The current literature about revision total knee arthroplasty (rTKA) for aseptic causes is focused mainly on “doctorly” data such as complication rates and implant survivorship. Taking a different tack in the October 21, 2020 issue of JBJS, Siddiqi et al. report findings from a comprehensive evaluation of patient-reported outcome measures (PROMs) at baseline and 1 year following rTKA. The PROMs evaluated included KOOS-Pain, KOOS-Physical Function, KOOS-QOL, and Veterans Rand-12.
Here is a general summary of the findings:
- Patients undergoing aseptic rTKA had overall improvements in pain and function scores at 1 year postoperatively.
- Knee-related QOL improved nearly 30 points, but >50% of patients did not report improvement in their overall global health at 1 year.
- Predictors of improved 1-year pain scores were older age, baseline arthrofibrosis, lower baseline pain, and non-Medicare/Medicaid insurance.
- Predictors of improved 1-year function scores were baseline arthrofibrosis and female sex.
- Larger mean pain-score improvements occurred in patients undergoing rTKA for implant failure and aseptic loosening; pain-score improvements were lower in patients undergoing rTKA for instability.
Although 31% of the 246 eligible patients were lost to follow-up and excluded from the final analysis, the authors say their findings “corroborate the overall quality and, most importantly, the value that aseptic rTKA provides to patients.” Perhaps the findings’ greatest value is their potential application in the shared decision-making process between surgeons and patients pondering an aseptic rTKA, and in helping set realistic patient expectations if the surgery is undertaken.
Time is a valuable commodity for everyone. Most physicians have spent long hours in the clinic or hospital, away from our families, sometimes missing important life events. We accept those aspects of our chosen profession. But everyone, including surgeons, wants to be appropriately reimbursed for their time. It’s logical that more complex surgical cases take more time to perform correctly and safely. But does Medicare (and the private insurers who base their physician payments on Medicare rates) adequately reimburse for that extra time?
The short answer is “no,” at least in terms of revision surgery for infected total knee arthroplasties (TKAs). Samuel et al. tackle that topic in the February 5, 2020 issue of The Journal. The authors reviewed records from the NSQIP database to identify cases of aseptic revision TKA, 1-stage septic revision TKA, and 2-stage septic revision TKA. Using propensity-score matching that controlled for age, sex, race, BMI, and ASA classification, the authors established 4 cohorts that allowed for comparison of the following types of revision TKA:
- 1-stage, 2-component aseptic revisions (n=1,096)
- 1 stage, 2-component septic revisions (n=274)
- First stage of a 2-stage septic revision (n=274)
- Second stage of a 2-stage septic revision (n=274)
The authors then compared the relative value units (RVUs) for each type of revision TKA. (Medicare uses RVU-based algorithms to reimburse physicians for their services.) The authors also identified operative times for the surgery types and made RVU-per-minute and dollars-per-minute calculations.
The mean operative times were statistically different between each cohort (149 minutes for the aseptic group, 160 minutes for the 1-stage septic group, 138 minutes for the first-stage of the 2-stage septic group, and 170 minutes for the second-stage of the 2-stage septic group). The dollar-per-minute calculation in the “easiest case” of aseptic revision was $7.74 per minute, while in the “hardest case” of a 2-stage septic revision, reimbursement was $5.66 per minute for the first stage and $5.19 per minute for the second stage.
The fact that Medicare’s current reimbursement system does not account for the complexity of treating an infected TKA harms not only surgeons. Financially discouraging physicians from taking complex cases could lead to patients having a difficult time finding a doctor to treat their infected knee replacement. This entire predicament warrants further investigation, possible adjustments to the RVU system, and more realistic valuations of time in the OR.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
The main advantage of joint registries is their large number of recorded procedures, ideally with very few patient “types” not represented in the database. This is the case with the Australian Orthopaedic Association National Joint Replacement Registry, which includes data on almost 100% of all joint replacements performed in Australia since 2002. In the February 20, 2019 issue of The Journal, Jorgenson et al. analyze almost 6,000 major aseptic total knee arthroplasty (TKA) revisions from a cohort of 478,000 primary TKAs registered between 1999 and 2015. This analysis provides robust benchmark data for patients and surgeons, although it comes too late for the 3% of patients who required such a revision surgery within the 15-year study period.
The authors found that fixed bearings were revised for aseptic reasons at a significantly lower rate than mobile bearings (2.7% vs 4.1%, respectively) and that patients <55 years old had an almost 8-fold higher revision rate compared to patients ≥75 years old ( 7.8% versus 1.0%, respectively). The study also found lower aseptic revision rates with minimally stabilized total knee prostheses compared to posterior-stabilized prostheses, and higher aseptic revision rates with completely cementless fixation relative to either hybrid or fully cemented fixation. These are valuable data for arthroplasty surgeons in terms of selecting implants and surgical techniques and for preoperative counseling of patients—especially younger ones. While many of these findings have been previously reported, these registry-based results add significant strength to published data.
Ideally, data such as these would be controlled for confounding variables such as surgeon experience and additional patient-specific variables such as activity demands and medical comorbidities. Still, these data provide useful prosthesis-specific factors for shared decision making with patients. We look forward to more helpful information from this and other national joint registries and encourage the continued growth of similar registries in other subspecialties.
Marc Swiontkowski, MD