Overview
Humero-radio-ulnar synostosis, bilateral, is an extremely rare skeletal condition in which the bones of the upper arm (humerus) and the two forearm bones (radius and ulna) are abnormally fused together on both sides of the body. The term 'synostosis' means that bones that are normally separate have grown together, which limits or completely prevents movement at the elbow joint. Because this entry is marked as 'OBSOLETE' in the Orphanet classification system, it means the condition has likely been reclassified or merged into a broader diagnostic category, such as a more general radio-ulnar synostosis syndrome or another skeletal dysplasia. Patients with this condition typically notice significant stiffness or complete inability to bend, straighten, or rotate the elbows and forearms. This can make everyday tasks like eating, dressing, and reaching very difficult. The condition is usually present from birth, as the fusion occurs during fetal development. Treatment is mainly supportive and may include physical therapy, occupational therapy, adaptive devices, and in some cases surgery to try to improve range of motion. Because this is a very rare condition, management is best guided by specialists experienced in skeletal abnormalities.
Also known as:
Key symptoms:
Inability to bend or straighten the elbowsInability to rotate the forearms (turning palms up or down)Stiff or locked elbow joints on both sidesDifficulty with self-care tasks like eating and dressingLimited arm movement from birthForearms fixed in one positionDifficulty reaching overheadPossible abnormal arm posture
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-radio-ulnar synostosis, bilateral.
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Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Humero-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: Humero-radio-ulnar synostosis, bilateral.
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 condition part of a broader genetic syndrome, or is it isolated?,Would genetic testing help us understand the cause or risk for future children?,What surgical options exist to improve arm function?,What position are the arms fixed in, and how does that affect what my child can do?,What types of occupational therapy and adaptive devices would be most helpful?,Are there any clinical trials or research studies we could participate in?,How can we best support our child's independence at school and at home?
Common questions about OBSOLETE: Humero-radio-ulnar synostosis, bilateral
What is OBSOLETE: Humero-radio-ulnar synostosis, bilateral?
Humero-radio-ulnar synostosis, bilateral, is an extremely rare skeletal condition in which the bones of the upper arm (humerus) and the two forearm bones (radius and ulna) are abnormally fused together on both sides of the body. The term 'synostosis' means that bones that are normally separate have grown together, which limits or completely prevents movement at the elbow joint. Because this entry is marked as 'OBSOLETE' in the Orphanet classification system, it means the condition has likely been reclassified or merged into a broader diagnostic category, such as a more general radio-ulnar syno
At what age does OBSOLETE: Humero-radio-ulnar synostosis, bilateral typically begin?
Typical onset of OBSOLETE: Humero-radio-ulnar synostosis, bilateral is neonatal. Age of onset can vary across affected individuals.