Spontaneous extrusion of a distally migrated Küntscher intramedullary nail from the left femur through a sinus over the knee joint

Migration of femoral Küntscher intramedullary nail (K-nail) proximally or distally within the femoral medullary cavity is a well-known documented complication, but spontaneous extrusion of a distally migrated K-nail through a sinus is a complication which has not been previously reported in the literature. This is the case report of a 32-year-old woman who presented with spontaneous extrusion of a Küntscher nail 6 years postinsertion. The underlying etiology and pathogenesis of the extrusion is subject to controversy and speculation. Infection and delayed union with shortening are etiological possibilities. Faulty selection of K-nail size: Loose fitting nail, disuse osteoporosis, and premature weight bearing may also be contributory factors.