Knock Knees in the Pediatric Patient

 
Figure 1: Pre-operative standing x-ray demonstrating lower extremity alignment.
Figure 2: Post-operative x-rays demonstrating leg alignment after surgical correction and removal of the eight plates.

Causes

Knock knee deformity or genu valgum may be caused by a number of different conditions including metabolic diseases, renal failure, trauma and infection. It may also be idiopathic, that is, having no known cause.

Treatment

Treatment usually consists of guided growth, rather than osteotomy, with a plate and screws placed on the medial side of the knee — the opposite side from that used to correct bow leg deformity. [Figure 3]

Figure 3: Post-operative x-rays - knee x-rays demonstrating surgical hemi-epiphysiodesis utilizing an eight plate

The specific device used to achieve guided growth is the Eight Plate. This consists of a small, two-hole figure eight plate and two screws, one on each side of the growth plate.