Seventy-nine-year-old Joseph Perruccio has been active his entire life and still plays senior softball three times a week. Louise Richter, 71, is an avid doubles tennis player and cares for her three grandchildren twice a week. Mr. Perruccio and Mrs. Richter are two of many Americans whose joint replacements have enabled them to return to full, active lives.

Total joint replacement, or arthroplasty (the word arthroplasty comes from arthro, joint, and plasty, surgical shaping), is one of the most important surgical advances of the past century. In fact, there are few surgical procedures that have such a positive impact on quality of life.

This two-part series will provide physical therapists with information about total hip replacement and total knee replacement. This module discusses the effects of arthritis on weight-bearing joints, such as the knee and the hip; outlines indications for joint replacement; and summarizes medical management and surgical procedures for joint replacement. The second module in the series will focus on the many roles in caring for patients with THR and TKR.

About 600,000 Americans have hip and knee joints replaced each year. These procedures are becoming increasingly common as American live longer and develop osteoarthritis, the primary indication for surgery.^1,2 A total joint replacement involves removing damaged bone and joint tissues and replacing them with metal, ceramic or plastic materials. Joint replacements for knees and hips have been used for many years, allowing people who were severely disabled to become active again.³ The demand for joint replacements is escalating because of patients’ increasing acceptance of the surgery; increasing numbers of older Americans with osteoarthritis; increasing rates of obesity, which puts added stress on cartilage that cushions knee and hip joints; and increasing numbers of older people remaining physically active in later life.

Arthritis Strikes

A joint is where two bones come together. The most common cause of chronic pain in weight-bearing joints, such as the hip and knee joints, is arthritis. Osteoarthritis, rheumatoid arthritis and traumatic arthritis are the most common forms of this disease.⁴

Osteoarthritis is a disease of articular cartilage, a soft, gel-like tissue that acts as a shock absorber for joints and protects bones from rubbing against each other.

Rheumatoid arthritis is a disease in which the synovial membrane lining the joints becomes inflamed, produces too much synovial fluid, and damages the articular cartilage, causing pain and stiffness. Traumatic arthritis can follow a serious hip or knee injury. The articular cartilage becomes damaged, causing hip pain and stiffness. A knee fracture or serious tear of the knee’s ligaments may also damage articular cartilage, producing knee pain and limiting knee function.⁴

Osteoarthritis is the most prevalent form of arthritis among Americans over age 65 and is the leading cause of chronic disability. Osteoarthritis prevalence rates are expected to increase substantially with the aging of the population. Although 90% of people 40 or older have osteoarthritis, most people don’t experience symptoms until they are in their 50s or 60s.⁵ The typical X-ray appearance of osteoarthritis shows a narrowed joint space caused by the erosion of articular cartilage. Bone may appear to be resting directly on bone because the cartilage covering the bone ends has worn away.⁵ Knee joint replacement may be recommended for knee pain that hasn’t responded to medications or physical therapy, pain that limits activities and pain that prevents a restful night’s sleep.⁶

The Wide-Ranging Hip

The hip joint is located where the ball-shaped upper end of the femur articulates with the acetabulum, a socketlike structure in the pelvis, or hip bone. A ball and socket joint permits a wide range of motion, including sitting, standing, walking and other daily activities.⁵ Activities of daily living require that a person be able to flex, abduct and externally rotate the hip. Forces across the hip joint may be three to six times body weight when walking.⁵

Disabling knee pain brought Mr. Perruccio to the physician. He had progressive pain in his left knee, especially with any type of exertion. Stair climbing caused excruciating pain. Eventually, Mr. Perruccio began to cut back on one of his loves — softball. Mr. Perruccio attributed his knee pain to the multiple injuries he had sustained as a pitcher when he had been hit in the knee. However, his physical examination and X-rays of his knee and hip showed that his major problem was not his knee, but severe arthritis affecting his hip.

Before having a total hip replacement, patients like Mr. Perruccio are usually treated conservatively. Medical management may include rest, use of a walking aid such as a cane to minimize mechanical stress across the joint and nonsurgical therapies, such as medication, joint injection and physical therapy. A cane decreases the joint force on the contralateral, or opposite, hip by reducing the amount of abductor muscle contraction needed to support body weight. This is why a cane, used properly on the side opposite a painful hip, may significantly decrease hip stress during walking. People with symptomatic osteoarthritis often take acetaminophen to help control pain.⁵ If acetaminophen doesn’t control pain, nonsteroidal anti-inflammatory agents are used for people without a history of GI problems and with normal renal function.⁵ An exercise program can strengthen the hip muscles and may decrease stress on the joint, thus aiding in pain relief.

However, when joint destruction reaches the point at which medical management strategies have little or no effect on a patient’s intense pain and limited mobility, total hip replacement may be indicated.

Mr. Perruccio met the criteria for total hip replacement and had successful joint replacement surgery. During the procedure, the surgeon removes the diseased bone tissue and cartilage around the joint. The head of the femur and the acetabulum are replaced with new, artificial parts that allow the joint to move smoothly.^4,5 Joint prostheses are classified as medical devices and are regulated by the Food and Drug Administration.⁴ The most common FDA-approved joint prostheses are made of metals such as titanium or a mixture of cobalt and chromium and a high-density polyethylene plastic.⁴

Hip replacements were developed in the 1960s and within a decade revolutionized the treatment of hip arthritis in elderly patients.⁵ In the past, hip replacement surgery was reserved primarily for patients over age 60. Typically, older people are less active and put less strain on the artificial hip than younger, more active people. In recent years, however, hip replacement surgery has been used successfully in younger people, partly because new technology has improved the replacement parts, allowing them to withstand more stress and strain.⁵ However, active, younger people may need another surgery to replace the hip joint implant after 15 to 20 years of wear.⁷ A more important factor than age in determining the success of hip replacement is the patient’s general health and activity level.

Hip replacement is not appropriate for some patients whose risk of artificial hip location is increased, such as those who have severe muscle weakness or Parkinson’s disease.⁵ Even individuals who are obese or over age 79 can have a successful total hip replacement outcome.⁸ For healthy, active people like Mr. Perruccio, total hip replacement enables the return to pain-free performance of ADLs while preventing further disability.

Minimally invasive total hip replacement is a recent option that can result in a smaller incision, less blood loss during surgery and a faster recovery.⁹ However, patients must realize that a minimal incision technique is not minimally invasive surgery. Disadvantages of minimally invasive surgery include the challenge of doing surgery in a restricted visual field, longer duration of surgery, limited implant choices and the possibility of stretching or tearing of the skin and soft tissues.⁹ Under the skin, the procedure is similar to a total hip replacement done through a standard incision, and the patient is at risk for similar complications.¹⁰ Obese patients who have undergone previous joint surgery or who have unusual joint anatomy may not be candidates for minimally invasive total hip replacement. Experts emphasize that the procedure needs further study before it can be recommended for general use.¹⁰

New and Improved Knees

The knee is the third most common site of osteoarthritis, after the spine and the hip.⁵ The first knee replacements, done in the 1950s, were not able to replicate the natural motion of the knee adequately, resulting in high failure and complication rates. Advances in knee surgery technology in the past decade have greatly improved the fit and design of knee implants. Based on research evidence, TKR is a safe and cost-effective treatment for eliminating pain and restoring mobility in people who are not helped by nonsurgical therapies.¹¹

Just as with hip replacement, people between ages 60 and 75 were traditionally considered to be the best candidates for TKR. Over the past two decades, the age range has changed to include more elderly people, many of whom have comorbid conditions, and younger people, whose implants may be exposed to greater mechanical stresses over an extended period of time.¹¹ One of the most important factors that results in successful knee replacement is correct surgical technique. Studies show that surgeons’ and institutions’ complication rates fall as the number of surgeries they do increase.¹¹

A normal knee joint has four ligaments that hold bones in place and allows adequate range of joint motion. When a knee joint is affected by arthritis, ligaments can become damaged and scarred.¹² The knee supports a great deal of weight and is prone to injury because of its exposed position and the stresses it bears.⁵ During normal walking, a force of about three times body weight is transmitted through the knee. Going up and down stairs increases this force to four to five times body weight. During athletic activities, the knee joints may absorb great stresses.⁵ As women generally live longer than men, the chances are even greater that physically active women will experience problems with their knees. Pain with stiffness is the predominant complaint of people with arthritis of the knee. The use of a cane, weight loss, activity modification, anti-inflammatory agents and analgesics all help to reduce symptoms. Isometric exercises may be used to increase quadricep and hamstring strength.

Mrs. Richter began to have knee pain that limited her everyday activities. Getting in and out of a chair and climbing stairs were particular problems. To ascend stairs, she had to hang on to the stair rail and pull herself up one stair at a time. Lacking support from her knee joint, her right leg became deformed, and she experienced severe pain. One of her favorite activities, tennis, became impossible because she couldn’t move without severe pain. Mrs. Richter’s X-ray showed that she had almost no cartilage in her right knee. A cane and a cortisone injection into the knee joint didn’t help relieve her increasingly disabling pain. Over time, she had moderate to severe knee pain even at rest. Based on her symptoms, she was a suitable candidate for TKR.

Many Variations

Like a normal knee, the prosthesis has smooth weight-bearing surfaces. Many types of designs and materials are used in TKR procedures. Most implants consist of three parts: a femoral component made of a highly polished strong metal; a tibial component made of a durable plastic, often held in a metal tray; and a plastic patellar component. During surgery, the patella is moved aside and the ends of the femur and tibia are cut to fit the prothesis. The two parts of the prothesis are placed into the ends of the femur, the tibia and the undersurface of the patella, most often secured with a special bone cement.⁶ People with severe OA in both knees may be candidates for bilateral TKR. However, a bilateral procedure increases surgical risk. Two types of fixative hold the knee prosthesis in place. Cemented designs use a fast-curing bone cement to hold the prosthesis in place and allow immediate postoperative weight bearing as tolerated. Cementless designs are coated or textured so that new bone actually grows into the surface of the implant. Because joint stability depends on new bone growth, cementless knee replacements take longer to heal than do cemented versions.^2,12 Combined with advances in surgical techniques and new materials, cementless knee replacements may have the potential to increase the life of the prothesis and thus to delay the expense and risk of revision surgery.^2,13

Once she decided to have joint replacement surgery, Mrs. Richter donated 2 units of her blood for use during or after surgery if needed and attended a three-hour class at the hospital. The class helped her understand what would be done during the surgical procedure, what to expect after surgery and what exercises to do both before and after surgery to strengthen the muscles around her knee joint. Mrs. Richter had a lot less pain than she expected after surgery. She described it as resolving muscle pain rather than the chronic bone-rubbing-on-bone pain she felt before surgery. Mrs. Richter now goes up and down stairs and is beginning to play tennis again.

The majority of people who have a total knee replacement have a dramatic reduction in their knee pain and a significant improvement in their ability to perform ADLs. Improvement of knee motion is a goal of total knee replacement, but restoration of full motion is uncommon.

Most patients can expect to fully straighten the replaced knee and to bend the knee sufficiently to go up and down stairs and to get in and out of a car.⁴ Most people may resume driving several weeks after surgery. Patients should have realistic expectations for total knee replacement.⁵ In fact, part of preoperative education for patients having total knee replacement is to understand that there are some activities, such as jogging and high-impact sports, that they need to avoid for the rest of their lives to protect their new, pain-free joint.^5,11

Accurate alignment of the femoral and tibial components of the knee replacement must occur to meet the goals of knee stability, decreased postoperative pain and complications, and a long life for the prosthesis.¹⁴ Computer-assisted surgery provides some important benefits during total knee replacement. It can help ensure accurate alignment and fit of the prosthetic components. Some experts believe that computer-assisted surgery systems will transform orthopedic surgery in the next few years by offering more accurate, less invasive joint surgeries with less pain and faster rehabilitation.¹⁴

How long an implanted prosthesis lasts varies with the patient’s age, weight, and activity level. With appropriate activity modifications, knee replacements last for many years.⁵ Before the initial total hip replacement or total knee replacement, the possible complications of loosening of the joint prosthesis is discussed with the patient. The patient learns strategies to prolong the life of the prosthesis, such as maintaining ideal body weight and avoiding activities that place excess stress on the joint. Because greater numbers of younger people are having joints replaced, revision surgery is becoming more common. Revision surgery is more complex than the original surgery, and the results may not be as successful.^9,15

A Success Story

Continuing improvement in artificial joint design and surgical procedures has greatly increased the success of total joint replacement. Total joint replacement generally provides greater mobility and decreases pain for patients when medications and physical therapy cannot manage symptoms. One recent study showed that younger age and male gender are associated with an increased risk of joint revision surgery, mortality is higher in older men than in women and younger patients, and functional gains are less in older people.¹⁶

By understanding the basis of the arthritic changes that damage hips and knees, recognizing indications for total joint arthroplasty and reviewing the surgical procedures used, physical therapists can assess individual patient needs and provide care that will help patients achieve a successful, pain-free outcome.

Gannett Education guarantees this educational activity is free from bias.