Hip and Knee Joint Replacements and Recovery
By Nina Clark, CSCS
Introduction to a total joint Replacement:
Today over 760,000 Americans undergo joint replacement surgery in one form or another each year (AAOS Department of Research and Scientific Affairs, 2002). According to the American Academy of Orthopedic Surgeons 52% of surgeries in 2002 were knee replacements and 45% were hip replacements (AAOS Department of Research and Scientific Affairs, 2002). Hip and knee replacement can last 20 years in 80% of people who undergo the surgery (Bren 2004). The majority of the population who receive total joint replacements are between the ages of 60-80. However, it is becoming more common for younger people to receive joint replacements.
The wear and tear on a joint is similar to that of a tire. The time it takes to wear out a tire is dependent on the frequency, millage, and terrain that it is driven on; how heavy the vehicle is and how well the vehicle is maintained. This applies to joint health both before and after replacement. The decision to undergo a surgery must be made with careful consideration and knowledge of the risks and benefits and with the guidance of a physician.
Brief Anatomy and Classification of a Joint:
A joint is made up of two or more bones that come together and are connected by strong fibrous tissue. The joint allows smooth movement to occur between the bones and absorbs the shock from repetitive movements. Joints are made to withstand repetitive movements in an effective and smooth manner. Joints are classified by the way the bones articulate with one another and the type of movement they allow. We will look at two classifications Ball in Socket Joint (hip) and Hinge Joint(knee).
The hip and shoulder are examples of ball in socket joints. Both have long bones with rounded heads (head of the humerus and head of the femur) that articulate with the smooth shallow portion of the scapula or pelvis. This type of articulation and joint allows for the greatest amount of movement.
The knee and elbow are examples of a hinge joint. This joint has a convex bone surface that fits into the concave portion of another bone, like a hinge on a door. The hinge joint allows for only one plane of motion to occur: flexion and extension.
Both the ball-and-socket and hinge joints are examples of synovial joints. On either ends of the bones there is a layer of cartilage. Cartilage is a slippery protein coating which cushions and aids in shock absorption. Covering the outside of the joint is a strong membranous capsule that keeps the bones in close to one another. Inside the capsule is a smooth, thin lining called the synovium, which secretes fluid to reduce friction and degeneration inside the joint. Synovial fluid lubricates the joint and is a source of nutrition for the cartilage. The other structures that keep the joint stable include ligaments, tendons, and muscles. Ligaments are tough tissue connecting one bone to another, and tendons connect muscle to bone. Muscles are strong bands of tissue that contract and produce movement in the joint. Together the ligaments, tendons and muscles stabilize the joint and allow it to move through its full range of motion.
Problems that Occur in the Joint
There are several different causes for joint pain:
- Rheumatoid Arthritis – a systemic autoimmune disease characterized by the inflammation and thickening of the joint space. In chronic conditions it can lead to cartilage loss, pain, and stiffness.
- Post-Traumatic Arthritis – results from a previous bony fracture or when a ligament tears from a injury which can lead to early degeneration of a joint as well as pain and limitations in movement.
- Osteoarthritis – a degenerative joint disease that causes destruction of a joint, resulting in pain, and impaired movement. There are no definite answers for what causes the disease, but researchers believe that it includes a number of factors including joint stress, previous injury, the aging process, and being overweight.
As the disease progresses the cartilage begins to wear away and the bones begin to rub against one another causing inflammation and pain. This pain often is a result from pressure on the nerve endings, muscle tension, and fatigue. This causes a very limited range of motion and increased weakness of the lower body muscles which then in turn cause decreased mobility and conditioning of the body often resulting in a more sedentary lifestyle. There are ways to treat and manage osteoporosis in its premature stages.
Exercise, including physical therapy, occupational therapy, and personal training, is very helpful to improve muscular strength to support the muscle, flexibility, reduce body weight, decrease pain, and improve psychological well-being. Strength training using low weights and multiple repetitions helps improve muscular strength and the support of the joint. This is important in order to return to functional activities.
Aerobic exercise can improve function of the circulatory system and respiratory system. Flexibility training can improve the range of motion of the joint. Medications such as anti-inflammatory or other pain relieving drugs can be very helpful in reducing pain and swelling in the joint. Rest and activity modification will also reduce the amount of stress placed on the joint. Surgery is the last resort in helping to stop osteoarthritis from progressing.
