When Partial Knee Replacement Fails, Do Another?

When there is progressive osteoarthritis after a partial knee arthroplasty, is it better to revise to a total knee arthroplasty or do an additional partial? A multicenter team collected relevant data and published the results of their study, titled; “Staged BiCompartmental Knee Arthroplasty has Greater Functional Improvement, but Equivalent Midterm Survivorship, as Revision TKA for Progressive Osteoarthritis After Partial Knee Arthroplasty,” in the July 1, 2022 edition of The Journal of Arthroplasty.

Jess H. Lonner, M.D. orthopedic surgeon at the Rothman Orthopaedic Institute and professor of Orthopaedic Surgery, Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia and co-author told OTW, “There is growing interest in partial knee arthroplasty, in general, for its myriad benefits (lower perioperative risks, more normal feeling knee, quicker recovery). And while the typical treatment when a partial knee fails due to progressive knee arthritis is conversion to a total knee, it has seemed to me that in those patients with a well-functioning partial knee that is not itself loose or worn, adding another partial knee to the other compartment, is a reasonable, but relatively unstudied option.”

“We hypothesized that in well performed partial knees, the implants themselves are quite durable and the risk of failure of the partial knee implant—if the other compartment is secondarily resurfaced—is likely low. We also hypothesized that compared to revision to a total knee, the option of a ‘staged bicompartmental’ may also capitalize on the traditional benefits of a partial knee…oh and also, they would be suitable to do in an ambulatory surgery center, which as you know, is the preference now for so many surgeons and patients.”

For patients with an intact partial knee arthroplasty who had no loosening or wear, the researchers collected data from 27 patients treated with staged bicompartmental knee arthroplasty and then 30 patients who had received a revised total knee arthroplasty for progressive osteoarthritis.

The team found that the mean time to conversion was 7.4 ± 6 years for staged bicompartmental knee arthroplasty and 9.7 ± 8 for a revised TKA. Staged bicompartmental knee arthroplasty patients took, on average, 5.7 ± 3 years and for revised TKA cases it was 3.2 ± 2 years. The Knee Injury and Osteoarthritis Outcome Score, Jr. significantly improved by an equivalent amount.

Both the post-operative Knee Society Function and Objective Scores were significantly higher for patient who had had staged bicompartmental knee arthroplasty versus those who were treated with a revised TKA, respectively, (90.4 ± 10 vs 72.1 ± 20) and (80.3 ± 18 vs 67.1 ± 19).

Those in the staged bicompartmental knee arthroplasty group experienced significantly greater improvement in Knee Society Objective Scores (30.7 ± 33 vs 5.2 ± 18).

“Surgical times and length of stay were markedly reduced in the staged bicompartmental group compared to revision TKA group,” Dr. Lonner told OTW. “Implant durability/survivorship were comparable between groups; by some parameters there was greater improvement in functional outcomes in the staged bicompartmental group.”

“Given the improved outcomes and quicker surgery, as more surgeons become facile with partial knee arthroplasty techniques, surgeons may give greater consideration to doing a staged bicompartmental when a partial knee is intact, but ‘fails’ due to progressive arthritis. This is a safe and effective option, and while we did not do a formal cost analysis, it can also represent a considerable cost savings, particularly when considering time driven activity-based costing analyses that factor in OR time, length of stay, implant costs, etc.”