Cartilage loss increases joint friction

Q: I am a 77-year-old woman diagnosed by my orthopedist with reduced cartilage in my right knee, probably due to wear and tear and arthritis. I'm not in pain, but I have developed bone spurs, and there is some swelling. What can I do to prevent further degeneration?

A: Cartilage is a remarkable tissue that, depending on its type and location, reduces friction, acts as a shock absorber, enhances strength, provides structure and augments flexibility.

There are three types of cartilage in the body. Elastic cartilage, which is found in the outer ears and the larynx, provides shape and elasticity. Fibrocartilage, tough and strong, is found in joint capsules, ligaments and the invertebral discs of the spine. When it comes to the joints, we're talking hyaline cartilage. Smooth to the touch and a pale bluish-white in color, it is the most abundant type of cartilage in the body.

Hyaline cartilage caps the ends of the bones and lines the inner surfaces of joint capsules. It is due to its smooth surface, with an assist from specialized fluids, that bones can meet and glide, almost frictionless, against one another. The key word here is "almost." Over time, wear and tear do take a toll.

Cartilage can also sustain physical injury. Twisting a joint can result in damage. So can the force and impact common in sports. Ongoing inflammation from autoimmune conditions can also result in damage. And because cartilage lacks an active blood supply, it is slow to heal.

When cartilage wears away, the bone spurs you have developed often occur. These bony lumps, which form on the surface of joints, are an adaptive response as the body strives to maintain stability in the knee joint. Bone spurs themselves don't hurt. However, they can limit range of motion and may press or rub against neighboring structures or tissues, which can be painful.

To slow cartilage loss, you want to reduce stress on the joint. That means limiting repetitive and high-impact activities. These require the knee to be a shock-absorber, which can further damage the connective tissues of the joint. The correct shoes are also important. Avoid high heels, which greatly increase stress on the knee. Instead, opt for shoes that are soft and flexible, with either a flat or low heel. It's also important to reach and maintain a healthy weight. Studies have shown that being overweight, which stresses the joints, can contribute to cartilage loss.

You also want to manage inflammation. Your doctor may recommend nonsteroidal anti-inflammatory drugs, or NSAIDs, such as ibuprofen or naproxen. These can lessen the swelling that you have experienced. NSAIDs can also be helpful for people with cartilage loss who are in pain. When swelling is pronounced, injections may be recommended. Steroids can address inflammation and swelling. Hyaluronic acid, a substance that occurs naturally in joint fluids, can aid in lubrication. Platelet-rich plasma, which is derived from a patient's own blood, can also stimulate healing. Your doctor can advise you if any of these may be helpful for your specific situation.

Q: I was surprised to find out a co-worker gave his nephew a kidney several years ago. He never mentions it and I don't want to invade his privacy, but I would like to know more about the process. What does it take for someone to donate a kidney? Is it safe for them to do it?

A: Your co-worker is what is known as a living donor. It's just as it sounds - the donation of an organ by someone who is still alive.

The kidney is the most frequently transplanted organ from a living donor. While less common, it is also possible to donate a lobe of the liver, all or part of a lung, a portion of the pancreas or part of the intestines.

The majority of the 6,000 organs provided by living donors each year come from relatives, loved ones or close friends. A small number come from a donor who has chosen to help someone they don't know but who is in great need. Whatever the circumstances, becoming a living donor is a weighty decision that requires serious thought.

Depending on the transplant center, the prospective donor must be at least 18 or 21 years old. They must also be mentally competent to make the decision to donate and be in good health. Conditions that can interfere with becoming a living organ donor include diabetes, cancer, uncontrolled high blood pressure, hepatitis, HIV or an active infection. All of this is ascertained during the evaluation that is required of all potential donors. This begins with blood tests and tissue typing to see if a potential donor is a good match. If so, the person undergoes additional testing, including heart and lung exams, a colonoscopy, and liver and kidney function tests.

Not surprisingly, given the enormity of such a decision, a mental health assessment is an important part of the screening process. The transplant center also makes sure the donor has the financial, medical and personal support required when someone undergoes major surgery.

The transplant itself is done under general anesthesia and takes three to four hours. Most kidney transplants are now done laparoscopically, which means small incisions and a faster recovery time. The timing of a return to work and a regular routine varies, but typically takes three to six weeks.

Short-term risks to the donor include those involved in any surgery. These include infection, pain, blood clots and an adverse reaction to anesthesia. Long-term risks include the natural decline in kidney function that accompanies aging and developing a disease that itself impedes kidney function. This includes Type 2 diabetes, high blood pressure and obesity. A donor loses 25% to 35% of their kidney function. To compensate, the remaining kidney increases in size.

The data show that donating a kidney does not affect the donor's life expectancy. People on the kidney transplant list wait an average of three to five years for an organ. Tragically, some don't survive the wait. In donating a kidney to his nephew, your co-worker has made a courageous and generous choice.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.