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.
Total hip arthroplasty (THA) with ceramic-on-ceramic (CoC) bearings has become popular, especially in younger patients, largely because of the material’s durability. However, CoC bearings are susceptible to catastrophic failure through fracture. Although the definitive mechanistic pathway for ceramic fracture has not been elucidated, one of the proposed mechanisms is impingement between the ceramic acetabular liner and the metal neck of the femoral stem. In the January 20, 2021 issue of The Journal, Lee et al. take an illuminating radiographic dive into the patterns of impingement in CoC THA.
The authors analyzed 244 cases of CoC THAs that had ≥15 years of radiographic follow-up. They found impingement-related notches at 77 sites in 57 (23.4%) of the cases. The notches were seen either on the neck (28 cases) or on the shoulder (29 cases) of the stem. In 8 cases, notches were found in multiple locations.
All of the neck notches were found when either a medium-neck or long-neck head was used. Shoulder notches were found on the stem only when a short-neck head was used. Lee et al. observed that the use of medium-neck or long-neck heads prevents the ceramic liner from contacting the stem shoulder because the liner impinges on the neck first. The authors also noted that the mean cup inclination was significantly lower in the cases with notched stems compared to stems without notches (36.9° vs 39.8°), and that mean anteversion was higher in the cases with notches (19.9° vs 17.3°).
We have known that impingement can occur between the ceramic liner and metal stem in CoC THA, but this study suggests that it may happen in a significant proportion of patients, both along the neck and shoulder of the stem. Manufacturers should consider these findings when designing implants, and patients and surgeons considering CoC implants may want to avoid short-neck heads, if possible. Also, because impingement-related stem notching appears to occur more frequently with lower cup inclination and higher anteversion, surgical technique remains vitally important in these cases, independent of implant design and selection.
Finally, we should note that the patients in this study were young (mean age of 43 years) and Asian. Asian culture and lifestyle include frequent squatting and sitting cross-legged, which Lee et al. say “induces more impingement between the stem and liner.”
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Total hip arthroplasty (THA) is a tried-and-true treatment for debilitating hip osteoarthritis. But as the number of patients undergoing THA continues to rise, so does the incidence of periprosthetic femoral fractures and the need for revision surgery. The increasing burden of periprosthetic fractures has led to the development of shorter-stemmed femoral components that theoretically preserve bone, decrease fracture risk, and make revision surgery easier if it is required. In the January 6, 2021 issue of The Journal, Slullitel et al. report on a randomized controlled trial that determined whether bone loss differed between patients who received a conventional stem and those who received a short, bone-preserving stem over 2 years following THA.
Forty-six patients received the short, proximally porous-coated stem (Depuy Synthes Tri-Lock bone-preservation stem), and 40 received the conventional stem (Depuy Synthes collarless Corail stem). The primary outcome–bone mineral density (BMD)–was analyzed at 12, 26, 52, and 104 weeks after surgery with dual x-ray absorptiometry region-free analysis (DXA-RFA), which revealed pixel-level resolution of BMD at the bone-implant interface.
Immediately after surgery, researchers found a similar amount of bone loss in both groups in the calcar region and the cancellous portion of the distal greater trochanter. But at all other subsequent time points, bone loss was significantly greater in patients with the bone-preserving stem (analysis of variance [ANOVA] p < 0.0001). In addition, over the full study period the small areas of bone gain that the researchers found were statistically greater in the conventional-stem group than in the Tri-Lock group. Notably, patient-reported outcomes and adverse events did not differ between the 2 groups at the 2-year follow-up.
These early results cast a shadow of doubt over whether a stem that is marketed to preserve bone actually accomplishes that objective. However, 2 years is a very short follow-up when looking at the lifetime of a hip arthroplasty, and the clinical implications of these findings will become clearer with longer-duration analysis.
Click here to read a JBJS Clinical Summary titled “Short-Stem Femoral Components in THA” by Tad Mabry, MD.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
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.
No consensus has emerged yet regarding the best prosthetic construct with which to manage patients who require revision surgery for dislocation after a total hip arthroplasty (THA). But in the December 2, 2020 issue of The Journal of Bone & Joint Surgery, Hoskins et al. add insight into that question by tapping the Australian Orthopaedic Association Total Joint Replacement Registry to analyze which of 4 first-revision component constructs led to the fewest second revisions.
Among the 1,275 THAs that were revised once for prosthesis dislocation, 203 hips went on to have a second revision, with dislocation being the most common cause for re-revision. The authors studied the second-revision THAs in 4 prosthetic categories: standard-sized femoral heads, large-sized femoral heads, dual-mobility heads, and constrained acetabular liners. The rate of all-cause second revision was significantly higher in the standard-head group when compared with the constrained-liner group. But in the 91 cases of second revisions for dislocation, the standard head showed significantly higher second-revision rates than any of the other 3 constructs. There was no statistically significant difference in rates of second revision between those 3 non-standard articulations
The authors discuss dual-mobility heads at some length, asserting that “caution should be exercised in their routine use, particularly in younger and active patients.” They note that the constrained liner was the “only articulation to show a difference when compared with standard-head THA for both all-cause revision and revision for a subsequent diagnosis of dislocation,” but they observe that impingement and acetabular component loosening are common concerns with constrained liners.
Despite these caveats, it seems clear from this data that the choice of articulating surface for either a first or second revision THA due to dislocation should probably exclude standard head sizes. Calling for longer-term data on all 3 alternative constructs studied here (the follow-up periods were different for all 4 articulations), the authors emphasize that “surgeons should [also] look beyond articulating surfaces”—to surgical approach, component orientation, and patient factors such as soft-tissue quality—in the effort to reduce the burden of THA dislocations.
Remember when a “dashboard” referred to the display just behind a car’s steering wheel? In today’s digital universe, the word has come to mean any number of visual information displays. At the same time, the meaning of the word “value” has narrowed somewhat. In relation to health care, “value” is defined quite precisely as the quality of patient outcomes per dollar spent on healthcare services.
In the November 4, 2020 issue of The Journal of Bone & Joint Surgery, Reilly et al. explain how they created a “value dashboard” for total hip and knee arthroplasty (THA and TKA) at a tertiary-care medical center in New England. The goal: track and display the surgeon-level cost and quality of these procedures against institutional benchmarks to identify opportunities for improving value.
The 7 quality metrics that Reilly et al. used included both clinical and patient-reported outcomes, weighted by surgeons using a modified Delphi process. Average direct costs per surgeon were calculated from the medical center’s billing system, and data were collected over a 15-month period from 2017 to 2018 to ensure at least 1 year of outcomes. Six surgeons were included in the TKA value dashboard, and 5 were included in the THA dashboard.
Relative to the institutional benchmarks:
- Value for TKA by surgeon ranged from 7% below benchmark to 12% above.
- Value for THA by surgeon ranged from 12% below benchmark to 7% above.
The dashboard itself (see Figure above) displays quality, cost, and overall value so viewers can see at a glance which metrics are driving the value score for each surgeon, whose procedural volume is also depicted. The authors cite as one limitation of this study the fact that the quality metrics were weighted by local surgeons only, and they say that “ideally the weighting would be informed by a panel of national experts and several stakeholder groups,… including patients.”
The cost of medical care in the United States has been shown to rise with advancing patient age, and total joint arthroplasty (TJA) is a prime example of this unsurprising phenomenon. In attempts to curtail costs and reduce variability, Medicare and other payers have introduced alternative payment models (APMs), such as the Bundled Payments for Care Improvement (BPCI) initiative. In this model’s application to TJA, when participating institutions keep the cost of the “episode” below a risk-adjusted target price, they accrue the savings as a profit, but they sustain a financial penalty if the episode costs more than the target price.
Multiple studies have suggested that APMs can negatively affect the fiscal health of institutions that care for many high-risk patients. Although increasing age has been associated with higher-cost episodes of care, age is not one of the factors that the BPCI model accounts for. Consequently, concerns have been raised that providers may practice “cost discrimination” against very old patients.
In the October 7, 2020 issue of The Journal, Petersen et al. examine how an aging population has affected a New York City orthopaedic center in terms of the BPCI model applied to TJA. The authors analyzed the relationship between patient age and cost of care among 1,662 patients who underwent primary total hip and knee arthroplasty over a 3-year period under BPCI. They then used a modeling tool to predict shifting age demographics for their local area out to the year 2040.
Petersen et al. found that under BPCI, their institution sustained a nearly $2,000-per-case loss for TJA care episodes among patients 85 to 99 years of age. Currently this loss is offset by profits realized by performing TJAs in younger patients. However, predictive modeling identified an inflection point of 2030, after which a relative increase in older patients and a decrease in younger patients will yield an overall net decrease in profits for primary TJA.
Because no one, including orthopaedic surgeons, can turn back the clock on aging, health care stakeholders must find ways either to adjust downward the cost of care for the elderly (seemingly difficult without adversely affecting outcomes) or adjust reimbursement models to account for the increased costs associated with aging. I agree with the conclusion of Petersen et al.: “The BPCI initiative and [other] novel APMs should consider age as a modifier for reimbursement to incentivize care for the more vulnerable and costly age groups in the future.”
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Every month, JBJS reviews 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 OrthoBuzz specialty-update summaries.
This month, Mengnai Li, MD, PhD, co-author of the September 16, 2020 “What’s New in Hip Replacement,” selected the five most clinically compelling findings from among the 95 noteworthy studies summarized in the article.
Medical Comorbidities and Outcomes of Joint Arthroplasty
–Among 543 malnourished joint arthroplasty patients (with albumin levels <3.4 g/L), an intervention encouraging a high-protein, anti-inflammatory diet shortened the length of hospital stay and lowered readmissions, relative to malnourished arthroplasty patients who did not receive the intervention.1
Surgical Factors and Outcomes of Total Hip Arthroplasty (THA)
–A multicenter, prospective study used propensity-score matching to compare THA performed with a direct anterior approach with THA performed with a posterolateral approach. Researchers found no patient-reported outcome differences at 1.5 months postoperatively or at ≥1 year up to 5 years.2
Periprosthetic Joint Infection (PJI)
–A Musculoskeletal Infection Society workgroup published a recommendation for a 4-tier tool for reporting outcomes after surgical treatment of PJI. Proposed outcomes include infection control with no antibiotic treatment, infection control with suppressive antibiotic therapy, need for reoperation and/or revision and/or spacer retention, and death.
–A meta-analysis found only low-quality retrospective evidence supporting the practice of routinely applying intrawound vancomycin to reduce the rates of PJI. Authors called for a prospective randomized trial before adoption of this practice.3
Postoperative Urinary Retention
–A randomized controlled trial found that preoperative and perioperative administration of tamsulosin did not reduce the incidence of postoperative urinary retention after hip and knee arthroplasty. However, the study included a general male population rather than a higher-risk group.4
- Schroer WC, LeMarr AR, Mills K, Childress AL, Morton DJ, Reedy ME. 2019 Chitranjan S. Ranawat Award: elective joint arthroplasty outcomes improve in malnourished patients with nutritional intervention: a prospective population analysis demonstrates a modifiable risk factor. Bone Joint J.2019 Jul;101-B(7_Supple_C):17-21.
- Sauder N, Vestergaard V, Siddiqui S, Galea VP, Bragdon CR, Malchau H, Elsharkawy KA, Huddleston JI 3rd, Emerson RH. The AAHKS Clinical Research Award: no evidence for superior patient-reported outcome scores after total hip arthroplasty with the direct anterior approach at 1.5 months postoperatively, and through a 5-year follow-up. J Arthroplasty.2020 Feb 12.
- Heckmann ND, Mayfield CK, Culvern CN, Oakes DA, Lieberman JR, Della Valle CJ. Systematic review and meta-analysis of intrawound vancomycin in total hip and total knee arthroplasty: a call for a prospective randomized trial. J Arthroplasty.2019 Aug;34(8):1815-22. Epub 2019 Apr 1.
- Schubert MF, Thomas JR, Gagnier JJ, McCarthy CM, Lee JJ, Urquhart AG, Pour AE. The AAHKS Clinical Research Award: prophylactic tamsulosin does not reduce the risk of urinary retention following lower extremity arthroplasty: a double-blinded randomized controlled trial. J Arthroplasty.2019 Jul;34(7S):S17-23. Epub 2019 Mar 20.
There is a wry saying in academic medicine that “nothing ruins good results like long-term follow-up.” But long-term follow-up helps us truly understand how our orthopaedic interventions affect patients. This is especially important with procedures on children, and the orthopaedic surgeons at the University of Iowa have been masterful with long-term outcome analysis in pediatric orthopaedics. They demonstrate that again in the August 5, 2020 issue of The Journal, as Scott et al. present their results comparing outcomes among 2 cohorts of patients who underwent treatment for developmental hip dislocations between the ages of 18 months and 5 years—and who were followed for a minimum of 40 years.
Seventy-eight hips in 58 patients underwent open reduction with Salter innominate osteotomy, and 58 hips in 45 patients were treated with closed reduction. At 48 years after reduction, 29 (50%) of the hips in the closed reduction cohort had undergone total hip arthroplasty (THA), compared to 24 (31%) of hips in the open reduction + osteotomy group. This rate of progression to THA nearly doubled compared to previously reported results at 40 years of follow-up, when 29% of hips in the closed reduction group and 14% of hips in the open reduction group had been replaced.
In addition, the authors found that patient age at the time of reduction and presence of unilateral or bilateral disease affected outcomes. Patients with bilateral disease who were treated at 18 months of age had a much lower rate of progression to THA when treated with closed reduction, compared to those treated with open reduction—but the opposite was true among patients with bilateral disease treated at 36 months of age. Treatment type and age did not seem to substantially affect hip survival among those with unilateral disease.
I commend the authors for their dedication to analyzing truly long-term follow-up data to help us understand treatment outcomes among late-diagnosed developmental hip dislocations in kids. Long-term follow-up may “ruin” good results, but it gives us more accurate and useful results. And, in this case, the findings reminded us how important it is to diagnose and treat developmental hip dislocations as early in a child’s life as possible.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Acetabular components for primary total hip arthroplasty (THA) made with ultraporous surfaces were developed to enhance osseointegration and biological fixation. In the July 1, 2020 issue of The Journal of Bone & Joint Surgery, Palomaki et al. report on a registry study that suggests that implant survival with these components over an average follow-up of 3.6 years is not so “ultra.”
The authors evaluated >6,000 primary THAs that used a Tritanium ultraporous cup and >25,000 THAs that used a conventional cup, all performed between 2009 and 2017. When they compared the two groups for revision for any reason, the 5-year Kaplan-Meier survivorship of the Tritanium group (94.7%) was inferior to that of the conventional-cup group (96.0%). When revision for aseptic loosening was examined, the 5-year survivorship was also inferior for the Tritanium group (99.0%) compared with the conventional group (99.9%). Regression analysis revealed that the Tritanium group had a much higher risk of revision for aseptic loosening 2 to 4 years after surgery (hazard ratio, 11.2; p <0.001). Interestingly, these survivorship and risk-of-revision differences disappeared when the authors analyzed data for the period from May 15, 2014 to December 31, 2017–when the registry was updated to include patient BMI and ASA-class data.
The authors cite several caveats that readers should apply to these findings. The registry did not capture radiographic findings for these patients, so potentially relevant imaging data could not be analyzed. And, despite the database upgrade in 2014, there was a dearth of available data on patient comorbidities. Finally, wide confidence intervals for some of the hazard-ratio calculations suggest the need to confirm revision-risk findings with further research.
Limitations notwithstanding, the study by Palomaki et al. suggests that the performance of ultraporous cups may not meet the hopes and expectations of hip surgeons and their patients.