Mark Coventry Award: Human Knee Has a Distinct Microbiome: Implications for Periprosthetic Joint Infection.

BACKGROUND: Pathogens causing prosthetic joint infection (PJI) are thought to gain access to the knee during surgery or from a remote site in the body. Recent studies have shown that there is a distinct microbiome in various sites of the body. This prospective study, and first of its kind, was set up to investigate the presence of possible microbiome in human knee and compare the profile in different knee conditions. METHODS: We obtained synovial fluid from 65 knees (55 patients) with various conditions that included normal knee, osteoarthritis (OA), aseptic revision, and those undergoing revision for PJI. The contralateral knee of patients who had a PJI were also aspirated for comparison. A minimum of 3 milliliters of synovial fluid was collected per joint. All samples were aliquoted for culture and next-generation sequencing analysis. RESULTS: The highest number of species was found in native osteoarthritic knees (P ≤ .035). Cutibacterium, Staphylococcus, and Paracoccus species were dominant in native nonosteoarthritic knees, and meanwhile a markedly high abundance of Proteobacteria was observed in the osteoarthritic joints. Moreover, the contralateral and aseptic revision knees showed a similar trend in bacterial composition (P = .75). The sequencing analysis of patients who had PJI diagnosis, confirmed the culture results. CONCLUSION: Distinct knee microbiome profiles can be detected in patients who have OA and other knee conditions. The distinct microbiome in the knee joint and the close host-microbe relationships within the knee joint may play a decisive role in the development of OA and PJI.

The Paradox of Patient-Reported Outcome Measures: Should We Prioritize "Feeling Better" or "Feeling Good" After Total Knee Arthroplasty?

BACKGROUND: The use of preoperative patient-reported outcome measure (PROM) thresholds for patient selection in arthroplasty care has been questioned recently. This study aimed to identify factors affecting achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) after total knee arthroplasty (TKA) and determine the overlap between the two outcomes. METHODS: We identified 1,239 primary, unilateral TKAs performed at a single institution in 2015-2019. PROMs including the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and 12-item Short Form Health Survey (SF-12) were collected preoperatively and 1-year postoperatively. The likelihood of attaining PASS as per attainment of MCID was assessed. A multivariable regression was used to identify predictors of MCID and PASS. RESULTS: In total, 71.3% achieved MCID and 75.5% achieved PASS for KOOS-JR. Only 7.7% achieved MCID but not PASS, whereas almost twice this number did not achieve MCID but did achieve PASS (11.9%). Poorer preoperative KOOS-JR (OR 0.925), better SF-12 physical (OR 1.025), and mental (OR 1.027) were associated with MCID attainment. In contrast, better preoperative KOOS-JR (OR 1.030) and SF-12 mental (OR 1.025) were associated with PASS attainment. Age, gender, race, ethnicity, body mass index, Charlson index, American Society of Anesthesiologists classification, and smoking status were not significant predictors. CONCLUSION: Preoperative PROMs were associated with achieving MCID and PASS after TKA, albeit some positively and some negatively. In the era of value-based care, clinicians should not only strive to help patients "feel better" but also ensure that patients "feel good" after surgery. This study does not support the use of PROMs in prioritizing access to care.

Minimum Five-Year Outcomes of Modular Dual Mobility in Primary Total Hip Arthroplasty.

BACKGROUND: Using a modular dual-mobility (MDM) bearing in primary total hip arthroplasty (THA) has not been widely evaluated. The purpose of this study is to evaluate clinical outcomes and survivorship following MDM bearings in primary THA. METHODS: We used our registry database for patients with an MDM bearing on primary THA, performed by 6 surgeons through supine direct lateral or direct anterior approach. MDM bearings were used most often when impingement or subluxation was present intraoperatively despite proper component position. Another indication was a patient with planned activities who might be at a higher risk of instability postoperatively. RESULTS: A total of 127 MDM bearings were used in primary THA in 119 patients. Mean follow-up was 6.77 years (range 5-8.9). Five hips were revised, none of which were due to MDM bearing failure. Preoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement, Veterans RAND/Short Form 12 Physical Health Score and Mental Health Score increased from 25.81 to 52.40 (P < .0001), 30.42 to 44.50 (P < .0001), and 36.21 to 52.70 (P < .0001) at latest completed survey follow-up, respectively. CONCLUSION: This MDM bearing shows excellent functional outcomes at a minimum 5 years of follow-up with no bearing-related failures. It can be an excellent choice in primary THA specifically in females where the use of increased head size to prevent instability is not possible due to anatomical restrictions and liner thickness.

A Time-Driven Activity-Based Costing Analysis of Simultaneous Versus Staged Bilateral Total Hip Arthroplasty and Total Knee Arthroplasty.

BACKGROUND: Although studies have compared the claims costs of simultaneous and staged bilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA), whether a simultaneous procedure is cost-effective to the facility remains unknown. This study aimed to compare facility costs and perioperative outcomes of simultaneous vs staged bilateral THA and TKA. METHODS: We reviewed a consecutive series of 560 bilateral THA (170 staged and 220 simultaneous) and 777 bilateral TKA (163 staged and 451 simultaneous). Itemized facility costs were calculated using time-driven activity-based costing. Ninety-day outcomes were compared. Margin was standardized to unadjusted Medicare Diagnosis Related Group payments (simultaneous, $18,523; staged, $22,386). Multivariate regression was used to determine the independent association between costs/clinical outcomes and treatment strategy (staged vs simultaneous). RESULTS: Simultaneous bilateral patients had significantly lower personnel, supply, and total facility costs compared with staged patients with no difference in 90-day complications between the groups. Multivariate analyses showed that overall facility costs were $1,210 lower in simultaneous bilateral THA (P < .001) and $704 lower in TKA (P < .001). Despite lower costs, margin for the facility was lower in the simultaneous group ($6,569 vs $9,225 for THA; $6,718 vs $10,067 for TKA; P < .001). CONCLUSION: Simultaneous bilateral TKA and THA had lower facility costs than staged procedures because of savings associated with a single hospitalization. With the increased Medicare reimbursement for 2 unilateral procedures, however, margin was higher for staged procedures. In the era of value-based care, policymakers should not penalize facilities for performing cost-effective simultaneous bilateral arthroplasty in appropriately selected patients.