"Extreme" Knee Replacements Also Proving Successful

It's no news that total knee replacements (TKR) have increased dramatically-up about ninefold in people over age 65 between 1979 and 2006, according to one team reporting at the American Association of Orthopaedic Surgery annual meeting in Las Vegas.

What is new is the increasing numbers of people undergoing the procedure at both ends of the spectrum, the relatively young and unimpaired and the remarkably old. In both cases, judging from reports at AAOS2015, the results are satisfactory.

If you have been referring slender, healhy, well-educated Baby Boomers for knee replacement  because only moderate knee pain deters them from jogging or playing basketball, you're far from alone. A team at the University of Massachusetts in Worcester studied the characteristics of patients referred for TKR between 2011 and 2014, using data from a national cohort of knee-replacement patients at 22 sites nationwide. It showed that about 5% had low pain and high function (were able to climb stairs and sleep without pain), but noticed some pain or at least "awareness" of their knees every day.

Unlike the vast majority of TKRs ordered for severe pain or loss of function, about one in 20 are for these "quality of life" reasons, the team said.

Judging from a small observational study at a private clinic in Maryland, the results in younger patients are almost always excellent. Surgeon David Dalury of Towson Orthopaedics assessed the outcome of 60 consecutive patients aged 50 or younger who had TKRs between 1997 and 2006, 90% of them for osteoarthritis.

Only 6 of the 82 procedures (7%) required revision, at an average of 7 years post-surgery. Average Knee Society Society scores increased from 37 to 93 during the study period.

As to the other end of the spectrum, you can counsel patients over 90 years of age that in general their risks of complications from TKR are not significantly increased due to age alone.

Analysis of more than 50,000 TKR patients in a nationwide US surgical database showed that that, for those 90 or older, operations went significantly faster and led to significantly longer hospitalizations. But rates of complications such as infections or clotting or bleeding problems were not increased significantly.

This was true despite the fact that some preoperative red flags (dyspnea, hypertension, stroke without cogntive deficit, and bleeding disorders)  were significantly more common than among younger patients.

As to the small proportion who don't find relief from TKR, a prospective study from Singapore General Hospital offered one insight: Those who fare badly at six months post-surgery are unlikely to improve further.

The Singapore team used the Oxford Knee Score (OKS) to assess all patients who underwent unilateral TKR for primary osteoarthritis between mid-2004 and January 2012. Of the 260 who had poor outcomes (OKS <27) six months after emerging from surgery without complications, the group who scored <19 on the OKR at six months were significantly less likely to be symptom-free at two years.

Despite other similarities with the patients who fared better, this group also significantly worse preoperative scores, the team observed. Alas, at this one extreme-the greatest unexplained preoperative pain-the procedure doesn't seem to help at all.