Introduction

This chapter is all about the how and why of PFFD. We'll learn some of the terminology and classifications used in PFFD.

Many people think of a an object that completely encloses a limb when they hear the term prosthesis, but prosthesis for PFFD individuals can mean any number of things. For example a large lift on a shoe, to a lift + ankle support device, to a hip/foot/leg device as in the [[Alternatives to Surgery in the Treatment of PFFD| Moseley Device]] to a cast-like object that covers the foot/leg/knee. Which to use will depend on the age of the person with PFFD, the hip, the knee, the tibia, the ankle and the foot, etc. E.g.

Limb lengthening used to only be possible in cases with lower grade PFFD (Aitken
class A). In 2004 the ability to lengthen other cases has gotten better - however - the maximum lengthening should not exceed 8-l2cm in older children and 4-6cm in younger children ². The presence of a stable hip, knee, and foot are also very important.

Leg lengthening can be a very painful, very long, process with multiple surgeries
and complications. At the Maryland Center for Limb Lengthening they reported a 70% complication rate with 50% of cases requiring additional surgery to treat complications. ² Before lengthening can begin, it is important to first stabilize the hip joint. Without this, they are at increased risk for dislocation of the hip joint during lengthening.

Treatment options for unilateral PFFD are based on 1) severity (length discrepancy, Aitken Class), and 2) presence or absence of a functional foot and ankle. A knowledge of the anticipated final leg-length discrepancy is probably the best guide to treatment options.^{[Hall, 1969]}

By the time a child is approximately 3 yrs of age, one should be in a position to predict leg-length difference.^{[Hall, 1969]} (Probably much sooner if the difference is great.)

Bilateral PFFD usually only requires prosthetic treatment. Children with bilateral PFFD can usually walk well on their own feet, and prostheses are only needed to bring them to the height of their peers. Surgery is not usually recommended because it would destroy the child's ability to walk without the prosthesis. Surgery would only be needed in cases with severe foot deformities that inhibit normal weight bearing.

Almost all bilateral PFFD cases are Aitken Class D (no acetabulum and no femoral head).

To search for others who have bilateral PFFD on the pffd.org site you can go to

A number of treatment options have been described over the years. Even now (2005) a uniformity of opinion does not exist. Unfortunately there have been no large-scale, long-term outcomes studies for PFFD. It has been frequently said that each case of PFFD is unique and needs to be treated on it's own merit. To a degree this is true, yet some basic principles do apply and help with the decision making.

Dr. Dror Paley is a doctor who specializes in lengthening reconstructive surgery (LRS) using the Ilizarov Technique. He wrote in his paper Lengthening Reconstruction Surgery for Congenital Femoral Deficiency

Classifications of congenital short femur and proximal femoral focal deficiency ( PFFD ) are descriptive but are not helpful in determining treatment....My classification system is based on the factors that influence the lengthening and reconstruction of the congenital short femur. ^{[[Lengthening Reconstruction Surgery for Congenital Femoral Deficiency|Dror]]}

His classification is based on the hip and knee structures.

Type 1: intact femur with mobile hip and knee
   a) normal ossification proximal femur
   b) delayed ossification proximal femur

Aitken Classifications

Class A

In Class A the head of the femur is present, together with an adequate acetabulum
(hip socket) and a very short femoral shaft. Initially, there is no bony
connection between the femoral shaft and the head of the femur. At skeletal
maturity a bony connection will be present between the femur head and shaft.
⁴

Class B

In Class B the acetabulum and head of the femur are present, but the femur
head may not be visible due to delayed ossification (formation of bone).
Based on the presence of the acetabulum, Dr King's theory can be used to
deduce that the femur head will develop. No bony connection exists between
the femoral shaft and head, and the upper end of the femoral shaft usually
has a small bony tuft. Unlike Class A, at skeletal maturity a bony connection
will not exist between the femur head and shaft. Studies show that the head
and shaft do not move together, and , therefore it is believed that there
is no cartilaginous connection between the shaft and head.⁴

Class C

Several classifications have been proposed for PFFD, but the most commonly used one was developed by Dr. George T. Aitken in the early 1960's. Dr. Aitken developed a four class (Class A,B,C,D) classification system based on X-ray results. Class A is the least severe and Class D is the worst case.

It is hard to classify into only four classes a condition that has widely varying degrees of severity with no clear agreement on end points. Perhaps because of its generality, the Aitken Classes appear to be the most widely used and recognized.

FIGURE 2 Schematic representation of the four radiographic subclasses
of proximal femoral focal deficiency.

First, it's important to at least understand the name PFFD. It's really not as bad as it seems. Let's look at each word:

• Proximal   -    nearest the point of attachment or center of the body
• Femoral    -    pertaining to the thigh bone or femur
• Focal        -    pertaining to a focus or starting point
• Deficiency -   a lack; less than the normal amount

In other words, the end of the thigh bone closest to the hip is too short or not completely developed.

PFFD is a congenital anomaly (birth defect) characterized by a failure of normal development of the proximal (upper) end of the femur (thigh bone). In most cases, the iliofemoral joint (hip) is also poorly developed. PFFD varies in severity from the mild case with a short femur but normal hip joint - to the more severe case where no hip joint is present.^{[Westin,1969]} The condition may be unilateral (one leg) or bilateral (both legs) and is often associated with other birth defects.^{[Aitken,1969]}