William B Kurtz | Total Knee Replacement

Introduction

Total knee replacement is one of the most successful operations that orthopedic surgeons perform. A total knee replacement is an elective surgery, which means patients elect to have a joint replacement done. As a physician, I never tell patients they have to have their knee replaced. Although the surgery is elective, it is covered by most insurance companies; however, depending on your policy you maybe required to make a small co-payment. My philosophy is to give my patients as much information as possible for them to make informed decisions regarding their health and knee pain and let them tell me how and when I can best help them.

The purpose of this web page is to educate patients about the major aspects of knee replacement surgery. Many studies have shown that an informed patient will have less surprises and be more satisfied with their surgery. I do not intend to scare people away from getting their knee pain treated. Although the following information is a reasonable overview of what I consider the major aspects of knee surgery, it is not a substitute for a clinical consultation where I can directly answer your questions. If you would like more information, please schedule an appointment to see me.

History of Total Knee Replacement

Total knee replacements were developed in the 1960s and 1970's, and have gone through many changes in techniques, implants, and post-operative care over the years. A wide variety of methods and implants are used today, and good results can be achieved with most methods. The most important determinates of the patient’s outcome are the patient, the surgeon, and the hospital staff. Other factors which might have a smaller impact include the patient’s pre-operative education and expectations, the type of components implanted, the surgical approach, the post-operative rehabilitation, and the length of the incision. Multiple studies have proven that outcomes improve with increased volume by the surgeon and hospital, so I feel that patients have the best outcomes with joint replacement surgery from surgeons that specialize in joint replacements.

A knee replacement involves replacing the end of the thigh bone (femur) and the top of the shin bone (tibia) with metal parts that then act as a new knee joint. A plastic (polyethylene) insert is positioned between the 2 metal components to help cushion the new knee joint and allow the knee to bend. The undersurface of the knee cap (patella) is replaced by a plastic button as well. The parts are fixed into your bones with bone cement. The parts are made of cobalt chrome, titanium, and/or polyethylene. Complex revision replacement surgery may involve bone graft often from a cadaver. For a first time surgery, it is likely that your incision will be 12 cm of about 4 inches in length.

Surgical Approach

Total knee replacements are preformed through an incision on the front of the knee. There are some different ways to handle the soft tissue and extensor mechanism which are discussed below. Each approach has advantages and disadvantages.

Medial Parapatellar Approach

A medial parapatellar incision involves cutting the quadriceps tendon above the knee cap (patella) and around the inside (medial) of the knee cap. The tendon is then repaired at the end of the procedure. The idea behind cutting the tendon is that the tendon might heal better than cutting into the muscle belly of the VMO. The patella is typically flipped during this approach to gain access to the knee joint which may or may not affect the knee rehab in the short term.

Mid-Vastus Approach

A mid-vastus approach does not cut the quadriceps tendon but instead cuts into the VMO muscle belly and around the inside of the knee cap. The idea behind leaving a large portion of the VMO attached to the quadriceps is that the VMO muscle may help patellar tracking and knee extension strength. The muscle belly is repaired at the end of the procedure. The patella may or may not be flipped during this approach.

Sub-Vastus Approach

The sub-vastus approach elevates the VMO muscle instead of cutting into it. The incision then extends around the inside of the knee cap. The patella is typically not flipped with this approach. This approach is difficult in muscular patients with large VMO muscles. Theoretically, the patella tracking and quadriceps muscle strength is optimized with this approach.

Quad-Sparing Approach

The quad-sparing approach cuts just the inside of the knee cap. This approach requires special side cutting instruments. There is definitely a steep learning curve regarding the use of these instruments and many physicians (including myself) worry about the accuracy of the bone cuts and limb alignment with these side cutting instruments.

Lateral parapatellar Approach

The lateral parapatellar approach is a relatively uncommon approach where the incision extends around the outside (lateral) of the knee cap. Some surgeons will use this approach for severe valgus deformities.

Good results after a total knee replacement can be achieved with any of the above approaches. Patients should allow the surgeon to perform the approach the surgeon is most comfortable with.

Cruciate Retaining vs. Posterior Stabilized

The debate of cruciate retaining (CR) versus posterior stabilized (PS) knee replacement has been ongoing for >15 years and will not likely be solved any time in the near future. A full discussion of this topic is not possible in the section, but I will attempt a quick over view.

Cruciate Retaining

A cruciate retaining knee implant leaves an intact posterior cruciate ligament (PCL) in the back of the knee to help with knee flexion and ligament tension. The advocates of the CR knee design claim less bone removal from the femur, easier femoral component revision, and tighter ligaments in the back of the knee. The opposition of this approach claim that the PCL is diseased, the PCL does not help with knee flexion in a total knee replacement (no femoral roll back), the PCL might rupture and lead to late instability, and that ligament balancing is harder and less predictable with a cruciate retaining knee implant.

Posterior Stabilized

A posterior stabilized knee implant replaces the PCL with a cam and post design of the knee replacement that ensures femoral rollback. The advocates of the PS knee design claim more predictable knee ligament balancing and more predictable flexion. The opposition of PS knee designs claim the cam and post design causes additional polyethylene wear, the patella may "clunk" because of the design, and that considerable amounts of femoral bone is lost during a knee revision of a PS design.

Computer Navigation / Computer Assisted Surgery

Computer navigation is a technique where the surgeon inputs data into a computer tracking system and then uses that computer to help position the components appropriately. Knee replacement surgery can be successful with and without surgical navigation, but many papers have shown that the overall limb alignment (how straight your leg is) is accurate more often when surgical navigation is used. Knee alignment does have a direct affect on the longevity of the knee replacement. Without surgical navigation, the surgeon inserts a long rod up the inside of the femur (and sometimes tibia) bone. With surgical navigation, the surgeon does not have to insert a rod up the femur. It is likely that by not violating the femoral bone, patients who have a surgical navigated knee replacement will have less pain after the surgery. I currently use the Stryker navigation system and have been pleased with the results.

Mobile Bearing/Rotating Platform Knee Replacements

Some orthopedic companies (Depuy) offer knee replacements that allow the components to move inside the knee. The plastic insert can rotate on a post and therefore the knee rotation is determined by the muscular forces around the knee. The advantages of this device are that the knee assumes the rotation that best fits that particular patient's need and is not limited by the rotation that the surgeon selects in the operating room. By allowing the liner to rotation, the stress on the plastic is likely decreased which might help the plastic last longer. Some studies have suggested that the liner does not continue to rotate after it has been in the knee for a long time, but this may or may not matter. Whether this rotating technology will improve the long term survival of the knee replacement remains unknown, but the short term and intermediate term results have been good. If you are interested in this type of knee replacement, please inquire about whether you would be a good candidate for the rotating platform knee during your office visit with Dr. Kurtz.

Gender Specific Knee Replacements

Zimmer, a large orthopedic company, offers knee replacements that are specifically designed for women. The femoral component of most knee replacement are available in small, narrow sizes designed for smaller knees (presumably women's knees) and larger, wider sizes designed for larger knee (presumably men's knee) There are typically about 6-8 total sizes of femoral components. The gender specific femoral components are available in the small and large sizes, but also come specifically in a narrow (female) and wide (male) size.(7 narrow sizes + 7 wide sizes = 14 total sizes) For instance, a surgeon could select either a size 3 narrow or a size 3 wide femoral component with the gender specific system. A surgeon using a different system would only be able to select a size 3 component that would come in only one width. The tibial components in all system are not gender specific. The rationale behind this design is women can have a more narrow knee than men, and Zimmer feels that previous knee designs have not made the small components designed for women narrow enough. It remains to be seen if a gender specific knee system will improve knee replacement results or just be a brilliant marketing move. I personally think my patients do well with the Gender Specific knee, but I attribute these outcomes more to the favorable design of the Zimmer NexGen knee system than to the availability of gender specific sizes.

Pre-operative Joint Replacement Education Class

Multiple studies have shown that pre-operative education improves patient’s outcomes after joint replacement surgery.
Baptist Hospital offers a free 3 hour pre-operative instructional class.
Although it is not imperative, I strongly recommend that my patients attend this class.
During this class,
- you will meet with the nurses that will be taking care of you after your surgery
- discuss what you can expect after surgery
- talk about what you need to bring with you to the hospital
- discuss whether you plan to go home with a home health nurse visiting you in your house or to an inpatient rehabilitation center
The pre-operative joint class is offered Tuesday, Wednesday, and Thursday mornings
After the pre-operative joint class, you will meet an anesthetist to discuss with him/her your anesthetic options. Ask which medications you should take the morning of your surgery

Medical Clearance

If you have not seen your medical doctor recently, you should make an appointment with him/her as soon as possible. Your surgery can then be performed once your medical doctor clears you for it.
If you have recently seen your medical doctor, you should have him/her send a note to my office stating that you are medically fit for your surgery.
If there is a question as to whether you have seen your medical doctor recently enough, call your medical doctor and ask him or her.
If you see a medical specialist (e.g., a heart or lung doctor), have him/her also send a note to my office stating that you are medically fit for your surgery.
If you have no medical doctor and no medical problems, let me know during your clinic visit.
If you have no medical doctor and you do have medical problems, I will refer you to a medical doctor prior to any surgery.
You must inform my office immediately about any infection anywhere on your body, especially in the skin over your operative site. This can include a pimple or scratch, or infection in your fingernails, toenails, teeth, or urine.
If you have any ongoing dental problems or even old infections, you must see your dentist before the operation, and have him/her contact my office.

Blood Donation

Patients are welcome to donate their own blood at the Nashville American Red Cross prior to surgery with the intention of receiving their own blood after surgery should the need arise.
If you donate your own blood before surgery, please remind me prior to the operation, so I can be certain that you receive your own blood.
As the likelihood of needing a blood transfusion is relatively low, I neither encourage or discourage pre-operative blood donation.
Patients with anemia and relatively low pre-operative blood levels (hematocrit) are more likely to need a post-operative transfusion, and probably should consider donating blood.
Patients with serious medical problems are also more likely need a blood transfusion as well.

Unfortunately, if you donated your own blood, but we do not transfuse it back, that blood will not be given to anyone else and will be thrown out.

Medicines

You should stop all aspirin seven days before the surgery
Stop all “non-steroidal” anti-inflammatory drugs (such as Advil, Motrin, Alleve, Naprosyn, Celebrex etc.) three days prior to the operation.
If you take coumadin or other blood thinners (such as Plavix), please contact your medical doctor to find when it is safe to discontinue these drugs. If your medical doctor feels it is unsafe to stop these drugs, you must inform my office of this, preferably a week before your surgery.
If you are unsure whether any drugs you take fall in these categories, contact my office or your medical doctor.
All other medications should be continued unless your medical doctor instructs you otherwise. You should ensure that you bring a list of all your medications and their doses to the hospital with you for the pre-operative joint class and anesthesia visit.

Day of Surgery

Patients are asked not to eat anything for 8 hours before their surgery which typically means nothing after midnight..
Most of your normal medicines should be taken the morning of your surgery with a small sip of water. Please ask the anesthesiologist at your pre-operative visit which medicines you should take.
Patients report to the admission office on the first floor and will be taken up to the 5^th floor pre-admission floor.
Patients will see me, Dr. Kurtz, in the holding room prior to the operation.
Family members can wait in the family waiting room on the 4^th floor.
After the surgery, Dr. Kurtz will update your family members about how the operation went and how you are doing.
The patient will typically spend ~ 2 hours in the recovery room before being taken to their hospital room on the 8th floor.
Once the patient has been assigned a room, family member can wait in the patient’s room for the patient to arrive.

Wound Closure

I feel strongly that the wound closure is as important as the insertion of the components.
I therefore close the surgical incision with both interrupted and running suture in order to help evenly distribute the force on the skin edges.
All of the sutures dissolve over the following 6 weeks.
I also apply Dermabond (similar to Super Glue) to the incision after it is closed.
The incisions typically do not bleed or drain after surgery.
The water-proof dressing that is applied in the operating room typically does not need to be changed, and most patients remove the dressing about a week after the operation.

During your hospital stay

Pain medicine is custom tailored to every patient's needs.
Most patients received both a long acting oral pain medicine and additional short acting oral pain medicine as needed.
Patients will receive IV antibiotics for 24 hours after surgery.
Patients will receive a blood thinner for about 3 weeks.
Patients are encouraged to walk immediately after surgery.
Patients are encouraged to shower the day after surgery.
Physical therapists will work with each patient multiple times each day helping them learn how to safely walk and work on range of motion.
All IVs and catheters are removed once the patient is medically stabilized, usually 1-2 days after surgery.
I typically sees every patient at least once a day and often times twice a day. I also try to round on my patients over the weekend, but occasionally, weekend rounds maybe covered by one of my associates.
The hospital stay is usually about 2-3 days.

Leaving the hospital

A social worker will help determine how much help you need at home, and contact your insurance company to see what help is covered.
The physical therapist, social worker, and Dr. Kurtz will help determine whether you might be able to go home, to a rehabilitation facility, or a short-term nursing home.
Patients will receive prescriptions for pain medications and a blood thinner.
If the patient is taking the blood thinner, coumadin, your blood will be drawn at home or at a lab every 3 to 4 days for the next 3 weeks. You must also make sure that Dr. Kurtz’s assistant receives the results of your blood tests, and changes the dose of coumadin as needed.

Follow up

Patients first follow up is between 2 and 4 weeks after surgery

Patients second follow up is ~6 weeks after the first visit.

Patients are then followed on a yearly basis for a 2-3 years.

Every joint replacement patient should have an x-ray of their replacement every 2-3 years regardless if they are having pain or not.

Knee replacements usually fail because the plastic bearing surface wears out, the components loosen, or the components get infected. Pain is often not present until significant destruction has taken place. Revision surgery can be made more difficult by waiting until after this destruction has occurred. Appropriate follow up can hopefully identify small problems before them become bigger problems. If your knee replacement develops a new pain, notify my office immediately.

Risks of a total knee replacement

Blood Clots: Blood clots in your leg veins are possible after any surgery on the lower extremities. The occurrence of blood clots can be minimized with blood thinners, foot pumps, compression stockings, and early mobilization. The main danger of blood clots is if they dislodge and travel to your veins in your lungs. This phenomenon is called a pulmonary embolus and can result in respiratory difficulty, chest pain, or even death. Blood clots may or may not hurt or cause swelling in your leg and can occur anywhere in either leg. If you have unexplained pain or swelling in your legs, let Dr. Kurtz know as he may order a duplex ultrasound to look for a blood clot. If you feel chest pain or breathing difficulties, you should call 911 and then call Dr. Kurtz. The risk of these clots causing death has been drastically reduced, and is less than 0.1%. The treatment for a proven blood clot is additional blood thinners, and occasionally a filter in your veins.
Infection: Antibiotics are given before and after surgery to decrease the risk of infection, but an infection still can occur immediately or even years after the surgery. It is usually treated with another surgery to remove infected tissue and often the prosthesis as well. If the components are removed, a revision knee prosthesis can sometimes be inserted months later if the infection clears, but sometimes the patient is left without a knee joint or a knee fusion. Although patients rarely have life threatening problems from their joint infection, an infection is a devastating complication.

Stiffness: Patients may experience stiffness in the knee joint after surgery. Usually, a stiff knee before surgery is more likely to remain stiff after surgery; however, any knee can lose motion after surgery. It is imperative that patients work hard with the physical therapist after surgery to prevent the knee from getting stiff. Occasionally, the patient must have their knee manipulated under anesthesia to regain the motion lost in the post-operative period.

Component Loosening: Occasional the implanted components will loosen from the bone and change position. Component loosening can occur years after the surgery from wear debris from the plastic liner. The motion of the loose component may cause pain and require another surgery to revise the components.
Component Wearing out: A knee replacement is compromised of a metal femoral component, a metal tibial component, and a plastic insert. The plastic insert can wear out over time, usually 15-20 years. Just like the tires on a car, the more miles a patient puts on their total knee replacement, the sooner the plastic insert might wear out. The plastic insert can be replaced, if necessary.

Nerve Injury: Although extremely rare, nerves to your leg and feet can be injured during surgery. These nerves may or may not recover by themselves. If they do not, you may need a brace for your ankle, and your walking ability could be limited.

Ligament Injury: Although extremely rare, ligaments or tendons surrounding the knee can be injured during surgery. A ligament injury can usually be repaired during the surgery, but it may change the post-operative course. The ligaments most commonly injured are the patella tendon or the medial collateral ligament. A brace may be required to help protect the ligament as it heals after an injury.

Bleeding: Blood vessels around the knee are rarely damaged by the surgery. If excessive bleeding occurs during or after surgery, the patient may require a blood transfuse and might possible have to return to the operating room to correct the problem. Occasionally, blood gathers in the knee even if no major blood vessel is damaged, and this hematoma might require further surgery.

Limp: The limp that most people have before the surgery usually persists until the muscles become stronger after surgery. It sometimes never goes away, and sometimes the surgery creates a new limp. Most people's gait (walk) is greatly improved by joint replacement surgery.

Fracture: The femur, patella, or tibia can crack when preparing the bone for insertion of the components, actually inserting the components, or even years after the surgery. Fractures are usually treated with screws and plates, and usually heal. Occasionally, the knee components loosen when a fracture occurs and then the components have to be revised.

Osteolysis: Polyethylene bearings can wear over many years and cause osteolysis which is the body's response to the plastic wear debris from the knee replacement. The body tends to attack the tiny plastic particles and inadvertently causes the bone around the knee joint to weaken. The weakened bone can lead to fractures or component loosening.
Dislocation: The femoral component rarely can dislocate from the tibia component. Knee replacements with a rotating platform (mobile bearing) can also dislocate if the bearing surface rotates more than it should. If your total knee dislocates, your leg would be manipulated under anesthesia or sedation to place the components back together. Occasionally, unstable knee replacements need to be revised to correct this condition if it keeps occurring.
Need for Further Surgery: Though uncommon, knee replacements occasionally fail sooner than expected. Some other problems can also make further surgery necessary, including abnormal bone formation and irritation of the soft tissues.
Death: Though very rarely, patients have died following knee replacements. This is typically due to underlying medical or heart problems that arise or worsen from the stress placed on the body after the surgery.
Other Problems: This list covers only the most frequent problems encountered during knee replacement surgery. Just as every patient is unique, so are many problems and complications.
It is important to remind patients that although many complications have been reported in the orthopedic literature, most are minor and rare. Total knee replacement remains one of the most successful operations that orthopedic surgeons perform. I would not recommend it to you if the typical results were not outstanding.

Measures that you can take to help prevent complications include:

Call your primary care physician and/or my office immediately of any infections arise anywhere on your body after a joint replacement surgery.
Patients should receive antibiotics before any dental, urinary, or rectal procedure for two years after surgery. You might require pre-procedure antibiotics for a longer period if you have a disease that compromises your immune system. (Call my office if there are any questions.)
Always mention to any doctor performing an invasive procedure on you that you have a joint replacement.

Revision Knee Surgery

Replacing a previously inserted prosthesis is more difficult and less predictable than the first surgery. Each case has its own unique problems and risks. In all cases, the risks are much greater than the risks with first-time surgery. The recovery is often longer, and the results are less certain. The outcomes following revision surgery have greatly improved over the years.