Proximal femoral focal deficiency (PFFD) is a rare, non-hereditary

Heredity

Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...

 birth defect

Congenital disorder

A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...

 that affects the pelvis

Pelvis

In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

, particularly the hip bone, and the proximal femur

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

. The disorder may affect one side or both, with the hip being deformed and the leg

Human leg

The human leg is the entire lower extremity or limb of the human body, including the foot, thigh and even the hip or gluteal region; however, the precise definition in human anatomy refers only to the section of the lower limb extending from the knee to the ankle.Legs are used for standing,...

 shortened.

It is commonly linked with the absence or shortening of a leg bone (fibular hemimelia) and the absence of a kneecap. Other linked birth defects include the dislocation or instability of the joint between the femur and the kneecap, a shortened tibia

Tibia

The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....

 or fibula, and foot deformities.

Classifications

There are typically four classes (or types) of PFFD, ranging from class A to class D, as detailed by Aitken http://gait.aidi.udel.edu/res695/homepage/pd_ortho/educate/clincase/pffd.htm.

Causes

The cause of PFFD is uncertain. Two hypotheses have been advanced. The theory of sclerotome subtraction posits injury to neural crest cells that are the precursors to sensory nerves at the level of L4 and L5. Histologic studies of a fetus with unilateral PFFD have prompted an alternative hypothesis that PFFD is caused by a defect in maturation of chondrocytes (cartilage cells) at the growth plate. In either hypothesis, the agent causing the injury is usually not known. Thalidomide

Thalidomide

Thalidomide was introduced as a sedative drug in the late 1950s that was typically used to cure morning sickness. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide, and it is introduced as an immunomodulatory agent used...

 is known to cause PFFD when the mother is exposed to it in the fifth or sixth week of pregnancy, and it is speculated that exposure to other toxin

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

s during pregnancy may also be a cause. Other etiologies that have been suggested, but not proven, include anoxia

Hypoxia (medical)

Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...

, ischemia

Ischemia

In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...

, radiation

Radiation

In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

, infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

, hormone

Hormone

A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...

s, and mechanical force. PFFD occurs sporadically, and does not appear to be hereditary.

Treatment

Depending on the severity of the deformities, the treatment may include the amputation

Amputation

Amputation is the removal of a body extremity by trauma, prolonged constriction, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventative surgery for...

 of the foot or part of the leg, lengthening of the femur, extension prosthesis, or custom shoe lifts. Amputation usually requires the use of prosthesis

Prosthesis

In medicine, a prosthesis, prosthetic, or prosthetic limb is an artificial device extension that replaces a missing body part. It is part of the field of biomechatronics, the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control...

. Another alternative is a rotation prosthisis.

In less severe cases, the use of an Ilizarov apparatus

Ilizarov apparatus

The Ilizarov apparatus is named after the orthopedic surgeon Gavriil Abramovich Ilizarov from the Soviet Union, who pioneered the technique. It is used in surgical procedures to lengthen or reshape limb bones; to treat complex and/or open bone fractures; and in cases of infected non-unions of bones...

 can be successful in conjunction with hip and knee surgeries (depending on the status of the femoral head/kneecap) to extend the femur length to normal ranges. This method of treatment can be problematic in that the Ilizarov might need to be applied both during early childhood (to keep the femur from being extremely short at the onset of growth) and after puberty (to match leg lengths after growth has ended). The clear benefit of this approach, however, is that no prosthetics are needed and at the conclusion of surgical procedures the patient will not be biologically or anatomically different from a person born without PFFD.

External links

• Proximal Femoral Focal Deficiency at the Pediatric Orthopedics department of the Alfred I. duPont Hospital for Children
  Alfred I. duPont Hospital for Children
  Alfred I. du Pont Hospital for Children is a pediatric hospital located in Wilmington, Delaware. It is controlled by the Nemours Foundation, a non-profit organization created by philanthropist Alfred I. du Pont in 1936 and dedicated to improving the health of children. It is also referred to as the...
  
  
• PFFD treatment using Ilizarov devices Photo and X-ray
• NPR Interview with the author of a memoir about growing up with PFFD