Genetic susceptibility to orthopaedic conditions is of interest to clinicians and patients alike. While the link between genetics and certain pediatric conditions is known, studies of sets of twins are providing new insights into adult issues, such as osteoarthritis, and the impact that genetics may have.
In the current issue of JBJS, Hailer et al. report on an investigation in Sweden in which they analyzed genetic susceptibility to hip and knee osteoarthritis necessitating total hip arthroplasty (THA) or total knee arthroplasty (TKA), and whether body mass index (BMI) moderates the heritability of these outcomes. They linked nearly 30,000 twin pairs with BMI information in the Swedish Twin Registry with the Swedish National Patient Register to identify twins who had undergone THA or TKA with a primary diagnosis of osteoarthritis. Structural equation modeling was then used to calculate the heritability of osteoarthritis treated with THA or TKA and how it related to BMI, age, and sex.
The authors note that, for radiographically defined knee osteoarthritis, previous twin studies have shown that the genetic susceptibility (“the proportion of the variation of a trait that can be attributed to the variation of genetic factors”) is between 0.4 to 0.8. In twin studies using total joint replacement as the outcome, heritability has been estimated to be 0.2 for TKA and 0.5 for THA.
Hailer et al. found that, on average in their cohort, approximately half of the susceptibility to undergo THA or TKA for osteoarthritis was explained by heritability, with similar estimates demonstrated for the 2 procedures: THA, 0.65 (95% CI, 0.59 to 0.70) and TKA, 0.57 (95% CI, 0.50 to 0.64). Of note, heritability decreased with higher BMI in both men and women for THA and in men for TKA. But in women, heritability for TKA increased with higher BMI (0.37 for a BMI of 20 kg/m2 and 0.87 for a BMI of 35 kg/m2).
Although the need for THA or TKA is not a perfect indicator of osteoarthritis (plenty of osteoarthritis does not become symptomatic enough to warrant total joint arthroplasty), this large study offers further data on the question of genetic susceptibility to the development of osteoarthritis. Understanding the influence of obesity (a modifiable risk factor) becomes increasingly important and warrants continued investigation in studies exploring heritability in relation to orthopaedic conditions.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
I was once told that if you don’t have any cases with complications, you either aren’t operating enough or aren’t following your patients. Although we in the orthopaedic community make every effort to minimize the occurrence of patient complications, one that remains difficult to eradicate is periprosthetic joint infection (PJI), which is a leading cause of revision total knee arthroplasty (TKA). The welfare of our patients requires successfully addressing this potentially devastating outcome, but reimbursement for these complex cases has decreased over the past decade.
In the upcoming issue of JBJS, Jella et al. offer insight on temporal trends in Medicare physician reimbursement for revision TKA. They queried the Medicare Physician Fee Schedule Look-Up Tool for pricing information corresponding to 1 and 2-stage revision TKAs and used monetary data from Medicare Administrative Contractors to calculate nationally representative means. The authors evaluated aseptic revision of 1 component, 1-stage revision (aseptic or septic), and both the first and second stages of a 2-stage septic revision.
They found that, from 2002 to 2019, there was a mild increase in the physician fee for each CPT code, with the exception of that for second-stage implantation. However, after adjusting for inflation, total Medicare reimbursements declined for both septic and aseptic revision TKAs (between 23% and 33%), with a significantly greater decline observed for septic revision.
The authors also found that Medicare spending on aseptic revision TKA nearly doubled from 2004 to 2017, while spending on septic revision TKA increased only slightly. They note that a main driver of the discrepancy between septic and aseptic revision may be the reimbursement for the second stage of the former procedure using CPT 27447 instead of a revision procedure code (27487).
We know that an increase in revision TKAs (both septic and aseptic) is expected as the number of primary TKA procedures continues to rise. If reimbursement doesn’t keep pace, it is likely to drive certain surgeons away from tackling the sometimes difficult cases, in turn, leaving our patients with fewer available resources when faced with PJI.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
In the past decade, we’ve learned through a multitude of studies that patient factors can have a substantial impact on the outcomes of orthopaedic interventions. Medical comorbidities, body habitus, and level of fitness are just a few factors we have evaluated. We also now better understand the impact of socioeconomic status and education level on access to care and the results of that care. And importantly, contemporary research is giving us a more complete picture of the relationship between a patient’s mental status and functional outcomes.
Geng et al. provide further insight into this relationship in a recent JBJS report. In a randomized controlled trial conducted at their institution in the People’s Republic of China, the authors investigated whether psychological intervention for patients with depression improved outcomes of total knee arthroplasty (TKA). Among 600 patients prospectively screened, 53 were identified with depressive disorders; 49 remained in the final analysis (24 randomized to standard TKA care and 25 randomized to perioperative psychotherapeutic interventions administered by a mental health professional). Those in the intervention group not only had a significantly higher rate of satisfaction compared with the control group, but they also showed greater improvements in functional outcome scores, range of motion, and scores on depression scales.
As Pablo Castañeda, MD emphasizes in a related Commentary on this article, “Total knee replacement cannot be seen as an isolated intervention without considering the many other factors that contribute to outcomes.” I know that mental health concerns—especially depression—can be difficult to identify during all-too-brief orthopaedic consultations with patients. But they will reap important benefits if we learn to better recognize depression, engage patients in conversations related to mental health, and team with our mental health colleagues for referrals and support. The study by Geng et al. points to a model of care with potential for wider adoption. Considering our community of highly motivated orthopaedic surgeons who are dedicated to the holistic welfare of patients, I believe it is possible to raise our skills in this area close to the level of our ability to examine a knee radiograph.
Marc Swiontkowski, MD
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.
Corticosteroids are commonly used in total knee arthroplasty (TKA) to reduce pain and prevent nausea. But are the effects of steroids different when administered locally rather than systemically? Hatayama et al. investigate this question in JBJS, where they report on a randomized controlled trial comparing periarticular injection with intravenous (IV) administration of corticosteroids. The authors assessed the drugs’ effects on pain control, the prevention of postoperative nausea, and inflammation and thromboembolism markers following TKA.
The 100 included patients were 50 to 85 years of age and underwent primary, unilateral TKA for osteoarthritis. Fifty patients were randomized to the intravenous group (10 mg dexamethasone IV 1 hour pre- and 24 hours postoperatively, along with periarticular placebo injection during the procedure), and 50 were randomized to the periarticular injection group (a 40-mg injection of triamcinolone acetonide during surgery, along with IV placebo 1 hour pre- and 24 hours postoperatively).
Patients in the periarticular injection group experienced better pain control at 24 hours postoperatively, both at rest and during walking. The antiemetic effect was similar and notable in both groups. The IV group showed a better anti-thromboembolic effect, as measured by prothrombin fragment 1.2 levels, but the incidence of deep venous thrombosis was low overall, each group having only 2 cases.
The authors also reported that, at 24 and 48 hours, interleukin-6 levels did not differ between the groups, while C-reactive protein (CRP) levels were significantly lower in the IV group. In contrast, 1 week after surgery, patients in the periarticular group had a significantly lower CRP. These inflammatory-marker findings lead Hatayama et al. to postulate that “the better [24-hour] pain control in the periarticular injection group was not because of reduced inflammation,” and they note that locally administered corticosteroids directly inhibit signal transmission in nociceptive fibers.
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.
It’s hard to contemplate “conservative treatment” in the case of a revised total knee arthroplasty (rTKA) with extensive instrumentation that needs a reoperation due to periprosthetic joint infection (PJI), because all the treatment options in that scenario are pretty complex. In the January 6, 2021 issue of JBJS, Barry et al. report on a retrospective review of 87 revisions of extensively instrumented rTKAs that found that irrigation and debridement (I&D) with chronic antibiotic suppression was as effective as 2-stage exchange in preventing another reoperation for infection—and more effective in terms of maintaining knee function.
The average follow-up of the cases studied was 3.2 years, and the authors carefully defined “extensive instrumentation.” Among the 56 patients who were managed with I&D and suppression and the 31 who were managed with the initiation of 2-stage exchange (average age in both groups approximately 67 years), no significant differences were found in the rates of reoperation for infection or mortality. However, 9 of the 31 patients (29%) in the 2-stage group never underwent the second-stage reimplantation. Among those 9, 3 died prior to reimplantation and 2 underwent amputation due to failure of infection control.
Moreover, at the time of the latest follow-up, a significantly higher percentage of patients in the I&D group were ambulatory (76.8% vs 54.8% in the 2-stage group) and were able to functionally bend their knee (85.7% vs 45.2% in the 2-stage group). The authors surmise that these 2 findings are related to the soft-tissue damage and bone loss that typically occur during stage-1 removal of rTKA components.
Barry et al. conclude that in similar situations “deviating from the so-called gold standard of 2-stage exchange and accepting the modest results of I&D may be in the best interest of the patient,” as long as there are no loose implants in the existing construct. But the “sobering” mortality rates in the study (39.3% in the I&D group and 38.7% in the 2-stage group) remind us that this clinical scenario is extremely challenging for patients and surgeons, no matter which option is selected.
Click here to view an “Author Insights” video about this study with co-author Jeffrey Barry, MD.
The clinical and functional outcomes after total knee arthroplasty (TKA) are generally very favorable. The 15% to 20% of subpar patient-reported outcomes are usually related to persistent pain. Orthopaedic researchers have exhaustively investigated patient factors and technical considerations to address dissatisfaction in this minority population of TKA patients.
Meanwhile, the orthopaedic community has focused on prosthetic design in its attempts to incrementally improve outcomes for the 80% to 85% of generally satisfied TKA patients. Clearly documenting those incremental improvements often requires elegant study design. That’s what we see in the January 6, 2021 issue of The Journal, where Kim et al. report findings from a randomized trial in which 2 different knee-implant designs were compared in the same patients after primary simultaneous bilateral TKA.
Each of the 50 patients (49 of them women) received a posterior-stabilized design in 1 knee and an ultracongruent prosthesis in the other. Kim et al. selected the Forgotten Joint Score (FJS) as the primary outcome. The FJS is a 12-item questionnaire that assesses patient awareness of the artificial joint during daily activities. At 2 years, the researchers found no between-knee differences in FJS. The ultracongruent knees showed more anteroposterior laxity and less femoral rollback than the posterior-stabilized knees, but there were, again, no between-group differences in following measures:
- Range of motion
- Knee Society and WOMAC scores
- Side Preference and patient satisfaction
The ultracongruent advancement in prosthetic design does not appear to offer clinically important advantages over the posterior-stabilized design. But if additional TKA patients can be recruited into studies using clever and effective experimental designs like this one, the future is bright for more robust assessments of the incremental impact of prosthetic design on functional and clinical outcomes.
Click here to view an Infographic summarizing this study.
Marc Swiontkowski, MD
There are many more “types” of diabetes than the pathophysiologic designations of Type 1 and Type 2. In the December 16, 2020 issue of The Journal of Bone & Joint Surgery, Na et al. delineate 4 different diabetes categories and determine their impact on 90-day complications and readmission rates after elective total joint arthroplasty (TJA) among Medicare patients. One premise for this investigation was that, although diabetes is a known risk factor for arthroplasty complications, alternative payment models such as the federally run Comprehensive Care for Joint Replacement (CJR) program adjust their payments only in diabetes cases where the comorbidity is coded as severe.
The authors stratified diabetes into 4 groups as follows:
- No diabetes
- Controlled-uncomplicated diabetes
- Controlled-complicated diabetes
- Uncontrolled diabetes
Among the >500,000 total knee arthroplasties (TKAs) and total hip arthroplasties (THAs) analyzed, the authors found the following when comparing data from the 3 diabetes groups with the no-diabetes group:
- The odds of TKA complications were significantly higher for those with uncontrolled diabetes (odds ratio [OR] = 1.29).
- The odds of THA complications were significantly higher for those with controlled-complicated diabetes (OR = 1.45).
- The odds of readmission were significantly higher in all diabetes groups for both TKA (ORs = 1.21 to 1.48) and THA (ORs = 1.20 to 1.70).
The authors come to 3 basic conclusions based on these findings:
- The odds of hospital readmission and complications following an elective TKA or THA are increased for Medicare beneficiaries who have diabetes.
- It would be reasonable to defer arthroplasty surgery for those with uncontrolled diabetes to allow them to achieve glycemic control.
- The Centers for Medicare & Medicaid Services should include less-severe diabetes and associated systemic complications in alternative-payment model adjustments.
Click here for an “Author Insight” video about this study from co-author Annalisa Na, PhD, DPT.