e174(1) C OPYRIGHT Ó 2013
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty Among Medicare Beneficiaries, 2000 to 2009 Michael P. Bolognesi, MD, Melissa A. Greiner, MS, David E. Attarian, MD, Tyler Steven Watters, MD, Samuel S. Wellman, MD, Lesley H. Curtis, PhD, Keith R. Berend, MD, and Soko Setoguchi, MD, DrPH Investigation performed at the Duke Clinical Research Institute, Durham, North Carolina
Background: Unicompartmental knee arthroplasty is a less-invasive alternative to total knee arthroplasty for patients with arthritis affecting only the medial or lateral compartment. However, little is known about recent trends in the use of these procedures and the associated outcomes among older patients. Methods: With use of a nationally representative 5% sample of Medicare beneficiaries who were sixty-five years of age or older and who had undergone either unilateral unicompartmental knee arthroplasty or unilateral total knee arthroplasty from 2000 to 2009, we assessed trends in the use of unicompartmental and total knee arthroplasty, associated durations of hospital stay, and postoperative outcomes. The outcome measures were the rates of implant revision or removal within five years and the rates of periprosthetic infection, thromboembolic events, myocardial infarction, and allcause mortality within one year. We conducted Kaplan-Meier analyses to assess the cumulative incidence of unadjusted outcomes and used Cox proportional-hazards regression to understand the relative risks of the outcomes for each procedure. Results: A total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unilateral unicompartmental knee arthroplasty (n = 3098) from 2000 to 2009. The mean age was seventy-five years; 34% of the patients were men, and 92% were white. The procedure rate was twenty-one times higher for total knee arthroplasty (597 per 100,000 person-years) than unicompartmental knee arthroplasty (twenty-nine per 100,000 person-years). The use of total knee arthroplasty increased 1.7-fold, and the use of unicompartmental knee arthroplasty increased 6.2-fold. The mean length of stay (and standard deviation [SD]) was 3.9 ± 2.1 days for total knee arthroplasty and 2.4 ± 1.7 days for unicompartmental knee arthroplasty. The five-year revision rate was 3.7% for total knee arthroplasty and 8.0% for unicompartmental knee arthroplasty. After multivariable adjustment, the risk of revision remained 2.4 times higher for unicompartmental knee arthroplasty than for total knee arthroplasty (95% confidence interval [CI] = 2.03 to 2.83). After multivariable adjustment, patients who underwent unicompartmental knee arthroplasty had no significant differential oneyear risk of infection (adjusted hazard ratio [HR] = 0.74; 95% CI = 0.55 to 1.01), thromboembolic events (adjusted HR =0.86; 95% CI = 0.57 to 1.29), or mortality (adjusted HR = 0.75; 95% CI = 0.50 to 1.11). Conclusions: Although unicompartmental knee arthroplasty accounted for only 4.5% of the unilateral knee replacements among Medicare beneficiaries, the use of this procedure has increased dramatically. Compared with those who had total knee arthroplasty, patients who underwent unicompartmental knee arthroplasty had higher revision rates but shorter durations of stay and tended to have lower rates of perioperative complications. These findings need to be confirmed by studies that incorporate detailed clinical information. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2013;95:e174(1-9)
d
http://dx.doi.org/10.2106/JBJS.L.00652
e174(2) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O LU M E 95 -A N U M B E R 22 N O V E M B E R 20, 2 013 d
d
d
J
oint replacement procedures, including knee arthroplasty, are among the more expensive procedures that are regularly performed among Medicare beneficiaries1. Unicompartmental knee arthroplasty has emerged as a less-invasive alternative to total knee arthroplasty for patients with limited arthritis who are thought to be candidates for partial joint replacement2. The potential advantages of unicompartmental knee arthroplasty include the preservation of bone stock, less surgical exposure, improved knee motion, better knee kinematics, a shorter operating time, lower blood loss and transfusion rates, a lower infection rate, shorter inpatient stay, faster recovery, and lower cost. However, the indications for unicompartmental knee arthroplasty remain controversial3. The classic recommendation is to restrict unicompartmental knee arthroplasty to patients who are older than sixty years of age and have unicompartmental osteoarthritis or focal osteonecrosis and who weigh
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty Among Medicare Beneficiaries, 2000 to 2009 Michael P. Bolognesi, MD, Melissa A. Greiner, MS, David E. Attarian, MD, Tyler Steven Watters, MD, Samuel S. Wellman, MD, Lesley H. Curtis, PhD, Keith R. Berend, MD, and Soko Setoguchi, MD, DrPH Investigation performed at the Duke Clinical Research Institute, Durham, North Carolina
Background: Unicompartmental knee arthroplasty is a less-invasive alternative to total knee arthroplasty for patients with arthritis affecting only the medial or lateral compartment. However, little is known about recent trends in the use of these procedures and the associated outcomes among older patients. Methods: With use of a nationally representative 5% sample of Medicare beneficiaries who were sixty-five years of age or older and who had undergone either unilateral unicompartmental knee arthroplasty or unilateral total knee arthroplasty from 2000 to 2009, we assessed trends in the use of unicompartmental and total knee arthroplasty, associated durations of hospital stay, and postoperative outcomes. The outcome measures were the rates of implant revision or removal within five years and the rates of periprosthetic infection, thromboembolic events, myocardial infarction, and allcause mortality within one year. We conducted Kaplan-Meier analyses to assess the cumulative incidence of unadjusted outcomes and used Cox proportional-hazards regression to understand the relative risks of the outcomes for each procedure. Results: A total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unilateral unicompartmental knee arthroplasty (n = 3098) from 2000 to 2009. The mean age was seventy-five years; 34% of the patients were men, and 92% were white. The procedure rate was twenty-one times higher for total knee arthroplasty (597 per 100,000 person-years) than unicompartmental knee arthroplasty (twenty-nine per 100,000 person-years). The use of total knee arthroplasty increased 1.7-fold, and the use of unicompartmental knee arthroplasty increased 6.2-fold. The mean length of stay (and standard deviation [SD]) was 3.9 ± 2.1 days for total knee arthroplasty and 2.4 ± 1.7 days for unicompartmental knee arthroplasty. The five-year revision rate was 3.7% for total knee arthroplasty and 8.0% for unicompartmental knee arthroplasty. After multivariable adjustment, the risk of revision remained 2.4 times higher for unicompartmental knee arthroplasty than for total knee arthroplasty (95% confidence interval [CI] = 2.03 to 2.83). After multivariable adjustment, patients who underwent unicompartmental knee arthroplasty had no significant differential oneyear risk of infection (adjusted hazard ratio [HR] = 0.74; 95% CI = 0.55 to 1.01), thromboembolic events (adjusted HR =0.86; 95% CI = 0.57 to 1.29), or mortality (adjusted HR = 0.75; 95% CI = 0.50 to 1.11). Conclusions: Although unicompartmental knee arthroplasty accounted for only 4.5% of the unilateral knee replacements among Medicare beneficiaries, the use of this procedure has increased dramatically. Compared with those who had total knee arthroplasty, patients who underwent unicompartmental knee arthroplasty had higher revision rates but shorter durations of stay and tended to have lower rates of perioperative complications. These findings need to be confirmed by studies that incorporate detailed clinical information. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2013;95:e174(1-9)
d
http://dx.doi.org/10.2106/JBJS.L.00652
e174(2) TH E JO U R NA L O F B O N E & JO I N T SU RG E RY J B J S . O RG V O LU M E 95 -A N U M B E R 22 N O V E M B E R 20, 2 013 d
d
d
J
oint replacement procedures, including knee arthroplasty, are among the more expensive procedures that are regularly performed among Medicare beneficiaries1. Unicompartmental knee arthroplasty has emerged as a less-invasive alternative to total knee arthroplasty for patients with limited arthritis who are thought to be candidates for partial joint replacement2. The potential advantages of unicompartmental knee arthroplasty include the preservation of bone stock, less surgical exposure, improved knee motion, better knee kinematics, a shorter operating time, lower blood loss and transfusion rates, a lower infection rate, shorter inpatient stay, faster recovery, and lower cost. However, the indications for unicompartmental knee arthroplasty remain controversial3. The classic recommendation is to restrict unicompartmental knee arthroplasty to patients who are older than sixty years of age and have unicompartmental osteoarthritis or focal osteonecrosis and who weigh
