Faculty Bibliography

INTRODUCTION/BACKGROUND:Obtaining an accurate preoperative diagnosis of periprosthetic joint infections (PJI) is challenging, making differentiating between septic and aseptic failures difficult. We sought to identify the value of common serum biomarkers and evaluate the accuracy of three ratios in the diagnosis of PJI after primary total knee arthroplasty (TKA): albumin-globulin ratio (AGR), C-reactive protein-albumin ratio (CAR), and C-reactive protein-AGR ratio (CAGR). METHODS:Patients undergoing PJI and aseptic revisions after TKA between 2011 and 2021 were retrospectively reviewed at a single institution. Only patients who had reported serum white blood cell (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), albumin (Alb), and total protein (TP) were included. Areas under the curve (AUCs), which optimize diagnostic performance by balancing sensitivity and specificity at a specific cutoff, were calculated for each individual biomarker and the three ratio groups: AGR = Alb / [TP - Alb], CAR = CRP / Alb, and CAGR = CRP / AGR). Higher AUCs indicate improved identification of PJI while reducing misclassification. RESULTS:Out of the 126 included cases, 89 were confirmed PJIs and 37 were aseptic revisions. Among the single and combination serum biomarkers, the AUCs were as follows: CRP (0.85), ESR (0.76), Alb (0.81), AGR (0.78), CAR (0.87), and CAGR (0.87). The CAR demonstrated excellent accuracy at a cutoff of 2.46, with a sensitivity of 0.74 and specificity of 0.84. CAGR also demonstrated excellent accuracy at a cutoff of 7.09, with a sensitivity of 0.80 and specificity of 0.78. CONCLUSION/CONCLUSIONS:The CRP, CAR, and CAGR showed an excellent diagnostic accuracy as markers for PJI. In patients undergoing revision TKA, common serum biomarkers such as Alb, TP, CRP, and ESR can be obtained, and CAR or CAGR ratios can be calculated to aid in the diagnosis of PJI, especially in cases where synovial analysis is inconclusive, allowing for better clinical decision-making.

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.

The efficacy of "Expanded Gram-Negative Antimicrobial Prophylaxis" (EGNAP) in preventing postoperative infections has been previously reported in total hip arthroplasty (THA). However, it remains unclear as to whether these benefits extend to total knee arthroplasty (TKA). This study investigated whether adding EGNAP to our institution's preoperative antibiotic prophylaxis protocol would affect periprosthetic joint infection (PJI) risk in TKA patients. We retrospectively reviewed 10,666 elective, unilateral, primary TKA cases performed at a single-specialty tertiary academic hospital from 2018 to 2022. Before June 2021, all patients received 2 g of cefazolin for 24 h as part of the prophylactic antibiotic protocol. After June 2021, gentamicin or aztreonam (EGNAP) was added to the protocol for all TKA patients. Patients were grouped based on whether they received EGNAP or not (control group) before surgery. The groups were propensity score-matched in a 2:1 ratio. PJI and nephrotoxicity (using RIFLE criteria) risk was compared. After matching, the final study population consisted of 3007 patients in the non-EGNAP group and 1503 patients in the EGNAP group. There was no significant difference between the EGNAP and no EGNAP groups in the overall incidence of PJI (1.9% vs. 2.0%; p = 0.111) or the incidence of Gram-positive PJIs (0.3% vs. 0.8%; p = 0.103). The incidence of Gram-negative PJIs was 0.5% in the EGNAP group and 0.4% in the no EGNAP group, which was also not different between the groups (p = 0.692). There were no differences in nephrotoxicity between groups (p = 0.521). The addition of EGNAP to the antibiotic prophylactic protocol prior to TKA had no effect on overall or Gram-negative PJI risk in TKA patients. The findings of this study suggest that while EGNAP is safe to use and has minimal nephrotoxic effects, its prophylactic benefits do not extend to the primary TKA population. This may be attributed to the generally low rate of Gram-negative infections in TKA patients, where adding EGNAP does not provide a clear advantage in reducing the risk of such infections, unlike its potential benefits in primary THA population. This study investigates the effects of using prophylactic Gram-negative antibiotics prior to TKA and shows that though it is safe to use, Gram-negative bacterial coverage may have no impact on postoperative infection incidence.

OBJECTIVE:This study assesses the impact of a structured summer externship program (SEP) in orthopedic surgery on participants' career trajectories and diversity within the field. Specifically, we evaluated the proportion of SEP participants who chose a career in orthopedic surgery and analyzed trends in gender and racial/ethnic diversity among the cohort over a 20-year period. DESIGN/METHODS:A retrospective cohort analysis was conducted using data from participants in 1 academic department's SEP between 2004 and 2023. Participant demographic data, ultimate specialty match information, and residency outcomes were collected and statistically analyzed to assess trends in specialty selection, gender, and racial/ethnic diversity among the SEP alumni. SETTING/METHODS:This study took place in the Department of Orthopedic Surgery at a large academic tertiary medical center. PARTICIPANTS/METHODS:The study included 564 medical students who participated in the SEP between 2004 and 2023. Of these, 441 (78.2%) have graduated from medical school to date, 114 (20.2%) are still enrolled, and 5 (0.89%) have left medicine for careers in other sectors. Data for 9 participants (1.6%) was unavailable. RESULTS:Among the 436 graduates, 161 (36.9%) eventually matched into orthopedic surgery. An additional 13.5% entered internal medicine, 7.3% matched into radiology, 6.6% into emergency medicine, 5.5% into anesthesiology, and 30.3% into various other specialties. Female representation in the SEP increased from 16.6% in 2004 to 51.1% in 2023 (χ² = 4.95, p = 0.026), while non-white participant representation grew from 16.6% to 45% over the same period (χ² =3.18, p = 0.075). CONCLUSIONS:The SEP is one way of providing resources and opportunity for engagement for students interested in orthopedic surgery careers while promoting diversity within the field. This program serves as a valuable pathway, offering early exposure to orthopedic surgery, research opportunities, and professional networking, all of which may play an increasingly critical role as residency selection criteria evolve. The SEP's advantages to participants underscore the importance of targeted programs in fostering opportunity for previously underrepresented groups in the field of orthopedic surgery.

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: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:Despite advances in surgical techniques and postoperative prophylactic protocols, venous thromboembolism (VTE) events remain an important source of morbidity following total hip arthroplasty (THA). Prior research in cardiology and other surgical fields has suggested that statin medications may have a protective effect against VTE. Our study aimed to: 1) Assess if preoperative statin use was associated with decreased rates of VTE following THA, and 2) conduct a subgroup analysis of statin intensity and VTE events. METHODS:A total of 1,154 patients who had preoperative statin use for at least four weeks before surgery and who underwent primary THA at a large, urban academic center between January 1, 2012, and June 1, 2023, were identified. The 90-day postoperative VTE events, deep vein thrombosis (DVT), pulmonary embolism (PE), emergency department (ED) visits, reoperations, and readmission rates were collected from institutional coding software. Mortality rate in the 90-day postoperative period was also measured. Propensity matching was used to control for demographics and selected comorbidities. RESULTS:Preoperative statin use was associated with significantly lower rates of 90-day VTE events (Statin: 0.43% versus No-Statin: 1.13%, P = 0.047). There were no significant differences in 90-day PE, DVT, ED visit, readmission, or reoperation rates. There were no deaths within 90 days of THA in either group. Subgroup analysis of statin intensity revealed no significant differences in any outcomes measured between high-intensity, medium-intensity, and low-intensity statin groups. CONCLUSION/CONCLUSIONS:Preoperative statin use is associated with significantly lower rates of VTE events in the 90-day postoperative period following THA. Further research into the effect of statins on post-THA VTE is warranted.

INTRODUCTION/BACKGROUND:The role of advanced imaging in diagnosing aseptic implant loosening following total hip arthroplasty (THA) remains unclear. This study aimed to assess the diagnostic value of magnetic resonance imaging (MRI) in detecting aseptic loosening. METHODS:This was a retrospective review of 342 consecutive patients who underwent revision THA between July 2011 and April 2023 and had a pelvis MRI as part of the preoperative diagnostic evaluation. Among them, 62 patients had an intraoperative diagnosis of aseptic loosening of either the femoral or acetabular component. Patients were stratified based on the concordance between their MRI and radiographs findings. RESULTS:Preoperative MRI showed signs of aseptic loosening in 25/62 patients (sensitivity = 40.3%). Similarly, preoperative radiographs demonstrated signs of aseptic loosening in 27 patients (43.5%). Twelve patients (19.4%) had both MRI and radiographs predictive of aseptic loosening, 22 patients (35.5%) did not show signs of aseptic loosening in either MRI or radiographs, and for 28 patients (45.2%), the results were discordant. Among the patients with a negative radiograph for aseptic loosening (n = 35), 13 patients (37.1%) showed signs of aseptic loosening on MRI. CONCLUSION/CONCLUSIONS:Aseptic loosening remains an elusive diagnosis, and the findings of this study suggest that the utility of MRI and radiographs as part of the diagnostic process is limited. However, in cases of presumed aseptic loosening with inconclusive radiographs findings, MRI may play a role in improving the diagnostic process. LEVEL OF EVIDENCE/METHODS:III.

INTRODUCTION/BACKGROUND:Debridement, antibiotics, and implant retention (DAIR) are the mainstays surgical treatment for acute periprosthetic joint infection (PJI). However, re-operation following DAIR is common, and the risk factors for DAIR failure remain unclear. This study aimed to assess the perioperative characteristics of patients who failed initial DAIR treatment. METHODS:A retrospective review was conducted on 83 patients who underwent DAIR for acute PJI within three months following index surgery from 2011 to 2022, with a minimum one-year follow-up. Surgical outcomes were categorized using the Musculoskeletal Infection Society (MSIS) outcome reporting tool (Tiers 1 to 4). Patient demographics, laboratory data, and perioperative outcomes were compared between patients who had failed (Tiers 3 and 4) (n = 32) and successful (Tiers 1 and 2) (n = 51) DAIR treatment. Logistic regression was also performed. RESULTS:After logistic regression, Charlson Comorbidity Index (CCI) (odds ratio (OR): 1.57; P = 0.003), preoperative C-reactive protein (CRP) (OR: 1.06; P = 0.014), synovial white blood cell (WBC) (OR: 1.14; P = 0.008), and polymorphonuclear cell (PMN%) counts (OR: 1.05; P = 0.015) were independently associated with failed DAIR. Compared with total hip arthroplasty (THA), total knee arthroplasty (TKA) patients (OR: 6.08; P = 0.001) were at increased risk of DAIR failure. The type of organism and time from primary surgery were not correlated with DAIR failure. CONCLUSION/CONCLUSIONS:Patients who had failed initial DAIR tended to have significantly higher CCI, CRP, synovial WBC, and PMN%. The TKA DAIRs were more likely to fail than the THA DAIRs. These characteristics should be considered when planning acute PJI management, as certain patients may be at higher risk for DAIR failure and may benefit from other surgical treatments.

BACKGROUND:Lumbar spinal fusion (LSF) is a risk factor for dislocation following total hip arthroplasty (THA). The effect of the surgical approach on this association has not been investigated. This study examined the association between the surgical approach and dislocation following THA in patients who had prior LSF. METHODS:We retrospectively reviewed 16,223 primary elective THAs at our institution from June 2011 to September 2022. Patients who had LSF prior to THA were identified using International Classification of Diseases (ICD) codes. Patients were stratified by LSF history, surgical approach, and intraoperative robot or navigation use to compare dislocation rates. There were 8,962 (55.2%) posterior, 5,971 (36.8%) anterior, and 1,290 (8.0%) laterally based THAs. Prior LSF was identified in 323 patients (2.0%). Binary logistic regressions were used to assess the association of patient factors with dislocation risk. RESULTS:There were 177 dislocations identified in total (1.1%). In nonadjusted analyses, the dislocation rate was significantly higher following the posterior approach among all patients (P = .003). Prior LSF was associated with a significantly higher dislocation rate in all patients (P < .001) and within the posterior (P < .001), but not the anterior approach (P = .514) subgroups. Multivariate regressions demonstrated anterior (OR [odds ratio] = 0.64, 95% CI [confidence interval] 0.45 to 0.91, P = .013), and laterally based (OR = 0.42, 95% CI 0.18 to 0.96, P = .039) approaches were associated with decreased dislocation risk, whereas prior LSF (OR = 4.28, 95% CI 2.38 to 7.69, P < .001) was associated with increased dislocation risk. Intraoperative technology utilization was not significantly associated with dislocation in the multivariate regressions (OR = 0.72, 95% CI 0.49 to 1.06, P = .095). CONCLUSIONS:The current study confirmed that LSF is a significant risk factor for dislocation following THA; however, anterior and laterally based approaches may mitigate dislocation risk in this population. In multivariate analyses, including surgical approach, LSF, and several perioperative variables, intraoperative technology utilization was not found to be significantly associated with dislocation risk.