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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Pediatrics · Fibular Hemimelia

Diagnosis and Anatomy of Fibular Hemimelia

At a Glance

Fibular hemimelia (FH) is a congenital field defect where the fibula is short or missing, affecting the entire leg's development. It often causes ankle tilting, tibial bowing, and missing toes. Doctors use the Paley classification to plan surgery and predict future leg length discrepancy.

Isolated Fibular Hemimelia (FH) is a congenital condition where the fibula (the thin bone on the outside of the lower leg) is shorter than normal or completely missing [1]. While the name focuses on the fibula, FH is actually a field defect, meaning it affects the development of the entire leg—from the hip and femur down to the tiny bones of the foot [2][3].

A Whole-Limb Perspective

Because FH is a field defect, doctors look beyond the missing fibula to assess other common features of the leg:

  • Ankle Valgus (Tilting): The fibula normally acts as the “outer wall” of the ankle joint. Without this wall, the ankle often tilts outward [4]. This tilting can be worsened by a fibular anlage—a tough, non-bone band of tissue where the fibula should be, which acts like a tight string pulling the ankle out of alignment [5][6].
  • Tibial Bowing: The tibia (shinbone) often has a forward or inward curve [5].
  • Foot Ray Deficiencies: It is common for children to have fewer than five toes (missing rays), though the foot can still be very functional [7][8].
  • Cruciate Ligament Dysplasia: Inside the knee, the cruciate ligaments (ACL and PCL) may be thin or missing [7][9]. This can cause the knee to feel unstable during movement [10].

Classification Systems: How Doctors “Rank” FH

Doctors use two main systems to describe the severity of FH and plan for surgery.

  • Achterman-Kalamchi focuses on Bone Absence, checking how much of the fibula is physically visible on an x-ray [11]. Type IA means part of the fibula is present, while Type II means the fibula is completely missing [11].
  • Paley Classification focuses on Ankle Stability and the shape of the ankle joint to guide surgical reconstruction [12]. Types 1 through 4 range from a stable ankle (Type 1) to a severely unstable, tilted ankle requiring complex reconstruction (Type 4) [12][13].

The Paley classification is often preferred for modern surgical planning because it tells the surgeon exactly what needs to be fixed to create a stable, flat (plantigrade) foot—the absolute prerequisite before any limb lengthening can begin [5][13].

Predicting the Future: Leg Length Discrepancy (LLD)

One of the biggest concerns for parents is predicting how short the leg will be when the child finishes growing. FH follows a growth principle called constant inhibition [14]. This means the shorter leg grows at a constant percentage of the longer leg throughout childhood [15][14].

Important note on the math: While the percentage remains constant, the absolute difference in inches or centimeters will increase as your child gets taller. For example, if the leg is 2 centimeters shorter when your child is a toddler, that gap might grow to 6 centimeters by the time they are a teenager.

Doctors use a clinical tool called the multiplier method to calculate the final LLD at skeletal maturity (when growth stops) [16]. This is a specialized medical calculation, not a DIY app for parents. As your child nears puberty, doctors will also use bone age x-rays to make these predictions even more accurate, helping you perfectly time any necessary surgeries [17][18].

Common questions in this guide

What is a fibular anlage?
A fibular anlage is a tough band of tissue that forms where the missing fibula bone should be. It acts like a tight string that can pull the ankle out of alignment, causing ankle valgus, and often needs to be addressed surgically.
Will my child's leg length difference get worse over time?
While the shorter leg grows at the same constant percentage rate as the longer leg, the actual difference in centimeters will increase as your child gets taller. Doctors use specialized calculations to predict exactly what this final difference will be.
Why does my child's knee seem unstable with fibular hemimelia?
Children with fibular hemimelia often have cruciate ligament dysplasia, which means the ACL and PCL ligaments in the knee are thin or missing. This missing internal support can cause the knee to feel unstable, shift, or clunk during movement like crawling or walking.
What is the Paley classification for fibular hemimelia?
The Paley classification is a system doctors use to evaluate ankle stability and the shape of the joint. It ranges from Type 1 to Type 4 and helps surgeons determine exactly what reconstruction is needed to create a stable foot before any limb lengthening can begin.
How do doctors predict how short my child's leg will be?
Doctors use a specialized clinical calculation called the multiplier method to forecast final leg length. As your child nears puberty, they will also use bone age x-rays to make these predictions even more accurate and help perfectly time any necessary surgeries.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my child's current limb length ratio, and how has it changed since birth?
  2. 2.Is there evidence of cruciate ligament dysplasia or knee instability, and will this need to be addressed before lengthening?
  3. 3.Does my child have a 'fibular anlage,' and if so, when should it be removed to prevent worsening of the ankle position?

Questions For You

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

References

References (18)
  1. 1

    Clinical Results and Complications of Lower Limb Lengthening for Fibular Hemimelia: A Report of Eight Cases.

    Mishima K, Kitoh H, Iwata K, et al.

    Medicine 2016; (95(21)):e3787 doi:10.1097/MD.0000000000003787.

    PMID: 27227952
  2. 2

    Upper extremity anomalies in children with femoral and fibular deficiency.

    Walker JL, White HD, Jacobs CA, Riley SA

    Journal of pediatric orthopedics. Part B 2020; (29(4)):399-402 doi:10.1097/BPB.0000000000000629.

    PMID: 30882560
  3. 3

    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
  4. 4

    Treatment of relapse valgus knee deformity in fibular hemimelia with hemiepiphysiodesis.

    Cuoghi AGS, Paccola AMF, Pagotto RF, et al.

    Journal of pediatric orthopedics. Part B 2025; (34(3)):275-281 doi:10.1097/BPB.0000000000001217.

    PMID: 39611628
  5. 5

    Ankle Reconstruction in Fibular Hemimelia: New Approach.

    Hefny H, Elmoatasem EM, Mahran M, et al.

    HSS journal : the musculoskeletal journal of Hospital for Special Surgery 2017; (13(2)):178-185 doi:10.1007/s11420-016-9524-6.

    PMID: 28690469
  6. 6

    Lateral malleolus reconstruction for fibular hemimelia as a prevention of foot deformity recurrence following tibial lengthening-A long-term analysis.

    Shadi M, Janusz P, Kortus E, Kotwicki T

    Journal of children's orthopaedics 2026; 18632521261432859 doi:10.1177/18632521261432859.

    PMID: 41943811
  7. 7

    Classification of Cruciate Ligament Dysplasia and the Severity of Congenital Fibular Deficiency.

    Walker JL, Milbrandt TA, Iwinski HJ, Talwalkar VR

    Journal of pediatric orthopedics 2019; (39(3)):136-140 doi:10.1097/BPO.0000000000000910.

    PMID: 28009801
  8. 8

    The Nature of Foot Ray Deficiency in Congenital Fibular Deficiency.

    Reyes BA, Birch JG, Hootnick DR, et al.

    Journal of pediatric orthopedics 2017; (37(5)):332-337 doi:10.1097/BPO.0000000000000646.

    PMID: 26356313
  9. 9

    Anterior and posterior cruciate ligament agenesis.

    Benassi AB, Guerreiro JPF, de Oliveira Queiroz A, et al.

    Journal of surgical case reports 2018; (2018(8)):rjy216 doi:10.1093/jscr/rjy216.

    PMID: 30151108
  10. 10

    Multi-Ligament Reconstruction in an Adolescent Female Affected by Congenital Femoral Deficiency and Complete Anterior and Posterior Cruciate Ligament agenesis: A Case Report.

    Giusti S, Bocchi MB, De Fenu E, et al.

    Clinics and practice 2024; (15(1)) doi:10.3390/clinpract15010001.

    PMID: 39851784
  11. 11

    Congenital fibular dystrophisms conform to embryonic arterial dysgenesis.

    Hootnick DR

    Anatomical record (Hoboken, N.J. : 2007) 2020; (303(11)):2792-2800 doi:10.1002/ar.24348.

    PMID: 31872958
  12. 12

    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
  13. 13

    Surgical reconstruction for fibular hemimelia.

    Paley D

    Journal of children's orthopaedics 2016; (10(6)):557-583 doi:10.1007/s11832-016-0790-0.

    PMID: 27909861
  14. 14

    Lower-extremity growth patterns and skeletal maturation in children with unilateral fibular hemimelia.

    Tsai A, Kleinman PK, Laor T, Kasser JR

    Pediatric radiology 2019; (49(1)):122-127 doi:10.1007/s00247-018-4263-0.

    PMID: 30269159
  15. 15

    Constant inhibition in congenital lower extremity shortening: does it begin in utero?

    Tsai A, Laor T, Estroff JA, Kasser JR

    Pediatric radiology 2018; (48(10)):1451-1462 doi:10.1007/s00247-018-4153-5.

    PMID: 29797037
  16. 16

    Timing of Epiphysiodesis to Correct Leg-Length Discrepancy: A Comparison of Prediction Methods.

    Makarov MR, Jackson TJ, Smith CM, et al.

    The Journal of bone and joint surgery. American volume 2018; (100(14)):1217-1222 doi:10.2106/JBJS.17.01380.

    PMID: 30020127
  17. 17

    Long-term results and comparison of the Green-Anderson and multiplier growth prediction methods after permanent epiphysiodesis using Canale's technique.

    Burger K, Farr S, Hahne J, et al.

    Journal of children's orthopaedics 2019; (13(4)):423-430 doi:10.1302/1863-2548.13.190024.

    PMID: 31489050
  18. 18

    Lengthening Reconstruction Surgery for Fibular Hemimelia: A Review.

    Fuller CB, Shannon CE, Paley D

    Children (Basel, Switzerland) 2021; (8(6)) doi:10.3390/children8060467.

    PMID: 34199455

This page explains the diagnosis and anatomy of fibular hemimelia for educational purposes. Always consult your pediatric orthopedist for specific medical advice, growth predictions, and surgical planning for your child.

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