Satisfaction Rate Extremely High After Total Knee Replacement

Fran Lowry

March 23, 2010

March 23, 2010 (New Orleans, Louisiana) — More than 95% of patients report that they are satisfied with the outcome of their total knee replacement 1 year after surgery, researchers announced here at the American Association of Orthopaedic Surgeons 2010 Annual Meeting.

Factors that increased risk for dissatisfaction were younger age, being female, valgus alignment of the knee, and posttraumatic arthritis, said David Christopher Ayers, MD, from the University of Massachusetts in Worcester.

"Knee replacement for relief of pain from osteoarthritis is currently one of the most common operations done in the United States," said Dr. Ayers. "Over 550,000 knee replacements are done per year, and the projected increase over the next 20 years is 400%."

This increase is being driven by the aging of the population, baby boomers who want to stay very active, and the increasing weight of the population, he said.

Being able to identify those who might be displeased beforehand could help clinicians counsel their patients about what to expect, and thus increase their satisfaction, Dr. Ayers noted.

To learn more about patient satisfaction after total knee replacement, Dr. Ayers and his team prospectively evaluated 7715 patients. Two thirds of the cohort was female and older than 65 years, 95% had a diagnosis of osteoarthritis, and 56% had a body mass index greater than 30 kg/m2.

The procedures were performed by 200 surgeons in 32 states from 2000 to 2004.

The mean age at preoperative baseline assessment was 68 years, mean Short-Form 36 Physical Functioning Scale (SF-36 PCS) score was 30, mean Emotional Functioning Scale (SF-36 MCS) score was 52, and mean Knee Society Pain Score was 37.

Prior to knee replacement, 52% of patients reported moderate or severe pain at rest, 88% reported moderate or severe pain when walking, and 77% could walk less than 5 blocks.

The study found that a lower SF-36 MCS score (<50) was significantly associated with dissatisfaction with total knee replacement (P = .001).

In addition, young and middle-aged patients (<70 years) reported significantly more dissatisfaction than older patients (5.4% vs 4.2%; P = .016).

Other factors were valgus malalignment (< .002), and either very good SF-36 PCS score (33–40) or very bad SF-36 PCS score (<30) at baseline, Dr. Ayers reported.

"This is real-life orthopaedics," Dr. Ayers said in an interview with Medscape Orthopaedics after his talk. "These procedures are not done in an academic institution ivory tower; this is what is happening in the United States right now."

The degree of satisfaction found in this study is higher than that in previous surveys, he added. "The other studies were done in the 1990s. It's also one of the largest studies. We didn't study the reasons that satisfaction with total knee replacement is increasing, but I think that the techniques have improved, the protocols have improved, and the prostheses have improved. All of these are possible reasons that patients are more satisfied," he said.

These results should be very reassuring to patients, said Clifford Colwell, MD, medical director at Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California.

"A lot of people ask if there is any guarantee that they will be better if they have total knee replacement. With these results, you can tell them that you don't have a guarantee, but statistically 95% at the end of 1 year are very satisfied. It's not 100%, but it's very good," Dr. Colwell, who was not part of the study, said.

No other type of surgery is associated with such high rates of satisfaction, he added. "There is nothing else that touches total knee replacement and total hip replacement surgeries. Not even cataract surgery."

Dr. Ayers and Dr. Colwell have reported no relevant financial relationships.

American Association of Orthopaedic Surgeons (AAOS) 2010 Annual Meeting: Abstract 431. Presented March 11, 2010.

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