While You Are in the Hospital

Range of Motion Exercises: The physical therapist will schedule your first inpatient visit shortly after surgery. Treatment will address the range of motion in the knee. Gentle movement will be used to begin to help you regain both the bending and straightening of the knee. If you are using a continuous passive motion (CPM) machine, it will be checked for alignment and settings. Next, you’ll go over your exercise regimen. When you are stabilized, your therapist will assist you during a short outing using your crutches or your walker. Treatment will proceed on a one to two time per day basis. You’ll be on your way home when you can demonstrate a safe ability to get in and out of bed, walk up to 75 feet with your crutches or walker, get up and down flight of stairs and access the bathroom. It is also important that you regain a good muscle contraction of the upper thigh muscle (quadriceps) and that you gain improved knee range of motion.

After You Leave the Hospital

Home Health Needs: Once discharged from the hospital, your therapist will likely see you for in-home treatment. This is to ensure you are safe in and about the home. You should be seen for at least one visit for the safety check and to review your exercise program. In some cases, you may require up to three visits at home before beginning outpatient physical therapy.

As You Progress

Outpatient progression: Your therapist may choose one or more modalities such as heat, ice, or electrical stimulation to help reduce persistent swelling or pain. Continue to use your walker or crutches. If you had a cemented procedure, you’ll advance the weight you place through your sore leg as much as you feel comfortable. If yours was a noncemented procedure, place only the toes down until you’ve had a follow-up x-ray and your doctor or therapist directs you to advance the amount of weight through your leg (usually by the 5th or 6th week postoperatively). Range of motion exercises and techniques will be used to help you regain full bending and straightening of the knee.

An exercise program will be developed, including strengthening, balance, endurance, and functional activities. Your strengthening program will address key muscle groups, including the buttock and hips, thigh and calf muscles. When you are safely putting full weight through the leg, several balance exercises can be chosen to further stabilize and control the knee. Endurance can be achieved through stationary biking, lap swimming, and using an upper body ergometer (upper cycle). Finally, a select group of exercises can be used to simulate day-to-day activities, like going up and down steps, squatting, raising up on your toes, and bending down. Specific exercises may then be chosen to simulate work or hobby demands.

Sometimes these knee replacement implants can wear out. Being aware of the warning signs can alert you to see your surgeon as soon as possible.

Why Does an Implant Wear Out?

• An implant can become loose
• An infection can develop near the implant
• The bone can wear away
• The implant can wear down
• Cement that bonds the implant to the bone can crack
• Fractures can occur in your thighbone, the shinbone or the implant itself

Any of the following warning signs may indicate that your knee implant is wearing out:

• Pain reoccurs in the knee or hip area after it has been without much discomfort
• Walking becomes painful in the knee
• Your knee joint becomes stiff and hard to bend and straighten
• Redness and swelling appear at and around the knee joint
• The skin over the knee joint is warm to the touch
• There is a change in the appearance or alignment of the knee

If you have concerns about your knee replacement, contact your physician right away. After your surgeon examines your knee, he or she may want you to have an X-ray or CT scan to assess your condition. Your surgeon will then be able to talk to you about the available treatment options.

Uni-compartmental knee replacement surgery utilizes specially designed implants made to resurface one side of the knee joint, and eliminate activity limiting arthritic pain restoring more normal knee function. They are attached to the ends of the femur (thigh bone) and tibia (shin bone), and move on one another during motion.

This surgery is often referred to as “less invasive” or “minimally invasive” because the procedure requires a smaller incision compared to a total knee replacement. The procedure also removes less bone and retains more of the supporting soft tissue than a total knee replacement. The existing ligaments and muscles are maintained for stability and movement of the knee. By resurfacing the arthritic bones, your arthritis pain may be reduced, allowing you to regain a more normal level of activity. Uni-compartmental knee replacement, also called partial knee replacement, may restore your knee joint’s natural range of motion, reduce pain and stiffness.

Surgical Procedure

After you have been prepared for surgery and given an anesthetic, your knee will be cleaned with a solution to sterilize the skin around the entire knee and sterile drapes will be applied to isolate your leg from the rest of your body. An incision will be made over the side of the knee where the arthritis is located. Once the knee joint is visible, the surgeon will bend and straighten your knee and check the surfaces of the bones, the ligaments, the cartilage and other structures to assess the damage to the joint. Following this assessment, your surgeon will proceed in resurfacing the arthritis or diseased knee compartment.

The surgeon will remove the worn out and damaged cartilage surfaces of the shin bone (tibia) and thigh bone (femur) at the knee joint, including small segments of bone necessary for anchoring the implants. The surgeon will use surgical instruments to remove the proper amount of bone from the tibia and femur and to assure the correct alignment of the artificial implants.

The tibial and femoral implants are inserted covering the areas where the arthritic bone has been removed. These components will be secured to the ends of the bones with a caulk-like material known as bone cement.

After the knee has been resurfaced, your surgeon will check the alignment of the implants and verify the knee joint’s range of motion by bending and straightening your leg. The layers of tissues covering you knee are then carefully repaired. The incision is closed with removable or absorbable stitches and a large bandage is applied to your knee. You will be taken off the anesthesia medication and moved to the recovery room. Partial knee replacement surgery usually takes one to two hours. You should plan to remain in the hospital for one or two days after surgery depending on your surgeon’s advice.

The steps involved in replacing the knee begin with making an incision on the front of the knee to allow access to the knee joint. There are several different approaches used to make the incision, usually based on the surgeon’s training and preferences.

Shaping the Distal Femoral Bone: Once the knee joint is entered, a special cutting jig is placed on the end of the femur. This jig is used to make sure that the bone is cut in the proper alignment to the leg’s original angles, even if the arthritis has made you bowlegged or knock-kneed. The jig is used to cut several pieces of bone from the distal femur so that the artificial knee can replace the worn surfaces with a metal surface.

Preparing the Tibial Bone: Attention is then turned toward the lower bone, the tibia. The top of the tibia is cut using another jig that ensures the alignment is satisfactory.

Preparing the Patella: The undersurface of the patella is removed.

Placing the Femoral Component: The metal femoral component is then placed on the femur. When using an uncemented femoral component, the prosthesis is held on the end of the bone through a taper on the end of the bone. In addition, the metal prosthesis is cut so that it matches the taper almost exactly. Driving the metal component onto the end of the bone holds the component in place by friction. The stable implant will allow bone tissue to grow into the porous surface, providing long-term stability. With a cemented femoral component, an epoxy cement is used to attach the metal prosthesis to the bone.

Placing the Tibial Components: The metal tray that will hold the polyethylene spacer is attached to the top of the tibia. The metal tray is either cemented into place, or may be held with screws if the component is uncemented. The screws are primarily used to hold the tibial tray in place until the bone grows into the porous coating. (The screws remain in place and are not removed.)

The plastic spacer is then attached to the metal tray of the tibial component. If this component wears out while the rest of the artificial knee is sound, it can be replaced.

Placing the Patellar Component: The patella button is usually cemented into place behind the patella.

The artificial knee replacement is now complete.

Closing the Incision: There are several ways that orthopaedic surgeons can close the incision after performing an artificial joint replacement. Stainless steel staples are popular with many orthopaedic surgeons because they are easy to put in and easy to take out. This can reduce time in the operating room. The stainless steel staples are one of the most inert types of sutures, meaning they have a very low risk of allergic reaction by the patient.

Some surgeons prefer using sutures that dissolve on their own after several weeks. These stitches are normally put in just under the skin. The advantage of this type of closure is that you don’t have to have your stitches taken out! Usually there are special tape closures (sometimes called “butterfly” tapes or “steri-strips”) that are used to hold the edges of the skin closed for the first few days. If you see strips of tape across the incision, this is probably the type of closure that was done. This type of incision closure takes a bit more time in the operating room. There is also a small chance that you may have an allergic reaction to the stitch material that delays the healing of the incision, but this risk is pretty small.

Finally, many surgeons still use the old “tried and true” nylon stitches one at a time. Nylon has withstood the test of time and is nearly as inert as stainless steel. It is strong and holds well until it is removed (somewhere between 10 to 14 days after surgery).

Implant designs vary in important ways to meet specific patient needs. Restoration of normal knee joint function is the goal of knee replacement surgery.

Some implants are designed for patients undergoing total knee surgery for the first time. This is called “primary” knee replacement.
Other implants are designed specially for people undergoing a second operation, called “revision surgery.” This is where it becomes necessary to remove the primary implant and occurs in a small percentage of cases.
Another variable is whether the implant is cemented or cementless. Most knee implants are affixed using a special bone cement similar to dental cement. Certain implants have been approved by the FDA to be implanted without bone cement and are secured biologically as the patient’s tissues grow and attach to a special porous texture that coats the implant. These are called cementless. Both types have advantages in different patient situations that your surgeon will assess. In many cases, both types are used in combination.

The most common knee implant consists of a femoral (thigh) component, a tibial (shin) and bearing components; and a patella (kneecap):

The femoral, or thighbone, component is made of metal (chromium-cobalt) and covers the lower end of the thighbone. It may be cemented to the bone or, for some implants, inserted without cement so that the patient’s tissues grow into the porous coating of the device. This natural bond between the patient’s tissue and the implant is called “biological fixation.”

The tibia, or shin bone, component is often called a “tray” and is typically made of metal (titanium or chromium-cobalt), and a plastic cushion, or bearing. The tibial component may be secured with cement or by biological fixation. The metal forms the base of this component, while the plastic (ultra-high molecular weight polyethylene) is attached to the top of the metal to serve as a bearing. This bearing creates a smooth gliding surface between the metal of the thigh and shin components.

The patella, or knee cap, component is made of either of plastic (polyethylene), or of a combination of plastic and metal. Again, this component may be fixed with or without cement.

Knee replacement surgery is considered when all available, non-operative treatments for knee arthritis have been tried without relieving the patient’s knee pain or improving their mobility. Non-operative alternatives to knee replacement surgery include pain medications; activity modifications; anti-inflammatory medications; arthroscopic joint debridement; joint realignment; physical therapy; bracing, and joint injections. Total knee replacement surgery is considered when knee pain and loss of mobility are severely affecting the quality of a person’s life.

Make the decision with your surgeon

After your orthopaedic evaluation, your surgeon will discuss alternatives with you. If x-rays show severe joint damage and no other means of treatment provides relief, total knee replacement may be recommended. Knee replacement is an elective procedure. If the pain becomes simply too much to bear, then, with your surgeon’s guidance, you’ll know when you are ready to consider knee replacement surgery.