Anatomy of the Knee Joint

The knee is the largest joint in your body and one of the most complex. Three bones meet to form the knee joint: the thighbone (femur), shinbone (tibia), and kneecap (patella). The ends of these bones, where they touch, are covered with articular cartilage, a smooth substance that protects the bones and enables them to move easily. The kneecap sits in front of the joint to provide some protection. Knee ligaments connect the thighbone to the lower leg. The four primary ligaments in the knee act like strong ropes, holding the bones together and keeping the knee stable.

Osteoarthritis can develop when the bones of your knee and leg do not line up properly, putting extra stress on either the inner (medial) or outer (lateral) side of your knee. Over time, this additional pressure can wear away the smooth cartilage that protects the bones, causing pain and stiffness in your knee.

What is an Osteotomy of the Knee?

Osteotomy literally means “cutting of the bone.” When early-stage osteoarthritis has damaged just one side of the knee joint, or when malalignment of the knee causes increased stress to ligaments or cartilage, a knee osteotomy may be performed to reshape either the tibia (shinbone) or femur (thighbone) to relieve pressure on the joint.

The procedure has three goals:

  • Transfer stress from the arthritic part of the knee to a healthier area
  • Correct poor knee alignment
  • Prolong the life span of the knee

By shifting weight off the damaged side of the joint, an osteotomy can relieve your pain and significantly improve function in your arthritic knee.

The most common osteotomy is performed on the tibia to correct a bowlegged alignment. During this procedure, a wedge of bone is removed from the outside of the shinbone, under the healthy side of the knee, or a cut is made and a wedge is placed on the inside part of the tibia (shinbone) and this area is opened. When the surgeon closes the wedge, it straightens the leg and brings the bones on the healthy side of the knee closer together, creating more space between bones on the damaged, arthritic side.

Alternatively, a wedge of bone can be placed to open the bone on the diseased side of the knee. This enables the knee to carry weight more evenly, which eases pressure on the painful side of the joint. To correct a knock-kneed alignment, an osteotomy of the femur is performed using the same technique, but on the opposite side.

Advantages of an Osteotomy

By preserving the anatomy of the joint, a successful osteotomy can relieve pain, slow progression of arthritis in the knee, and delay the need for a joint replacement by several years. There are no restrictions on physical activities after recovering from an osteotomy, so you should be able to comfortably participate in all your favorite activities, including high-impact exercise. For younger patients, this may mean many years of leading a more active lifestyle. Although many patients ultimately require a total knee replacement, an osteotomy can be an effective way to maintain quality of life while delaying joint replacement surgery.

Disadvantages

Compared with partial or total knee replacements, osteotomies provide less predictable pain relief. The recovery period following an osteotomy is typically longer and more difficult than after a partial knee replacement due to pain and the inability to put any weight on the leg immediately after the procedure. The consistently successful results of partial and total knee replacements have made knee osteotomies less common, however they remain a viable option for many patients suffering from osteoarthritis, and may be necessary to correct knee malalignment problems in conjunction with ligament injuries.

Candidates for Knee Osteotomy

If you have osteoarthritis and are able to fully straighten your knee and bend it at least 90 degrees, you may be a candidate for a knee osteotomy. Your physician may recommend this surgery if your pain: does not extend under the kneecap, is on one side of the knee only, and is brought on primarily by activity or standing for a long period of time. Knee osteotomies are most effective for people who are thin, active, and 40 to 60 years old. Patients with rheumatoid arthritis are not good candidates. Discuss this option with your orthopaedic surgeon to determine if it is suited for you.

Surgery

After admission into the hospital, you will be evaluated by a member of the anesthesia team. The most common types of anesthesia are general anesthesia (you are put to sleep) or spinal anesthesia (you are awake but your body is numb from the waist down). Your orthopaedic surgeon and your anesthesia team, with your input, will determine the best option for you. Your surgeon will see you before the surgery and sign your knee to verify the surgical site.

A knee osteotomy operation typically lasts about 2 hours. During surgery, your surgeon will make an incision at the front of your knee, starting below the kneecap. After planning out the correct size of the wedge with guide wires, your surgeon will use an oscillating saw to cut along the wires and remove the wedge of bone. The bones will then be brought together, closing, or filling, the space created by removing the wedge, or opened and a wedge will be inserted. A plate and screws will be inserted to hold the bones in place until the osteotomy heals. In some cases, a bone graft may be added to fill the space and help the osteotomy heal. After surgery, you will be taken to the recovery room where you will be closely monitored as you recover from the anesthesia. Once you’re awake, you will be moved to your hospital room.

Recovery

After surgery, your orthopaedic surgeon may put your knee in a brace or cast for protection while the bone heals. In most cases, patients remain in the hospital for 2 to 4 days after an osteotomy. During this time, you will be monitored and given pain medication.

You should expect to use crutches for several weeks. You will see your surgeon regularly in the office after the operation for follow-up visits and X-rays to determine how well the osteotomy has healed. Your doctor will tell you when it is safe to put weight on your leg, and when you can start rehabilitation, which will include exercises designed to help you maintain your range of motion and restore your strength. You may be able to resume full activities after 4 to 6 months.

Complications

As with any surgical procedure, there are risks involved with osteotomy. Your orthopaedic surgeon will discuss these with you and take specific measures to help avoid potential problems. Although infrequent, the most common complications include: infection, blood clots, stiffness of the knee joint, injuries to vessels and nerves, and failure to heal. In some cases, a second surgery is required, particularly if the osteotomy does not heal properly.