Minimally Invasive Guided Growth Surgery
Bow legs and knock knees are common postural deformities in young children. In most cases the deformities are normal for the age of the child (physiological) and will spontaneously correct with further growth and development. However some cases of bow legs and knock knees are due to an underlying bone disorder (pathological) and surgery is required to achieve a satisfactory correction of the lower limb deformity. Bone disorders such as Blount’s disease, rickets, trauma, infection and bone dysplasias cause progressive deformity requiring surgical correction.
Bone deformities can be corrected by performing an osteotomy. An osteotomy is a complex procedure that involves cutting the bone, adding or removing a wedge of bone (depending on the type of deformity), and realigning the bone. The realigned bone is then fixed with pins, a rod, or with a plate and screw combination.
Bone deformities can also be corrected using minimally invasive guided growth surgery (hemi-epiphysiodesis). Hemi-epiphysiodesis is preferred to osteotomy where possible because it is a much less invasive surgical method for correcting angular deformities and allows the surgeon to address multiple deformities during the same operation.
Hemi-epiphysiodesis surgery gradually corrects bone deformity by redirecting the growth of the bone. It is performed under general anaesthesia and generally takes about an hour. During the procedure the surgeon will make a 2 centimetre incision in skin overlying the bone growth plate, through this incision a figure-eight shaped plate (smaller than a paper clip) is inserted onto the affected bone across the bone growth plate (growth centre). This allows gradual correction of the deformity to occur with further growth.
Casting is not required after hemi-epiphysiodesis surgery. Weight bearing is encouraged as soon as is tolerated after the surgery. Children usually spend one night in hospital after the procedure for pain relief. The majority of children who undergo guided growth plate surgery should be able to return to many of their normal activities within 2 to 3 weeks.
It usually takes 12-18 months for normal alignment to be achieved, but this can vary considerably. Progress of the child’s growth needs to be monitored carefully by the surgeon in the post-operative period. The 8 plates may need to be removed with a minor surgical procedure (day stay) once normal alignment has been achieved otherwise over-correction will occur.