Risks and Benefits of Simultaneous Bilateral Total Knee Arthroplasty

Complications following bilateral simultaneous versus staged total knee arthroplasty in the Japanese population: a propensity-matched case-control study

Although bilateral simultaneous total knee arthroplasty (BSTKA) is an effective treatment for bilateral knee osteoarthritis, safety concerns and lack of precise patient selection criteria persist. This study aimed to determine the differences in perioperative parameters and complication rates between BSTKA and staged TKA in the Japanese population. We retrospectively reviewed 531 patients who underwent BSTKA or staged TKA between 2012 and 2021. Propensity score matching, performed on a 1:1 nearest neighbor basis for age, BMI, diagnosis, ASA score, and age-adjusted Charlson Comorbidity Index, yielded matched cohorts of 94 patients (188 knees) for each group. Outcome measures included operative time, perioperative blood loss, length of hospital stay, and nonmechanical complications after surgery. The BSTKA group had a shorter median operative time and hospital stay (111 min and 16 days) than the staged TKA group (159 min and 33 days) (p < 0.001). Overall complication rates were higher in the BSTKA group than in the staged TKA group (26% vs. 13%, p = 0.026), with anemia requiring transfusion being the most common. Cardiovascular complications were more frequent in the BSTKA group (4.3% vs. 0%, p = 0.043). These findings emphasize the importance of careful patient selection and risk assessment when considering BSTKA.

Mental Robustness May Be Associated With Improved Physical Function in Bilateral Total Knee Arthroplasty Patients

BACKGROUND

In accordance with the high incidence of bilateral knee osteoarthritis, many patients have undergone bilateral total knee arthroplasty (BTKA). Whether patients undergo bilateral procedures in a staged or simultaneous fashion, the physical and mental burden of undergoing 2 major orthopedic procedures is considerable. The aims of this study were to (1) investigate differences between minimal clinically important difference (MCID) achievement between staged versus simultaneous BTKA, and (2) identify the patient variables, specifically mental scores, that were associated with MCID achievement in patients undergoing BTKA.

METHODS

Simultaneous and staged BTKA patients within a single health care network from 2016 to 2021 were retrospectively reviewed. Patient demographics, surgery details, and Patient-Reported Outcome Measurement Information System Physical Function Short Forms 10a (PROMIS PF10a), PROMIS Mental scores, and Knee Disability Osteoarthritis Outcome Scores (KOOS) were reviewed. Preoperative and postoperative patient-reported outcome measures were collected before the first total knee arthroplasty (TKA) and after the second TKA, respectively, in staged BTKA patients. The final cohort consisted of 249 patients, with an average age of 66 years (range, 21 to 87), 63% women, and an average body mass index of 32 (range, 20 to 52), at a mean follow-up of 1.1 years (range, 0.5 to 2.4). Multivariate regressions were performed on MCID PF10a and KOOS achievement, as well as whether the BTKA was performed simultaneously versus staged.

RESULTS

A preoperative PROMIS Mental score in the upper 2 quartiles was associated with MCID PF10a achievement in BTKA. Men and surgeries performed at an Academic Medical Center were negatively associated with the achievement of MCID KOOS. Interestingly, those who underwent simultaneous BTKA were less likely to achieve MCID KOOS than those who underwent a staged BTKA.

CONCLUSIONS

Preoperative mental robustness may be positively associated with improved physical function outcome in BTKA patients.

No differences in terms of complications, readmissions, reoperations, and patient-reported outcomes in simultaneous bilateral versus staged bilateral total knee arthroplasty in selected patients

BACKGROUND

The safety and the clinical success of simultaneous bilateral total knee arthroplasty (BTKA) is controversial. The aim of this study was to compare complications and patient-reported outcomes following simultaneous BTKA (simBTKA) versus staged BKTA (staBTKA) in patients affected by bilateral symptomatic end-stage knee osteoarthritis (OA).

METHODS

Data from patients who underwent simBTKA or staBTKA at a single institution from January 2017 to December 2020, with a minimum 1-year follow up period were retrospectively collected. Differences in terms of complications and clinical success were compared among the simBTKA and staBTKA patient groups. Alpha was set at 0.05.

RESULTS

A total of 173 patients were included in this study. The results revealed no statistically significant differences between the two groups in terms of mortality, revision rate, readmission rate, local and systemic complications and patient-reported outcomes. SimBTKA group had a shorter operating room time (96 (73-119) vs. 195 (159-227); P < 0.0001), and length of hospital stay (4 (3-5) vs. 7 (6-9); P < 0.0001) compared with the staBTKA group.

CONCLUSIONS

SimBTKA performed in a selected patient population at a high-volume center can be considered comparable to staBTKA in terms of safety, postoperative complications, 30-day readmissions and patient satisfaction. Consequently, reduced operating room time and hospital stay renders simBTKA a cost-effective and advantageous option, not only for patients, but also for healthcare institutes. Furthermore, the current study also highlights the importance of correct patient selection based on clinical preoperative characteristics.

A nationwide comparison of staggered and simultaneous bilateral knee arthroplasty during a single hospitalization: Trends, risks and benefits

Background

We aimed to: (1) perform a nationwide trend analysis of staggered and simultaneous bilateral knee arthroplasty (KA); (2) investigate patient demographics and hospital characteristics in two groups; and (3) compare the outcomes of two groups with a focus on complications, length of stay (LOS) and hospitalization costs.

Methods

Utilizing the Hospital Quality Monitoring System, we included patients who underwent bilateral KA during a single hospitalization between 2013 and 2019. Patient demographics and hospital characteristics were compared between two groups. Outcomes were compared between propensity-score matched groups using logistic and linear regression.

Results

During the study period, 6291 staggered bilateral KA and 6284 simultaneous bilateral KA were performed. From 2013 to 2019, the proportion of staggered bilateral KA increased from 32.74% to 59.08%. Patients who were older, were single, had more comorbidities and had a non-osteoarthritis indication for surgery tended to receive staggered bilateral KA. Compared with 3327 propensity-score matched patients undergoing simultaneous bilateral KA, patients undergoing staggered bilateral KA were associated with a significantly lower incidence of wound infection (odds ratio [OR] ​= ​0.22; 95% confidence interval [CI], 0.07–0.65), and readmission within 30 days (OR ​= ​0.73; 95%CI, 0.54–0.99) and 90 days (OR ​= ​0.70; 95%CI, 0.55–0.89). However, staggered bilateral KA had higher odds of blood transfusion (OR ​= ​1.20; 95%CI, 1.02–1.40) and deep venous thrombosis (DVT) (OR ​= ​2.62; 95%CI, 1.82–3.98). Moreover, staggered bilateral KA can lead to higher costs (108,316.21 Chinese yuan [CNY] vs 103,367.60 CNY) and longer LOS (17.29 days vs 12.18 days) than simultaneous bilateral KA.

Conclusion

Our study indicates that staggered bilateral KA has become more common than simultaneous bilateral KA in China. Compared to simultaneous bilateral KA, staggered bilateral KA was associated with a lower incidence of wound infection and readmission. Staggered bilateral KA may be an alternative for patients who can't tolerate simultaneous surgery.

The translational potential of this article: Our study indicates that staggered bilateral KA is a safe and economical option for elderly patients who require bilateral KA but are at high clinical risk. The rising proportion of staggered bilateral KA will be a new trend in bilateral KA.

Trends of Obese and Morbidly Obese Patients in Same-Day Bilateral Total Knee Arthroplasty from 2009 to 2016

As obesity in the United States increases, the proportion of obese and morbidly obese patients undergoing same-day bilateral total knee arthroplasty (sd-BTKA) remains unknown. Therefore, this study analyzed: (1) incidence, (2) patient demographics, (3) patient course, and (4) patient outcomes in obese and morbidly obese patients undergoing sd-BTKA in the United States from 2009 to 2016. The National Inpatient Sample was queried for all sd-BTKA patients from 2009 to 2016, yielding 39,901 obese and 20,394 morbidly obese patients. Analyzed variables included overall incidence, age, length of stay (LOS), sex, race, payer, Charlson comorbidity index (CCI) status, disposition, complications, location/teaching status, region of hospital, costs, and charges. Categorical variables were evaluated with chi-square analysis, while continuous variables were analyzed by Student's t-tests. Overall, the number of sd-BTKAs decreased over the study period, although the proportion of both obese and morbidly obese patients increased (p < 0.001 for all). The most common CCI status, 3 + , decreased in proportion for both groups (p < 0.001 for all). Hospital costs decreased and charges increased for both groups (p < 0.001 for all). Mean LOS decreased and patients were most commonly discharged to skilled nursing facilities, although these proportions decreased (p < 0.001 for all). Respiratory failures (p < 0.001 for all) increased for both groups, while proportion of deep vein thromboses and hematomas/seromas (p < 0.001 for all) increased for obese patients and proportion of pulmonary emboli (p < 0.001) increased for morbidly obese patients. The results of this study appear to portray improving optimization and patient selection of higher body mass index (BMI) individuals undergoing this procedure. More information is needed comparing the safety of the sd-BTKA across patients of all BMI groups.

Simultaneous Bilateral Total Knee Arthroplasty Is Associated With Shorter Length of Stay but Increased Mortality Compared With Staged Bilateral Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Primary total knee arthroplasty (TKA) is associated with high patient satisfaction. However, controversy remains regarding the safety and efficacy of conducting simultaneous bilateral (simBTKA) versus staged bilateral TKA (staBTKA). The objective of this systematic review and meta-analysis was to evaluate the current evidence for simBTKA versus staBTKA and compare clinical outcomes including mortality, complications and length of stay (LOS).

METHODS

A search was performed of PubMed, MEDLINE, EMBASE and Cochrane central databases between January 2000 and March 2020. Search terms included "simultaneous," "staged," and "bilateral TKA." Inclusion criteria comprised studies comparing outcomes of simBTKA versus staBTKA. Quality of included studies was assessed and meta-analyses of pooled data was conducted.

RESULTS

29 articles published between 2001 and 2020 were included in qualitative synthesis from 927 potentially relevant titles, comprising 257,284 patients. 104,207 patients underwent simBTKA and 153,632 patients underwent staBTKA. simBTKA was associated with significantly increased 90-day mortality rate (P < .00001, OR 2.24, 95% CI 1.79-2.81), increased incidence of pulmonary embolism (P < .00001, OR 1.69, 95% CI 1.51-1.89), venous thrombosis (P < .00001, OR 1.33, 95% CI 1.23-1.43), and neurological complications (P = .002, OR 1.42, 95% CI 1.13-1.77). Incidence of superficial and deep infection was significantly increased with staBTKA (P = .02, P < .00001 respectively). Revision rate within one year was equivocal. Mean LOS was 2.1 days shorter for simBTKA.

CONCLUSION

SimBTKA was associated with decreased incidence of infection and LOS but increased incidence of 90-day mortality, venous thromboembolism and neurological complications. Revision rates were equivocal. Patients should be selected and counseled based on the risks respective to each strategy.

Comparing Sequential vs Simultaneous Tourniquet Inflation in Bilateral Total Knee Arthroplasty

Background

There is little evidence on outcomes of tourniquet use during bilateral total knee arthroplasty (BTKA). Tourniquet use in BTKA effects postoperative outcomes and efficiency inside the operating room. This study evaluates the safety and efficacy of simultaneous tourniquet inflation in BTKA.

Materials and Methods

A retrospective review was performed on BTKA patients between March 2013 and May 2018. A total of 285 patients were divided into 2 cohorts. Patients in the simultaneous cohort had concomitant elevation of both tourniquets, but the sequential cohort did not. Perioperative variables were collected, and postoperative complications were tracked for a minimum of 90 days. Patients followed a uniform postoperative protocol. Complications were grouped by category to increase statistical power and compared using a noninferiority test. “Clinically noninferior” was defined as a margin ≤5%.

Results

The simultaneous cohort had significantly (P < .05) higher American Society of Anesthesiologists class and smokers. Tourniquet time, delta hemoglobin, and surgical time were significantly lower. For the complication categories of “Any Thrombotic Event”, “Respiratory”, and “Soft Tissue/Wound”, the difference in occurrence rates was no more than 2.8%, 2.8%, and 5.2% between cohorts, respectively. The “Cardiovascular (non-MI)” group was no more than 9.3% different, that is, authors are 95% confident that 3 of 4 complication categories meet the clinically noninferior threshold.

Conclusion

The study demonstrates the noninferiority of simultaneous as compared to sequential tourniquet inflation in BTKA. Patients with cardiac history may need sequential inflation or staged TKA. The information presented in the study assists surgeons in safely and efficiently performing BTKA.

Same-Day Bilateral Total Knee Arthroplasty: Incidence and Perioperative Outcome Trends from 2009 to 2016

BACKGROUND

Same-day bilateral total knee arthroplasty (BiTKA) is a controversial topic in orthopedics, prompting a consensus statement to be released by national experts. To date, no studies have evaluated the trends of this method since these recommendations. This study utilized a national database to evaluate: 1) incidence; 2) patient characteristics; 3) hospital characteristics; and 4) inpatient course for same-day BiTKAs in the United States from 2009 to 2016.

METHOD

The National Inpatient Sample database was queried for individuals undergoing same-day BiTKAs, yielding 245,138 patients. Patient demographics included age, sex, race, obesity status and Charlson Comorbidity Index (CCI) score. Hospital characteristics consisted of location/teaching status, geographic region, charges, and costs. Inpatient course included length of stay, discharge disposition, and complications.

RESULTS

Same-day BiTKA incidence decreased from 5.6% to 4.0% over the study (p < 0.001). Decreases in patient age and female proportion (p < 0.001 for both) were seen, while African American and Hispanic patients increased (p < 0.001), as did obese patient proportions (p < 0.001). Patients with CCI scores of 2 increased, while those with ≥3 decreased (p < 0.001). Hospital charges increased, while costs decreased (p < 0.001 for both). Length of stay following same-day BiTKA decreased (p < 0.001) and routine home discharges increased (p < 0.001). Most inpatient complications decreased, although the percentage of mechanical complications and respiratory failures increased (p < 0.01 for all).

CONCLUSIONS

During the study period, younger patients with fewer comorbidities underwent BiTKAs, which likely resulted from improved patient assessment and management. Future investigations should include an evaluation of long-term complications and outcomes in certain patient populations for this procedure.

Risk of chronic opioid use after simultaneous versus staged bilateral knee arthroplasty

BACKGROUND

Several studies have identified excess risk associated with undergoing simultaneous (compared with unilateral or staged) bilateral total knee arthroplasty (BTKA). However, few have addressed subsequent chronic opioid use. Given the substantial morbidity and mortality associated with prolonged opioid use, we evaluated the incidence of postoperative chronic opioid use following simultaneous versus staged BTKA, based on the different timing strategies of staged procedures.

METHODS

In this retrospective cohort study, patients who underwent BTKA procedures (2012-2016; Truven Health MarketScan; n=14 407) were classified as having undergone simultaneous or staged BTKA (<3 months, 3-6 months or 6-12 months apart). Outcomes were postoperative chronic opioid use and oral morphine equivalents prescribed on discharge. Multivariable regression models measured associations between type/timing of BTKA and outcomes. ORs and 95% CIs were reported.

RESULTS

Unadjusted frequency of chronic opioid use did not differ between groups, (Simultaneous: 11.3%, staged <3 months: 10.7%, staged 3-6 months: 11.7%, staged >6 months: 10.2%; p=0.247). In an adjusted model, there was no significant difference in the odds of becoming chronic opioid users between staged and simultaneous BTKA (staged <3 months OR 1.03, 95% CI 0.88 to 1.21/staged 3-6 months OR 0.94, 95% CI 0.79 to 1.12/staged >6 months OR 0.96, 95% CI 0.82 to 1.13; p=0.755). Patients undergoing staged BTKAs <6 months apart (compared with simultaneous) were prescribed slightly greater oral morphine equivalents on hospital discharge (staged <3 months 6% increase, 95% CI 3% to 10%; staged 3-6 months 4%, 95% CI 1% to 8%; p=0.002).

CONCLUSION

Although patients undergoing staged BTKA <6 months apart were prescribed greater quantities of opioids on discharge, there was no significant difference in the odds of postoperative chronic opioid use compared with simultaneous BTKA. The timing of BTKA procedures does not appear to influence the likelihood of postoperative chronic opioid dependence.

Obesity and its effect on outcomes in same-day bilateral total knee arthroplasty

Background

The niche surgery of same-day bilateral total knee arthroplasty (sd-BTKA) continues to create debate amongst specialists in arthroplasty. To date, there is a significant lack of literature on obese patients undergoing sd-BTKA, and no study has evaluated outcomes of this procedure when compared to non-obese patients. Therefore, this study will perform a retrospective analysis to compare (I) incidence, (II) demographics, and (III) complications of sd-BTKA in non-obese, obese, and morbidly obese patients in the United States from 2009 to 2016.

Methods

The National Inpatient Sample (NIS) database was queried for all individuals that underwent sd-BTKA from 2009 to 2016. This returned 184,844 non-obese patients, 39,901 obese patients, and 20,394 morbidly obese patients. Analyzed variables included mean age, mean length of stay (LOS), race, payer, age-adjusted Charlson Comorbidity Index score, discharge disposition, hospital charges, hospital costs, and complications. Chi-square analyses and analyses of variance were utilized to assess categorical and continuous variables, respectively.

Results

Non-obese patients most commonly underwent sd-BTKA over the course of the study. As weight status increased, mean age decreased and the proportion of females, LOS, hospital charges and costs, and proportion of discharges to skilled nursing facilities increased. Regression analysis demonstrated obese and morbidly obese cohorts were at an overall increased odds for experiencing complications. Specifically, obese patients were at increased risk for pulmonary emboli, periprosthetic joint infections, and respiratory failures, while morbidly obese patients are at increased risk for pulmonary emboli, respiratory failures, and urinary tract infections.

Conclusions

Surgeons should thoroughly evaluate the risks and benefits of performing sd-BTKA on obese and morbidly obese patients, as both confer higher overall complication rates and increased length of stay. More research is necessary to characterize the cost analysis of this procedure, as health care models continue to transition to more cost-effective procedures.

Long-Term Implant Survivorship and Modes of Failure in Simultaneous Concurrent Bilateral Total Knee Arthroplasty

BACKGROUND

There is limited evidence describing long-term implant survivorship and modes of failure in simultaneous concurrent bilateral total knee arthroplasty (TKA).

METHODS

We performed a retrospective review of 266 consecutive patients (532 knees) who underwent simultaneous concurrent bilateral TKA. We reviewed medical records for preoperative characteristics, perioperative complications, and revision surgeries. The primary outcome was TKA survivorship. Secondary outcomes included indication and type of revision surgery. We used the Kaplan-Meier method to estimate survivorship and characterize risk of revision up to 20 years post-TKA.

RESULTS

Our cohort had median follow-up of 9.8 years (interquartile range, 3.9-15.9). Forty-four patients (17%) underwent revision. Revision was more common among younger and male patients. The cumulative incidence of first-time revision per knee (n = 532) was 1.27 per 100 component-years. Implant survival was 99% (confidence interval, 97%-99%) at 5 years, 92% (89%-95%) at 10 years, 83% (77%-87%) at 15 years, and 62% (50%-73%) at 20 years. Five and 10-year survivorship compared favorably to estimates of TKA survivorship in the literature. The cumulative incidence of revision surgery per patient was 1.91 per 100 component-years. Implant survival at 5-, 10-, 15-, and 20-year time points was 96% (CI, 92%-98%), 84% (77%-89%), 71% (62%-79%), and 59% (46%-70%), respectively. Aseptic loosening (40%), polyethylene wear (34%), and infection (11%) were the most common indications for revision.

CONCLUSION

Simultaneous concurrent bilateral TKA is associated with a higher risk of reoperation for the patient when both knees are evaluated but similar implant survivorship to the literature when each knee was evaluated in isolation.

Comparing the Safety and Outcome of Simultaneous and Staged Bilateral Total Knee Arthroplasty in Contemporary Practice: A Systematic Review of the Literature

BACKGROUND

Although a variety of studies have assessed the outcomes of simultaneous bilateral total knee arthroplasty (BTKA) and staged BTKA, there remains no definitive conclusion regarding the superiority of one technique in terms of safety.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried utilizing keywords pertinent to BTKA, simultaneous and staged, and clinical or functional outcomes. In order to examine the contemporary relevant literature, studies published prior to 2009 were excluded from our search.

RESULTS

In total, 19 articles met the inclusion criteria and were included in this analysis. The overall quality of the studies included in this review was rated as moderate. Seven of the 19 studies reported no significant differences between the 2 groups in regards to baseline clinical and demographic characteristics (comorbidity index, American Society of Anesthesiologists grade, preoperative clinical subjective scores). Nearly all from these 7 studies with comparable initial characteristics documented no significant differences in the overall complication rates between the 2 groups in addition to no difference in mortality rate, cardiac complications, revision rate, thromboembolic events, and functional outcomes.

CONCLUSION

In contemporary studies involving comparable baseline demographics (including comorbidity index, American Society of Anesthesiologists grade), there was moderate evidence to show that simultaneous BTKA is as safe as the staged BTKA.

Postoperative Stiffness Requiring Manipulation Under Anesthesia Is Significantly Reduced After Simultaneous Versus Staged Bilateral Total Knee Arthroplasty

BACKGROUND

For patients with symptomatic bilateral knee arthritis, it is unknown whether the risk of developing stiffness requiring manipulation under anesthesia postoperatively is higher or lower for those undergoing simultaneous bilateral total knee arthroplasty (TKA) compared with those having staged bilateral TKA. Therefore, we undertook this study to evaluate the risk of requiring manipulation under anesthesia in staged versus simultaneous bilateral TKA as well as patients undergoing unilateral TKA.

METHODS

We utilized the California Patient Discharge Database, which is linked with the California Emergency Department, Ambulatory Surgery, and master death file databases. Using a literature-based estimate of the number of patients who failed to undergo the second stage of a staged bilateral TKA, replacement cases were randomly selected from patients who had unilateral TKA and were matched on 8 clinical characteristics of the patients who had staged bilateral TKA. Hierarchical multivariate logistic regression was performed to determine the risk-adjusted odds of manipulation in patients undergoing unilateral TKA, staged bilateral TKA, and simultaneous bilateral TKA using yearly hospital TKA volume as a random effect. Adjustment was made to allow fair comparison of the outcome at 90 and 180 days of follow-up after staged compared with simultaneous bilateral TKA.

RESULTS

During the time period from 2005 through 2013, the cumulative incidence of manipulation within 90 days was 2.14% for unilateral TKA (4,398 events per 205,744 patients), 2.11% for staged bilateral TKA (724 events per 34,352 patients), and 1.62% for simultaneous bilateral TKA (195 events per 12,013 patients). At 180 days of complete follow-up, the cumulative incidence of manipulation was 3.07% after unilateral TKA (6,313 events per 205,649 patients), 2.89% after staged bilateral TKAs (957 events per 33,169 patients), and 2.29% after simultaneous bilateral TKA (267 events per 11,653 patients). With multivariate analyses used to adjust for relevant risk factors, the 90-day odds ratio (OR) of undergoing manipulation after simultaneous bilateral TKA was significantly lower than that for unilateral TKA (OR = 0.70; 95% confidence interval [CI], 0.57 to 0.86) and staged bilateral TKA (OR = 0.71; 95% CI, 0.57 to 0.90). Similarly, at 180 days, the odds of undergoing manipulation were significantly lower after simultaneous bilateral TKA than after both unilateral TKA (OR = 0.71; 95% CI, 0.59 to 0.84) and staged bilateral TKA (OR = 0.76; 95% CI, 0.63 to 0.93). The frequency of manipulation was significantly associated with younger age, fewer comorbidities, black race, and the absence of obesity.

CONCLUSIONS

Although the ORs were small (close to 1), simultaneous bilateral TKA had a significantly decreased rate of stiffness requiring manipulation under anesthesia at 90 days and 180 days after knee replacement compared with that after staged bilateral TKA and unilateral TKA.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Improvement in health-related quality of life after unilateral total knee arthroplasty in patients with bilateral knee osteoarthritis

PURPOSE

To review the outcome of unilateral total knee arthroplasty (TKA) in patients with bilateral knee osteoarthritis (OA) to determine whether unilateral TKA can achieve good health-related quality of life (HRQoL).

METHODS

Records of 68 women and 25 men with severe bilateral knee OA who underwent unilateral TKA on the more symptomatic knee by a single surgeon and did not return for the second TKA within 2 years were reviewed. Outcome at 6 months and 2 years was assessed using the mental and physical component summary (MCS and PCS) of the Short-Form 36 (SF-36) for HRQoL as well as the Oxford Knee Score (OKS) and Knee Society Score (KSS) for knee-specific outcome.

RESULTS

The SF-36, OKS, and KSS improved significantly after unilateral TKA. Respectively for MCS and PCS of SF-36, OKS, and KSS knee and function scores, 65%, 89%, 98%, 98%, and 98% of patients reported absolute improvement at 2 years. Respectively for PCS, OKS, and KSS function score that a minimal clinically important difference (MCID) was established, 77%, 96%, and 80% of patients achieved MCID at 2 years.

CONCLUSION

Unilateral TKA achieves good outcome in HRQoL at 2 years in patients with bilateral knee OA.