Congenital deformities about the knee are the result of abnormalities of all the anatomical structures that make up this joint. In some cases the structural changes observed are due to primary disorders of formation and growth of one or more of the anatomical components of the knee. The Congenital deformities of knee are as follow-
Genu Valgum (knock knees) – this is the condition where the knees are abnormally close to each other and ankle abnormally diverted outward. The most common type of idiopathic, the deformity basically results from the unequal growth of two sides of the growth plate of the lower femoral epiphysis or upper tibial epiphysis. Physiological genu valgum appears at the age of 2-3 years and correct at the age of 6 year.it may be associated with flat foot.
Genu Varus (bow legs) – this is the condition where the knees are abnormally away from each other and ankle abnormally diverted inward. Idiopathic is the commonest type. In others, the causes are similar to those for genu Varus but the defective growth is on the medial side of the epiphyseal plate. In this postero-medial part of the proximal tibial epiphysis fails to grow during the first 3 years of life. Severity of deformity can be measured by the distance between the two knees with the ankles held together.
Genu Recurvatum – this means hyperextension at the knee joint. Kit may be congenital or acquired. Polio is the commonest cause of acquired genu recurvatum. Other causes are
- Disease known to produce lax ligaments (Marfan syndrome, Charcot arthopathy)
- Epiphyseal growth defects
- Malunited fractures.