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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Orthopedics · Longitudinal Limb Deficiency

Types and Classifications of Longitudinal Limb Differences

At a Glance

Longitudinal limb differences, historically called hemimelia, are classified by which bone is shortened or missing. Doctors use specific systems, like the Paley classification for legs or the OMT system for arms, to determine the most effective reconstructive treatment plan for a child.

When a child is diagnosed with a longitudinal limb deficiency (historically called hemimelia), doctors use specialized classification systems to create a treatment roadmap. These systems aren’t just names; they describe the specific anatomy of the limb, including which bones are affected and how the joints—like the ankle or knee—are shaped [1][2].

The Subtype Matrix

Longitudinal deficiencies are named after the bone that is either shorter than usual (hypoplastic) or missing (aplastic). They are broadly divided into lower limb and upper limb categories:

Subtype Location Key Characteristics
Fibular Hemimelia Lower Limb The most common type; involves the small outer bone of the lower leg [3].
Tibial Hemimelia Lower Limb Involves the larger shin bone; often involves the knee’s “extensor mechanism” (the ability to straighten the leg) [2][4].
Radial Dysplasia Upper Limb Involves the thumb-side bone of the forearm; often associated with thumb differences [5].
Ulnar Dysplasia Upper Limb Involves the pinky-side bone of the forearm; less common than radial types [6].

Lower Limb Classifications

For the lower limbs, specialists use classifications that help them decide if the limb can be reconstructed (lengthened and straightened) or if other options might provide better function [7].

The Paley System (Fibular Hemimelia)

The Paley classification is a modern standard that looks beyond the fibula bone itself [1]. It focuses heavily on the ankle joint morphology—essentially, how well the foot is supported by the leg bones—as well as evaluating the knee and hip (such as for missing cruciate ligaments) [1]. This comprehensive view helps surgeons decide if procedures like a SUPERankle (a surgery to create a stable, flat-on-the-ground foot) are necessary before beginning any limb-lengthening processes [8][9].

The Jones Classification (Tibial Hemimelia)

For tibial hemimelia, the Jones classification (Types I–IV) identifies whether the shin bone is completely missing or if there is a small portion of it near the knee [10]. A critical factor in this subtype is whether the extensor mechanism (the quadriceps muscle and kneecap) is functional [4]. If this mechanism is missing, the child may not be able to straighten their knee, which significantly impacts the choice of treatment [10][4].

Upper Limb Classifications

Upper limb differences are classified to help preserve hand and wrist function, which is vital for daily tasks like writing or eating.

The Oberg-Manske-Tonkin (OMT) System

The OMT classification is the modern international standard for the hand and arm [11]. Unlike older systems that only described what the limb looked like (phenotype), the OMT system groups differences by their embryological origin (how they formed in the womb) [12][13]. This helps doctors understand if the limb difference might be linked to other health conditions and provides a more scientific way to track outcomes [14][15].

The Bayne and Klug System (Radial Dysplasia)

This system specifically focuses on radial longitudinal deficiency [16]. It ranges from Grade I (a slightly short radius) to Grade IV (the radius is completely absent) [17]. High-grade radial differences (Grades III and IV) are frequently seen alongside thumb hypoplasia (an underdeveloped or missing thumb), which requires its own specialized care plan [5][18].

Previous: Understanding Your Child’s Diagnosis | Return to Home | Next: Lower Limb Treatment Strategies

Common questions in this guide

What is the most common type of longitudinal limb difference?
Fibular hemimelia is the most common type of longitudinal limb difference. It involves the small outer bone of the lower leg, known as the fibula, being shorter than usual or missing entirely.
How do doctors determine the best treatment for fibular hemimelia?
Specialists often use the Paley classification system, which evaluates ankle joint morphology, knee stability, and hip structure. This comprehensive view helps surgeons decide if procedures like limb lengthening or ankle reconstruction are appropriate.
Why is the extensor mechanism important in tibial hemimelia?
The extensor mechanism includes the quadriceps muscle and kneecap, which allow a child to straighten their leg. If this mechanism is missing, it significantly changes the available surgical options and impacts whether the biological limb can be reconstructed.
What is the OMT classification for upper limb differences?
The Oberg-Manske-Tonkin (OMT) system groups upper limb and hand differences based on how they formed in the womb (embryological origin). This helps doctors understand if the limb difference might be linked to other underlying health conditions.
Will my child's hand function be affected by radial dysplasia?
Radial dysplasia involves a shortened or missing bone on the thumb side of the forearm and is frequently associated with an underdeveloped or missing thumb. Doctors will create a specialized care plan specifically focused on preserving vital hand and wrist function.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.In which Paley classification category does our child's fibular hemimelia fall, and what does this mean for their ankle stability and knee health?
  2. 2.For tibial hemimelia, is the 'extensor mechanism' (the quadriceps and kneecap) intact, and how does that affect the choice between reconstruction and other options?
  3. 3.How does the OMT classification help you understand the embryological cause of our child's upper limb difference?
  4. 4.Is there associated thumb hypoplasia, and if so, how will we address hand function alongside the radial deficiency?
  5. 5.Are there signs of knee instability or cruciate ligament dysplasia that we should be aware of as our child begins to walk?

Questions For You

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References

References (18)
  1. 1

    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
  2. 2

    Novel classification of tibial hemimelia and reconstruction-guiding principles.

    Hosny GA, Elmesalamy N, Hussein MA, Abdelnaser A

    International orthopaedics 2026; (50(7)):1807-1823 doi:10.1007/s00264-026-06910-3.

    PMID: 42295321
  3. 3

    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
  4. 4

    Lower Extremity Surgical Treatment to Improve Function in a Patient with Gollop-Wolfgang Complex: A Case Report.

    Albright P, Veenstra J, Habeck J, Bovid K

    JBJS case connector 2019; (9(2)):e0254 doi:10.2106/JBJS.CC.18.00254.

    PMID: 31211748
  5. 5

    Association of Radial Longitudinal Deficiency and Thumb Hypoplasia: An Update Using the CoULD Registry.

    Forman M, Canizares MF, Bohn D, et al.

    The Journal of bone and joint surgery. American volume 2020; (102(20)):1815-1822 doi:10.2106/JBJS.20.00281.

    PMID: 33086350
  6. 6

    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
  7. 7

    Amputation Versus Staged Reconstruction for Severe Fibular Hemimelia: Assessment of Psychosocial and Quality-of-Life Status and Physical Functioning in Childhood.

    Birch JG, Paley D, Herzenberg JE, et al.

    JB & JS open access 2019; (4(2)):e0053 doi:10.2106/JBJS.OA.18.00053.

    PMID: 31334463
  8. 8

    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
  9. 9

    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
  10. 10

    Deformity Reconstruction Surgery for Tibial Hemimelia.

    Chong DY, Paley D

    Children (Basel, Switzerland) 2021; (8(6)) doi:10.3390/children8060461.

    PMID: 34072809
  11. 11

    The 2020 Oberg-Manske-Tonkin classification of congenital upper limb differences: updates and challenges.

    Lam WL, Oberg KC, Goldfarb CA

    The Journal of hand surgery, European volume 2020; (45(10)):1117-1119 doi:10.1177/1753193420964335.

    PMID: 33200663
  12. 12

    Oberg-Manske-Tonkin Classification of Congenital Upper Extremity Anomalies: The First Report From Turkey.

    Uzun H, Özdemir FDM, Üstün GG, et al.

    Annals of plastic surgery 2020; (85(3)):245-250 doi:10.1097/SAP.0000000000002397.

    PMID: 32332389
  13. 13

    The Oberg-Manske-Tonkin (OMT) Classification of Congenital Upper Extremities: Update for 2020.

    Goldfarb CA, Ezaki M, Wall LB, et al.

    The Journal of hand surgery 2020; (45(6)):542-547 doi:10.1016/j.jhsa.2020.01.002.

    PMID: 32093994
  14. 14

    Identification of Associated Genes and Diseases in Patients With Congenital Upper-Limb Anomalies: A Novel Application of the OMT Classification.

    Baas M, Stubbs AP, van Zessen DB, et al.

    The Journal of hand surgery 2017; (42(7)):533-545.e4 doi:10.1016/j.jhsa.2017.03.043.

    PMID: 28669419
  15. 15

    Intraobserver and Interobserver Reliability of the Oberg-Manske-Tonkin (OMT) Classification: Establishing a Registry on Congenital Upper Limb Differences.

    Bae DS, Canizares MF, Miller PE, et al.

    Journal of pediatric orthopedics 2018; (38(1)):69-74 doi:10.1097/BPO.0000000000000732.

    PMID: 26840275
  16. 16

    Defining Features of Hand Anomalies in Severe Thumb Hypoplasia: A Classification Modification.

    Chang PS, Goldfarb CA, Bae DS, et al.

    The Journal of hand surgery 2021; (46(5)):422.e1-422.e5 doi:10.1016/j.jhsa.2020.10.005.

    PMID: 33191038
  17. 17

    Defining Features of the Upper Extremity in Holt-Oram Syndrome.

    Wall LB, Piper SL, Habenicht R, et al.

    The Journal of hand surgery 2015; (40(9)):1764-8.

    PMID: 26243320
  18. 18

    Radial Longitudinal Deficiency: Severity Differences Between U.S. and Japanese Cohorts.

    Halverson SJ, Takayama S, Ochi K, et al.

    The Journal of hand surgery 2020; (45(3)):196-202.e2 doi:10.1016/j.jhsa.2019.12.004.

    PMID: 31959377

This page provides educational information about the types and classifications of limb differences. Always consult with a pediatric orthopedic specialist for an accurate diagnosis and treatment plan for your child.

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