Faculty Bibliography

INTRODUCTION/BACKGROUND:A two-stage revision has long been the gold standard for chronic periprosthetic joint infections (PJI), with real-component articulating spacers becoming overwhelmingly popular. While several studies have evaluated the success of these spacers in revision total knee arthroplasty (rTKA), to our knowledge, this is the first to specifically compare outcomes of spacers stratified by the level of liner constraint. METHODS:This retrospective analysis reviewed 135 patients who were indicated for two-stage rTKA due to PJI between 2011 and 2023 at a single specialty urban academic institution. Patients were categorized into three groups based on the polyethylene liner constraint used during the first stage: cruciate retaining (CR), posterior stabilized (PS), and varus-valgus constrained (VVC). Of these 135 patients, 60 (44%) were categorized in the CR group, 47 (35%) were in the PS group, and 28 (21%) were in the VVC group. These groups were compared after each stage for peri- and postoperative outcomes such as operative time, length of stay (LOS), discharge disposition, knee range of motion (ROM), as well as incidence of re-revision and reinfection. RESULTS:The mean postoperative LOS was not different among cohorts for both stages. Operative time was significantly longer in the VVC group after the second stage (P = 0.007), while there was no difference after the first stage (P = 0.085). There were no differences in ROM after both stages. The mean ROM after the first stage was 92° in the CR group, 90° in the PS group, and 85° in the VVC group (P = 0.46). After the second stage, ROM was 101° in both the CR and VVC groups and 107° in the PS group (P = 0.28). There were no differences in the risk of re-revision due to re-infection across the groups after the first or second stage procedures. The re-infection incidence after the first stage was 14% in the VVC group, compared to 5% in the CR group and 4% in the PS group (P = 0.14). After the second stage, the reinfection risk was 21% in the VVC group, 8% in the CR group, and 13% in the PS group (P = 0.21). CONCLUSION/CONCLUSIONS:No significant differences were observed in the risk of complications such as re-infection, re-revisions, and postoperative ROM, suggesting that the choice of liner constraint in two-stage revision can be left up to surgeon's discretion.

INTRODUCTION/BACKGROUND:Maintaining follow-up after total joint arthroplasty (TJA) is critical to monitor patient outcomes and complications. However, patient factors associated with follow-up compliance have not been described previously. This study aimed to characterize demographic and perioperative characteristics associated with TJA follow-up compliance. METHODS:This was a retrospective review of all primary, elective total hip and knee arthroplasty (THA and TKA) procedures at an urban, tertiary care center from 2011 to 2022. Patient follow-ups were categorized as early (0 to 90 days), mid-term (91 days to two years), and late-term (greater than two years). Patient characteristics, including age, sex, race, smoking status, spoken language, body mass index, income class, insurance type, distance from hospital, 90-day readmission, American Society of Anesthesia Status, and Charlson Comorbidity Index (CCI), were compared at each period, and logistic regression identified predictors of follow-up. RESULTS:In total, 2,836 TKA and 3,056 THA procedures were analyzed, with overall follow-up rates of 78.9 and 76.8%, respectively. Among all TJA patients, those who did not have follow-up were more likely to be younger, men, White, active smokers, live further from the hospital, and have lower CCIs. Uniquely, for TKA patients, higher income status predicted lower overall and early follow-up rates, while English-speaking predicted lower early and higher late follow-up rates in this subgroup. Differences between groups based on follow-up status decreased as follow-up time increased. Regression analyses showed loss to follow-up increased with increased distance from the hospital and current smoking. Uniquely, for THA, men predicted loss-to-follow-up. CONCLUSION/CONCLUSIONS:Younger age, men, White race, higher income, current smoking, and increased distance from the hospital are associated with increased early, but not late, loss to follow-up after TJA. Future studies should assess the influence of other factors, including home support and telemedicine use, on follow-up rates.

AIMS/UNASSIGNED:The aim of this study was to assess the variations in the positioning of components between sides in patients who underwent staged bilateral total hip arthroplasty (THA), and whether these variations affected patient-reported outcome measures (PROMs). METHODS/UNASSIGNED:A retrospective review included 207 patients who underwent staged bilateral THA between June 2017 and November 2022. Leg length, the height and anteversion of the acetabular component, and the coronal and sagittal angles of the femoral component were assessed radiologically and compared with the contralateral THA. The effect of the surgical approach and the technology used on this variation was also assessed. Linear regression was used to investigate the variations between the two THAs and the PROMs. RESULTS/UNASSIGNED:Between the two sides, the mean leg length varied by 4.6 mm (0.0 to 21.2), the mean height of the acetabular component varied by 3.3 mm (0.0 to 13.7), the mean anteversion varied by 8.2° (0.0° to 28.7°), the mean coronal alignment of the femoral component varied by 1.1° (0.0° to 6.9°), and the mean sagittal alignment varied by 2.3° (0.0° to 10.5°). The use of the direct anterior approach resulted in significantly more variation in the alignment of the femoral component in both the coronal (1.3° vs 1.0°; p = 0.036) and sagittal planes (2.8° vs 2.0°; p = 0.012) compared with the use of the posterior approach. The posterior approach generally led to more anteversion of the acetabular component than the anterior approach. The use of robotics or navigation for positioning the acetabular compoment did not increase side-to-side variations in acetabular component-related positioning or leg length. Despite considerable side-to-side variations, the mean Hip disability and Osteoarthritis Outcome, Joint Replacement (HOOS JR) score was not affected by variations in the postioning of the components. CONCLUSION/UNASSIGNED:Staged bilateral THA resulted in considerable variation in the positioning of the components between the two sides. The direct anterior approach led to more variations in anteversion of the acetabular component and sagittal alignment of the femoral component than the posterior approach. The use of computer navigation and robotics did not improve the consistency of the positioning of the components in bilateral THA. Variations in the positioning of the components was not associated with differences in PROMs, indicating that patients can tolerate these differences.

BACKGROUND:Two-stage revisions for chronic periprosthetic joint infections (PJIs) often include antibiotic-loaded cement spacers to control for infection and preserve function. While studies have reported on complications (dislocations, readmissions, and reoperations) after static versus articulating spacer types, there is a paucity of evidence about whether the degree of spacer constraint in articulating spacers affects these complications. This study aims to address a key gap in understanding as to whether the level of spacer constraint affects complications in two-stage revision THA utilizing articulating spacers. QUESTIONS/PURPOSES/OBJECTIVE:(1) Among patients receiving nonconstrained versus constrained articulating antibiotic spacers during first-stage revision THA for PJI, are there differences in major complications, such as dislocation, loosening, periprosthetic fracture, reinfection, and unplanned revisions? (2) After second-stage reimplantation, do patients who received a nonconstrained versus constrained liner during the first stage show differences in the risk of complications, reoperations, and readmissions? METHODS:This is a retrospective review of 539 patients who underwent two-stage revision THA for PJI at a single-specialty, urban academic referral center between July 2011 and March 2023. Of these 539 patients, 72% (388) were excluded for undergoing a full component revision (femoral or acetabular) for any reason before their first stage, 3% (15) for receiving static spacers, and 6% (35) for receiving prefabricated femoral mono-block stems as part of their first stage. Those who underwent only liner exchange were not excluded. The remaining 19% (101 of 539) of patients were included in the final analysis and categorized by degree of liner constraint: 32 were in the nonconstrained group and 69 were in the constrained group. All surgeons included in this study specialize in adult reconstruction and are fellowship trained, and the selected level of constraint was solely based on their routine practice for articulating spacer construct. Baseline characteristics and clinical data, including age, self-reported gender, race, BMI, American Society of Anesthesiologists score, smoking status, surgical history, and perioperative details, were collected. There were no differences in baseline characteristics between the groups except for smoking status. A priori power analysis determined that 150 patients (75 per group) would be needed to detect a statistical difference in the risk of dislocation between groups, assuming a 20% dislocation risk for the constrained group, at a 0.05 alpha level, and 80% power. RESULTS:Between patients receiving nonconstrained versus constrained liners, there were no differences in complications after the first stage of revision. Three percent (1 of 32) of the nonconstrained liners developed dislocations compared with 3% (2 of 69) in the constrained group (relative risk [RR] 1.1 [95% confidence interval (CI) 0.09 to 12.3]; p > 0.99). Three percent (1 of 32) of the nonconstrained group developed periprosthetic fractures compared with 7% (5 of 69) in the constrained group (RR 0.4 [95% CI 0.05 to 3.69]; p = 0.72). Similarly, 3% (1 of 32) versus 7% (5 of 69) had persistent infection (RR 0.4 [95% CI 0.05 to 3.69]; p = 0.72). One incident of loosening occurred in the constrained group. There were also no differences in spacer revision incidence: 10% (3 of 32) of the nonconstrained group and 10% (7 of 69) of the constrained group underwent an unplanned revision after the first stage (RR 1.0 [95% CI 0.29 to 3.91]; p = 0.91). For the second stage, dislocation was 14% (3 of 21) in the nonconstrained group and 10% (5 of 52) in the constrained group (RR 1.1 [95% CI 0.2 to 5.9]; p > 0.99). When comparing periprosthetic fractures, 10% (2 of 21) of the nonconstrained group developed periprosthetic fractures compared with 4% (2 of 52) in the constrained group (RR 2.2 [95% CI 0.3 to 16.6]; p = 0.78). Nineteen percent (4 of 21) in the nonconstrained group had persistent infection compared with 12% (6 of 52) in the constrained group (RR 1.5 [95% CI 0.39 to 5.74]; p = 0.81). The occurrence of readmission after the second stage was 19% (4 of 21) in the nonconstrained group compared with 15% (8 of 52) in the constrained group (RR 1.1 [95% CI 0.3 to 3.9]; p > 0.99). Twenty-four percent (5 of 21) of patients in the nonconstrained group required a surgery-related emergency department visit compared with 13% (7 of 52) in the constrained group (RR 1.6 [95% CI 0.4 to 5.6]; p = 0.64). The incidence of reoperation was 14% (3 of 21) in the nonconstrained group and 13% (7 of 52) in the constrained group (RR 0.9 [95% CI 0.2 to 3.8]; p > 0.99). CONCLUSION/CONCLUSIONS:Our results indicated no differences in the risk of dislocations, reinfections, reoperations, and readmissions between patients undergoing constrained versus nonconstrained articulating spacers for two-stage revision THA. Because constrained liners are typically preferred in patients at higher risk of instability, our findings suggest that their use does not necessarily increase the risk of complications. However, because of the small sample size, larger studies are needed to demonstrate whether there is superiority of liner constraint in this patient population. LEVEL OF EVIDENCE/METHODS:Level III, therapeutic study.

BACKGROUND:Optimal femoral stem alignment and femoral canal fill have been associated with improved osteointegration in patients undergoing cementless total hip arthroplasty (THA). Direct anterior approach (DAA) has become more popular among new surgeons, and the ability to achieve appropriate stem alignment and canal fill due to limited surgical exposure may pose added risks. To mitigate these concerns, several modern tissue sparing stem designs have been designed. This study aimed to compare implant canal fill and alignment between two of the leading DAA-friendly femoral stems available. METHODS:This was a multi-center, retrospective study of patients who underwent DAA THA with either A (n = 149) or B stem (n = 85) between 2021 and 2023 and had a minimum one-year follow-up. Radiographic measures of proximal femoral morphology, including canal calcar ratio (CCR), Morphological Cortical Index (MCI), and Dorr Class (based on the CCR), as well as postoperative measures including femoral canal fill ratio (CFR), signs of osteointegration and stem alignment were analyzed and compared between stem types. RESULTS:, p = 0.082). Spot weld formation was significantly higher in stem A group (59.7% vs. 37.6%, P = 0.001). CONCLUSION/CONCLUSIONS:For patients with similar femoral morphology undergoing DAA THA, the stem A group demonstrated superior anatomical fit in the metaphyseal region, as evidenced by CFR, spot weld formation and implant positioning. Further longer follow up research is needed to elucidate these findings and their correlation to clinical outcomes.

BACKGROUND:Methylene blue (MB), a phenothiazine dye with antimicrobial activity, is used to stain soft tissues and guide thoroughness of debridement during revision total knee arthroplasty (rTKA) for periprosthetic joint infection (PJI). The purpose of this study was to determine if instillation of MB prior to arthrotomy impacts culture yield in TKA PJI. METHODS:We retrospectively reviewed 266 patients diagnosed with TKA PJIs according to the 2018 International Consensus Meeting (ICM) criteria from January 2018 - March 2023 at a single academic hospital. Demographics, perioperative outcomes, and preoperative and intraoperative culture positivity were compared between patients who received intraoperative MB (MB group; n = 26) and those who did not (nMB group; n = 241). A record of detected organisms was included in the analysis. RESULTS:There was no difference in preoperative aspiration culture positivity between groups. However, the MB group had a higher percentage of preoperative to intraoperative culture concordance (89.5 vs. 69.9%; P = 0.04). Although the overall rate of intraoperative culture positivity did not differ significantly between groups, the MB group had more intraoperative cultures obtained per patient (4.9 vs. 4.5; P = 0.02) and higher numbers of positive intraoperative cultures per patient. Concordance rates for patients in both groups with positive preoperative and negative intraoperative cultures were similar (10.5 vs. 16.5%, P = 0.50). Among patients with negative preoperative cultures, intraoperative culture positivity was more discordant in the MB group (0 vs. 18.8%; P = 0.03). There was no difference in the number of patients that received antibiotics following aspiration (68.4 vs. 49.6%; P = 0.12). CONCLUSION/CONCLUSIONS:While MB use did not affect overall culture positivity, it could interfere with intraoperative pathogen detection in patients with negative preoperative cultures. In these cases, MB should be avoided to decrease inaccuracies in intraoperative culture yield. If preoperative cultures are positive, MB may improve surgical debridement and likelihood of infection eradication.

BACKGROUND:High body mass index (BMI) is a risk factor for tibial baseplate loosening following total knee arthroplasty (TKA) but may not adequately correlate with stresses at the tibial baseplate. In this study, we aimed to determine an optimal cutoff of a weight-to-tibial baseplate surface-area ratio (weight/SA) for predicting aseptic tibial baseplate loosening. We further examined whether tibial stem extensions have a protective effect. METHODS:We identified 16,368 patients who underwent primary, elective TKA from June 2011 to March 2023. Patient demographics, including age, sex, and race, implants used, and revision surgeries were extracted. Revisions were manually reviewed to confirm revision indications. The exact surface areas of tibial baseplates were obtained from manufacturers. Receiver operating characteristic (ROC) analysis of patients without tibial stem extensions was utilized to examine the utility of BMI and weight/SA for predicting aseptic tibial baseplate loosening. Optimal weight/SA and BMI cutoffs for predicting loosening were determined. The effect of tibial stem extensions on loosening was then examined in patients at or above (n = 7,698; 3.7% with stem extension) and below (n = 8,670; 1.3% with stem extension) the determined weight/SA cutoff. RESULTS:There were 16,368 patients in the final sample (median age, 67 years; 68.9% female; 54.1% White). Weight/SA (area under the curve [AUC] = 0.653; p < 0.001) was a better predictor of aseptic tibial baseplate loosening requiring revision compared with patient BMI (AUC = 0.624; p < 0.001). The optimal weight/SA cutoff for predicting loosening was 0.0162 kg/mm2 (sensitivity = 0.747, specificity = 0.537). Multivariable logistic regression demonstrated that being at or above the weight/SA cutoff (odds ratio [OR] = 3.17; p < 0.001) but not the BMI cutoff (p = 0.911) was a significant predictor of revision for tibial baseplate loosening in patients without stem extensions. No cases of revision for aseptic tibial baseplate loosening in patients with stem extensions occurred either at or above or below the cutoff. The rate of revision for aseptic tibial baseplate loosening in patients without stem extensions was 0.3% for patients below and 1.0% for patients at or above the weight/SA cutoff. CONCLUSIONS:The ratio of weight-to-tibial baseplate surface area was more predictive of revision for aseptic tibial baseplate loosening following TKA compared with BMI alone. For patients with obesity with small tibial baseplate sizes, utilization of a tibial stem extension may protect against tibial loosening. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

INTRODUCTION/BACKGROUND:To our knowledge, outcomes of patients undergoing staged, bilateral total hip arthroplasty (THA) via dissimilar surgical approaches have not yet been investigated. This study examined demographics, implant selection, technology utilization, and component positioning between hips in patients who underwent one THA via posterior and one via direct anterior approach and secondarily evaluated patient-reported outcomes. METHODS:There were 36 patients (72 hips) who underwent staged, bilateral, primary, elective THAs via different approaches from January 2012 to December 2023. Patient demographics, intraoperative technology utilization, implants used, and pre- and postoperative Hip Dysfunction and Osteoarthritis Outcome Scores for Joint Replacement (HOOS-JR) scores were recorded. The hip center of rotation, acetabular height and anteversion, and metaphyseal canal fill were measured on postoperative radiographs. Femoral stem coronal and sagittal plane angulation following both approaches were also compared on postoperative radiographs. RESULTS:There were 15 (41.7%) patients who underwent posterior THA first. The mean time between operations was five years (range, 0.93 to 10.2). Intraoperative technology utilization was more common for the anterior THA (P = 0.002). There were no significant differences in hip center of rotation (P = 0.292), acetabular anteversion (P = 0.428), or acetabular height (P = 0.935) between patients' anterior and posterior approach THAs. The proportion of patients who had posterior stem angulation was significantly greater following anterior THA; neutral stem angulation was seen more frequently following posterior THA (P = 0.005). Lipped liners (P < 0.001), high offset femoral stems (P = 0.007), and dual or triple-taper stems (P < 0.001) were more commonly utilized in posterior THAs. For patients who had pre- and postoperative HOOS-JR for each hip, there was no significant difference in postoperative score improvement between anterior and posterior THAs (P = 0.697), with a mean follow-up time of 2.4 years (range, 0.3 to 9.28) for posterior and 6.1 years (range, 2.8 to 10.3) for anterior THAs (P = 0.249). CONCLUSIONS:Patients undergoing staged, bilateral THAs via different surgical approaches exhibit radiographic characteristics likely attributable to technical challenges for each approach. However, these differences related to approach do not seem to impact short-term clinical and patient-reported outcomes.

BACKGROUND:Obesity and diabetes mellitus (DM) pose challenges for patients undergoing total knee arthroplasty (TKA). Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as agents for weight and DM management, but they affect multiple organ systems. Outcomes, trends, and demographics for perioperative GLP-1RA use in patients with TKA are not well understood. METHODS:A retrospective review of 13,751 primary, elective TKAs with at least 90 days of follow-up at an urban academic health system between 2012 and 2023 identified 865 patients who had perioperative GLP-1RA use. A 10:1 propensity score match based on sex, age, smoking status, American Society of Anesthesiologists classification, and body mass index created a control cohort of 8,650 TKAs with no GLP-1RA use. RESULTS:The use of GLP-1RAs varied significantly by race, Medicaid insurance, Charlson Comorbidity Index, and presence of DM. Black and Latino patients and those covered by Medicaid were significantly less likely to receive GLP-1RAs. The GLP-1RA group had significantly shorter length of stay (2.1 versus 2.5 days, P < 0.001) and a higher rate of home discharge (91.7 versus 84.2%, P < 0.001). The GLP-1RA users had significantly higher rates of 90-day emergency department visits (5.9 versus 4.0%, P = 0.008), but no differences in 90-day readmissions (4.3 versus 3.6%, P = 0.168) or 2-year revision (2.3 versus 2.6%, P = 0.362) compared to matched controls. The GLP-1RA patients had significantly lower all-cause revision rates at the last follow-up (2.7 versus 3.9%, P = 0.034), but there was no significant difference in Kaplan-Meier implant survival (P = 0.311). Before TKA, GLP-1RA patients had an average decrease in body mass index of 0.4, compared to an average increase of 1.2 for matched controls. CONCLUSIONS:Our results demonstrate that the use of GLP-1RAs is significantly lower for minority patients and those covered by Medicaid. Patients using GLP-1RAs have noninferior clinical outcomes with the potential for weight loss leading up to TKA. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND:The cementation technique is crucial for achieving adequate fixation and optimal survivorship in total knee arthroplasty (TKA). The thickness of the cement at the tibial bone-implant surface may be related to aseptic tibial loosening. However, to date, no studies have demonstrated a direct association between cement thickness and rates of aseptic tibial loosening. METHODS:We performed a retrospective review to identify 28,327 primary cemented TKAs with at least 2 years of follow-up at an academic health system from 2013 to 2021. A total of 115 cases underwent revision surgery for aseptic tibial loosening. Cases where the implant was recalled specifically for loosening (n = 23) were excluded. The remaining 92 aseptic tibial loosening cases were 2:1 propensity score matched and implant matched to control patients who did not have tibial loosening. There were two independent reviewers who then measured the thickness of the cement interface in 10 locations along the bone-implant interface from initial postoperative radiographs. The averages of the reviewers' measurements were calculated and then compared using independent t-tests. RESULTS:Aseptic tibial loosening cases involving implant A tibial baseplate (n = 75) had significantly thinner cement interfaces than matched controls at all the 10 locations measured. Aseptic loosening cases involving implant B (n = 17) also displayed a thinner cement interface than matched controls in all locations, but this result was only statistically significant at the medial baseplate, medial keel, lateral keel, anterior keel, and posterior baseplate. CONCLUSIONS:In two widely used TKA systems, tibial aseptic loosening was associated with significantly thinner cement interfaces when compared to propensity-matched controls in two different implant types. Further prospective studies are needed to identify the optimal keel preparation and design as well as minimal cement interface thickness to avoid implant loosening. LEVEL OF EVIDENCE/METHODS:III.