Evans and Cotton Osteotomies Using Porous Titanium Wedges to Correct Pediatric Flatfoot Deformity.

Abstract

Background: The present video article demonstrates the use of Evans and Cotton osteotomies with porous titanium wedges for the treatment of pediatric flatfoot. Pediatric flatfoot is not commonly painful or disabling and usually resolves as the arch elevates spontaneously. However, in cases of flatfoot that persist despite nonoperative treatment, symptoms such as severe activity-related pain and medial foot calluses are an indication for surgical intervention³. The aims of treatment in pediatric patients are to correct anatomical deformity and reduce pain while maintaining mobility.

Description: Reconstruction of the foot is achieved by performing a lateral column lengthening calcaneal osteotomy (i.e., Evans osteotomy)⁴ and an opening-wedge medial cuneiform osteotomy (i.e., Cotton osteotomy)⁵. These procedures are preceded by assessment of the Achilles tendon with use of the Silfverskiöld test for contracture, and subsequent percutaneous lengthening if appropriate. The Evans osteotomy is performed by first accessing the lateral hindfoot via an Ollier incision, exposing the calcaneocuboid joint. Osteotomy of the anterior calcaneus is followed by distraction until the desired correction is achieved. Insertion of a porous titanium wedge, sized appropriately, supports the correction. To perform the Cotton osteotomy, an incision is made dorsally for access to the medial cuneiform. Image intensifier radiography is utilized to identify the middle of the medial cuneiform in both the coronal and sagittal planes in order to guide the osteotomy location. The osteotomy is opened with use of a Hintermann retractor, and an appropriately sized porous titanium wedge is inserted. Positioning of the wedges and subsequent deformity correction are evaluated with use of image intensifier radiography.

Alternatives: Numerous other surgical techniques have been described for the treatment of flatfeet^3,6. Extra-articular subtalar arthrodesis procedures have been frequently utilized^7,8, particularly in patients with substantial subtalar osteoarthritis. This procedure aims to stabilize the subtalar joint through fusion; however, arthrodesis is not frequently performed in pediatric patients because arthritis is less common and preservation of movement is important during growth. Arthroereisis similarly stabilizes the subtalar joint by limiting anterior movement of the talus with use of a prosthesis, rather than completely fusing the joint⁹. This can also be performed via a more minimally invasive technique. Other techniques have also been utilized to maintain osteotomy correction, including autologous iliac crest grafting and locking plates, both of which have their own limitations.

Rationale: The combination of Evans and Cotton osteotomies ensures restoration of the functional integrity of the medial longitudinal arch through lengthening of the lateral column, resulting in correction of forefoot abduction and hindfoot valgus while adjunctively plantar flexing the medial column. The combined use of these osteotomies demonstrates greater preservation of mobility compared with both subtalar arthrodesis and arthroereisis. Studies have shown good results over long-term follow-up^10,11, especially when combined with percutaneous Achilles tendon lengthening as appropriate^12,13. Autologous iliac crest grafting has been associated with persistent donor-site pain and morbidity¹⁴. Locking plates have been utilized to avoid the issues associated with autologous graft while also better maintaining correction in the long term; however, locking plates are associated with a longer operative time, screw breakage, and tendinitis as a result of rubbing over the plate¹⁵. Porous titanium wedges offer an effective method of maintaining correction, with significant radiographic, clinical, and symptomatic improvement in follow-up studies^16,17.

Expected outcomes: The long-term expectation is that correction of the deformity will reduce pain while restoring function of the subtalar joint. Studies assessing the use of titanium wedges for Cotton and Evans osteotomies have shown both good improvement in radiographic features and improvement of pain. With Evans osteotomies, pain (measured with use of a visual analogue scale) improved from 5.45 to 2.43 postoperatively, and postoperative Foot and Ankle Ability Measure Activities of Daily Living and Sports scores improved to 80.45 and 58.5². Similar results have been seen with Cotton osteotomies, with significant improvements in pain and radiographic findings (Kite angle and Meary angle) postoperatively¹. The overall complication rate has been reported at 15.2%, with major complications (nonunion with or without reoperation, deep infection, and chronic regional pain syndrome) at 2.1%. Minor complications reported included transient painful hardware, transfer pain, sinus tarsi syndrome, lateral column overload, lateral ankle pain, development of adjacent joint arthritis, and superficial wound complications².

Important tips: Rule out tarsal coalition with use of preoperative MRI. If present, resection can be performed and combined with Evans and Cotton osteotomies either at the same time or as a staged procedure.Careful dissection is paramount in order to avoid damaging the sural nerve while approaching the calcaneocuboid joint.Avoid "overstuffing" by ensuring appropriate sizing of the wedge.Take care to perform a good skin closure because lateral column lengthening always "tenses" the lateral foot.

Acronyms and abbreviations: LCL = lateral column lengtheningCCJ = calcaneocuboid jointII = image intensifierAP = anteroposteriorMRI = magnetic resonance imagingK-wire = Kirschner wireTA = tendon AchillesCT = computed tomography.