Congenital Knee Flexion Contracture
Congenital knee flexion contracture is the flexion deformity of knee present since birth.
A mild knee flexion deformity is not an uncommon finding in the neonate.
The positional mild knee flexion contractures are a benign, self-resolving problem likely associated with intrauterine positioning and can be viewed as a normal finding.
Significant knee flexion deformities are most commonly associated with other underlying conditions.
These conditions include primary limb dysplasias (Congenital femoral deficiency, Tibial hemimelia type 1a & 1b, Congenital quadriceps/patellar tendon dysplasia and congenital dislocation of the patella), syndromes associated with soft tissue contracture (Arthrogryposis, Popliteal pterygium syndrome, Escobar’s syndrome, Beal’s syndrome), neurologic conditions (Sacral agenesis, Myelodysplasia) and skeletal dysplasia (Diastrophic dysplasia, Metatropic dysplasia).
Mild positional knee flexion contracture may initially be up to 45 degrees. The further flexion and quadriceps function are normal. And there will be no other neurologic or dysmorphic features.
Significant knee flexion deformities with associated other underlying conditions, usually show the features of the underlying conditions like a subcutaneous fibrous band in pterygium syndrome.
Positional knee flexion contracture is usually a clinical diagnosis and it doesn’t warrant further investigation.
Significant knee flexion contracture needs evaluation with radiographs, Ultrasound scan, and Magnetic resonance imaging.
The diagnoses of the underlying condition usually require the assistance of a geneticist.
Positional knee flexion deformity, the parents can be reassured that flexion contracture will resolve in the first few months of life.
Non-operative treatment with serial manipulation and casting is indicated for mild 30 to 40 degrees contracture.
Mild contractures are treated with distal femoral extension osteotomy or distal femur anterior guided growth.
A contracture greater than 60 degrees is treated with complete posterior release and femoral shortening.
Another modality of treatment is a gradual correction with an external fixator.
Positional mild flexion deformity will not result in any long term consequences.
Other conditions with the underlying structural problems will lead to the recurrence of deformity and long term morbidity.