O&P Library > Atlas of Limb Prosthetics > Chapter 33

Reproduced with permission from Bowker HK, Michael JW (eds): Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles. Rosemont, IL, American Academy of Orthopedic Surgeons, edition 2, 1992, reprinted 2002.

Much of the material in this text has been updated and published in Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles (retitled third edition of Atlas of Limb Deficiencies), ©American Academy or Orthopedic Surgeons. Click for more information about this text.

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Chapter 33 - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles

The ISO/ISPO Classification of Congenital Limb Deficiency

H.J.B. Day, M.R.C.S. (Eng.), L.R.C.P. (Lon.) 

In order to facilitate scientific communication about congenital limb deficiency, a logical, accurate system of classification and nomenclature is needed, and this must be capable of translation into all languages. The lack of a suitable system has allowed the use of the term "congenital amputation"-implying that a limb segment has been lost before birth-to be used for cases that are patently failures of formation. The use of terms derived from Greek or Latin roots may sound impressively scientific but are both inaccurate and ambiguous and are often misused, none more frequently than "phocomelia," which has been used to describe every level and type of deficiency. The history of classifications devised since 1961, including the work of the International Society for Prosthetics and Orthotics (ISPO) "Kay" committee, has been described previously by Kay, Swanson, and Day. Some further minor modifications, made more recently, have enabled the ISPO classification to be drafted and accepted by the participating nations as an international standard.


The standard is reproduced here with the permission of the International Organization for Standardization (ISO). Copies of this standard are available from the ISO Central Secretariat, Case Postale 56, CH-1211 Geneva 20, or from any ISO member body.

It has three constraints:

  1. The classification is restricted to skeletal deficiencies, and therefore the majority of such cases are due to a failure of formation of parts.
  2. The deficiencies are described on anatomic and radiologic bases only. No attempt is made to classify in terms of embryology, etiology, or epidemiology.
  3. Classically derived terms such as hemimelia, peromelia, etc., are avoided because of their lack of precision and the difficulty of translation into languages that are not related to Greek.

Deficiencies are described as transverse and longitudinal. The former resemble an amputation residual limb in which the limb has developed normally to a particular level beyond which no skeletal elements are present. All other cases are classed as longitudinal: a reduction or absence of an element or elements within the long axis of the limb.



The limb has developed normally to a particular level beyond which no skeletal elements exist, although there may be digital buds. Such deficiencies are described by naming the segment at which the limb terminates and then describing the level within the segment beyond which no skeletal elements exist (Fig 33-1.). It is possible to use another descriptor in the phalangeal case to indicate a precise level of loss within the fingers.


There is a reduction or absence of an element or elements within the long axis of the limb, and in this case there may be normal skeletal elements distal to the affected bone or bones. The following procedure should be followed to describe such a deficiency (see Fig 33-2. and Fig 33-3.):

  1. Name the bones affected in a proximodistal sequence by using the name as a noun. Any bone not named is present and of normal form.
  2. State whether each affected bone is totally or partially absent.
  3. In the case of partial deficiencies the approximate fraction and the position of the absent part may be stated.
  4. The number of the digit should be stated in relation to a metacarpal, metatarsal, and phalanges, the numbering starting from the preaxial, radial, or tibial side.
  5. The term "ray" may be used to refer to a metacarpal or metatarsal and its corresponding phalanges.

Examples of transverse and longitudinal deficiencies are shown in Fig 33-4. and Fig 33-5., but it must be understood that the stylized representation of the limb that is used in these figures is neither part of the original ISPO "Kay" committee work nor of the new international standard, but the author has found it to be the most useful way of illustrating deficiencies in clinical notes, and it can be used to indicate some treatment as well as the deficiency.


Burtch RL: Nomenclature for congenital skeletal limb deficiencies, a revision of the Frantz and O'Rahilly classification. Artif Limbs 1966; 10:24-25.

Day HJB: Nomenclature and classification in congenital limb deficiency, in Murdoch G (ed): Amputation Surgery and Lower Limb Prosthetics. Edinburgh, Blackwell Scientific Publications Inc, 1988, pp 271-278.

Frantz CH, O'Rahilly R: Congenital skeletal limb deficiencies. J Bone Joint Surg [Am] 1961; 43:1202-1204.

Henkel HL, Willert HG: Dysmelia, a classification and a pattern of malformation of congenital limb deficiencies. J Bone Joint Surg [Br] 1969; 51:399-414.

Kay HW: A proposed international terminology for the classification of congenital limb deficiencies. Inter-Clin Info Bull 1974; 13:1-16.

Kay HW: The Proposed International Terminology for the Classification of Congenital Limb Deficiencies, the Recommendations of a Working Group of ISPO. Spastics International Medical Publications, W. Heinemann Medical books Ltd, and JB Lippincott, 1975.

Swanson AB: A classification for congenital limb malformations. J Hand Surg 1976; 1:8-22.

Swanson AB: A classification for congenital malformations of the hand. N J Bull Acad Med 1964; 10:166-169.

Chapter 33 - Atlas of Limb Prosthetics: Surgical, Prosthetic, and Rehabilitation Principles

O&P Library > Atlas of Limb Prosthetics > Chapter 33

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