Faculty Bibliography

INTRODUCTION/BACKGROUND:Arthrofibrosis remains a common cause of patient dissatisfaction and reoperation after total knee arthroplasty (TKA). Losartan is an angiotensin receptor blocker (ARB) with inhibitory effects on transforming growth factor beta, previously implicated in tissue repair induced fibrosis, and has been studied to prevent stiffness following hip arthroscopy. This study aimed to evaluate pre- and postoperative range of motion (ROM) and the incidence of manipulation under anesthesia (MUA) following primary TKA in patients taking Losartan preoperatively for hypertension. MATERIALS AND METHODS/METHODS:A retrospective review of 170 patients from 2012 to 2020 who underwent a primary, elective TKA and were prescribed Losartan at least three months prior to surgery. All patients who were prescribed Losartan and had a preoperative and postoperative ROM in their chart were included and were matched to a control group of patients who underwent TKA and had no Losartan prescription. ROM, MUA, readmissions, reoperations, and revisions were assessed using chi-square and independent sample t tests. RESULTS:Seventy-nine patients met the inclusion criteria. Preoperative ROM was similar between patients on Losartan and the control group (103.59° ± 16.14° vs. 104.59° ± 21.59°, respectively; p = 0.745). Postoperative ROM and ΔROM were greater for patients prescribed Losartan (114.29° ± 12.32° vs. 112.76° ± 11.65°; p = 0.429 and 10.57° ± 14.95° vs. 8.17° ± 21.68°; p = 0.422), though this difference did not reach statistical significance. There was no difference in readmission, rate of manipulation for stiffness, or all-cause revision rates. CONCLUSION/CONCLUSIONS:In this study, we found that the use of Losartan did not significantly improve postoperative ROM, reduce MUA or decrease revision rates. Further prospective studies using Losartan are required to elucidate the potential effects on ROM and incidence of arthrofibrosis requiring MUA. LEVEL III EVIDENCE/METHODS:Retrospective cohort study.

BACKGROUND:As value-based reimbursement models mature, understanding the potential trade-off between inpatient lengths of stay and complications or need for costly post-acute care becomes more pressing. Understanding and predicting a patient's expected baseline length of stay may help providers understand how best to decide optimal discharge timing for high-risk total joint arthroplasty (TJA) patients. MATERIALS AND METHODS/METHODS:A retrospective review was conducted of 37,406 primary total hip (17,134, 46%) and knee (20,272, 54%) arthroplasties performed at two high-volume, geographically diverse, tertiary health systems during the study period. Patients were stratified by 3 binary outcomes for extended inpatient length of stay: 72+ hours (29%), 4+ days (11%), or 5+ days (5%). The predictive ability of over 50 sociodemographic/comorbidity variables was tested. Multivariable logistic regression models were created using Institution #1 (derivation), with accuracy tested using the cohort from Institution #2 (validation). RESULTS:During the study period, patients underwent an extended length of stay with a decreasing frequency over time, with privately-insured patients having a significantly shorter length of stay relative to those with Medicare (1.9 vs 2.3 days, p < 0.0001). Extended-stay patients also had significantly higher 90-day readmission rates (p < 0.0001), even when excluding those discharged to post-acute care (p < 0.01). Multivariable logistic regression models created from the training cohort demonstrated excellent accuracy (area under the curve (AUC): 0.755, 0.783, 0.810), and performed well under external validation (AUC: 0.719, 0.743, 0.763). Many important variables were common to all 3 models, including age, sex, American Society of Anesthesiologists (ASA) score, body mass index, marital status, bilateral case, insurance type, and 13 comorbidities. DISCUSSION/CONCLUSIONS:An online, freely-available, pre-operative clinical decision tool accurately predicts risk of extended inpatient length of stay after TJA. Many risk factors are potentially modifiable, and these validated tools may help guide clinicians in pre-operative patient counseling, medical optimization, and understanding optimal discharge timing.

INTRODUCTION/BACKGROUND:The International Classification of Diseases-10 Procedure Code System (ICD-10-PCS) introduced oxidized zirconium and niobium (OxZi) procedural codes to the types of femoral head bearing surfaces in 2017. These codes aimed to increase procedural specificity in coding and improve data collection through administrative claims databases. This study aimed to assess the accuracy of ICD-10-PCS coding for femoral head bearing surfaces (cobalt chrome/metal, ceramic, and OxZi) in hip procedures. MATERIAL AND METHODS/METHODS:, 2021 at a large, urban academic hospital was conducted. Operative reports and implant logs were queried to determine the femoral head bearing surface, which was used during the THA. These results were then compared to the ICD-10-PCS codes in the billing records. Coding accuracy was subsequently determined and statistical differences between the three groups were evaluated. RESULTS:ICD-10-PCS coding was accurate for 90.8% (5634/6204) of cases. Coding accuracy for ceramic femoral heads (95.4%, 4171/4371) was significantly greater than that of both cobalt chrome/metal (73.7%, 606/822; p<0.001) and OxZi (84.8%, 857/1011; p<0.001) femoral heads. CONCLUSION/CONCLUSIONS:While coding for ceramic femoral heads was very accurate, OxZi and cobalt chrome/metal femoral heads were miscoded at a rate of approximately 20%. These inaccuracies call for further evaluation of the ICD-10-PCS coding process to ensure that conclusions drawn from clinical research performed through administrative claims databases are not subject to error.

BACKGROUND:Some studies have shown lower morbidity and mortality rates with increased surgeon and hospital volumes after total hip arthroplasty (THA). This study sought to determine the relationship between surgeon and hospital volumes and patient-reported outcome measures after THA using American Joint Replacement Registry data. METHODS:Using American Joint Replacement Registry data from 2012 to 2020, 4,447 primary, elective THAs with both preoperative and 1-year postoperative Hip Dysfunction and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR) scores were analyzed. This study was powered to detect the minimum clinically important difference (MCID). The main exposure variables were median annual surgeon and hospital volumes. Tertiles were formed based on the median annual number of THAs conducted: low-volume (1 to 42), medium-volume (42 to 96), and high-volume (≥96) surgeons and low-volume (1 to 201), medium-volume (201 to 392), and high-volume (≥392) hospitals. Mean preoperative and 1-year postoperative HOOS-JR scores were compared. RESULTS:Preoperative HOOS-JR scores were significantly higher at high-volume hospitals than low-volume and medium-volume hospitals (49.66 ± 15.19 vs. 47.68 ± 15.09 and 48.34 ± 15.22, P < 0.001), although these differences were less than the MCID. At the 1-year follow-up, no difference was noted with no resultant MCID. Preoperative and 1-year HOOS-JR scores did not markedly vary with surgeon volume. In multivariate regression, low-volume and medium-volume surgeons and hospitals had similar odds of MCID achievement in HOOS-JR scores compared with high-volume surgeons and hospitals, respectively. CONCLUSION/CONCLUSIONS:Using the HOOS-JR score as a validated patient-reported outcome measure, higher surgeon or hospital THA volume did not correlate with higher postoperative HOOS-JR scores or greater chances of MCID achievement in HOOS-JR scores compared with medium and lower volume surgeons and hospitals.

BACKGROUND:Supervised machine learning techniques have been increasingly applied to predict patient outcomes after hip and knee arthroplasty procedures. The purpose of this study was to systematically review the applications of supervised machine learning techniques to predict patient outcomes after primary total hip and knee arthroplasty. METHODS:A comprehensive literature search using the electronic databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews was conducted in July of 2021. The inclusion criteria were studies that utilized supervised machine learning techniques to predict patient outcomes after primary total hip or knee arthroplasty. RESULTS:Search criteria yielded n = 30 relevant studies. Topics of study included patient complications (n = 6), readmissions (n = 1), revision (n = 2), patient-reported outcome measures (n = 4), patient satisfaction (n = 4), inpatient status and length of stay (LOS) (n = 9), opioid usage (n = 3), and patient function (n = 1). Studies involved TKA (n = 12), THA (n = 11), or a combination (n = 7). Less than 35% of predictive outcomes had an area under the receiver operating characteristic curve (AUC) in the excellent or outstanding range. Additionally, only 9 of the studies found improvement over logistic regression, and only 9 studies were externally validated. CONCLUSION/CONCLUSIONS:Supervised machine learning algorithms are powerful tools that have been increasingly applied to predict patient outcomes after total hip and knee arthroplasty. However, these algorithms should be evaluated in the context of prognostic accuracy, comparison to traditional statistical techniques for outcome prediction, and application to populations outside the training set. While machine learning algorithms have been received with considerable interest, they should be critically assessed and validated prior to clinical adoption.

INTRODUCTION/BACKGROUND:Loosening and migration are common modes of aseptic failure following complex revision total knee arthroplasty (rTKA). Metaphyseal cones allow surgeons to negotiate the loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing rTKA utilizing a novel metaphyseal cone system with stems of variable length and fixation methods. METHODS:This two-center retrospective study examined all patients who underwent rTKA with a novel porous, titanium tibial or femoral cone in combination with a stem of variable length and fixation who had a minimum follow-up of 2-years. Outcome analysis was separated into tibial and femoral cones as well as the stem fixation method (hybrid vs. fully cemented). RESULTS:Overall, 123 patients who received 156 cone implants were included (74 [60.2%] tibial only, 16 [13.0%] femoral only, and 33 [26.8%] simultaneous tibial and femoral) with a mean follow-up of 2.76 ± 0.66 years. At 2-years of follow-up the total cohort demonstrated 94.3% freedom from all-cause re-revisions, 97.6% freedom from aseptic re-revisions, and 99.4% of radiographic cone osteointegration. All-cause revision rates did not differ between stem fixation techniques in both the tibial and femoral cone groups. CONCLUSION/CONCLUSIONS:The use of a novel porous titanium femoral and tibial metaphyseal cones combined with stems in patients with moderate to severe bone defects undergoing complex revision total knee arthroplasty confers excellent results independent of stem fixation technique. LEVEL OF EVIDENCE/METHODS:IV, case series.

AIM/OBJECTIVE:Posterior stabilized (PS) and varus valgus constrained (VVC) knee polyethylene liners have been shown to confer excellent long-term functional results following revision total knee arthroplasty (rTKA). The purpose of this study was to compare outcomes of patients who underwent rTKA using either a PS or VVC liner. METHODS:A retrospective comparative study of 314 rTKA with either PS or VVC liner and a minimum follow-up time of two years was conducted. Patient demographics, complications, readmissions, and re-revision etiology and rates were compared between groups. Kaplan-Meier survivorship analysis was performed to estimate freedom from all-cause revision. RESULTS:Hospital LOS (3.41 ± 2.49 vs. 3.34 ± 1.93 days, p = 0.793) and discharge disposition (p = 0.418) did not significantly differ between groups. At a mean follow-up of 3.55 ± 1.60 years, the proportion of patients undergoing re-revision did not significantly differ (19.1% vs. 18.7%, p = 0.929). In subgroup analysis of re-revision causes, the VVC cohort had superior survival from re-revision due to instability compared to the PS cohort (97.8% vs. 89.4%, p = 0.003). Freedom from re-revision due to aseptic loosening did not significantly differ between groups (85.2% vs. 78.8%, p = 0.436). Improvements in range of motion (ROM) from preoperative to latest follow-up were similar as well. CONCLUSIONS:PS and VVC liners confer similar survivorship, complication rates, and overall knee ROM in rTKA. VVC liners were not associated with increased postoperative aseptic loosening and demonstrated superior freedom from re-revision due to instability. Future studies with longer follow-up are warranted to better determine significant differences in clinical outcomes between the two bearing options. LEVEL III EVIDENCE/METHODS:Retrospective Cohort Study.

BACKGROUND:The growing variety of total hip arthroplasty implants necessitates a standardized, simple, and brand-neutral language to precisely classify femoral components. Although previous classifications have been useful, they need updating to include stems that have current surface treatment technologies, modularity, collar features, and other geometric characteristics. METHODS:To accomplish this, we propose a new classification system for stems based on 3 distinguishing stem features: (1) geometry, (2) location of modularity, and (3) length. RESULTS:Our system allows for the easy classification of all currently used stem types. CONCLUSIONS:One goal of this endeavor is to improve clinical record keeping to facilitate study comparisons as well as literature reviews.

INTRODUCTION/BACKGROUND:Despite the excellent outcomes associated with primary total hip arthroplasty (THA), implant failure and revision continue to burden the healthcare system. The use of computer-assisted navigation (CAN) offers the potential for more accurate placement of hip components during surgery. While intraoperative CAN systems have been shown to improve outcomes in primary THA, their use in the context of revision total hip arthroplasty (rTHA) has not been elucidated. We sought to investigate the validity of using CAN during rTHA. METHODS:A retrospective analysis was performed at an academic medical institution identifying all patients who underwent rTHA using CAN from 2016-2019. Patients were 1:1 matched with patients undergoing rTHA without CAN (control) based on demographic data. Cup anteversion, inclination, change in leg length discrepancy (ΔLLD) and change in femoral offset between pre- and post-operative plain weight-bearing radiographic images were measured and compared between both groups. A safety target zone of 15-25° for anteversion and 30-50° for inclination was used as a reference for precision analysis of cup position. RESULTS:Eighty-four patients were included: 42 CAN cases and 42 control cases. CAN cases displayed a lower ΔLLD (5.74 ± 7.0 mm vs 9.13 ± 7.9 mm, p = 0.04) and greater anteversion (23.4 ± 8.53° vs 19.76 ± 8.36°, p = 0.0468). There was no statistical difference between the proportion of CAN or control cases that fell within the target safe zone (40% vs 20.9%, p =  0.06). Femoral offset was similar in CAN and control cases (7.63 ± 5.84 mm vs 7.14 ± 4.8 mm, p = 0.68). CONCLUSION/CONCLUSIONS:Our findings suggest that the use of CAN may improve accuracy in cup placement compared to conventional methodology, but our numbers are underpowered to show a statistical difference. However, with a ΔLLD of ~ 3.4 mm, CAN may be useful in facilitating the successful restoration of pre-operative leg length following rTHA. Therefore, CAN may be a helpful tool for orthopedic surgeons to assist in cup placement and LLD during complex revision cases.