Congenital Claw Hand — Associations

Causes & Associations

1. Congenital Ulnar Nerve Aplasia / Hypoplasia

• Absence or underdevelopment of the ulnar nerve leads to paralysis of the intrinsic muscles (interossei and medial two lumbricals)
• Results in classic clawing of the ring and little fingers (4th and 5th digits)
• May be isolated or part of a syndrome

2. Arthrogryposis Multiplex Congenita (AMC)

• Congenital joint contractures affecting multiple joints
• Claw hand deformity is a recognized feature
• Caused by reduced fetal movement in utero (neurogenic, myopathic, or connective tissue causes)

3. Congenital Constriction Band Syndrome (Amniotic Band Syndrome)

• Fibrous bands constrict limbs in utero
• Can cause digital contractures resembling claw hand

4. Tibial Hemimelia

• The only long-bone deficiency with a known inheritance pattern (autosomal dominant)
• Associated with lobster-claw hand (ectrodactyly), which is a related but distinct congenital hand deformity
• Also associated with clubfoot deformity — Miller's Review of Orthopaedics 9th Edition

5. Split Hand/Foot Malformation (Ectrodactyly / "Lobster Claw")

• Distinct from true claw hand but often grouped with congenital hand deformities
• Associated with tibial hemimelia, as above

6. Leprosy (Hansen Disease) — if congenitally acquired

• Claw hand is a classic complication of ulnar nerve involvement in leprosy — Andrews' Diseases of the Skin Clinical Atlas
• Congenital transmission is rare but described

7. Epidermolysis Bullosa (EB)

• Recessive dystrophic EB causes progressive pseudosyndactyly and contractures leading to a "mitten hand" / claw deformity
• Progressive scarring fuses digits

8. Volkmann Ischemic Contracture (Congenital Vascular)

• Can occur in the newborn due to compartment syndrome in utero or perinatally
• Results in intrinsic-minus/claw hand posture due to FDP and FPL fibrosis — Miller's Review of Orthopaedics

Key Anatomical Basis

• Loss of intrinsic muscle function (lumbricals + interossei) → unopposed long extensors at MCP + unopposed long flexors at IP joints
• Ulnar nerve lesions produce "ulnar claw" (4th and 5th digits predominantly)
• Combined median + ulnar nerve lesions produce complete claw hand (all 4 fingers)
• Note the ulnar paradox: more proximal lesions cause less clawing because FDP to ring/little fingers is also paralyzed, reducing the flexion deformity at the IPs

Summary Table