Overview
Humero-ulnar synostosis, bilateral, is an extremely rare skeletal condition in which the bones of the upper arm (humerus) and one of the forearm bones (ulna) are fused together on both sides of the body. The term 'synostosis' means an abnormal joining or fusion of two bones that are normally separate. This fusion occurs at the elbow joint, which significantly limits or completely prevents the ability to bend or straighten the elbows. Because this entry is marked as 'OBSOLETE' in the Orphanet classification system, it may have been reclassified, merged into a broader category of skeletal fusion disorders, or recognized as part of another syndrome rather than standing alone as a distinct condition. Elbow synostosis can occur as an isolated finding or as part of broader genetic syndromes that affect multiple bones and joints. Affected individuals typically notice restricted arm movement from birth. Treatment is generally supportive and may include physical therapy, adaptive devices, and in some cases surgical intervention to improve range of motion. Because this is such a rare condition, management is highly individualized and often requires a team of specialists familiar with congenital skeletal abnormalities.
Also known as:
Key symptoms:
Inability to bend or straighten the elbowsStiffness in both elbow jointsLimited range of motion in the armsDifficulty with daily tasks like feeding or dressingFixed position of the elbowsPossible abnormal arm postureDifficulty reaching overhead or behind the bodyReduced ability to carry objects
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-ulnar synostosis, bilateral.
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Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Humero-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-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 synostosis an isolated finding or could it be part of a broader genetic syndrome?,Should genetic testing be performed to look for an underlying cause?,What position are the elbows fixed in, and how does that affect my child's function?,Is surgery an option to improve arm positioning or movement?,What occupational therapy services would be most helpful?,Are there adaptive devices you recommend for daily activities?,Could future children be affected by this same condition?
Common questions about OBSOLETE: Humero-ulnar synostosis, bilateral
What is OBSOLETE: Humero-ulnar synostosis, bilateral?
Humero-ulnar synostosis, bilateral, is an extremely rare skeletal condition in which the bones of the upper arm (humerus) and one of the forearm bones (ulna) are fused together on both sides of the body. The term 'synostosis' means an abnormal joining or fusion of two bones that are normally separate. This fusion occurs at the elbow joint, which significantly limits or completely prevents the ability to bend or straighten the elbows. Because this entry is marked as 'OBSOLETE' in the Orphanet classification system, it may have been reclassified, merged into a broader category of skeletal fusion
At what age does OBSOLETE: Humero-ulnar synostosis, bilateral typically begin?
Typical onset of OBSOLETE: Humero-ulnar synostosis, bilateral is neonatal. Age of onset can vary across affected individuals.