Pediatric Orthopedics · Proximal Femoral Focal Deficiency

Classifications and Predicting Your Child's Growth

At a Glance

Doctors classify PFFD using the Aitken and Paley systems to assess hip stability and outline surgical options. The Multiplier Method predicts the child's final leg length difference at adulthood, guiding the choice between limb-lengthening surgeries or functional prosthetic paths.

As you begin your journey with PFFD/CFD, you will hear doctors use specific systems to “score” your child’s condition. These scores are not a grade of your child’s potential; they are tools used to predict how the leg will grow and which surgical paths are safest and most effective ^[1]^[2].

The Aitken Classification: Identifying the Hip

The Aitken system is the most traditional way doctors group PFFD cases. It focuses on two main parts: the “ball” of the hip (femoral head) and the “socket” (acetabulum) [96119].

Class	What the Doctor Sees	Treatment Significance
A	A femoral head is present; the bone is short but “stable” [96119].	High potential for limb-lengthening reconstruction ^[2].
B	A femoral head is present, but it isn’t fully attached to the shaft [96119].	Requires hip stabilization before lengthening can occur ^[3].
C	The femoral head is missing; the socket (acetabulum) is shallow [96119].	Reconstruction is much more complex; often follows a prosthetic path ^[2].
D	The most severe; no femoral head or socket is present [96119].	Focus is on high-function prosthetics or Rotationplasty ^[4].

The Paley Classification: The Surgical Roadmap

The Paley classification is a more modern system designed specifically to help surgeons plan operations. Instead of just looking at what is missing, it looks at how stable the hip and knee are ^[5]^[6].

Type 1: The hip and knee are “reconstructable.” The bone is short but can be lengthened with surgery ^[6].
Type 2 & 3: These types involve more significant gaps in the bone or joint. They often require specialized procedures like the SUPERhip (to stabilize the hip) or Rotationplasty (to turn the ankle into a functional knee) ^[7]^[4].

The Multiplier Method: Predicting the Future

The most important question for many parents is: “How big will the gap be when my child is an adult?” Doctors use the Multiplier Method to answer this ^[8].

Because PFFD is a growth-rate problem, the difference between the legs grows at a constant percentage ^[8].
To understand this, imagine your baby is born with a 2-inch difference in leg length. Because the affected leg grows slower than the typical leg, that 2-inch difference will progressively widen. By the time they reach adulthood, that original gap could become an 8-inch difference.

The Calculation: Doctors take the current difference in leg length and multiply it by a specific number (the “multiplier”) based on your child’s age and sex ^[8]^[9].
Why it Matters: This provides the Predicted LLD (Limb Length Discrepancy) at maturity.
- If the predicted difference is under 15–20 cm, doctors often suggest multiple limb-lengthening surgeries over several years ^[10].
- If the predicted difference is over 20 cm, lengthening the bone that much can be very difficult for the muscles and nerves. In these cases, functional prosthetic options (like a foot amputation or Rotationplasty) are often considered to give the child better mobility with fewer total surgeries ^[10]^[11].

A Note on Outcomes

It is natural to feel that a “lower” classification or a smaller gap is “better.” However, research shows that children in both the reconstruction path and the prosthetic path grow up to have excellent quality of life and physical function ^[12]^[13]. The goal of these classifications is simply to help you and your team choose the right “tool for the job” to keep your child active and moving ^[14].

Common questions in this guide

What is the Aitken classification for PFFD?

The Aitken system categorizes PFFD based on the presence and stability of the hip's ball and socket. It ranges from Class A, where the joint has high potential for lengthening, to Class D, where both the ball and socket are missing and treatment focuses on prosthetics.

How does the Paley classification help with PFFD treatment?

The Paley classification is a surgical roadmap that focuses on how stable the hip and knee joints are. It helps orthopedic surgeons decide if the leg is reconstructable or if specialized stabilizing procedures are needed before lengthening.

What is the Multiplier Method for predicting leg length?

Because PFFD is a growth-rate issue, the difference between the legs widens over time. The Multiplier Method predicts the final gap at adulthood by multiplying the current leg length difference by a specific number based on your child's age and sex.

How does the predicted leg length discrepancy affect my child's surgical options?

If the predicted adult leg length difference is under 20 centimeters, doctors typically suggest multiple limb-lengthening surgeries. If the gap will be larger, functional prosthetics or rotationplasty are often recommended to provide better mobility with fewer total surgeries.

Does a severe PFFD classification mean a worse outcome for my child?

No, a higher classification simply means the surgical approach will be different. Research shows that children on both the reconstruction and prosthetic paths grow up to have excellent physical function and quality of life.

Curated prompts to bring to your next appointment.

1.What is my child's current Aitken classification, and does the 'ball' of the hip appear to be present on X-rays or MRI?
2.Using the Multiplier Method, what is the predicted leg length discrepancy at skeletal maturity (age 16-18)?
3.How many lengthening surgeries would likely be needed to achieve leg equality based on that prediction?
4.Does the current classification suggest the hip is stable enough for lengthening, or would we need a 'hip stabilization' procedure (like the SUPERhip) first?
5.Based on the predicted length difference, are we in the range where reconstruction is typically recommended, or should we be discussing functional prosthetic options?

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References (14)

1
Proximal Femoral Focal Deficiency/Congenital Femoral Deficiency: Evaluation and Management.
Nossov SB, Hollin IL, Phillips J, Franklin CC
The Journal of the American Academy of Orthopaedic Surgeons 2022; (30(13)):e899-e910 doi:10.5435/JAAOS-D-21-01186.
PMID: 35486897
2
Atypical Bilateral Proximal Femoral Focal Deficiency: A Case Report and Review of Literature.
Hammad A, Merkabaoui HE, Moukaddam H, et al.
Case reports in pediatrics 2026; (2026()):7521784 doi:10.1155/crpe/7521784.
PMID: 42272856
3
Management of severe congenital femoral deficiency: Does surgical intervention enhance prosthetic function?
Calder P, Elsheikh A, Cross G, et al.
Prosthetics and orthotics international 2024; (48(2)):149-157 doi:10.1097/PXR.0000000000000303.
PMID: 38019004
4
Rotationplasty for Severe Congenital Femoral Deficiency.
Fuller CB, Lichtblau CH, Paley D
Children (Basel, Switzerland) 2021; (8(6)) doi:10.3390/children8060462.
PMID: 34205839
5
Is acetabular dysplasia and pelvic deformity properly interpreted in patients with congenital femoral deficiency? A 3D analysis of pelvic computed tomography.
Musielak BJ, Shadi M, Kubicka AM, et al.
Journal of children's orthopaedics 2020; (14(5)):364-371 doi:10.1302/1863-2548.14.200065.
PMID: 33204343
6
Proximal femoral focal deficiency/congenital femoral deficiency: a proposal for a new classification.
Hosny GA, Elsheikh AA
Journal of pediatric orthopedics. Part B 2025; (34(4)):362-366 doi:10.1097/BPB.0000000000001241.
PMID: 40439062
7
Hip Joint Stability during and after Femoral Lengthening in Congenital Femoral Deficiency.
Tschurl J, Shadi M, Kotwicki T
Children (Basel, Switzerland) 2024; (11(4)) doi:10.3390/children11040500.
PMID: 38671717
8
Understanding Skeletal Growth and Predicting Limb-Length Inequality in Pediatric Patients.
Hubbard EW, Liu RW, Iobst CA
The Journal of the American Academy of Orthopaedic Surgeons 2019; (27(9)):312-319 doi:10.5435/JAAOS-D-18-00143.
PMID: 31026239
9
Height and Extremity-Length Prediction for Healthy Children Using Age-Based Versus Peak Height Velocity Timing-Based Multipliers.
Sanders JO, Karbach LE, Cai X, et al.
The Journal of bone and joint surgery. American volume 2021; (103(4)):335-342 doi:10.2106/JBJS.20.00040.
PMID: 33323887
10
Use of Paley Classification and SUPERankle Procedure in the Management of Fibular Hemimelia.
Kulkarni RM, Arora N, Saxena S, et al.
Journal of pediatric orthopedics 2019; (39(9)):e708-e717 doi:10.1097/BPO.0000000000001012.
PMID: 31503232
11
Physical function and health-related quality of life in young adults with unilateral congenital lower-limb deficiencies.
Kaastad TS, Tveter AT, Steen H, Holm I
Journal of children's orthopaedics 2017; (11(5)):348-357 doi:10.1302/1863-2548.11.170026.
PMID: 29081849
12
Amputation and rotationplasty in children with limb deficiencies: current concepts.
Sakkers R, van Wijk I
Journal of children's orthopaedics 2016; (10(6)):619-626 doi:10.1007/s11832-016-0788-7.
PMID: 27826906
13
Comparison of Outcomes by Reconstructive Strategy in Patients with Prostheses for Proximal Femoral Focal Deficiency.
Floccari LV, Jeans KA, Herring JA, et al.
The Journal of bone and joint surgery. American volume 2021; (103(19)):1817-1825 doi:10.2106/JBJS.20.02001.
PMID: 34270496
14
The Significance and Limitations of Pre- and Postnatal Imaging in the Diagnosis and Management of Proximal Focal Femoral Deficiency.
Llanes AC, Venard E, Youn S, et al.
Diagnostics (Basel, Switzerland) 2025; (15(11)) doi:10.3390/diagnostics15111302.
PMID: 40506874

This page explains PFFD classifications and growth predictions for educational purposes only. Always consult a pediatric orthopedic specialist to assess your child's specific imaging and treatment options.

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