Orthotic treatment for unstable hip joints in children with congenital insensitivity to pain with anhidrosis: A case series with follow-up until skeletal maturity

Congenital insensitivity to pain with anhidrosis is an extremely rare disorder characterized by congenital generalized loss of pain and thermal sensation, decreased sweating, intellectual disability, and self-mutilating behavior. Skeletal complications can develop even after minor trauma or an unknown cause, and management is difficult and sometimes unsuccessful, leading to the development of Charcot joints. We report 3 patients whose hip instability was treated with a hip action brace (HAB) that allowed for free abduction but prevented adduction. In 2 patients, metal attachments were added to bilateral joint units to prevent the patient's hip joints from flexing over 90 degrees. The HAB was well tolerated by all patients, and no adverse effects, such as pressure ulcers, occurred during this treatment. Of the 6 hips with instability, 1 remained dislocated, and 5 were stabilized after several years of HAB application. However, 3 joints in 2 patients aged between 14 and 16 years were subluxated or dislocated, leading to joint destruction. The follow-up period from the application of HAB until the most recent visit ranged from 10 to 13 years, and all patients reached skeletal maturity. Our experience suggests that HAB treatment is effective in reducing hip instability and maintaining stability for at least several years in children with congenital insensitivity to pain with anhidrosis.