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Genu valgum in children with coxa vara resulting from hip disease
J S Shim1, H T Kim, S J Mubarak
1Children's Hospital, San Diego, California, USA.
Insights
Children with hip deformities like coxa vera may also have hidden knee problems (genu valgum). Correcting the hip can worsen this knee issue, potentially requiring future surgery.
Area of Science:
- Pediatric Orthopedics
- Biomechanical Engineering
Background:
- Chronic hip disease and coxa vera deformity are common in children.
- Compensatory deformities can occur but may be overlooked.
- Lower extremity biomechanics are crucial in pediatric skeletal development.
Observation:
- Three pediatric patients presented with chronic hip disease and coxa vera.
- An unrecognized, compensatory ipsilateral genu valgum was present in all patients.
- This genu valgum became apparent only after surgical correction of the hip deformity.
Findings:
- Operative correction of coxa vera laterally shifts the lower extremity's mechanical axis.
- This shift exacerbates pre-existing, occult genu valgum.
- Progressive genu valgum can occur due to abnormal Hueter-Volkmann forces on the physis.
Implications:
- Early recognition of occult genu valgum is vital before hip surgery.
- Surgeons can better counsel families on potential future knee interventions.
- This understanding improves management strategies for complex pediatric lower limb deformities.
Abstract:
Three patients with chronic hip disease and progressive coxa vera deformity also had an unrecognized compensatory ipsilateral genu valgum until the primary hip deformity had been corrected operatively. This unrecognized genu valgum may become subtly worse in a growing child because of lateralization of the mechanical axis of the lower extremity with respect to the knee joint. Operative correction of coxa vara acutely moves the mechanical axis farther laterally, causing the occult genu valgum to become clinically apparent. The genu valgum may subtly worsen over time in a growing child because of lateralization of the lower extremity mechanical axis with respect to the knee joint, with the resulting abnormal Hueter-Volkmann forces across the physis causing progressive genu valgum. Recognition of occult genu valgum before correcting coxa vara in children allows the surgeon the better to advise the family about the need for possible subsequent operations on the knee.