Knee Joint Replacement Overview
The procedure of knee joint replacement is called a total knee arthroplasty (TKA). This surgery involves replacing your knee joint with a manmade one. Doctors may replace your knee joint to end pain, stiffness, and loss of function.
Knee Joint Replacement Causes
Both chronic osteoarthritis and rheumatoid arthritis commonly cause people to lose knee function to the degree that they need a knee joint replacement (total knee arthroplasty or TKA). But knee damage may also stem from injury or infection. Generally, people require a TKA a decade earlier due to rheumatoid arthritis as opposed to osteoarthritis.
* The most common problems with a knee joint replacement
o Fractures (breaks) of the new knee after a fall or other accident
o Pain from slippage and wear in the new joint
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* Other less common problems
o Infection of the joint
o Dislocation, either complete or partial, of the new knee
o A blood clot in a vein (deep venous thrombosis) above or below the knee (Clots occur most commonly shortly after replacement surgery.)
Knee Joint Replacement Symptoms
* Many people who fall after having a knee replacement break the bone below the new joint on which the new knee is anchored. Pain and swelling occur at or near the site of the knee joint replacement.
* Pain can occur gradually as the new joint develops wear patterns that interfere with the smooth function of your knee.
o Slippage can cause bony surfaces to move opposite each other and cause pain.
o This pain increases the more steps you take and decreases when you sit.
o This pain of movement differs from the normal start-up pain that occurs in the first 3-6 months after knee replacement and that decreases over the first few steps.
o Infection will cause pain, along with frequent redness and swelling at the joint, even when you are at rest.
o Often fluid will collect at the knee joint from infection and cause a boggy swelling. Fluid may not accumulate with every infection.
o Fever may occur.
* Dislocating the knee will cause pain.
o Deformity of the joint will be obvious.
o A dislocation may damage adjoining nerves, muscles, and blood vessels and impair their function. The popliteal artery, which carries the entire blood supply to your lower leg and foot, can be injured or pinched shut. Nerves to your lower leg can be cut or injured, causing your lower leg to become numb (paresthesia), weak (paresis), or paralyzed. Arteries can be partially or totally blocked, eventually causing pain, the lower leg to turn pale and cold, poor or no pulse, and the leg to swell.
o Blood clots tend to form during the period ("post-op," or "post-operatively") when you cannot move following a knee replacement.
+ Clots become progressively less common with time.
+ A clot in your vein generally causes new pain, swelling, or redness in your lower leg.
+ The greatest concern is that the clot will travel through your veins and could lodge in your lung (pulmonary embolism).
When to Seek Medical Care
Call your family doctor or orthopedist if you develop gradual pain that feels like slippage in your knee. This generally is an urgent problem, but not an emergency.
Call your doctor if you notice unexpected drainage from or poor healing of a recent surgery, increasing swelling, or warmth.
Go to the hospital’s emergency department if you experience any of the following:
* A fracture or dislocation after a fall
* New swelling
* New pain while resting
* Redness, or warmth at a joint suggesting infection
* Swelling, pain, or redness below your knee that suggests a clot in your vein (deep venous thrombosis or DVT)
Exams and Tests
Your doctor will base your diagnosis on clinical examination and x-rays.
* A fracture usually involves a bone directly above or below your new knee. Most commonly your thigh bone (femur) breaks just above its connection with the knee replacement.
* As the new joint begins to wear, your knee may not glide smoothly through its range of motion. You likely will notice that movements are painful now that were not painful in the past.
* Pain from infection does not go away with rest, and fluid may begin to build up in the knee joint.
o The doctor can sample any fluid through arthrocentesis, a procedure of drawing the fluid out with a needle and syringe.
o Blood tests also may be performed.
* An x-ray can confirm a knee dislocation. A doctor must assess any damage to nerves, blood vessels, or muscles besides the dislocation itself.
* A blood clot often causes pain and swelling in your leg farther from your heart than where the clot sits. That area may become red and feel warm.
o Your doctor may perform a Doppler ultrasound test, especially for a clot suspected to be above your knee. This evaluates the flow of blood in that area.
o The doctor may also order a venogram of your leg. In this test, dye is injected into a vein, and x-rays are assessed to look for evidence of a blood clot in a deep vein of the leg. Without the dye, the veins would not show up on an x-ray.
Self-Care at Home
Follow your prescribed physical therapy program carefully to rehabilitate your new knee joint.
Because your total knee arthroplasty (TKA) is a substitute (prosthetic) device, it can become infected when bacteria enter the blood. Doctors commonly prescribe antibiotics when you have other surgery, such as dental work, invasive tests, or surgery elsewhere on your body.
