Bowed legs may cause knee pain and limitations, especially as we grow older. The medical term used to describe this problem is varus and it indicates a malalignment of the lower extremity. Some people are born with bowed legs, but others may develop the problem in just one leg following an injury. The main problem with bowed legs is that osteoarthritis may develop in the inner (medial) area of the knee, causing pain, swelling, and limitations with recreational sports and eventually, problems with normal activities of daily living. This may be worsened with obesity or overuse of the knee joint, and can become a serious problem if the medial meniscus (cartilage) is removed.
Osteoarthritis may occur from bowed legs because there is an abnormal amount of stress and pressure placed on the inner portion of the knee joint. A good analogy to this problem is the wearing of a portion of a tire on a car that is out of proper alignment. If the alignment is not fixed, the tire will wear out on one side, shortening its expected lifespan.
Technically, the term osteoarthritis refers to damage to the articular cartilage in the joint. Articular cartilage is a protective layer of tissue located on the ends of bone that come together in the knee, which are the femur (thigh bone), tibial (shin bone), and patella (kneecap). There is a second type of cartilage in the knee called a meniscus. There are 2 menisci in the knee – a medial (inner) and a lateral (outer). Each meniscus is an important tissue that acts as a cushion between the femur and tibia.
Below is a photograph taken during arthroscopic surgery of a knee with normal articular cartilage surfaces and a normal meniscus.
Now, take a look at the next photograph of a knee with severe damage to the articular cartilage and no meniscus tissue left due to a prior operation in which it was removed. This severe damage requires a knee replacement operation.
High Tibial Osteotomy for Bowed Legs
Fortunately, there is an operation for bowed legs that has gained wide acceptance as a treatment option for younger or athletic patients with osteoarthritis in the inner portion of the knee. An operation called a high tibial osteotomy (HTO) may be performed in which bone in the tibia is cut and the leg is properly aligned by the surgeon. Below is a patient with bilateral severe bowed legs.
During the HTO, a small amount of bone is cut and removed from the top area of the tibia, 2-3 inches below the knee joint.
The operation involves producing an “opening wedge” of bone which aligns the knee joint and transfers the excess loads to the outside (lateral) area of the knee joint.
The fracture is set with a plate, shown below.
Patients should be aware that this procedure produces a surgical fracture of bone and must be treated carefully for 6 to 8 weeks to allow healing into the new corrected position. Special standing x-rays are taken before surgery and will be shown to you to see how the surgeon will align the knee joint into a more correct load-bearing alignment.
The indications for HTO for bowed legs are:
- Age less than 50
- Medial compartment articular cartilage damage, but not down to bone
- Medial joint pain with activity
- Bowed leg with anterior cruciate and posterolateral ligament injury, before a ligament reconstruction
- Before a meniscus transplant or articular cartilage procedure (see the Cartilage Repair section of this website for further information on cartilage repair procedures)
The contraindications to HTO are:
- Medial tibiofemoral compartment bone exposed > 15 mm x 15 mm area
- Prior lateral meniscectomy or lateral tibiofemoral compartment articular cartilage damage
- Significant lateral tibial subluxation
- Symptomatic patellofemoral arthrosis
- Medial compartment depression and concavity preventing lateral compartment loading
- Poor patient motivation or unrealistic expectations
- Prior joint infection, diabetes, rheumatoid arthritis, autoimmune diseases, malnutrition
- No joint space left in the medial compartment
Below are x-rays of a patient who has very little joint space left in the medial compartment. This patient is not a candidate for a HTO, but is a candidate for a partial knee replacement. It is very important that the surgeon understands the proper indications and contraindications for this operation, and this is where experience is paramount for a successful outcome. The goal of the procedure is to buy time before another operation becomes necessary.
Dr. Noyes has published several important papers in medical journals and textbooks on the benefits of HTO. It is important to understand that the more joint lining that is present, the higher success of this operation and of femoral osteotomy will be in terms of buying added time for the joint. Also, you must limit strenuous activities after these operations, although light recreational activities are usually possible if the joint damage is not severe. We cannot predict how much extra time these operations will buy you since each joint is different in terms of the wear.
Overall, after HTO, 70-80% of our patients achieve about 10 years of good knee function and are happy they had the procedure. The other 20-30% may have some improvement, but the joint damage continues and symptoms are not completely relieved. Fortunately, the rate of complications in our hands is quite low, due to both the experience of Dr. Noyes is performing the operation and the rehabilitation program which allows the knee to be moved right after surgery and exercises to be initiated the next day. A list of our published papers is shown below and all are available for you to read – just contact Sue Barber-Westin at firstname.lastname@example.org for a copy.
1. How has HTO changed over time to reduce the complication rates and improve the success rates?
There have been several factors in preoperative planning, operative techniques, and postoperative rehabilitation that have made a real difference in the results of HTO. These include increased precision in the calculations required to achieve the desired angular correction, such as the use of computerized navigation and special x-rays taken throughout the operation to ensure the bowed leg malalignment is corrected. Smaller incisions are used, with less dissection of tissues which means a less invasive operation. The fracture site is secured with a high strength locking plate that allows earlier weight-bearing, reducing the amount of time patients spend on crutches. These plates also decrease the problems with healing of the fracture sites, known as nonunion or delayed union. Typically, in our clinic, patients are allowed full weight-bearing at 6 weeks after HTO.
2. What are the overall success rates of HTO?
Overall, we have noted that 70-80% of patients have a significant improvement in their symptoms and knee function. Many can return to recreational sports that allow an active lifestyle for many years after surgery. The majority can do their daily activities without problems. However, we always advise our patients that if there is already arthritis in knee joint that it will progress. About 20% of patients will not have a long-term benefit and may require a partial or total knee replacement.
3. As a younger patient who needs a large ligament reconstruction, why do I have to have a HTO first to realign my leg ?
The problem with performing any knee ligament reconstruction in a bowed leg is that there is a very high chance the new ligament graft will stretch out and fail. This happens because the bowed leg malalignment creates abnormally high forces on the lateral side of the knee. This means there is an abnormal amount of space between the femur and tibia with any weight-bearing activity and this joint opening places tremendous loads on the healing graft. The malalignment must be corrected and we usually prefer to do this first and then proceed with the ligament reconstruction a few months later, if it is still required.
4. Why is it necessary to bone graft the wedge (or gap) in an opening HTO?
In opening wedge osteotomies, a space or gap is created in the tibia. This gap must be filled with bone or the angular correction will collapse. In HTO, we have found that allograft bone (from a donor) works very well. This is advantageous for the patient because bone does not have to be taken from their hip, which used to be the case. This procedure required another incision and made the initial few postoperative weeks more uncomfortable.
5. What is rate of nonunion that requires subsequent surgery?
In our HTO studies, no further bone grafting or surgery for bone healing problems was required. We believe this was due to the type of fixation we used to stabilize the fracture site. We do inform patients that there is a 1-5% chance of a delayed union that requires the patient to spend a longer amount of time on crutches.
6. Overall, how advantageous is it to correct bowed legs?
We and many other orthopaedic centers believe it is very advantageous to have an osteotomy for a painful bowed leg. Several studies have shown that HTO buys many years before patients need further surgery such as a partial or total knee replacement. This is particularly helpful in younger patients who wish to remain active and avoid knee replacement for as long as possible. In addition, it is well known that bowed legs must be corrected in order for knee ligament surgery to be successful. Patients who require a meniscus transplant or articular cartilage restoration procedure need to have the bowed leg malalignment corrected or the procedure will most likely fail.
7. How soon will I start rehab?
In our clinic, patients begin rehabilitation the first day after surgery. It is very important during the first week to control pain and swelling, which may be done with appropriate medications, ice, and elevation of the limb. It is also important to “turn on” the muscles in the leg which may be accomplished with the assistance of modalities (such as electrical muscle stimulation) guided by a physical therapist. The early start of knee motion and muscle strength exercises reduces the risk of complications such as excessive scarring and muscle atrophy. Our rehabilitation program lasts for 6 months, but most of the exercises may be done at home or in a fitness facility.