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1.  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.
doi:10.1093/rheumatology/kes402
PMCID: PMC3630396  PMID: 23325037
pain; function; functional limitation; total knee replacement; primary; arthroplasty; joint replacement; outcomes; patient-reported outcomes
2.  Predictors of Moderate-Severe Functional Limitation after Primary Total Knee Arthroplasty (TKA): 4,701 TKAs at 2-years and 2,935 TKAs at 5-years 
Objective
Investigate whether body mass index (BMI), comorbidity, gender and age predict patient-reported functional limitation 2- and 5-years after Primary Total Knee Arthroplasty (TKA).
Methods
Overall moderate-severe activity limitation was defined as ≥2 activities (walking, stairs, rising chair) with moderate-severe limitation. Complete dependence on walking-aids or inability to walk was assessed (reference, no dependence). Multivariable logistic regressions were adjusted additionally for income, diagnosis, distance from medical center, ASA score and implant type.
Results
Overall moderate-severe activity limitation was reported by 20.7% at 2-years and 27.1% at 5-years. Significantly predictors of overall moderate-severe activity limitation 2-years post-TKA (odds (95% confidence interval)) were: BMI 30–34.9, 1.5 (1.0,2.0), 35–39.9, 1.8 (1.3,2.7) and ≥40, 3.0 (2.0,4.5) versus BMI≤25; higher Deyo-Charlson index, 1.7 (1.4,2.2) per 5-point increase; female gender, 2.0 (1.7,2.5); age 71–80, 2.1 (1.5,2.8) and age>80, 4.1 (2.7,6.1) versus age≤60.
At 5-years post-TKA, significant predictors of overall moderate-severe activity limitation were: BMI 35–39.9, 2.1 (1.4,3.3) and ≥40, 3.9 (2.3,6.5); higher Deyo-Charlson index, 1.4 (1.0,1.8); female gender, 2.2 (1.7,2.7); age 71–80, 2.4 (1.7,3.5) and age>80, 4.7 (2.8,7.9). Complete dependence on walking-aids was significantly higher at 2- and 5-years, respectively, in patients with: higher comorbidity, 2.3 (1.5,3.3) and 2.1 (1.4,3.2); female gender 2.4 (1.5,3.9) and1.7 (1.1,2.6); ;age 71–80, 1.6(1.03,2.5) and 2.1(1.2,3.4); and age >80, 3.2 (1.6,6.7) and 5.1 (2.3,11.0).
Conclusions
Modifiable (BMI, comorbidity) and non-modifiable predictors (age, gender) increased the risk of functional limitation and walking-aid dependence after primary TKA. Interventions targeting comorbidity and BMI pre-operatively may positively impact function post-TKA.
doi:10.1016/j.joca.2009.12.001
PMCID: PMC3882060  PMID: 20060950
Predictors; Functional Limitation; Total Knee Arthroplasty; Body Mass Index; Comorbidity; Gender; Age
3.  Are outcomes after total knee arthroplasty worsening over time? A time-trends study of activity limitation and pain outcomes 
Background
To examine whether function and pain outcomes of patients undergoing primary total knee arthroplasty (TKA) are changing over time.
Methods
The Mayo Clinic Total Joint Registry provided data for time-trends in preoperative and 2-year post-operative activity limitation and pain in primary TKA patients from 1993-2005. We used chi-square test and analysis for variance, as appropriate. Multivariable-adjusted analyses were done using logistic regression.
Results
In a cohort of 7,229 patients who underwent primary TKA during 1993-2005, mean age was 68.4 years (standard deviation (SD), 9.8), mean BMI was 31.1 (SD, 6.0) and 55% were women. Crude estimates showed that preoperative moderate-severe overall limitation were seen in 7.3% fewer patients and preoperative moderate-severe pain in 2.7% more patients in 2002-05, compared to 1992-95 (p < 0.001 for both). At 2-years, crude estimates indicated that compared to 1992-95, moderate-severe post-TKA overall limitation was seen in 4.7% more patients and moderate-severe post-TKA pain in 3.6% more patients in 2002-05, both statistically significant (p ≤ 0.018) and clinically meaningful. In multivariable-adjusted analyses that adjusted for age, sex, anxiety, depression, Deyo-Charlson index, body mass index and preoperative pain/limitation, patients had worse outcomes 2-year post-TKA in 2002-2005 compared to 1993-95 with an odds ratio (95% confidence interval (CI); p-value) of 1.34 (95% CI: 1.02, 1.76, p = 0.037) for moderate-severe activity limitation and 1.79 (95% CI: 1.17, 2.75, p = 0.007) for moderate-severe pain.
Conclusion
Patient-reported function and pain outcomes after primary TKA have worsened over the study period 1993-95 to 2002-05. This time-trend is independent of changes in preoperative pain/limitation and certain patient characteristics.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2474-15-440) contains supplementary material, which is available to authorized users.
doi:10.1186/1471-2474-15-440
PMCID: PMC4301928  PMID: 25519240
Total knee replacement; Time trends; Arthroplasty; Joint replacement; Pain; Function
4.  The Impact of Gender, Age, and Preoperative Pain Severity on Pain After TKA 
Do gender and age affect knee arthroplasty outcomes? In a cohort of patients who underwent primary or revision TKA between 1996 and 2004 and responded to a followup questionnaire 2 and 5 years after arthroplasty, we investigated the impact of gender and age on the prevalence of moderate or severe post-TKA knee pain (primary TKA: 2 years, 5290; 5 years, 2602; revision TKA: 2 years, 1109; 5 years, 505). Moderate-severe pain was higher in women than men after primary TKA at 2 and 5 years (9% versus 6.6% and 7.9% versus 6.5%) and post-revision TKA at 2 and 5 years (28.6% versus 22% and 28.9% versus 18.3%). More women compared to men and fewer patients between 61 and 70 years (versus patients ≤ 60) had moderate-severe pain 2 years after primary TKA adjusting for gender, age, and preoperative pain severity. In the post-revision TKA group, the odds of moderate-severe pain were lower in patients older than 80 years (versus those ≤ 60) at 2 years and higher in patients with moderate-severe preoperative pain at 2 and 5 years postoperatively, after adjustment for gender, age, and preoperative pain severity. We conclude female gender, younger age, and worse preoperative pain predict greater risk of moderate-severe pain postoperatively in patients with primary and revision TKA.
Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-008-0399-9
PMCID: PMC2565033  PMID: 18679762
5.  Ipsilateral lower extremity joint involvement increases the risk of poor pain and function outcomes after hip or knee arthroplasty 
BMC Medicine  2013;11:144.
Background
Poor pain and function outcomes are undesirable after an elective surgery such as total hip or knee arthroplasty (THA/TKA). Recent studies have indicated that the presence of contralateral joint influences outcomes of THA/TKA, however the impact of ipsilateral knee/hip involvement on THA/TKA outcomes has not been explored. The objective of this study was to assess the association of ipsilateral knee/hip joint involvement on short-term and medium-term pain and function outcomes after THA/TKA.
Methods
In this retrospective study of prospectively collected data, we used the data from the Mayo Clinic Total Joint Registry to assess the association of ipsilateral knee or hip joint involvement with moderate to severe pain and moderate to severe activity limitation at 2-year and 5-year follow-up after primary and revision THA and TKA using multivariable-adjusted logistic regression analyses.
Results
At 2 years, 3,823 primary THA, 4,701 primary TKA, 1,218 revision THA and 725 revision TKA procedures were studied. After adjusting for multiple covariates, ipsilateral knee pain was significantly associated with outcomes after primary THA (all P values <0.01): (1) moderate to severe pain: at 2 years, odds ratio (OR), 2.3 (95% confidence interval (CI) 1.5 to 3.6); at 5 years, OR 1.8 (95% CI 1.1 to 2.7); (2) moderate to severe activity limitation: at 2 years, OR 3.1 (95% CI 2.3 to 4.3); at 5 years, OR 3.6 (95% CI 2.6 to 5.0). Ipsilateral hip pain was significantly associated with outcomes after primary TKA (all P values <0.01): (1) moderate to severe pain: at 2 years, OR 3.3 (95% CI 2.3 to 4.7); at 5 years, OR 1.8 (95% CI 1.1 to 2.7); (2) moderate to severe activity limitation: at 2 years, OR 3.6 (95% CI 2.6 to 4.9); at 5 years, OR 2.2 (95% CI 1.6 to 3.2). Similar associations were noted for revision THA and TKA patients.
Conclusions
To the best of our knowledge, this is the first study showing that the presence of ipsilateral joint involvement after THA or TKA is strongly associated with poor pain and function outcomes. A potential way to improve outcomes is to address ipsilateral lower extremity joint involvement.
doi:10.1186/1741-7015-11-144
PMCID: PMC3681648  PMID: 23738845
Arthroplasty; Ipsilateral; Joint replacement; Outcomes; Risk factors; Total hip replacement; Total knee replacement
6.  Clinical predictors of elective total joint replacement in persons with end-stage knee osteoarthritis 
Background
Arthritis is a leading cause of disability in the United States. Total knee arthroplasty (TKA) has become the gold standard to manage the pain and disability associated with knee osteoarthritis (OA). Although more than 400 000 primary TKA surgeries are performed each year in the United States, not all individuals with knee OA elect to undergo the procedure. No clear consensus exists on criteria to determine who should undergo TKA. The purpose of this study was to determine which clinical factors will predict the decision to undergo TKA in individuals with end-stage knee OA. Knowledge of these factors will aid in clinical decision making for the timing of TKA.
Methods
Functional data from one hundred twenty persons with end-stage knee OA were obtained through a database. All of the individuals complained of knee pain during daily activities and had radiographic evidence of OA. Functional and clinical tests, collectively referred to as the Delaware Osteoarthritis Profile, were completed by a physical therapist. This profile consisted of measuring height, weight, quadriceps strength and active knee range of motion, while functional mobility was assessed using the Timed Up and Go (TUG) test and the Stair Climbing Task (SCT). Self-perceived functional ability was measured using the activities of daily living subscale of the Knee Outcome Survey (KOS-ADLS). A logistic regression model was used to identify variables predictive of TKA use.
Results
Forty subjects (33%) underwent TKA within two years of evaluation. These subjects were significantly older and had significantly slower TUG and SCT times (p < 0.05). Persons that underwent TKA were also significantly weaker, had lower self-reported function and had less knee extension than persons who did not undergo TKA. No differences between groups were seen for BMI, gender, knee flexion ROM and unilateral versus bilateral joint disease. Using backward regression, age, knee extension ROM and KOS-ADLS together significantly predicted whether or not a person would undergo TKA (p ≤ 0.001, R2 = 0.403).
Conclusions
Younger patients with full knee ROM who have a higher self-perception of function are less likely to undergo TKA. Physicians and clinicians should be aware that potentially modifiable factors, such as knee ROM can be addressed to potentially postpone the need for TKA.
doi:10.1186/1471-2474-11-86
PMCID: PMC2877653  PMID: 20459622
7.  Predictors of use of pain medications for persistent knee pain after primary Total Knee Arthroplasty: a cohort study using an institutional joint registry 
Arthritis Research & Therapy  2012;14(6):R248.
Introduction
To study the use of pain medications for persistent index knee pain and their predictors after primary Total Knee Arthroplasty (TKA).
Methods
The Mayo Total Joint Registry collects patient-reported data including pain medication use on all patients who undergo TKA. We used data from patients who underwent primary TKA from 1993-2005. We examined whether gender, age (reference, ≤60 yrs), body mass index (BMI; reference, <25 kg/m2), comorbidities measured by Deyo-Charlson index (5-point increase), anxiety and depression predicted use of pain medications (non-steroidal anti-inflammatory drugs (NSAIDs) and opioids) 2- and 5-years after primary TKA. Multivariable logistic regression additionally adjusted for operative diagnosis, American Society of Anesthesiologists (ASA) score, implant fixation and distance from the medical center.
Results
7,139 of the 10,957 eligible (65%) at 2-years and 4,234 of 7,404 eligible (57%) completed questionnaires. Significant predictors of NSAIDs use were (Odds ratio (95% confidence interval)): male gender at 2- and 5-years, 0.5 (0.4, 0.6) and 0.6 (0.5, 0.8); age >70-80 years, 0.7 (0.5, 0.9), 0.6 (0.4, 0.8); and depression, 1.4 (1.0, 1.8) and 1.7 (1.1, 2.5). BMI ≥40 was associated with NSAIDs use only at 2-years, 1.6 (1.1, 2.5). Significant predictors of opioid pain medication use at 2- and 5-years were: male gender, 0.5 (0.3, 0.9) and 0.4 (0.2, 0.8); age >70-80 years, 0.3 (0.1, 0.6), 0.3 (0.1, 0.8); and anxiety, 3.0 (1.6, 5.7) and 4.0 (1.7, 9.4).
Conclusions
Female gender and younger age were associated with higher risk of use of NSAIDs and opioids after primary TKA. Depression was associated with higher NSAID use and anxiety with higher opioid pain medication use after primary TKA.
doi:10.1186/ar4091
PMCID: PMC3674590  PMID: 23157942
8.  Depression in primary TKA and higher medical comorbidities in revision TKA are associated with suboptimal subjective improvement in knee function 
Background
To characterize whether medical comorbidities, depression and anxiety predict patient-reported functional improvement after total knee arthroplasty (TKA).
Methods
We analyzed the prospectively collected data from the Mayo Clinic Total Joint Registry for patients who underwent primary or revision TKA between 1993–2005. Using multivariable-adjusted logistic regression analyses, we examined whether medical comorbidities, depression and anxiety were associated with patient-reported subjective improvement in knee function 2- or 5-years after primary or revision TKA. Odds ratios (OR), along with 95% confidence intervals (CI) and p-value are presented.
Results
We studied 7,139 primary TKAs at 2- and 4,234 at 5-years; and, 1,533 revision TKAs at 2-years and 881 at 5-years. In multivariable-adjusted analyses, we found that depression was associated with significantly lower odds of 0.5 (95% confidence interval [CI]: 0.3 to 0.9; p = 0.02) of ‘much better’ knee functional status (relative to same or worse status) 2 years after primary TKA. Higher Deyo-Charlson index was significantly associated with lower odds of 0.5 (95% CI: 0.2 to 1.0; p = 0.05) of ‘much better’ knee functional status after revision TKA for every 5-point increase in score.
Conclusions
Depression in primary TKA and higher medical comorbidity in revision TKA cohorts were associated with suboptimal improvement in index knee function. It remains to be seen whether strategies focused at optimization of medical comorbidities and depression pre- and peri-operatively may help to improve TKA outcomes. Study limitations include non-response bias and the use of diagnostic codes, which may be associated with under-diagnosis of conditions.
doi:10.1186/1471-2474-15-127
PMCID: PMC3990241  PMID: 24725511
Total knee arthroplasty; Knee function; Functional limitation; Primary; Arthroplasty; Joint replacement; Outcomes; Patient-reported outcomes
9.  Income and patient-reported outcomes (PROs) after primary total knee arthroplasty 
BMC Medicine  2013;11:62.
Background
To assess whether income is associated with patient-reported outcomes (PROs) after primary total knee arthroplasty (TKA).
Methods
We used prospectively collected data from the Mayo Clinic Total Joint Registry to assess the association of income with index knee functional improvement, moderate to severe pain and moderate to severe activity limitation at 2-year and 5-year follow-up after primary TKA using multivariable-adjusted logistic regression analyses.
Results
There were 7, 139 primary TKAs at 2 years and 4, 234 at 5 years. In multivariable-adjusted analyses, at 2-year follow-up, compared to income > US$45, 000, lower incomes of ≤ US$35, 000 and > US$35, 000 to 45, 000 were associated (1) significantly with moderate to severe pain with an odds ratio (OR) 0.61 (95% CI 0.40 to 0.94) (P = 0.02) and 0.68 (95% CI 0.49 to 0.94) (P = 0.02); and (2) trended towards significance for moderate to severe activity limitation with OR 0.78 (95% CI 0.60 to 1.02) (P = 0.07) and no significant association with OR 0.96 (95% CI 0.78 to 1.20) (P = 0.75), respectively. At 5 years, odds were not statistically significantly different by income, although numerically they favored lower income. In multivariable-adjusted analyses, overall improvement in knee function was rated as 'better' slightly more often at 2 years by patients with income in the ≤ US$35, 000 range compared to patients with income > US$45, 000, with an OR 1.9 (95% CI 1.0 to 3.6) (P = 0.06).
Conclusions
We found that patients with lower income had better pain outcomes compared to patients with higher income. There was more improvement in knee function, and a trend towards less overall activity limitation after primary TKA in lower income patients compared to those with higher incomes. Insights into mediators of these relationships need to be investigated to understand how income influences outcomes after TKA.
doi:10.1186/1741-7015-11-62
PMCID: PMC3641978  PMID: 23497272
arthroplasty; income; joint replacement; patient-reported outcomes; risk factor; total knee replacement
10.  The clinical outcome of revision knee replacement after unicompartmental knee arthroplasty versus primary total knee arthroplasty: 8–17 years follow-up study of 49 patients 
International Orthopaedics  2009;34(5):649-653.
When unicompartmental knee arthroplasty (UKA) failure occurs, a revision procedure to total knee arthroplasty (TKA) is often necessary. We compared the long-term results of this procedure to primary TKA and evaluated whether they are clinically comparable. Twenty-one patients underwent UKA conversion to TKA between 1991 and 2000. The results of these patients were compared to the group of 28 primary TKA patients with the same age, sex and operation time point. The long-term outcomes were evaluated using clinical and radiological analysis. The mean follow-up period of the patients was 10.5 years. The UKA revision patients were more dissatisfied, as measured by the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scale (0–100 mm) compared to the primary TKA patients (pain 18.1/7.8; p = 0.014; stiffness 25.7/14.4, p = 0.024; physical function 19.0/14.8, p = 0.62). Two patients were revised twice in the UKA revision group. There was one revision in the primary TKA group (p = 0.39). Improvement in range of motion (ROM) was better in the TKA patients compared to the UKA revision patients (8.2°/–2.6°, p = 0.0001). We suggest that UKA conversion to TKA is associated with poorer clinical outcome as compared to primary TKA.
doi:10.1007/s00264-009-0811-4
PMCID: PMC2903165  PMID: 19471929
11.  Factors affecting the quality of life after total knee arthroplasties: a prospective study 
Background
The purpose of the study is to evaluate the self-reported outcomes in the first year after primary total knee arthroplasty (TKA), and to determine factors influencing the quality of life (QoL) 6 weeks, 3, 6, and 12 months after TKA.
Methods
A cohort of patients with knee osteoarthritis undergoing primary TKA at two hospitals (a regional university hospital and a capital’s metropolitan hospital) was prospectively followed for 12 months. Patients were assessed preoperatively and at 4 postoperative time-points, with the use of self-reported measurements for pain, physical function and depression with the following evaluation tools: Western Ontario and McMaster Osteoarthritis Index [WOMAC], Knee Society Scoring system [KSS], Centre for Epidemiological Studies Depression Scale, [CES-D10] and visual analog scale [VAS] for pain). General linear modelling for repeated measures was used to evaluate the effect of each independent variable including clinical and sociodemographic data. Differences between groups at different time points were tested by the independent samples t-test.
Results
Of the 224 eligible patients, 204 (162 females, mean age 69.2) were included in the analysis. Response rate at one year was 90%. At 6 weeks after surgery, despite improvement in pain and alleviation of the depressive mood, the physical function remained less satisfactory. Females presented lower scores in terms of quality of life, both preoperatively and 6 weeks after TKA. Significant improvement was already experienced at 3 months postoperatively. According to WOMAC, KSS, CES-D10 and pain VAS scores the Qol was significantly improved 12 months after TKA (P < 0.001). CES-D10 score was positively correlated with WOMAC and pain VAS scores at all the time points assessed (P < 0.001). Age, body mass index (BMI), place of residence, level of education and social support were not significant predictors of QoL after TKA.
Conclusions
Patients experienced great improvement in their QoL after TKA in spite of a less satisfactory physical function in the first 6 weeks after surgery, with noticeable differences in the QoL among genders in the same time period. After that period all patients experienced significant improvement for all the measured parameters, until the third postoperative month with smaller changes thereafter.
doi:10.1186/1471-2474-13-116
PMCID: PMC3476961  PMID: 22748117
Total knee arthroplasty; Quality of life; Osteoarthritis; Rehabilitation
12.  Revision Surgery for Patellofemoral Problems: Should We Always Resurface? 
Background
Routine patellar resurfacing performed at the time of knee arthroplasty is controversial, with some evidence of utility in both TKA (tricompartmental) and bicompartmental knee arthroplasty. However, whether one approach results in better implant survival remains unclear.
Questions/purposes
We asked whether (1) routine patellar resurfacing in TKAs resulted in lower cumulative revision rates compared to bicompartmental knee arthroplasties, (2) patella-friendly implants resulted in lower cumulative revision rates than earlier designs, and (3) bicompartmental knee arthroplasties revised to TKAs had higher cumulative revision rates than primary TKAs.
Patients and Methods
From a community-based joint registry, we identified 8135 patients treated with 9530 cemented, all-polyethylene patella TKAs and 627 bicompartmental knee arthroplasties without patellar resurfacing. We compared age, gender, year of index procedure, diagnosis, cruciate status, revision, and revision reason.
Results
TKAs had a lower cumulative revision rate for patella-only revision than bicompartmental knee arthroplasties (0.8% versus 4.8%). Adjusting for age, bicompartmental knee arthroplasties were 6.9 times more likely to undergo patellar revision than TKAs. There was no difference in the cumulative revision rate for patella-only revisions between patella-friendly and earlier designs. The cumulative revision rate for any second revision after a patella-only revision was 12.7% for bicompartmental knee arthroplasties while that for primary TKAs was 6.3%.
Conclusions
Bicompartmental knee arthroplasties had higher revision rates than TKAs. Femoral component design did not influence the cumulative revision rate. Secondary patella resurfacing in a bicompartmental knee arthroplasty carried an increased revision risk compared to resurfacing at the time of index TKA. To reduce the probability of reoperation for patellofemoral problems, our data suggest the patella should be resurfaced at the time of index surgery.
Level of Evidence
Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-011-2036-2
PMCID: PMC3237992  PMID: 21858641
13.  Causes, Risk Factors, and Trends in Failures After TKA in Korea Over the Past 5 Years: A Multicenter Study 
Background
Failure after total knee arthroplasty (TKA) may be related to emerging technologies, surgical techniques, and changing patient demographics. Over the past decade, TKA use in Korea has increased substantially, and demographic trends have diverged from those of Western countries, but failure mechanisms in Korea have not been well studied.
Questions/purposes
We determined the causes of failure after TKA, the risk factors for failure, and the trends in revision TKAs in Korea over the last 5 years.
Methods
We retrospectively reviewed 634 revision TKAs and 20,234 primary TKAs performed at 19 institutes affiliated with the Kleos Korea Research Group from 2008 to 2012. We recorded the causes of failure after TKA using 11 complications from the standardized complication list of The Knee Society, patient demographics, information on index and revision of TKAs, and indications for index TKA. The influences of patient demographics and indications for index TKA on the risk of TKA failure were evaluated using multivariate regression analysis. The trends in revision procedures and demographic features of the patients undergoing revision TKA over the last 5 years were assessed.
Results
The most common cumulative cause of TKA failure was infection (38%) followed by loosening (33%), wear (13%), instability (7%), and stiffness (3%). However, the incidence of infections has declined over the past 5 years, whereas that of loosening has increased and exceeds that of infection in the more recent 3 years. Young age (odds ratio [OR] per 10 years of age increase, 0.41; 95% confidence interval [CI], 0.37–0.49) and male sex (OR, 1.88; 95% CI, 1.42–2.49) were associated with an increased risk of failure. The percentage of revision TKAs in all primary and revision TKAs remained at approximately 3%, but the annual numbers of revision TKAs in the more recent 3 years increased from that of 2008 by more than 23%.
Conclusions
Despite a recent remarkable increase in TKA use and differences in demographic features, the causes and risk factors for failures in Korea were similar to those of Western countries. Infection was the most common cause of failure, but loosening has emerged as the most common cause in more recent years, which would prompt us to scrutinize the cause and solution to reduce it.
Level of Evidence
Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-013-3252-8
PMCID: PMC3889422  PMID: 23982406
14.  Time trends in the Characteristics of Patients Undergoing Primary Total Knee Arthroplasty 
Arthritis care & research  2014;66(6):897-906.
Objective
To study the time-trends in socio-demographic and clinical characteristics of patients undergoing primary total knee arthroplasty (TKA).
Methods
We used the Mayo Clinic Total Joint Registry to examine the time-trends in patient demographics (body mass index [BMI], age), underlying diagnosis, medical (Deyo-Charlson index) and psychological comorbidity (anxiety, depression) and examination findings of primary TKA patients from 1993–2005. We used chi-square test and analysis of variance.
Results
7,229 patients constituted the primary TKA cohort; 55% were women. The mean age decreased by 1.3 years (69.3 to 68.0), BMI increased by 1.7 kg/m2 (30.1 to 31.8) and Deyo-Charlson index increased by 36% (1.1 to 1.5) over the 13-year study period (p<0.001 for all). Compared to 1993–95, significantly more patients (by 2–3 times) in 2002–05 had (p<0.001 for all): BMI ≥40, 4.8% vs. 10.6%; age <50, 2.9% vs. 5.2%; Deyo-Charlson index of ≥3, 12% vs. 22.3%; depression, 4.1% vs. 14.8%; anxiety, 4.1% vs. 8.9%; and a significantly fewer had an underlying diagnosis of rheumatoid/inflammatory arthritis, 6.4% vs. 1.5%. Compared to 1993–95, significant reductions were noted in 2002–05 for the physical examination findings of (p<0.001 for all): knee joint effusion, anterior-posterior knee instability, medial-lateral knee instability, moderate-severe knee synovitis, severe limp, fair or poor muscle strength and absent peripheral pulses.
Conclusions
In this large U.S. total joint registry study, we found significant time-trends in patient characteristics, diagnosis, comorbidity and knee/limb examination findings in primary TKA patients over 13-years. These secular trends should be taken into account when comparing outcomes over time and in policy-making decisions.
doi:10.1002/acr.22233
PMCID: PMC4151514  PMID: 24249702
Total knee replacement; time trends; arthroplasty; joint replacement; diagnosis; obesity; comorbidity; osteoarthritis
15.  GENDER AND SURGICAL OUTCOMES AND MORTALITY AFTER PRIMARY TOTAL KNEE ARTHROPLASTY: A RISK-ADJUSTED ANALYSIS 
Arthritis care & research  2013;65(7):10.1002/acr.21953.
Objective
Total knee arthroplasty (TKA) is a widely utilized and an effective treatment option for end-stage knee OA. Knee OA is more prevalent among women compared to men, but there are limited data on gender differences in surgical outcomes after total knee arthroplasty.
Methods
Our sample consisted of all primary TKA’s performed in the State of Pennsylvania during the fiscal year 2002. We used ICD-9 codes to identify major complications and surgical revision. We used mixed effects logistic regression models to examine the associations between gender and all-cause mortality, readmissions, and major surgical complications. We used proportional hazards model to assess the risk of surgical revision after index arthroplasty. We adjusted for race, age, hospital teaching status, hospital procedure volume, insurance status and risk of mortality.
Results
In 17,994 primary TKA’s, there were 46 deaths at 30-days and 220 at one-year. Compared to women, men had higher adjusted odds of one-year mortality (Odds Ratio (OR)=1.48; 95% CI=1.13–1.94) after primary TKA. The overall odds of most major 30-day complications did not differ by gender, except surgical wound infections, which were higher in men compared to women (OR= 1.31; 95% CI=1.08–1.60); 30-day readmission was higher in men (OR=1.25; 95% CI=1.10–1.43). Men had significantly higher rates of index knee arthroplasty revision at 5-years (hazard ratio= 1.20; 95% CI=1.05–1.36) compared to women.
Conclusion
Higher rates of mortality, hospital readmissions, revision surgery and wound infections in men undergoing elective TKA, compared to women, indicates gender disparity in these outcomes.
doi:10.1002/acr.21953
PMCID: PMC3850181  PMID: 23335560
16.  What Are the Causes of Revision Total Knee Arthroplasty in Japan? 
Background
There is limited information regarding the cause of revision TKA in Asia, especially Japan. Owing to differences in patient backgrounds and lifestyles, the modes of TKA failures in Asia may differ from those in Western countries.
Questions/purposes
We therefore determined (1) causes of revision TKA in a cohort of Japanese patients with revision TKA and (2) whether patient demographic features and underlying diagnosis of primary TKA are associated with the causes of revision TKA.
Methods
We assessed all revision TKA procedures performed at five major centers in Hokkaido from 2006 to 2011 for the causes of failures. Demographic data and underlying diagnosis for index primary TKA of the revision cases were compared to those of randomly selected primary TKAs during the same period.
Results
One hundred forty revision TKAs and 4047 primary TKAs were performed at the five centers, indicating a revision burden of 3.3%. The most common cause of revision TKA was mechanical loosening (40%) followed by infection (24%), wear/osteolysis (9%), instability (9%), implant failure (6%), periprosthetic fracture (4%), and other reasons (8%). The mean age of patients with periprosthetic fracture was older (77 versus 72 years) and the male proportion in patients with infection was higher (33% versus 19%) than those of patients in the primary TKA group. There was no difference in BMI between primary TKAs and any type of revision TKA except other causes.
Conclusions
The revision burden at the five referral centers in Hokkaido was 3.3%, and the most common cause of revision TKA was mechanical loosening followed by infection. Demographic data such as age and sex might be associated with particular causes of revision TKA.
doi:10.1007/s11999-013-2820-2
PMCID: PMC3613556  PMID: 23385774
17.  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.
doi:10.1016/j.arth.2013.04.003
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
18.  2- to 9-year outcome of stemmed total knee arthroplasty 
Acta Orthopaedica  2014;85(6):609-613.
Background and purpose —
There is an increase in demand for primary and revision total knee joint procedures. We studied implant survival and functional outcome of patients operated with a constrained condylar knee (CCK) or a rotating hinge implant (RH) as a primary or a revision total knee arthoplasty (TKA).
Patients and methods —
We evaluated clinically and radiographically 65 surgical procedures with a mean follow-up time of 5 (2–9) years (40 CCK and 25 RH). There were 24 primary TKAs—due to instability—and 41 revision TKAs, mostly due to aseptic loosening. Mean age at the index operation was 68 (31–88) years.
Results —
Overall, there were 12 failures, including 8 reoperations due to deep infection. The overall 5-year survival rate with reoperation as the endpoint was 82% (95% CI: 72–99). Radiolucent lines on either the femoral or the tibial side were seen in 36 cases. When comparing the cases that were operated as a primary TKA or as a revision TKA, function, health-related quality of life, and survival were similar. However, after primary TKA the patients generally had less pain and a higher proportion of patients were very satisfied or satisfied.
Interpretation —
Although a high rate of severe complications was observed, most patients improved in function after surgery regardless of whether it was a primary or a revision TKA. We found narrow radiolucent lines—mainly on the tibial side—in nearly half of the cases, but none of the implants were loose radiographically. Overall patient satisfaction and health-related quality of life were high, and a minority had problems with persistent pain.
doi:10.3109/17453674.2014.962411
PMCID: PMC4259026  PMID: 25238436
19.  Comparision of blood loss between computer assisted and conventional total knee arthroplasty 
Indian Journal of Orthopaedics  2013;47(1):63-66.
Background:
Bleeding during total knee arthroplasty (TKA) can cause significant morbidity and mortality. One proposed benefit of computer assisted TKA is decreased bleeding as the femoral canal is not invaded. This study assessed blood loss between computer assisted surgery (CAS) and conventional TKA.
Materials and Methods:
73 consecutive patients (37 males, 36 females) underwent primary TKA between 2006 and 2009. Thirty eight patients underwent navigated TKA and 35 underwent conventional TKA for symptomatic osteoarthritis of the knee. These patients were matched for age, gender, and body mass index (BMI). Average age was 70.3 years (range 47-91 years). Mean BMI was 30 (range 17-49). Average preoperative hemoglobin was 13.26 g/dL (range 8.7-18.4 g/dL) in the navigated group and 13.47 g/dL (range 9.6-15.8 g/dL) in the conventional group (P = 0.9). Average tourniquet time was 110 min (range 90-150 min) in the navigated group and 96.7 min (range 60-145 min) in the conventional group (P = 0.77).
Results:
Average postoperative hemoglobin in the navigated group was 10.34 g/dL (range 7.5-14.8 g/dL) and in the conventional group was 10.03 g/dL (range 7.5-12.2 g/dL) (P = 0.17). Six patients in both groups required blood transfusions. The mean drain collection was 599 mL (range 150-1370 mL) in the navigated group and 562 mL (range 750-1000 mL) in the conventional group (P = 0.1724). These results suggest that there is no significant reduction in blood loss in CAS TKA.
Conclusion:
These results suggest that there is no significant difference in blood loss in CAS TKA and conventional TKA. This study also highlights the heterogeneity of methods used in studies related to CAS TKA. We believe that there is a need for a large multicenter prospective randomized controlled trial to be performed before a consensus can be reached on the influence of CAS techniques on blood loss during primary TKA.
doi:10.4103/0019-5413.106906
PMCID: PMC3601237  PMID: 23532765
Blood loss; computer navigated total knee arthroplasty; conventional total knee arthroplasty
20.  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.
Objective
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).
Methods
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).
Results
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).
Conclusion
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.
doi:10.1002/acr.22090
PMCID: PMC3855298  PMID: 23925956
Total knee replacement; arthroplasty; joint replacement; patient-reported outcomes; osteoarthritis; rheumatoid arthritis
21.  Most patients gain weight in the 2 years after total knee arthroplasty: comparison to a healthy control group 
Summary
Objective
While joint arthroplasty improves the functional ability of persons with severe knee osteoarthritis (OA), the long-term effects of surgical intervention on body mass have not been evaluated. The objective of this study was to determine if a reduction in body mass index (BMI) was present following unilateral total knee arthroplasty (TKA) compared to an age-matched healthy control group who did not have surgery.
Method
One hundred and six adults with unilateral, end-stage knee OA and thirty-one persons without knee pain participated in the prospective longitudinal study. Subjects with OA underwent primary unilateral TKA and received post-operative out-patient physical therapy. Height, weight, quadriceps strength and self-perceived functional ability were measured at baseline and at a 2-year follow-up.
Results
There was a significant interaction effect between body mass over time and subject group (P = 0.017). BMI showed a significant increase over 2 years for the surgical group (P < 0.001), but not for the control group (P = 0.842). Sixty-six percent of the persons in the surgical group gained weight over the 2 years with an average weight gain of 6.4 kg, or 14 pounds, 2 years after their initial physical therapy visit. Educational level, marital status, income level and activity level prior to surgery were not related to post-surgical weight gain.
Conclusion
The majority of subjects gain weight after surgery and this cannot be attributed to the effects of aging. Weight gain after TKA should be treated as an independent concern and management of orthopedic impairments will not result in weight loss. Post-operative care should include access to nutrition or weight management professionals in addition to medical and physical therapy services.
doi:10.1016/j.joca.2009.12.005
PMCID: PMC2846226  PMID: 20060949
Osteoarthritis; Knee; Arthroplasty; Weight gain; Outcomes assessment
22.  Biofeedback to Promote Movement Symmetry After Total Knee Arthroplasty: A Feasibility Study 
STUDY DESIGN
Prospective analysis of a longitudinal cohort with an embedded comparison group at a single time point.
OBJECTIVES
To determine the feasibility and effectiveness of an outpatient rehabilitation protocol that includes movement symmetry biofeedback on functional and biomechanical outcomes after total knee arthroplasty (TKA).
BACKGROUND
TKA reduces pain and improves functional ability, but many patients experience strength deficits and movement abnormalities in the operated limb, despite outpatient rehabilitation. These asymmetries increase load on the nonoperated limb, and greater asymmetry is related to worse functional outcomes.
METHODS
Biomechanical and functional metrics were assessed 2 to 3 weeks prior to TKA, at discharge from outpatient physical therapy, and 6 months after TKA in 11 patients (9 men, 2 women; mean ± SD age, 61.4 ± 5.8 years; body mass index, 33.1 ± 5.4 kg/m2) who received 6 to 8 weeks of outpatient physical therapy that included specialized symmetry training. Six-month outcomes were compared to a control group, matched by age, body mass index, and sex (9 men, 2 women; mean ± SD age, 61.8 ± 5 years; body mass index, 34.3 ± 5.1 kg/m2), that did not receive specialized symmetry retraining.
RESULTS
Of the 11 patients who received added symmetry training, 9 demonstrated clinically meaningful improvements that exceeded the minimal detectable change for all performance-based functional tests at 6 months post-TKA compared to pre-TKA. Six months after TKA, when walking, patients who underwent symmetry retraining had greater knee extension during midstance and had mean sagittal knee moments that were more symmetrical, biphasic, and more representative of normal knee kinetics compared to patients who did not undergo symmetry training. No patients experienced adverse events as the result of the protocol.
CONCLUSION
Adding symmetry retraining to postoperative protocols is clinically viable, safe, and may have additional benefits compared to rehabilitation protocols that focus on range of motion, strength, and return to independence.
doi:10.2519/jospt.2013.4657
PMCID: PMC4072454  PMID: 23892267
biomechanics; gait; joint replacement; sit-to-stand
23.  Comparative Demographics, ROM, and Function After TKA in Chinese, Malays, and Indians 
Background
There is marked racial disparity in TKA use rates, demographics, and outcomes between white and Afro-Caribbean Americans. Comparative studies of ethnicity in patients undergoing TKAs have been mostly in American populations with an underrepresentation of Asian groups. It is unclear whether these disparities exist in Chinese, Malays, and Indians.
Questions/purposes
We therefore determined whether (1) TKA use; (2) demographics and preoperative statuses; and (3) functional outcomes at 2 years after TKA differed among three ethnic groups, namely, Chinese, Malays, and Indians who underwent TKA.
Methods
From our hospital joint registry we identified 5332 patients who had a primary TKA from 2004 to 2009. The cohort was stratified by race and subsequently compared for demographics, preoperative knee ROM, and deformity. At the second postoperative year we determined Knee Society scores, Oxford knee scores, and obtained SF-36 health questionnaires.
Results
Six percent more Chinese patients underwent TKAs compared with Malays or Indians. Malays were operated on at a younger age with a higher body mass index. Chinese patients had more severe preoperative varus deformity. There were no major differences in joint ROM in all races. For Knee Society, Oxford knee, and SF-36 scores, Chinese patients had consistently higher preoperative and postoperative scores. Malays presented with the lowest preoperative scores but had the greatest improvement in scores at followup with postoperative scores similar to Chinese counterparts. Indians had the lowest postoperative scores and worst improvement of all
Conclusions
The variations in demographics, preoperative statuses, and subsequent postoperative outcomes between the races should be considered when comparing TKA outcome studies in Asian populations.
Level of Evidence
Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2776-7
PMCID: PMC3613548  PMID: 23299954
24.  Factors Affecting Outcome after Total Knee Arthroplasty in Patients with Diabetes Mellitus 
Yonsei Medical Journal  2008;49(1):129-137.
Purpose
To compare the clinical outcome and complications following total knee arthroplasty (TKA) in diabetic and non-diabetic patients, and to identify diabetes-related risk factors for negative outcomes.
Materials and Methods
222 primary TKAs in patients with diabetes were evaluated using Knee Society scores and Hospital for Special Surgery score. Postoperative complications were reviewed retrospectively. The mean follow-up was 53.2 months. The effect of diabetesrelated factors and comparison with a matched control group were analyzed statistically.
Results
Significant improvements were noted in all the scores after TKA (p < 0.05). There was no statistical difference in clinical sores between the diabetic and non-diabetic patients. In multivariate analysis associating age, gender and body mass index with pain and knee score at the latest follow-up, the average knee scores in normal and overweight group were found to be significantly higher than those in the obese group. The diabetic patients had an increased overall incidence of postoperative complications (17.6%) compared with the control group (8.1%) (p < 0.05). Particularly, the rate of wound complications such as skin necrosis, bulla formation or erythema with drainage was higher in the diabetic group (p < 0.05). Diabetes-related factors did not influence the incidence of complications. Associated diseases were the only significant risk factors correlated with wound complications and meniscal bearing dislodgement.
Conclusion
Patients with diabetes can benefit from TKA, even though diabetic patients are at an increased risk for overall postoperative and wound complications. Preoperative factors such as obesity and associated diseases may adversely affect the clinical outcome of TKA in diabetic patients.
doi:10.3349/ymj.2008.49.1.129
PMCID: PMC2615258  PMID: 18306479
Diabetes mellitus; total knee arthroplasty; clinical outcome; complication; risk factor
25.  Unicompartmental Versus Total Knee Arthroplasty Database Analysis: Is There a Winner? 
Background
TKA and unicompartmental knee arthroplasty (UKA) are both utilized to treat unicompartmental knee arthrosis. While some surgeons assume UKA provides better function than TKA, this assumption is based on greater final outcome scores rather than on change in scores and many patients with UKA have higher preoperative scores.
Questions/purposes
We therefore asked whether TKA would demonstrate (1) better change in clinical outcome scores from preoperative to postoperative states and (2) better survivorship than UKA.
Methods
We evaluated 4087 patients with 5606 TKAs and 179 patients with 279 UKAs performed between 1978 and 2009. Patients with TKA were older and heavier than patients with UKA (mean age, 68 versus 66 years; mean BMI, 32 versus 29). We compared preoperative, latest postoperative, and change in Knee Society Clinical Rating System (KSCRS), SF-12, and WOMAC scores. Minimum followup was 2 years (UKA: mean, 7 years; range, 2.0–23 years; TKA: mean, 6.5 years; range, 2.0–33 years). Preoperative outcome measure scores (WOMAC, SF-12, KSCRS) were higher in the UKA group.
Results
Patients with UKA had higher postoperative KSCRS and SF-12 mental scores. Changes in score for all WOMAC domains were similar between groups. Total KSCRS changes in score were similar between groups, although patients with TKA had higher knee scores (49 versus 43) but lower function scores than UKA (21 versus 26). Cumulative revision rate was higher for UKA than for TKA (13% versus 7%). Kaplan-Meier survivorship at 5 and 10 years was 95% and 90%, respectively, for UKA and 98% and 95%, respectively, for TKA.
Conclusions
While patients with UKA had higher pre- and postoperative scores than patients with TKA, the changes in scores were similar in both groups and survival appeared higher in patients with TKA.
Level of Evidence
Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-011-2144-z
PMCID: PMC3237994  PMID: 22038173

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