Knee Deformities

Knee deformities are common cause of concern, particularly in growing children and adolescents. These are of two types - knock knees where the knees collide with each other, and bow legs where there is a gap between the knees when one stands.

Knock knee deformity

This is a common problem. In milder deformities, it’s not even noticeable, particularly if one wears ankle length clothes. Nevertheless, even mild knock knees (deformed more than 3 degrees, as measured on a special, long leg – hip to ankle x-ray) have bearing on life of the knee.

Like tyre of a car, where the wheel is not aligned properly, with time due to excessive loading of one side of the knee, that side (medial side) starts to sear out early. This is felt by the patient as nagging low-grade pain and discomfort. If not taken care of at this stage, this can lead to more damage, and ultimately such knees take the shape of damaged knee and some kind of replacement surgery becomes necessary.

More obvious knock knees are visible, even with ankle length clothes. There is often a gait abnormality. Though in initial stages, it’s only a cosmetic problem, and not many people bother about it, eventually arthritis sets in and the knee becomes painful. Quite a few patients seek attention of a doctor at a stage where knock knees have already damaged outside of their joint, which has led to further deterioration of the deformity, and hence a progressive damage to the knee. Such patients are straight-away cases for surgery.

Treatment of Knock knees: We can consider treatment of knock knees into the following categories:

• Knock knees in children: Almost all children till the age of 8 years have some degree of knock knee deformity. Most of these recovers with growth.
• Knock knees in adolescent: These are youngsters who notice knock knee deformity as they pass through their pubertal growth spurt. It is more common in females. The commonest reason to seek a doctor’s advice is, cosmetic.
• Knock knees in middle age: Quite a few patients, particularly females have mild knock knees, but start developing pain in the knee when they reach 30 – 40 years of age. This may happen as they put on weight. Occurrence of pain indicates that a part of their joint is getting overloaded. Such patients would generally need surgical correction.

When does one know that one has knock knee?

It is easy to make that out. You stand in front of a mirror in your underwear. Bring both your legs close to each other. If both your knees collide and the feet are still apart, you have knock knees. It can be measured accurately with a standing long-leg x-ray (what is called hip-knee-ankle x-ray on the same film). This is done using a special software, and only can be done at select centers.

What to do if one has knock knees?

In children less than 10 years, one can ignore it, and they resolve. After this age, the patient needs to be seen by a knee specialist. The specialist would do certain x rays and blood tests to document the severity of knock knees and possible reason, if any. In case your knock knee is significant, you are likely to develop early wearing-away of your knee. Of course, it is a cosmetic problem, and needs correction.

The way to correct the deformity is by surgery. There are three methods in vogue for correcting knock knees surgically (see table for comparison):

1. Growth modulation: This is a technique where the growth centre of the lower end of the thigh bone is so regulated that one side (inner side) is forced to stop growing for some time. This is done by stopping its growth using a clamp. Over a period of time (usually a year or two), when inner side growth stops but outer side continues to grow, the growth gets equalised, and deformity gets corrected. This is done by surgery which involves putting some implant (staples or plate) across the growing part. The same is removed once the growth is compensated. In a way the growth of the limb is modulated, hence the name. The major side effect of this surgery is that (a) at least two operations are required; (b) It can only be done if sufficient growth potential is left (10 to 14 years of age); (c) it takes time for the correction to show up; (d) there is a certain amount of uncertainty about over and under correction. Second surgery is required for removal of staples. Good part is that no plaster or bone cutting is required, and the child can be pursuing his normal activity all through.

2. Corrective osteotomy: This is an age-old technique of open surgery, where the bone cut at the lower end of the thigh bone, and is realigned. It needs and incision of approximately 3 to 4 inches, and usually some kind of internal fixation device (plate or rod) is used to keep the bones in corrected position. The major side effect is a big scar. Plate removal is usually required, and hence another surgery. Other side effects are those associated with any surgery around a joint - stiffness, non-union, delayed union or malunion. It does need rest for 6 to 8 weeks for recovery. Benefit is, that it is done under direct vision, and hence a reproducible operation in average hands.

3. Key-hole surgery: This technique has been devised by us considering two main disadvantages of above conventional methods: (a) in both of them, two operations are mandatory - one for putting the implant and one for removing; (b) cosmetically unacceptable scar; (c) the correction takes a long time, and hence a long follow up in first method, as also there is potential for other complications.

In this key-hole surgery technique, through a 1cm cut, the bone is weakened from within at the strategic spot with a tool called osteotome. Once the bone is sufficiently weakened it is simply cracked, using force. This is akin to breaking a soft shoot of a plant. The bones can now be brought to corrected position. The site of weakening and correction to be achieved is monitored using a video x- ray machine (called C-arm) in the operation theatre. Once the surgeon is satisfied with the correction, a well-fitting plaster is applied from groin to just above the ankle. If the correction, by any chance, is not up to the mark, the same can be corrected simply by cutting open the plaster, correcting appropriately, and putting another plaster. There is no foreign implant inside the body, hence no second surgery for removal. The position of the bones is monitored with x-rays after 2 weeks and 4 weeks (done at home with portable x-rays machine).

The main downside of this technique is need of plaster for 3 to 4 weeks. Also, a further period of 3-4 weeks is required for consolidation of the bones before the patient is able to put the leg on the ground. This period of bed rest becomes particularly tedious for patients undergoing correction on both sides at the same time. They will have to be in bed for 6-8 weeks. In less than 5 % cases the position of the bones may move inside the plaster, and may need putting the plaster again under anaesthesia or even formal open surgery as in option 2. Rarely, the knee gets stiff more than expected and manipulation under anaesthesia (no surgery) may be required.

It is a key-hole technique and a lot depends upon the skills of the surgeon. There is a potential to damage the neuro-vascular structure of the limb, a serious complication which may need urgent surgical repair of the damaged vessel.

But, in the background of all the other benefits as mentioned above, it continues to be a popular option, particularly for young girls who do not want to exchange deformity with unsightly scar.

The usual procedure is as follows:

• Some special x-rays are carried out in the hospital.
• You are admitted on the morning of the operation. The operation is carried out sometimes during the day. It is done under general anaesthesia, and takes about 45 minutes for both sides.
• Immediately after the operation your legs would be in plater cast from groin to ankle. A check x- ray will be done to record that position of the bones are okay.
• You will be required to be in the hospital for 48 hours, after which you will be discharged. You will be required to be in bed (absolute bed rest including daily chores) for 6 to 8 weeks. This is the most taxing part of this otherwise wonderful treatment method.
• One can travel by car, ambulance, train or by air, with proper arrangements. For outstation patients within India, this is possible to go home straight from the hospital, but for out of country patients, it is desirable that they stay in Delhi for 10 days post surgery. We will help in getting suitable accommodation. Distant outstation patients and those from abroad would be permitted to travel after 10 days, once day-10 post op check x-ray is satisfactory.
• The bone position may shift within the first 10 days (1/20 cases) and a change in plaster may be required under anaesthesia and short admission. The chances of the bones shifting position after 10 days is rare, but monitoring with x-rays every 10 days is required for the first one month (day 10, day 20 and day 30).
• The plaster is kept for a period of 4 to 6 weeks (depending upon the age). No stitch removal is required as its only a small (1 cm) cut. After removal of plaster, the patient will still be in bed for another 2 weeks, but will be permitted to move the knee, but not walk.
• After 8 weeks, the patient will be trained to walk with support of a walker/crutches, under guidance of a physiotherapist. The support will be used till healing occurs, usually 3 months from the operation. It may take a few more weeks to get the knee to proper bending position. It may take another few weeks to feel fit.

In an exceptional situation, if the position of bones shifts and is not in acceptable limits, open surgery and fixation with plates and screws may become necessary (1/100). This is a proper open surgery with 6 inches cut, and additional cost (nearly double that of the first operation).

Knee deformities - Bow legs

Bow legs is also a common knee deformity. In milder forms, it’s not even noticeable, particularly if one wears ankle length clothes. Nevertheless, even mild bow legs (deformed more than 3 degrees, as measured on a special, long leg – hip to ankle x-ray) have bearing on ‘life’ of the knee. Like tyre of a car, of which the wheel is not aligned properly, due to excessive loading on one side of the knee, that side (medial side) starts to wear out early. This is felt by the patient as nagging low-intensity pain and discomfort.

If not taken care at this stage, this can lead to more damage, and ultimately such knees take the shape of damaged knee, and some kind of replacement surgery becomes necessary.

More obvious bow legs are visible, even with ankle length clothes. There is often a gait abnormality.

Though in initial stages, it’s only a cosmetic problem, and not many people bother about it, eventually arthritis sets in and the knee becomes painful.

Quite a few patients seek attention of a doctor at a stage where bow legs have already damaged inside of their joint, which has led to further deterioration of the bowing, and hence a progressive damage to the knee. Such patients are straightaway cases for surgery.

Correction of bow legs: We can consider bow legs into the following categories:

• Bow legs in children: Almost all children under the age of 4 years have bow legs, which correct automatically as the child grows. Bowlegs persisting after 8 years of age, are generally, do not self-correct, and rather increase.
• Bow-legs in adolescent: These are youngsters who notice bowing of legs as they pass through their pubertal growth spurt. It is more common in females. The commonest reason to seek a doctor’s advice is, cosmetic.
• Bow-legs in middle age: Quite a few patients, particularly females have mild bow legs, but start developing pain in their 30s and 40s, due to increase in body-weight. This indicates that a part of their joint is getting overloaded, and they generally need surgical correction.
• Bow-legs in the elderly: This an expression of age-related knee arthritis, where medial side of the knee gets more damages than the lateral side, and hence deformity comes in.

Once the knee has arthritis, and the person continues to be active, he will develop painful bowing.

When does one know that one has bow-legs?

It is easy to make that out. You stand in front of a mirror in your underwear. Bring both your feet close to each other. If a gap remains between your knees, you have bow-legs. More the gap, worse the bow-legs. One can measure the gap between the knees by ‘finger-breadths’. The same can be measured accurately with a standing long-leg x-ray (what is called hip-knee-ankle x-ray on the same film). This is done using a special software, and only can be done at select centers.

What to do if one has bow-legs?

In children less than 10 years, one can ignore it, and they resolve. After this age, the patient needs to be seen by a knee specialist. The specialist would do certain x-rays and blood tests to document the severity of bow-legs and possible reason, if any. In case your bowing of the leg is more that 3 degrees, you are likely to develop early wearing of your knee. Of course, it is a cosmetic problem, and needs correction.

The way to correct the deformity is by surgery. It consists of the following steps:

• Surgeon would find out by doing special x-rays, where the deformity is arising from, which means whether it is in the bone below or above the knee. Accordingly, corrective surgery is planned. There are two types of corrective surgery
• Growth modulation surgery: This is possible of the deformity is picked up before the child has had pubertal growth. In this, what is done is, that a clip or a small plate is put on the side of the growth plate which is growing faster, and hence temporarily stopping it on that side. Once the deformity is corrected, the clip or plate is removed.
• Corrective osteotomy: This is done when deformity is noticed only after the pubertal growth spurt has happened. The operation is called osteotomy. It is done in the bone which is deformed – tibia (bone below the knee, femur (bone above the knee) or both. Osteotomy means, cutting the bone at a strategic spot, and realigning it to get desired correction. In all probability, the correction so achieved is maintained with the help of a metallic strip (plate). Some people do not use a plate, and rather maintain the correction achieved with the help of a plaster. The surgery can be done on both legs at the same time.

Frequently asked questions (FAQs)

Is it possible that the deformity can be corrected without surgery by brace, massage, medicine and physiotherapy?

No, it’s not possible since bone deformity can only be corrected by cutting the bone and aligning it in corrected position.

What does surgery involve?

The surgery is done under anaesthesia. The bone is cut precisely with cutting tools, and then realigned. It is fixed in that position with the help of bolts and screws. It takes 2 to 3 months for the cut bone to become strong enough that one is ready to walk. A few months of home-based physiotherapy is required.

How much rest is required?

Period of bed rest is only for one day (in a corrective surgery done on one side). One can go to the bath room and walk within the house with the help of crutches. One can go back to home or office life as soon as possible. Normal walking is allowed in about 23 months from surgery.

What are the risks of surgery?

The surgery is fairly risk-proof. In some cases, delayed healing may occur. There are sometimes chances of under and over-correction. General risks of surgery such as infection, and anaesthesia related problems are rare.