Development and Validation of Crosswalks Between the Western Ontario & McMaster Universities Osteoarthritis Index and Hip Disability and Osteoarthritis Outcome Score Joint Replacement/Knee Injury and Osteoarthritis Outcome Score Joint Replacement

BackgroundThe wide variety of patient-reported outcome measures used to assess outcomes following total joint arthroplasty can present a substantial methodological obstacle when attempting to compare information across studies or between institutions. A simple solution is to create crosswalks that reliably convert scores between patient-reported outcome measures. Our goal is to create and validate crosswalks between the commonly used Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) and short-form versions of the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR)/Knee Injury and Osteoarthritis Outcome Score (KOOS JR.).MethodsPatients in our joint replacement registry were included if they underwent primary total hip arthroplasty (n = 4649) or total knee arthroplasty (n = 3750) for osteoarthritis between May 2007 and February 2012. We used their preoperative and 2-year postoperative HOOS scores (n = 6351) or KOOS scores (n = 4688) to generate the patients’ WOMAC and HOOS JR/KOOS JR scores. The equipercentile equating method was applied to create 10 crosswalks: HOOS JR/KOOS JR to WOMAC Total (WOMAC-T), and WOMAC-T, WOMAC Pain (WOMAC-P), WOMAC Stiffness (WOMAC-S), and WOMAC Function (WOMAC-F) to HOOS JR/KOOS JR. Crosswalk validity was assessed by comparing actual and derived scores using Spearman’s rank correlation coefficients in a bootstrapped cohort.ResultsAll 10 crosswalks showed strong positive correlations ranging from 0.846 (WOMAC-S to KOOS JR) to 0.981 (HOOS JR to WOMAC-T).ConclusionWe created and validated 10 crosswalks between WOMAC and HOOS JR/KOOS JR. We recommend using the crosswalks between WOMAC-T and HOOS JR/KOOS JR when possible, as they demonstrated the highest correlation. WOMAC-F or WOMAC-P should be used in favor of WOMAC-S if only subscores are available. The HOOS JR/KOOS JR should only be converted to a WOMAC-T.Level of EvidenceLevel III.     

Validation of the Spanish Version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) for Elderly Patients With Total Knee Replacement

The purpose of this study was to validate the Knee Injury and Osteoarthritis Outcome Score (KOOS) for elderly patients who undergo total knee replacement (TKR). The validated Spanish versions of the KOOS and Medical Outcomes Study 36‐Item Short‐Form Health Survey (SF‐36) questionnaires were applied to 137 patients (mean age 72.3, SD 7.5 years). Test–retest data were collected with an intermediate period of 1–2 weeks. To evaluate the clinimetric properties of the KOOS, internal consistency (Cronbach's α), reproducibility (intraclass correlation coefficient [ICC]), construct validity (Spearman's correlation), responsiveness (effect sizes [ES], and standardized response mean [SRM]), and floor and ceiling effects (<15%) were assessed. As result, Cronbach's coefficients of the KOOS subscales ranged from 0.78 to 0.93, and ICC from 0.76 to 0.91. Construct validity was supported by the confirmation of the three predefined hypotheses involving expected correlations between KOOS subscale and SF‐36 physical health subscales. Spearman's correlations were strong between KOOS Pain and SF‐36 Bodily Pain (r = 0.81), KOOS Pain and SF‐36 Physical Functioning (r = 0.67), KOOS activities of daily living (ADL) and SF‐36 Bodily Pain (r = 0.69), KOOS ADL and SF‐36 Physical Functioning (r = 0.74), and KOOS Sports/Recreation and SF‐36 Physical Functioning (r = 0.76). Responsiveness at 1 year after TKR was large with the ES ranging from 0.81 to 2.12, and the SRM from 0.70 to 1.91. Floor and ceiling effects were low. In conclusion, the Spanish version of KOOS has successful psychometric characteristics and is a reliable and valid instrument for assessment of patient‐relevant outcomes in elderly patients with advanced OA who undergo TKR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2157–2162, 2019     

Reliability and Validity of the Knee Injury and Osteoarthritis Outcome Score in Patients Undergoing Unicompartmental Knee Arthroplasty

BackgroundThe Knee Injury and Osteoarthritis Outcome Score (KOOS) was developed to document outcomes from knee injury, including the impact of osteoarthritis on knee function. The purpose of this study is to determine the reliability and validity of the KOOS subscales for evaluating outcomes following unicompartmental knee arthroplasty (UKA).MethodsKOOS Pain, Activities of Daily Living (ADL), Sport, Symptoms, and Quality of Life (QoL) scores collected from 172 patients who underwent UKA were used in the analysis. KOOS subscales were tested for reliability and validity of scores through a Rasch model analysis.ResultsKOOS Sport, KOOS ADL, and KOOS QoL had good evidence of reliability with acceptable person reliability, person separation, and item reliability. For overall scale functioning, KOOS Pain, Symptoms, and ADL all had 1 question that did not have an acceptable value for infit or outfit mean square value. Questions in KOOS Sport and QoL all had acceptable values. There was a positive, linear relationship between the Short-Form 12 Physical Component Summary and the KOOS subscales which indicated good evidence of convergent validity. These associations were also seen when the cohort was separated in medial and lateral UKA.ConclusionTwo of the 5 KOOS subscales (KOOS Sport and KOOS QoL) were considered adequate in measuring outcomes, as well as reliability. The KOOS ADL had borderline values; however, it had adequate infit and outfit values. The KOOS Pain and Symptom score performed poorly in this analysis. For documenting outcomes following UKA, this study supports the use of KOOS ADL, Sport, and QoL.     

African American Patients Have Improved Functional Gains and Comparable Clinical Outcomes to Caucasian Patients After Total Hip and Knee Arthroplasty

BackgroundWith the increasing popularity of alternative payment models, minorities who use more postacute care resources may face difficulties with access to quality total hip arthroplasty (THA) and total knee arthroplasty (TKA) care. The purpose of this study is to compare differences in perioperative complications and functional outcomes between African American and Caucasian patients undergoing THA and TKA.MethodsWe reviewed a consecutive series of all primary THA and TKA patients at our institution from 2015 to 2018. Demographics, comorbidities, 90-day complications, readmissions, Veterans Rand 12-Item Health Survey (VR-12), Hip disability Osteoarthritis Outcome Score (HOOS), and Knee injury and Osteoarthritis Outcome Scores (KOOS) were compared between African American and Caucasian patients. A multivariate analysis was performed to control for confounding variables.ResultsOf the 5284 patients included in the study, 1041 were African American (24.5%). Although African American patients had lower preoperative HOOS/KOOS (33.5 vs 45.1, P < .001) and mental VR-12 scores (37.8 vs 51.5, P < .001) compared with Caucasian patients, there was no clinical difference at 1 year in HOOS/KOOS (50.2 vs 50.4), mental VR-12 (55.0 vs 52.6), or physical VR-12 scores (39.5 vs 39.8). When controlling for demographics and medical comorbidities, African American race was associated with increased rehabilitation facility discharge (odds ratio, 1.69; P < .001) but no difference in readmissions or complications.ConclusionAlthough African American patients had lower preoperative functional scores, they made improved postoperative gains when compared with Caucasian patients. Although there was no difference in postoperative complications, further studies should assess social causes for the increase in rehabilitation utilization rates in minority patients.     

Identifying Aseptic Revision Total Knee Arthroplasty Diagnoses That Achieve Minimal Clinically Important Difference and Patient Acceptable Symptom State

BackgroundMinimal clinically important difference (MCID) defines a meaningful clinical change in patient-reported outcome measures. Patient acceptable symptom state (PASS) provides a patient-reported outcome measures threshold value to indicate a satisfactory clinical state. MCID and PASS for revision total knee arthroplasty (rTKA) are ill-defined. Moreover, it is unknown whether diagnosis influences the likelihood of achieving MCID or PASS. The purpose of this study was to calculate MCID for aseptic rTKA and compare the percentage of patients achieving MCID and PASS per diagnosis.MethodsAn institutional registry of rTKA was used. First-time aseptic rTKA were included. Demographics, revision diagnosis, preoperative Knee Injury and Osteoarthritis Outcome Score, Jr (KOOS Jr), and 1-year postoperative KOOS Jr were recorded. The 1-year postoperative KOOS Jr PASS score was available. MCID was calculated using distribution-based methods. Three hundred fifty eight first-time aseptic rTKAs were analyzed. The 3 most common diagnoses were aseptic loosening (n = 156), instability (n = 109), and stiffness (n = 37).ResultsThe mean KOOS Jr 1-year postoperative MCID for rTKA was 10.3. Overall, 75.4% achieved MCID and 56.9% achieved PASS. The percentage of patients per diagnosis achieving MCID and PASS, respectively, were periprosthetic fracture (100, 44), aseptic loosening (94, 60), implant fracture (88, 63), stiffness (60, 38), instability (59, 61), polyethylene wear/osteolysis (57, 57), and metal allergy (44, 33).ConclusionAseptic rTKA MCID is 10.3 for KOOS Jr at 1 year postoperatively. rTKA outcomes vary depending on preoperative diagnosis. Even in diagnoses with a high proportion of MCID achieved, less than 2/3 of patients achieved PASS, suggesting rTKA provides noticeable improvement but may not return patients to a satisfactory state.     

Accuracy and Validity of Computer Adaptive Testing for Outcome Assessment in Patients Undergoing Total Hip Arthroplasty

BackgroundProbability-based computer algorithms that reduce patient burden are currently in high demand. These computer adaptive testing (CAT) methods improve workflow and reduce patient frustration, while achieving high measurement precision. In this study, we evaluated the accuracy and validity of the CAT Hip Disability and Osteoarthritis Outcome Score (HOOS) and the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS-JR) by comparing them to the full version of these scoring systems in a subset of patients who had undergone total hip arthroplasties.MethodsA previously developed CAT HOOS and HOOS-JR was applied to 354 and 1547 HOOS and HOOS-JR patient responses, respectively. Mean, standard deviations, Pearson’s correlation coefficients, interclass correlation coefficients, frequency distribution plots, and Bland-Altman plots were used to compare the precision, validity, and accuracy between CAT scores and full-form scores.ResultsBy modifying the questions to past responses, the CAT HOOS demonstrated a mean reduction of 30% of questions (28 vs 40 questions). There were no significant differences between the full HOOS and CAT HOOS with respect to pain (P = .73), symptoms (P = .94), quality of life (P = .99), activities of daily living (P = .82), and sports (P = .99). There were strong linear relationships between the CAT versions and the standard questionnaires (r > 0.99). The Bland-Altman plot showed that differences between CAT HOOS and full HOOS were independent of the overall scores.ConclusionThe CAT HOOS and HOOS-JR have high correlation and require fewer questions to finish compared to the standard full-form questionnaires. This may represent a reliable and practical alternative that may be less burdensome to patients and may help improve compliance for reporting outcome metrics.     

The trajectory of recovery and the inter-relationships of symptoms, activity and participation in the first year following total hip and knee replacement

Objective

Primary total hip (THR) and knee (TKR) replacement outcomes typically include pain and function with a single time of follow-up post-surgery. This research evaluated the trajectory of recovery and inter-relationships within and across time of physical impairments (PI) (e.g., symptoms), activity limitations (AL), and social participation restrictions (PR) in the year following THR and TKR for osteoarthritis.

Design

Participants (hip: n = 437; knee: 494) completed measures pre-surgery and at 2 weeks, 1, 3, 6 and 12 months post-surgery. These included PI (Hip Disability and Osteoarthritis Outcome Score (HOOS)/Knee Injury and Osteoarthritis Outcome Score (KOOS) symptoms and Chronic Pain Grade); AL (HOOS/KOOS activities of daily living and sports/leisure activities); and, PR (Late Life Disability and the Calderdale community mobility). Repeated measures analysis of variance (RANOVA) was used to evaluate the trajectory of recovery of outcomes and the inter-relationships of PI, AL and PR were evaluated using path analysis. All analyses were adjusted for age, sex, obesity, THR/TKR, low back pain and mood.

Results

THR: age 31–86 years with 55% female; TKR: age 35–88 years with 65% female. Significant improvements in outcomes were observed over time. However, improvements were lagged over time with earlier improvements in PI and AL and later improvements in PR. Within and across time, PI was associated with AL and AL was associated with PR. The magnitude of these inter-relationships varied over time.

Conclusion

Given the lagged inter-relationship of PI, AL and PR, the provision and timing of interventions targeting all constructs are critical to maximizing outcome. Current care pathways focusing on short-term follow-up with limited attention to social and community participation should be re-evaluated.     

Comparison of Expectations and Outcomes in Rheumatoid Arthritis Versus Osteoarthritis Patients Undergoing Total Knee Arthroplasty

BackgroundWe hypothesized that patients undergoing primary total knee arthroplasty (TKA) for rheumatoid arthritis (RA) would have different preoperative expectations compared to osteoarthritis (OA) patients, and that postoperative satisfaction would correlate with specific postoperative pain and functional domains.MethodsThis is a retrospective cohort study of RA patients matched based on age, gender, American Society of Anesthesiologists score, and Charlson Comorbidity Index score 1:2 with OA patients (76 RA, 152 OA) who underwent primary TKA. The Hospital for Special Surgery Knee Replacement Expectations Survey, Visual Analogue Scale for Pain (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), and the Short Form-12 (SF-12) were compared at baseline and at 2 years postoperatively. Minimum clinically important differences (MCIDs) were calculated for KOOS and SF-12 subdomains.ResultsPreoperatively, RA patients had lower expectations, worse VAS Pain, and worse KOOS Pain, Symptoms, and Activities of Daily Living (P < .05). However, at 2 years, RA patients had significantly larger improvements in VAS (P = .01) and these 3 KOOS subdomains (P < .05), achieving comparable absolute scores to OA patients. Overall, 86.1% of RA and 87.1% of OA patients were either somewhat or very satisfied with their TKA. Patient satisfaction correlated with VAS Pain and KOOS outcome scores in both groups. RA and OA patients had high rates of achieving MCID in SF-12 physical component scores and all 5 KOOS subdomains. A higher proportion of RA patients achieved MCID in KOOS Symptoms (98.4% vs 77.2%, P < .001).ConclusionRA patients had lower baseline expectations compared to OA patients. However, RA patients had greater improvements in KOOS and SF-12 subdomains, and there was no difference in satisfaction compared to OA patients after TKA.     

Outcomes Vary Significantly Using a Tiered Approach to Define Success After Total Knee Arthroplasty

BackgroundPatient-reported outcome measures (PROM) allow assessment of clinical outcomes following primary total knee arthroplasty (TKA). The purpose of this study is to use progressively more stringent definitions of success to examine clinical outcomes of primary TKA at 1 year postoperatively and to determine which demographic variables were associated with achieving clinical success.MethodsThe American Joint Replacement Registry was queried from 2012 to 2020 for primary TKA. Patients who completed the following PROMs preoperatively and 1 year postoperatively were included: Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and KOOS for Joint Replacement (KOOS JR). Mean PROM scores were determined for each visit and between-visit changes were evaluated using paired t-tests. Rates of achievement of minimal clinically important difference (MCID) by distribution-based and anchor-based criteria, Patient Acceptable Symptom State, and substantial clinical benefit were calculated. Logistic regression was used to evaluate the association between demographic variables and odds of clinical success.ResultsIn total, 12,341 TKAs were included. Mean improvement in PROM scores were as follows: KOOS JR, 29; WOMAC-Pain, 33; and WOMAC-Function, 31 (P < .0001 for all). Rates of achievement of each metric were the following: distribution-based MCID, 84%-87%; anchor-based MCID, 46%-79%; Patient Acceptable Symptom State, 54%-82%; and substantial clinical benefit, 68%-81%. Patient age and gender were the most influential demographic factors on achievement of clinical success.ConclusionClinical outcomes at 1 year following TKA vary significantly when using a tiered approach to define success. A tiered approach to interpretation of PROMs should be considered for future research and clinical assessment.     

Mapping and Crosswalk of the Oxford Hip Score and Different Versions of the Hip Disability and Osteoarthritis Outcome Score

BackgroundPatient-reported outcome measures such as the Oxford-12 Hip Score and Hip Disability and Osteoarthritis Outcome Score (HOOS) are used in daily orthopaedic practice to evaluate patients. Because different studies use different scores, it would be important to build conversion tables between scores (crosswalk) to compare the results of one study with those of another study. Various mapping methods can be used to develop crosswalk tables that convert Oxford-12 scores to the HOOS (and its derivatives, including the HOOS physical function short form, HOOS joint replacement, and HOOS-12) and vice versa. Although prior studies have investigated this issue, they are limited to short forms of the HOOS score. Consequently, they cannot be applied to hip preservation surgery and do not include quality-of-life items, whereas the Oxford-12 Hip Score is used for all hip evaluations.Questions/purposesWe prospectively studied the Oxford-12 and HOOS and its derivatives to (1) determine which version of the HOOS has the best mapping with the Oxford-12, (2) define the most-appropriate mapping method using selected indicators, and (3) generate crosswalk tables between these two patient-reported outcome measures.MethodsThe study enrolled 500 adult patients before primary THA (59% men [294 of 500 patients]) with hip osteoarthritis or avascular necrosis of the femoral head who completed the HOOS and Oxford-12. Patients were recruited from January 2018 to September 2019 in a tertiary-care university hospital, and we included all primary THAs in patients older than 18 years with a BMI lower than 35 kg/m² and greater than 18 kg/m². After a minimum of 6 months of follow-up, 39% (195 of 500) of the patients were assessed using the same tools. To determine which version of the HOOS mapped best to the Oxford-12 and what the most-appropriate mapping method was, we used preoperative data from all 500 patients. Because there is no consensus on the method to establish crosswalk, various mapping methods (linear regression, tobit regression, and quantile regression) and equating methods (linear equating and equipercentile method) were applied along with cross-validation to determine which method was the most suitable and which form of the HOOS provided the best result according to different criteria (mean absolute error, r², and Kolmogorov-Smirnov distance).To generate crosswalk tables, we created a conversion table (between the Oxford-12 and the HOOS form that was chosen after answering our first research question and the method chosen after answering our second question) using preoperative and postoperative data (n = 695). This table was meant to be simple to use and allows easy conversions from one scoring system to another.ResultsThe Oxford-12 and HOOS were strongly correlated (Pearson correlation coefficient range 0.586-0.842) for the HOOS subcategories and HOOS physical function, HOOS joint replacement, and HOOS-12. The correlation between the HOOS-12 and Oxford-12 was the strongest (r = 0.825). According to the three different criteria and five methods, the HOOS-12 was the best suited for mapping. The goal was to minimize the mean absolute error (perfect model = 0), have a Kolmogorov-Smirnov distance as close as possible to 0, and have the r² as close as possible to 1. Regarding the most-suitable method for the crosswalk mapping (research question 2), the five methods generated similar results for the r² (range 0.63-0.67) and mean absolute error (range 6-6.2). For the Kolmogorov-Smirnov distance, the equipercentile method was the best (Kolmogorov-Smirnov distance 0.04), with distance reduced by 43% relative to the regression methods (Kolmogorov-Smirnov distance 0.07). A graphical comparison of the predicted and observed scores showed that the equipercentile method provided perfect superposition of predicted and observed values after mapping. Finally, crosswalk tables were produced between the HOOS-12 and Oxford-12.ConclusionThe HOOS-12 is the most complete and suitable form of the HOOS for mapping with the Oxford-12, while the equipercentile method is the most suitable for predicting values after mapping. This study provides clinicians with a reliable tool to crosswalk between these scores not only for joint arthroplasty but also for all types of hip surgeries while also assessing quality of life. Our findings should be confirmed in additional studies.Clinical RelevanceThe resulting crosswalk tables can be used in meta-analyses, systematic reviews, or clinical practice to compare clinical studies that did not include both outcome scores. In addition, with these tools, the clinician can collect only one score while still being able to compare his or her results with those obtained in other databases and registries, and to add his or her results to other databases and joint registries.     

Validation of the Dutch version of the Hip disability and Osteoarthritis Outcome Score

INTRODUCTION: The Hip disability and Osteoarthritis Outcome Score (HOOS) was constructed in Sweden; this questionnaire has proved to be valid for persons with hip disability with or without hip osteoarthritis (OA) and with high demands of physical function. OBJECTIVE: The objective of this study was to evaluate the internal consistency, reliability, construct validity, and floor and ceiling effects of the Dutch version of the HOOS questionnaire. PATIENTS AND METHODS: After translation with a forward/backward protocol, 74 hip arthroplasty patients and 88 hip OA patients filled in the Dutch HOOS, as well as a Short Form-36 (SF-36), an Oxford Hip Score (OHS) and a VAS-pain questionnaire. RESULTS: The Dutch version of the HOOS questionnaire achieved excellent scores in all of the clinimetric properties. CONCLUSION: The Dutch HOOS questionnaire has a good internal consistency and reliability. Moreover, the construct validity is good and no floor and ceiling effects were found. The HOOS is a good instrument for patients with different stadia of hip OA.     

High Pre-Operative Expectations Precede Both Unfulfilled Expectations and Clinical Improvement After Total Hip and Total Knee Replacement

BackgroundThis prospective study aimed to examine whether patients’ and physicians’ outcome expectations were related to subjective (ie, fulfillment of expectations) and objective outcomes (ie, change in pain and function) in hip and knee arthroplasty patients up to 6 months post-surgery.MethodsPatients’ (N = 395) and physicians’ outcome expectations were examined 1 week post-consultation. Patients’ post-operative functional status and the extent of fulfillment of expectations were examined 5 weeks, 3 months, and 6 months post-surgery. Patients and physicians completed the Hospital for Special Surgery Hip/Knee Replacement (Fulfillment) Expectations Survey. Patients completed the Hip/Knee injury and Osteoarthritis Outcome Score. Linear regression analyses were performed to examine the relationship between physicians’ expectations and patients’ change in pain and function and extent of fulfillment of expectations, and a possible mediated effect of patients’ pre-operative expectations.ResultsPatients’ high expectations were consistently associated with better objective outcomes (ie, change in pain and function). Yet, high expectations in patients were also negatively related to subjective outcomes (ie, the extent of fulfillment of expectations). Physicians’ expectations were only positively associated with objective improvement in knee patients, and not in hip patients. Additionally, knee patients’ expectations partly mediated the relationship between physicians’ expectations and change in pain and function, 6 months post-surgery.ConclusionAlthough patients’ high expectations were associated with better objective outcomes, improvement was still less than patients expected. Thus, patients often have too high expectations of outcomes of surgery. In addition, physicians were able to influence patients’ expectations and to change experienced knee patients’ outcomes.     

High-Flexion Total Knee Replacement: Functional Outcome at One Year

Implants designed for enhanced flexion offer the prospect of improved function after total knee replacement (TKR). Whereas most studies evaluating these implants have focused on the range of knee flexion achieved, this study investigated the quality of function in deep knee flexion. The influences of residual pain and maximum flexion angle on function in deep knee flexion were also examined. Eighty-three patients (100 knees) were prospectively followed for 1 year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis. Range of motion was measured and Knee Society scores were calculated. A questionnaire evaluated residual knee pain and function in high-flexion activities. Mean Knee Society score was 95, and mean knee flexion was 125°, yet 20% of patients could neither kneel, nor squat, nor sit on their heels. Fifty-seven percent were able to kneel without significant difficulty; 69% were able to squat without significant difficulty; and 46% were able to sit on their heels without significant difficulty. Function in deep flexion correlated with pain scores but did not correlate with knee flexion angles or Knee Society scores. Results 1 year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis are encouraging, but one in five patients remain significantly limited in high-flexion activities.     

Assessment of a Satisfaction Measure for Use After Primary Total Joint Arthroplasty

BackgroundPatient satisfaction after total hip (THA) and total knee arthroplasty (TKA) is a core outcome selected by the Outcomes Measurement in Rheumatology. Up to 20% of THA/TKA patients are dissatisfied. Improving patient satisfaction is hindered by the lack of a validated measurement tool that can accurately measure change.MethodsThe psychometric properties of a proposed satisfaction instrument, consisting of 4 questions rated on a Likert scale, scored 1-100, were tested for validity, reliability, and sensitivity to change using data collected between 2007 and 2011 in an arthroplasty registry.ResultsWe demonstrated construct validity by confirming our hypothesis; satisfaction correlated with similar constructs. Satisfaction correlated moderately with pain relief (TKA ρ = 0.61, THA ρ = 0.47) and function (TKA ρ = 0.65, THA ρ = 0.51) at 2 years; there was no correlation with baseline/preoperative pain/function values, as expected. Overall Cronbach’s alpha >0.88 confirmed internal consistency. Test-retest reliability with weighted kappa ranged 0.60-0.75 for TKA and 0.36-0.56 for THA. Hip disability and Osteoarthritis Outcome Score/Knee injury and Osteoarthritis Outcome Scores quality of life improvement (>30 points) corresponds to a mean satisfaction score of 93.2 (standard deviation, 11.5) after THA and 90.4 (standard deviation, 13.8) after TKA, and increasing relief of pain and functional improvement increased the strength of their association with satisfaction. The satisfaction measure has no copyright and is available free of cost and represents minimal responder burden.ConclusionPatient satisfaction with THA/TKA can be measured with a validated 4-item questionnaire. This satisfaction measure can be included in a total joint arthroplasty core measurement set for total joint arthroplasty trials.     

Hip resurfacing: expectations and limitations

Background and purpose Long-term follow-up studies after total knee replacement (TKR) using an LCS rotating platform have shown survival rates of up to 97%. Few studies have evaluated short-term functional outcome and its improvement over time. We determined the time course of functional outcome as evaluated by the knee injury and osteoarthritis outcome score (KOOS) over the first 4 years after TKR using the LCS mobile bearing.

Patients and methods 50 unselected patients (mean age 70 (40–85) years, 33 women) with osteoarthritis in one knee underwent TKR with an LCS mobile bearing. Data were collected by an independent investigator preoperatively and at 6 weeks, 3 months, 6 months, 1 year, 2 years and 4 years postoperatively. KOOS, a self-assessment function score validated for this purpose, and range of motion (ROM) were determined at all follow-ups.

Results The mean KOOS pain score increased from 43 before surgery to 66 at 6 weeks and 88 at 2 years. It was 84 at 4 years. The mean KOOS activities of daily living score (ADL) increased from 49 before surgery to 73 at 6 weeks, then gradually to 90 at 2 years. It decreased to 79 at 4 years. Mean passive ROM was 112° before surgery, 78° at departure from hospital, and then gradually increased to 116° at 2 years and 113° at 4 years.

Interpretation Recovery after TKR is time-dependent. Most of the expected improvement in pain and function is achieved at 6 months postoperatively, but some further improvement can be expected up to 2 years postoperatively. ROM will also gradually improve up to 2 years after TKR, and reach the same level as before surgery.     

The Effects of Bundled Payment Programs for Hip and Knee Arthroplasty on Patient-Reported Outcomes

BackgroundPatient-reported outcomes are essential to demonstrate the value of hip and knee arthroplasty, a common target for payment reforms. We compare patient-reported global and condition-specific outcomes after hip and knee arthroplasty based on hospital participation in Medicare’s bundled payment programs.MethodsWe performed a prospective observational study using the Comparative Effectiveness of Pulmonary Embolism Prevention after Hip and Knee Replacement trial. Differences in patient-reported outcomes through 6 months were compared between bundle and nonbundle hospitals using mixed-effects regression, controlling for baseline patient characteristics. Outcomes were the brief Knee Injury and Osteoarthritis Outcomes Score or the brief Hip Disability and Osteoarthritis Outcomes Score, the Patient-Reported Outcomes Measurement Information System Physical Health Score, and the Numeric Pain Rating Scale, measures of joint function, overall health, and pain, respectively.ResultsRelative to nonbundled hospitals, arthroplasty patients at bundled hospitals had slightly lower improvement in Knee Injury and Osteoarthritis Outcomes Score (−1.8 point relative difference at 6 months; 95% confidence interval −3.2 to −0.4; P = .011) and Hip Disability and Osteoarthritis Outcomes Score (−2.3 point relative difference at 6 months; 95% confidence interval −4.0 to −0.5; P = .010). However, these effects were small, and the proportions of patients who achieved a minimum clinically important difference were similar. Preoperative to postoperative change in the Patient-Reported Outcomes Measurement Information System Physical Health Score and Numeric Pain Rating Scale demonstrated a similar pattern of slightly worse outcomes at bundled hospitals with similar rates of achieving a minimum clinically important difference.ConclusionsPatients receiving care at hospitals participating in Medicare’s bundled payment programs do not have meaningfully worse improvements in patient-reported measures of function, health, or pain after hip or knee arthroplasty.     

A Randomized Controlled Trial Comparing a Medial Stabilized Total Knee Prosthesis to a Cruciate Retaining and Posterior Stabilized Design: A Report of the Clinical and Functional Outcomes Following Total Knee Replacement

BackgroundThe purpose of this randomized controlled trial was to compare the performance of 3 total knee joint replacement (TKJR) designs 6 months after the surgery.MethodsPatients were recruited between March 2015 and March 2018. Patients with osteoarthritis consented for TKJR were randomly allocated to a medial stabilized (MS), cruciate retaining (CR), or posterior stabilized (PS) design. Primary outcome measures were self-reported improvement in pain and function 6 months after TKJR, using the Oxford Knee Score. Secondary outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index, Veterans RAND 12-item Health Survey, Knee Society Score 2011, Timed Up and Go test, and Six-Minute Walk Test. Twelve-month outcomes were also measured.ResultsNinety participants enrolled, 83 were randomized: PS (n = 26), CR (n = 28), and MS (n = 29) designs. One case withdrew before surgery: planned use of non-study implant; 7 did not complete all outcome measures. No 6-month between-group difference was observed for the primary outcome. A 6-month difference was observed in Knee Society Score 2011 Satisfaction: MS favored over CR and PS. Clinically meaningful 12-month differences in Western Ontario and McMaster Universities Osteoarthritis Index Pain, Function, and Global Subscales were observed: MS favored over CR. Twelve-month differences occurred in Veterans RAND 12-item Health Survey mental well-being, favoring MS and PS over CR.ConclusionMS prosthesis can be expected to yield similar clinical and functional outcomes to PS and CR designs 6 months after TKJR, and patients were more satisfied with their outcome. Compared with CR, patients with MS prosthesis also reported superior pain, function, and quality-of-life outcomes at 12 months.     

Postoperative Anteroposterior Laxity Influences Subjective Outcome After Total Knee Arthroplasty

Background

We hypothesized that postoperative anteroposterior (AP) stability of the knee correlates with patient-reported clinical outcome and knee function after total knee arthroplasty (TKA).

Patient Acceptable Symptom State for the Forgotten Joint Score in Primary Total Knee Arthroplasty

BackgroundIn order to better understand the clinical benefits of total knee arthroplasty (TKA) and improve the interpretability of the Forgotten Joint Score (FJS-12), the establishment of a meaningful change in score is necessary. The purpose of this study is to determine the threshold of the FJS-12 for detecting the patient acceptable symptom state (PASS) following primary TKA.MethodsWe retrospectively reviewed all patients who underwent elective, primary TKA and answered both the FJS-12 and the Knee Injury Osteoarthritis Outcome Survey, Joint Replacement KOOS, JR surveys 1-year postoperatively. The questionnaires were administered via a web-based electronic application. KOOS, JR score was used as the anchor. The anchor for PASS calculation should relate pain, physical function, and patient satisfaction. Two statistical methods were employed: (1) the receiver operating characteristic (ROC) curve point; (2) 75^th percentile of the cumulative percentage curve of patients who had the KOOS, JR score difference larger than the cut-off value.ResultsThis study included 457 patients. The mean 1-year FJS-12 score was 42.6 ± 27.8. The mean 1-year KOOS, JR score was 68.0 ± 17.2. A high positive correlation between FJS-12 and KOOS, JR was found (r = 0.72, P < .001) making the KOOS, JR a valid external anchor. The threshold score of the FJS-12 which maximized the sensitivity and specificity for detecting a PASS was 33.3 (AUC = 0.78, 95% CI [0.74, 0.83]). The cut-off value computed with the 75^th percentile approach was 77.1 (95% CI [73.9, 81.5]).ConclusionThe PASS threshold for the FJS-12 was 33.3 and 77.1 at 1-year follow-up after primary TKA using the receiver operating characteristic (ROC) curve and 75^th percentile approaches, respectively. These values can be used to assess the successful achievement of a forgotten joint.Level III EvidenceRetrospective Cohort Study.     

Comparison of KOOS Scores of Middle-Aged Patients Undergoing Total Knee Arthroplasty to the General Dutch Population Using KOOS Percentile Curves: The LOAS Study

BackgroundWe aimed to investigate the application of the Knee Injury and Osteoarthritis Outcome Score (KOOS) percentile curves, using preoperative and postoperative data of patients with knee osteoarthritis undergoing total knee arthroplasty (TKA).MethodsWe used Longitudinal Leiden Orthopedics Outcomes of Osteo-Arthritis study data of patients between 45 and 65 years and undergoing primary TKA. KOOS scores (0-100) were obtained preoperatively and 6, 12, and 24 months after TKA. Preoperative knee radiographs were assessed according to Kellgren-Lawrence (KL) in a subset (37%) of patients. Comorbidities were self-reported using a standardized questionnaire. The median (interquartile range) population-level KOOS scores were plotted on previously developed population-based KOOS percentile curves. In addition, we assessed the application of the curves on patient level and investigated differences in scores between patients with preoperative KL scores ≤2 and ≥3 and presence (vs absence) of comorbidities.ResultsThe study population consisted of 853 patients (62% women, mean age 59 years, body mass index 30 kg/m²) with knee osteoarthritis undergoing primary TKA. Preoperatively, median KOOS scores of all subscales were at or below the 2.5^th percentile. Scores increased to approximately the 25^th percentile 12 months postoperatively. Greater improvements were observed in pain and less improvements in sport and recreational function and quality of life. Patients with higher preoperative KL scores and without comorbidities showed greater improvements.ConclusionThe KOOS percentile curves provided visual insights in knee complaints of patients relative to the general population. Furthermore, the KOOS percentile curves give insight in how preoperative patient characteristics are correlated with postoperative results.