Thumb Hypoplasia.

Thumb hypoplasia is a congenital malformation resulting from disruption in upper limb development and may present as an isolated anomaly or as part of radial longitudinal deficiency. The condition encompasses a wide spectrum of anatomic and functional deficiencies, ranging from minor size reduction of the thumb to its complete absence. Proper management requires an understanding of limb embryology, accurate classification, and thorough evaluation for associated anomalies and syndromes. The Blauth classification system remains the cornerstone for guiding treatment decisions, with management strategies tailored to the stability of the carpometacarpal joint and overall thumb function. Treatment options include observation, soft tissue reconstruction with opponensplasty and ligament stabilization, or thumb ablation with index finger pollicization. Outcomes vary based on the severity of hypoplasia, associated conditions, and surgical approach, with pollicization offering favorable restoration in advanced deficiency. This article reviews the classification, evaluation, management, and outcomes of thumb hypoplasia.