Inadequate Classification of Poor Response After Total Knee Arthroplasty: A Comparative Analysis of 15 Definitions Using Data from the Dutch Arthroplasty Register and the Osteoarthritis Initiative Database.

BACKGROUND: Variations in defining poor response to total knee arthroplasty (TKA) impede comparisons of response after TKA over time and across hospitals. This study aimed to compare the prevalence, overlap, and discriminative accuracy of 15 definitions of poor response after TKA using two databases. METHODS: Data of patients one year after primary TKA from the Dutch Arthroplasty Register (LROI) (n = 12,275) and the Osteoarthritis Initiative (OAI) database (n = 204) were used to examine the prevalence, overlap (estimated by Cohen's kappa), and discriminative accuracy (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Youden index) of 15 different definitions of poor response after TKA. In the absence of a gold standard for measuring poor response to TKA, the numeric rating scale (NRS) satisfaction (≤ 6 'poor responder') and the global assessment of knee impact (dichotomized: ≥ 4 'poor responder') were used as anchors for assessing discriminative accuracy for the LROI and OAI dataset, respectively. These anchors were chosen based on a prior qualitative study that identified (dis)satisfaction as a central theme of poor responses to TKA by patients and knee specialists. RESULTS: The median (25th to 75th percentile) prevalence of poor responders in the examined definitions was 18.5% (14.0 to 25.5%), and the median Cohen's kappa for the overlap between pairs of definitions was 0.41 (0.32 to 0.59). Median (25th to 75th percentile) sensitivity was 0.45 (0.39 to 0.54), specificity was 0.86 (0.82 to 0.94), PPV was 0.45 (0.34 to 0.62), NPV was 0.89 (0.87 to 0.89), and the Youden index was 0.36 (0.20 to 0.43). CONCLUSION: This found a lack of overlap between different definitions of poor response to TKA. None of the examined definitions adequately classified poor responders to TKA. In contrast, the absence of a poor response could be classified with confidence.

Prioritization of Adverse Consequences After Total Knee Arthroplasty Contributing to a Poor Response: A Best-Worst Scaling Exercise Among Total Knee Arthroplasty Patients and Knee Specialists.

BACKGROUND: Total knee arthroplasty (TKA) can have a number of adverse consequences for patients that might contribute to a poor outcome. This study aimed to prioritize these consequences, from the perspective of patients and knee specialists. METHODS: There were 95 TKA patients and 63 knee specialists who prioritized a set of 29 adverse consequences, based on a previous qualitative study, using a Maximum Difference Scaling method. A hierarchical Bayesian analysis was used to calculate relative importance scores. Differences and agreements between patients versus knee specialists and satisfied versus dissatisfied patients were analyzed using Mann-Whitney-U tests and Kendall's coefficients of concordance. RESULTS: There were 4 out of 5 items in the top-5 of both patients and knee specialists that were similar, however, the ranking was different. The highest-ranked consequence for patients was: "Inability to do normal activities such as walking, cycling, swimming and heavy household chores", while knee specialists ranked: "No improvement in pain during the day" as the highest. "No improvement in walking" was in the patients' top-5, but was not ranked in the top-5 of knee specialists. For satisfied and dissatisfied patients, the top-5 of consequences was similar. CONCLUSION: Comparable perspectives were found for patients versus knee specialists and satisfied versus dissatisfied patients on the importance of adverse consequences after TKA. However, when looking in more detail, differences in ranking of specific subitems suggest that patients place slightly more importance on the inability to perform valued activities, while knee specialists prioritize lack of pain relief to a higher degree.

Exploration of adverse consequences of total knee arthroplasty by patients and knee specialists: a qualitative study.

Objectives: A successful outcome according to the knee specialist is not a guarantee for treatment success as perceived by patients. In this study, we aimed to explore outcome expectations and experiences of patients with OA before and after total knee arthroplasty (TKA) surgery and knee specialists that might contribute to the negative appraisal of its effect, and differences in views between patients and knee specialists. Methods: Semi-structured interviews were held in Belgium and the Netherlands. Twenty-five patients (2 without indications for TKA, 11 on the waiting list for TKA and 12 postoperative TKA) and 15 knee specialists (9 orthopaedic surgeons, 1 physician assistant, 1 nurse practitioner and 4 physiotherapists) were interviewed. Conversations were audio recorded, transcribed verbatim, and analysed using thematic analysis following the grounded theory approach. Separate analyses were conducted for patients and knee specialists. Results: Patients were focused on the arduous process of getting used to the prosthesis, lingering pain, awareness of the artificial knee and limitations they experience during valued and daily activities, whereas knee specialists put emphasis on surgical failure, unexplained pain, limited walking ability and impairments that limit the physical functioning of patients. Conclusion: This study provides a comprehensive overview of potential adverse consequences from the perspective of both patients and knee specialists. Improving patients' awareness and expectations of adaptation to the knee prosthesis needs to be considered.

Acceptable migration of a fully cemented rotating hinge-type knee revision system measured in 20 patients with model-based RSA with a 2-year follow-up.

BACKGROUND AND PURPOSE: Rotating hinged knee implants are highly constrained prostheses used in cases in which adequate stability is mandatory. Due to their constraint nature, multidirectional stresses are directed through the bone-cement-implant interface, which might affect fixation and survival. The goal of this study was to assess micromotion of a fully cemented rotating hinged implant using radiostereometric analysis (RSA). PATIENTS AND METHODS: 20 patients requiring a fully cemented rotating hinge-type implant were included. RSA images were taken at baseline, 6 weeks, and 3, 6, 12, and 24 months postoperatively. Micromotion of femoral and tibial components referenced to markers in the bone was assessed with model-based RSA software, using implant CAD models. Total translation (TT), total rotation (TR), and maximal total point motion (MTPM) were calculated (median and range). RESULTS: At 2 years, TTfemur was 0.38 mm (0.15-1.5), TRfemur was 0.71° (0.37-2.2), TTtibia was 0.40 mm (0.08-0.66), TRtibia was 0.53° (0.30-2.4), MTPMfemur was 0.87 mm (0.54-2.8), and MTPMtibia was 0.66 mm (0.29-1.6). Femoral components showed more outliers (> 1 mm, > 1°) compared with tibial components. CONCLUSION: Fixation of this fully cemented rotating hinge-type revision implant seems adequate in the first 2 years after surgery. Femoral components showed more outliers, in contrast to previous RSA studies on condylar revision total knee implants.

Translation, cross-cultural adaptation, reliability and construct validity of the Dutch Oxford Knee Score - Activity and Participation Questionnaire.

BACKGROUND: Patients undergoing total knee arthroplasty (TKA) tend to be younger and tend to receive TKA at an earlier stage compared to 20 years ago. The Oxford Knee Score - Activity and Participation (OKS-APQ) questionnaire evaluates higher levels of activity and participation, reflecting activity patterns of younger or more active people. The purpose of this study was to translate the OKS-APQ questionnaire into Dutch, and to evaluate its measurement properties in pre- and postoperative TKA patients. METHODS: The OKS-APQ was translated and adapted according to the forward-backward translation multi step approach and tested for clinimetric quality. Floor and ceiling effects, structural validity, construct validity, internal consistency and test-retest reliability were evaluated using COSMIN quality criteria. The OKS-APQ, the Oxford Knee Score (OKS), the Short Form-36 (SF-36), a Visual Analogue Scale (VAS) for pain and the Forgotten Joint Score (FJS) were assessed in 131 patients (72 preoperative and 59 postoperative TKA patients), and the OKS-APQ was administered twice in 50 patients (12 preoperative and 38 postoperative TKA patients), after an interval of minimal 2 weeks. RESULTS: Floor effects were observed in preoperative patients. Confirmatory factor analyses (CFA) indicated a good fit of a 1-factor model by the following indices: (Comparative Fit Index (CFI): 0.97, Tucker-Lewis Index (TLI): 0.96 and Standardized Root Mean Square Residual (SRMR): 0.03). Construct validity was supported as > 75% of the hypotheses were confirmed. Internal consistency (Cronbach α's from 0.81 to 0.95) was good in the pooled and separate pre- and postoperative samples and test-retest reliability (Intraclass Correlation Coefficients (ICCs) from 0.63 - 0.85) were good in postoperative patients and moderate in preoperative patients. The standard Error of Measurements (SEMs) ranged from 8.5 - 12.2 and the Smallest Detectable Changes in individuals (SDCind) ranged from 23.5 - 34.0 (on a scale from 0 to 100). CONCLUSIONS: Preliminary findings suggest that the Dutch version of the OKS-APQ is reliable and valid for a Dutch postoperative TKA patient sample. However, in a preoperative TKA sample, the OKS-APQ seems less suitable, because of floor effects and lower test-retest reliability. The Dutch version of the OKS-APQ can be used alongside the OKS to discriminate among levels of activity and participation in postoperative patients.

Definitions of poor outcome after total knee arthroplasty: an inventory review.

BACKGROUND: A significant proportion of patients experiences poor response (i.e. no or little improvement) after total knee arthroplasty (TKA) because of osteoarthritis. It is difficult to quantify the proportion of patients who experiences poor response to TKA, as different definitions of, and perspectives (clinician's and patient's) on poor response are being used. The aim of this study was therefore to review the literature and summarize definitions of poor response to TKA. METHODS: A systematic search was performed to identify and review studies that included dichotomous definitions of poor outcome after primary TKA. The type, amount and combination of domains (e.g. functioning), outcome measures, type of thresholds (absolute/relative, change/cut-off), values and moments of follow-up used in definitions were summarized. RESULTS: A total of 47 different dichotomous definitions of poor response to TKA were extracted from 2163 initially identified studies. Thirty-six definitions incorporated one domain, seven definitions comprised two domains and four definitions comprised three domains. Eight different domains were used in identified definitions: pain, function, physical functioning, quality of life (QoL), patient satisfaction, anxiety, depression and patient global assessment. The absolute cut-off value was the most common type of threshold, with large variety in value and timing of follow-up. CONCLUSIONS: Our inventory review shows that definitions of poor response to TKA are heterogeneous. Our findings stresses the need for an unambiguous definition of poor response to draw conclusions about the prevalence of poor-responders to TKA across hospitals and countries, and to identify patients at risk.

Mid-flexion laxity in the asymptomatic native knee is predominantly present on the lateral side.

PURPOSE: During total knee arthroplasty (TKA), an orthopaedic surgeon is focused on soft-tissue balance in extension (0°) and in flexion (90°). Patients with instability problems of the knee often report a feeling of instability during daily life activities, at around 30° knee flexion. There are no reference values available for knee laxity of healthy subjects in mid-flexion (30°) and flexion (90°) for comparison with the TKA population. Therefore, the aim was to quantify varus and valgus knee laxity in extension, mid-flexion and flexion in the asymptomatic native knee. METHODS: In 40 healthy volunteers matched for age, gender and BMI with the TKA-population, varus and valgus knee laxity in extension (0°), mid-flexion (30°) and flexion (90°) was measured on low-dose radiographs. For each subject, one randomly selected knee was stressed in extension, mid-flexion and flexion (with 15 Nm) using a stress device. RESULTS: Varus laxity in mid-flexion was higher than in extension and flexion (p < 0.01). Valgus laxity tended to be highest in mid-flexion laxity; however, no differences in knee laxity between flexion angles were seen (n.s.). Varus knee laxity in extension was higher in females than in males (p < 0.05). CONCLUSIONS: Mid-flexion laxity in the native knee is more prominent on the lateral side of the knee, while the medial side is more stable and constrained. Varus knee laxity in extension was shown to be higher in females than in males. LEVEL OF EVIDENCE: Prognostic Level II.

Associations of adipose and muscle tissue parameters at colorectal cancer diagnosis with long-term health-related quality of life.

PURPOSE: Increased visceral adiposity (visceral obesity) and muscle wasting (sarcopenia) at colorectal cancer (CRC) diagnosis, quantified by computed tomography (CT) image analysis, have been unfavorably associated with short-term clinical outcomes and survival, but associations with long-term health-related quality of life (HRQoL) have not been investigated. We studied associations of visceral adiposity, muscle fat infiltration, muscle mass, and sarcopenia at CRC diagnosis with HRQoL 2-10 years post-diagnosis. METHODS: A cross-sectional study was conducted in 104 stage I‒III CRC survivors, diagnosed at Maastricht University Medical Center+, the Netherlands (2002-2010). Diagnostic CT images at the level of the third lumbar vertebra were analyzed to retrospectively determine visceral adipose tissue area (cm2); intermuscular adipose tissue area (cm2) and mean muscle attenuation (Hounsfield units) as measures of muscle fat infiltration; and skeletal muscle index (SMI, cm2/m2) as measure of muscle mass and for determining sarcopenia. RESULTS: Participants showed a large variation in body composition parameters at CRC diagnosis with a mean visceral adipose tissue area of 136.1 cm2 (standard deviation: 93.4) and SMI of 47.8 cm2/m2 (7.2); 47% was classified as being viscerally obese, and 32% as sarcopenic. In multivariable linear regression models, associations of the body composition parameters with long-term global quality of life, physical, role and social functioning, disability, fatigue, and distress were not significant, and observed mean differences were below predefined minimal important differences. CONCLUSIONS: Although visceral obesity and sarcopenia are relatively common at CRC diagnosis, we found no significant associations of these parameters with long-term HRQoL in stage I-III CRC survivors.