Faculty Bibliography

BACKGROUND: Expenditures for postacute care in total joint arthroplasty (TJA) have risen dramatically over recent decades. Therefore, efforts are underway to better identify cost savings in postacute rehabilitation centers, such as skilled nursing facilities (SNFs). The primary purpose of this study was to analyze gait training achievements in post-TJA patients in the interval between hospital discharge and the patients' first 4 days at the SNF. Identification of potential losses in therapeutic progress may lead the way for improved patient care, outcomes, and cost savings. Our hypothesis is that patients discharged to an SNF will have a decline in gait achievements upon transfer from the hospital. METHODS: A total of 68 patients who underwent TJA were included. The total distance ambulated during physical therapy (PT) was recorded for the last day of hospital therapy and the first 4 days at the SNF as well as the reported visual analog scale (VAS) pain scores. RESULTS: There was a 73% decline in distance ambulated on SNF day 0 (Hospital: 138.6 ft vs SNF: 37.9 ft; P < .001) and a 50% decline on SNF day 1 (Hospital: 103.0 ft; SNF vs 51.1 ft; P < .001) compared to the last hospital session. There were no significant differences in distance walked on SNF days 3 and 4 relative to the last hospital session. The VAS pain scores did not significantly differ on SNF days 0 and 1 compared to the last hospital day but began to significantly decline on SNF day 3 (Hospital: 4.9; SNF: 3.3; P = .02) and day 4 (Hospital: 3.9; SNF: 2.3; P = .03). CONCLUSION: There was a significant decline in ambulatory proficiency in post-TJA patients on the day of and the day following hospital discharge to an SNF. These deficits cannot be attributed to heightened pain levels. Early and progressive ambulation is a recognized component of appropriate PT following TJA. This study therefore highlights the transition from hospital to SNF as a crucial and novel target for improvement in post-TJA care.

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.

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.

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.

BACKGROUND: With increasing health care expenditures, reform has largely focused on cost containment, particularly in elective procedures such as total hip and knee arthroplasty (THA and TKA, respectively). The primary objective of this study is to determine what financial value patients place on these highly successful procedures. METHODS: An anonymous survey was administered to 670 patients at 4 different institutions (2 private practice and 2 academic centers) in the outpatient setting over a 15-month period. Patients were asked what reimbursement a surgeon should receive for a primary total joint arthroplasty (TJA), their perception of how much Medicare actually reimburses for TJA, how much they would pay out of pocket for the procedure, and their opinion of current Medicare reimbursement rates. RESULTS: Of the 557 patients who participated in the survey (83% response rate), patients on average felt that orthopedic surgeons should be reimbursed $27,430 for a THA and $19,830 for a TKA. Patients would be willing to pay a significant amount of out-of-pocket costs for their procedure, mean of $14,397 for THA (50.3% of total costs) and $12,797 for TKA (46.3% of total costs). Although patients in private practice groups had higher education and household income (P < .001), patients in academic centers would be willing to pay more out-of-pocket costs ($15,922 vs $5782, P = .034 for THA, $14,419 vs $4556, P = .052 for TKA). CONCLUSION: Patients in both private practice and academic centers feel that surgeons are underpaid for primary THA and TKA. As controversy continues to surround orthopedic surgeons' participation in Medicare, many patients are still willing to pay a significant amount of out-of-pocket expenses for TJA.

INTRODUCTION: The clinical relevance of limb length discrepancy (LLD) after total hip arthroplasty gains attention as the number of total hip arthroplasties increases. Although several techniques are commonly used to assess LLD using a pelvic radiograph, their accuracy is not well established. This study measures LLD using different techniques viewing the pelvis and compares the measurements with the true LLD. METHOD: Pelvic landmarks used included the femoral head, lesser trochanter, acetabular teardrop, ischial tuberosity, and tibial plafond. The true LLD was determined by finding the difference in distance between the lowest point of the ischial tuberosity and the tibial plafond as well as the top of the femoral head to the center of the tibial plafond for each lower limb. RESULTS: Using pelvic landmarks to assess LLD is significantly different (P < .001) from the true LLD. The difference in distance from the center of the tibial plafond to the ischial tuberosity was not significantly different from the measurement from the top of the femoral head to the center of the tibial plafond (P = .08). Also, using the acetabular teardrop as a landmark has less reliability when compared to the ischial tuberosity. DISCUSSION: Owing to the extensive variety of pathologies that are associated with LLD, preoperative planning should include an assessment of any preexisting LLD. Although it may be reasonable to compare pelvic measurements preoperatively and postoperatively to assess for changes, the data from this study do not support the estimation of the true LLD using a pelvic radiograph.

Total hip arthroplasty (THA) is an increasingly common procedure among elderly individuals. Although conversion THA is currently bundled in a diagnosis related group (DRG) with primary THA, no study has identified whether conversion THA better resembles a primary or revision THA. The American College of Surgeons National Surgical Quality Improvement Project database was queried to identify 2009 conversion THA, 67,854 primary THA, and 5,089 revision THA procedures between 2009 and 2014. Univariate analysis was used to compare fifty-three preoperative, intraoperative, and postoperative variables. Seventeen variables demonstrated a statistical difference between conversion and primary THA without a corresponding difference between conversion and revision THA. Only one variable demonstrated a difference between conversion and revision THA without a similar difference between conversion and primary THA. This imbalance suggests that conversion THA better resembles revision THA characteristics, and that these procedures should be reclassified in the same DRG as revision THA instead of primary THA.

BACKGROUND: Effective use of prophylactic antibiotics decreases the incidence of surgical site infections (SSIs) after total joint arthroplasty (TJA). The purpose of this prospective study was to determine the viability of weight-based dosing protocols for cefazolin and vancomycin to determine if appropriate minimum inhibitory concentrations (MIC) are met. METHODS: Trabecular bone was harvested from discarded bone samples from 34 patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA). The cefazolin and vancomycin concentrations were determined in the trabecular bone using high-performance liquid chromatography. RESULTS: No difference was noted in bone concentration with respect to patient weight for cefazolin. Regarding vancomycin, a substantial difference was noted in trabecular bone concentrations with respect to patient weight with lower body mass index (BMI) achieving greater concentrations. Using the current weight-based protocol of antibiotic prophylaxis, 84% and 87% of patients receiving vancomycin and cefazolin, respectively, achieved bone concentrations above the MIC. CONCLUSIONS: Our assessment of trabecular concentration of cefazolin during TJA did not show any differences with respect to patient weight. However, vancomycin concentrations did show a difference with respect to BMI but this may be the result of the specific weight-based dosing protocol of vancomycin. Whereas the majority of cases were able to achieve adequate antibiotic concentrations in bone, further studies may be required to determine if increasing the pre-operative dosage of antibiotics is mandated given the findings of this pilot study.

INTRODUCTION: Increasing hip fracture incidence in the United States is leading to higher occurrences of conversion total hip arthroplasty (THA) for failed surgical treatment of the hip. In spite of studies showing higher complication rates in conversion THA, the Centers for Medicare and Medicaid services currently bundles conversion and primary THA under the same diagnosis-related group. We examined the cost of treatment of conversion THA compared with primary THA. Our hypothesis is that conversion THA will have higher cost and resource use than primary THA. METHODS: Fifty-one consecutive conversion THA patients (Current Procedure Terminology code 27132) and 105 matched primary THA patients (Current Procedure Terminology code 27130) were included in this study. The natural log-transformed costs for conversion and primary THA were compared using regression analysis. Age, gender, body mass index, American Society of Anesthesiologist, Charlson comorbidity score, and smoker status were controlled in the analysis. Conversion THA subgroups formed based on etiology were compared using analysis of variance analysis. RESULTS: Conversion and primary THAs were determined to be significantly different (P<.05) and greater in the following costs: hospital operating direct cost (29.2% greater), hospital operating total cost (28.8% greater), direct hospital cost (24.7% greater), and total hospital cost (26.4% greater). CONCLUSIONS: Based on greater hospital operating direct cost, hospital operating total cost, direct hospital cost, and total hospital cost, conversion THA has significantly greater cost and resource use than primary THA. In order to prevent disincentives for treating these complex surgical patients, reclassification of conversion THA is needed, as they do not fit together with primary THA.

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.