Issue: July 2012
June 20, 2012
2 min read

Surgeon: Unicompartmental, total knees cannot be compared

Issue: July 2012
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The argument between total knee replacements and unicompartmental knee replacements may be as simple as the two being incomparable, according to a surgeon at the International Congress for Joint Reconstruction San Diego 2012 meeting, which was held in collaboration with Orthopedics Today.

“For the total knee, if we went way back to when this all started and predicted we would have 95%, 96% or 97% success rates at 20 years with various prostheses, everyone would have been ecstatic,” W. Norman Scott, MD, FACS, said during his presentation. “That is what we had at 20 years. But the underlying assumption in this uni argument is maybe a total knee is not indicated because if you have to revise a total knee, it is not a big deal … but is it really a substitute for a total?”

Scott said that when unicompartmental knee replacements (UKRs) were introduced, it was argued they may be better than high tibial osteotomy. He noted that his belief was UKRs did outperform high tibial osteotomies for arthritic patients, but comparing these to total knee replacements today is impossible.

“It makes no sense,” he said. “Comparisons always favor partial replacements, for the patients, when you look at preoperative deformities, range of motion — they are always worse in patients who go on to [total knee replacements] TKRs … but component loosening and survivorship rates for [UKR] are much higher than what you are seeing for the others.”

Scott also addressed what he considers misconceptions regarding UKR — including the notion that moving on to revision is not particularly difficult.

“Implicit in the uni argument was to not worry because if it does not work you can go on to do a revision, as it is not that hard. This is a myth,” he said, noting that revision-type component stems and wedges are being used in more than half of patients receiving UKRs.

“There is a place for unis, there is no question. It is in unilateral disease,” he said.


  • Scott WN. Don’t bother with a partial … TKA is the best. Presented at the International Congress for Joint Reconstruction San Diego 2012 in collaboration with Orthopedics Today. April 27-29. San Diego.
  • W. Norman Scott, MD, FACS, can be reached at 210 E 64th St., # 4, New York,  NY  10065-7471; email:
  • Disclosure: Scott receives royalties from Zimmer and Elsevier.