Do Knee Osteoarthritis Patterns Affect Patient-Reported Outcomes in Total Knee Arthroplasty? Results From an International Multicenter Prospective Study With 3-Year Follow-Up.

BACKGROUND: The aim of this multicenter study is to answer (1) Does patellofemoral osteoarthritis (OA) affect preoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) scores in total knee arthroplasty (TKA)? and (2) Do different OA patterns affect preoperative and postoperative KOOS scores in TKA? METHODS: This international, multicenter prospective study examined 384 TKA patients. Compartmental OA was divided into (1) medial, (2) medial + patellofemoral, (3) lateral, (4) lateral + patellofemoral, (5) medial + lateral (bicompartmental), and (6) medial + lateral + patellofemoral (tricompartmental), based on preoperative anterior-posterior and lateral ± skyline radiographs with Kellgren-Lawrence grade III-IV and joint space width <2.5 mm. KOOS was collected preoperatively, 1 year postoperatively, and 3 years postoperatively. Higher KOOS score represented better clinical state, for example, higher KOOS Pain score indicated less pain. RESULTS: Patellofemoral OA had no effect on preoperative KOOS scores (P > .15). Compared to medial ± patellofemoral OA patients, bicompartmental/tricompartmental OA patients had less preoperative pain (KOOS Pain 7.4, P = .03) and higher daily function (KOOS-ADL [Activities of Daily Living] 7.1, P = .05), and higher 1-year postoperative daily function (KOOS-ADL 9.2, P = .03) and sports activity (KOOS Sports & Recreation Function 15.0, P = .04), while lateral ± patellofemoral OA patients had more symptoms (KOOS-Symptoms 7.0, P < .01), more pain (KOOS-Pain 7.5, P = .01), lower daily function (KOOS-ADL 9.3, P < .01), and lower quality of life (KOOS-QOL 9.0, P = .04), at 3 years postoperatively. CONCLUSION: Patellofemoral OA does not affect medial ± lateral OA patients' preoperative KOOS scores, challenging the importance of patellofemoral OA in TKA. Lateral ± patellofemoral OA patients have lower postoperative KOOS scores than medial/more progressed compartmental OA patients, indicating that patients with less common OA patterns present with unique surgical challenges. Further development of indications for and correct timing of TKA surgery in different patient subgroups is needed.

External Validation of Achieving the Patient Acceptable Symptom State for the EuroQol-5 Dimension 1 Year After Total Hip Arthroplasty.

BACKGROUND: Patient acceptable symptom state (PASS) thresholds for the EuroQol-5 Dimension-3 Level (EQ-5D-3L) questionnaire have been established for patients being evaluated 1 year following total hip arthroplasty (THA) but with varying derivation cohorts and methods. The aim of this study was to (1) generate an EQ-5D PASS threshold 1 year following THA on the basis of an international patient cohort, (2) validate preexisting and newly generated PASS thresholds 1 year following THA using the institutional registry of an academic care center, and (3) assess whether THA PASS thresholds vary by patient age and sex. METHODS: The derivation cohort for the THA PASS threshold consisted of 774 patients (after exclusions) who were enrolled in an international, multicenter study from 2007 to 2012 and who completed the EQ-5D and a numerical rating scale (NRS) for satisfaction 1 year postoperatively. With the NRS dichotomized at 2.5 as the anchor, a PASS cutoff for the EQ-5D was generated using the 80% specificity method. The Youden method and 75th percentile approach served as sensitivity analyses. The external validation cohort comprised 1,472 patients who had undergone THA. PASS thresholds were used to dichotomize the external validation sample. The ability of the threshold to predict satisfaction was evaluated with receiver operating characteristic (ROC) curve analysis. Patient subcohorts were stratified by age (>65 and ≤65 years) and sex. RESULTS: Three THA PASS thresholds of 0.77 (our newly defined threshold), 0.82, and 0.92 were validated in this study. The EQ-5D PASS threshold of 0.77 (area under the curve [AUC] = 0.816) best predicted satisfaction 1 year after THA. Subcohort analyses yielded comparable 1-year PASS thresholds for THA between age cohorts and between sex cohorts. CONCLUSIONS: This study identifies PASS thresholds that best predict patient satisfaction 1 year following THA. Although the varied methodology and patient cohorts used to derive PASS values complicate the comparison of these thresholds, this analysis can help surgeons understand the level of health-related quality of life associated with patient satisfaction following THA. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Class III Obesity Increases Risk of Failure to Achieve the 1-Year Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form Minimal Clinically Important Difference Following Total Hip Arthroplasty.

BACKGROUND: The relationship between obesity and failure to achieve a minimal clinically important difference (MCID) following total hip arthroplasty (THA) has not been well defined. The aims of this study are to determine whether increasing body mass index (BMI) is associated with failure to achieve the 1-year Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form (HOOS-PS) MCID and to determine a threshold BMI beyond which this risk is significantly increased. METHODS: A multi-institutional arthroplasty registry was queried for THA patients from 2016 to 2018 with completion of preoperative and 1-year postoperative HOOS-PS. A previously defined anchor-based MCID threshold of 23 was used. Variables collected included demographics and patient-reported outcome measures. BMI was analyzed continuously and categorically. The association was analyzed via logistic regression. A BMI threshold was determined using the Youden index and receiver operating characteristic curve. RESULTS: A total of 1256 THAs were included. The average HOOS-PS improvement was 27.6 ± 18 points. The area under the receiver operating characteristic curve for BMI and risk of failure to achieve HOOS-PS MCID was 0.54 (95% confidence interval [CI], 0.50-0.57). Increasing BMI assessed continuously was a significant risk factor (odds ratio [OR], 1.03; 95% CI, 1.01-1.05; P value = .010). When BMI was analyzed categorically, this association was only observed for obese class III patients (>40 kg/m2) (OR, 2.5; 95% CI, 1.21-5.3; P value = .010). CONCLUSION: This study found an association between increasing BMI and failure to achieve the 1-year HOOS-PS MCID. Obese class III patients (>40 kg/m2) face a near 3-fold increased risk of suffering this adverse outcome.

Regional differences between the US, Scandinavia, and South Korea in patient demographics and patient-reported outcomes for primary total knee arthroplasty.

INTRODUCTION: Differences in total knee arthroplasty (TKA) patient demographics and clinical outcomes may exist between international regions, yet research is limited. The aim of this study was, therefore, to compare TKA patient demographics and patient-reported outcome measure (PROM) scores between the US, Scandinavia, and South Korea. MATERIALS AND METHODS: A total of 398 TKA patients from three regions were assessed: 169 in Scandinavia (3 centers), 129 in the US (3 centers), and 100 patients in South Korea (2 centers). Regional variation in patient demographics was assessed using Kruskal-Wallis H tests. Regional variation in PROM scores from preoperative, 1-, 3- and 5-year visits was assessed using piecewise linear mixed effect models. The PROMs analyzed were a numerical rating scale for satisfaction and the Knee Osteoarthritis Outcome Score. RESULTS: South Korean patients were the oldest (p < 0.001) and had the highest Charnley class (p < 0.001); US patients had the highest BMI (p < 0.001); Scandinavian patients had the lowest preoperative KL grade (p < 0.001). Scandinavian patients were associated with better preoperative and worse postoperative PROM scores. Scandinavian patients were also associated with moderately lower levels of satisfaction. These differences were lessened but remained significant after controlling for relevant demographic and surgical factors. CONCLUSIONS: Regional differences were found in TKA patient demographics and PROMs between the US, Scandinavia, and South Korea. The regional differences in patient demographics support the need for more research and clear guidelines related to TKA appropriateness criteria. The better preoperative and worse postoperative Scandinavian PROM scores may have been related to their less severe KL grade but might also reflect cultural differences in how patients reflect on their health state when answering PROMs. Clinicians should be aware of these international differences in PROM scores when interpreting studies conducted in different international regions. Future studies should investigate TKA variation between more international regions and assess intraregional variation. LEVEL OF EVIDENCE: Level III.