Page 153 - The value of total hip and knee arthroplasties for patients

Return to work after total hip and knee arthroplasty: results from a clinical study
(b) The Oxford Hip Score (OHS) and the Oxford Knee Score (OKS), which are short, twelve-item questionnaires developed for completion by patients undergoing THA and TKA.23, 24 We used validated Dutch translations for the present study.25, 26
Preoperative radiological severity
Preoperative supine radiographs of hips (anterior–posterior) and weight-bearing radiographs of the knees (posterior–anterior) were collected from the patients’ medical records. These radiographs were routinely made in the participating centers for preoperative templating purposes. All radiographs were assessed by an experienced musculoskeletal radiologist (HMK), who was blinded for the operated side and patient characteristics.The Kellgren and Lawrence (KL) grading system was used to classify the severity of OA (grade 0: no OA; grade 1: doubtful OA; grade 2: minimal OA; grade 3: moderate OA and grade 4: severe OA).27 Ten percentage of the radiographs were scored twice: correlation between both readings was used to establish intra-reader reliability [intra-class correlation hip radiographs: 99 % (95 % CI 85–93 %); intra-class correlation knee radiographs: 95 % (95 % CI 92–98 %)]. The second reading was used for further statistical analyses.The KL grade in our study was classified as KL 0–1 (no OA), KL 2 (mild OA) and KL 3–4 (severe OA).
Statistical analyses
Descriptive statistics were used to present the characteristics of patients and 8 their working status preoperatively and at follow-up. Comparisons of the baseline characteristics between working patients and patients who were not working at
the preoperative assessment were made by means of the Mann–Whitney U test
or Chi-square test. For all clinical outcome measures, change scores between the preoperative assessment and 1-year follow-up were computed with the 95 % confidence interval. Comparisons of working hours before and after surgery within the group of working patients were made by means of the Wilcoxon signedrank test. Sociodemographic and job characteristics and patient-reported outcomes (SF- 36, EQ-5D, EQ5D-VAS and HOOS/KOOS) were compared between patients who were working preoperatively and did return to work and patients who did not, by means of the Mann–Whitney U test or Chi-square test, where appropriate. All data were analyzed using the SPSS statistical package (version 20.0, SPSS, Chicago, Illinois).The level of statistical significance was set at p ≤ 0.05 for all analyses.
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