Correction of Congenital Hallux Varus Deformity Using Modified Farmer\'s Technique: A Case Series

Aim and background: Congenital hallux varus deformity is an uncommon entity. There are various reasons for the development of the deformity. It can be primary without any underlying pathology, secondary (preaxial polydactyly), or tertiary (dwarfism). The medial aspect of the great toe at the metatarsophalangeal (MTP) joint region is explored to address the tightness of the abductor hallucis and the joint capsule. After the soft tissue release, with or without osteotomy for correction of the deformity, there will be a resultant defect. Farmer's technique is a surgical procedure to correct hallux varus, where the defect on the medial aspect of the great toe is covered using the “skin-fat” flap raised from the first web. Case description: We report two children with hallux varus deformity associated with preaxial polydactyly. They were brought to us with difficulty in wearing closed shoes and for cosmesis. Radiographs were taken, and the MTP or varus angles were measured. Preoperative varus angles for our patients were 47.1° and 69.6°. Farmer's technique was used for soft tissue balancing after the correction of the deformity in both our cases. We used a modified technique; the great toe and second toe were not syndactylized. Results were analyzed using the Phelps and Grogan method. Good to excellent correction of the varus deformity with good cosmesis was attained. Postoperative varus angle measurement showed a correction of 39.4° and 52° in our cases. Conclusion: Farmer's technique is a good option to correct congenital hallux varus deformity and can be combined with bony procedures. The lax first web skin-fat flap covers the medial soft tissue defect. Clinical significance: Congenital hallux varus is a difficult condition to treat as the chance of recurrence is high. Farmer's technique shifts the redundant skin and soft tissue in the first web to the medial aspect of the great toe that lacks soft tissue. This prevents recurrence.