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1.  Patient-level clinically meaningful improvements in activities of daily living and pain after total hip arthroplasty: data from a large US institutional registry 
Rheumatology (Oxford, England)  2013;52(6):1109-1118.
Objective. To characterize patient-level clinically meaningful improvements in pain and limitation of key activities of daily living (ADLs) after primary or revision total hip arthroplasty (THA).
Methods. We analysed prospectively collected data from the Mayo Clinic Total Joint Registry to study clinically meaningful improvements in index hip pain severity and limitation in seven key ADLs (walking, climbing stairs, putting on shoes/socks, picking up objects, getting in/out of car, rising from a chair and sitting), from preoperative to 2- and 5-year post-THA.
Results. The primary THA cohort consisted of 6168 responders preoperatively, 5707 at 2 years and 3289 at 5 years postoperatively. The revision THA cohort consisted of 2063 responders preoperatively, 2682 at 2 years and 1627 at 5 years postoperatively. In the primary THA cohort, clinically meaningful pain reduction to mild or no hip pain at 2 years was reported by 94% with moderate and 91% with severe preoperative pain; respective proportions were 91% and 89% at 5-year follow-up. For revision THA, respective proportions were 84% and 77% at 2 years and 80% and 78% at 5 years. In the primary THA cohort, up to 4% with moderate and 17% with severe preoperative ADL limitation reported severe limitation in the respective activity 2 years post-primary THA; at 5 years, the respective proportions were up to 7% and 20%. Respective proportions for revision THA were up to 10% and 26% at 2 years and 13% and 30% at 5 years.
Conclusions. These comprehensive data for patient-level clinically meaningful improvements in pain and seven key ADLs can help patients set realistic goals for improvement after THA.
PMCID: PMC3651614  PMID: 23382362
pain; activity limitation; activities of daily living; function; functional limitation; total hip replacement; arthroplasty; joint replacement; outcomes; patient-reported outcomes; primary; revision
2.  Better Functional and Similar Pain Outcomes in Osteoarthritis compared to Rheumatoid arthritis after primary total knee arthroplasty: A cohort study 
Arthritis care & research  2013;65(12):10.1002/acr.22090.
To determine the association of the underlying diagnosis with limitation in activities of daily living (ADLs) and pain in patients undergoing primary total knee arthroplasty (TKA).
Prospectively collected data from the Mayo Clinic Total Joint Registry were used to assess the association of diagnosis with moderate-severe limitation in activities of daily living (ADLs) and moderate-severe pain and at 2- and 5-years after primary TKA using multivariable-adjusted logistic regression analyses. We calculated odds ratios (OR) and 95% confidence intervals (CI).
There were 7,139 primary TKAs at 2-years and 4,234 at 5-years. In multivariable-adjusted analyses, compared to rheumatoid arthritis (RA)/inflammatory arthritis, osteoarthritis (OA) was associated with significantly lower odds ratio (OR) [95% confidence interval (CI)] of moderate-severe ADL limitation with OR of 0.5 [95% CI: 0.3, 0.8] (p=0.004) at 2-years, and 0.5 [95% CI, 0.3, 0.9] (p=0.02) at 5-years. There was no significant association of diagnosis of OA with moderate-severe pain at 2-years with OR of 1.2 [0.5, 2.7] (p=0.68) or at 5-years with OR of 1.0 [0.3, 3.7] (p=1.0).
We found patients with OA who underwent primary TKA had better ADL outcomes compared to patients with RA/inflammatory arthritis at 2- and 5-years. On the other hand, the pain outcomes did not differ in OA vs. RA after primary TKA. This suggests discordant effect of underlying diagnosis on pain and function outcomes after TKA. These novel findings can be used to better inform both patients and surgeons about expected pain and function outcomes after primary TKA.
PMCID: PMC3855298  PMID: 23925956
Total knee replacement; arthroplasty; joint replacement; patient-reported outcomes; osteoarthritis; rheumatoid arthritis
3.  Medical and psychological comorbidity predicts poor pain outcomes after total knee arthroplasty 
Rheumatology (Oxford, England)  2013;52(5):916-923.
Objective. To study comorbidity correlates of moderate to severe pain after total knee arthroplasty (TKA).
Methods. We analysed prospectively collected Total Joint Registry data to examine whether medical (heart disease, peripheral vascular disease, renal disease, chronic obstructive pulmonary disease, diabetes and CTD) and psychological (anxiety and depression) comorbidity is associated with moderate to severe pain after primary or revision TKA. Multivariable-adjusted logistic regression simultaneously adjusted for all comorbidities, age, sex, BMI, underlying diagnosis, American Society of Anesthesiologist (ASA) class, distance from medical centre and implant fixation (only for primary TKA) was used to analyse primary and revision TKA separately.
Results. The primary TKA cohort consisted of 7139 and 4234 TKAs (response rates 65% and 57%) and the revision TKA cohort consisted of 1533 and 881 TKAs at 2 and 5 years (response rates 57% and 48%), respectively. In the primary TKA cohort, anxiety was associated with 1.4 higher odds (95% CI 1.0, 2.0) of moderate to severe index knee pain at 2 years; at 5 years, heart disease (OR 1.7; 95% CI 1.1, 2.6), depression (OR 1.7; 95% CI 1.1, 2.5) and anxiety (OR 1.9; 95% CI 1.2, 3.1) were significantly associated with moderate to severe pain. For revision TKA, CTD (OR 0.5; 95% CI 0.2, 0.9) and depression (OR 1.8; 95% CI 1.1, 3.1) were significantly associated with moderate to severe pain.
Conclusion. This study identified medical and psychological comorbidity risk factors for moderate to severe pain after primary and revision TKA. This information can be used to provide realistic outcome expectations for patients before undergoing primary or revision TKA.
PMCID: PMC3630396  PMID: 23325037
pain; function; functional limitation; total knee replacement; primary; arthroplasty; joint replacement; outcomes; patient-reported outcomes
4.  Aseptic Tibial Debonding as a Cause of Early Failure in a Modern Total Knee Arthroplasty Design 
We observed isolated tibial component debonding from the cement in one modern primary TKA design (NexGen LPS 3° tibial tray; Zimmer, Warsaw, IN, USA). This failure mechanism is sparsely reported in the literature.
We (1) assessed survivorship of this tibial tray with special emphasis on debonding; (2) described clinical and radiographic features associated with tibial failure; and (3) compared patient and radiographic features of the failures with a matched cohort.
A total of 1337 primary TKAs were performed with a cemented NexGen LPS 3° tibial tray over an 11-year period. Twenty-five knees (1.9%) were revised for tibial debonding. BMI and radiographic alignment in the tibial debonding group were compared with a matched control group. Implant survivorship was assessed using tibial debonding as the end point.
Survival free of revision from tibial debonding was 100% at 1 year and 97.8% at 5 years. The tibial failures shared a typical radiographic pattern with debonding at the cement-implant interface and subsidence into varus and flexion. We found no link between limb alignment or individual component alignment and failure because 22 of the 25 failures occurred in well-aligned knees.
Our standardized followup of patients undergoing TKA at routine intervals allowed us to discover a higher rate of revision resulting from tibial debonding. We have discontinued the use of this particular tibial tray for primary TKA and surveillance for patients undergoing TKA continues to be warranted.
Level of Evidence
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3528903  PMID: 22790529
5.  Determinants of Direct Medical Costs in Primary and Revision Total Knee Arthroplasty 
TKA procedures are increasing rapidly, with substantial cost implications. Determining cost drivers in TKA is essential for care improvement and informing future payment models.
We determined the components of hospitalization and 90-day costs in primary and revision TKA and the role of demographics, operative indications, comorbidities, and complications as potential determinants of costs.
We studied 6475 primary and 1654 revision TKA procedures performed between January 1, 2000, and September 31, 2008, at a single center. Direct medical costs were measured by using standardized, inflation-adjusted costs for services and procedures billed during the 90-day period. We used linear regression models to determine the cost impact associated with individual patient characteristics.
The largest proportion of costs in both primary and revision TKA, respectively, were for room and board (28% and 23%), operating room (22% and 17%), and prostheses (13% and 24%). Prosthesis costs were almost threefold higher in revision TKA than in primary TKA. Revision TKA procedures for infections and bone and/or prosthesis fractures were approximately 25% more costly than revisions for instability and loosening. Several common comorbidities were associated with higher costs. Patients with vascular and infectious complications had longer hospital stays and at least 80% higher 90-day costs as compared to patients without complications.
High prosthesis costs in revision TKA represent a factor potentially amenable to cost containment efforts. Increased costs associated with demographic factors and comorbidities may put providers at financial risk and may jeopardize healthcare access for those patients in greatest need.
Level of Evidence
Level IV, economic and decision analyses. See Instructions for Authors for a complete description of levels of evidence
PMCID: PMC3528929  PMID: 22864619
6.  Predictors of Activity Limitation and Dependence on Walking Aids following Primary Total Hip Arthroplasty 
Journal of the American Geriatrics Society  2010;58(12):10.1111/j.1532-5415.2010.03182.x.
To study function outcomes and their predictors after primary total hip arthroplasty (THA).
Prospective Cohort Study
Single Institution
All patients who underwent primary THA at our institution between 1993 and 2005 and were alive at the time of follow-up.
Whether sex, age, body mass index (BMI), comorbidity, anxiety, and depression predict moderate to severe activity limitation (limitation in ≥3 activities) and complete dependence on waling aids 2 and 5 years after primary THA was examined. Multivariable logistic regression adjusted for operative diagnosis, American Society of Anesthesiologists score, implant type, and distance from medical center.
At 2 years, 30.3% of participants reported moderate to severe activity limitation; at 5 years, 35% of participants reported moderate to severe activity limitation. Significant predictors of moderate to severe activity limitations at 2-year follow-up were female sex (odds ratio (OR)=1.2, 95% confidence interval (CI)=1.1–1.4), aged 71 to 80 (OR=2.0, 95% CI=1.6–2.5), aged 80 and older (OR=4.5, 95% CI=3.4–6.0), depression (OR=2.1, 95% CI=1.6–2.7), and BMI greater than 30. At 5-year follow-up, significant predictors were aged 71 to 80 (OR=1.7, 95% CI=1.3–2.2), older than 80 (OR=4.3, 95% CI=2.8–6.6), depression (OR=2.3, 95% CI=1.6–3.4), and BMI greater than 30.Significant predictors of complete dependence on walking aids at 2 years were female sex (OR=2.0, 95% CI=1.4–2.7), aged 71 to 80 (OR=2.4, 95% CI=1.4–4.2), older than 80 (OR=11.4, 95% CI=6.0–21.9), higher Deyo-Charlson score (OR=1.5, 95% CI=(1.1–1.2) for 5-point increase, depression (OR=2.0, 95% CI=1.2–3.4), and BMI greater than 35. Each of these factors also significantly predicted complete dependence on walking at 5-year follow-up, with similar odds ratios, except that BMI 30–34.9 was not significantly associated.
Higher BMI, depression, older age, and female sex predict activity limitation and complete dependence on walking aids 2 and 5 years after primary THA.
PMCID: PMC3850176  PMID: 21143444
Primary Total Hip Arthroplasty; THA; Predictors; Activity Limitation; Function; walking aids
7.  Diabetes: A Risk Factor for Poor Functional Outcome after Total Knee Arthroplasty 
PLoS ONE  2013;8(11):e78991.
To assess the association of diabetes with postoperative limitation of activities of daily living (ADLs) after primary total knee arthroplasty (TKA).
Methodology/Principal Findings
We used the prospectively collected data from the Mayo Clinic Total Joint Registry to assess the association of diabetes and diabetes with complications with moderate-severe ADL limitation 2- and 5-years after primary TKA. Multivariable logistic regression with general estimating equations adjusted for preoperative ADL limitation, comorbidity and demographic and clinical covariates. Odds ratio (OR) and 95% confidence interval (CI) are presented. 7,139 primary TKAs at 2-years and 4,234 at 5-years constituted the cohorts. In multivariable-adjusted analyses, diabetes was associated with higher odds of moderate-severe limitation at 2- and 5-years, 1.71 (95% CI: 1.26, 2.32; P = 0.001) and 1.66 (95% CI: 1.13, 2.46; P = 0.01). Respective ORs for patients with diabetes with complications were 2.73 (95% CI: 1.47, 5.07; P = 0.001) and 2.73 (95% CI: 1.21, 6.15; P = 0.016). Sensitivity analyses that adjusted for anxiety and depression or anxiety, depression and ipsilateral hip involvement showed minimal attenuation of magnitude of the association.
In this large study of patients who underwent primary TKA, diabetes as well as its severity were independently associated with poorer functional outcome. Given the increasing rates of both diabetes as well as arthroplasty, more insight is needed into disease-related and treatment-related factors that underlie this higher risk of ADL limitation in patients with diabetes. Poor functional outcomes may be preventable by modifying the control of diabetes and associated comorbidity in pre- and post-arthroplasty periods.
PMCID: PMC3827297  PMID: 24236080
8.  Tantalum Acetabular Cups Provide Secure Fixation in THA after Pelvic Irradiation at Minimum 5-year Followup 
Pelvic radiation has been commonly used to treat gastrointestinal, genitourinary, or hematopoietic malignancies. Conventional THA in these patients reportedly have high rates of fixation failure. Although secure short-term fixation reportedly occurs with trabecular metal implants following pelvic radiation, it is unclear whether the fixation is durable.
We determined the survival of trabecular metal acetabular components in patients having THA following pelvic radiation and assessed function and radiographic loosening.
We retrospectively reviewed 29 patients with prior pelvic radiation who had 34 arthroplasties using trabecular metal acetabular components from 1998 and 2005. The mean pelvic radiation dose was 6300 cGy. We collected the following data: patient demographics, surgery and implant information, clinical and radiographic followup, and tumor and radiotherapy related details. We obtained Harris hip scores (HHS) on all patients. Ten patients died of disease prior to 5 years and two patients were excluded, leaving 17 patients (22 hips) with a minimum of 5 years of clinical (mean, 78 months; median, 71; range, 57–116) and radiographic (mean, 73; median, 65; range, 51–116) followup.
All implants were in place in the surviving patients. The mean HHS improved from 36 preoperatively to 80 at latest followup. There were no reoperations for any reason, and we observed no implant loosening or migration at final followup in surviving or deceased patients.
Tantalum trabecular metal acetabular components restored function and provided durable reconstruction in patients undergoing THA following prior pelvic radiation. We observed no clinical or radiographic failures at a minimum 5-year followup.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3462848  PMID: 22576931
9.  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
10.  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
11.  Surgical Technique: Porous Tantalum Reconstruction for Destructive Nonprimary Periacetabular Tumors 
Large bone loss and frequently irradiated existing bone make reconstructing metastatic and other nonprimary periacetabular tumors challenging. Although existing methods are initially successful, they may fail with time. Given the low failure rates of porous tantalum acetabular implants in other conditions with large bone loss or irradiated bone, we developed a technique to use these implants in these neoplastic cases where others might fail.
Description of Technique
After local tumor curettage, a large uncemented tantalum shell (sometimes with tantalum augments) was fixed to remaining bone using numerous screws. When substantial medial bone loss was present, an antiprotrusio cage was placed over the top of the cup and secured to remaining ilium and ischium.
Patients and Methods
We retrospectively reviewed 20 patients who underwent THAs for neoplastic bone destruction with the described technique. Their mean age was 60 years (range, 22–80 years). We recorded pain and ambulatory status, pain medication use, and Harris hip scores. We assessed for progressive radiolucent lines and component migration on followup radiographs. Eleven of the 20 patients died at a mean of 17 months after surgery. The minimum followup for surviving patients was 26 months (mean, 56 months; range, 26–85 months).
Harris hip scores improved from a mean 32 preoperatively to a mean 74 postoperatively. We observed no cases of progressive radiolucent lines or component migration. Complications included one perioperative death, two superficial infections, one deep vein thrombosis, and one dislocation.
Our initial experience has made tantalum reconstruction our preferred method for dealing with major periacetabular neoplastic bone loss. Additional studies comparing this technique with alternatives are required.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3254739  PMID: 21989784
12.  Reinfection after two-stage revision for periprosthetic infection of total knee arthroplasty 
International Orthopaedics  2011;36(1):65-71.
Limited data exist regarding the long-term results or risk factors for failure after two-stage reimplantation for periprosthetic knee infection. The purpose of this retrospective review was to investigate infection-free implant survival and identify variables associated with reinfection after this procedure. Furthermore, a staging system was evaluated as a possible prognostic tool for patients undergoing two-stage reimplantation of infected total knee arthroplasty (TKA).
In this level II, retrospective prognostic study, 368 patients with infected TKA treated with a two-stage revision protocol at our institution between 1998 and 2006 were reviewed. Patients who developed recurrent infection and an equal number of patients randomly selected for the control group were analysed for risk factors associated with treatment failure.
At the most recent follow-up, 58 (15.8%) patients had developed reinfection after the two-stage reimplantation. The median time to reinfection was 1,303 days (3.6 years), with follow-up time ranging from six to 2,853 days (7.8 years). The strongest positive predictors of treatment failure included chronic lymphoedema [hazard ratio (HR) = 2.28, 95% confidence interval (CI) 1.16–4.48; p = 0.02),and revision between resection and definitive reimplantation (HR = 2.13, 95% CI 1.20–3.79; p = 0.01, whereas patients treated with intravenously administered Cefazolin had a significant reduction in recurrent infection rate (HR = 0.48, 95% CI 0.25–0.90; p = 0.02).
Our findings should be of help in counselling patients regarding their prognosis when faced with two-stage exchange for infected TKA and provide a basis for future comparisons.
PMCID: PMC3251662  PMID: 21553042
13.  Cardiac and Thromboembolic Complications and Mortality in Patients Undergoing Total Hip and Total Knee Arthroplasty 
Annals of the Rheumatic Diseases  2011;70(12):2082-2088.
Study 90-day cardiac and thromboembolic complications and all-cause mortality following total hip or knee arthroplasty (THA/TKA).
In a population-based cohort of all Olmsted County residents who underwent a THA or TKA between 1994 and 2008, we assessed 90-day occurrence and predictors of cardiac complications (myocardial infarction, cardiac arrhythmia or congestive heart failure), thromboembolic complications (deep venous thrombosis (DVT) or pulmonary embolism (PE)) and mortality.
Among the Olmsted County THA and TKA cohorts, 90-day complication rates were as follows: cardiac, 15.8% and 6.9%; thromboembolic, 4.9% and 4.0%; and mortality, 0.7% and 0.4%, respectively. Unadjusted frequency of cardiac/thromboembolic events differed by history of prior respective event. In multivariable-adjusted logistic regression analyses, ASA class III–IV (OR, 6.1, 95% CI:1.6, 22.8) and higher Deyo-Charlson comorbidity score (OR, 1.2, 95% CI:1.0,1.4) were significantly associated with odds of 90-day cardiac event post-THA in patients with no known prior cardiac event. In those with known prior cardiac disease, ASA class III–IV (OR, 4.4, 95% CI:2.0, 9.9), male gender (OR, 0.5, 95% CI:0.3,0.9) and history of thromboembolic disease (OR, 3.2; 95% CI:1.4,7.0) were significantly associated with odds of cardiac complication 90-day post-THA. No significant predictors of thromboembolism were found in THA patients.
In TKA patients with no prior cardiac history, age >65 years (OR, 4.1, 95% CI:1.2, 14.0), and ASA class III–IV (OR, 2.8, 95% CI:1.1,6.8) and in TKA patients with known cardiac disease, ASA class III–IV (OR, 3.2, 95% CI:1.8,5.7) was significantly associated with odds of 90-day cardiac event. In TKA patients with no prior thromboembolic disease, male gender (OR, 0.5, 95% CI:0.2,0.9) and higher Charlson index (OR, 1.2, 95% CI:1.1,1.3) and in patients with known thromboembolic disease, higher Charlson index score (OR, 1.1, 95% CI:1.1,1.4) was associated with odds of 90-day thromboembolic event.
Older age, higher comorbidity, higher ASA class and prior history of cardiac/thromboembolic disease was associated with an increased risk of 90-day cardiac and thromboembolic complications.
PMCID: PMC3315837  PMID: 22021865
Cardiac; Thromboembolic; Total Hip Arthroplasty; Total Knee Arthroplasty; Mortality
14.  Peptic ulcer disease and Pulmonary disease are Associated with Risk of Periprosthetic Fracture after Primary Total Knee Arthroplasty 
Arthritis care & research  2011;63(10):1471-1476.
To assess the association of specific comorbidities with periprosthetic fractures after primary total knee replacement (TKA)
We used the prospectively collected data in the Mayo Clinic Total Joint Registry from 1989-2008 on all patients who had undergone primary TKA. The outcome of interest was postoperative periprosthetic fractures during the follow-up. Main predictors of interest were comorbidities grouped from the validated Deyo-Charlson index. Multivariable-adjusted Cox regression analyses adjusted for gender, age, body mass index (BMI), American Society of Anesthesiology (ASA) class, operative diagnosis and implant fixation. Hazard ratios and 95% confidence intervals were calculated.
We included 17,633 primary TKAs with a mean follow-up of 6.3 years. The mean age was 68 years, 55% were women and mean BMI was 31. There were 188 postoperative periprosthetic fractures on postoperative day one or later; 162 fractures (86%) occurred postoperative day 90 day or later. In multivariable analyses that simultaneously adjusted for all comorbidities and other variables (age, gender, BMI, ASA, operative diagnosis, cement status), two conditions were significantly associated with increased hazard of postoperative periprosthetic fractures: peptic ulcer disease, hazard ratio of 1.87 (95% confidence interval:1.28, 2.75; p=0.0014); and chronic obstructive pulmonary disease (COPD) hazard ratio of 1.62 (95% confidence interval:1.10, 2.40; p=0.02).
Peptic ulcer disease and COPD are associated with higher risk of periprosthetic fractures after primary TKA. This may be related to the disease or their treatments, which needs further study. Identification of specific risk factor may allow for implementation of intervention strategies to reduce this risk.
PMCID: PMC3183369  PMID: 21748860
Total knee arthroplasty; total knee replacement; periprosthetic fracture; predictors; risk factors; comorbidity; Primary TKA
15.  Higher Body Mass Index Is Not Associated with Worse Pain Outcomes After Primary or Revision Total Knee Arthroplasty (TKA) 
The Journal of arthroplasty  2010;26(3):366-374.e1.
We assessed whether higher Body Mass Index (BMI) is associated with higher risk of moderate-severe knee pain 2- and 5-years after primary or revision Total Knee Arthroplasty (TKA). We adjusted for gender, age, comorbidity, operative diagnosis and implant fixation in multivariable logistic regression. BMI (reference, <25 kg/m2) was not associated with moderate-severe knee pain at 2-years post-primary TKA (odds ratio (95% confidence interval): 25-29.9, 1.02 (0.75,1.39), p=0.90; 30-34.9, 0.93 (0.65,1.34), p=0.71; 35-39.9, 1.16 (0.77,1.74), p=0.47; ≥40, 1.09 (0.69,1.73), (all p-values ≥0.47). Similarly, BMI was not associated with moderate-severe pain at 5-year primary TKA and at 2- and 5-yr revision TKA follow-up. Lack of association of higher BMI with poor pain outcomes post-TKA implies that TKA should not be denied to obese patients for fear of suboptimal outcomes.
PMCID: PMC2930933  PMID: 20413245
16.  Failed Metal-on-Metal Hip Arthroplasties: A Spectrum of Clinical Presentations and Operative Findings 
A number of recent reports have described novel failure mechanisms of metal-on-metal bearings in total and resurfacing hip arthroplasty. Hip arthroplasties with metal-on-metal articulations are also subject to the traditional methods of failure seen with different bearing couples. There is currently little information in the literature to help guide timely clinical evaluation and management of these patients.
We therefore describe the (1) clinical presentations; (2) reasons for failure; (3) operative findings; and (4) histologic findings in patients with failed metal-on-metal hip arthroplasties.
We retrospectively identified all 37 patients (37 hips) with metal on metal total hip or resurfacing arthroplasties who underwent revision over the past 3 years at our institution. Relevant clinical, radiographic, laboratory, intraoperative, and histopathologic findings were analyzed for all patients.
Of the 37 patients, 10 were revised for presumed hypersensitivity specific to the metal-on-metal articulation. This group included eight patients with tissue histology confirming chronic inflammation with lymphocytic infiltration, eight with aseptic loosening of a monoblock screwless uncemented acetabular component, two with iliopsoas impingement associated with a large-diameter femoral head, and three with femoral neck fracture after resurfacing arthroplasty; the remainder of the patients were revised for infection, instability, component malposition, and periprosthetic fracture.
Increased awareness of the modes of failure will bring to light the potential complications particular to metal-on-metal articulations while placing these complications into the context of failures associated with all hip arthroplasties. This novel clinical information should be valuable for the practicing surgeon faced with this patient population.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2919884  PMID: 20559767
17.  Limitations of Structural Allograft in Revision Total Knee Arthroplasty 
Management of large bone defects in total knee arthroplasty (TKA) usually has involved modular prostheses with metal augments, structural allografts, and megaprostheses. We retrospectively reviewed the outcome of treatment of major bone defects for 74 patients (79 knees) who had revision TKAs with structural allografts; nine patients were lost to followup before 5 years, leaving 65 patients (70 knees, or 88%) followed for a minimum of 5 years or until revision or death. Medical records, radiographs, patient surveys, and correspondence were used for all data. Sixteen patients (22.8%) had failed reconstructions and underwent additional revision surgery; eight of the 16 were secondary to allograft failure, three were secondary to failure of a component not supported by allograft, and five were secondary to infection. In patients not requiring revision surgery, the Knee Society score improved from 49 preoperatively to 87 postoperatively. We observed revision-free survival of 80.7% (95% confidence interval, 71.7–90.8) at 5 years and 75.9% (95% confidence interval, 65.6–87.8) at 10 years. Our data support the selective use of structural allograft for large cavitary defects encountered during TKA. However, the rates of complications and reoperations suggest efforts to improve results or develop more durable alternative methods are warranted for these challenging reconstructions.
Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2635432  PMID: 19130161
18.  C-Reactive Protein, Erythrocyte Sedimentation Rate and Orthopedic Implant Infection 
PLoS ONE  2010;5(2):e9358.
C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been shown to be useful for diagnosis of prosthetic hip and knee infection. Little information is available on CRP and ESR in patients undergoing revision or resection of shoulder arthroplasties or spine implants.
We analyzed preoperative CRP and ESR in 636 subjects who underwent knee (n = 297), hip (n = 221) or shoulder (n = 64) arthroplasty, or spine implant (n = 54) removal. A standardized definition of orthopedic implant-associated infection was applied. Receiver operating curve analysis was used to determine ideal cutoff values for differentiating infected from non-infected cases. ESR was significantly different in subjects with aseptic failure infection of knee (median 11 and 53.5 mm/h, respectively, p = <0.0001) and hip (median 11 and 30 mm/h, respectively, p = <0.0001) arthroplasties and spine implants (median 10 and 48.5 mm/h, respectively, p = 0.0033), but not shoulder arthroplasties (median 10 and 9 mm/h, respectively, p = 0.9883). Optimized ESR cutoffs for knee, hip and shoulder arthroplasties and spine implants were 19, 13, 26, and 45 mm/h, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 89 and 74% for knee, 82 and 60% for hip, and 32 and 93% for shoulder arthroplasties, and 57 and 90% for spine implants. CRP was significantly different in subjects with aseptic failure and infection of knee (median 4 and 51 mg/l, respectively, p<0.0001), hip (median 3 and 18 mg/l, respectively, p<0.0001), and shoulder (median 3 and 10 mg/l, respectively, p = 0.01) arthroplasties, and spine implants (median 3 and 20 mg/l, respectively, p = 0.0011). Optimized CRP cutoffs for knee, hip, and shoulder arthroplasties, and spine implants were 14.5, 10.3, 7, and 4.6 mg/l, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 79 and 88% for knee, 74 and 79% for hip, and 63 and 73% for shoulder arthroplasties, and 79 and 68% for spine implants.
CRP and ESR have poor sensitivity for the diagnosis of shoulder implant infection. A CRP of 4.6 mg/l had a sensitivity of 79 and a specificity of 68% to detect infection of spine implants.
PMCID: PMC2825262  PMID: 20179760
19.  Comparison of wear and osteolysis in hip replacement using two different coatings of the femoral stem 
International Orthopaedics  2004;28(4):206-210.
We compared the clinical and radiographic results of two matched series of total hip arthroplasties, one with hydroxyapatite-coated femoral stems, the other with a similar but porous-coated femoral stem. The prevalence of radiographic osteolysis was 16% in hips with hydroxyapatite-coated stems and 43% in hips with porous-coated femoral stems. In hips with hydroxyapatite-coated stems, osteolysis was always limited to Gruen zones 1 and 7. In contrast, distal osteolysis was present around 26% of the porous-coated stems. At 7 years, the survival-free rate of distal osteolysis was 100% in hips with hydroxyapatite-coated stems but 90% in hips with porous-coated stems (p=0.04). Circumferential hydroxyapatite coating of the femoral component reduced the occurrence of osteolysis and eliminated distal osteolysis at 5–10 years of follow-up. In addition, hydroxyapatite coating did not alter the wear rate.
PMCID: PMC3456935  PMID: 15118841

Results 1-19 (19)