The lifetime risk of a serious infection after a knee replacement is approximately 1%. Some of these infections occur soon after surgery, but most occur months or years afterwards. The treatment for serious (deep) infections includes revision surgery and IV antibiotics. Skin infections (cellulitis) after knee replacement is more common and can be treated with oral antibiotics.
People at higher risk for infection include patients with poorly controlled diabetes, patients with morbid obesity (BMI more than 40), patients who are immunocompromized (eg HIV, lymphoma), or are taking immunosuppressant drugs, patients with peripheral vascular disease (poor circulation to hands and feet) and smokers. An ongoing infection at the time of surgery from another source (eg active urinary tract infection, tooth abscess, diabetic foot infection can increase your risk of infection after surgery.
In order to prevent infection, your surgeon will give you one dose of antibiotics through your IV in the operating room before your surgery. You will get one more dose after your surgery. Growing evidence suggests that numerous doses of antibiotics after your surgery does not prevent infection.
The symptoms of infection include fevers, redness around the wound, persistent leaking from the wound, increasing pain in a previously well-functioning joint replacement. If you think you are developing an infection around your knee replacement, call your orthopaedic surgeon’s office as soon as possible or go to your nearest emergency department.
Most patients experience a patch of skin numbness, about the size of their palm just to the outside of (lateral to) the incision site of the knee replacement scar. This patch of skin numbness can decrease in size over months to years, but will not affect your function.
Incomplete pain control
Knee replacement can help with 80-85% of knee pain associated with arthritis after 3 months of recovery, but doesn’t usually get rid of 100% of knee pain. Most people still get some aches and pains in their knee replacement, even after recovery is complete.
Immediately after total knee replacement, your knee will be stiff and painful to move. It is of the utmost importance to work on moving your knee despite this discomfort in the first few days after your knee replacement. Doing the exercises given to you by your physiotherapist immediately after your surgery will help you enjoy your knee replacement in the long run. If you do not work on bending and straightening your knee after your surgery, your knee replacement can become permanently stiff. Ideal range of motion after knee replacement recovery is 0 (completely straight) to 120 degrees. After surgery, it is unlikely you will be able to squat all the way down such that your heel touches the back of your thigh.
Some blood loss during knee replacement is normal. Blood loss requiring a blood transfusion after surgery is rare unless you are anemic (low hemoglobin levels) before surgery. You will be sent for blood work when you book your surgery to make sure that you are not anemic. If you are anemic before surgery, we will refer you to our Patient Blood Management Coordinator who may suggest ways to build up your hemoglobin levels prior to your surgery. The risk of requiring a blood transfusion increases if you are having both your knees replaced at once.
Blood clots in leg veins can occur after knee surgery. Your surgeon will prescribe a medication for you to take after your surgery in order to prevent blood clots. If a clot develops in a deep leg vein (deep vein thrombosis – DVT) above the knee, it will need to be treated with stronger blood thinners. Above knee DVTs need to be taken seriously because they can cause clots that go to the lungs (pulmonary embolus), which is a very serious condition. If you have previously had a DVT, please let your surgeon know prior to your surgery.
The metal components of the knee replacement are usually cemented to your bone during a knee replacement. Over the years however, the bond can loosen, requiring a revision of the components. Less common causes of early loosening include infection, morbid obesity and severe osteoporosis.