Overview
Bilateral radio-ulnar synostosis is a condition where the two bones of the forearm — the radius and the ulna — are fused together on both arms. Normally, these two bones are separate, which allows you to rotate your forearm (the motion you use when turning a doorknob or flipping your palm up and down). When these bones are fused, this rotation is limited or completely absent in both arms. The term 'OBSOLETE' in the Orphanet listing means this specific entry has been retired or merged into a broader classification, but the condition itself is still recognized in medicine. This condition is typically present from birth because the fusion happens during fetal development when the bones of the forearm fail to separate properly. People with bilateral radio-ulnar synostosis often notice difficulty with everyday tasks that require forearm rotation, such as turning keys, using utensils, or catching a ball. The severity can vary widely — some people have mild limitations while others have significant functional challenges. Treatment is mainly focused on improving function and quality of life. Surgery may be considered in some cases to reposition the forearm in a more functional angle, though fully restoring rotation is usually not possible. Occupational therapy can help people learn adaptive techniques for daily activities. Many individuals with this condition lead full, active lives with appropriate support and adaptations.
Also known as:
Key symptoms:
Inability to rotate the forearm (cannot turn palm up or down)Stiffness in both forearmsDifficulty turning doorknobs or keysTrouble using eating utensils normallyLimited ability to catch or throw a ballDifficulty with handwriting or typingForearm fixed in a turned-in positionCompensatory shoulder or wrist movementsDifficulty carrying objects with palms facing upChallenges with personal hygiene tasks
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: Radio-ulnar synostosis, bilateral.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for OBSOLETE: Radio-ulnar synostosis, bilateral at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Radio-ulnar synostosis, bilateral.
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: Radio-ulnar synostosis, bilateral.
Community
No community posts yet. Be the first to share your experience with OBSOLETE: Radio-ulnar synostosis, bilateral.
Start the conversation →Latest news about OBSOLETE: Radio-ulnar synostosis, bilateral
No recent news articles for OBSOLETE: Radio-ulnar synostosis, bilateral.
Follow this condition to be notified when news becomes available.
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.How severe is the fusion in my child's forearms, and what position are they fixed in?,Would surgery to reposition the forearm improve daily function?,What is the best age to consider surgery if it is recommended?,Could this be part of a genetic syndrome, and should we pursue genetic testing?,What occupational therapy options are available to help with daily tasks?,Are there any adaptive devices or tools that could help with school or work activities?,Is there a risk that my other children could have this condition?
Common questions about OBSOLETE: Radio-ulnar synostosis, bilateral
What is OBSOLETE: Radio-ulnar synostosis, bilateral?
Bilateral radio-ulnar synostosis is a condition where the two bones of the forearm — the radius and the ulna — are fused together on both arms. Normally, these two bones are separate, which allows you to rotate your forearm (the motion you use when turning a doorknob or flipping your palm up and down). When these bones are fused, this rotation is limited or completely absent in both arms. The term 'OBSOLETE' in the Orphanet listing means this specific entry has been retired or merged into a broader classification, but the condition itself is still recognized in medicine. This condition is typ
At what age does OBSOLETE: Radio-ulnar synostosis, bilateral typically begin?
Typical onset of OBSOLETE: Radio-ulnar synostosis, bilateral is neonatal. Age of onset can vary across affected individuals.