Clinical Applications of the New International Terminology for the Classification of Congenital Limb Deficiencies
HECTOR W. KAY
International agreement on terminology for the classification of congenital limb deficiencies has long been sought without success, despite intermittent efforts over the past decade. In June 1973, a further attempt to establish a basis for agreement was made through the medium of a workshop established by the Research and Development Committee of the International Society for Prosthetics and Orthotics (ISPO). This workshop was specifically charged with the responsibility of proposing a system of terminology that might be internationally acceptable. As members of the workshop considered their difficult task there emerged what might be designated as a modest:
Statement of Intent
- To produce a simple descriptive terminology which could be used internationally.
- To provide an anatomical "framework" which could form the basis for more detailed or expanded syndromic, clinical or teratological classifications.
- A complete classification of congenital limb anomalies was NOT envisaged. The outcome of the workshop was a system which, it was felt, met these goals. It has been reported in several recent publications 9' 10 , The proposed new system was subsequently given tentative approval by the Executive Board of ISPO. Its basic principles are essentially simple, as follows:
Basis of Proposed Nomenclature
- The skeletal element(s) missing or affected shall be named.
- An obvious difference exists between the transverse (T-) type of deficiency, in which all elements beyond a particular level are absent, the limb resembling an amputation stump; and all other deficiencies which are termed longitudinal (L/).
- In order to achieve the simple terminology required, all presently used Greek-derived terms (e.g. -melia) should be discarded. Instead, in Transverse Deficiencies the level of absence shall be denoted by the use of arm, forearm, thigh, leg, etc., which is in line with amputation terminology. In Longitudinal Deficiencies the absent bones are named as nouns, e.g., humerus, radius, femur, tibia, etc. The adjective used as a qualifier, e.g., carpus, partial, radial, indicates that the radial part of the carpus is absent.
Since the events in Dundee a number of developments have occurred:
1. The original so-called working group was appointed as a continuing subcommittee of ISPO. The prime responsibility given this subcommittee was to follow up on the recommendations of the Dundee meeting.
2. At the request of Dr. Knud Jansen, President of ISPO, contact was made with the World Health Organization (WHO) to acquaint that body with the proposed new terminology. At the time, WHO was reported as being in the process of revising its own system for the classification of "impairments." A subsequent letter from Karel Kupka, M.D., Chief Medical Officer, International Classification of Diseases, WHO, indicated that the WHO body had immediately taken cognizance of the proposed new international system. In March 1974, copies of the WHO preliminary draft proposals for the I (impairments) and H (handicaps) Codes were received. The I Code document showed widespread incorporation of the nomenclature proposed at Dundee.
3. With regard to the broader classification of congenital anomalies proposed by Dr. Swanson 11,12,13,14 , it was agreed that, when completed, the material on skeletal limb deficiencies could be incorporated into the comprehensive system which had been accepted by the International Federation of Hand Societies.
4. As previously indicated, an article describing and illustrating the nomenclature system recommended at the Dundee workshop was written and published in the American literature, and was given international distribution.
5. At a meeting in Montreal, Que., Canada, in May 1974, the Subcommittee on Child Prosthetics Problems (SCPP) of the Committee on Prosthetics Research and Development (CPRD) had endorsed "The New International Classification Terminology."
6. The Shriners Hospitals of North America had expressed an interest in using the new system in the group's centralized data-reporting program.
7. The Task Force on Standardization of Prosthetic-Orthotic Terminology of the Committee on Prosthetic-Orthotic Education had accepted the "transverse deficits" category of the new terminology to identify amputation levels deriving from trauma or disease, and for the types of prostheses applicable to these levels.
8. Towards the end of the Dundee workshop trial applications of the proposed new terminology were made on cases available to the conferees on slides or in illustrations which had been brought to the meeting. No difficulties were experienced. However, it was agreed that more extensive trials were needed to identify any limitations or inadequacies of the new system. It was recommended, therefore, that such trials be conducted internationally under the auspices of ISPO. These tests would be done in North America with the cooperation of SCPP of CPRD and elsewhere in the world through selected child amputee clinics recruited by the author as chairman of ISPO's Subcommittee on Nomenclature and Classification in Congenital Limb Deficiency. This study was completed in August 1974.
9. On October 5, 1974, the Subcommittee on Nomenclature and Classification in Congenital Limb Deficiency met in Montreux, Switzerland, to consider the results of the study, and to make any indicated changes in the classification system.
The present report indicates the scope of the clinical applications study and reflects modifications in the system as a result of the subcommittee's deliberations.
* Assistant Executive Director, Committee on Prosthetics Research and Development, National Academy of Sciences-National Research Council, Washington, D.C. Report prepared on behalf of the Subcommittee on Child Prosthetics Problems (Leon M. Kruger, Chairman; George T. Aitken, Charles H. Epps, Jr., Sidney Fishman, Douglas A. Hobson, Claude N. Lambert, Robert E. looms) of the Committee on Prosthetics Research and Development, and the Subcommittee on Nomenclature and Classification in Congenital Limb Deficiency of ISPO [Hector W. Kay, Chairman, (U.S.A.); George I. Aitken (U.S.A.); H. J. B. Day (England); H.-L. Henkel (West Germany); Leon M. Kruger, Rapporteur (U.S.A.); Douglas W. Lamb (Scotland); Ernst Marquardt (West Germany); Ross Mitchell (Scotland); Ronan O'Rahilly (U.S.A.); Alfred B. Swanson (U.S.A.); H.-G. Willert (West Germany)].
Participants in the Study
At an impromptu executive committee meeting of SCPP held in January 1974, consideration was given to the clinical study recommended by the Dundee working group. It was agreed that, although the new terminology had been endorsed by ISPO, the material still had to be considered as being in the process of development. Hence it was thought to be premature to mount a large-scale study involving all 32 of the child amputee clinics participating in the Cooperative Research Program sponsored by SCPP. Accordingly, a limited number of centers in North America were selected to participate. In the main, these clinics were those with representation on SCPP, or the ISPO subcommittee, or both. Clinics in the United Kingdom and continental Europe selected to participate in the study were also primarily those which had been represented at the Dundee work shop ( Figure 1 ).
The Study Plan
Each participating institution was asked to classify at least 20 cases on whom data were available in the files of the clinic. Data-recording (description-classification) forms were constructed for use with both upper- and lower-limb deficiencies. Clinics were requested to shade in the missing skeletal elements on the anatomical charts and to make the appropriate classification under the new system. Samples of completed charts are shown, beginning with Figure 7 . It will be noted that provision was also made for the recording of conditions other than the basic skeletal deficiencies. Perhaps it is unnecessary to emphasize that the description-classification forms were developed and employed primarily for purposes of the study in order that the classification of each case could be checked independently. In the actual clinical application of the classification system,determinations could, and probably would, be made directly from roentgenograms. In this event, the forms could be dispensed with unless the clinic elected to complete them as part of each patient's case file.
The participants in the study were also asked to respond to a Survey of Opinions ( Figure 2 ) after they had completed the classification of their initial 20 cases.
As preliminary returns began to come in from the study it became evident that for purposes of uniformity some additional instructions to the participants were necessary. Accordingly, the chairman of the ISPO subcommittee developed and forwarded the following set of so-called Rules of Thumb to the participating clinics to guide their application of the new system.
RULES OF THUMB in the Classification of Congenital Limb Deficiencies
I. Supplemental Conditions
A. Always put absences first, followed by supplemental conditions, e.g., T-R, Ca partial; with hypoplasia of Ra and Ul.
B. In hypoplasia associated with T- deficiencies as above, name hypoplastic leg or forearm bones, since one may be affected but not the other.
II. Partial Absence of Long Bones in L/ Deficiencies.
Identify the approximate amount of the missing segment-e.g., L/L, Fem partial (prox. 3/4).
III. Order of Classification
In classifying L/ deficiencies always proceed from proximal to distal, e.g., L/R, Fem partial (prox. 3/4); Fib total; Ta partial.
In anatomical description and classification the use of abbreviations and acronyms frequently provides a system of shorthand which is of value as long as the meanings of the terms employed are essentially self-evident. In applying the new international terminology for classification of congenital limb deficiencies, it is clear that:
- Certain of the broad categories included in the system would be useful for data organization but do not have to be included for each limb classified as these categories are self-evident from the bone(s) or limb segment(s) named; for example, Upper
Limb and Lower Limb in both transverse and longitudinal deficiencies.
- The terms "transverse" and "longitudinal" themselves can be abbreviated withl little danger of confusion; for example, T-L and T-R for transverse left and right, respectively; and L/L and L/R for longitudinal left and right.
- When one or more metacarpals or metatarsals and the corresponding phalanges are completely absent, it seems unnecessary to spell out the two levels separately but simply refer to them as Rays. Similarly, when two sequent bones are affected to the same degree they could be combined in the classification. Thus, a combined longitudinal deficiency of the right upper limb, humerus total, radius total, carpus partial, metacarpal 1,2 total, phalanges 1,2 total, could more simply be written L/R, Hu and Ra total, Ca partial, Rays 1,2 total. Even more extensive contractions may be possible in ether instances; for example, classification of the case presented in Figure 9 might be simplified as L/L, Hu, Ra, Ul, Ca, and Rays l,2,3,4(?)-total.
Conversely it was pointed out by correspondents that a poorly written Fi might look like Fe and vice versa. Hence these abbreviations should be written as Fib and Fem, respectively. Similarly, maintaining Arm and Leg rather than contracting to Ar and Le might make for greater clarity at the minor cost of one additional letter per term.
Although the surgical conversion of congenital deficiencies is not a basic classification item, information on such conversion may be included on the description-classification form as supplemental data, as follows:
A. In cases of surgical amputation to provide a better limb remnant for prosthetics fitting, e.g., a Syme's-type amputation in the case of a complete absence of the fibula, a horizontal line (-) in red pencil or ink should be made on the form at the appropriate level.
B. In cases of joint fusion, e.g., in the fusion of the knee in certain cases of proximal femoral focal deficiency, the surgery should be indicated by an (X), again in red pencil or ink, through the joint fuse.
C. An osteotomy would be shown by an appropriate marking, again in red pencil or ink. For example, a Van Nes-type turnplasty might be shown by a partial circle around the osteotomized bone; an angulation osteotomy of the Marquardt type would be indicated by an angulation sign(<<).
* Modified to reflect decisions made by the Subcommittee on Nomenclature and Classification in Congenital Limb Deficiency, October 5, 1974, and now officially part of the system.
Fifteen of the institutions participating in the study submitted a total of 300 plus cases (400 plus limbs) classified under the new system. Eight of these centers were in North America, seven were in Europe.
In the majority of cases the classification of deficiencies, whether transverse or longitudinal, presented no problem. However, it seemed that in each set of cases completed by the individual clinics, a few required further thought and decision-making as to how a specific defect should be described. A sampling of these problem cases will be presented, as well as recommendations as to means for dealing with them.
Before proceeding with an analysis and discussion of the results of the field application study of the new nomenclature a brief recapitulation of the system may be in order.
It will be recalled that all congenital limb deficiencies were to be classified as either transverse or longitudinal deficits:
1. Transverse Deficiencies (T-)
This category substitutes for the terminal transverse subsection of the Frantz/O'Rahilly 3 , Hall 4 , and Burtch 2 systems; and the peromelia of the German nomenclature 5,6,7,8,15 .
Essentially, the defect presents as an amputation-like stump. In the proposed new nomenclature the deficiency is classified by naming 1) the level at which the limb terminates, or 2) the most proximal segment that is missing, it being understood that all elements distal to the level named are also absent. The nomenclature for describing the appropriate level is reproduced in Figure 3 which follows.
An application of this terminology to one of the most common types of transverse deficiency-the forearm, upper third, or short-below-elbow defect is shown in Figure 4 .
2. Longitudinal Deficiencies (L/)
All skeletal limb deficiencies other than the transverse type are placed in the longitudinal category. Thus, this subsection includes the terminal longitudinal, intercalary transverse, and intercalary longitudinal subdivisions of the Frantz/O'Rahilly, Hall, and Burtch systems; and the ectromelias of the German nomenclature.
In identifying longitudinal deficiencies all absent bones or portions of bones that are missing are named. Any bones not named as being missing are understood to be present. Figure 5 presents the application of the system to a fairly common longitudinal defect, while Figure 6 presents in chart form the language used in classifying this type of defect.
*Modified to reflect decisions made by the Subcommittee on Nomenclature and Classification in Congenital Limb Deficiency, October 5, 1974, and now officially part of the system. Attention is drawn to an oddity which apparently can occur. Total absence of the shoulder or hemipelvis (and all distal elements) would be a transverse defect. However, if only part of the shoulder or hemipelvis were absent, the deficiency would be of the longitudinal type.
Analysis of Study Data
In the study various correspondents pointed out the frequently observed fact that some bone remnants, particularly of the smaller bones, and especially in the very young child, were unidentifiable. Thus it was difficult or impossible to tell which bones were present and hence which were missing ( Figure 7 ).
This problem obviously is common to all classification systems relating to congenital limb deficiencies. It may be recalled that in one system the term "rudimentary x" was coined to cover these unknowns. In the use of the present system it is recommended that the classifier use his best judgment as to what is present or missing, but indicate by a (?) or some other designation that this is a best guess and not necessarily an exact identification.
A related problem which is also common to all systems is that x-rays taken when a child is very young may not reveal bones which are present but not yet ossified. Thus ossification done under these circumstances can only be considered as tentative and subject to revision when the child is x-rayed at a more mature age.
Completeness of the System
General Anatomical Coverage
From time to time, it is probably well to reemphasize the fact that the new nomenclature and classification system was developed to classify congenital skeletal limb deficiencies only, in accordance with the charge by ISPO to the working group. Within this constraint it appeared evident, from the cases submitted, that the system covered virtually all possible classification contingencies. In fact, in response to a question on the survey sheet which was part of the study, no cases were reported as being unclassifiable under the system. However, in reviewing individual cases it was evident that some uncertainties did exist.
In one of the earlier returns, Dr. Epps of Washington, D.C., seemed to have found a major loophole in the system when he sent in the case shown in Figure 8. This case, indicating the equivalent of a forequarter amputation, was not covered in the initial version of the nomenclature. However, upon inquiry, this deficit turned out not to be of congenital origin but to be the result of surgery (for carcinoma). If such a condition did exist as a congenital deficiency it would now be classified as a transverse deficit, shoulder total.
A case later submitted by Dr. Lamb's group in Edinburgh is shown in Figure 9*. In this patient the deficiencies in both limbs fall into the longitudinal category and the classifications of the proximal portions would be L/R, scapula partial; and L/L, scapula total. A somewhat similar case was received from the Nuffield clinic (Fig. l0)*.
If the cases cited were truly represented on the description-classification forms, they should be classifiable under the system. The charts presented as Figures 3 and 6 have been modified from the earlier version to permit this possibility. Figure 11 presents an additional illustrative case involving the lower limb.
Other Skeletal Deficiencies
The above discussion brings to mind the fact that a type of skeletal deficiency frequently leading to amputation these days and calling for prosthetic restoration involves either sacroagenesis, or complete absence of the sacrum and some portion of the lumbar spine. Some cases of this type were included in the test sample and were simply written in on line one of the appropriate description-classification form and in the classification itself. The same was true also of one or two cases of myelomeningocele when this condition lead to lower-limb amputation.
However, in considering these conditions, the members of the subcommittee agreed that, since they were not truly congenital limb deficiencies, they should not be included in the new system.
An area which required further thought was that of hypoplasia. This defect is defined in the medical dictionary as "defective or incomplete development" and provision was made to include notations concerning its presence in the classification system, but as a "secondary" condition; i.e., the primary bone absence would be noted first, followed by a notation concerning the presence of hypoplasia. For example, this deficiency, as shown in Figure 12, would be written as L/R, Hu partial (prox. 7/8); Ra total; Ca partial; Rays 1,2 total; with ulnar and scapular hypoplasia.
The frequency with which hypoplasia was reported in the trial classifications was somewhat surprising to this reviewer, as was the variety of its forms, some of which are indicated below:
- In situations where a portion of a bone was missing the remaining segment(s) might be hypoplastic or "undersized" cross-sectionally.
- In numerous instances bones might appear relatively normal in form, i.e., without the distal or proximal end being obviously missing, e.g., "congenital short femur," yet be "undersized" cross-sectionally, longitudinally, or both.
- The extent of the hypoplasia in whatever form varied from "mild" or "slight," to "severe" or "gross."
Except for the writings of Willert and Henkel, there appears to be little reference to hypoplasia or procedures for describing it in other (earlier) classification systems. A condition occurring as frequently as hypoplasia might seem to warrant special consideration in any classification scheme. However, in the interests of simplicity it was recommended by the members of the ISPO subcommittee that hypoplasia be left as a supplemental condition in the new system, as indicated in the Rules of Thumb. The detail used in describing the condition would be a matter of individual option.
* Note that in these cases, as well as in Figure 7 , the classification is not in agreement with the chart, i.e., the bones shaded as being absent would indicate a different classification.
Need for Additional Detail
As presently constituted, the basic classification system seems to provide sufficient depth of information for general purpose, classification of population, and census studies. Moreover, by virtue of the manner in which the description-classification forms were constructed, the location and notation of additional skeletal aberrations such as fusion, synostoses, bifid bones, duplications, subluxations, dislocations, etc., could be included readily. Provision was also made for recording anomalies affecting body parts other than the limbs. It has been indicated elsewhere that in clinical practice the use of the description-classification forms themselves would be optional. Similarly, the extent to which these additional aspects of the classification system are used would appear to depend primarily on the interest and energy of each specific center and the degree of detail and completeness desired.
Investigators with interests in special areas such as the ulna, the radius, the hand, the foot, hypoplasia, or whatever it might be, and seeking additional information in one or more of these areas, could expand on the current basic system to obtain the detailed data they desire. However, it is recommended that greater depth in recording or reporting should not be required of clinicians in general.
Some Specific Incongruities
Many of the respondents in the "shakedown" study indicated that the application of the new nomenclature to transverse deficiencies was so simple and straightforward that after trying a few sample cases they passed on to the more challenging longitudinal deficits. Nevertheless some specific questions requiring resolution did arise:
Bones Terminating at Different Levels
Figure 13 , Figure 14 , and Figure 15 illustrate a circumstance which occurred seven or eight times in the total sample, i.e., in approximately two percent of the cases. As will be noted, the condition sometimes affects the lower limb and sometimes the upper. The illustration fromMemphis shows a transverse deficiency of the right upper limb with the radius completely absent but a small segment of ulna present. In this case, rather than classifying the condition as a transverse deficiency of the right upper limb, forearm total; or forearm upper fifth, it was agreed that the level should be designated by reference to the individual bones, i.e., radius total; ulna upper fifth.
A more striking illustration of the same phenomenon is the case reported from Princess Margaret Rose Orthopaedic Hospital. The classification here would be T-R, Ul proximal third; Ra distal third; T-L, Ut distal 1/3; Ra distal 1/10.
The case from Grand Rapids is another deficiency of the same type which would be classified as T-L, Ti upper third; Fib total.
Constriction Band Syndrome
Two occurrences of constriction band were reported. In one case (Fig. 16) the condition was associated with complete absence of the fibula and a mid-leg amputation was performed when the child was four days of age. Here the classification would apparently be straightforward as L/R, Fib total; with constriction band; converted to a mid-leg stump.
In the other case, apparently only the soft tissues of the leg were involved but infection led to a mid-leg amputation. The classification of this condition is somewhat more difficult, particularly if the condition did actually affect only the soft tissues, as it would not then fall into the classification scheme under discussion which focuses primarily on skeleta/ deficiencies.
Estimate of Missing Bone Segments
Early in the study one or two participants suggested that in partial absence of long bones the extent of the missing segment be estimated; e.g., proximal one-third, proximal three-quarters, proximal nine-tenths, etc., it being understood that these functions were estimates and were not necessarily precise mathematically. Several centers which were late in joining the study followed this pattern. It seemed to work satisfactorily and has been incorporated into the classification procedures.
Another suggestion was to use more logical language "couplings;" i.e.,either complete-incomplete; or total-partial. The latter combination was selected by the members of the subcommittee as the one preferred.
Some of the cases reported were very unusual or bizarre, or had features which seem to call for supplemental classification. A few of these cases are described below:
1. Figure 17 from the Princess Margaret Rose Orthopaedic Hospital shows a defect which appears to have the characteristics of the Aitken Type B proximal femoral focal deficiency1. In the new nomenclature, therefore, it would be correctly classified as a longitudinal deficiency of the proximal lower limb; femoral (Fem) partial. For greater completeness the missing portion would be designated as the intermediate quarter or intermediate third, or whatever it happened to be. In cases such as this the classification or description could be made more complete by including the Aitken PFFD classification. It was agreed that this should be done.
2. Figure 18 , also from Princess Margaret Rose Orthopaedic Hospital, seems to show a case with proximal and distal ossific centers present for the femora but with the remainder of these bones plus the fibulae absent bilaterally. This defect would again be classified at least tentatively as an intermediate femoral defect.
3. Figure 19 and Figure 20 seem to show lower-limb deficits of the Aitken PFFD Types C or D. Again, for completeness of classification it would be good to include such information and also to indicate the amount of femur absent. In these cases, the absent femoral portion would, of course, be proximal.
4. Dr. Marquardt's set of cases showed a number of fairly standard proximal femoral focal deficiencies. For example, Figure 21 and Figure 22 show fairly standard Aitken Type Bs. However, Figure 23 shows a bilateral case with a "free little" femoral head but no acetabulum on the right side and synostosis between the femoral head and the acetabulum on the left. Dr. Marquardt indicates that in some respects the defects resemble Aitken's Type D; but Type D, of course, has neither femoral head nor acetabulum. Figure 24 shows defects somewhat similar to Aitken's Type C PFFD but with remnants of the femoral heads fused to the acetabula. It should be noted that these last two cases can be classified by the new terminology. However, they are presented here because of their rarity.
Survey of Opinions
As previously mentioned, a Survey of Opinions questionnaire was sent to each center in the study in order to give the participants an opportunity to express their feelings concerning the use of the new terminology. Fourteen of the fifteen centers which submitted classified cases returned this questionnaire. The responses from these centers were virtually unanimous. For example, in response to the first question concerning any limitations in the applicability of the new system, all centers reported that they had not encountered any case which could not be classified under the system. In answer to question four, Do you have any suggestions for improving or clarifying the new system or its application?, several recommendations were received. Most of these have been discussed in earlier portions of this manuscript. Others such as those relating to Dr. Marquardt's unusual cases were considered at the October 1974 meeting of the ISPO subcommittee. One negative comment has not yet been completely answered. This observation was to the effect that in complex longitudinal deficits the classification tended to be inordinately long. Some progress in condensation has been made as discussed previously under ABBREVIATIONS. Doubtless other means of simplification will evolve as the system becomes used more widely.
In answer to question five, Do you favor the development of the new terminology as an international system?, the answer was again unanimously yes. Perhaps the majority of the centers were in tacit agreement with the statement emanating from the University of Illinois: "Since the original Frantz/O'RahiIy, the revised Frantz/O'Rahilly, and the European nomenclature have not proven to be universally acceptable, this present class~flcation would seem more likely to be adopted by most countries."
At its meeting on October 5 in Montreux, just prior to the ISPO First World Congress, the subcommittee reviewed the results of the field study and made some changes in the classification system, as reported. The subcommittee also:
- Reaffirmed its endorsement of the new system and recommended similar reendorsement by the Executive Committee of ISPO in view of the generally favorable results of the "shakedown" study.
- Proposed that its membership be expanded to include representation from additional nations.
- Recommended that, if the necessary staff could be made available, a further international "shakedown" study be conducted as one means of encouraging use of the new system.
- Urged that steps be taken to ensure that the new system could be coded satisfactorily for computer handling.
The results of the "shakedown" field applications of the new international terminology for the classification of congenital limb deficiencies have been presented. Fifteen specialized child amputee centers participated and collectively classified approximately 400 congenital limb deficiencies. The results of the study were generally favorable and, following the resolution of some relatively minor problems encountered in the study, the new system was reendorsed for international use.
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