Patients with knee arthritis usually come see a physician after years of slowly increasing pain. The hallmark of knee arthritis is pain with weight bearing activity. Standing, walking, and getting up from a seated position are usually the first and most severe complaints. Later in the process, there can be pain at rest and even pain at night. An exception to this general rule is patients with arthritis only under the kneecap (patellofemoral arthritis). These patients may have pain only with getting up from sitting and stair climbing, but not walking or standing on level ground.
Pain can be pinpoint to only one part of the knee. This can be the inside (medial), the outside (lateral), the front (anterior), or the back (posterior). Other patients may have pain all over the knee. It is common for pain to go down into the shin, but usually does not go down into the foot or ankle. It is also not common for the pain to go up into the thigh.
Knee osteoarthritis is the wearing away of the cartilage that normally surfaces the bone. Cartilage does not have nerve endings, but bone does. That is why it hurts to put weight on an arthritic knee. The more severe the cartilage wear the more severe the pain. This usually happens slowly and is why pain increases slowly over a long period of time.
Osteoarthritis is diagnosed by a history, physical exam, and x-rays. The history of your pain is important. Your doctor will want to know about any history of major trauma or previous knee surgeries. If your symptoms are unusual for knee arthritis as described above, you may have a different cause for your pain. During the physical exam, your doctor will check to see if you limp when you walk. We are also looking for any deformity in the leg, because it is common (but not necessary) to be bow legged or knock-kneed with knee arthritis. Also important is any limitation in the motion of the knee or instability (looseness) with the ligaments. Any defects in your blood flow (pulses) or feeling in the skin (sensation) of the painful leg will be noted along with your general muscle strength.
The most important test for osteoarthritis is a standing x-ray of your knee. In our clinic, we x-ray your knee straight and slightly bent while standing. We also x-ray your knee from the side and under the kneecap (patella). On your first visit, we will x-ray your pelvis to assess your hips, because hip abnormalities can cause knee pain. The cartilage that normally coats the ends of your bones at the knee does not show up on an x-ray. So if you are missing cartilage, there will be less space between the bones of the knee when you stand and we will see this on x-ray. The space may be slightly narrowed (mild arthritis) or completely gone so that the bones are touching (severe arthritis).
Unfortunately, at the present time, there is no cure for arthritis. The missing cartilage cannot be replaced with similar cartilage by medicine, injection, or surgery. Therefore, treatment is directed toward the symptom…PAIN. There are several treatment options directed at the two causes of the pain. The first cause is inflammation. As the cartilage wears away, the knee becomes inflamed as a healing response. One of the results of inflammation is pain. Non-Steroidal Anti-inflammatory Medications (NSAIDS or arthritis medication) can help this. In milder cases, over the counter medications can be effective. Examples include Motrin, Advil, Ibuprofen, and Aleve. In moderate to severe arthritis, a prescription anti-inflammatory or anti-inflammatory injection like Cortisone (steroid) may be recommended. Glucosamine, Chondroitin sulfate, and other supplements may help your pain, but how they work is unknown and most studies do not show a predictable decrease in pain for patients with knee arthritis. The second cause is mechanical. The more times the bones push together and the more force they are pushed together with, the more pain you will have. Activity modification (“if it hurts, don’t do it”) is the main treatment for this. Certainly high impact exercises should be substituted for low impact aerobic exercises like biking, elliptical trainer, or even swimming or pool exercises. Using a cane, crutch, walker, or other assistive device can also decrease the pain when walking. A cane or crutch should be use on the opposite side of the painful knee. Braces that “unload” the painful side of the knee may also be helpful for walking pain especially in patients that are bow legged. Overweight patients will benefit from weight loss because of the reduced force across the knee joint.
For patients with long standing severe knee pain that has not gotten better with the treatments discussed above AND x-rays that show complete loss of space (bone on bone) surgery may be indicated. The only surgery that has shown predictable and durable pain relief for bone on bone knee arthritis is knee replacement. Ultimately, a patient’s decision to have a knee replacement is a risk-benefit decision for that individual. Knee replacement is an elective procedure. Patients’ functional limitations and pain should affect their quality of life enough to warrant a major operative procedure. Non-operative treatments should be exhausted. Medical risks should be minimized and fully understood. Lastly, x-rays should be severe enough to explain the pain and warrant a surgical procedure.
About 85-90% of knee replacement patient are fully satisfied with their results. Dissatisfaction can be caused by surgical or medical complications, which we will discuss. Dissatisfaction is also more common in patients with mild symptoms, or mild x-rays. One of the most common causes of dissatisfaction is unmet expectations related to postoperative pain, recovery time, or ultimate functional recovery and activity level. So…
What can one expect after knee replacement surgery? It takes 12-18 months to fully recover from a knee replacement. What does that mean? It means that you may improve in function and continue to have less surgical pain for a year and a half. Fortunately, it does not take that long to be functional and satisfied, so let us walk through a typical recovery from the beginning. Surgery takes about one and a half hours. Anesthesia choices include spinal or general (going to sleep). Sometimes a nerve block of the leg will be done before surgery starts or the tissue around your knee will be injected in surgery to help with your pain right after surgery. Based on your medical history and your preference, you and the anesthesiologist will decide which is best at your preoperative appointment one to two weeks before surgery. Many knee replacements can be done in the outpatient setting. If you have major medical issues you may be asked to stay overnight. To be discharged home you must be medically stable, comfortable on pain medication pills, and independently mobile. This means you can get out of bed and walk on your walker with minimal assistance, bend your knee, dress yourself, go up and down some stairs, and get in and out of a car. Therapy usually starts on the day of surgery and continues twice daily if you need to stay in the hospital.
After discharge from the hospital, physical therapy is your job for several weeks. Most patients go home and start outpatient physical therapy the day after. You cannot drive until you are off your walking aids and not requiring pain medication during the day, so you need a driver for a few weeks (typically 2-4 weeks) to go to therapy 2- 3 times a week. Therapy usually goes for 6 weeks. If you have several medical problems or can find no assistance at home then you may qualify for and inpatient rehab or skilled nursing facility until you can be at home. In rare circumstances, home health physical therapy may be a patient’s only option.
Pain varies among patients after surgery, but most patients are pretty miserable for 2-4 weeks. You have gone from pain that hurts when you walk and feels better when you rest to pain that is there all the time whether you walk or rest. Pain medication is often needed to be comfortable enough to participate in physical therapy, but other medications help with pain. Non-opioid pain relievers that will be recommended include Tylenol, Mobic (Meloxicam) or Celebrex, and Tramadol. Many patients take narcotic (opioid) medications 2-3 times daily for the first 1-2 weeks and then decrease the dose or frequency for another 1-2 weeks before stopping. By 4 weeks you should be able to tell the “old” pain is gone and the “new” surgical pain is getting better and there is hope. You should be taking much less pain medication at this point or be off all together. You will be off your walker and probably your cane at this point. When I see patients 6 weeks after surgery, they are usually walking well with minimal or no limp. They can straighten and bend their knee fully to 120 degrees or so (if they could bend at least that far before surgery). They still have swelling, and they still have pain in their knee. This pain is not severe, but most patients say it is always there. This pain is usually worse with sitting for a long time or with a lot of walking or standing. Difficulty sleeping through the night because of discomfort is common at this point. Easy fatigue is also still present for most patients. From 6 weeks to 3 months much of this pain slowly goes away. At 4-6 weeks you will begin low impact aerobic exercise and increase the time spent doing this each week. Walking, elliptical trainer, biking, and pool exercises are examples of what is encouraged. By 3-4 months most patients are more functional and have less pain than they did before surgery. Periods of time will go by in the day when you “forget” about your knee. At this point there is still some swelling that comes and goes based on activity and some occasional pain that is related to activity. At this point you are about 80 percent recovered. The next 20 percent takes another 8-14 months. You improve because the inflammation caused by surgery continues to go away. This process is slow and cannot be sped up. Each patient is a little different. The other big reason for continued improvement is strength. Although formal physical therapy only lasts 6-8 weeks, exercise and continued therapy on your own should continue for at least a year and a half and preferably forever.
“When can I return to work” is a common question. We will discuss this individually, but here is a guide. If you work from home you can start whenever you are not taking narcotic pain pills throughout the day. Usually 1-2 weeks. If you work in an office in a mostly sitting job, return is 4-6 weeks. If you walk or stand much of the day you may need 6-8 weeks before returning. Patients with jobs that are more strenuous may need to be out as long as 12 weeks before returning without restrictions.
As you can see, recovery is lengthy, but if your pain is severe enough and affects your daily function and quality of life then the ultimate pain relief may be worth it. Most patients are very satisfied, but complications can occur and you should be aware of the more common ones. In no particular order, they are infection, blood clots, stiffness (not getting full range of motion), early loosening of the parts, fracture or breaking of the bone, and nerve injury.
Anytime a cut is made on the skin it can become infected. This is also true in knee replacement. This complication happens in less than 0.5 percent of patients, but can be devastating. Most infections require more surgery for a cure. In more than half of cases, the knee replacement must be removed and a temporary antibiotic loaded “spacer” placed in the knee. The spacer and 6 weeks of IV antibiotics usually cures the infection. Then another surgery is required to again place knee replacement components. To help avoid infection all patients receive antibiotics just before surgery. We operate in fully sterile hooded suits in special operating rooms that move air in and out more frequently. All patients are screened before surgery to see if they carry any kind of Staph bacteria and are treated accordingly before surgery. Patient factors that increase the risk of infection and must be optimized before surgery include diabetes, smoking, malnutrition and obesity. Infection is less common after the initial postoperative period, but can happen any time bacteria enters your bloodstream.
Blood clots are very common in knee replacement if nothing is done to prevent them. Most clots in the lower leg have no symptoms and the body dissolves them without the patient every knowing. Larger clots in the upper leg can cause prolonged swelling and vein damage and can travel to the lung (pulmonary embolus). For this reason we want to prevent blood clots. I will use mechanical and chemical (medication) prevention. In the hospital, walking as soon as possible is important. You will also be encouraged to pump your ankles hourly and will wear pumps when in bed (devices that squeeze your feet or lower leg periodically). Most patients will also take aspirin for 6 weeks. If you are high risk for blood clots you may need to take a stronger blood thinner pill like Coumadin (warfarin) or Xarelto for 4-6 weeks followed by aspirin. The highest risk patients include those with a previous blood clot, a strong family history of blood clots, cancer in the last 5 years, smokers, and those that are overweight.
Stiffness can also affect the outcome of a knee replacement. The most common predictor of range of motion (bending) after a knee replacement is range of motion before a knee replacement. This means that stiffer patients stay stiffer compared to more flexible patients. We still want you to get at least 115 degrees of flexion by 6 weeks. Not everyone achieves his or her range of motion goals by 6 weeks. If you have less than 90 degrees at this point then I may recommend a manipulation under anesthesia. This is when we put you to sleep and bend your knee to break up any scar tissue that has formed and is blocking your progress.
For a knee replacement to function well and provide pain relief, the implants must be well attached to the bone. In most cases, this fixation is achieved with bone cement. Bone cement is not an adhesive. It is more like a grout similar to that used in floor tiles. The early and long term fixation of the parts relies on this material. If it cracks it will loosen just like a tile in the floor. Most implants remain fixed to the bone for more than 15-20 years; however, early loosening (less than 5 years) can occur in a small percentage of patients (around 2 percent). Obesity and infection are the most common reasons for this.
Bone fracture is very uncommon with knee replacement surgery. If a fracture of the bone occurs during surgery or is detected with x-rays after surgery you may be asked to protect the bone with less weight bearing and a longer time on the walker. Major nerve injury is also very rare, but injury to skin sensation is almost 100% to the outside of the skin incision. That means this skin will feel dull or completely numb after surgery. This decreases over the 1st year, but at 1 year after surgery as many as 7% of patients still notice numbness on the skin outside of the incision that may bother them.
Medical complications include but are not limited to heart problems (heart attack, arrhythmia, and heart failure), low oxygen (higher in patients with sleep apnea), constipation, and kidney problems. These complications are not common but can happen more often in patients with these problems to begin with.
It is also important to understand how long a knee replacement may last. Think of a knee replacement as a brand new tire. It lasts for a long time, but will eventually wear out. If it is put in well and balanced correctly it will last longer. How it is used also affects the rate of wear. Repetitive impact activities like running or jogging for exercise, competitive ball sports, or repetitive jumping exercises may be possible with a knee replacement, but will likely shorten the lifespan and are not recommended. Lower impact aerobic exercise like walking, elliptical trainer, biking, hiking, swimming, golf, and doubles tennis are encouraged. Maintaining a healthy weight is also key to preventing premature loosening of the knee replacements connection to the bone. If you treat the knee replacement right it can easily last 15-20 years without any further surgery.
It is no surprise that a knee replacement is not a normal knee. Occasionally, a patient will say that it feels like their knee before arthritis started as if they have forgotten about it, but this is the exception. More often, even a very satisfied patient, will notice things about their replaced knee that are not normal or even bothersome. I may make a clicking sound with walking, stair climbing, or getting out of a chair. Usually this is only noticed by the patient, but can sometimes be loud enough to be heard by others. This is because the metal and plastics parts are harder than the original parts. Other common comments are that kneeling is uncomfortable even years after the surgery and that the knee feels ‘tight” with sitting for a long time.
In the right patient, knee replacement is one of the most successful surgical procedures. Even though it won’t be normal or just like your knee before, if you have pain in your knee much of the day with normal activities your knee will be better after you have fully recovered from a well done knee replacement.
If you are interested in talking with Dr. Morrison in more detail about your knee arthritis call to schedule an appointment at his Nashville or Brentwood office at 615-342-0038.
