Joint Replacement Surgery was initially developed in Europe and Russia in the 1950’s and early 1960’s. It was first considered only a last-ditch operation for those patients suffering from incapacitating pain and disability. The first total hip arthroplasty (hip replacement) performed in the United States using a Food and Drug Administration approved bone cement was done by Dr. Mark Coventry at the Mayo Clinic in March of 1969. The development of total knee replacement systems followed during the 1970’s and dramatic advances in the design and fixation of these implants have followed over the years. Early on, patients faced highly invasive surgeries, a long recovery time, and a risk of early failure requiring revision surgery. Today, the procedure can be done much less invasively, the materials and fixation have become more durable, and long-term predictability has become a reality. Some 700,000 knee replacement and 300,000 hip replacements are performed each year in the United States. The success rate and overall patient satisfaction rates for total joint replacement is over 95%.
What is total joint replacement and why is it done?
With a healthy knee or hip, the smooth cartilage-surfaced weight bearing aspects of the joint move easily and painlessly against one another. The ligaments support the joint and the muscles move it. With an arthritic joint, these cartilage surfaces wear out and the joint becomes rough and painful. Loss of motion usually follows and the pain of weight bearing increases. Knee and hip replacement surgery becomes an option when the pain and disability from a worn out knee or hip becomes severe enough that if it interferes sufficiently with one’s activities of daily living.
The most common conditions that cause joint damage and necessitate a joint replacement are:
- Osteoarthritis. Otherwise known as “wear-and-tear” arthritis caused by genetic predisposition, congenital abnormalities, or previous trauma.
- Rheumatoid Arthritis. One of a group of “autoimmune diseases” characterized by an aggressive inflammatory intra-articular process that erodes joint surface cartilage and damages the underlying bone.
- Avascular Necrosis of the Bone. A circulatory disorder of the blood supply to the bone which causes bone deconstruction and deformity.
When conservative, non-surgical methods (rest, physical therapy, oral anti-inflammatory medications, and injections) have failed to modify the patient’s pain sufficiently, total joint replacement may be the best option for pain relief and improvement of function.
With knee and hip replacement the damaged portions of the joint are removed and then replaced by components made of hard metal and durable plastic or ceramic alternatives. These components are called prostheses and are sized to fit the individual’s own anatomy. For the knee, the components resurface all aspects of the “hinge” joint and for the hip, the components resurface the socket and replace the ball of its “ball-and-socket” joint.
What are the risks?
The most common risks associated with knee and hip replacement surgery include:
- Infection. Although the risk of an infection is relatively small following a total joint replacement, an infection can occur at any time after an implant is placed. We use special precautions to minimize this risk during the peri-operative period and our standards call for intravenous antibiotics and administered both at the time of the surgery and for 24 hours following the operation. For the rest of one’s lifetime we also recommend prophylactic antibiotics be used at the time of dental and other invasive procedures.
- Blood Clots. For some individuals, blood clots can develop in the veins of the lower extremities. These clots have the potential of breaking off and traveling to the lung or brain and can be life threatening. Blood thinners, special compressions stockings, and early mobilization are used to reduce this risk.
- Fractures. At the time of surgery, during the implantation of the prosthesis a fracture can occur to the bone in relation to the surgical site. Some fractures are small and require no treatment and others require additional surgical care.
- Dislocations. During the post-operative period, the ball and socket of a total hip replacement may dissociate one from the other. This painful event requires a “reduction” in an emergency or operating room and may also require a brace or re-operation to correct the problem. To minimize this risk, certain body positions may be restricted temporarily during the first few months following operation.
- Loosening and Wear. Although these complications are relatively rare with the newer implants and fixation techniques that are used, revisions are sometimes necessary to re-establish pain-free function. Those individuals who are young at the time of their initial replacement or who become aggressively active following a good result, are at the highest risk for needing a revision at some time during their lives.
What about the procedure?
On the day of your surgery, you will meet with your surgeon and the anesthesiologist prior to entering the operating room. After the anesthesia doctor has reviewed your medical history and examined you, a decision will be made with you regarding the type of anesthesia that is most appropriate and effective for your care. Once you enter the operating room and the anesthetic is given, you will be positioned properly and the surgical site is prepared into a sterile environment. An incision is made and carried down to the joint where the diseased cartilage and bone are removed. The size and specific secondary characteristics of the implants are determined and the final components are then implanted and secured to your own underlying healthy bone.
How about the post-operative course?
After a one to two hour stay in the recovery room, you will be admitted to the orthopaedic unit of the hospital where you will be monitored closely by the nursing staff. A physical therapist will likely see you the afternoon of surgery and allow you to sit up at the side of the bed and perhaps stand and take a few steps. Most of the formal therapy will begin the following day. We emphasize early mobilization to minimize the risks of blood clots as well as other risks associated with bed rest.
Your physical therapist will teach you the proper techniques of using crutches or walker and council you on the proper positioning of your new joint.
Most people will stay in the hospital for two or three nights and providing they have a nurturing and supportive network of family and friends available, the goal is to allow the patient to return directly to their home. It is important for the patient to feel confident and secure prior to their discharge. If additional care is required, then transitioning to a rehabilitation center prior to returning home is appropriate.
Once home, physical therapy will continue, initially in home and then as an outpatient usually after two weeks. A program of strengthening is important for a full recovery and a gradual transition from walker and crutch to a cane is encouraged. Individuals typically use a cane until they are able to walk without pain, limp, or fatigue.
What are partial knee replacements?
Partial knee replacements, sometimes referred to as unicondylar or unicompartmental knee replacements, may be performed in patients who have arthritic changes localized to only one side or compartment of their knee. For those who are candidates for this procedure, the incision is smaller, the ligaments remain completely intact, and because the normal kinematics of the knee are preserved, the recovery is usually faster.
WHAT ABOUT OTHER JOINTS?
After total knee and total hip replacements, which comprise the greatest number of joint replacements performed each year in the United States (approximately 1 million total in 2014), the next most common joint that is replaced is the shoulder. Approximately 50,000 were performed in 2014. The most common causes, as with the knee and hip, are osteoarthritis, sequelae from rheumatoid arthritis, avascular necrosis, and trauma. Depending on the nature of the arthritis and the quality of the surrounding tissues, the implant choices range from resurfacing or replacing only the ball to replacing both the ball and the socket. A so-called reverse total shoulder is used when the arthritic disease process stems primarily from a deficient or irreparable rotator cuff tear.
Hip Joint Replacement
If your hip has been damaged by arthritis, a fracture, or other conditions, common activities such as walking or getting in and out of a chair may be painful and difficult. Your hip may be stiff, and it may be hard to put on your shoes and socks. You may even feel uncomfortable while resting.
In a total hip replacement (also called total hip arthroplasty), we remove the damaged bone and cartilage and replaced it with prosthetic components.
- The damaged femoral head is removed and replaced with a metal stem that is placed into the hollow center of the femur. The femoral stem may be either cemented or “press fit” into the bone.
- A metal or ceramic ball is placed on the upper part of the stem. This ball replaces the damaged femoral head that was removed.
- The damaged cartilage surface of the socket (acetabulum) is removed and replaced with a metal socket. Screws or cement are sometimes used to hold the socket in place.
- A plastic, ceramic, or metal spacer is inserted between the new ball and the socket to allow for a smooth gliding surface.
Knee Joint Replacement
If your knee is severely damaged by arthritis or injury, it may be hard for you to perform simple activities, such as walking or climbing stairs. You may even begin to feel pain while you are sitting or lying down.
A knee replacement (also called knee arthroplasty) might be more accurately termed a knee “resurfacing” because only the surface of the bones are actually replaced.
There are four basic steps to a knee replacement procedure.
- Prepare the bone – The damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone.
- Position the metal implants – The removed cartilage and bone is replaced with metal components that recreate the surface of the joint. These metal parts may be cemented or “press-fit” into the bone.
- Resurface the patella – The undersurface of the patella (kneecap) is cut and resurfaced with a plastic button. Some surgeons do not resurface the patella, depending upon the case.
- Insert a spacer – A medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.