Key-Hole Surgery For Correction Of Knock Knee

By Dr. Vinay Aggarwal in Orthopaedics & Joint Replacement

Nov 08 , 2020 | 3 min read


It not only gives rise to unsightly deformity and limp, but also has potential to damage the knee in long term. Such knees develop early arthritis in later age. One of the common reasons for the deformity in early childhood is dietary deficiency of vitamin D, but in older children, more often than not the cause cannot be found.

Can Knock Knee Deformity Correct By Itself?

Dr. Vinay Aggarwal says, "Some amount of knock knee deformity is normal in children below 8 years of age, and gets corrected by itself as the child grows. Any deformity which persists after 8 years of age is not likely to correct by itself. Knock knees persisting at adolescent, and if bad enough, will require knee replacement surgery. It is possible to accurately define the degree of knock knee deformity by special ‘weight bearing’ X ray of the whole leg, called hip-knee-ankle X-rays."

Is There A Method Of Correcting Knock Knees Without Surgery?

In the past, different types of modified shoes and braces have been used with a hope that the deformity would be corrected over time, but those have been found to be ineffective.  Any type of massage and diet does not help.

What Is key-Hole Surgery For knock Knee Correction?

This is a surgery where correction of the deformity is done through a 1 cm cut. It is done under anaesthesia. Through a small window in the bone, the deformed part of the bone is weakened from inside with the help of a special tool called osteotome.

Once the bone is weak enough and becomes pliable, it can be gently maneuvered into corrected position. The leg is subsequently put in a plaster cast for 4 weeks to let the bone heal in corrected position. There is no cutting of the muscles or the thin sheath (periosteum) covering the bone.

The deformity on both sides can be corrected at the same time. It does involve a period of bed rest and immobilization in plaster, but eventually the leg becomes straight without major surgery, and with little visible scar. This technique has been invented by the author taking into consideration that knock knees often affects young adolescent girls.

It is a cosmetic deformity, and the patient wants it corrected accept that they do not want the deformity be exchanged with a scar of a conventional surgery. Hence, one can call this technique “a cosmetic correction of a cosmetic deformity”. The author has performed this surgery on over 100 patients, and has found it a successful operation, with a low (1%) requiring conventional open surgery if the bone re-displaces inside the plaster.

Conventionally, the surgery for correcting knock knees in growing skeleton is, what is called ‘growth modulation surgery’.  This technique requires two operations - one for putting a ‘clip or plate’ to stop growth on the side of the rather rapidly growing bone, and the other to remove the clip after the deformity is corrected.

Correction happens slowly over years, and the child has to be under observation for all this period with repeated x-rays. The advantage is that there is no plaster immobilsation, and the child is more or less normally active during the duration of treatment.

There are complications associated with tinkering with growth plate and that of a foreign implant. Of course, going to the operation theatre twice, and repeated visits to the hospital over a period extending over years, is a big deterrent. Also, this surgery can only be done when there is sufficient growth potential left (between the age group of 12 to 14 years).

The other method of correcting knock knees is corrective osteotomy. This is a formal open surgery technique, where the bone is exposed by a 10 to 15 cm incision, the bone is cut and fixed with plates and screws to hold in corrected position. Though the advantage is that there is no need for plaster, but the complications related to open surgery, and need for repeat surgery for removal of plate is a deterrent.

Can Key-Hole Surgery Be Done At Any Age And Any Degree Of Deformity?

Ideal age for performing the surgery is 8 to 16 years, when the bones are relatively soft and heal faster. With growing age, the bones become harder, and are difficult to weaken by this technique. Also at that age, the healing takes a longer time, and thus longer requirement of plaster immobilization. It is not recommended in patients older than 20 years, and in those with significant obesity.