Blauth and Manske classifications for thumb hypoplasia.

Blauth's and Manske's classifications of thumb hypoplasia are widely known. Although both are used, confusion has arisen-particularly regarding the term "Blauth Type IIIB." Manske did not subdivide Blauth's Grade III; instead, he developed an independent classification system (Types I-V). Within this, Manske's Type III, defined as partial first metacarpal aplasia, was further divided into IIIA and IIIB. Blauth himself never used these subclassifications. In fact, Blauth's Grade II more closely corresponds to Manske's Type IIIA, and Blauth's Grade III to Manske's Type IIIB. Thus, the correct terminology is "Manske Type IIIB," not "Blauth Type IIIB," as the two systems are distinct. Since IIIA and IIIB imply different treatment strategies, they must be clearly distinguished. Surgeons must evaluate each case individually, as no classification is definitive, and future systems may better integrate both bony and soft tissue considerations.