 reported a 67% rate of recurrence of bone formation without any type of interposition. However, in 44 feet Swiontkowski et al. 50 reported no recurrence of bone formation in 44 feet after using either EDB or fat for interposition. Cohen et al. 6 reported wound dehiscence in three of six patients who had EDB transfer and bone wax application, although the patients were older than those in most coalition populations. Application of bone wax and gel foam produced results similar to those of EDB transfer without the added wound complications. The evidence is therefore conflicting in regard to interposition. Based on a high incidence of recurrent bone formation with no form of interposition, routine interposition seems warranted after calcaneo navicular resection (Grade B recommendation). However, conflicting evidence (Grade D) exists with regard to the particular type of interposition

5 Foot & Ankle International/Vol. 27, No. 12/December 2006 TARSAL COALITIONS 1167 material. Most Level IV studies have reported use of EDB interposition. Operative Management of Talocalcaneal Coalition The optimal operative management of talocalcaneal coalitions has yet to be conclusively determined. The primary operative options remain resection of the coalition and arthrodesis. Multiple factors have been described as important in predicting outcomes and directing the appropriate operative intervention: age of the patient, composition and size of the coalition, degree of hindfoot valgus, presence of talar beaking, and presence of degenerative change within adjacent and surrounding joints. The level of evidence in reference to each of these factors is universally Level IV with the small number of cases and the requisite retrospective study design (see Table 3). Several Level IV studies have suggested a correlation between increased hindfoot valgus and poorer outcomes after resection. Wilde et al. 54 found that more than 16 degrees of heel valgus correlated with a poorer outcome after resection. Luhmann et al. 33 found no significant correlation at 16 degrees, but found poorer outcomes with resection if more than 21 degrees of hindfoot valgus were present. However, Luhmann et al. 33 did not recommend abandoning coalition excision because several patients demonstrated good results despite more than 21 degrees of valgus. Based on Level V evidence, Luhmann et al. 33 recommended either a medializing calcaneal osteotomy or a lateral column lengthening. A medializing calcaneal osteotomy was recommended if subtalar motion was significantly reduced after the coalition excision. Otherwise, a lateral column lengthening was recommended. In another Level IV study, Giannini et al. 19 excised talocalcaneal coalitions in 14 adolescent feet and then corrected the residual valgus deformity with a bioabsorbable subtalar arthroereisis implant. Nearly 90% of patients had improvements in pain and motion, and 100% had improved hindfoot alignment. Patients younger than 14 years had better results. Giannini et al. 19 further recommended either arthrodesis or calcaneal osteotomy in skeletally mature patients. In related Level IV literature, Cain and Hyman 4 achieved relief of pain in 14 of 14 peroneal spastic flatfeet with closing wedge calcaneal osteotomy alone. Conversely, Davitt et al 15 demonstrated in a cadaver study that medial displacement calcaneal osteotomy caused a statistically significant shift of pressure anteriorly toward the middle facet. However, application of this data to clinically symptomatic coalition is lacking. Overall Level IV evidence suggests that results after resection seem to be poorer with increasing degrees of hindfoot valgus, although no threshold has been established. Level IV studies suggest excision of talocalcaneal coalitions despite hindfoot valgus (Grade B recommendation). However, poorer outcomes may be anticipated with greater degrees of hindfoot valgus based on level IV data. Insufficient evidence exists to support the ideal management of residual valgus after coalition excision Size also may play a factor in the outcome of resection of talocalcaneal coalitions based on level IV evidence. Scranton 16 was the first to suggest that coalitions larger than half of the entire subtalar joint should not be resected, although it appears this number was determined arbitrarily. Wilde et al. 54 found consistently unsatisfactory results after resection when the relative coalition area was larger than 50% of the posterior facet. Luhmann and Schoenecker 33 reported a statistically significant association between outcome and the area of the talocalcaneal coalition compared to the area of the posterior facet: coalitions larger than 50% of the posterior facet had poorer outcomes. This was not absolute because several patients with coalitions involving more than 50% of the joint had good to excellent results. Luhmann et al. 33 recommended excision despite the size of the coalition. Johnson and Comfort 8 found 75% fair or poor outcomes if the resected coalition represented more than one third of the total subtalar joint surface. Kumar et al. 29 suggested that resection of all coalitions regardless of extent of involvement of the middle facet produced satisfactory outcomes. However, they did not specifically quantify coalition size in respect to the posterior facet or the subtalar joint. Excision of larger coalitions is successful, but the excision of larger coalitions has a poorer prognosis than that of smaller coalitions (Grade B). A threshold size at which excision is contraindicated has not been determined The use of interposition material after talocalcaneal coalition excision has been debated in the literature. Level IV evidence suggests good to excellent results can be obtained using no interposition material at all, 27,29,34 bone wax, 53 fat graft, 24,27,29,33,39,45,46,54 bone wax and fat graft, 37 and a portion of the flexor hallicus longus tendon. 27,29,44 Coalitions have recurred, but no statistically significant evidence has been presented to suggest the interposition material as the problem. Westberry et al. 53 recommended excision of the entire sustentaculum to ensure complete removal of the coalition. They demonstrated good to excellent results without further progression of deformity despite removing the entire sustentaculum. Kumar 29 and Raikin et al. 44 reported excellent results with interposition of a portion of the flexor hallicus longus tendon. Neither tendon rupture nor loss of hallux interphalangeal motion was problematic. Kumar et al. 29 used bone wax, fat, or FHL in 18 feet and found no significant differences in outcomes. Scranton 46 and Salomao et al. 45 harvested local fat from behind the calcaneus through the same incision with good results. Fat grafts from other sites including the buttock have had similar success but with increased donor morbidity. Level IV evidence suggests that some form of interposition should be used (Grade B); however, the specific type of interposition is indeterminate Patient age also has been cited as a prognostic factor based on level IV evidence. Cowell 9,12,13 believed that degenerative

6 1168 LEMLEY ET AL. Foot & Ankle International/Vol. 27, No. 12/December 2006 change was inevitably present at the time of presentation, thus making age a significant factor in predicting outcome. He recommended conservative management first and triple arthrodesis if no relief was obtained. Giannini et al. 19 reported that patients younger than 14 years had better outcomes than older patients, although an arthroreisis implant was used routinely after coalition excision. Kitaoka et al. 27 performed gait analysis of 14 feet 6 years after resection and found residual functional deficits despite successful clinical results. They did not find an association between clinical outcome or functional deficit and the age of the patient. Several other Level IV studies found no association between age and prognosis. 8,29,33,39 Based on Level IV studies, age is an indeterminate predictor of success of coalition excision Level IV evidence also indicates that talar beaking with talocalcaneal coalition is not indicative of degenerative change as is also the case in calcaneonavicular coalitions. 27,37,50,54 The talar beak represents a traction spur caused by accommodative hinge-like motion through the transverse tarsal joints as described in the discussion of calcaneonavicular coalitions. 50 This spur is found routinely in the absence of other radiographic findings typically associated with degenerative change. Kitaoka et al., 27 in a Level IV study, found that five of six patients with talar beaking had excellent results after talocalcaneal coalition resection. Similarly, Wilde et al. 54 found no correlation between talar beaking and outcome. McCormack et al. 34 resected nine coalitions, several of which had talar beaking, and found satisfactory results with no radiographically evident arthritic progression in eight of nine patients at minimum 10-year followup. Talar beaking itself is not a sign of arthrosis, and is not a contraindication to talocalcaneal coalition excision (Grade B recommendation). The presence of advanced degenerative changes in the tarsal joints is a contraindication to isolated resection of the coalition based on Level IV evidence. Triple arthrodesis has been recognized as the traditional treatment for talocalcaneal coalition associated with degenerative change in surrounding joints. 9,46,50 Takakura et al. 51 performed isolated subtalar arthrodesis despite arthrosis in the transverse tarsal joints because of culturally specific needs to maintain some degree of hindfoot motion. Swiontkowski et al. 50 performed arthrodesis in nine patients with talocalcaneal coalitions, including four triple and three subtalar arthrodeses. All those with subtalar arthrodeses improved, but two of the four with triple arthrodeses deteriorated. This was attributed to poor technique as judged by the position of the midfoot and hindfoot. The available Level IV evidence supporting arthrodesis in the presence of degenerative change is conflicting (Grade D recommendation). The routine use of CT and MRI may help guide future recommendations. Salvage Talonavicular or calcaneonavicular coalition excision may be unsuccessful, and patients may continue to have persistent pain because of incomplete excision, recurrent bone formation, or arthritic changes in the surrounding joints. Level IV evidence suggests that triple arthrodesis has better outcomes than re-excision when recurrent bone formation causes pain. 6,24 Isolated subtalar fusion for failed calcaneonavicular or talocalcaneal coalition excison has been reported to be successful in very small retrospective case series. 6,50 Most Level IV evidence suggests that triple arthrodesis is the most reliable salvage operation for failed excision (Grade B recommendation). 2,6,7,12,20,33,37,50 SUMMARY The two most common types of tarsal coalitions are talocalcaneal and calcaneonavicular. Painful tarsal coalitions have an incidence of approximately 1%. However, because most coalitions are presumed asymptomatic, the true prevalence is unknown. Tarsal coalition is inherited in an autosomal dominant fashion with variable penetrance. The etiology is believed to be a failure of mesenchymal differentiation. The onset of pain at a coalition corresponds to the ossification of the coalition. Microfracture at the ossifying coalition-bone interface is a proposed source of pain. Advances in imaging capabilities with CT and MRI allow clinicians to characterize the size, character, and location of the coalition. In choosing between resection and arthrodesis, CT and MRI more accurately show the presence of arthrosis in surrounding joints. The initial treatment for a tarsal coalition is conservative. A medial heel wedge, arch support, UCBL, or cast is first-line treatment. Isolated talar beaking is not characteristic of degeneration of the joints of the hindfoot and, therefore, is not a contraindication to coalition resection. True degenerative change is an absolute indication for arthrodesis. Calcaneonavicular coalitions unresponsive to conservative treatment are best managed by coalition resection. Some form of interposition is recommended at the site of the resection; interpostion of EDB muscle belly is most commonly used. Talocalcaneal coalitions unresponsive to conservative treatment are best managed by coalition excision, although outcomes are not as good as those after excision of calcaneonavicular coalitions. Older age at presentation, larger extent of coalition, and increased hindfoot valgus may be predictive of poorer outcomes. Triple arthrodesis is the accepted form of salvage after failed excision of a tarsal coalition. REFERENCES 1. Anderson, RJ: The presence of an astragaloschaphoid bone in man. J. Anat. Physiol. 14: , 1879.

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