If you are deciding and want detailed information about knee replacement surgery… we have the answers for you.
Q: How many years does a knee prosthesis last?
A: According to statistics, the chance of a knee prosthesis loosening within 10 years is about 2-5%. The chance of loosening within 20 years is about 10-15%, and the chance of lasting more than 20 years is about 80%. This depends on several factors.
- The patient’s usage
- The expertise of the orthopedic surgeon
- The quality of the prosthesis
The important factors affecting the lifespan of the prosthesis, about 80%, depend on points 1 and 2. What patients who undergo knee replacement surgery should do is to maintain their weight without gaining too much, avoid squatting unnecessarily, avoid long-distance running, and avoid contact sports such as football. If you take good care of yourself, exercise regularly, avoid prolonged infections anywhere in the body, and do not neglect dental caries, gum inflammation, urinary tract infections, or foot nail wounds, these good factors will help the knee prosthesis last longer.
Q: Are expensive knee prostheses more durable than cheaper ones?
A: A high price does not always indicate good quality. The prosthesis must fit the knee anatomy and the balance of the surrounding tissues. Many expensive prostheses, if not properly fitted to the patient’s knee, may not last long.
Q: Will knee replacement surgery make the leg shorter?
A: The leg will not be shorter but will appear longer compared to before surgery because the operated leg will be straighter. Bowed legs make a person appear shorter. If both legs are bowed, the non-operated leg will be shorter.
Q: What are the reasons that prevent knee replacement surgery?
A: General illnesses such as dental caries, cough, cold, or shingles should be treated before surgery because the body must be in the best condition on the day of surgery. Patients with diabetes, heart disease, or high blood pressure, although incurable, must have these conditions controlled within normal limits before surgery. Blood sugar should not exceed 150 mg/dL, blood pressure should not exceed 140-150 mmHg. Heart patients must be tested and consult a cardiologist to determine if surgery is possible. If the risk is high, surgery should be postponed until the heart condition is stabilized.
Contraindications include severe infection on the day of surgery. Surgery should not be performed if there is an infection around the knee or elsewhere in the body; surgery should be postponed. Other conditions where surgery is not recommended include patients with paralysis or hemiplegia who have no muscle strength, as surgery will not enable walking. Muscles may be fibrotic and unable to bend or straighten, or nerves supplying the muscles may be damaged.
Q: Can patients with spinal nerve compression undergo knee replacement surgery?
A: They can undergo knee replacement surgery. Moreover, the surgery may help improve the condition.
Q: Will metal knee prostheses act as lightning rods?
A: The answer is no. Prostheses are made from special metal alloys such as titanium, cobalt-chromium, or ceramic, which do not react with electricity. They are also strong and durable, allowing you to walk in the rain.
Q: Can patients with osteoporosis undergo knee replacement surgery?
A: They can, but special caution is needed because during surgery, fragile bones may break more easily than normal bones, and post-surgery there is a risk of fracture. Additionally, the prosthesis must be chosen to suit the bone and properly balanced. The tension of the tissues around the knee must be strong and stable. After surgery, patients should have further examinations and treatment for osteoporosis.
Q: Are there any dietary restrictions after knee replacement surgery?
A: You can eat everything except patients with pre-existing conditions such as gout must control foods that trigger symptoms. Diabetic patients must control starch and sugar intake. Patients with knee replacements should be careful to control their weight and avoid excessive gain.
Q: How does knee bending before and after knee replacement surgery compare?
A: The range of knee bending after surgery depends on many factors. The most important is the degree of knee bending before surgery. If the patient allowed the condition to worsen until the knee could not bend before surgery, after surgery the bending may improve by only about 20%. If the patient still had a chance to fully bend before surgery, the chance remains high. It also depends on the surgeon’s ability to balance the knee and choose the appropriate prosthesis size. Prostheses designed for greater bending can help somewhat but not significantly. Another factor that helps increase knee bending and straightening is physical therapy and self-training after surgery. Consistent and diligent practice will help improve knee movement.
Q: How long does the surgery take?
A: Each patient varies depending on the severity of their condition and the surgeon’s expertise. On average, it takes about 1-2 hours.
Q: How long is the recovery period after surgery?
A: Usually about 24-48 hours after surgery, the team will encourage the patient to get up, sit, stand, practice using the bathroom independently, and walk around the room. Patients will practice going up and down 5-10 steps before going home. On average, patients stay in the hospital about 5-7 days and can return home able to care for themselves.
Q: What is the maximum age for patients undergoing knee replacement surgery?
A: Health and physical strength are more important than age. Patients over 90 years old have undergone knee replacement surgery because they are still strong and able to care for themselves. If general health is good, surgery is possible.
Q: Has there been a case of simultaneous bilateral knee replacement surgery?
A: It depends on the conditions. The patient’s general health must be strong to safely undergo bilateral knee replacement surgery, such as no severe diseases like uncontrolled heart disease, diabetes, or hypertension. The medical team must be experienced to manage the surgery time appropriately, not too long. There must also be a physical therapy team for care, and the anesthesia and medical teams must monitor the patient during and after surgery promptly and expertly to ensure safety.
Q: Can knee and hip replacement surgeries be done simultaneously?
A: Simultaneous knee and hip surgeries are sometimes done but are not common because each surgery is major. Usually, simultaneous surgeries involve both hips or both knees. It is uncommon to have both hip and knee osteoarthritis at the same time.
Q: Why is there numbness around the surgical wound?
A: After surgery, numbness around the wound may occur due to temporary loss of sensory nerve function. This is harmless and usually resolves within the first 3 months.
Q: Why does the leg swell after surgery?
A: It is usually caused by slower venous return to the heart due to reduced muscle contraction in the leg. Elevate the leg while sitting or lying down to relieve swelling. If swelling is excessive or accompanied by pain, watch out for deep vein thrombosis.
Q: What is the maximum knee bending angle after knee replacement?
A: After knee replacement surgery, the knee should bend at least 90 degrees. If stiffness is more than usual, consult a doctor.
Q: Why is there a clicking or crunching sound when moving the knee?
A: After knee replacement surgery, clicking or crunching sounds may occur when bending or straightening the knee. This is the sound of the kneecap contacting the prosthesis and is normal. However, if the sound is loud and painful, see a doctor immediately as it may indicate a problem such as improper prosthesis alignment or ligament tear.
Q: Self-care and knee prosthesis care after surgery
A:
- Control weight to avoid excessive gain
- Exercise to strengthen muscles, such as swimming, cycling, golf, dancing (but do not overexert). Avoid contact sports and high-impact activities like football and long-distance running
- Avoid squatting, crossing legs, sitting on heels, or sitting on low chairs unnecessarily
- Maintain personal hygiene
- Avoid lifting heavy objects
- Attend regular follow-up appointments
Q: What complications may occur after surgery?
A: Infection occurs in about 1-2% of cases. Hematoma may sometimes occur. Wound separation, deep vein thrombosis in the leg, knee instability, torn blood vessels, nerve injury, urinary tract infection, respiratory problems, and death from various complications.
Q: How to prevent infection?
A: Within 2 years after knee replacement surgery, if dental work or cystoscopy is necessary, patients should receive antibiotics before the procedure. For any other medical procedures such as eye surgery or gastrointestinal surgery, patients should also receive antibiotics to prevent knee infection, depending on the treating physician’s judgment.
Q: How should exercise be performed after surgery?
A: Phase 1: While lying in bed
- Exercise 1: Move the foot up and down at least 20 times every 30 minutes
- Exercise 2: Lie on your back, straighten the knee, tighten the leg against the bed, hold for a count of 1-10, and repeat continuously for at least 10 minutes
Phase 2: When able to sit up
- Exercise 1: Sit dangling legs, place the non-operated leg down, lift and tighten the operated leg, move it up and down 20 times per session, 3 sessions per day
- Exercise 2: Sit dangling legs, press the operated leg close to the bed edge, 20 times per session, 3 sessions per day (or as much as possible)
- Exercise 3: Sit dangling legs, straighten the knee, dorsiflex the foot, tighten and hold for a count of 1-10, then lower the foot, count as 1 repetition, 20 times per session, 3 sessions per day
Q: What is the correct posture for sitting, walking, and standing after surgery?
A: Using a walker from sitting to standing: Sit upright, move the walker close to your body, step the operated leg forward slightly ahead of the other leg, then lean forward slightly. Hold the walker firmly with both hands and slowly bring the other leg forward to align.
Using a walker from standing to walking: Move the walker forward moderately, step the operated leg forward, then step the other leg to align both feet.
Going up stairs: Stand upright holding the handrails with both hands. Step up with the less painful or non-operated leg first, then bring the other leg up to the same step. Continue until reaching the landing.
Going down stairs: Stand upright holding the handrails with both hands. Step down with the operated or more painful leg first, then bring the other leg down to the same step. Continue until reaching the floor.
Using the bathroom sitting on the toilet: Stand upright facing the toilet, slowly move the non-operated or less painful leg first, then step the other leg forward while moving the walker back. Continue stepping back until both feet touch the toilet, then step the operated or painful leg forward and slowly bend forward to sit down on the toilet.
Using the bathroom standing up from the toilet: Move the walker close, hold the walker or grab bars for support, step the operated leg forward followed by the other leg, lean forward and slowly stand up straight, then step the other leg forward to align and walk out of the bathroom.
Muscle, Bone, and Joint Center, Phyathai 3 Hospital We provide systematic care for all patients with a team equipped with knowledge, understanding, and specialized expertise with extensive experience. Our team includes orthopedic surgeons specializing in joint replacement, nurses, physical therapists, nutritionists, and pharmacists who are ready to care for patients before and after surgery to enhance treatment effectiveness and help patients regain good joint function.
