Kirner’s deformity of the fifth finger: a case report

BACKGROUND: Kirner’s deformity is a rare bony deformity that is characterized by radial and volar curvature of the distal phalanx of the fifth finger. Affected patients usually present after the age of 5 years, with girls more affected than boys and bilateral involvement more common than unilateral. CASE PRESENTATION: We report a case of an eight-year-old girl who presented with progressive deformity of the right little finger. Radiographic evaluation revealed volar and radial curvature of the distal phalanx of the right fifth digit. Magnetic resonance imaging (MRI) further revealed the deformity along with widening of the physeal plate, lack of soft tissue enhancement and normal insertion of the flexor digitorum profundus tendon. The patient was followed conservatively for two years and is now being considered for corrective osteotomy. CONCLUSION: Kirner’s deformity is a rare abnormality of unknown etiology. Diagnosis is made with clinical examination and imaging evaluation. Clinicians should be aware of this uncommon deformity and differentiate it from other mimickers such as infection, physeal fracture, camptodactyly, and clinodactyly.