Overview
Congenital genu flexum, also known as congenital knee flexion contracture or congenital flexion deformity of the knee, is a rare condition present at birth in which one or both knees are bent (flexed) and cannot be fully straightened. The knee joint is essentially locked in a bent position due to shortening or tightness of the soft tissues around the knee, including muscles, tendons, and the joint capsule. This condition can range from mild, where the knee is only slightly bent, to severe, where the knee is significantly contracted and the leg cannot extend at all. Babies born with this condition may have difficulty with leg positioning, and as they grow, walking and other movements can be affected if the contracture is not treated. In some cases, congenital genu flexum occurs on its own (isolated), while in other cases it may be associated with other birth defects or conditions such as arthrogryposis, breech positioning in the womb, or neuromuscular disorders. Treatment depends on the severity of the contracture. Mild cases may respond well to physical therapy, gentle stretching exercises, and serial casting, where casts are applied and gradually adjusted to straighten the knee over time. More severe cases may require surgical intervention to release tight tissues and allow the knee to extend properly. Early treatment generally leads to better outcomes, and many children can achieve good knee function with appropriate care.
Key symptoms:
Knee stuck in a bent position at birthInability to fully straighten the kneeStiffness in the knee jointDifficulty with leg movementAbnormal leg positioningDelayed walking milestonesLimping or unusual walking patternLeg length difference if only one knee is affectedMuscle tightness behind the kneeDifficulty standing uprightReduced range of motion in the knee
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 Congenital genu flexum.
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Specialists
View all specialists →No specialists are currently listed for Congenital genu flexum.
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 Congenital genu flexum.
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Caregiver Resources
NORD Caregiver Resources
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Mental Health Support
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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 my child's knee contracture, and what is the expected outcome with treatment?,Is this an isolated condition, or could it be part of a larger syndrome that needs further testing?,What treatment approach do you recommend — physical therapy, casting, surgery, or a combination?,How long will treatment take, and how many follow-up visits will be needed?,What can I do at home to help improve my child's knee range of motion?,Is there a chance the contracture could come back after treatment?,Will my child be able to walk and participate in normal activities as they grow?
Common questions about Congenital genu flexum
What is Congenital genu flexum?
Congenital genu flexum, also known as congenital knee flexion contracture or congenital flexion deformity of the knee, is a rare condition present at birth in which one or both knees are bent (flexed) and cannot be fully straightened. The knee joint is essentially locked in a bent position due to shortening or tightness of the soft tissues around the knee, including muscles, tendons, and the joint capsule. This condition can range from mild, where the knee is only slightly bent, to severe, where the knee is significantly contracted and the leg cannot extend at all. Babies born with this condi
At what age does Congenital genu flexum typically begin?
Typical onset of Congenital genu flexum is neonatal. Age of onset can vary across affected individuals.