"Lubrication" Injections for the Knee December 7, 2007

"Arthritis is one of the most common causes of knee pain in high level athletes, the weekend warrior, and in more sedentary individuals" says orthopedic surgeon, Dr. Scott Welsh. Arthritis is a process in which the cartilage that lines the bone initially starts to soften or crack. This is usually followed by roughening and thinning of the cartilage. The cartilage continues to break down until there is exposed bone. Osteoarthritis is a complex process which is still poorly understood. Multiple factors contribute to the development of arthritis including ligament damage, cartilage injuries, fractures of the knee joint, obesity, and genetics.

Osteoarthritis is simply the wear and tear on the cartilage of your joints usually related to the aging process or to previous injuries. Recent research has found that this type of arthritis may be inherited as well. This form of arthritis usually occurs gradually in the middle aged and elderly populations but can occur in younger patients after severe injuries.

Rheumatoid arthritis is an inflammatory form of arthritis and is usually not the result of an injury. It is more common in females and usually presents at a much earlier age than osteoarthritis. It tends to affect joints symmetrically and is the more disabling form of arthritis. Rheumatoid arthritis very commonly will run in families.

What are the symptoms of osteoarthritis?

Pain: Most patients describe an achey discomfort but the pain may be sharp, stabbing, burning, or throbbing. For some people, the pain may be worse at rest but improve after standing and walking. As the arthritis progresses the pain will become worse at rest and with activity.
Stiffness: Your joints may feel stiff especially when sitting or after getting out of bed in the morning.
Swelling: Arthritis can cause swelling in joints which may cause a sense of tightness while bending your knee. Swelling is usually more pronounced after activities.
Deformed joints: Bowing of the legs or developing "knock-knees" is a sign of more advanced arthritis. Rheumatoid arthritis typically causes more joint deformity in the hands and wrists.
Cracking and grinding: Your joints may make crunching, popping, or grinding sounds.

Diagnosis

The diagnosis of osteoarthritis can be made by a careful history and physical examination, weight bearing x-ray studies, and MRI. Subtle narrowing of the joint may be missed if standing x-rays are not performed. MRI can also be used to diagnose arthritis, but is particularly helpful to rule out other sources of pain, especially tears in the meniscus, which are commonly associated with arthritis.

Treatment of osteoarthritis of the knee should follow a step-wise approach starting with the least invasive treatments.

Patients should initially try supplements such as glucosamine and chondroitin as they have been found to decrease pain when taken for four to six weeks consecutively.
A low impact exercise program such as cycling, swimming, elliptical trainers, and rowing machines can decrease pain because of the natural lubricating effects of exercise on the joint.
A strengthening program and physical therapy are also very beneficial to decrease arthritis pain.
Tylenol (acetaminophen) is recommended for pain if the supplements and the exercise program are ineffective.
Anti-inflammatory medication (NSAIDs) such as Motrin, Advil, Celebrex, and Aleve are also very helpful for arthritis pain but must be used cautiously due to potentially serious side effects.
A variety of braces can be used to give some relief as well. Weight loss and avoidance of impact activity can also be beneficial.

"If a patient has failed the above treatment options then I consider injections as the next step," says Dr. Welsh. "Two types of injections exist for the knee, cortisone and viscosupplementation injections. Cortisone works essentially as a potent anti-inflammatory within the knee and will typically give temporary and partial relief of pain within 3-5 days. Cortisone should be limited to a maximum of three injections per year because of potential harmful effects to the joint cartilage. I typically will use cortisone when a patient presents with an acute exacerbation of their pain and is in need of rapid relief. The duration of it's effect is unpredictable."

Viscosupplementation is a term used to describe a series of "lubrication" injections administered once a week for 3-5 weeks consecutively, depending on the manufacturer. These injections have been approved in the United States since 1997. The active ingredient within all of the medications is hyaluronic acid which is a building block of our joint cartilage and our joint (synovial) fluid. Normal joint fluid is fairly viscous (thick like cooking oil) as compared to the fluid in an arthritic knee which loses it's viscosity and elasticity, becoming more water-like.

The injections are believed to work by several mechanisms. The medication is designed to repeatedly stimulate the joint lining to produce joint fluid with better viscous properties. "The medication will usually start taking effect within two to three weeks of the first injection and the maximum response is after four to six weeks. The injections will last on average about six months and occasionally longer. Many patients will only get 3-4 months of relief," says Dr. Welsh. Multiple studies have shown a success rate of approximately 50 -75% with the injections. They may be repeated every six months if needed and can be used indefinitely. The most common side effect is injection site pain which usually subsides within 24 hours.

If the injections are ineffective or the MRI shows pathology necessitating surgery such as a meniscal tear then an outpatient arthroscopy may be beneficial to smooth out the cartilage depending on the degree of arthritis. If the arthritis is advanced with bone on bone deformity then either a partial or total knee replacement may be warranted. Cartilage replacement techniques may be used also to regenerate cartilage but only if the there is a well defined defect in the cartilage. Arthritis tends to be more diffuse usually therefore not amenable to cartilage replacement.

Scott A. Welsh, MD specializes in sports medicine and general orthopedics. He has a particular interest in arthroscopic cartilage restoration procedures of the knee. Dr. Welsh received his undergraduate degree from the University of Illinois and attended medical school at Loyola University Chicago. He then completed his orthopedic residency at Michigan State University and his sports medicine fellowship at the Florida Orthopedic Institute in Tampa. He has worked as a team physician for the University of South Florida, University of Tampa, Western Michigan University, Saint Leo University, and several high schools in the Tampa area.

Appointments: 512-301-9922

Cypress Creek Orthopedics & Sports Medicine

Seton Southwest Hospital Medical Plaza

7900 FM 1826 Suite 170

Austin, TX 78737

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