The National Surgical Quality Improvement Program (NSQIP) database contains more than a half-million records of patients who received a total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or total hip arthroplasty (THA) from 2009 through 2018. Fewer than 4% of those procedures were done in an outpatient setting, but patient demand for outpatient arthroplasty is rising rapidly.
With retrospective data like that from NSQIP, the most meaningful comparisons between inpatient and outpatient procedures come through a propensity score-matched analysis. Propensity score matching pairs up patients in each group according to multiple factors thought to influence outcome. In a recent study in The Journal of Bone & Joint Surgery, Lan et al. used propensity score matching to compare inpatient and outpatient arthroplasty in terms of adverse events and readmissions.
What the Researchers Did:
- Matched each outpatient case of TKA, UKA, and THA from the database with 4 unique inpatient cases based on age, sex, ASA class, race, BMI, type of anesthesia, and history of hypertension, smoking, congestive heart failure, and diabetes
- Compared inpatient vs outpatient rates of 30-day adverse events (both minor and severe) and readmissions
- Identified risk factors for adverse events and readmissions
What the Researchers Found:
- For all 3 arthroplasty types, patients who underwent an outpatient procedure were less likely to experience any adverse event, when compared with those who underwent an inpatient procedure.
- The above adverse-event findings held true when TKAs, UKAs, and THAs were analyzed separately.
- Outpatient procedure status was an independent protective factor against the risk of adverse events.
- For all 3 procedures, readmission rates were similar among inpatients and outpatients. (The 2 most common reasons for readmission were infections and thromboembolic events.)
- Clinicians are probably (and reasonably) selecting healthier patients to undergo outpatient procedures, but 42% of the outpatient cohort had an ASA class ≥3, and 55% had a BMI ≥30 kg/m2.
In their abstract, the authors cited “increased case throughput” as one rationale for outpatient arthroplasty, but this study provides convincing evidence that adverse-event reduction is another compelling reason for certain patients to consider outpatient knee and hip procedures.
Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all such OrthoBuzz specialty-update summaries.
This month, author Michael J. Taunton, MD summarizes the 5 most compelling findings from the 130 studies highlighted in the January 20, 2021 “What’s New in Adult Reconstructive Knee Surgery.”
Waiting for a Knee Replacement
–Patient wait times for joint arthroplasty, exacerbated in many places by the COVID-19 pandemic, continue to increase. As measured by the EQ-5D, the health among 12% of 2,168 patients awaiting total knee arthroplasty (TKA) in a recent cross-sectional analysis was rated as “worse than death.”1 Joint-specific function and various comorbidities were associated with these findings.
UKA vs TKA
–The multicenter randomized TOPKAT trial2 compared unicompartmental knee arthroplasty (UKA) with TKA for treating medial compartment osteoarthritis. At the 5-year follow-up, there was no between-group difference in Oxford knee scores, but UKA was more cost-effective and provided an additional 0.24 quality-adjusted life year.
Perioperative Patient Optimization
–An observational study analyzing >1,000 total joint arthroplasties3 found that implementing a “perioperative orthopaedic surgical home”—a surgeon-led screening and optimization initiative targeting 8 common modifiable comorbidities—resulted in a 1.6% 30-day readmission rate (versus 5.3% among patients not involved in the initiative).
Pain Management and Opioids
–A randomized controlled trial of >300 patients undergoing primary total knee or hip arthroplasty4 demonstrated that reducing the number of 5-mg oxycodone pills prescribed at discharge from 90 to 30 resulted in the following findings 30 days postoperatively:
- Similar between-group pain scores
- No between-group differences in patient-reported outcomes
- Significant reductions in unused opioid pills and in pain pills taken in the 30-pill group
Periprosthetic Joint Infection
–Patients undergoing primary TKA who had a history of periprosthetic joint infection (PJI) in another joint had a significantly higher risk of PJI after the primary TKA, compared with the risk among a matched cohort with no history of PJI.5
- Scott CEH, MacDonald DJ, Howie CR. ‘Worse than death’ and waiting for a joint arthroplasty. Bone Joint J.2019 Aug;101-B(8):941-50.
- Beard DJ, Davies LJ, Cook JA, MacLennan G, Price A, Kent S, Hudson J, Carr A, Leal J, Campbell H, Fitzpatrick R, Arden N, Murray D, Campbell MK; TOPKAT Study Group. The clinical and cost-effectiveness of total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. 2019 Aug 31;394(10200):746-56. Epub 2019 Jul 17.
- Kim KY, Anoushiravani AA, Chen KK, Li R, Bosco JA, Slover JD, Iorio R. Perioperative orthopedic surgical home: optimizing total joint arthroplasty candidates and preventing readmission. J Arthroplasty.2019 Jul;34(7S):S91-6. Epub 2019 Jan 18.
- Hannon CP, Calkins TE, Li J, Culvern C, Darrith B, Nam D, Gerlinger TL, Buvanendran A, Della Valle CJ. The James A. Rand Young Investigator’s Award: large opioid prescriptions are unnecessary after total joint arthroplasty: a randomized controlled trial. J Arthroplasty.2019 Jul;34(7S):S4-10. Epub 2019 Feb 4.
- Chalmers BP, Weston JT, Osmon DR, Hanssen AD, Berry DJ, Abdel MP. Prior hip or knee prosthetic joint infection in another joint increases risk three-fold of prosthetic joint infection after primary total knee arthroplasty: a matched control study. Bone Joint J.2019 Jul;101-B(7_Supple_C):91-7.
These operations were performed by a group of fairly experienced surgeons who averaged >14 UKAs per year, although a commonly used threshold for a “high-volume” UKA surgeon is >15 procedures per year. The cumulative revision rate of 14.2% over 8.7 years, the 5-year Kaplan-Meier survival rate of 88%, and the 10-year survival rate of 70% found by Kazarian et al. are disturbing. Using revision as an endpoint may be problematic because some surgeons are quick to revise a UKA when the radiographic evaluation of component placement is not perfect. Still, this study demonstrates that radiographically determined alignment and overhang “outliers” and “far outliers” had a significantly increased risk of implant failure, compared with patients with good alignment and overhang.
This study did not include UKAs that used computer-assisted methods, but it seems safe to conclude that computer-assisted component placement would be more reliable than “eyeballing,” especially among surgeons with less-experienced eyes. Based on this and other recent studies, I think a controlled trial comparing the functional outcomes and revision rates of UKAs performed with and without computer assistance is warranted.
Marc Swiontkowski, MD
Editor’s Note: Click here to read the JBJS Clinical Summary on Unicompartmental Knee Arthroplasty.
Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of OrthoBuzz summaries of these “What’s New” articles. This month, author Michael J. Taunton, MD selected the 5 most clinically compelling findings from the more than 130 studies summarized in the January 15, 2020 “What’s New in Adult Reconstructive Knee Surgery.”
Unicompartmental Knee Arthroplasty (UKA)
—A prospective cohort study of 1,000 Oxford cementless UKAs indicated by standard Kozinn and Scott criteria found that revision-free survivorship at 10 years was 97%. Progression of lateral osteoarthritis and dislocation of the bearing were the most common reasons for revision.1
—Authors of a double-blinded, prospective, randomized study assigned 60 primary total knee arthroplasty (TKA) patients to receive either a continuous adductor canal block or a single-injection adductor canal block with adjuvant agents. They found no between-group differences in pain scores up to 42 hours postoperatively.2
Post-TKA Physical Therapy (PT)
—A prospective, randomized, noninferiority trial demonstrated that 290 post-TKA patients who were randomized to either outpatient PT, unsupervised web-based PT at home, or unsupervised printed-instruction-based PT at home had no difference in knee range of motion or in patient-reported outcomes at 4 to 6 weeks or 6 months postoperatively.3
—In a retrospective review of 29,695 total joint arthroplasties, preoperative penicillin allergy testing led to a 1.19% higher rate of infection-free survival at 10 years, principally by allowing more routine use of the prophylactic antibiotic cefazolin.4
—A retrospective case series found that patients undergoing revision TKA at an age of < 50 years had a survivorship free of re-revision of 66% at 10 years. Regardless of the reason for revision, this population also had a higher risk of mortality than the general population at 10 years.5
- Campi S, Pandit H, Hooper G, Snell D, Jenkins C, Dodd CAF, et al. Ten-year survival and seven-year functional results of cementless Oxford unicompartmental knee replacement: A prospective consecutive series of our first 1000 cases. Knee. 2018 Dec;25(6):1231-7. Epub 2018/08/29.
- Turner JD, Dobson SW, Henshaw DS, Edwards CJ, Weller RS, Reynolds JW, et al. Single-Injection Adductor Canal Block With Multiple Adjuvants Provides Equivalent Analgesia When Compared With Continuous Adductor Canal Blockade for Primary Total Knee Arthroplasty: A Double-Blinded, Randomized, Controlled, Equivalency Trial. J Arthroplasty. 2018 Oct;33(10):3160-6 e1. Epub 2018/06/16.
- Fleischman AN, Crizer MP, Tarabichi M, Smith S, Rothman RH, Lonner JH, et al. 2018 John N. Insall Award: Recovery of Knee Flexion With Unsupervised Home Exercise Is Not Inferior to Outpatient Physical Therapy After TKA: A Randomized Trial. Clin Orthop Relat Res. 2019 Jan;477(1):60-9. Epub 2019/02/23.
- Wyles CC, Hevesi M, Osmon DR, Park MA, Habermann EB, Lewallen DG, et al. 2019 John Charnley Award: Increased risk of prosthetic joint infection following primary total knee and hip arthroplasty with the use of alternative antibiotics to cefazolin: the value of allergy testing for antibiotic prophylaxis. Bone Joint J. 2019 Jun;101-B(6_Supple_B):9-15. Epub 2019/05/31.
- Chalmers BP, Pallante GD, Sierra RJ, Lewallen DG, Pagnano MW, Trousdale RT. Contemporary Revision Total Knee Arthroplasty in Patients Younger Than 50 Years: 1 in 3 Risk of Re-Revision by 10 Years. J Arthroplasty. 2019 Jul;34(7S):S266-S70. Epub 2019/03/03.
Along with recently renewed interest in unicompartmental knee arthroplasty (UKA) has come debate as to whether the preoperative presence of patellofemoral osteoarthritis (OA) and/or abnormal patellofemoral alignment should be considered UKA contraindications. Findings from a retrospective review of 639 knees by Burger et al. in the September 18, 2019 issue of The Journal of Bone & Joint Surgery strongly suggest that the answer is “no.”
After examining preoperative radiographic OA and alignment characteristics and postoperative patient-reported outcomes among patients who underwent fixed-bearing medial UKA, the authors concluded that “neither the [radiographic] presence of preoperative mild to moderate [patellofemoral] osteoarthritis nor abnormal patellar tilt or congruence compromised [patient-reported knee and patellofemoral-specific] outcomes at intermediate-term follow-up [mean of 4.3 ±1.6 years].”
Expanding the surgical inclusion criteria for UKA based on these findings could increase the number of patients eligible for UKA by 20% to 40%, estimated Burger et al. In the practice of the senior author (Andrew D. Pearle, MD), patients with symptoms of patellofemoral OA (such as anterior knee pain with prolonged sitting or stair-climbing) are considered ineligible for UKA, prompting the authors to suggest that “the presence of such symptoms may be better than radiographic criteria for determining which patients are eligible for medial [UKA].”
Surgical treatment for knee osteoarthritis (OA) has become increasingly common. The many people who have damage to only one part of their joint (unicompartmental knee OA) are faced with three options—total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or nonsurgical treatment. A study by Kazarian et al. in the October 3, 2018 issue of The Journal estimates the lifetime cost-effectiveness for those three options in patients from 40 to 90 years of age.
The authors used sophisticated computer modeling to estimate both direct costs (those related to medical/surgical care) and indirect costs (such as missed workdays) of the three options as a function of patient age at the time of treatment initiation. Here are the key findings:
- The surgical treatments were less expensive and provided patients from 40 to 69 years of age with a greater number of quality-adjusted life years (QALYs) than nonsurgical treatment.
- In patients 70 to 90 years of age, surgical treatments were still cost-effective compared with nonsurgical treatment, albeit less so than in younger patients. In this older age group, “cost-effectiveness ratios” of surgical treatment remained below a “willingness to-pay” threshold of $50,000 per QALY.
- When the two surgical treatments were compared to one another, UKA beat TKA decisively in cost-effectiveness among patients of any age.
After crunching more numbers, Kazarian et al. estimated that, by 2020, if all of the patients with unicompartmental knee OA who were candidates for UKA or TKA (a projected total of 120,000 to 210,000 people) received UKA, “it would lead to a lifetime cost savings of $987 million to $1.5 billion.
From these findings, the authors conclude that patients with unicompartmental knee OA should receive surgical treatment, preferably UKA, instead of nonsurgical treatment until the age of 70 years. After that age, all three options are reasonable from a cost-effectiveness perspective.
But perhaps the most important thing to remember about these findings is that they add information to—but should not replace—clinical decision-making based on complete and open communication between doctor and patient.
The recently launched JBJS Knee Spotlight offers highly relevant and potentially practice-changing knee content from the most trusted source of orthopaedic information.
Here are the five JBJS articles to which you will have full-text access through the Knee Spotlight during the month of March 2017:
- Improved Accuracy of Component Positioning with Robotic-Assisted Unicompartmental Knee Arthroplasty: Data from a Prospective, Randomized Controlled Study
- The Effect of Timing of Manipulation Under Anesthesia to Improve Range of Motion and Functional Outcomes Following Total Knee Arthroplasty
- Anatomic Single-Bundle ACL Reconstruction Is Possible with Use of the Modified Transtibial Technique: A Comparison with the Anteromedial Transportal Technique
- Autologous Chondrocyte Implantation in the Knee: Mid-Term to Long-Term Results
- Outcomes of Unicompartmental Knee Arthroplasty After Aseptic Revision to Total Knee Arthroplasty: A Comparative Study of 768 TKAs and 578 UKAs Revised to TKAs from the Norwegian Arthroplasty Register (1994 to 2011)
Knee studies offered on the JBJS Knee Spotlight will be updated monthly, so check the site often.
In the January 18, 2017 issue of JBJS, Krych et al. report on early and mid-term results of the two most common surgical procedures to help patients 55 years old and younger with varus knees and medial compartment osteoarthritis: unicompartmental knee arthroplasty (UKA) and proximal tibial osteotomy (PTO). PTO realigns the knee’s biomechanics by moving the weight-bearing line laterally toward the more normal side of the knee. UKA corrects the biomechanical issue and removes and resurfaces damaged tissue.
In this comparative cohort study of 240 patients between 18 and 55 years old, patients receiving UKA had better functional scores and reached a higher activity level early after surgery. UKA survivorship (defined as avoiding revision to total knee arthroplasty [TKA]) was 94% at an average of 5.8 years, while PTO survivorship was 77% at an average of 7.2 years.
The functional outcomes should come as no surprise, seeing as arthroplasty replaces/denervates the subchondral bone in the medial compartment, while also correcting the alignment issue. A reasonable trauma-related analog to this can be seen with total hip arthroplasty providing generally better functional outcomes for displaced femoral neck fractures than internal fixation because the latter approach does not anatomically restore hip biomechanics. In both those cases, the mechanics of a weight-bearing joint are maintained/improved without relying on bone to heal. In contrast, with PTO and other bone and joint “preservation” approaches, the natural mechanics are altered.
However, I do not think we should extend this argument beyond what these data from Krych et al. provide. The mean length of follow-up in the UKA group was only 5.8 years. We need 20- to 30-year results in that group so we can truly understand the risk of further arthroplasty revision, polyethylene replacement, periprosthetic fracture, etc. I therefore truly hope to see follow-up reporting in a decade on this cohort of patients.
We must also recognize that these patients were selected for a surgical intervention based on their functional demand. The baseline characteristics of both groups suggest that those who had higher loading “habits” received an osteotomy.
Marc Swiontkowski, MD
Many surgeons recommend primary unilateral knee arthroplasty (UKA) over primary total knee arthroplasty (TKA) or tibial osteotomy for younger patients with unicompartmental knee osteoarthritis. Some do so believing that the results of any subsequent revision to TKA (UKA → TKA) will be better than a revision of a primary TKA to a second TKA (TKA → TKA).
A comparative, registry-based study by Leta et al. in the March 16, 2016 JBJS found that both revision categories yielded essentially the same outcomes. The authors found no significant differences between the two strategies in terms of overall implant survival rate or risk of re-revision, or in several patient-reported outcomes: the EuroQol EQ-5D, KOOS, and VAS pain and satisfaction scores. Two notable exceptions were as follows:
- The risk of re-revision was twice as high for TKA → TKA patients who were older than 70 years of age
- UKA → TKAs were more often re-revised because of a loose tibial component and pain alone, while TKA → TKAs were more often re-revised because of deep infection.
With few significant outcome differences, commentator Geoffrey Dervin, MD suggests that “patients facing the initial decision between UKA and TKA should focus more on differences in perioperative morbidity, clinical outcomes, and satisfaction” from the primary procedure rather than on the outcomes of revision should it be required.