Summary Congenital Clasped Thumb is a congenital pediatric condition that results in a flexion-adduction deformity of the thumb that persists beyond the 3rd or 4th month of life. Diagnosis is made clinically with the presence of a flexion-adduction deformity of the thumb, that is often bilateral. Treatment is usually a trial of nonoperative management with serial splinting and stretching for 3-6 months. Surgical management is indicated for persistent deformity, significant soft tissue defects or, MCP contractures. Epidemiology Demographics male-to-female ratio is approx 2.5:1 Risk factors exact causative factors are not well known possible pre-disposing factors include consanguinity family history Etiology Pathophysiology genetics autosomal dominance inheritance of variable expressivity may be sporadic pathoanatomy attenuation or deficiency of EPB (more common, in mild cases) or EPL, or both associated with 1st web contracture contracture of adductor pollicis or first dorsal interosseous muscle global instability of first MP joint abnormal articular cartilage of first MP joint Orthopedic considerations common manifestations associated with disease lower limb anomalies congenital vertical talus congenital talipes equinovarus (bilateral) upper limb anomalies flexion deformities of the four fingers Associated conditions arthrogryphosis (congenital joint contractures affect two or more areas in the body) digitotalar dysmorphisms Freeman-Sheldon syndrome X-linked MASA syndrome Classification Tsuyuguchi Classification of Clasped Thumb Type I (Supple clasped thumb) Thumb can be passively abducted and extended against resistance of thumb flexors. No other digital anomaly present. Type II (Clasped thumb with contracture) Thumb cannot be passively extended and abducted. This may occur with or without other digital anomalies. Type III (Rigid clasped thumb) Clasped thumb that is associated with arthrogryposis and marked soft-tissue deficits. Presentation History persistent flexion-adduction deformity beyond 3rd or 4th month of life, usually bilateral family history pre-natal history Symptoms pain usually with a contracture associated with other musculo-skeletal deformities Examination type of clasped thumb associated anomalies Treatment Nonoperative serial splinting and stretching for 3-6 months indications first-line treatment for all types begin treatment around the age of 6 month old outcome good definitive results with Type I congenital deformities when one of the EPL or EPB tendons are present poor results with Type I deformities when both EPL/EPB tendons are absent poor results with Type II or III deformities Operative EIP tendon transfer to EPL indications Type I or II with residual deficiency in active extension thumb reconstruction indications failed conservative treatment soft-tissue deficiency in the thumb-index finger webspace (Type III) Type II or III deformity with significant MCP joint contractures arthrodesis indications severe deformities when skin release and tendon transfer cannot overcome joint deformity. Techniques Thumb reconstruction delayed until the age of 3 to 5 years old procedure based on amount of contracture and may include 1st web widening transposition flap of skin (dorsal rotational advancement flap) four-flap or five-flap Z plasty deepening the first webspace by releasing soft-tissue releasing origins of thenar musculature from transverse carpal ligament releasing joint capsule of first MP joint tendon transfer FPL Z-lengthening in the forearm EPB and EPL absence is best reconstructed with tendon transfer isolated EPB absence will not usually require tendon transfer Complications Cosmetic appearance Instability of the MP joint Reduced thumb function