CLASSIFICATION OF ULNAR DEFICIENCY ACCORDING TO THE THUMB AND FIRST WEB

Fifty-five ulnar-deficient upper extremities in 45 patients treated al the St. Louis Shriner's Hospital were reviewed in order to evaluate t he hand abnormalities. Thumb and first-web abnormalities were noted in 73% of hands. The majority of operations (28 of 53) were recommended to improve functional deficits associated with abnormalities of the th umb and first web. A classification of the ulnar-deficient hand based upon the characteristics of the thumb and first web is presented. When used in combination with any of the six current forearm/elbow classif ication schemes, this classification more completely describes ulnar d eficiency of the upper extremity. Four classification types are propos ed based upon progressive involvement of the thumb and first web. In t ype A, the thumb and first web are normal; in type B, the first web sp ace has mild deficiency and the thumb has mild involvement. Extrinsic tendon function is intact and opposition function is present. In type C, the thumb has varying degrees of involvement. The first web has mod erate to severe deficiency, including thumb-index syndactyly, and is o ften associated with malrotation of the thumb into the plane of the ot her digits, loss of opposition, and dysfunction of the extrinsic tendo ns. In type D, the thumb is absent. Previous classifications of ulnar deficiency neglect the radial hand anomalies that have been noted by s everal authors in a high percentage of affected extremities. Our premi se for this classification is that the thumb and first-web abnormaliti es are related to the complexity of the hand problem and that the freq uently noted radial hand abnormalities require the majority of surgica l procedures. Such a classification based on the thumb and first-web d eformities will focus the surgeon's attention On those deficiencies th at are most important for the restoration of function. It is proposed that ulnar deficiency be classified by one of the classification schem es that describes the anatomy of the forearm and/or elbow supplemented by the hand classification type.