Knee Replacement

Introduction

The purpose of this handbook is to give you an overview of total knee replacement surgery.  It will give a history of  knee replacements, explain the working of your knee joint and explain when surgery is needed.  You will learn about what to expect while in the hospital both before and after surgery, and how we will help you return to a normal life style at home.

The Knee

The knee is the largest joint in the body.  It is commonly referred to as a “hinge” joint because it allows the knee to flex (bend) and extend (straighten).  While hinges can only bend and straighten, the knee has the additional ability to rotate (turn).  The knee joint is formed by the tibia (shin bone), the femur (thigh bone), and the patella (knee cap).  Each bone end is covered with a layer of smooth shiny cartilage which cushions and protects it allowing for easy, frictionless motion.  Cartilage contains no nerve or blood supply and receives its nutrition and lubrication from the fluid contained within the joint, the synovial fluid.  It is also not capable of reproducing itself.  Surrounding the knee joint is the synovial lining, which produces the synovial fluid.  Tough fibers, called ligaments, connect the bones of the joint.  They help stabilize and control the joint during motion.    Muscles and tendons, which attach muscle to bone, move the joint and also play an important role in keeping the joint stable.

When Joint Problems Arise

The development of total knee replacement began over 20 years ago.  Today, over 300,000 people in the U.S. annually undergo knee joint replacement surgery as a means of diminishing pain and stiffness, and restoring mobility.

The most frequent source of debilitating pain is arthritis.  It is estimated that 37 million people in the United States have some form of arthritis.  That’s one in every seven people, one in every three families.  Of the more than 100 types of arthritis, the following three are the most common forms causing joint damage.

Osteoarthritis, commonly termed degenerative arthritis, is a disease that involves the breakdown of tissues that allow joints to move smoothly.  The layers of cartilage and synovium become damaged and wear away leaving the bone joints unprotected from wearing against each other.  It occurs primarily in people over 60.

Rheumatoid arthritis, is a systemic disease that may attack any or all joints of the body.  It affects women more often than men and can strike young and old.  It causes the body’s immune system to produce a chemical which attacks and destroys the protective cartilage and the joint surface.

Trauma-related arthritis, which results when the joint is injured, is the third most common cause of arthritis causing joint damage, pain and loss of mobility.

Pain, stiffness, knee swelling and limitation of motion are some of the symptoms which are experienced with arthritis.  As cartilage deteriorates it cannot be replenished, so progressively the arthritis becomes worse.  The end result is the loss of cartilage over the ends of the bones eventually leaving nothing but bone-on-bone contact.  You may also notice the alignment of your leg becoming progressively knock-kneed or bow-legged.  If your x-rays show severe destruction of the joint, you must decide if the degree of pain you experience, and the loss of use is severe enough that you are prepared to undergo an operation. When conservative methods of treatment fail to provide adequate relief, knee replacement is considered.

Today, your orthopaedic surgeon can replace your problem knee thanks to technology which has been developed and proven to provide long-term relief.  Knee joint replacement is a remarkably successful operation that has transformed the lives of many people.

Total Knee Replacement

Total knee replacement or “arthroplasty’ is the resurfacing of the joint (bone end surfaces) with artificial parts called prostheses.  There are three components used in the knee.  The femoral (thigh) component is made of metal, and covers the end of the thigh bone.  It may be cemented to the bone, or inserted without cement.  When it’s implanted without cement, the component will become biologically fixed when bone grows into the rough surface on the device.

The tibial (shin bone) component, made of metal and polyethylene, covers the top of the shin bone.  The metal forms the base of this component and is in direct contact with the shin bone.  The polyethylene is inserted on top of the metal and serves as a cushion and a smooth gliding surface between the metal of the femoral and the metal of the tibial components.  The tibial component may be secured to the bone with bone cement, or biologically fixed.

The third component, the patella or knee cap, is all polyethylene.  This component is inserted with cement.

The total knee replacement is inserted through an incision that runs three or four inches above the knee cap to several inches below the knee.  The new components are stabilized by your ligaments and muscles, just as your original knee was.

 

Unicompartmental Knee Arthoplasty

Unicompartmental knee replacement is the resurfacing of one of the three “compartments” of the knee, the inside (medial compartment), outside (lateral compartment), or front (patello-femoral compartment) of the knee. The artificial parts, prosthesis, are fixed to bone with cement in most cases.  The femoral component is made of metal.  The tibial component is made of metal and plastic. The Unicompartmental prostheses are inserted through an incision usually half the length of what is needed for a total knee arthroplasty.

The arthritis has to be mostly limited to one compartment, usually either the medial (inside) or lateral (outside).  The patient’s complaints must be limited to only one area of the knee. The ligaments must be intact and without contracture. The patient must understand that this procedure should last about 10-15 years. There will be fewer limitations of activities compared to either a Total Knee Arthroplasty or a Unispacer. 

PREPARING FOR SURGERY

Your Medical Evaluation

Patients must have a physical exam by their family doctor, internist, or surgeon before surgery.  After your physical exam, your doctor will schedule you for pre-admission testing that will take place about one or two weeks before your surgery.

The pre-admission test will provide your physicians with vital information about your health.  You will need to bring your insurance information including referral forms and insurance cards at this time.  During your pre-admission test you will undergo an electrocardiogram (E.K.G.) which measures the activity and health of your heart.  Other tests may include x-rays and blood and urine tests.  It is important that you inform the medical staff of recent illnesses including colds, sore throats, or flu.  If you have dental problems, please report them at this time.  To prevent the risk of infection, dental work may need to be postponed or scheduled at least two weeks prior to your surgery.  Please discuss this with the medical staff.

Blood Donation

You may need a blood transfusion after surgery.  If you have any questions, please discuss this with your physician.

 

Admission to the Hospital

The day before your scheduled surgery, a representative from the hospital’s admissions office will phone you.  They will tell you what time to arrive at the hospital (about 3 hours before your scheduled surgery) to complete your admissions paperwork.  The evening before surgery, you will be reminded not to eat or drink anything after midnight.

What to Bring to the Hospital

What to Expect the Day of Surgery

Family Friends

The surgical lobby is located near the pre-surgical area, operating rooms, and recovery room.  Your family should inform the staff of their arrival in the area and keep the staff posted of their whereabouts at all times.  They may allow you to see you before you go back for surgery. After you go into the operating room, they will be directed to the waiting area.  The surgeon will speak to them following your surgery.  It is common for the patient to be away from the hospital room approximately four to five hours including the recovery room time.

 

After your Surgery: The Recovery Room

You will awaken after your surgery in the Post-Anesthesia Recovery room.  You will remain there until you have recovered from the anesthesia, are breathing well, and your blood pressure and pulse are stable.  There may be some reactions to the anesthesia such as nausea, dizziness, sleepiness, etc.  If you have pain, the specially trained nurses will administer medication.

What to Expect After Surgery

You will have a drainage tube coming through the surgical dressing which is attached to a collection apparatus that will be removed two days after surgery.  This system provides gentle continuous suction to remove any blood that accumulates in the surgical area.  Some of this blood will be given back to you.  In two, or three days, the dressings will be changed.

When in bed, your leg will be supported and elevated on one or two pillows to help your circulation and to stretch the muscles behind your leg.  You will be asked to move your ankle to promote good circulation and prevent stiffness in your ankle joint. 

During your hospital stay your operative leg may be placed into a “Continuous Passive Motion” (CPM) machine.  Your leg is held in a cradle and gently taken through slow bending and straightening movements.  Try to use your muscles to help the CPM machine straighten your leg.  Try to increase the bend as much as you can tolerate.  The nurses can help you increase the bend of the machine.

The nurse will assist you in turning on your side if you wish.  You may adjust the head of the bed to any level you desire.

An intravenous (IV) line will remain for one or two days to administer antibiotics.  This helps prevent infection, and gives you proper nourishment until you are eating and drinking comfortably.  You may begin drinking and eating your meals as you like, under the direction of your surgeon.

To prevent fluids from building up in your lungs, you will receive an incentive spirometer after surgery to encourage you to cough and breathe deeply.  This is used every hour while you are awake.

It is normal to feel pain and discomfort after surgery.  The nurse should be informed of your pain and medication will be given.

Possible risks that may occur with knee replacement include

 

Physical and Occupational Therapy

Your knee rehabilitation program begins the day of surgery and is ordered by your surgeon.  Isometric exercises (tightening muscles without moving the joint) will begin while you are still in bed.  These should be done 10 times per day while awake.  You will be encouraged by your physical therapist and nurses to move your ankle and other joints so that you will remain strong, and move about more easily.  (For more details, refer to the section in this handout titled “Exercises.”)

These exercises will help you regain strength and mobility.  Your therapist will teach you the safest methods for getting in and out of bed or a chair, and on and off the toilet.  You will be taught the do’s and don’ts of joint replacement recovery.

Initially, the physical therapist and nurses will assist you out of bed to stand at the bedside with a walker.  For your entire hospital stay, you will walk two times each day with a walker, crutches, or a cane supervised by your therapist.  Your walking distances will gradually increase.

Through daily progressive exercises, you will achieve about a 90-degree angle in the knee joint by the time you leave the hospital.

Bending your knee during the exercises can be painful.  Pain medication should be taken before therapy which will make the exercises more comfortable.  Ice packs, hot packs and other modalities may also be used to assist you in bending your knee.  Your therapist will check your progress in therapy daily and will keep your surgeon informed.

After discharge from the hospital, you will need to continue therapy.  You must arrange therapy three times a week for up to six weeks after surgery.

Progress

The usual stay in the hospital for total knee joint replacement is two to four days. For the Unicompartmental knee arthroplasty and the Unispacer the stay in the hospital is about 1-2 days.  To accommodate your sitting, there will be a high chair and elevated commode available for you use.  We will order an elevated commode for you to take home.  At home you will need a firm chair with arms that you can use.

Your therapist will teach you how to dress, get out of bed without help, and use a walker or crutches.  You will continue strengthening yourself in preparation to return home.

It is important for you to adhere to precautions and proper positioning techniques throughout your rehabilitation.  Your stitches/staples will be removed ten to fourteen days after surgery.  It is not uncommon to still experience pain.  Expect your recovery period to last three to six months.

Preparing to go Home

Just prior to your discharge, you will receive instructions from one of the surgeon’s nurses. Until you are told differently you must take certain activity precautions.

As soon as you are home from the hospital, make a follow up appointment six weeks after the surgery, if not already scheduled.  (You need to make an appointment for 10 to 14 days after surgery, if you leave the hospital with staples and you don’t already have one.)

Look for any changes around your incision.  Contact your surgeon if you develop any of the following:

 

Take time to adjust to your home environment.  It is normal to feel frustrated but these frustrations will soon pass.  It is okay to take it easy.

Resuming Activities

Depending upon the physical demands of your job, work may be resumed when authorized by your surgeon.  Driving may be resumed once you have attained full weight-bearing.  Be sure you are comfortable with your strength.  Be sure to practice driving in a safe area.  Once you are comfortable with your mobility, you may drive elsewhere.

Sexual intercourse may be resumed at any time.  Always remember the knee precautions.

We encourage you to be active in order to control your weight and muscle tone.  It is generally three to four months before you can resume low-impact aerobic activity such as walking, golfing, bowling and swimming.  Jogging, high-impact aerobics and contact sports are never allowed.  Your new knee is artificial and although made of extremely durable materials, it is subject to wear and tear.

 

Medication/Pain Control

It is normal for you to have some discomfort.  You will receive a prescription for pain medication before you go home.  If a refill is needed, please call your surgeon’s nurse at least 5 days before you run out of pills.  Please contact your surgeon if you have an increase in discomfort or pain.

We will not refill medications after office hours or on weekends.

 

Exercises

Regardless of your age, it is now necessary to regain strength in the muscles which surround your joint.  Your muscles power your knee to move.  Good muscle strength will help you to walk, climb stairs and get up from a chair.  Since your knee had caused you pain, you probably had reduced your walking and exercising before surgery.  Although this was necessary to avoid pain in your knee, the muscles that were not used regularly have become weakened.  Please do your exercises daily as instructed by your therapist.

ADDITIONAL INFORMATION IS AVAILABLE AT THE FOLLOWING WEBSITES:

 

www.aaos.org

Written by James A. Shapiro, MD