Kirner's deformity of little finger

A 13-year-old boy presented with a history of swelling and increasing deformity of the distal phalanx of both little fingers. The parents had noticed a painless, progressive deformity of both little fingers over the past year. There was no associated disability. There was no history of trauma or infection. Physical examination revealed a symmetrical palmar and radial curving of the distal phalanges of the little fingers. There was no tenderness or signs of infection. The flexor and extensor mechanisms functioned normally (Fig. 1). X-rays were performed, which revealed a volar and radial curvature of the diaphysis of both distal phalanges; the epiphysis was thicker than normal, but normal in position (Fig. 2). The treatment options were discussed. Because the deformity was painless and epiphyses were open, continued observation was indicated. The patient will be followed periodically until skeletal maturity. In 1927, Kirner described a bilateral condition affecting the little finger, which was characterized by palmar and radial curvature of the distal phalanx associated with a variable degree of rotation. It is an unsightly deformity, which occurs infrequently, typically noted in children between the ages of 8 years and 10 years, and twice as commonly in females. Bilateral, symmetrical involvement is most common, although the right side is occasionally more severely involved. Although it can be progressive, rarely is it painful. Sporadic and familial occurrences have been reported, but there is no known specific causative factor. In cases of familial occurrences, inheritance has been described as an autosomal dominant trait with incomplete penetrance. No specific genetic linkage has been identified. A similar deformity may result from frostbite, physeal fracture and infection. Frostbite typically involves other fingers, while trauma and infection can usually be excluded by history. Kirner’s