Faculty Bibliography

Image-based robotic-assisted total knee arthroplasty (RA-TKA) allows three-dimensional surgical planning informed by osseous anatomy, with intraoperative adjustment based on a dynamic assessment of ligament laxity and gap balance. The aim of this study was to identify ranges of implant alignment and bone resections with RA-TKA. We retrospectively reviewed 484 primary RA-TKA cases, stratified by preoperative coronal alignment. Demographics and intraoperative data were collected and compared using Chi-square and ANOVA tests. Planned limb, femoral, and tibial alignment became increasingly varus in a progressive order from valgus to neutral to the highest in varus knees (p < 0.001). Planned external transverse rotation relative to the TEA was lowest in the valgus cohort; relative to the PCA, whereas the varus cohort was highest (p < 0.001, both). Planned resections of the lateral distal femur and of the medial posterior femur were greater in the varus group compared to neutral and valgus (p < 0.001). There were significant differences between cohorts in planned tibia resections, laterally and medially. Varus knees demonstrated higher variability, while valgus and neutral had more metrics with low variability. This study demonstrated trends in intraoperative planned alignment and resection metrics across various preoperative coronal knee alignments. These findings contribute to the understanding of RA-TKA and may inform surgical decision-making.

INTRODUCTION/UNASSIGNED:Total hip arthroplasty (THA) using computer-assisted navigation (N-THA) and robot-assisted surgery (RA-THA) has been increasingly adopted to improve implant positioning and offset/leg-length restoration. Whether clinically meaningful differences in patient-reported outcomes (PROMs) compared to conventional THA (C-THA) are achieved with intraoperative technology has not been established. This systematic review aimed to assess whether published relative PROM improvements with technology use in THA achieved minimal clinically important differences (MCIDs). METHODS/UNASSIGNED: 2786) studies, respectively, for analyses. RESULTS/UNASSIGNED:Statistically significant improvements in postoperative PROM scores were reported in 2/6 (33.3%) studies comparing N-THA with C-THA, though only 1 (16.7%) reported clinically significant relative improvements. Statistically significant improvements in postoperative PROMs were reported in 6/10 (60.0%) studies comparing RA-THA and C-THA, though none reported clinically significant relative improvements. Improved radiographic outcomes for N-THA and RA-THA were reported in 83.3% and 70.0% of studies, respectively. Only 1 study reported a significant improvement in revision rates with RA-THA as compared to C-THA. CONCLUSIONS/UNASSIGNED:Reported PROM scores in studies comparing N-THA or RA-THA to C-THA often do not achieve clinically significant relative improvements. Future studies reporting PROMs should be interpreted in the context of validated MCID values to accurately establish the clinical impact of intraoperative technology.

INTRODUCTION/BACKGROUND:Literature examining the risks, benefits, and potential complications of TKA in morbidly obese patients is conflicting. Surgeons with more experience performing TKA on morbidly obese patients may generate superior outcomes. This study sought to assess whether complication rates and implant survivorship in morbidly obese TKA patients varies between high (HV) and low (LV) volume surgeons. METHODS:A retrospective review was performed to include all morbidly obese (BMI ≥ 40) patients that underwent primary TKA between January 2016 and July 2021 at our high-volume center. Demographics and clinical outcomes were collected and compared between surgeons with a higher morbidly obese TKA volume (> 10 annual cases) and surgeons with a lower morbidly obese TKA volume. RESULTS:A total of 964 patients (HV 91 [9.4%], LV 873 [90.6%]) were identified. The HV surgeon and LV surgeons had an average annual volume of 15.3 and 5.2 cases, respectively. The average BMI for the HV and LV cohorts were 44.5 ± 3.7 and 44.0 ± 3.6, respectively (p = 0.160). The HV surgeon had significantly lower operative times (105.7 ± 17.4 vs. 110.7 ± 29.6 min, p = 0.018), and a lower 90-day minor complication rate (0.0% vs. 4.7%, p = 0.035). For patients with at least 2-year follow-up, all-cause revision (3.4% vs. 12.5%, p = 0.149) and revision due to PJI (0.0% vs. 5.8%, 0.193) rates were numerically lower in the HV cohort. Improvements in KOOS, JR and VR-12 scores were similar at 3-month and 1-year follow-up. Freedom from all-cause revision (HV: 96.6% vs. LV: 80.4%, p = 0.175) and revision due to PJI (HV: 100.0% vs. LV: 93.6%, p = 0.190, p = 0.190) at latest follow-up did not statistically differ between groups. CONCLUSION/CONCLUSIONS:The HV surgeon had significantly lower operative time and 90-day minor complication rates and numerically lower all-cause revision and revision due to PJI rates when performing TKA in morbidly obese patients. Surgeon's experience may affect surgical outcomes after TKA in morbidly obese patients. LEVEL OF EVIDENCE/METHODS:III.

Periprosthetic joint infections (PJIs) are a devastating complication of joint arthroplasty surgeries that are often complicated by biofilm formation. The development of biofilms makes PJI treatment challenging as they create a barrier against antibiotics and host immune responses. This review article provides an overview of the current understanding of biofilm formation, factors that contribute to their production, and the most common organisms involved in this process. This article focuses on the identification of biofilms, as well as current methodologies and emerging therapies in the management of biofilms in PJI.

BACKGROUND:The impact of increased patient comorbidities on the cost-effectiveness of total hip arthroplasty (THAs) is lacking. This study aimed to compare revenue, costs, and short-term (90 days) surgical outcomes between patients who have and do not have a high comorbidity burden (HCB). METHODS:We retrospectively reviewed 14,949 patients who underwent an elective, unilateral THA between 2012 and 2021. Patients were stratified into HCB (Charlson Comorbidity Index ≥ 5 and American Society of Anesthesiology scores of 3 or 4) and non-HCB groups, and were further 1:1 propensity matched based on baseline characteristics. Perioperative data, revenue, costs, and contribution margins (CMs) of the inpatient episode were compared between groups. Also, 90-day readmissions and revisions were compared between groups. Of the 11,717 patients who had available financial data (n = 1,017 HCB, n = 10,700 non-HCB), 1,914 patients were included in the final matched analyses (957 per group). RESULTS:Total (P < .001) and direct (P < .001) costs were significantly higher for HCB patients. Comparable revenue between cohorts (P = .083) resulted in a significantly decreased CM in the HCB patient group (P < .001). The HCB patients were less likely to be discharged home (P < .001) and had significantly higher 90-day readmission rates (P = .049). CONCLUSIONS:Increased THA costs for HCB patients were not matched by increased revenue, resulting in decreased CM. Higher rates of nonhome discharge and readmissions in the HCB population add to the additional financial burden. Adjustments to the current reimbursement models should better account for the increased financial burden of HCB patients undergoing THA and ensure access to care for all patient populations. LEVEL OF EVIDENCE/METHODS:III.

INTRODUCTION/UNASSIGNED:Spinopelvic mobility drives functional acetabular position, influencing dislocation risk after total hip arthroplasty (THA). Patients have been described as "stuck sitting" or "stuck standing" based on pelvic tilt (PT). We hypothesised that some patients are "stuck in the middle," meaning their PT changes minimally from sitting to standing - increasing their risk of dislocation. METHODS/UNASSIGNED:We reviewed 195 patients with standing and sitting whole body radiographs prior to THA. Standing anterior pelvic plane tilt (APPT) and standing and sitting sacral slope (SS) were measured and used to calculate sitting APPT. Normal standing and sitting were defined as APPT >-10° and <-20°, respectively. Spinal stiffness was classified as <10° change in sacral slope between sitting and standing. Patients were categorised as: (A) able to fully sit and stand; (B) "stuck sitting" - able to fully sit; unable to fully stand; (C) "stuck standing" - able to fully stand; unable to fully sit; or (D) "stuck in the middle" - unable to sit or stand fully. RESULTS/UNASSIGNED:84 patients could sit and stand normally (A), 22 patients were stuck sitting (B), 76 patients were stuck standing (C), and 13 patients were stuck in the middle (D). While 111 patients (56.9%) were considered stuck, only 58 patients (29.7%) met criteria for spinal stiffness. DISCUSSION/UNASSIGNED:We identified a subset of patients with stiff spines and abnormal PT in both sitting and standing, including 37.1% of patients who would be classified as "stuck sitting" based only on standing radiographs. Placing acetabular components in less than anatomic anteversion in these patients may increase posterior dislocation risk.

BACKGROUND:Computer navigation and robotic assistance may reduce total hip arthroplasty (THA) dislocations by improving the accuracy and precision of component positioning. We investigated dislocation rates for THAs using conventional techniques, robotic assistance, and computer navigation, while controlling for surgical approach, dual mobility (DM) use, and fluoroscopic guidance. METHODS:We reviewed 11,740 primary THAs performed between June 2016 and December 2022, including 5,873 conventional, 1,293 with robotic-arm assistance, and 4,574 with navigation. The approach was posterior in 6,580 (56.0%), anterior in 4,342 (37.0%), and lateral in 818 (7.0%). A DM was used in 10.4%. Fluoroscopy was used in 3,653 cases and only with the anterior approach. Multivariate analyses yielded odds ratios (OR) for dislocation and revision. Additional regression analyses for dislocation were performed for approach and DM. RESULTS:Raw dislocation rates were as follows: conventional 1.2%, robotic 0.4%, navigation 0.9%, anterior with fluoroscopy 0.4%, anterior without fluoroscopy 2.3%, posterior 1.3%, and lateral 0.5%. Upon multivariate analysis, use of robotics was found to be associated with significantly reduced dislocation risk compared to conventional (OR: 0.3), as did anterior (OR: 0.6) compared to posterior approach; navigation and lateral approach were not found to be associated with a significant reduction in risk. For the anterior approach, multivariate analysis demonstrated that fluoroscopy significantly reduced dislocation risk (OR: 0.1), while DM, robotics, and navigation were not significant. For the posterior approach, the dislocation risk was lower with robotics than with conventional (OR: 0.2); the use of navigation or DM did not demonstrate a significant reduction in risk. CONCLUSIONS:The use of robotics was associated with a reduction in dislocations for this cohort overall. Further, fluoroscopy in the anterior approach and robotic assistance in the posterior approach were both associated with decreased dislocation risk. The role of imageless computer navigation and DM implants requires further study.

BACKGROUND:With the increasing utilization of total hip arthroplasty (THA) in patients who have a high comorbidity burden (HCB), coinciding with modifications to reimbursement models over the past decade, an evaluation of the financial impact of HCB on THA over time is warranted. This study aimed to investigate trends in revenue and cost associated with THA in HCB patients. METHODS:Of 13,439 patients who had primary, elective THA between 2013 and 2021 at our institution, we retrospectively reviewed 978 patients considered to have HCB (Charlson comorbidity index ≥ 5 and American Society of Anesthesiology scores 3 or 4). We collected patient demographics, perioperative data, revenue, cost, and contribution margin (CM) of the inpatient episode. We analyzed changes as a percentage of 2013 values over time for these financial markers. Linear regression determined trend significance. The final analysis included 978 HCB patients who had complete financial data. RESULTS:Between 2013 and 2021, direct costs increased significantly (P = .002), along with a nonsignificant increase in total costs (P = .056). While revenue remained steady during the study period (P = .486), the CM decreased markedly to 38.0% of 2013 values, although not statistically significant (P = .222). Rates of 90-day complications and home discharge remained steady throughout the study period. CONCLUSIONS:Increasing costs for HCB patients undergoing THA were not matched by an equivalent increase in revenue, leading to dwindling CMs throughout the past decade. Re-evaluation of reimbursement models for THA that account for patients' HCB may be necessary to preserve broad access to care. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND:Previous data suggest that obesity does not impact surgical outcomes following total knee arthroplasty performed by high-volume (HV) surgeons. However, this effect has yet to be studied in total hip arthroplasty (THA) patients. This study aimed to evaluate the impact of patient obesity on THA outcomes when surgery is performed by HV surgeons. METHODS:A retrospective analysis of patients who underwent primary, elective THA between January 2012 and December 2022 with a HV surgeon (top 25% of surgeons by number of annual primary THA) was performed. Patients were stratified by their body mass index (BMI) into 3 cohorts: BMI ≥ 40 (morbidly obese [MO]), 30 ≤ BMI < 40 (obese), and BMI < 30 (nonobese); and 1:1:1 propensity matched based on baseline characteristics. A total of 13,223 patients were evaluated, of which 669 patients were included in the final matched analysis (223 patients per group). The average number of annual THAs performed for HV surgeons was 171 cases. RESULTS:The MO patients had significantly longer surgical times (P < .001) and hospital lengths of stay (P < .001). Rates of 90-day readmissions (P = .211) and all-cause, septic, and aseptic revisions at the latest follow-up (P = .268, P = .903, and P = .168, respectively) were comparable between groups. In a subanalysis for non-HV surgeons, MO patients had a significantly greater risk of revision (P = .021) and trended toward significantly greater readmissions (P = .056). CONCLUSIONS:Clinical outcomes and complication rates after THA performed by a HV surgeon are similar regardless of patient obesity status. Patients who have MO may experience improved outcomes and reduced procedural risks if they are referred to HV surgeons. LEVEL OF EVIDENCE/METHODS:III.