Children are commonly referred to an orthopaedic surgeon for evaluation and management of a flatfoot deformity. We performed a review of the recent literature regarding evaluation and management of pediatric flatfeet to discuss new findings and suggest areas where further research is needed.
We searched the PubMed database using the following terms: pediatric flatfoot, tarsal coalition, and congenital vertical talus (CVT). We reviewed only papers published in English from January 1, 2011 to December 31, 2014.
Eighty-five papers were found. The authors identified 19 of these papers as having contributed important new findings.
Flexible Flatfoot (FFF)
For a condition that has been determined to account for more consultations to pediatric orthopaedic clinics than any other, the pediatric FFF remains poorly defined, making the understanding, study, and treatment of the condition extremely difficult.
In a Cochrane Review, Evans and Rome1 scrutinized the literature on FFF in children in regard to the epidemiology, foot development, etiology and associated issues, diagnosis, nonsurgical management, and surgical interventions. They concluded that the very definition of a flatfoot is debatable. The available prevalence estimates are limited by variable sampling, assessment measures, and age groups and, therefore, result in disparate findings. The authors noted that the literature suggests that the FFF reduces with age, and that most affected children and adults are asymptomatic. Joint hypermobility and increased body weight may increase flatfoot prevalence, independently of age. Furthermore, the review suggested that the pediatric FFF is often unnecessarily treated, and that there is very little evidence for the efficacy of nonsurgical intervention to affect the shape of the foot or to influence potential long-term disability for children with FFF. The authors note that inexpensive, generic foot orthoses can provide good positional support and relieve symptoms in those feet with activity-related pain. Customized foot orthoses should be reserved for children with foot arthritis, unusual foot morphology, or unresponsive cases. There is no evidence that supports the use of surgical correction of the typically asymptomatic and FFF in children. Surgery is only indicated at the failure of thorough conservative management.
A related critical review article from the same institution2 confirmed that there is very little evidence for the effectiveness of nonsurgical intervention for pediatric FFF. All articles reviewed were assessed using the Quality Index score, which uses a structured checklist to access the validity of clinical trials. They found only 13 articles, among the 429 published between 1970 and 2011 on the efficacy of nonsurgical interventions for pediatric FFF, that met the criteria for quality evaluation; and the mean Quality Index score was only 35%. The authors listed a number of methodological limitations of the studies, including the lack of a control group, inconsistent methods of diagnosis, small sample sizes, variable recruitment ages, failure to use valid and reliable outcome measures, and dissimilar follow-up periods. In addition to addressing these shortcomings, the authors recommended that future research efforts include longer, prospective follow-up studies to allow identification of effective interventions.
Historically, several authors have reported a greater body mass index (BMI) in subjects with FFF. Tenenbaum et al3 looked at the relationship between FFF and BMI, body height, and sex in 825,964 generally healthy 16 to 19-year-old Israelis who presented to a military recruiting center for a mandatory comprehensive medical evaluation since 1998. Acknowledging that the diagnosis of mild and severe pes planus in their study was subjective, they found a greater prevalence of FFF in males than females. FFF was associated with increased BMI and shorter body height for all grades of severity and in both sexes.
Not all flatfeet are the same. Bourdet et al4 identified 4 patterns of pes planovalgus in a study of 65 standing AP and lateral foot radiographs in 35 children aged 7 to18 years who were diagnosed with idiopathic or neurological flatfoot. Subtalar pes planus is characterized by marked subtalar valgus and longitudinal sag predominantly at the talonavicular joint. Midtarsal pes planus has marked midtarsal abduction and sag predominantly at the cuneonavicular joint without subtalar valgus. Mixed pes planus, the most common pattern, combines subtalar valgus, midtarsal abduction, and sag at both the talonavicular and cuneonavicular joints. Pes planocavus manifests as sag of the medial arch and cavus deformity of the lateral arch. The authors concluded that their classification system is helpful for the accurate assessment of the site(s) of deformity that can be used to determine the best surgical technique for a symptomatic flatfoot, although they have not validated their treatment algorithm.
The technique of arthroereisis involves the insertion of a metallic or synthetic implant in the region of the sinus tarsi to correct alignment of the subtalar joint in children with FFF. As reported in the previously highlighted review by Evans and Rome,1 the indication for this procedure remains controversial.
De Pellegrin et al5 reported an uncontrolled, retrospective study of 732 subtalar extra-articular screw arthroereisis procedures performed in 485 children between the ages of 5 and 18 years. Only 11% of the patients reported pain preoperatively. The justification for surgery in this study seemed to be the foot shape itself, and the ease of performing the minimally invasive procedure. Of note is that 2% of the patients reported pain postoperatively. It is not clear from the manuscript how many of those patients had pain preoperatively.
Perhaps the most commonly used procedures to correct an intractably symptomatic FFF are the anterior and posterior calcaneal osteotomies. Moraleda et al6 compared the calcaneo-cuboid-cuneiform (triple C) osteotomies procedure that was developed at the authors’ institution, with the calcaneal lengthening osteotomy (CLO) for the treatment of symptomatic FFF. The study compared 30 feet (21 patients) in the triple C group to 33 feet (21 patients) in the CLO group. The average follow-up for the CLO group was nearly twice that of the triple C group (5.3 vs. 2.7 y). The necessary additional osseous and soft tissue procedures of the CLO (CC joint fixation, medial soft tissue reefing, peroneus brevis lengthening, tendo-Achilles lengthening) were only performed between 18% and 38% of the time. That said, the authors found no difference in subjective or objective clinical outcomes between the study groups, and the CLO group achieved significantly better alignment at the talonavicular joint than the triple C group. The authors acknowledged that CC joint subluxation could have been a surgical mistake instead of a fault of the CLO technique and that the subluxation did not affect the outcome.
A tarsal coalition is often the cause of foot pain in children and adolescents who present with a rigid flatfoot deformity. Talocalcaneal (TC) and calcaneonavicular (CN) are the most common types. These patients are typically asymptomatic in early childhood, and generally present with activity-related hindfoot and midfoot pain in early adolescence. When the patient is not responsive to nonoperative treatment, surgery may be considered.
The long-term outcome of surgically resected coalitions is not well established in the literature. Outcomes are thought to vary with the type and extent of the bar as well as the amount of subtalar valgus deformity present. Mahan et al7 mailed outcome questionnaires to patients who had undergone surgical excision of a tarsal coalition. Sixty-three of 101 patients (63.4%) responded at an average of 4.6 years after surgery. TC coalitions were present in 20 patients; CN coalitions were present in the other 43 patients. Five patients (5%) required additional surgery after initial coalition resection. No limitation of activity due to foot pain was reported by 46 patients (73%). The authors found no difference in the self-reported outcomes between those treated for a TC and those treated for a CN coalition. As well, in patients with TC coalitions there was no difference in outcomes between those with <50% of the posterior facet involved compared with those where >50% was involved.
Longer term follow-up was reported by Khoshbin et al8 who retrospectively evaluated 32 tarsal coalition resections in 24 patients using clinical examination and self-reported functional outcome questionnaires. Concomitant calcaneal osteotomies were performed in 2 feet. The patients were followed for a mean of 14.4 years after surgery. The authors reported that the patients had little pain and few functional limitations. Patients with resected CN and TC coalitions reported similar function and pain on self-reported outcome questionnaires. In contrast to earlier studies, excellent long-term functional outcomes were found in patients who had TC coalitions involving greater than 50% of the posterior facet. As well, patients in the TC group with >16 degrees of hindfoot valgus and those with <16 degrees had similar outcomes scores.
As a tarsal coalition can sometimes be cartilaginous or fibrous, plain radiographs and computed tomography (CT) may not always be definitive. Guignand et al9 described a series of 19 feet with a CN coalition in 14 children. The authors reported that plain radiographs were not conclusive in 10 feet (53%), and these patients underwent further imaging including either bone scan, CT, or magnetic resonance imaging (MRI). The authors claimed that bone scan missed the diagnosis in 3 of 7 feet; CT missed the diagnosis in 4 of 11 feet. Twelve feet were assessed by MRI that confirmed the diagnosis in all instances. The authors concluded that MRI was the most effective imaging modality to assess CN coalitions.
A C-sign of Lateur may be present on a lateral radiograph of the foot in patients who have a TC coalition. The C-sign is formed by the medial outline of the talar dome, and the posteroinferior outline of the sustentaculum tali (Fig. 1). This line may seem continuous or interrupted. Moraleda et al10 performed a retrospective review of lateral radiographs of 88 feet in patients with a TC coalition confirmed by CT scan, and 260 patients with FFF. The authors found that a “true” C-sign (defined as complete, or having a linear interruption with rarefaction of the edges) had a prevalence of 41% in cases of TC coalition versus only 0.4% of flatfeet. They concluded that a “true” C-sign indicates the presence of a coalition, whereas the other types of interrupted C-signs were much more likely to be related to flatfoot deformity than to a coalition.
Assessing the adequacy of a TC coalition resection while in the operating room can be difficult. Kemppainen et al11 compared coalition resection in 14 feet using intraoperative CT scan with 12 feet in which this imaging modality was not used. The quality of resection was determined by 2 pediatric orthopaedic surgeons, who were blinded as to how the coalition resection was performed, by comparing preoperative and postoperative CT scans. The resection quality was deemed better in the intraoperative CT group. As well, the use of intraoperative CT altered surgical decision making in 3 feet (21%). Both groups showed similar improvement in pain at last follow-up. Larger, prospective studies would be useful to show whether improved clinical outcomes can justify the increased cost and radiation exposure using this imaging modality.
Mosca and Bevan12 retrospectively evaluated 13 painful TC coalitions in 8 patients who had undergone a CLO with gastrocnemius or Achilles tendon lengthening for correction of deformity with or without resection of the coalition. Five patients underwent isolated CLO due to large coalitions averaging 89% of the posterior facet. One patient with bilateral large coalitions underwent concomitant coalition resection and CLO. Two other patients had undergone earlier coalition resection and underwent CLO later when pain recurred. The clinical outcome scores improved in all cases. The authors concluded that restoring the hindfoot alignment can improve symptoms in cases of resectable as well as nonresectable TC coalitions with preoperative hindfoot valgus >16 degrees, and that resection of the coalition is not mandatory to have good results with CLO.
Less invasive methods of coalition resection have been proposed, including percutaneous and arthroscopic resection techniques. El Shazly and Abou El Ela13 used a percutaneous method to resect CN coalitions involving 12 feet in 9 patients. Under C-arm guidance, they used a 4.5-cannulated drill bit followed by a burr to resect the bar, followed by placing a rolled Teflon sheet as interposition material. The patients were followed for a mean of 26.4 months, and showed improved functional outcome. The authors reported no complications or recurrences at latest evaluation. Knorr et al14 reported arthroscopic resection of CN coalitions in 3 children. Two portals were established, a viewing portal that is posterior to the anterolateral process of the calcaneus and dorsal to the angle of Gissane, and a working portal distal to the calcaneal process and lateral to the extensor digitorum longus. They did not clearly state whether any interposition material was used. Clinical outcome scores for the 3 patients improved from 58 to 91, and there were no recurrences at 1 year. Quicker recovery and a smaller scar are cited as advantages.
Congenital Vertical Talus
A CVT is a rigid flatfoot deformity that presents at birth that is characterized by a fixed dorsal dislocation of the navicular on the head of the talus. Traditionally, this deformity was managed by cast applications followed by extensive soft tissue release. More recently, minimally invasive approaches, known as the “Reverse Ponseti” or “Dobbs” technique, have been described (Fig. 2).
Open Surgical Treatment
Ramanoudjame et al15 evaluated the results of midtarsal release and open reduction to manage 22 patients with 31 CVT followed for a mean of 11 years (range, 2 to 21 y). In 9 patients (15 feet) the deformity was isolated. Surgery was performed at a mean age of 33 months (range, 10 to 120 mo). The patients generally showed good functional results. The authors noted that subtalar motion was reduced, and the medial longitudinal arch was flat in every case. However, all patients were able to wear ordinary shoes. Only 6 feet (19%) showed persistent talonavicular subluxation. Five feet (16%) required further surgery. No talar avascular necrosis was seen. This article suggests that surgical management, which may be needed in older patients with CVT or those patients who fail minimally invasive approaches, may yield acceptable results with fewer complications than have been reported in the past.
Cast and Minimally Invasive Surgical Treatment
Chalayon et al16 reported management of 15 patients (25 feet) with nonisolated CVT (associated with spina bifida, distal arthrogryposis, and other genetic disorders) who were followed for a minimum of 2 years. The feet underwent an average of 5 manipulations and casts. Talonavicular pinning was performed through a small incision in the talonavicular joint in 5 feet. Selective capsulotomies of the talonavicular joint and anterior subtalar joint were performed in 20 feet. All patients had a percutaneous Achilles tenotomy. Relapse was noted in 5 feet (20%) that required further treatment. No subtalar stiffness was noted at latest follow-up evaluation.
Wright and colleagues17 reported management of 13 patients (21 feet) with CVT who were followed for a mean of 36 months (range, 8 to 57 mo). Six of the patients (9 feet) had teratologic CVT. They reported a median of 8 manipulations and casts to adequately improve the alignment of the talonavicular joint. In 7 feet (33%) a limited capsulotomy was needed to achieve final reduction. Initial correction was obtained in all. Overall, relapse was seen in 10 feet (48%): 4 of 12 feet (33%) in the idiopathic group. None of those with relapse had limited capsulotomy and open reduction. The authors postulated that including a limited capsulotomy at the initial operation may reduce the risk of relapse.
The upper age limit for successful management of CVT using techniques involving minimal surgery is not well established. Aslani et al18 treated 15 feet with CVT in 10 patients whose age ranged from 1 month to 9 years of age. Half of the patients had teratologic CVT. They used a minimally invasive approach that included serial manipulation and cast application, limited open reduction of the talonavicular joint, and Achilles tenotomy. After a mean of 2 years (18 to 36 mo) they reported pain-free, flexible, and plantigrade feet in all cases, including the feet of 4 patients aged 5 to 9 years. Although the follow-up was short, the authors suggested that older patients with CVT can be managed with a minimally invasive technique.
It is important to differentiate CVT from a marked FFF (oblique talus) because the treatment differs. Supakul et al19 suggested that there are limitations in interpreting plain radiographs of the foot in infants due to variable ossification patterns of the talus. They described the use of ultrasound to help differentiate CVT from flexible flatfeet in 13 infants below 6 months of age. On ultrasound, 10 feet were noted to have CVT confirmed at surgery. Advantages of this modality are that it directly depicts the cartilaginous talus and navicular and does not use ionizing radiation.
The pediatric FFF remains poorly defined, making the understanding, study, and treatment of the condition extremely difficult. Pediatric FFF is often unnecessarily treated, and there is very little evidence that nonsurgical intervention can affect the shape of the foot or influence the potential long-term disability.
The treatment of tarsal coalition remains challenging, but short-term and intermediate-term outcome studies show promising results of surgical resection. Longer term outcome studies are needed to help confirm these findings. Management of the associated flatfoot deformity may be as important as management of the coalition itself.
The management of CVT is still evolving; however, early results of less invasive treatment methods seem promising. Because these techniques are relatively new, we must await the appearance of longer term outcome studies.
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