Overview
Humero-radial synostosis (unilateral) is a very rare skeletal condition in which the humerus (the upper arm bone) and the radius (one of the two forearm bones) are fused together on one side of the body. This fusion means the elbow joint on the affected side cannot move normally, which limits the ability to bend or straighten the arm. The term 'OBSOLETE' in the official disease name means that this specific entry has been retired or reclassified in medical databases, and the condition may now be categorized under a broader group of limb bone fusion disorders or skeletal anomalies. This condition is typically present at birth and is usually noticed when a baby does not move one arm the way they move the other. The fusion can range from partial to complete, and the degree of limitation depends on how much of the joint is involved. In some cases, humero-radial synostosis occurs as an isolated finding, while in others it may be part of a larger syndrome involving other skeletal or organ abnormalities. Because this is an extremely rare condition, there is no standard medical treatment that can restore normal joint movement. Management focuses on physical therapy, occupational therapy, and sometimes surgical intervention to improve arm function and help the individual adapt to daily tasks. Orthopedic specialists work with patients to maximize the use of the affected limb and maintain quality of life.
Also known as:
Key symptoms:
Inability to bend or straighten the elbow on one sideLimited range of motion in the affected armStiffness of the elbow jointDifficulty rotating the forearm (turning palm up or down)Visible difference in arm posture compared to the other sideDifficulty with tasks requiring two-handed coordinationPossible shortening of the affected armReduced grip strength on the affected side
Variable
Can be inherited in different ways depending on the underlying gene
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for OBSOLETE: Humero-radial synostosis, unilateral.
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Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Humero-radial synostosis, unilateral.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to OBSOLETE: Humero-radial synostosis, unilateral.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Is this bone fusion an isolated finding, or could it be part of a larger syndrome?,Should my child have genetic testing to look for an underlying cause?,What type of therapy would be most helpful for improving arm function?,Is surgery an option, and what are the realistic benefits and risks?,How will this condition affect my child's growth and development over time?,Are there adaptive devices that could help with daily activities?,Should other family members be evaluated for similar skeletal issues?
Common questions about OBSOLETE: Humero-radial synostosis, unilateral
What is OBSOLETE: Humero-radial synostosis, unilateral?
Humero-radial synostosis (unilateral) is a very rare skeletal condition in which the humerus (the upper arm bone) and the radius (one of the two forearm bones) are fused together on one side of the body. This fusion means the elbow joint on the affected side cannot move normally, which limits the ability to bend or straighten the arm. The term 'OBSOLETE' in the official disease name means that this specific entry has been retired or reclassified in medical databases, and the condition may now be categorized under a broader group of limb bone fusion disorders or skeletal anomalies. This condit
At what age does OBSOLETE: Humero-radial synostosis, unilateral typically begin?
Typical onset of OBSOLETE: Humero-radial synostosis, unilateral is neonatal. Age of onset can vary across affected individuals.