Faculty Bibliography

BACKGROUND: Postoperative pain after total knee arthroplasty (TKA) poses a major challenge. It delays mobilization, increases opioid consumption and side effects, and lengthens hospitalization. This challenge multiplies when treating an opioid-dependent population. We examined whether a novel suspended release local anesthetic, liposomal bupivacaine (LB) would improve pain control and decrease opioid consumption after TKA compared to a standard periarticular injection in opioid-dependent patients. METHODS: Thirty-eight patients undergoing TKA were randomly assigned to receive either a periarticular injection (PAI) with LB (n = 20) or with a standard PAI (including a combination of ropivacaine, clonidine, Toradol, Epinepherine, and saline; n = 18) as part of a multimodal pain management approach. All periarticular injections were done by a single surgeon. Perioperative treatment was similar between groups. Postoperative information regarding pain level was evaluated by a pain visual analog scale score. Postoperative opioid consumption was recorded. RESULTS: After controlling baseline narcotic usage before surgery, no differences were found between groups in daily postoperative narcotic usage (P = .113), average daily pain score (P = .332), or maximum daily pain score (P = .881). However, when examining pain levels separately for each day, pain visual analog scale scores were reported higher in post operative day 1 in the LB group (P = .033). CONCLUSIONS: LB was not found to be superior to standard PAI in opioid-dependent patients undergoing TKA. This patient population continues to present a challenge even with modern multimodal pain protocols.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most common causes of revision total hip arthroplasty (THA) and associated with higher costs, prolonged pain, and worse clinical outcomes. Many factors have been linked to increased infection rates, one being the operative equipment and instrumentation used during the surgical procedure. With few arthroplasty instruments designed for complete disassembly and increasingly complex instrument designs, this study seeks to understand the effect that instrument disassembly plays on infection using disassembled and assembled standard femoral broach handles (BHs). METHODS: Two BHs, not designed for disassembly, were modified and then contaminated in the disassembled state with Geobacillus stearothermophilus vegetative-form bacteria and spores. Using both flash and standard sterilization cycles, the BHs were steam sterilized in the disassembled or assembled state and then analyzed for remaining bacteria and spores. RESULTS: At all target locations after either a flash sterilization cycle or a standard sterilization cycle, complete eradication of both the vegetative-form and spore-form of G stearothermophilus was achieved. CONCLUSION: This study demonstrates that adequate decontamination of the tested BHs can be achieved after steam sterilization in either the disassembled or assembled state, without an increased risk of infection transmission.

BACKGROUND: Previously, our group successfully established one of the nation's first Perioperative Surgical Homes (PSHs) aimed at coordinating services to patients undergoing primary total hip arthroplasty (THA) and primary total knee arthroplasty (TKA). As we now focus on extending the PSH to other service lines within the hospital, the long-term sustainability of this practice model is an important factor to consider moving forward. METHODS: We prospectively collected data from all patients who underwent elective primary TKA and THA at our institution between October 1, 2012, and September 30, 2014. Prospectively collected data included length of stay (LOS), 30-day readmission rate, postoperative pain scores, and complications. RESULTS: During the 2-year period, there were 328 primary joint arthroplasty patients. Overall, the median LOS was significantly shorter in the second year of the PSH initiative (P = 0.03). Stratified by procedure, the median LOS for patients undergoing THA was significantly shorter in the second year (P = 0.02), whereas the median LOS for patients undergoing TKA did not differ between the 2 time periods. In the second year of the PSH initiative, significantly more patients were discharged home than to a skilled nursing facility compared with year 1 of the PSH initiative (P = 0.02). Readmission rates within 30 days after surgery to our institution were 0.9% (0.0-4.4) in the first year of the PSH initiative and 3.3% (confidence interval, 1.3%-7.2%) in the second year of the PSH initiative (P = not significant). Pain scores did not change significantly from year 1 to year 2 (P = not significant). CONCLUSIONS: Data for the second year of implementation demonstrate similarly positive results in LOS, pain control, discharge destination, readmission, transfusion rates, and complications.

AIM: To determine the impact of different characteristics on postoperative outcomes for patients in a joint arthroplasty Perioperative Surgical Home (PSH) program. METHODS: A retrospective review was performed for patients enrolled in a joint arthroplasty PSH program who had undergone primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients were preoperatively stratified based on specific procedure performed, age, gender, body mass index (BMI), American Society of Anesthesiologists Physical Classification System (ASA) score, and Charleston Comorbidity Index (CCI) score. The primary outcome criterion was hospital length of stay (LOS). Secondary criteria including operative room (OR) duration, transfusion rate, Post-Anesthesia Care Unit (PACU) stay, readmission rate, post-operative complications, and discharge disposition. For each outcome, the predictor variables were entered into a generalized linear model with appropriate response and assessed for predictive relationship to the dependent variable. Significance level was set to 0.05. RESULTS: A total of 337 patients, 200 in the TKA cohort and 137 in the THA cohort, were eligible for the study. Nearly two-third of patients were female. Patient age averaged 64 years and preoperative BMI averaged 29 kg/m(2). The majority of patients were ASA score III and CCI score 0. After analysis, ASA score was the only variable predictive for LOS (P = 0.0011) and each increase in ASA score above 2 increased LOS by approximately 0.5 d. ASA score was also the only variable predictive for readmission rate (P = 0.0332). BMI was the only variable predictive for PACU duration (P = 0.0136). Specific procedure performed, age, gender, and CCI score were not predictive for any of the outcome criteria. OR duration, transfusion rate, post-operative complications or discharge disposition were not significantly associated with any of the predictor variables. CONCLUSION: The joint arthroplasty PSH model reduces postoperative outcome variability for patients with different preoperative characteristics and medical comorbidities.

OBJECTIVES: To create and evaluate normalized T1rho profiles of the entire femoral cartilage in healthy subjects with three-dimensional (3D) angle- and depth-dependent analysis. METHODS: T1rho images of the knee from 20 healthy volunteers were acquired on a 3.0-T unit. Cartilage segmentation of the entire femur was performed slice-by-slice by a board-certified radiologist. The T1rho depth/angle-dependent profile was investigated by partitioning cartilage into superficial and deep layers, and angular segmentation in increments of 4 degrees over the length of segmented cartilage. Average T1rho values were calculated with normalized T1rho profiles. Surface maps and 3D graphs were created. RESULTS: T1rho profiles have regional and depth variations, with no significant magic angle effect. Average T1rho values in the superficial layer of the femoral cartilage were higher than those in the deep layer in most locations (p < 0.05). T1rho values in the deep layer of the weight-bearing portions of the medial and lateral condyles were lower than those of the corresponding non-weight-bearing portions (p < 0.05). Surface maps and 3D graphs demonstrated that cartilage T1rho values were not homogeneous over the entire femur. CONCLUSIONS: Normalized T1rho profiles from the entire femoral cartilage will be useful for diagnosing local or early T1rho abnormalities and osteoarthritis in clinical applications. KEY POINTS: * T1rho profiles are not homogeneous over the entire femur. * There is angle- and depth-dependent variation in T1rho profiles. * There is no influence of magic angle effect on T1rho profiles. * Maps/graphs might be useful if several difficulties are solved.

INTRODUCTION: The demand for total knee arthroplasty (TKA) continues to challenge hospital financial resources. Hospitals have countered this economic demand by reducing patient length of stay (LoS), thus requiring a higher utilization of extended care facilities (ECF) and home with home health care (HHC). With an increase in the number of insured low-income families following the Affordable Care Act (ACA), TKA patients' demographics are anticipated to change. Both trends have significant economic implications, and predicting the discharge destinations of TKA patients would help plan for future health expenditures. The purpose of this study was to determine which variables are significant in predicting discharge destinations of patients treated with TKA. METHODS: We utilized the California Hospital Discharge data set of the year 2010. For each hospitalization, the data set includes information about patient demographics (age, gender, race, and ethnicity), insurance type, diagnoses and procedures, and patient disposition. Discharge to home was the reference category. Discharges to a skilled nursing home and discharge to home with home care were the 2 additional alternatives. Independent variables included the Charlson comorbidity index, payer category (private, Medicare, Medical, and other), race, ethnicity, age, and gender. RESULTS: Over 28 611 TKAs were reviewed with 45.9% discharged to HHC, 29.9% going to ECF, and 24.2% going home without home health care. Race, age, insurance, and morbidity proved to be highly significant factors influencing patient discharge destination (P < .001). Medicare coverage relative to private payers was a strong predictor for discharge destination (relative risk ratio (RRR) 1.69, P < .001). The strongest predictors were black and Asian races relative to whites (RRR 1.54, P < .01). Male gender was the only factor that lowered the risk of discharge to a nursing home (RRR 0.43, P < .001). CONCLUSIONS: This study provides insight on which patient characteristics influence discharge destination after TKA. Race, age, insurance, and morbidity were highly significant (P < .001) factors on patient discharge destination.

BACKGROUND: Although total knee arthroplasty (TKA) is associated with improved patient-reported function, pain, and quality of life, the effects on weight loss are less certain. In this study, we use data from a large, prospective cohort study of osteoarthritis (OA) patients to compare the changes in body mass index (BMI) across 6 years in OA patients who received TKA compared with OA patients who did not receive TKA. METHODS: Using data from the Osteoarthritis Initiative, a prospective cohort study of patients with OA, our study divided patients into two groups: patients who received a TKA during the Osteoarthritis Initiative study (N = 140) and those who did not (N = 697). The initial BMI, final BMI, and change in weight over 72 months were compared between groups. Subgroup analysis was performed by dividing patients by their initial BMI, gender, and age. RESULTS: The TKA group's change in weight, initial BMI, and final BMI were not significantly different from the non-TKA group over 72 months (weight change: -0.763 kg vs +0.191 kg; P = .597). Subgroups of women and patients aged 51-60 years with TKA gained more weight than respective non-TKA OA patients. CONCLUSIONS: Overall, patients who received TKA did not lose or gain more weight than OA patients who did not receive TKA. Patients with longer follow-up after TKA (>2 years) still gained weight on average. Despite the improved patient-reported pain levels, function, and quality of life after TKA, it appears that TKA alone is not a sufficient intervention for obesity.

The ratio of anteroposterior (AP) to medial-lateral (ML) dimensions of the distal femur in adults differs by sex. The average AP/ML dimension ratios are 0.82 for females and 0.79 for males. How and when this difference develops is not yet understood. In this study, the distal femoral dimensions and physeal development of 345 participants younger than 21 years of age were evaluated by MRI. Regression analysis indicated a significant increase in the AP/ML ratio with increasing age for both sexes. In girls, the ratio increased from 0.63 at ages 0-5 years to 0.76 at 15-20 years. In boys, the ratio increased from 0.61 to 0.73 over the same age groups. Female distal femur dimensions are narrower than that of males from birth. Throughout childhood, both sexes show gradual increases in AP/ML ratios. After closure of the physes, the AP/ML ratio in children approaches adult values, with females continuing to have relatively narrower dimensions than males.

INTRODUCTION: Proper ligament tension in flexion with posterior cruciate retaining (CR) total knee arthroplasty (TKA) has long been associated with clinical success. The purpose of this study was to determine the effect of varying levels of posterior cruciate ligament (PCL) release on the tibiofemoral kinematics and PCL strain. MATERIALS AND METHODS: A computational analysis was performed and varying levels of PCL release were simulated. Tibiofemoral kinematics was evaluated. The maximum PCL strain was determined for each bundle to evaluate the risk of rupture based on the failure strain. RESULTS: The femoral AP position shifted anteriorly as the PCL stiffness was reduced. PCL strain in both bundles increased as stiffness was reduced. The model predicts that the AL bundle should not rupture for a 75% release. Risk of PM bundle rupture is greater than AL bundle. DISCUSSION: Our findings suggest that a partial PCL release impacts tibiofemoral kinematics and ligament tension and strain. The relationship is dynamic and care should be taken when seeking optimal balance intra-operatively.

The potential for using mobile applications (apps) as an effective tool to monitor patients in an outpatient setting is promising. Past studies have investigated the use of applications in preoperative and postoperative settings as well as in monitoring and treating chronic illnesses such as diabetes, congestive heart failure (CHF), and multiple sclerosis. However, there is limited data on its specific use in the context of total knee arthroplasty. Given the complicated nature and crucial role of patient adherence to protocols during the preparatory and recovery phases of the procedure, the use of an app can serve as a helpful tool in aiding patients throughout this process. We present a pilot study to assess the efficacy of using such an app in order to monitor patient adherence to total knee arthroplasty-specific preoperative and postoperative protocols. Preoperative protocols used in this study included a 5-item medication protocol and multiple activity instructions. Postoperative patient protocols included following instructions on topics such as recording responses to quality-of-life questions, when and how to contact the clinical team if patients had non-emergent concerns or questions, and carrying out daily physical therapy (PT) exercises. Patients received and recorded responses to these preoperative and postoperative instructions using the iGetBetter program application installed on an iPad Mini, provided to the participants. Patient adherence was based on the data gathered from the patient responses inputted on this app. Adherence rates were comparable to those reported in various past studies that also investigated rates of adherence to health management-related instructions communicated through mobile apps.