Calcaneal lengthening osteotomy for treatment of idiopathic flexible flat foot in children

INTRODUCTION

The term flat foot defined as a deformity composed of flattening of ‎the medial ‎arch of the foot with heel valgus either in pediatric, adolescent ‎or adults. The ‎deformity may be rigid, which commonly congenital, or ‎flexible which is usually ‎acquired.¹ The pathology of flatfoot may be ‎an isolated pathology or a part from a ‎disorder like neurologic and ‎muscular diseases (as poliomyelitis, cerebral ‎palsy, ‎myelomeningocele), ‎generalized ligamentous laxity, genetic or collagen ‎disorders.² The ‎mean complaints of the patients are pain accompanied by ‎skin ‎ulcerations, ‎difficult shoe wear and serious problems in walking. The ‎galls of ‎treatment was utilized to solve this previous problems.^3-5 After failure of ‎conservative methods to solve the problem, surgical ‎methods are indicated.

The ‎advantages of surgical procedures are ‎restoring the foot alignment, relieving pain and ‎skin. Surgical procedures ‎in flexible flat foot vary from soft tissue to bony ‎osteotomies, ‎extra-‎articular arthrodesis of the subtalar joint, and triple arthrodesis.^2,3,6,7 Arthrodesis is largely discouraged in children because of ‎the ‎problems ‎associated with these techniques.^6-9 One of the effective ‎techniques is ‎the calcaneal lengthening osteotomy. Evans in 1975 is ‎the first to describe ‎and ‎modified by Mosca in 1995.‎^6,10 In this prospective the clinical and radiological results of eighteen ‎patients with ‎flexible flat foot (FFF) treated using modified Evans ‎calcaneal osteotomy technique ‎were evaluated in a mean follow up of 24 ‎months (range 18-36).‎

METHODS

Through the period from June 2010 to June 2013, eighteen feet in 12 ‎patients ‎were presented by FFF. Six patients were operated on for both ‎sides, the right side ‎was operated in 4 patients and left in 2 patients. ‎There were 8 males, and 4 females. ‎Calcaneal lengthening operation was ‎performed using modified Evans ‎osteotomy ‎technique in all feet. The ‎mean age at time of operation was 8.5 years (range 4 .5-11 years). ‎The mean ‎duration of follow-up was 24 months (range ‎18-42 months). The mean ‎age ‎at the end of ‎follow-up was 12.5 years (range 7.5-14.5 years). In ‎bilateral cases the ‎operation was done in two stages with 6 months ‎interval. All cases were idiopatic in ‎etiology. All ‎patients received ‎conservative treatment as orthosis and before the ‎operation.‎

Surgical technique

All operations were done under general anesthesia in supine ‎position and under ‎pneumatic ‎tourniquet. Over the sinus ‎tarsi, a lateral ‎longitudinal incision from 3-4 cm. ‎With careful dissection the ‎inferior ‎extensor retinaculum was incised from the ‎superolateral ‎calcaneal border. Special care was carried out to preserve the sural ‎nerve ‎and peroneal nerve superficial branches. Next step was elevation of ‎fleshy fibers ‎of extensor ‎digitorum brevis and the contents of sinus tarsi. ‎The tendons of peroneus ‎longus and brevis were released to be easily ‎retracted.

Under image intensifier the ‎calcaneocuboid joint was identified ‎and the site of osteotomy was determined ‎between the medial and ‎anterior facets of the calcaneus was ‎identified. After release ‎of the ‎periosteum over the calcaneus the osteotomy began from about 1.5 cm ‎proximal ‎to the ‎calcaneocuboid joint and directed obliquely ‎from ‎proximal laterally to distal ‎medially. This obliquity was done to ‎correct the valgus and distraction for lengthening ‎of the lateral column. ‎While using a laminar spreader to open the osteotomy site, the ‎size of ‎the graft was measured and the trapezoidal tricortical graft was ‎harvested from ‎the iliac crest through a separate incision. The reduction ‎of the ‎talo-navicular and ‎subtalar joints was evaluated clinically and ‎radiologically before any fixation.

The ‎graft is impacted from lateral to ‎medial while distracting to open the osteotomy site. ‎Two K- wires were ‎used, one to fix lateral column through calcaneocuboid, and the ‎other ‎through the talo-navicular to fix the medial column. The K- wires were ‎bended ‎long outside the skin for ‎easy removal after healing. A long ‎leg ‎cast was applied after ‎skin closure for 2 weeks postoperative. After ‎removal of stitches by 2 weeks the cast ‎was changed for another 4 ‎weeks. The K- wires were ‎removed after 6 weeks ‎postoperative in ‎outpatient clinic and a walking cast was applied for 4 weeks. For ‎clinical ‎evaluation a modified point scoring system containing 32 points for patients' ‎assessment. ‎When added 4 points for radiological evaluation the total of score became ‎36 points ‎as given in Table 1.

The patients have 30-36 points are of excellent results, 25-29 ‎points for good, ‎20-24 for fair, and less than 20 points for poor results. Collectively, ‎the excellent and ‎good results were classified as satisfactory and fair and poor results ‎were classified as ‎unsatisfactory.‎ For radiological evaluation, the postoperative films (anteroposterior and lateral weight-‎bearing radiographs of the foot) were compared to the preoperative films for each ‎patient ‎measuring the angles used for assessment of the deformity and correction ‎which are: the ‎talohorizontal (TH), talometatarsal (TMT), calcaneal pich (CP) and ‎talocalcaneal (TC) ‎angles in lateral view and TMT and TC angles in anterioposterior ‎view as in Table 2.

RESULTS

Clinically as given in Table 2 the modified points scoring system the results were ‎satisfactory in 16 feet (88.9%) and unsatisfactory in two feet (11.1%) at the final ‎follow up. As regards the pain, 14 feet (77.7%) were asymptomatic and 4 feet (22.3 %) had occasional pain during activity. There was collapse of the medial arch in ‎2 feet (11.1%). Heel posture was mild varus in 3 feet (16.6%), moderate valgus in one ‎foot (5.5%). Talar head prominence was mild in 3 feet (16.5%). The range of motion ‎of ankle joint was (93%) of normal in 15 feet (83.5%), and 88% of normal in three ‎feet (16.5%). Range of motion of subtalar joints was limited by 30% of normal in 6 ‎feet (33.3%), and in 12 feet the limitation was less than 15% from normal (23%). ‎Radiologically as shown in Table 2 and 3 all osteotomies were united within a mean time of 11 months (range 9-14 ‎months). All 6 angles were measured at the end of the follow up and assessed as ‎points added to the 32 points score.

TMT- Tarsometatarsal angle; TH- Talo horizontal angle; CP- Calcaneal pitch angle, TC- Talocalcaneal angle.

The score in 14 feet (77.7%) were (4) having the 6 ‎angels within normal values. The values from 4 angles were within normal values and ‎take score 3 in 3 feet (16.5%). In one foot (5.5%), 3 angles felt in normal range with ‎score 2.

DISCUSSION

‎Flexible flat foot (FFF) is a deformity represented with supination of forefoot ‎in relation to hind foot, shorter lateral column to the medial column, inappropriate ‎talo-navicular joint alignment as seen in Figure 2.

Many treatment options are utilized and vary from ‎simple orthosis to ‎triple arthrodesis.^1,3,11 When conservative methods failed ‎to control pain and shoe wear the surgical treatment is indicated. Many options like ‎soft tissue procedures, calcaneal osteotomy, ‎subtalar and triple arthrodesis. These ‎techniques have short term good results. Calcaneal ‎displacement osteotomies are ‎success-fully correcting hind foot valgus but insufficient for severe ‎cases. The limited ‎arthrodesis is widely reviewed in the literature and correction without arthrodesis is ‎better in long term results.^12,13

‎In this study ‎ the results of calcaneal lengthening osteotomy in 18 feet of 12 ‎patients with ‎idiopathic FFF deformity are evaluated. The ‎ hind and mid-foot were ‎clinically corrected in all cases with reformation of medial longitudinal arc. The ‎recommendation of Evans ‎is that the ideal age group for this technique was between 8 ‎and 12 years old. The ‎mean age of our patients at time of operation was 8.5 years (range 4.5-11 years). Evans ‎claimed that full correction cannot achieved with this ‎technique especially in the patients with ‎polio-myelitis. In our study the aetiology in all ‎cases was idiopathic deformity. The amount of correction is related to the size of the ‎graft. In this study, the correction position was obtained and stabilized with K-wire ‎fixation until union. Intraoperative radiology was used to assess the correction before ‎fixation in all cases.‎

‎Davitt et al evaluated plantar pressure contribution and ‎contact surface after ‎calcaneal lengthening operation in children and adolescents and ‎certifying the clinical ‎correction they showed that contact surface in both hind foot ‎and forefoot and ‎maximum mean pressure decreased in the medial side but increased ‎in the lateral side ‎and also that medial longitudinal arc was formed with all of the ‎plantar pressure ‎parameters that they have used.¹⁴

Ragab et al in a cadaveric study, they claimed that calcaneal ‎lengthening ‎osteotomy was an effective method for correction of FFF deformity ‎in short term ‎results, but they did not report on long term results.¹⁵ ‎

Phillips’ in 1983 reviewed the cases that were operated by Phillips.¹⁶ The results ‎were good in 15, fair in 3 and poor in 3 patients, but ‎their evaluation of cases was ‎based on the subjective parameters like clinical appearance, patient satisfaction, and relief ‎of ‎symptoms. The radiological evaluation did not use the angular ‎parameters for ‎correction, but classified ‎as complete correction and acceptable partial correction. ‎They reported that poor results in 3 cases were due to progressive deformities with ‎aetiologies ‎but there was no information about these aetiologies.‎

Yoo et al evaluated 92 feet of 69 cases and classified the clinical results by ‎assessing pain improvement, and callus.¹⁷ They reported the reformation of ‎medial ‎longi-tudinal arc, correction of the forefoot abduction and hind foot valgus. ‎They evaluated standing lateral radio-graphies, and the results were poor when the ‎talo-calcaneal ‎angle is less than 35 degrees, talus-first metatarsal angle was greater than ‎25 degrees ‎and calcaneal slope angle was less than 5 degrees. ‎

‎In this work, clinical ‎evaluation was made according to a modified point scoring ‎system containing 32 points for patients' assessment, and added 4 points for ‎radiological evaluation to get a total of score of 36 points ‎as shown in Table 1. For radiological ‎evaluation, we used the ‎talohorizontal (TH), talometatarsal (TMT), calcaneal pich (CP) ‎and talocalcaneal (TC) ‎angles in lateral view and TMT and TC angles in ‎anteroposterior view as in Table 2. The overall results were satisfactory in 16 feet (88.9%) ‎and unsatisfactory in two feet (11.1%) at the final follow up. 14 feet (77.7 %) were ‎asymptomatic and 4 feet (22.3%) had occasional pain during activity. There was ‎collapse of the medial arch in 2 feet (11.1%). mild heel varus in 3 feet (16.6%), ‎moderate valgus in one foot (5.5%). Talar head prominence was mild in 3 feet (16.5%). ‎

In this study we used the modifications of Mosca on skin incision, direction of ‎the ‎osteotomy, shape of the graft, application of internal fixation. Mosca [-] also used ‎allografts in 24 of 31 ‎patients and he reported no problems in osteotomy site bone ‎union. In all of our cases a tricortical autograft from iliac crest was used.

CONCLUSION

Calcaneal ‎lengthening osteotomy in symptomatic FFF is a successful technique and ‎can provide clinical and radiological correction of the deformity in hind foot and ‎forefoot. It is possible to gain complete reduction in the ‎flexible cases. The calcaneal ‎lengthening osteotomy is technically easy to be performed, with low ‎risk of ‎neurovascular injury. The limitation of the study is the short term follow up period as ‎the changes in subtalar joint may take a long time to occur. One of the advantages of ‎this technique is that other procedures can be performed later on unlike arthrodesis ‎which is a terminal operation.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the institutional ethics committee

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