summary Ulnar Club Hand is a congenital upper extremity deformity characterized by a deficiency of the ulna and/or ulnar-sided carpal structures. Diagnosis is made clinically. Treatment can be nonoperative or operative depending on hand position, thumb function, elbow stability and presence of syndactyly. Epidemiology Incidence 5-10 times less common than radial club hand Etiology Associated conditions medical not associated with systemic conditions like radial club hand orthopaedic conditions PFFD fibula deficiency scoliosis phocomelia multiple hand abnormalities almost all patients have absent ulnar sided digits Presentation Symptoms limited function usually painless Physical exam shortened, bowed forearm decrease in elbow function loss of ulnar digits Classification Bayne Classification Type 0 Deficiencies of the carpus and/or hand only Type I Undersized ulna with both growth centers present Type II Part of the ulna is missing (typically the distal ulna is absent) Type III Absent ulna Type IV Radiohumeral synostosis There is a subtype of each classification that is based on the first webspace A = Normal B = Mild deficiency of the webspace C = Moderate to severe deficiency of the webspace D = Absent webspace Treatment Goals treatment depends on multiple factors including hand position, thumb function, elbow stability, syndactyly thumb condition is most important factor to consider for treatment Nonoperative stretching and splinting indications used in early stages of treatment Operative syndactyly release and digital rotation osteotomies indications done at 12-18 months of age radial head resection and creation of a one-bone forearm indications Stage II to provide stability at the expense of forearm motion there is no good option for restoring elbow motion corrective procedures should not be performed until the child is at least 6 months old osteotomy of the synostosis indications may be required in Stage IV to obtain elbow motion