Phase 1 study of the pharmacokinetics and clinical proof-of-concept activity of a biofilm-disrupting human monoclonal antibody in patients with chronic prosthetic joint infection of the knee or hip.

We report the results of a first-in-human phase 1 clinical study to evaluate TRL1068, a native human monoclonal antibody that disrupts bacterial biofilms with broad-spectrum activity against both Gram-positive and Gram-negative species. The study population consisted of patients with chronic periprosthetic joint infections (PJIs) of the knee or hip, including both monomicrobial and polymicrobial infections, that are highly resistant to antibiotics due to biofilm formation. TRL1068 was administered via a single pre-surgical intravenous infusion in three sequentially ascending dose groups (6, 15, and 30 mg/kg). Concomitant perioperative antibiotics were pathogen-targeted as prescribed by the treating physician. In this double-blinded study, 4 patients were randomized to receive placebo and 11 patients to receive TRL1068 on day 1, as well as targeted antibiotics for 7 days prior to the scheduled removal of the infected implant and placement of an antibiotic-eluting spacer as the first stage of the standard of care two-stage exchange arthroplasty. No adverse events attributable to TRL1068 were reported. TRL1068 serum half-life was 15-18 days. At day 8, the concentration in synovial fluid was approximately 60% of the blood level and thus at least 15-fold above the threshold for biofilm-disrupting activity in vitro. Explanted prostheses were sonicated to release adherent bacteria for culture, with elimination of the implant bacteria observed in 3 of the 11 patients who received TRL1068, which compares favorably to prior PJI treatments. None of the patients who received TRL1068 had a relapse of the original infection by the end of the study (day 169). CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT04763759.

Comparison of total elbow arthroplasty complications between various surgical indications at 90-day and 1-year follow-up in 1600 elbows.

BACKGROUND: Total elbow arthroplasty (TEA) was traditionally a mainstay of treatment for patients with severe inflammatory arthritis. Recently, the indications for TEA have expanded, and TEA has grown into a versatile procedure that can be used to treat several pathologies of the elbow. The objective of this study was to compare complication rates between TEAs performed for rheumatoid arthritis (RA), fracture (FX), or osteoarthritis (degenerative joint disease [DJD]). METHODS: A retrospective analysis of the MUExtr data set of the PearlDiver national database was performed. International Classification of Diseases, Tenth Revision codes were used to identify patients who underwent TEA from 2010-2020 and to separate them into RA, FX, and DJD cohorts. Demographic characteristics, comorbidities, and hospital data were identified and compared using analysis of variance. Systemic complications at 90 days and surgical complications at both 90 days and 1 year were compared using multivariable logistic regression. Surgical complications included wound dehiscence, hematoma, deep infection, periprosthetic FX, stiffness, instability, triceps injury, nerve injury, and need for revision. RESULTS: We identified 1600 patients (DJD, 38.9%; FX, 48.8%; and RA, 12.3%). The majority of patients in all 3 cohorts were female patients, with the RA group having a significantly higher percentage of female patients than the FX and DJD groups (87.3% vs. 81.4% and 76.9%, respectively; P = .003). No significant differences in systemic complications and surgical complications were noted between all 3 groups at 90 days postoperatively. After controlling for patient factors, FX patients were more likely to have elbow stiffness (odds ratio, 1.53; P = .006) and less likely to have a triceps injury (odds ratio, 0.26; P < .001) at 1 year than were RA or DJD patients. CONCLUSION: The indications for TEA have expanded over the past 10 years, with nearly half of all cases being performed for FX. At 1 year postoperatively, TEAs performed for FX have a significantly lower rate of triceps injury and higher rate of elbow stiffness than TEAs performed for other indications. This finding is important to consider when preoperatively planning, as well as when discussing expected outcomes with patients prior to surgery, especially with the expanded incidence of TEA for FX being performed over the past decade.

Renal Transplant Patients Have a Lower Risk of Complications and Mortalities After Total Knee Arthroplasty Compared to Those on Hemodialysis: A Large National Database Study.

BACKGROUND: Total knee arthroplasty (TKA) in end-stage renal disease is associated with complications. Controversy exists whether elective TKA should be performed while patients are on hemodialysis (HD) or following renal transplant (RT). This study compares TKA outcomes in HD versus RT patients. METHODS: A national database was retrospectively reviewed using International Classification of Diseases codes to identify HD and RT patients who underwent primary TKA from 2010 to 2018. Demographics, comorbidities, and hospital factors were compared using Wald and Chi-squared tests. The primary outcome was in-hospital mortalities while secondary outcomes included quality outcomes and medical/surgical complications. Multivariate regressions were used to determine independent associations. Significance was determined with a 2-tailed P value of .05. There were 13,611 patients who underwent TKA (61.1 HD and 38.9% RT). Patients who had RT were younger, had fewer comorbidities, and more likely to have private insurance. RESULTS: The RT patients had a lower rate of mortality (odds ratio (OR) 0.23, P < .01)), complications (OR 0.63, P < .01), cardiopulmonary complications (OR 0.44, P = .02), sepsis (OR 0.22, P < .001), and blood transfusion (OR 0.35, P < .001) during the index hospitalization. This cohort was also found to have decreased length of stay (-2.0 days, P < .001), non-home discharge (OR 0.57, P < .001), and hospital cost (-$5,300, P < .001). Patients who had RT had a lower rate of readmission (OR 0.54, P < .001), periprosthetic joint infection (OR 0.50, P < .01), and surgical site infection (OR 0.37, P < .001) within 90 days. CONCLUSION: These findings suggest that HD patients are a high-risk population in TKA compared to RT patients and warrant stringent perioperative monitoring.

Short-term outcomes of periprosthetic compared to native distal femur fractures, a national database study.

BACKGROUND: Distal femur fractures (DFFx) are highly morbid injuries with a complication rate comparable to hip fractures. Rising rates of total knee arthroplasty (TKA) have led to increasing rates of periprosthetic DFFx (pDFFx). We sought to determine how pDFFx complication rates differed from native DFFx (nDFFx). METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was used to identify patients who sustained pDFFx or nDFFx between 2012 and 2018. Patients were further stratified by operative treatment: open reduction internal fixation (ORIF) or distal femur replacement (DFR). Multivariate logistic regression was used to compare 30-day complication rates between pDFFx versus nDFFx and, among pDFFx patients, ORIF versus DFR or revision TKA (rTKA). RESULTS: 563 patients with pDFFx and 2259 patients with nDFFx were identified between 2012 and 2018. pDFFx patients had significantly lower rates of ORIF than nDFFx patients (36.4 vs 95.4%, p < 0.001). On multivariate analysis, pDFFx were associated with a higher rate of surgical site complications (OR 2.48, p = 0.009) compared to nDFFx. There were no differences in mortality, reoperations, major complications, rate of blood transfusion, venous thromboembolism and disposition. In patients with pDFFx, patients undergoing DFR/rTKA were more likely to be discharged home versus a rehab facility, compared to those undergoing ORIF (OR 2.62, p < 0.001). CONCLUSIONS: In this first large registry study comparing pDFFx and nDFFx, we find similar outcomes between these groups in the first 30 days after surgery. Patients with pDFFx did have higher rates of surgical site complications, including infection and dehiscence. In pDFFx patients, those undergoing DFR were more likely to return home post-operatively.

Comparison of complication profiles for femoral neck, intertrochanteric, and subtrochanteric geriatric hip fractures.

INTRODUCTION: Most geriatric hip fractures occur in the femoral neck (FN) and intertrochanteric (IT) regions of the femur, while a minority occur in the subtrochanteric (ST) region. Relative outcomes based on the anatomical subtype of fracture are not well studied. This study characterizes postoperative complications and outcomes of hip fractures distinguished by anatomic region. MATERIALS AND METHODS: The targeted hip fracture series of the American College of Surgeons National Surgical Quality Improvement Program database was queried to identify geriatric (≥ 65 years) patients who sustained operative FN, IT, and ST hip fractures. Primary patient demographic and perioperative data were collected and correlated with 30-day postoperative complications and outcomes. Multivariate regression was used to calculate relative risks of adverse events (AEs) between groups. RESULTS: In total, 8220 geriatric hip fracture patients were identified. Risk-adjusted 30-day mortality was not significantly different between patients with ST (5.8%, p = 0.735) and IT (7.3%, p = 0.169) femur fractures relative to those with FN fractures (6.6%). The overall risk-adjusted rate of minor and major medical AEs within 30 days and risk-adjusted rate of wound complications was not significantly different between FN, IT, and ST fractures. Patients with IT [34.4%, OR 2.35 (2.35-3.08), p < 0.001] and ST fractures [49.8%, OR 5.94 (4.58-7.70), p < 0.00] had higher risk-adjusted incidence of postoperative blood transfusion relative to FN fractures (18.5%). Furthermore, patients with IT fractures had a slightly lower risk-adjusted incidence of unplanned reoperation [2.1 vs. 2.7%, OR 0.69 (0.47-0.99), p = 0.046] and hospital readmission (7.8 vs. 9.2%, OR 0.76 [0.63-0.91], p = 0.003) than patients with FN fractures. CONCLUSIONS: With respect to anatomic region, geriatric hip fractures have similar short-term mortality and medical AE profiles with differences in transfusion, reoperation, and readmission rates. Knowledge of these short-term outcomes may guide surgeons in counseling hip fracture patients peri-operatively.

Navigated and Robot-Assisted Technology in Total Knee Arthroplasty: Do Outcome Differences Achieve Minimal Clinically Important Difference?

BACKGROUND: In total knee arthroplasty (TKA), computer-assisted navigation (N-TKA) and robotic-assisted methods (RA-TKA) are intended to increase precision of mechanical and component alignment. However, the clinical significance of published patient-reported outcome measure (PROM) differences in comparison to conventional TKA (C-TKA) is unknown. METHODS: A systematic review was performed to identify all studies reporting perioperative PROMs for either primary N-TKA or RA-TKA with a C-TKA comparison cohort with a minimum 1-year follow-up. Relative improvements in PROMs for the two cohorts were compared to published minimal clinically important difference (MCID) values. RESULTS: After systematic review, 21 studies (N = 3,214) reporting on N-TKA and eight studies (N = 1,529) reporting on RA-TKA met inclusion criteria. Eighteen of 20 studies (90%) reported improved radiographic outcomes with N-TKA relative to C-TKA; five of five studies reported improved radiographic outcomes with RA-TKA relative to C-TKA. Five of 21 studies (24%) reported statistically significant greater improvements in clinical PROMs for N-TKA relative to C-TKA, whereas only two (10%) achieved clinical significance relative to MCID on a secondary analysis. One of 8 studies (13%) reported statistically significant greater improvements in PROMs for RA-TKA relative to C-TKA, whereas none achieved clinical significance relative to MCID on a secondary analysis. No studies reported a significant difference in revision rates. CONCLUSION: While most studies comparing RA-TKA and N-TKA with C-TKA demonstrate improved radiographic alignment outcomes, a minority of studies reported PROM differences that achieve clinical significance. Future studies should report data and be interpreted in the context of clinical significance to establish patient and surgeon expectations for emerging technologies.

Hip Arthroplasty Outcomes for Femoral Neck Fractures in Transplant Patients.

BACKGROUND: The purpose of this study was to compare the short-term complications between transplant and nontransplant patients who undergo hip arthroplasty for femoral neck fractures (FNFs). Additionally, we sought to further compare the outcomes of total hip arthroplasty (THA) versus hemiarthroplasty (HA) within the transplant group. METHODS: This was a retrospective review utilizing the Nationwide Readmissions Database. Transplant patients were identified and stratified based on transplant type: kidney, liver, or other (heart, lung, bone marrow, and pancreas). Outcomes of interest included index hospitalization mortality, perioperative complications, length of stay, costs, hospital readmission, and surgical complications within 90 days of discharge. RESULTS: From 2010 to 2018, a total of 881,061 patients underwent THA or HA for FNFs, of which 2163 (0.2%) were transplant patients. When compared with nontransplant patients, all transplant patients had an increased risk of requiring blood transfusion (odds ratio [OR] = 1.51, P = .001), acute kidney injury (OR = 2.02, P < .001), and discharge to facility (OR = 1.67, P = .001) while having increased index hospitalization length of stay and costs. Liver and other transplant patients had an increased risk of readmission within 90 days (OR = 1.82, P < .001 and OR = 1.60, P = .014 respectively). Subgroup analysis for transplant patients comparing HA with THA demonstrated no differences in perioperative complication rates and decreased hospitalization length of stay and cost associated with THA. CONCLUSION: In this retrospective cohort study, transplant patients had an increased risk of requiring blood transfusions and acute kidney injury after hip arthroplasty for FNFs. There were no differences in short-term complications between transplant patients treated with HA versus THA. LEVEL OF EVIDENCE: 3 (Retrospective cohort study).

Analysis of perioperative outcomes in hip resection arthroplasty.

BACKGROUND: Hip resection arthroplasty (HRA) is a salvage surgical technique for the management of complex hip conditions wherein arthroplasty may be contraindicated. The purpose of this study was to review modern-day indications for HRA and compare outcomes between patients undergoing HRA and revision total hip arthroplasty (RTHA). METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was used to identify patients undergoing HRA or RTHA between 2012 and 2017. Patient demographics, risk factors, and perioperative complications were analyzed. Multivariate regression was used to determine predictors of early postoperative complications. Propensity score matching (PSM) was performed to compare relative risks (RR) of complications in HRA compared to RTHA. RESULTS: 290 patients underwent HRA between 2012 and 2017. Infection was the most common indication for HRA (39.8%), followed by femoral neck fracture or malunion/nonunion (26%) and prosthetic instability (12.2%). Increased body mass index (BMI) (p = 0.012) and chronic obstructive pulmonary disease (COPD) (p = 0.007) were associated with increased risk of complication in HRA. There were no significant differences in short-term complication risks between RTHA and HRA. CONCLUSIONS: HRA was associated with short-term complication rates comparable to RTHA. These findings may help in surgical decision-making and appropriate indications in the present day. LEVEL OF EVIDENCE: III.

Does Physical Activity Level Influence Total Hip Arthroplasty Expectations, Satisfaction, and Outcomes?

BACKGROUND: Total hip arthroplasty (THA) patients expect pain relief and functional improvement, including return to physical activity. Our objective was to determine the impact of patients' physical activity level on preoperative expectations and postoperative satisfaction and clinical outcomes in patients undergoing THA. METHODS: Using an institutional registry of patients undergoing THA between 2007 and 2012, we retrospectively identified patients who underwent unilateral primary THA for osteoarthritis and completed a preoperative Lower Extremity Activity Scale, Hospital for Special Surgery Hip Replacement Expectations Survey, and Hip disability and Osteoarthritis Outcome Score in addition to two-year HOOS and satisfaction evaluations. Active patients (n = 1053) were matched to inactive patients (n = 1053) by age, sex, body mass index, and comorbidities. The cohorts were compared with regard to the association of expectations with Hip disability and Osteoarthritis Outcome Score and satisfaction, the change in Lower Extremity Activity Scale level from baseline to 2 years, complications, and revision surgical procedures. RESULTS: Significantly more active patients (74%) expected to be "back to normal" regarding ability to exercise and participate in sports compared with inactive patients (64%, P < .001). Overall satisfaction was similar. Higher expectations with regard to exercise and sports were associated with higher HOOS sports and recreation subdomain scores in active patients. The inactive patient group improved on baseline activity level at 2 years while the active group did not. CONCLUSION: At 2 years after THA, active and inactive patients were similarly satisfied and achieved comparable outcomes. Inactive patients showed a greater improvement in physical activity level from preoperative baseline than active patients. Complications and revision rates were similar. LEVEL OF EVIDENCE: III.

Effect of Parkinson's Disease on Hemiarthroplasty Outcomes After Femoral Neck Fractures.

BACKGROUND: The purpose of this study was to evaluate the outcomes following hemiarthroplasty (HA) for femoral neck fractures (FNFs) in patients with Parkinson's disease (PD) compared with patients without PD. METHODS: This was a retrospective review utilizing the Nationwide Readmissions Database, a national database incorporating inpatient hospitalization information. Using the Nationwide Readmissions Database, patients who underwent HA for FNF between 2010-2014 were identified. International Classification of Diseases, 9th Revision, codes were used to find a subset of patients with PD. Primary outcomes of interest included death, hospital readmission, periprosthetic fracture, postoperative dislocation, any revision surgery, and revision surgery for instability, fracture, or infection. RESULTS: There were a total of 7721 (4%) patients with PD. There was no difference in the risk of death or any postoperative complications during index hospitalization for these patients. However, PD patients had an increased risk of hospital readmission (odds ratio [OR] = 1.13, 95% confidence interval [CI]: 1.02-1.26) and postoperative dislocation (OR = 2.10, 95% CI: 1.58-2.80) within 90 days of surgery. PD patients also had an increased risk of revision surgery for instability (OR = 2.20, 95% CI: 1.48-3.28), despite no difference in the risk of any revision surgery, revision surgery for fracture, or revision surgery for infection. CONCLUSION: In this retrospective cohort study, PD patients who underwent a HA for FNF had a greater risk of postoperative dislocation and revision surgery for instability within 90 days. These findings are not only important to consider when managing these at-risk patients but also stress the need to allocate operative and postoperative resources to prevent and treat instability. LEVEL OF EVIDENCE: 3 (Retrospective cohort study).

Patient-Reported Outcome Measures of Total Knee Arthroplasties for Post-Traumatic Arthritis versus Osteoarthritis: A Short-Term (5- to 10-year) Retrospective Matched Cohort Study.

BACKGROUND: The objective of the study was to compare the patient-reported outcome measures (PROM) of patients with post-traumatic arthritis (PTA) versus patients with osteoarthritis (OA) undergoing total knee arthroplasty (TKA) and compare the rates of revision among these two groups. METHODS: Using a prospectively held institutional registry, we retrospectively reviewed patients ≥60 years of age who underwent unilateral TKA between May 2007 and February 2012. Patients with previous or concomitant diagnosis of inflammatory arthropathy or an initial open fracture were excluded. PTA patients were matched 1:5 with OA patients undergoing TKA. Validated PROMs were recorded at baseline before index TKA and the last follow-up. Reason and time to revision surgery was reported, and survivorship was compared using Kaplan-Meier curves. RESULTS: Seventy-five PTA patients were matched to 375 OA patients. There was no difference between these groups with respect to age (67.7 ± 5.6 vs 67.8 ± 5.5 years; P = .876), body mass index (28.6 ± 5.4 vs 28.7 ± 5.3 kg/m2; P = .948), sex (65.3% vs 65.3% females; P = .999), Charlson Comorbidity Index (21.3% vs 21.3% Index 1-2, P = .999), and time to follow-up (93.0 ± 13.4 vs 88.2 ± 13.7 months; P = .999). No statistically significant difference was found in PROMs at baseline and the last follow-up (P > .05), the rate or time to revision surgery between the two groups (P-value = .635; log-rank test). CONCLUSION: Unlike previous studies, TKA for PTA does not pose lower PROMs or higher revision rates when compared to TKA for OA. These results could help provide surgeons with a frame of reference in terms of expectations for patients with PTA undergoing TKA.

Bilateral Total Hip Arthroplasty has Similar Complication Rates to Unilateral Total Hip Arthroplasty.

Simultaneous bilateral THA has several advantages over staged THA, however its safety has not been well examined. This study reports a statewide 15-year experience of simultaneous bilateral THA and compares its complications to those of unilateral THA. Logistic regression was used to determine the role of bilateral surgery as a predictor of complications while correcting for patient comorbidities. Of 202,986 patients, 1.1% underwent bilateral THA. Bilateral THA was more commonly performed in males, younger patients, those with private insurance, and at higher volume hospitals. There was no difference in 30-day readmissions or revision surgeries. There was a higher rate of sepsis in the bilateral group but no difference in other complications. This study demonstrates that THA is a safe option in appropriately selected patients.

Combination prophylactic therapy with rifampin increases efficacy against an experimental Staphylococcus epidermidis subcutaneous implant-related infection.

The incidence of infections related to cardiac devices (such as permanent pacemakers) has been increasing out of proportion to implantation rates. As management of device infections typically requires explantation of the device, optimal prophylactic strategies are needed. Cefazolin and vancomycin are widely used as single agents for surgical prophylaxis against cardiac device-related infections. However, combination antibiotic prophylaxis may further reduce infectious complications. To model a localized subcutaneous implant-related infection, a bioluminescent strain of Staphylococcus epidermidis was inoculated onto a medical-procedure-grade titanium disc, which was placed into a subcutaneous pocket in the backs of mice. In vivo bioluminescence imaging, quantification of ex vivo CFU from the capsules and implants, variable-pressure scanning electron microscopy (VP-SEM), and neutrophil enhanced green fluorescent protein (EGFP) fluorescence in LysEGFP mice were employed to monitor the infection. This model was used to evaluate the efficacies of low- and high-dose cefazolin (50 and 200 mg/kg of body weight) and vancomycin (10 and 110 mg/kg) intravenous prophylaxis with or without rifampin (25 mg/kg). High-dose cefazolin and high-dose vancomycin treatment resulted in almost complete bacterial clearance, whereas both low-dose cefazolin and low-dose vancomycin reduced the in vivo and ex vivo bacterial burden only moderately. The addition of rifampin to low-dose cefazolin and vancomycin was highly effective in further reducing the CFU harvested from the implants. However, vancomycin-rifampin was more effective than cefazolin-rifampin in further reducing the CFU harvested from the surrounding tissue capsules. Future studies in humans will be required to determine whether the addition of rifampin has improved efficacy in preventing device-related infections in clinical practice.

Does-dual mobility still offer improved stability in smaller cup sizes? A computer modelling comparison of stability with 22-mm versus 28-mm inner heads in dual-mobility versus single-bearing constructs.

PURPOSE: Dislocation remains 1 of the leading causes of revision after primary total hip arthroplasty (THA) and there is clear evidence the dual-mobility (DM) is used more frequently to minimise this. But in smaller cups, whether the use of DM with smaller 22-mm heads imparts any increased stability compared to standard bearing is unknown; especially when those smaller cups now allow for large single-bearing (SB) heads. METHODS: 3 primary cup sizes (48 mm, 50 mm, 52 mm) were chosen a priori for modelling. Head sizes trialled for the standard bearing (SB) constructs group were 28-0 mm, 32-0 mm and 36-0 mm against neutral polyethylene liners. In the modular sub-hemispheric DM constructs the inner head sizes for the DM constructs were altered where appropriate (22-0 mm vs. 28-0 mm). Cup position, stem offset, and stem size were standardised. RESULTS: Both DM constructs outperformed all SB constructs because of a statistically significant jump distance increase (p < 0.001). However, there was no difference in range of motion (ROM) or jump distances between the 22-mm and 28-mm DM inner heads.The ROM angle before impingement between the DM (with 22-mm or 28-mm heads) and SB (with different head sizes where appropriate) showed no statistically significant difference. However, DM constructs presented significantly larger jump distances than SB constructs for both provocative dislocation tests across all 3 cup sizes.Of interest, for 50-mm and 52-mm cup sizes (for which this particular DM construct design can accommodate both 22-mm and 28-mm inner heads), there were no differences in ROM or jump distance between 22-mm versus 28-mm inner heads. CONCLUSIONS: In this computer-modelling study, DM constructs are advantageous over SB constructs for improving jump distances in clinically provocative positions, but not range of motion angles. Inner head diameter of DM has no effect on stability.

Point-of-Care Coating of Revision Femoral Stems With Antibiotic-Loaded Calcium Sulfate: Reduction in Infection After 2nd Stage Reimplantation but Not With Aseptic Revisions.

Background: Infection rates in revision total hip arthroplasty are lower when antibiotic loaded cemented stems are utilized. Inspired by this technique, a point-of-care coating of antibiotic-loaded calcium sulfate (CaSO4) was applied to cementless revision stems in aseptic revision and 2nd stage reimplantation total hip arthroplasty. Methods: One hundred eleven consecutive femoral stems were coated. Just prior to insertion, 10 cc of CaSO4 was mixed with 1 g vancomycin and 240 mg tobramycin with the paste applied to the stem. The results were compared to a matched cohort (N = 104) performed across the previous 5 years. The surgical methods were comparable, but for the stem coating. The study group was followed for a minimum of 3 years. Results: In the study cohort of 111 patients, there were 69 aseptic revisions with one periprosthetic joint infection (PJI) (1.4%) and 42 second-stage reimplantations with 2 PJIs (4.8%). In the control cohort of 104 patients, there were 74 aseptic revisions with one PJI (1.4%) and 30 second-stage reimplantations with 7 PJIs (23.3%). There was no significant reduction in PJI rate in the aseptic revision subgroup (1.4% study vs 1.4% control group), P = 1.000. Antibiotic stem coating reduced PJI rate in the 2nd stage reimplantation subgroup (23.3% control vs 4.8% study group), P = .028. In both groups, there were no cases of aseptic stem loosening. Conclusions: Point-of-care antibiotic coating of cementless revision femoral stems reduces PJI infection rate in 2nd stage reimplantations only. We theorize that microbes persist in the endosteal cortices after resection and may contribute to infection recurrence.

Understanding infection: a primer on animal models of periprosthetic joint infection.

Periprosthetic joint infections are devastating complications for patients and for our health system. With growing demand for arthroplasty, the incidence of these infections is projected to increase exponentially. This paper is a review of existing animal models to study periprosthetic infection aimed at providing scientists with a succinct presentation of strengths and weaknesses of available in vivo systems. These systems represent the tools available to investigate novel antimicrobial therapies and reduce the clinical and economic impact of implant infections.

End-stage renal disease patients have comparable results to renal transplant patients after shoulder arthroplasty.

Background: End-stage renal disease (ESRD) and renal transplant (RT) patients are known to have more perioperative and postoperative complications after arthroplasty surgeries when compared to patients without. We hypothesize that RT patients undergoing shoulder arthroplasty (SA) have fewer systemic and surgical complications when compared to ESRD patients undergoing SA. Methods: This was a retrospective review from the PearlDiver Patient Record Database. International Classification of Diseases and Current Procedural Terminology codes were used to identify patients who had undergone primary total and reverse shoulder arthroplasty, respectively, and subsequent surgical revisions. Unadjusted univariate analysis of patient demographics, Charlson Cormorbidty Index, and surgical complications at 90 days, 1 year, and 2 years after was performed using chi-squared testing. Multivariate logistic regression analyses were subsequently performed for systemic complications and prosthesis outcomes at all time points. Results: Of 1191 patients with ESRD or previous RT and who underwent either total shoulder arthroplasty or reverse total shoulder arthroplasty, 1042 (87.5%) had ESRD and 149 (12.5%) had a previous RT. ESRD SA patients were more likely to have hypertension, liver disease, coronary artery disease, and hypothyroidism. Interestingly no statistical significance was found in multivariate analysis for systemic complications at 90 days, nor for surgical complications at the 90-day, 1-year, or 2-year mark between ESRD and RT cohorts. Conclusion: SAs have comparable outcomes in ESRD and RT patients. The differing conclusions among studies might be partially accounted for by the demographic differences and comorbidities between these 2 patient populations. Providers should continue to provide appropriate counseling concerning risks, benefits, and timing of SA for these patients.

MELD score predicts short-term outcomes after surgical management of proximal humerus fractures: a matched analysis.

Objective: We aimed to evaluate the difference in 30-day outcomes after surgical management of proximal humerus fractures (PHFs) between patients with and without chronic liver disease as defined by a MELD score greater than 10. Design: This was a retrospective database review. Setting: All centers participating in the American College of Surgeons National Surgical Quality Improvement Program database were included. Patients/Participants: Patients with proximal humerus fractures who (1) underwent ORIF, HA, or SA and (2) had calculable MELD scores were included. Intervention: Open reduction and internal fixation, hemiarthroplasty, or shoulder arthroplasty was used for treatment. Main outcome measurements: Thirty-day complications, mortality, readmission, and reoperation rates were measured. Results: Of the total 1732 PHF patients identified, 300 had a MELD score higher than 10. After propensity matching by significant covariates, MELD score higher than 10 was found to be significantly associated with higher rates of 30-day mortality, 30-day readmission, transfusion within 72 hours, and systemic complications. Among patients with a MELD score higher than 10, treatment with SA or HA instead of ORIF was associated with a higher rate of transfusion and longer operative time. There were no significant differences between treatment cohorts regarding mortality, reoperation, readmission, or complications. Conclusions: A MELD score higher than 10 is associated with higher risk of surgical complications, transfusion, and death in patients undergoing surgery for proximal humerus fractures. Among patients with a MELD score higher than 10, ORIF was associated with a lower transfusion rate and shorter operative time than arthroplasty or hemiarthroplasty. Level of Evidence: Prognostic Level III.

Prosthetic Limb Attachment via Electromagnetic Attraction through a Closed Skin Envelope.

OBJECTIVE: Current socket-based methods of prosthetic limb attachment are responsible for many of the dominant problems reported by persons with amputation. In this work, we introduce a new paradigm for attachment via electromagnetic attraction between a bone-anchored ferromagnetic implant and an external electromagnet. Our objective was to develop a design framework for electromagnetic attachment, and to evaluate this framework in the context of transfemoral amputation. METHODS: We first used inverse dynamics to calculate the forces required to suspend a knee-ankle-foot prosthesis during gait. We then conducted cadaveric dissections to inform implant geometry and design a surgical methodology for covering the implant. We also developed an in silico framework to investigate how electromagnet design affects system performance. Simulations were validated against benchtop testing of a custom-built electromagnet. RESULTS: The physical electromagnet matched simulations, with a root-mean-square percentage error of 4.2% between measured and predicted forces. Using this electromagnet, we estimate that suspension of a prosthesis during gait would require 33 W of average power. After 200 and 1000 steps of simulated walking, the temperature at the skin would increase 2.3℃ and 15.4℃ relative to ambient, respectively. CONCLUSION: Our design framework produced an implant and electromagnet that could feasibly suspend a knee-ankle-foot prosthesis during short walking bouts. Future work will focus on optimization of this system to reduce heating during longer bouts. SIGNIFICANCE: This work demonstrates the initial feasibility of an electromagnetic prosthetic attachment paradigm that has the potential to increase comfort and improve residual limb health for persons with amputation.