Total Knee Replacement: Frequently Asked Questions
1. What is a Total Knee Replacement?
A total knee replacement is a surgical procedure designed to eliminate arthritis from the knee. Arthritis of the knee occurs when there is a loss of the cartilage in the knee and there is bone-on-bone.
The procedure entails making a longitudinal incision in the front of the knee starting from the top of the patella and extending to the tibial tubercle. An incision is then made in the deep capsule in order to enter the knee joint. The entire articular surface of the knee is then exposed, bone spurs are removed, and special jigs are used to make small cuts in the bone to remove all of the cartilage. The cuts that are made in the bone are designed to restore the normal alignment of the knee and to correct any varus (bowlegged) or valgus (knocked knee) deformities. The cuts in the bone typically do not alter the leg length of the extremity. Care is taken to protect and preserve the ligaments on the inside and outside of the knee (MCL and LCL). Once the cuts had been made, trial total knee components are then placed onto the femur and onto the tibia and a polyethylene spacer is placed between the two metal components. The knee is then brought through a full range of motion to make sure that the knee will come to full extension and also will be able to fully flex. The knee will also be checked to make sure that all of the ligaments are stable around the knee. Once the appropriate component sizes are found, the real components are then placed in utilizing bone cement.
The wound is then closed using absorbable sutures that are buried underneath the skin so that no sutures need to be removed when the patient returns to the office.
2. What are the indications for a Total Knee Replacement?
Typically, a total knee replacement should not be considered until other conservative treatments have been first utilized. Treatments include activity modification, weight reduction is indicated, nonsteroidal anti-inflammatory medicines, corticosteroid injections, Visco supplementation injection, and possible braces. As a general rule, a total knee replacement may be indicated if there are signs of advanced degenerative joint disease that is seen on x-ray, clinical exam findings of pain over the same area, conservative treatments have failed to provide adequate pain relief, there are no other sources of pain (i.e. back pain with sciatica), and the pain is effecting the patient’s quality of life. A patient’s age is also a determining factor as to when a knee replacement should be performed.
3. When should I have a Knee Replacement done?
As a general rule, a total knee replacement may be performed if there are signs of advanced degenerative joint disease that is seen on x-ray, clinical exam findings of pain over the same area, conservative treatments have failed to provide adequate pain relief, there are no other sources of pain (i.e. back pain with sciatica), and the pain is effecting the patient’s quality of life. A patient’s age is also a determining factor as to when a knee replacement should be performed. It is preferred for a patient’s age to be over 60 years of age in order to perform a total knee replacement.
4. How long does the procedure take?
A total knee replacement typically takes approximately 60-90 minutes to complete. The total time from when the patient is brought into the operating room, anesthesia is administered, the procedure is completed, and the patient transported back into the recovery room is approximately 2 hours.
5. What type of anesthesia is used during the procedure?
There is a combination of techniques used to administer anesthesia during a total knee replacement. Most patients have a spinal block performed by the anesthesiologist at the start of the procedure. This will temporarily block any sensation in the legs and provide excellent pain relief for the first 12-24 hours. This will also allow the anesthesiologist to not be required to use as much general anesthesia medicine during the procedure. The patient will still be “asleep” during the procedure, but typically does not require to be intubated. This should allow for less postoperative nausea and vomiting. In addition to this, a combination of numbing medicine, pain medicine, and an anti-inflammatory medicine are injected into the tissue around the knee at the end of the procedure to also help with postoperative pain control.
6. What should I expected during the hospital stay?
Most total knee replacements are performed on either Monday or Tuesday and the patient can be expected to stay 3 nights in the hospital. On the day of surgery, the operative leg will be placed in a continuous passive motion (CPM) machine that will begin gentle range of motion for 4-6 hours per day. Depending on how the patient feels, the patient may also get out of bed to a chair, but the amount of walking will be limited secondary to the spinal block. The patient may begin to eat after they are fully awake from the anesthesia and have no nausea or vomiting. A liquid or soft diet will be started and then advanced to a regular diet as tolerated.
On postoperative day 1 and 2, the CPM machine will be used for 4-6 hours a day and physical therapy will be initiated. This will include range of motion exercises, strengthening and stretching exercises, and walking with the assistance of a walker. Physical therapy will be twice a day.
The patient can expect to be discharged on postoperative day 3 after the morning physical therapy session.
7. Will I go home after surgery or go to rehab?
There are two options to consider after the inpatient hospital stay is completed. The first option is to arrange for home health and home physical therapy to come to the patient’s house 3-4 times a week for wound checks, administration of any medicines, dressing changes, and for physical therapy. This is an appropriate option if the patient has been ambulating well while in the hospital and has appropriate help at home.
The second option to consider is for the patient to be transferred to a rehabilitation facility. This would be similar to a skilled nursing facility, but with the ability to provide continued physical therapy twice a day. The typical length of stay is between 5-12 days, and then the patient is discharged to home.
8. What can I expect the post operative course will be like?
Week 0-2: The patient can expect to be ambulating with the assistance of a walker and have limited range of motion in the knee (0-90). The patient can expect to be using pain medicine on a regular basis during this time. The patient will be doing home physical therapy during this time. The patient will also be on a blood thinner for the first 2 weeks after surgery.
Weeks 2-6: Outpatient physical therapy will be started at this time and will continue for 2-3 times a week. A goal of achieving full range of motion should be completed by week 6. The patient can also discontinue the use of a walker and advance to a cane or and no assistive device as tolerated. The patient should continue to be working on range of motion exercises on a daily basis.
Weeks 6-12: If the patient has achieved a near full range of motion, the patient will begin to focus on more strengthening exercises at this point. Pain levels can be expected to be decreasing on a weekly basis and most patients can wean off pain medicine during this time. It is not uncommon for the patient to still feel weak and still have some achiness in the knee. The patient can then begin to increase their activities as tolerated, but would recommend no highly strenuous activities.
Weeks 12-16: Many patients feel like they are “over the hump” and are starting to resume many of their previous activities. There may still be some occasional swelling and achiness that can be expected. Occasional pain medicine may or may not be needed.
6 months: Patients can expect to be continuing to increase their activities and will feel like their strength is improving. Some weakness is still common with some occasional swelling. The patient should only require the occasional use of Tylenol or NSAIDs as needed. The patient can expect to continue to see improvements in their function, strength, and endurance of the knee up to one year from the operative date.
9. What are the risks of surgery?
Risks of surgery for a total knee replacement include bleeding, infection, damage to blood vessels, nerves, tendons, pain, stiffness, a decreased range of motion, fracture, implant failure, loosening of the implants, deep vein thrombosis, pulmonary embolus, any medical or cardiac complications, and the need for further surgery.
10. How long do Total Knee Replacements last?
There have been multiple studies demonstrating high success rates of over 90% at 12-15 years following a total knee replacement. Loosening of the components can then occur at this time which can cause pain and require a second surgery to revise the components.
11. Would I be a candidate for a partial knee replacement?
Some patients can be a candidate for a partial knee replacement if the arthritis is isolated to only one part of the knee, the remaining cartilage is in good condition, and there is no ligamentous instability of the knee. The advantage of a partial knee replacement is less surgical dissection, the preservation of normal cartilage, and a quicker recovery time.