What patients want to know about joint replacement
The question patients most often ask both their referring physician and the orthopedic surgeon is, “How long will my joint replacement last?” The best available data come from a couple of recent paired meta-analyses. The investigators reported 82% implant survivorship 25 years after primary total knee arthroplasty and 70% after unicondylar knee arthroplasty as well as a 25-year implant survivorship rate of 77% for total hip arthroplasty.
“I expected that hip arthroplasty survivorship rate to be much higher than 77%. The reason it’s not is probably because of the metal-on-metal bearing surface debacle of about 10 years ago. There’ve been lots of revisions because of that. We thought metal-on-metal implants were going to be all that, with microscopically low wear, but they turned out to be a nightmare because of metal ion release,” Dr. Bugbee observed.
The long-term joint survivorship data are based upon older implants. Encouraging albeit still preliminary data suggest contemporary implants may last significantly longer. The “clear winner,” he said, is a 36-mm ceramic head and a highly crosslinked polyethylene liner.
“That’s been a game changer, with a 10- to 20-fold decrease in wear compared to plastics for weight-bearing surfaces,” Dr. Bugbee said.
In terms of functional improvement, by various measures 85%-97% of patients are satisfied with the results of their total hip replacement, and 60% report returning to high-level recreational activities. Patient satisfaction scores are lower – 75%-90% – after total knee arthroplasty.
“The total knee replacement just doesn’t work like a regular joint,” the surgeon observed. “When I think of hip and knee replacements, I think of a hip as a Ferrari – it’s a high-performance joint replacement – and I think of the knee as a Ford – it’s serviceable, it does the job, and it’s okay but not fantastic.”
How referring physicians can optimize preoperative management and long-term follow-up
Orthopedic surgeons would appreciate help from rheumatologists and primary care physicians in preoperatively addressing the known modifiable risk factors for poor outcomes of joint replacement. These include obesity, smoking, depression, a hemoglobin A1c of 7% or more, and being on opioids. These risk factors are incompatible with outpatient hip or knee replacement.
“Let the surgeon know if you think outpatient joint replacement is a bad idea in your patient for medical reasons,” Dr. Bugbee urged.
Also, orthopedic surgeons can generally benefit from rheumatologist input regarding perioperative management of patients on standard disease-modifying antirheumatic drugs, biologics, or Janus kinase inhibitors as recommended in the guidelines published jointly by the American College of Rheumatology and the American Association of Hip and Knee Surgeons.
“I can guarantee you that most orthopedic surgeons don’t know about these guidelines. The evidence base for these recommendations is not great, but these are the best guidelines we have,” Dr. Bugbee said.
After joint replacement surgery a patient should get an x-ray of the replacement every 5 years. And if a patient develops a painful hip after arthroplasty, it’s worthwhile to order blood chromium and cobalt levels.
“The implant weight-bearing surface matters. You can’t necessarily tell on x-ray what’s a metal-on-metal hip and what’s metal-on-plastic or ceramic. You already send people for a lot of labs. If you see a patient with a painful total hip replacement, just add a cobalt and chromium. If they’re elevated, talk to the orthopedist,” he advised.