Thumb function and appearance in thrombocytopenia: absent radius syndrome

Area of Science:

• Orthopedics
• Genetics
• Pediatric Medicine

Background:

• Thrombocytopenia absent radius (TAR) syndrome is a rare genetic disorder.
• It is characterized by bilateral absence of the radius and thrombocytopenia.
• Thumb abnormalities are common in TAR syndrome, affecting appearance and function.

Purpose of the Study:

• To evaluate thumb appearance and function in patients with TAR syndrome.
• To compare thumb morphology in TAR patients with age-matched controls.
• To assess functional limitations associated with thumb abnormalities in TAR syndrome.

Main Methods:

• Quantified size and shape of thumbs in 7 TAR patients, comparing them to normal controls.
• Assessed thumb function using standardized tasks.
• Analyzed thumb length, width, girth, and joint posture.

Main Results:

• TAR thumbs showed relatively normal size and shape compared to controls.
• Thumbs were held in metacarpophalangeal (MCP) flexion with an average 32-degree extension lag.
• Patients experienced significant difficulty with grasping, particularly large objects.

Conclusions:

• Thumb morphology in TAR syndrome is largely within normal limits.
• Abnormal MCP joint positioning and impaired function are characteristic of TAR syndrome thumbs.
• These findings highlight the functional challenges faced by individuals with TAR syndrome.