Page 103 - The value of total hip and knee arthroplasties for patients

Patients’ pre-operative general and specific outcome expectations predict postoperative pain and function after total knee and total hip arthroplasties
items of the HSS expectation surveys. For THA items about walking stairs, getting rid of limp, getting in or out of bed chair or car, be able to put on shoes and socks, improve ability to do daily activities in and around the house and improve ability to cut toenails were summed into an ‘expectations for function’ scale. For THA the sum of two items namely relieve of pain during the day, relieve of pain during the night was used as the ‘pain expectations’ scale. Because this variable was highly skewed it was dichotomized in ≤6 and >7 points. For TKA the items about being able to stretch the knee, walking stairs, kneeling down, traveling with public transportation, improving ability to do daily activities in and around the house and being able to change position (sitting down, getting up etc.) were summed into an ‘expectations for function’ scale. For TKA the HSS expectation survey only contains one pain item which was used as ‘pain expectations’ scale, this item was highly skewed and therefore it was dichotomized in ≤3 and 4 points.
Pain and function 6 Pain and function were measured both pre-operatively and 12 months post-
operatively with Dutch version of the Knee injury and Osteoarthritis Outcome
Score (KOOS) [37] and the Hip injury and Osteoarthritis Outcome Score (HOOS)
[38] pain and ADL subscales. The pain subscales consists of respectively 9 (KOOS) and 10 (HOOS) items and the ADL subscales consist of 17 items. Sum scores for each subscale are transformed to a 0–100 scale, with 0 representing extreme problems and 100 representing no problems[39] [38].
Mental health
Mental health was measured with the Short Form 36 (SF-36), from which the Mental Component Score (SF-36 MCS) was calculated[40;41] . Scores range from 0-100 with a higher score representing better mental health.
Preoperative radiological severity
Preoperative supine radiographs of hips (anterior-posterior) and weight-bearing radiographs of the knee (posterior-anterior) were collected from the patients’ medical record. Radiographs were assessed by an experienced radiologist who was blinded for the side of operation and patient characteristics.The Kellgren and Lawrence (KL) grading system was used to classify the severity of OA. 10% of the radiographs were scored twice: the Intra-Class Correlation of the hip radiographs was 99% (95% CI: 85-93%); the Intra-Class Correlation of the knee radiographs was
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