The Classification Of Congenital Skeletal Limb Deficiencies A Preliminary Report

Robert L. Burtch, RPT

The general design of a study in the classification of congenital skeletal limb deficiencies was presented in a previous article (1). The initial phase of the overall study designed to test the adequacy of a Description-Classification Form developed by the New York University Child Prosthetic Studies and of the classification terminology for congenital skeletal limb deficiencies proposed by Frantz-O'Rahilly (2), has now been completed.

The present article reviews the data received on the initial sample of children whose anomalous limbs have been described and classified by the clinics participating in the study. Since the adequacy of the forms and classification system are related basically to the description and classification of individual limbs, the emphasis is placed on a limb-by-limb analysis. We will not be concerned at this time with describing combinations of limb deficiencies (multiple limb involvement) occurring in the sample, or with associated soft tissue anomalies, surgical conversions, etc. These aspects of the data will be the subject of later analyses.

To date (September 1963) data have been obtained on 322 children from 17 of 20 children's clinics cooperating in this study. Of these children, 185 were unilaterally involved, while 137 exhibited skeletal deficiencies of more than one limb. Table 1 subdivides the children in the sample according to broad categories.

Limb-by-Limb Review

In confining our attention to a limb-by-limb review, we find that a total of 577 deficient limbs were described for the 322 children in the sample (Table 2 ). Of these 577 limbs, 471 or 85% were classifiable within the framework of the Frantz-O'Rahilly system. It is interesting to note that the greatest difficulty in classification arose with the group of bilaterally involved children, where approximately 25% of the deficient limbs described could not be classified by the current nomenclature.

The distribution of the 471 "classifiable limbs", in accordance with the Frantz-O'Rahilly system, is presented in Table 3 . It will be noted that certain deficiencies occur in combination, e.g., PFFD - T/1 FI (Proximal Femoral Focal Deficiency plus Terminal Longitudinal Complete Paraxial Hemimelia Fibular). Also, for the purposes of this report, T/3:, I/3: (Partial Adactylia) and T/4:, I/4: (Partial Aphalangia) are not followed by the specified numbers to indicate the finger rays involved. It is felt that deletion of this detail will not detract from the general description of the limbs and simplifies the presentation.

For purposes of reference, the current classification system terminology is reproduced as Table 4 .

It should be emphasized that the limited sample covered by this preliminary report cannot be considered either random or representative in the statistical sense. Hence, generalizations or extrapolations are not warranted at this time.

The approximately 15% of the present sample which could not be classified within the current format by either the cooperating clinic or the research agency will be submitted to the consideration of the Special Advisory Committee appointed by the Chairman of the Subcommittee on Children's Prosthetics Problems. Some of these limbs may be judged by this Committee to fit into the present classification system. For others, some modification or extension of the system will doubtless be necessary.

It would be beyond the scope of this interim report to present all of the 86 cases to be submitted to the Advisory Committee for review. However, two major areas where classification problems were encountered are illustrated by the following examples.

The first general area requiring consideration related to those limbs in which skeletal elements were present but hypoplastic in nature (foreshortened). This situation may involve all long bones in a given limb (Fig. 1 ), may be evident in combination with other absent skeletal elements (Fig. 2 ) or may occur in a single long bone without any accompanying skeletal deficiency (Fig. 3 ). Clinically and prosthetic-ally many of these cases may be treated as any one of the three specified types of phocomelia. Skeletally, however, they pose a classification problem.

The second general area requiring consideration concerns skeletal elements which are "unidentifiable" because of lack of form and/or position. Synostosis between hypoplastic or rudimentary elements and other long bones, as illustrated in Fig. 4 , may be found in this group.

Taking into consideration the fact that 85%, and possibly more of the present sample of 557 deficient limbs were classifiable under the Frantz-O'Rahilly scheme, it would appear that this system provides a relatively simple yet comprehensive means by which a large majority of congenital skeletal limb deficiencies may be accurately classified. Further, it would seem reasonable to anticipate that an expansion and/or modification of the present system should provide the nomenclature necessary to accommodate many if not all of those cases that apparently require further clarification at this time.

Only one comment was received regarding the Description-Classification Form, per se. This comment was to the effect that the skeletal outlines or sketches used in the form are of adults, and therefore do not give consideration to epiphyseal development. This and any other comments received will be given consideration in the revision of the form. Aside from this comment, no serious difficulties were evident in the use of the form as a descriptive instrument for classification purposes.

The next phase of the study will involve review, discussion and clarification of "difficult" cases by the Advisory Committee. A report of the findings and recommendations of this Committee will be published in the Inter-Clinic Information Bulletin as soon as they become available. Any changes or modifications in either the Description-Classification Form or in the nomenclature for classifying skeletal limb deficiencies will serve as the basis for continuation of the present study. This will involve description and classification of additional children with congenital skeletal limb deficiencies by the cooperating children's clinics. As will be recalled, one of the primary purposes of the study of congenital skeletal limb deficiencies, beyond this initial "shakedown" phase, is to "... provide a central 'pool' into which the . . . data may be channeled in order to establish a 'running account' of the types and incidence of congenital skeletal limb deficiencies over a long-term period . . .".

The Subcommittee on Children's Prosthetics Problems and the staff of the New York University Child Prosthetic Studies wish to express sincere appreciation to the Clinic Chiefs and all clinic personnel who have participated in the initial phase of this study.

Robert Burtch is Assistant Project Director, Child Prosthetic Studies, New York University, New York, New York

1. Burtch, Robert L., "A Study of Congenital Skeletal Limb Deficiencies", Inter-Clinic Information Bulletin, Volume II, Number 7, May 1963,pp.1-6.
2. Frantz, Charles H., and O'Rahilly, Ronan, "Congenital Skeletal Limb Deficiencies", Journal of Bone and Joint Surgery. 43-A: 12-2-1224, December 1961.