The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation.

BACKGROUND: Recent advances in high-throughput DNA sequencing technologies have made it possible to characterize the microbial profile in anatomical sites previously assumed to be sterile. We used this approach to explore the microbial composition within joints of osteoarthritic patients. METHODS: This prospective multicenter study recruited 113 patients undergoing hip or knee arthroplasty between 2017 and 2019. Demographics and prior intra-articular injections were noted. Matched synovial fluid, tissue, and swab specimens were obtained and shipped to a centralized laboratory for testing. Following DNA extraction, microbial 16S-rRNA sequencing was performed. RESULTS: Comparisons of paired specimens indicated that each was a comparable measure for microbiological sampling of the joint. Swab specimens were modestly different in bacterial composition from synovial fluid and tissue. The 5 most abundant genera were Escherichia, Cutibacterium, Staphylococcus, Acinetobacter, and Pseudomonas. Although sample size varied, the hospital of origin explained a significant portion (18.5%) of the variance in the microbial composition of the joint, and corticosteroid injection within 6 months before arthroplasty was associated with elevated abundance of several lineages. CONCLUSIONS: The findings revealed that prior intra-articular injection and the operative hospital environment may influence the microbial composition of the joint. Furthermore, the most common species observed in this study were not among the most common in previous skin microbiome studies, suggesting that the microbial profiles detected are not likely explained solely by skin contamination. Further research is needed to determine the relationship between the hospital and a "closed" microbiome environment. These findings contribute to establishing the baseline microbial signal and identifying contributing variables in the osteoarthritic joint, which will be valuable as a comparator in the contexts of infection and long-term arthroplasty success. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

An Enhanced Understanding of Culture-Negative Periprosthetic Joint Infection with Next-Generation Sequencing: A Multicenter Study.

BACKGROUND: The challenges of culture-negative periprosthetic joint infection (PJI) have led to the emergence of molecular methods of pathogen identification, including next-generation sequencing (NGS). While its increased sensitivity compared with traditional culture techniques is well documented, it is not fully known which organisms could be expected to be detected with use of NGS. The aim of this study was to describe the NGS profile of culture-negative PJI. METHODS: Patients undergoing revision hip or knee arthroplasty from June 2016 to August 2020 at 14 institutions were prospectively recruited. Patients meeting International Consensus Meeting (ICM) criteria for PJI were included in this study. Intraoperative samples were obtained and concurrently sent for both routine culture and NGS. Patients for whom NGS was positive and standard culture was negative were included in our analysis. RESULTS: The overall cohort included 301 patients who met the ICM criteria for PJI. Of these patients, 85 (28.2%) were culture-negative. A pathogen could be identified by NGS in 56 (65.9%) of these culture-negative patients. Seventeen species were identified as common based on a study-wide incidence threshold of 5%. NGS revealed a polymicrobial infection in 91.1% of culture-negative PJI cases, with the set of common species contributing to 82.4% of polymicrobial profiles. Escherichia coli, Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus ranked highest in terms of incidence and study-wide mean relative abundance and were most frequently the dominant organism when occurring in polymicrobial infections. CONCLUSIONS: NGS provides a more comprehensive picture of the microbial profile of infection that is often missed by traditional culture. Examining the profile of PJI in a multicenter cohort using NGS, this study demonstrated that approximately two-thirds of culture-negative PJIs had identifiable opportunistically pathogenic organisms, and furthermore, the majority of infections were polymicrobial. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

A Postmortem Analysis of Polyethylene Damage and Periprosthetic Tissue in Rotating Platform and Fixed Bearing Tibial Inserts.

BACKGROUND: Mobile bearing designs are intended to reduce wear, but mixed results were reported from retrieval analyses. Postmortem evaluation (PM) provides the opportunity to assess polyethylene damage in successful implants. We compared damage patterns, MRI presentation, and histology between mobile-bearing and fixed tibial inserts retrieved postmortem and compared these results to our prior findings from implants retrieved at revision. METHODS: Eleven postmortem knees with rotating platform (RP) implants and 13 with fixed bearing (FB) implants were examined. All were MRI scanned, and tissue samples were collected from standardized regions for histology. Polyethylene inserts were subjectively scored to assess articular, backside, and PS post surfaces for damage modes and severity. RESULTS: Average duration of implantation was 9.3 years (1.7-19.6 years). Surface burnishing was the most common polyethylene damage mode. Average damage scores were higher for RP (53.4) compared to FB inserts (34.4) due to greater backside damage (13.4 for RP vs 1.4 for FB). A minimal difference in damage was observed on the articular surfaces (37.4 RP vs 30.0 FB). Mild innate macrophage reactions were seen in 8 (72.7%) RP and 5 (45.5%) FB specimens. Polyethylene particles were identified in 7 (63.6%) RP and 3 (27.7%) FB specimens. CONCLUSIONS: Postmortem inserts showed low damage levels and mild tissue reactions compared to those reported for implants removed at revision arthroplasty. Nonetheless, trends in comparing RP and FB inserts were consistent with those seen in retrieval analyses, demonstrating the usefulness of retrieval studies in capturing performance differences among TKA designs.

Direct Anterior Approach for Primary Total Hip Arthroplasty Lowers the Risk of Dislocation Compared to the Posterior Approach: A Single Institution Experience.

BACKGROUND: One purported benefit of the direct anterior approach (DAA) for total hip arthroplasty (THA) is a lower rate of postoperative dislocation. METHODS: An institutional database was used to identify 8840 primary THAs performed from 2003 to 2020 including 5065 (57%) performed using the DAA and 3775 (43%) performed via the posterior approach (PA). Direction and mechanism of dislocation were determined from chart review. Outcomes were compared using Kaplan-Meier survivorship with dislocation as the endpoint and a Cox multivariate regression was used to investigate factors associated with dislocation. The mean follow-up was 1.7 ± 2.0 years for the DAA and 3.1 ± 3.3 years for the PA. RESULTS: The 0.5% (26/5065) incidence of dislocation among DAA hips was significantly less than the 3.3% (126/3775) among PA cases (P < .001). The majority of dislocations were posterior (DAA 57%, PA 79%) and occurred during activities of daily living (DAA 82%, PA 77%). Five-year survivorship was significantly higher for the DAA group compared to the PA group (99.1% vs 95.4%, P < .001). Dislocation risk was 4.9 times higher for the PA compared to the DAA (hazard ratio = 4.9, 95% confidence interval = 3.2-7.5, P < .001). Increasing head diameter reduced the risk (hazard ratio = 0.70, 95% confidence interval = 0.57-0.86, P < .001). The 0.2% incidence (10/5065) of revision for instability among the DAA group was significantly lower than the 1.1% (43/3775) rate for the PA group (P < .001). CONCLUSION: Compared to primary THAs performed with the PA, DAA cases had a lower risk of dislocation, higher survivorship with dislocation as an endpoint, and a lower risk of revision for instability in this single institution cohort.

The Effect of Intraoperative Radiographs on Component Position and Leg Length during Routine Posterior Approach Total Hip Arthroplasty.

PURPOSE: Accurate component placement and restoration of patient anatomy are critical in total hip arthroplasty (THA) surgery. Although intraoperative radiographs are sometimes utilized, it is unclear whether this practice can improve accuracy. MATERIALS AND METHODS: This study evaluated acetabular cup abduction, anteversion, leg length, and offset among 100 posterior approach THAs performed without imaging (No X-ray group) and compared them to a subsequent series of 100 THAs where an intraoperative radiograph was taken with the trial components in place (X-ray group). THAs were performed using a posterior approach by a single, experienced surgeon whose goal was to place the cup at 45° of abduction and 30° of anteversion. Supine anteroposterior pelvic digital radiographs taken at the first (nominal 4-week) postoperative visit were used for measurements. RESULTS: Slight differences in cup abduction (47°±6° vs 44°±6°, respectively, P=0.003) and anteversion angle (35°±6° vs 31°±6°, respectively, P<0.001) were observed between the X-ray and No X-ray groups; however, a similar proportion of cups within 10° of the target angles was observed (76% vs 83%, respectively, P=0.22). No difference in offset measurements (1.1±6.6 mm vs 0.3±6.9 mm, respectively, P=0.42) or leg lengths (0.3±3.8 mm vs 0.3±4.8 mm, respectively, P=0.94) was observed between the X-ray and No X-ray groups; however, the X-ray group showed less leg length variation (P=0.05). CONCLUSION: In this study, the routine use of intraoperative radiographs was not associated with improved implant positioning for uncomplicated primary THA.

Custom Triflange Cups: 20-Year Experience.

BACKGROUND: The custom triflange acetabular component is used during revision THA to address severe acetabular bone loss. Midterm results are promising, with low rates of loosening and triflange revision reported. However, reoperation and overall complication rates remain high. We aim to investigate our institution's custom triflange experience over 20 years by evaluating implant survivorship, reoperations, complications, and clinical outcomes. METHODS: Prospectively collected data were reviewed for 50 patients undergoing revision THA with the use of a triflanged component from January 2000 to December 2018. 94% among these cases had a known outcome or minimum two year follow-up. Outcomes related to the triflange component were recorded, including revisions, reoperations, surgical complications, medical complications, Harris hip scores, and patient satisfaction. Phone interviews were conducted with patients whose recent follow-up exceeded 2 years. Radiographic review was performed to define implants as either stable or unstable. RESULTS: The average Harris hip scores improved 24 points (49 to 73; P < .001). 91% of eligible patients were satisfied at follow-up. One patient was scheduled for revision at an outside institution during the study period. There were 2 reoperations (1 acute infection and 1 screw removal). One patient died due to pulmonary thromboembolism. A Trendelenberg gait was present in 46% (23/50) of patients. There were 14 major complications (28%). Dislocation (12%) was the most common complication. CONCLUSION: Custom triflange components provide a reliable solution for managing complex acetabular defects in revision THA. Patients should be counseled on magnitude of surgery and the high incidence of complications, specifically infection and dislocation.

Periprosthetic Femur Fracture Risk: Influenced by Stem Choice, Not Surgical Approach.

BACKGROUND: Periprosthetic femur fracture (PFF) remains a common reason for failure after total hip arthroplasty (THA). For over 10 years, our institution has performed both anterior approach (AA) and posterolateral (PL) approaches for primary THA with multiple stem designs. The aim of this study is to determine the 90-day relative risk of PFF with regard to approach and stem design. METHODS: A retrospective review of our institutional database was performed on all patients undergoing primary THA from 2007 to 2018 using AA or PL approaches. Five surgeons performing 6309 THAs (AA = 4510; PL = 1799) using single-wedge taper (n = 2417) or fit-and-fill (n = 3892) stems were included. PFF occurring within 90 days of the index procedure were analyzed. Differences in PFF rates, fracture location, stem type, and treatment method were assessed. Comparisons were made using a Cox regression analysis. RESULTS: The 90-day revision rate for fracture was 0.3%. Clinically significant fractures requiring cerclage cabling, stem change, revision, or open reduction internal fixation occurred in 0.9% of patients (intraoperative = 37, 0.6%; postoperative = 17, 0.3%). Cox regression found PFF risk was significant for female patients (P = .008), patients older than age 65 (P < .01), single-wedge taper stems (P = .05), and for cases with collarless stems (P = .04). Among PFF cases that required surgical intervention, risk factors were female sex, age older than 65, and body mass index under 25 (P < .05). Collarless stems were 2.6 times more likely to result in PFF than collared stems (P = .04). Single-wedge taper stems were 2.3 times more likely to result in PFF than fit-and-fill stems (P = .05). Approach was not found to be an independent risk factor for PFF (P = .85). CONCLUSION: Our single-center experience demonstrates the risk of periprosthetic fracture within 90 days of surgery is significantly lower with collared stems and fit-and-fill stem designs. Female sex, age over 65, and body mass index below 25 nearly double the PFF risk. Surgical approach did not influence fracture rates.

Narcotic Consumption in Opioid-Naïve Patients Undergoing Total Hip and Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is associated with increased risk of prolonged narcotic requirement compared to total hip arthroplasty (THA). This study aims to compare acute postoperative narcotic consumption between the 2 procedures and quantify amount of narcotics used by opioid prescribed. METHODS: From October 2017 to August 2019, patients were surveyed at 4-week follow-up to determine amount and duration of opioids used and whether they continued to require narcotics. Among 1332 patients who self-identified as opioid naïve, 670 underwent THA and 662 underwent TKA. Descriptive analysis was performed based on data type. RESULTS: The total morphine equivalent dose (MED) used in the postoperative period was lower in THA than in TKA (143 ± 160 vs 259 ± 250 MED, P < .001). The duration of use was shorter, total amount of pills consumed was lower, and refill rates were less in THA compared to TKA regardless of which opioid was prescribed. A smaller proportion of patients required narcotics at 4-week follow-up in THA compared to TKA. A postoperative prescription of 45 pills of any one type of narcotic was sufficient for nearly 90% of THA patients, and 60 pills of any one type of narcotic was appropriate for over 75% of TKA patients. CONCLUSION: THA is associated with less total narcotic consumption, shorter duration of use, less refills, and lower likelihood of requiring narcotics at 4-week follow-up. Percentiles of total narcotics consumed are provided to promote judicious postoperative prescribing patterns, and one could consider further reducing narcotics when utilizing our protocol, particularly for THA patients. LEVEL OF EVIDENCE: This is a level III retrospective cohort study reviewing narcotic use in over 900 consecutive opioid-naïve patients undergoing total hip and knee arthroplasty.

Narcotic Consumption in Opioid Naïve Patients Undergoing Unicompartmental and Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is associated with increased risk of prolonged narcotic requirement compared to unicompartmental knee arthroplasty (UKA). The purpose of the current study is to compare acute postoperative narcotic consumption between the 2 procedures and quantify narcotic consumption. METHODS: From October 2017 to August 2019 patients were surveyed for four weeks to determine the amount and duration of opioids consumed and requirement for continued narcotics. Among 976 opioid naïve patients, 314 (32%) underwent UKA and 662 (68%) underwent TKA. Patients were analyzed according to specific narcotic prescribed. Total morphine equivalent dose (MED), number of pills, duration, refill percentage, and usage percentage for 4 weeks were calculated for each procedure. RESULTS: MED used in the postoperative period was lower in patients undergoing UKA than TKA (200 ± 195 vs 259 ± 250 MED, P = .002). Total number of pills consumed and duration of use was less in UKA compared to TKA regardless of which opioid was prescribed. A smaller proportion of patients required narcotics for 4 weeks after UKA (32% vs 43%, P < .001), and fewer UKA patients required narcotic refills (14% vs 27%, P < .001). Sixty pills of any 1 type of narcotic was sufficient for 90% of UKA patients and over 75% of TKA patients. CONCLUSION: UKA is associated with less narcotic consumption, shorter duration of use, less refills, and lower likelihood of narcotic requirement for 4 weeks. We report narcotic consumption patterns for both procedures to aid surgeons in judicious postoperative prescribing. LEVEL OF EVIDENCE: This is a level III retrospective cohort study reviewing narcotic use in over 900 consecutive opioid naïve patients undergoing UKA or TKA.

Outpatient Total Hip Arthroplasty Performed at an Ambulatory Surgery Center vs Hospital Outpatient Setting: Complications, Revisions, and Readmissions.

BACKGROUND: Outpatient total hip arthroplasty (THA) utilization continues to grow. Literature suggests outpatient THA may result in low rates of complications and readmission. There are no studies comparing safety profiles of THA performed at ambulatory surgery centers (ASC) vs hospital outpatient (HOP) settings. METHODS: Prospectively collected data were reviewed on all patients who underwent THA from 2013 to 2018. ASC and HOP subgroups were compared, investigating difference in demographics, comorbidities, American Society of Anesthesiologists subgroups, all complications, revisions, emergency department (ED) visits, and readmissions within the first 90 days of surgery. An additional subgroup analysis of patients younger than 65 years was performed. RESULTS: Two surgeons performed 3063 THAs during the study period, including 965 outpatient cases (ASC = 335; HOP = 630). Thirty-seven (3.8%) complications occurred within 90 days. No differences were found between groups for 90-day complication rates (ASC = 13, 3.9%; HOP = 24, 3.8%; P = .48), revision rates (ASC = 0, 0%; HOP = 2, .3%; P = .30), all-cause reoperation rates (ASC = 1, 0.3%; HOP = 5, 0.8%; P = .35), ED visits (ASC = 3, 0.9%; HOP = 2, 0.3%; P = .23), or readmission rates (ASC = 2, 0.6%; HOP = 9, 1.4%; P = .25). CONCLUSION: THA can be safely performed in both ASC and HOP settings with low 90-day postoperative complication, revision, reoperation, ED visit, and readmission rates. Based on the populations studied, we identified no statistically significant differences in rates of complications between ASC and HOP groups.

A Prospective, Randomized Study of Surgical Positioning Software Shows Improved Cup Placement in Total Hip Arthroplasty.

Several technologies are available to assist surgeons with acetabular component positioning in total hip arthroplasty. The purpose of this study was to determine whether surgical positioning software would improve cup position compared with fluoroscopy. This prospective, randomized study compared 200 primary total hip arthroplasty cups placed with and without surgical positioning software. All cases were performed by a single surgeon using the direct anterior approach with fluoroscopy. The target abduction and anteversion angles were set at 40° and 20°, respectively, and measured postoperatively. Cup placement time, total fluoroscopy time, and cup position were compared between groups. Mean abduction was 40.4° (range, 32.7°-49.0°) in the software group compared with 42.3° (range, 33.7°-51.1°) in the control group. The cups placed using software were significantly closer to the target abduction angle (P<.001) with fewer outliers. Mean anteversion was 20.8° (range, 11.2°-31.7°) in the software group compared with 21.8° (range, 11.3°-34.3°) in the control group (P=.063). Eighty-seven percent of cups in the software group fell within 5° of the abduction target, compared with only 68% in the control group (P<.01). Cup placement took longer in the software group (7:04 minutes vs 4:58 minutes, P<.001), and 2 seconds more total fluoroscopy time was used in that group as well (12.9 seconds vs 11.1 seconds, P<.001). The software improved both the accuracy and the precision of cup placement, with only modest increases in surgical time and fluoroscopy time. [Orthopedics. 2019; 42(1):42-47.].

The Lawrence D. Dorr Surgical Techniques & Technologies Award: "Running Two Rooms" Does Not Compromise Outcomes or Patient Safety in Joint Arthroplasty.

BACKGROUND: Scrutiny from the federal government and the media regarding the safety of 1 surgeon doing cases in 2 operating rooms (ORs) on the same day, prompted us to examine our own institutional data. Over the past 11 years, surgeons at our facility have operated consecutively in 1 OR on a given day or used 2 alternating ORs. This study compares these cases with a focus on revisions and complications in both groups. METHODS: Six surgeons performed a total of 16,916 primary hip and knee arthroplasties from 2006-2016. 7002 cases (41%) were consecutive cases (CCs) and 9914 cases (59%) were overlapping cases (OCs). Intraoperative complications, component revisions, and postoperative complications within 90 days of surgery were compared between the CC and OC groups. RESULTS: There was no difference in intraoperative complication rates between the two groups (CC 1.6% vs. OC 1.7%, relative risk 1.082, 95% confidence interval 0.852 to 1.375, P = .52). There was no difference in 90-day component revision rates among the CC and OC groups (0.66% vs. 0.85% respectively, relative risk = 1.290, 95% confidence interval 0.901 to 1.845, P = .19). There was also no difference in 90-day complication rates among the CC and OC groups (1.33% vs. 1.45% respectively, relative risk = 1.094, 95% confidence interval 0.844 to 1.417, P = .54). CONCLUSION: This large study of a single institution with multiple surgeons over an 11-year period shows no compromise in patient safety or outcomes when comparing cases done in either consecutive or overlapping rooms.