Faculty Bibliography

The purpose of this study was to determine the percentage of patients discharged with a subtherapeutic INR <1.8 using our institutions inpatient warfarin dosing nomogram following total joint arthroplasty (TJA). We examined predisposing risk factors for a subtherapeutic discharge (INR <1.8), including increased body weight, age, gender, end stage renal disease (ESRD), smoking, and peri-operative transfusion. Chart review identified 249 patients for study inclusion. Logistic regression (LR) was used to identify associated risk factors for a subtherapeutic INR (<1.8) on day of discharge. The majority of patients (58.6%, 146 of 249) following TJA surgery were found to have a subtherapeutic INR level (INR<1.8) at discharge (mean length of stay 2.6 days). Multivariate LR analysis found that weight greater than 180 lbs. (OR 2.08, CI 1.09, 3.98, P=0.027) was found to increase the odds of a subtherapeutic INR on day of discharge. Our results were not significant for weight 20% beyond ideal body weight, age (>65y), gender, peri-operative transfusion, smoking, ESRD or autoimmune disease. A patient's body weight influences response to warfarin following TJA. An inpatient warfarin dosing nomogram that takes into account a patient's weight should be used to reduce the risk of subtherapeutic INR levels in obese TJA patients.

AIM: To investigate the postoperative transfusion and complication rates of anemic and nonanemic total joint arthroplasty patients given tranexamic acid (TXA). METHODS: A cross-sectional prospective study was conducted of primary hip and knee arthroplasty cases performed from 11/2012 to 6/2014. Exclusion criteria included revision arthroplasty, bilateral arthroplasty, acute arthroplasty after fracture, and contraindication to TXA. Patients were screened prior to surgery, with anemia was defined as hemoglobin of less than 12 g/dL for females and of less than 13 g/dL for males. Patients were divided into four different groups, based on the type of arthroplasty (total hip or total knee) and hemoglobin status (anemic or nonanemic). Intraoperatively, all patients received 2 g of intravenous TXA during surgery. Postoperatively, allogeneic blood transfusion (ABT) was directed by both clinical symptoms and relative hemoglobin change. Complications were recorded within the first two weeks after surgery and included thromboembolism, infection, and wound breakdown. The differences in transfusion and complication rates, as well as the relative hemoglobin change, were compared between anemic and nonanemic groups. RESULTS: A total of 232 patients undergoing primary joint arthroplasty were included in the study. For the total hip arthroplasty cohort, 21% (18/84) of patients presented with preoperative anemia. Two patients in the anemic group and two patients in the nonanemic group needed ABTs; this was not significantly different (P = 0.20). One patient in the anemic group presented with a deep venous thromboembolism while no patients in the nonanemic group had an acute complication; this was not significantly different (P = 0.21). For nonanemic patients, the average change in hemoglobin was 2.73 +/- 1.17 g/dL. For anemic patients, the average change in hemoglobin was 2.28 +/- 0.96 g/dL. Between the two groups, the hemoglobin difference of 0.45 g/dL was not significant (P = 0.13). For the total knee arthroplasty cohort, 18% (26/148) of patients presented with preoperative anemia. No patients in either group required a blood transfusion or had an acute postoperative complication. For nonanemic patients, the average change in hemoglobin was 1.85 +/- 0.79 g/dL. For anemic patients, the average change in hemoglobin was 1.09 +/- 0.58 g/dL. Between the two groups, the hemoglobin difference of 0.76 g/dL was significant (P < 0.001). CONCLUSION: TXA administration results in low transfusion and complication rates and may be a useful adjunct for TJA patients with preoperative anemia.

The clinical outcome of total knee arthroplasty (TKA) remains suboptimal in some patients. One of the factors that might hinder improved functionality may be postoperative limb length discrepancy due to increase in limb length of the operative limb. The objective of this cross-sectional prospective study was to examine the extent to which limb length change occurs after TKA and to compare the change in limb length to the degree of valgus or varus joint position preoperatively. The role of body mass index and Kellgren-Lawrence grade in limb length change was also assessed. The data of 137 TKAs were analyzed and separated into categories to compare change in limb length pre- versus postoperatively. In all, 59.1% of patients experienced an increase in limb length with an average increase of 0.438 cm, but overall, there was no statistically significant difference in limb length pre- versus postoperatively (P value 0.598). Similar trends were seen within all other groups. It is the conclusion of this study that limb lengthening after TKA does not frequently occur to a statistically significant extent, regardless of preoperative joint state.

PURPOSE: To investigate the difference in T1rho profiles of the entire femoral cartilage between SPGR and b-FFE sequences at 3.0T. MATERIALS AND METHODS: 20 healthy volunteers were enrolled in this study. T1rho images of each subject were acquired with two types of pulse sequences: SPGR and b-FFE. Femoral cartilage segmentation was performed by two independent raters slice-by-slice using Matlab. Inter- and intra-observer reproducibility between the two imaging protocols was calculated. The relative signal intensity (SI) of cartilage, subchondral bone marrow, joint effusion, and the relative signal contrast between structures of the knee were quantitatively measured. The difference in T1rho values between SPGR and b-FFE sequences was statistically analyzed using the Wilcoxon signed-rank test. RESULTS: The average T1rho value of the entire femoral cartilage with b-FFE was significantly higher compared to SPGR (p<0.05). The reproducibility of the segmented area and T1rho values was superior with SPGR compared to b-FFE. The inter-class correlation coefficient was 0.846 on SPGR and 0.824 on b-FFE. The intra-class correlation coefficient of T1rho values was 0.878 on SPGR and 0.836 on b-FFE. The two imaging techniques demonstrated different signal and contrast characteristics. The relative SI of fluid was significantly higher on SPGR, while the relative SI of subchondral bone was significantly higher on b-FFE (p<0.001). There were also significant differences in the relative contrast between fluid-cartilage, fluid-subchondral bone, and cartilage-subchondral bone between the two sequences (all p<0.001). CONCLUSION: We need to pay attention to differences in T1rho values between SPGR and b-FFE in clinical applications.

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, there is a lack of literature supporting this classification and it has yet to be identified whether conversion THA better resembles primary or revision THA. This editorial analyzed the intraoperative and postoperative factors and functional outcomes following conversion THA, primary THA, and revision THA to understand whether the characteristics of conversion THA resemble one procedure or the other, or are possibly somewhere in between. The analysis revealed that conversion THA requires more resources both intraoperatively and postoperatively than primary THA. Furthermore, patients undergoing conversion THA present with poorer functional outcomes in the long run. Patients undergoing conversion THA better resemble revision THA patients than primary THA patients. As such, patients undergoing conversion THA should not be likened to patients undergoing primary THA when determining risk stratification and reimbursement rates. Conversion THA procedures should be planned accordingly with proper anticipation of the greater needs both in the operating room, and for in-patient and follow-up care. We suggest that conversion THA be reclassified in the same DRG with revision THA as opposed to primary THA as a step towards better allocation of healthcare resources for conversion hip arthroplasties.

Past studies have shown successful outcomes regarding the use of various interventional education methods in improving patient compliance. At our institution, different educational resources are offered and encouraged, including a 2-hour-long educational class, to prepare patients who are undergoing total joint arthroplasty procedures. Given the significant impact that patient compliance with preoperative instruction can have on overall outcomes of these procedures, this study was intended to assess the effects that the educational classes can have on patient compliance with this institution's 6-point preoperative total joint arthroplasty protocol. The study analyzed 2 groups, those who did and did not attend the preoperative classes, and compliance rates were compared between the 2. It was hypothesized that patients who did attend the classes would be more compliant to the protocol compared to those who did not. Although results from the study showed that there were no significant differences in adherence between the 2 groups, future quality assessment studies can build off this in order to move toward achieving optimal patient compliance with preoperative instructions.

BACKGROUND: Modular metal-backed tibia components allow surgeons intraoperative flexibility. Although it is known that modular tibia components introduce the possibility for backside wear resulting from relative motion between the polyethylene insert and the tibial baseplate, it is not known to what degree variability in the conformity of the tibial polyethylene liner itself might contribute to backside wear. QUESTIONS/PURPOSES: The purpose of this study was to determine whether a flat, cruciate-retaining tibial polyethylene bearing generates less backside wear than a more conforming (curved) tibial polyethylene bearing in an analysis of specimens explanted during revision surgery. METHODS: The study included 70 total knee inserts explanted at revision surgery, all implanted and explanted by the same surgeon. Two different cruciate-retaining insert options in an otherwise similar knee system were used: one with a curved-on-flat (17) articular geometry and one with a highly conforming curved-on-curved design (53); both groups were sequential cohorts. The composite backside wear depth for the insert as well as the volume of backside wear was measured and compared between groups. RESULTS: The median linear backside-normalized wear for the posterior lipped inserts was 0.0063 mm/year (range, 0-0.085 mm/year), which was lower than for the curved inserts at 0.05 mm/year (range, 0.00003-0.14 mm/year) (p<0.001). The median calculated volumetric backside-normalized wear for the posterior lipped inserts was 14.2 mm3/year (range, 0-282.8 mm3/year) compared with 117 mm3/year (range, 2.1-312 mm3/year) for the curved inserts (p<0.001). CONCLUSIONS: In this retrieval study, more conforming tibial inserts demonstrated more backside-normalized wear than the flatter designs. This suggests that in this modular total knee arthroplasty design, higher articular conformity to address the issues of high bearing contact stress comes at a price: increased torque transmitted to the backside insert-to-tray interface. We suggest further work be undertaken to examine newer insert designs to evaluate if our conclusions hold true with the newer generation locking mechanism, tibial tray finish and polyethylene designs, as more highly conforming tibial inserts are introduced into the market. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Total knee arthroplasty (TKA) is associated with improved patient-reported pain levels, function, and quality of life; however, it is poorly understood whether there is increased physical activity following TKA. Using data from the Osteoarthritis Initiative (OAI), we compare physical activity, as measured using an accelerometer, and patient-reported outcome measures of 60 patients who had already received a TKA with 63 patients who eventually received a TKA during the OAI study. There was no significant difference in activity levels between the two groups as measured by the accelerometer. Total WOMAC, KOOS Quality of Life, KOOS Knee Pain, and KOOS Function scores improved in the post-TKA compared to the pre-TKA group. In both pre-TKA and post-TKA groups, physical activity guidelines were met in only 5% or less.

OBJECTIVE: To perform a general literature review of dysbaric osteonecrosis (DON) to describe its pathophysiology, prevalence in scuba divers, prognosis, and treatment options. DATA SOURCES: A literature search on PubMed was performed using the term "dysbaric osteonecrosis" yielding 67 results. There was no exclusion based on dates. Articles that mainly dealt with decompression sickness secondary to tunnel work, mining, or airplane travel were not selected. An additional search on PubMed using the terms "(osteonecrosis diving) NOT dysbaric" was performed to identify other publications not picked up in the initial search. MAIN RESULTS: Dysbaric osteonecrosis is associated with prolonged hyperbaric exposure and rapid decompression that cause nitrogen bubbles to enter the fatty marrow-containing shafts of long bones leading to reduction in blood flow and subsequent osteonecrosis. Patients may present asymptomatically, and typical radiographic findings of DON include: decalcification of bone, cystic lesions, osteosclerotic patterns, nontraumatic fractures, bone islands, and a subchondral crescent sign. Surgical treatment options are comprised of core decompression and free vascularized fibular graft, whereas nonsurgical treatment options consist of monitoring, physical therapy, and bisphosphonate therapy. CONCLUSIONS: Although the incidence of DON has decreased significantly over the past 2 decades, the lack of timely diagnosis and optimal management keeps DON relevant in the orthopedic and sport medicine community.

INTRODUCTION: With this growing demand, the length of stay for total hip arthroplasty (THA) procedures has decreased, and as a trade-off, we have seen a higher utilization of extended care facilities (ECFs). Both trends have significant economic implications on the health care system, and predicting the discharge destinations of THA patients would help policy makers plan for future health expenditures. We performed a retrospective data analysis of a large patient database to determine which variables are significant in predicting discharge destinations of THA patients. METHODS: We used the California Hospital Discharge data set of the year 2010, collected and provided by the Office of Statewide Health Planning and Development. The data set includes information about patient demographics, insurance type, diagnoses and procedures, and patient disposition. The study cohort included 14 326 patients. Discharge to home was the reference category. Discharge to ECF and discharge to home with home care were the 2 additional alternatives. RESULTS: In all, 46.9% of patients were discharged home with home health care, followed by 29.6% to ECF, and 23.5% to home without care. Discharge to ECF was more likely for patients with more comorbidities and a higher age. The strongest predictors were Medicaid and black or Asian race. Medicare relative to private payer was a strong predictor of ECF discharge. Male gender was the only factor that lowered the risk of discharge to ECF. The strongest predictor for discharge to home with home care was black race relative to whites. Medicaid lowered the risk of home care, and gender did not matter. CONCLUSION: This study serves to provide insight on which patient characteristics influence discharge destination after THA. Race, insurance, and morbidity were highly significant factors on patient discharge destination to a subacute nursing facility.