The knee, the largest joint in the body, bears most of our weight. Due to the natural wear-and-tear that comes with constant lifting and moving, the knee is frequently affected by arthritis. Among the many forms of arthritis, osteoarthritis (OA) most commonly impacts the knee.
OA is a degenerative condition that involves the loss of the smooth cartilage surfaces on the end of bones. This can lead to bone-on-bone rubbing in the knee, which causes pain.
OA usually occurs with aging. For many years, knee replacement candidates were typically in their sixties or seventies, but increased sports participation at a younger age has contributed to rising numbers of knee problems earlier in life. As materials used in knee implants improve, knee replacement surgery is being used to treat OA in younger patients.
Common causes of OA and how to slow its onset
A major component of OA is natural wear-and-tear. Other factors also play a role in the development of OA, including:
- Genetics. If you have a family member with hip or knee arthritis, you have a higher risk.
- Anatomic variant. How a body part is formed in an individual can lead to increased cartilage deterioration.
- Excessive weight. Force on the knee plays a large role in the amount of stress on the knee and subsequent wear. For every pound you lose, that’s 4 to 7 pounds off the knee joint.
- Trauma. An injury can lead to post-traumatic arthritis, a form of osteoarthritis spurred specifically by injury.
Arthritic knees can come in pairs. However, it’s more common to develop OA in one knee, as people may favor one leg over the other while walking or running.
It’s important to keep the knees healthy. Measures can be taken to reduce the rate of OA, which normally develops slowly, as well as encourage successful treatment. These include treating knee injuries when they occur, maintaining healthy body weight, and keeping muscles strong around the knee.
“As people age, we tend to exercise less. However, exercise contributes to stronger and healthier knees,” says Antonia Chen, MD, an orthopaedic surgeon who performs hip and knee replacements in the Department of Orthopaedic Surgery at Brigham and Women’s Hospital (BWH).
Diagnosis of knee osteoarthritis
Diagnosis begins with a physical examination and x-rays. During the physical exam, the doctor looks for joint swelling, a range of motion, muscle strength, tenderness, and gait problems. The x-rays might show narrowing joint space, bone changes, or the formation of bone spurs – all signs of an arthritic knee. Other tests may be needed to determine the cause of your knee pain. These may include an MRI, CT scan, or bone scans.
Consider nonsurgical treatment options first
Knee OA is not life-threatening and pain thresholds vary, so you have time to decide when you want to pursue treatment. Still, if you have knee pain, it’s wise to seek advice in order to make an informed decision.
Many methods can effectively manage knee pain and should be tried before surgery. Multiple pain management strategies can be tried simultaneously; some combinations may be more effective at pain management than one method alone.
Dr. Chen talks about these options as “Round One”:
- Weight loss: Diet and exercise help with this.
- Activity Modification: Pain in an arthritic knee can be caused by some regular activities, including running. Switching to the elliptical machine, for instance, may result in less pain.
- Medications: Non-steroidal anti-inflammatory medications (NSAIDS) including ibuprofen, naproxen, and aspirin are available over the counter. Acetaminophen can also be used.
- Knee braces: Over-the-counter or custom braces help with pain in the knee.
According to Dr. Chen, “Round Two” of non-operative treatments includes cortisone injections. Relief from the injection usually lasts around three months, although it varies. Patients can receive repeat injections after the prior one wears off, but each injection may be less effective than the previous.
Complications may include increased blood sugar levels, joint infection, and slight cartilage damage, which can affect patients with mild arthritis. For this reason, injections are often reserved for individuals with moderate to advanced arthritis who have minimal cartilage that could be damaged.
Other injection options include viscosupplementation (gel shots), stem cell injections, and platelet-rich plasma. These are controversial, and the latter two aren’t usually covered by insurance.
Once you decide on surgery, preparation is important
If you have tried all the conservative treatment options and the pain is affecting your ability to function, it’s worth considering surgery. Because the surgery is elective, doctors and patients have time to work on minimizing risk and maximizing positive outcomes by addressing health habits and other conditions beforehand.
An optimal surgical candidate:
- Has a BMI < 40 (kg/m2).
- Does not currently smoke.
- Has not had a cortisone injection within the prior three months.
- If diabetic, has hemoglobin A1C levels under 7 percent.
In addition, research shows that pre-surgical strengthening may contribute to better post-operative outcomes. “Quadriceps strengthening is especially effective, so we focus on that,” says Dr. Chen.
One gauge of quadriceps strength is through a single-leg stance: being able to stand on one leg for at least 10 seconds is ideal. Try it – the longer, the better!
The type of surgery depends on the condition of your knee. For an advanced arthritic knee, total knee replacement is likely the best option. Otherwise, there are two more options:
- Partial Knee Replacement is a possibility if only one part of the knee shows damage. Because it is more conservative than a total replacement, recovery may be faster and the knee may feel more natural. However, you may need a conversion to a total knee replacement in the future.
- Arthroscopic Debridement, during which the meniscus is shaved down, is suitable for a patient with a torn meniscus and mechanical symptoms (such as locking).
Each of these surgeries usually takes approximately one hour, and the patient is walking that afternoon. Patients can be discharged home that day or stay one to two days in the hospital.
Patients will experience some pain immediately after surgery. Your doctor will help you manage the pain with injections during the surgery and oral medications in the weeks afterward. Patients may also have stiffness and swelling. Dr. Chen recommends that patients complete exercises, either on their own or with a physical therapist, and remember to elevate their knee above the level of the heart as much as possible.
Set reasonable expectations for recovery
People often expect the total knee replacement to be a total cure – which it is not. “It takes work, time, and effort to make the knee feel good again, and even then, it won’t be the same knee you had when you were 20 years old,” Dr. Chen reminds her patients.
Full recovery can take as much as a year, but the knee will feel better as you begin to heal from surgery.
Patients often ask when they can return to driving. That depends on which knee received the operation. For the right knee, individuals can usually drive after three-to-four weeks; for the left knee, you could drive as soon as two weeks. The important factor is the strength of the quadriceps, which affects your ability to move from brake to gas safely. “I tell patients to go to an empty parking lot to practice, and when they feel comfortable enough to hit the brake if they needed to, they’re ready to drive,” says Dr. Chen.
Another common question is when patients can return to work. Because it depends largely on the amount of physical labor in a person’s job, at-home recovery can range from two weeks to three months.
Dr. Chen reminds patients that recovery takes time: “The key is expectations. I always tell patients to remember their pain before surgery, because afterward it normally feels a lot better than that.”
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