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1.  [No title available] 
PMCID: PMC3784630  PMID: 23764034
2.  [No title available] 
PMCID: PMC4049456  PMID: 23786986
3.  [No title available] 
PMCID: PMC4096551  PMID: 23856062
4.  Cerebrovascular Disease Is Associated with Outcomes after Total Knee Arthroplasty: A U.S. Total Joint Registry Study 
The Journal of arthroplasty  2013;29(1):10.1016/j.arth.2013.04.003.
We assessed the association of cerebrovascular disease with patient-reported outcomes (PROs) of moderate-severe activity limitation and moderate-severe pain at 2- and 5-years after primary total knee arthroplasty (TKA) using multivariable-adjusted logistic regression. 7,139 primary and 4,234 revision TKAs were included. Compared to the patients without cerebrovascular disease, those with cerebrovascular disease had a higher odds ratio (OR) of moderate-severe limitation at 2-years and 5-years, 1.32 (95% confidence interval [CI]: 1.02, 1.72; P=0.04) and 1.83 (95% CI: 1.32, 2.55; P<0.001). No significant associations were noted with moderate-severe pain at 2-years or 5-years. In conclusion, we found that cerebrovascular disease is independently associated with pain and function outcomes after primary TKA. This should be taken into consideration when discussing expected outcomes of TKA with patients.
PMCID: PMC3783649  PMID: 23664282
Pain; Activity limitation; cerebrovascular disease; Total knee replacement; arthroplasty; joint replacement; outcomes; Patient-Reported Outcomes; Activities of Daily Living; ADLs; Function; functional limitation
5.  Variation of Medicare payments for total knee arthroplasty 
The Journal of arthroplasty  2013;28(9):1513-1520.
We analyzed the 2009 Medicare inpatient claims data and other databases to estimate Medicare payments for primary or revision total knee arthroplasty (TKA). The average Medicare hospital payment per procedure was $13464 for primary TKA (n=227587) and $17331 for revision TKA (n=18677). For both primary and revision TKA Medicare payments varied substantially across patients, hospitals and healthcare markets. Less than one percent of primary TKA cases but seven percent of revision TKA cases triggered Medicare “outlier” payments, which were $10000 or higher per case beyond regular diagnosis-related-group payments. Urban and major teaching hospitals were more likely to treat these unusually expensive cases. Hospitals in the Northeast and West regions tended to receive higher Medicare payments than hospitals in the Midwest.
PMCID: PMC3795823  PMID: 23845765
total knee arthroplasty; Medicare; payment; outlier payment; revision TKA
6.  Topical tranexamic acid reduces blood loss and transfusion rates in total hip and total knee arthroplasty 
The Journal of arthroplasty  2013;28(9):10.1016/j.arth.2013.06.011.
The objective of this study was to determine if tranexamic acid (TXA) applied topically reduced postoperative bleeding and transfusion rates after primary total hip arthroplasty (THA) and primary total knee arthroplasty (TKA).
Two hundred and ninety consecutive patients from a single surgeon were enrolled. In TKA, TXA solution was injected into the knee after closure of the arthrotomy. In THA, the joint was bathed in TXA solution at three points during the procedure. In both THA and TKA the TXA solution was at a concentration of 3gm TXA per 100mL saline.
The mean blood loss was significantly higher in the non-TXA patients in both TKA and THA groups. Postoperative transfusions decreased dramatically with TXA, dropping from 10% to 0%, and from 15% to 1%, in the TKA and THA groups, respectively.
Topical application of TXA significantly reduces postoperative blood loss and transfusion risk in TKA and THA.
PMCID: PMC3807723  PMID: 23886406
Blood Transfusion; Tranexamic Acid; Antifibrinolytic; Total Knee Arthroplasty; Total Hip Arthroplasty
7.  Bariatric Surgery Prior to Total Joint Arthroplasty May Not Provide Dramatic Improvements In Post Arthroplasty Surgical Outcomes 
The Journal of arthroplasty  2014;29(7):1359-1364.
This study compared the total joint arthroplasty (TJA) surgical outcomes of patients who had bariatric surgery prior to TJA to TJA patients who were candidates but did not have bariatric surgery. Patients were retrospectively grouped into: Group 1 (n=69), those with bariatric surgery >2 years prior to TJA, Group 2 (n=102), those with surgery within 2 years of TJA, and Group 3 (n=11,032), those without bariatric surgery. In Group 1, 2.9% (95%CI 0.0–6.9%) had complications within 1 year compared to 5.9% (95%CI 1.3–10.4%) in Group 2, and 4.1% (95%CI 3.8–4.5%) in Group 3. 90-day readmission (7.2%, 95%CI 1.1–13.4%) and revision density (3.4/100 years of observation) was highest in Group 1. Bariatric surgery prior to TJA may not provide dramatic improvements in post-operative TJA surgical outcomes.
PMCID: PMC4151515  PMID: 24674730
bariatric surgery; joint arthroplasty; obesity; revision; surgical site infection; complications
8.  Does Aspirin Have a Role in Venous Thromboembolism Prophylaxis in Total Knee Arthroplasty Patients? 
The Journal of arthroplasty  2009;25(7):1053-1060.
The objectives of this study were to compare the risk of venous thromboembolism (VTE), bleeding, surgical site infection, and mortality in patients receiving aspirin or guideline-approved VTE prophylactic therapies (warfarin, low-molecular weight heparins, synthetic pentasaccharides) in total knee arthroplasty (TKA). We analyzed clinical and administrative data from 93,840 patients who underwent primary TKA at 307 U.S. hospitals over a 24 month period. 51,923 (55%) patients received warfarin, 37,198 (40%) received injectable agents, and 4,719 (5%) received aspirin. After adjustment for patient and hospital factors, patients who received aspirin VTEP had lower odds for thromboembolism compared to warfarin patients, but similar odds compared to injectable VTEP; there were no differences in risk of bleeding, infection or mortality after adjustment. Our results suggest that aspirin, when used in conjunction with other clinical care protocols, may be effective VTEP for certain TKA patients.
PMCID: PMC4142798  PMID: 19679434
9.  Optimal Irrigation and Debridement of Infected Joint Implants 
The Journal of arthroplasty  2011;26(6 0):109-113.
Acute postoperative and acute, late hematogenous prosthetic joint infections have been treated with 1-stage irrigation and debridement with polyethylene exchange. Success rates, however, are highly variable. Reported studies demonstrate that detergents are effective at decreasing bacterial colony counts on orthopedic implants. Our hypothesis is that the combination of a detergent and an antiseptic would be more effective than using a detergent alone to decrease colony counts from a methicillin-resistant Staphylococcus aureus biofilm-coated titanium alloy disk simulating an orthopedic implant. In our study of various agents tested, chlorhexidine gluconate scrub (antiseptic and detergent) was the most effective at decreasing bacterial colony counts both prereincubation and postreincubation of the disks; pulse lavage and scrubbing were not more effective than pulse lavage alone.
PMCID: PMC4084912  PMID: 21641757
joint infection; debridement; optimal irrigation; MRSA; biofilm
10.  Bone Ingrowth in Well-Fixed Retrieved Porous Tantalum Implants 
The Journal of arthroplasty  2013;28(6):922-927.
While first generation porous coatings have had clinical success, aseptic loosening remains a leading cause of revision. The purpose of this study was to investigate the reason for revision and to assess the amount of bone ingrowth in retrieved porous tantalum components. In a prospective multicenter retrieval program, 76 porous tantalum acetabular shells, 5 femoral stems, 7 patellas and 36 tibial trays were collected from revision surgeries. A subset of the implants were analyzed for bone ingrowth. The main reason for revision was infection for acetabular shells (1.4 year implantation time) and instability for tibial trays (1.8 years implantation time). Two of the thirty primary surgery acetabular shells and one of the thirty-six primary surgery tibial trays were revised for implant loosening. We observed full depth penetration of bone into the porous tantalum layer for the acetabular shells and femoral stems.
PMCID: PMC3664095  PMID: 23518432
11.  Low Vitamin D Status Does Not Adversely Affect Short-term Functional Outcome After Total Hip Arthroplasty 
The Journal of arthroplasty  2012;28(2):315-322.e2.
We prospectively measured functional performances (WOMAC, SF-36, 2-minute walk test and timed get-up-and-go test) of patients who underwent total hip arthroplasty (THA) and had serum vitamin D levels tested during the preoperative evaluation. Of 219 patients, 102 patients (46.6%) had low vitamin D levels (25-hydroxyvitamin D < 30 ng/mL). Low vitamin D status did not adversely affect short-term function at 6 weeks after THA. In addition, there was no association between serum vitamin D levels and the within-patient changes of scores of each outcome measurement. Since this 6-week period is generally adequate to correct vitamin D deficiency, orthopaedic surgeons can safely perform THA without delay. Nevertheless, because vitamin D deficiency impairs bone quality, patients with low vitamin D levels should be treated once identified.
PMCID: PMC4037853  PMID: 22795877
12.  Total hip arthroplasty in patients 50 years or less: Do we improve activity profiles? 
The Journal of arthroplasty  2013;28(5):872-876.
The primary objective of this study was to use step activity monitoring to quantify activity changes after total hip arthroplasty in patients 50 years or less. Secondly, we investigated whether step activity measurements correlated with the Harris hip and UCLA scores.
We prospectively analyzed 37 patients (age ≤50) treated with primary THA. Patient activity was recorded with a step activity monitor. Harris hip and UCLA scores were analyzed.
Total daily stride counts increased by an average of 30.0%. Increases were noted in the percent of daily time spent at high, moderate and low activity. Increases in daily time spent at high activity moderately correlated with the UCLA activity score but did not correlate with the HHS. Both the UCLA score and the HHS did not correlate with mean daily strides.
Following THA, patients ≤ 50 years of age increase their activity by taking more daily strides and improve their activity profile by spending more time at higher activity. Improvements in step activity moderately correlate with improvements in UCLA scores.
PMCID: PMC3932739  PMID: 23499406
Total hip arthroplasty; step activity monitor; activity
13.  Is Increased Modularity Associated With Increased Fretting and Corrosion Damage in Metal-On-Metal Total Hip Arthroplasty Devices? 
The Journal of arthroplasty  2013;28(8 0):2-6.
This retrieval study documents taper damage at modular interfaces in retrieved MOM THA systems and investigates if increased modularity is associated with increased fretting and corrosion. One hundred thirty-four (134) heads and 60 stems (41 modular necks) of 8 different bearing designs (5 manufacturers) were analyzed. Damage at the shell–liner interface of 18 modular CoCr acetabular liners and the corresponding 11 acetabular shells was also evaluated. The results of this study support the hypothesis that fretting and corrosion damage occurs at a variety of modular component interfaces in contemporary MOM THAs. We also found that modularity of the femoral stem was associated with increased damage at the head. An analysis of component and patient variables revealed that dissimilar alloy pairing, larger head sizes, increased medio-lateral offsets and longer neck moment arms were all associated with increased taper damage at the modular interfaces.
PMCID: PMC3971476  PMID: 23910820
total hip arthroplasty; modularity; fretting; corrosion; metal on metal
The Journal of arthroplasty  2013;28(3):543.e9-543.e12.
Damage to metallic bearing surfaces typically involves scratches, scrapes, metal transfer, and organic deposits. This damage can cause accelerated wear of the opposing surface and subsequent implant failure. Photography and viewing of metallic bearing surfaces, for documenting this damage, is hindered by optical reflectivity. This note demonstrates a simple, practical technique for metallic bearing surface photography and viewing that minimizes this reflectivity problem, that does not involve any modification of the bearing surface, and that allows for improved observation and documentation of overall damage. When the metallic bearing surface is placed within a tube of translucent material, the appearance of damage on that bearing surface is dramatically enhanced, showing up against a smooth, even background with excellent contrast and with fine detail achievable.
PMCID: PMC3581706  PMID: 23333257
Arthroplasty; bearing surface; damage; photography; retrieval; wear
15.  Predictors of Moderate-Severe Functional Limitation 2- and 5-years After Revision Total Knee Arthroplasty 
The Journal of arthroplasty  2010;25(7):1091-1095.e4.
In patients who underwent revision TKA from 1993–2005 and responded to follow-up questionnaires 2- or 5-years post-revision TKA, we studied whether body mass index (BMI), comorbidity (measured by validated Deyo-Charlson index), gender and age predict activity limitation 2- and 5-years after Revision TKA. Overall moderate-severe activity limitation was defined as ≥2 activities (walking, stairs, rising chair) with moderate-severe limitation. Multivariable logistic regressions also adjusted for income, diagnosis, distance from medical center and American Society of Anesthesiologists Physical Status (ASA) score. The prevalence of overall moderate-severe activity limitation was high: 46.5% (677/1,456) at 2-years and 50.5% (420/832) at 5-years post-revision TKA. At both 2- and 5-year follow-up, BMI≥40, higher Deyo-Charlson score, female gender and age>80, each significantly predicted higher odds of moderate-severe overall activity limitation.
PMCID: PMC3895366  PMID: 20888546
Revision Total Knee Arthroplasty; Activity Limitation; Functional limitation; predictors; body mass index; age; gender; comorbidity
16.  Are Gender, Comorbidity and Obesity Risk factors for Postoperative Periprosthetic Fractures Following Primary Total Hip Replacement? 
The Journal of arthroplasty  2012;28(1):126-131.e2.
We studied the frequency and patient risk factors for postoperative periprosthetic fractures after primary total hip replacement (THR). With a mean follow-up of 6.3 years, 305 postoperative periprosthetic fractures occurred in 14,065 primary THRs. In multivariable-adjusted Cox regression analyses, female gender (Hazard ratio [HR], 1.48;95% confidence interval [CI]:1.17–1.88), Deyo-Charlson comorbidity score of 2 (HR, 1.74 for score of 2;95% CI: 1.25–2.43) or 3 or higher (HR, 1.71;95% CI: 1.26–2.32), ASA class of 2 (HR, 1.84;95% CI: 0.90–3.76), 3 (HR, 2.45;95% CI: 1.18–5.1) or 4 or higher (HR, 2.68;95% CI: 0.70–10.28) were significantly associated with higher risk/hazard and cemented implant with lower hazard (HR, 0.68; 95% CI: 0.54–0.87) of postoperative periprosthetic fractures. Interventions targeted at optimizing comorbidity management may decrease postoperative fractures after THR.
PMCID: PMC3414633  PMID: 22552223
17.  Minimally Invasive Total Knee Arthroplasty Improves Early Knee Strength but Not Functional Performance: A Randomized Controlled Trial 
The Journal of arthroplasty  2012;27(10):1812-1819.e2.
A prospective, randomized investigation compared early clinical outcomes of total knee arthroplasty (TKA) using conventional (CONTROL) or minimally invasive surgical (MIS) approaches (n=44). Outcome measures included isometric quadriceps and hamstrings strength, quadriceps activation, functional performance, knee pain, active knee range of motion (AROM), muscle mass, the SF-36, and WOMAC, assessed preoperatively and 4 and 12 weeks after TKA. Four weeks after TKA, the MIS group had greater hamstring strength (p=0.02) and quadriceps strength (p=0.07), which did not translate to differences in other outcomes. At 12 weeks, there were no clinically meaningful differences between groups on any measure. Although MIS may lead to faster recovery of strength in patients undergoing TKA, there was no benefit on longer-term recovery of strength or functional performance.
PMCID: PMC3413785  PMID: 22459124
total knee arthroplasty; joint arthroplasty; quadriceps; muscle strength; minimally invasive surgery
18.  Preclinical Evaluation of a Novel Implant for Treatment of a Full-Thickness Distal Femoral Focal Cartilage Defect 
The Journal of arthroplasty  2013;28(8):10.1016/j.arth.2012.11.020.
A novel, nonresorbable, monolithic composite structure ceramic, developed using a partially stabilized zirconia ceramic common to implantable devices, was used in a cementless weight-bearing articular implant to test the feasibility of replacing a region of degenerated or damaged articular cartilage in the knee as part of a preclinical study using male mongrel dogs lasting up to 24 weeks. Gross/histological cartilage observations showed no differences among control, 12-week and 24-week groups, while pull-out tests showed an increase in maximum pull-out load over time relative to controls. Hence, the use of a novel ceramic implant as a replacement for a focal cartilage defect leads to effective implant fixation within 12 weeks and does not cause significant degradation in opposing articular cartilage in the time frame evaluated.
PMCID: PMC3844131  PMID: 23523501
unicondylar hemiarthroplasty; ceramic device; preclinical study; cartilage wear; animal model
19.  Total Knee Arthroplasty in Morbidly Obese Patients Treated with Bariatric Surgery: A Comparative Study 
The Journal of arthroplasty  2012;27(9):1696-1700.
Our objective was to compare outcomes (anesthesia time, total operative time, tourniquet time, duration of hospital stay, 90-day complication rate and transfusion rates) of patients with total knee arthroplasty (TKA) who underwent bariatric surgery before or after TKA. One-hundred-twenty-five patients were included: TKA before bariatric surgery (group 1; n=39); TKA within two years of bariatric surgery (group 2; n=25); and TKA more than 2 years after bariatric surgery (group 3; n=61). Patients with TKA more than 2 years after bariatric surgery had shorter anesthesia, total operative and tourniquet times than other groups; differences were significant between groups. Ninety-day complication and transfusion rates approached but did not meet statistical significance. Ninety-day complication rates and duration of hospital stay did not differ significantly between the three groups.
PMCID: PMC3413743  PMID: 22554730
Total knee arthroplasty; morbidly obese; bariatric surgery; outcomes
20.  Unicompartmental Knee Arthroplasty Enables Near Normal Gait at Higher Speeds, Unlike Total Knee Arthroplasty 
The Journal of Arthroplasty  2013;28(9):176-178.
Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched for age, gender, height and weight and radiological severity were recruited based on high functional scores, more than twelve months post UKA or TKA. These were compared with 14 preop patients and 14 normal controls. Their gait was measured at increasing speeds on a treadmill instrumented with force plates. Both arthroplasty groups were significantly faster than the preop OA group. TKA patients walked substantially faster than any previously reported series of knee arthroplasties. UKA patients walked 10% faster than TKA, although not as fast as the normal controls. Stride length was 5% greater and stance time 7% shorter following UKA — both much closer to normal than TKA. Unlike TKA, UKA enables a near normal gait one year after surgery.
PMCID: PMC3809509  PMID: 24099573
gait; walking speed; stride length; unicompartmental knee arthroplasty; total knee arthroplasty
21.  Patient factors Predict Periprosthetic Fractures Following Revision Total Hip Replacement 
The Journal of arthroplasty  2012;27(8):1507-1512.
We assessed important patient risk factors for postoperative periprosthetic fractures after revision total hip replacement (THR) using prospectively collected Institutional Joint Registry data. We used univariate and multivariable-adjusted Cox regression analyses. There were 330 postoperative periprosthetic fractures after 6,281 revision THRs. In multivariable-adjusted analyses, hazard [95% confidence interval] of periprosthetic fracture was higher for: women, 1.66 [1.32, 2.08], p<0.001; higher Deyo-Charlson comorbidity index of 2, 1.46 (1.03, 2.07) and index of 3+, 2.01 (1.48, 2.73), overall p<0.001; and operative diagnosis, especially previous non-union, 5.76 (2.55, 13.02), overall p<0.001. Hazard was lower in 61–70 year old, 0.64 (0.49, 0.84) and 71–80 year old 0.57 (0.43, 0.76), compared to <60 years (overall p<0.0001). Our study identified important modifiable and unmodifiable risk factors for fractures after revision THR.
PMCID: PMC3360118  PMID: 22342128
22.  Ninety-day Mortality in Patients Undergoing Elective Total Hip or Total Knee Arthroplasty 
The Journal of arthroplasty  2012;27(8):1417-1422.e1.
Using an institutional Joint Registry, we studied frequency, trends and predictors of mortality following elective total hip or knee arthroplasty (THA/TKA). Of the 12,727 and 12,484 patients who underwent THA and TKA respectively, all-cause mortality rates at 7-, 30- and 90-days were as follows: THA, 0.1%, 0.2% and 0.5%; TKA 0.1%. 0.2% and 0.4%, respectively. Statistically significant downward time-trend in 90-day mortality was noted after TKA (p=0.02), but not after THA (p=0.41). In multivariable-adjusted analyses of THA patients, older age, higher comorbidity index, and prior cardiac disease were significantly associated with higher 90-day mortality. In TKA patients, older age, male gender, ASA class of 3-4, and higher comorbidity index were associated with higher 90-day all-cause mortality. Optimization of disease management may reduce postoperative mortality after THA/TKA.
PMCID: PMC3413788  PMID: 22554727
23.  Differences of Knee Anthropometry Between Chinese and White Men and Women 
The Journal of arthroplasty  2010;26(1):124-130.
Whether there are differences in knee anthropometry between Asian and white knees remains unclear. Three-dimensional knee models were constructed using computed tomography or magnetic resonance imaging of healthy Chinese and white subjects. The morphologic measurements of the femur included mediolateral, anteroposterior dimensions, and aspect ratio. The tibial measurements included mediolateral, medial/lateral anteroposterior dimension, aspect ratio, and posterior slope of medial/lateral plateau. The results showed that Chinese knees were generally smaller than white knees. In addition, the femoral aspect ratio of Chinese females was significantly smaller than that of white females (1.24 ± 0.04 vs 1.28 ± 0.06). Tibial aspect ratio differences between Chinese and white males (1.82 ± 0.07 vs 1.75 ± 0.11), though significant, were likely a reflection of differences in knee size between races. These racial differences should be considered in the design of total knee arthroplasty prosthesis for Asian population.
PMCID: PMC3740371  PMID: 20149574
knee geometry; total knee arthroplasty; Chinese; Caucasian; male; female
24.  In-Hospital Patient Falls After Total Joint Arthroplasty 
The Journal of arthroplasty  2011;27(6):823-8.e1.
In-hospital falls (IFs) increase morbidity, cost, and may result in litigation. We analyzed the Nationwide Inpatient Sample to quantify the incidence of IFs in patients who underwent hip and knee arthroplasty and to define trends, patient’s demographics, risk factors, complications, and hospital cost. Patients operated on between 1998 and 2007 were identified and grouped depending on the presence of a diagnosis of IF. Of those, 0.85% had an IF, representing 2.1 falls per 1000 inpatient days. The incidence of IF increased from 0.4% to 1.3% during the study period. Independent risk factors included revision surgery, advanced age, male sex, minority race, and the presence of comorbidities. Patients having IF had a longer hospital stay and were less likely to be discharged to their primary residence. In-hospital mortality, complications, and cost were higher in patients sustaining IF. Given the associated morbidity, mortality, and increased cost, resources should be allocated to minimize the risk of IF in this population.
PMCID: PMC3653584  PMID: 22115762
total joint anthroplasty; complications; in-patient falls; safety
The Journal of Arthroplasty  2011;27(5):742-749.
The hypothesis of this study was that acetabular liner vulnerability to scratching from femoral heads, roughened by third bodies embedded in the liner, is not significantly lower for highly crosslinked polyethylene (HXPE) than for conventional polyethylene (CPE). Six CPE and six HXPE acetabular liners were each reproducibly embedded with five CoCrMo beads, then run for 10,000 cycles in a joint simulator. By visual rank-ordering, there was low association between liner scratch severity and polyethylene type. The CPE and HXPE liner scratches were not significantly different in scratch peak-valley height or width, or in liner roughness in the vicinity of the embedded beads. This model indicated that high crosslinking of polyethylene does not offer appreciable protection against severe scratching induced by large embedded third body particles.
PMCID: PMC3290760  PMID: 22115764

Results 1-25 (45)