Variables considered as measures of TKA appropriateness criteria
| Patient appropriateness construct | Measure of assessment |
| TKA need | |
| Evidence of knee OA on clinical and radiographic examination of the joint being considered for surgery | Confirmed by surgeon post consultation in all participants. |
| Patient reports that knee OA symptoms are negatively impacting their overall quality of life | Knee pain: 5-item WOMAC pain subscale Likert V.3.0 (0–20, higher scores indicate greater pain). Knee (lower extremity) function: 7-item Knee injury and Osteoarthritis Outcome Score physical function short-form (0–100, higher scores indicate worse function). Perceived arthritis coping: 4-item Arthritis Coping Efficacy Scale (4–20, higher scores indicate better perceived arthritis coping). |
| An adequate trial of non-surgical OA treatment has been provided | Prior OA treatment: Participants were asked to indicate if they had ‘ever’ tried (yes/no): exercise—formal or informal; physiotherapy; weight loss; acetaminophen; anti-inflammatories; codeine; joint injection; and walking aids. Individuals were considered to have received recommended OA therapies if they had ‘ever tried’ formal exercise or physiotherapy and weight loss if overweight/obese and any analgesic. |
| TKA readiness/willingness | |
| The patient is ready and willing to have surgery | Patient Health Questionnaire Depression Scale (PHQ-8): This 8-item scale assesses depressive symptoms; total score from 0 to 24, with higher scores indicating more depressive symptoms. Patient Acceptable Symptom State: “Think about all the ways your knee OA has affected you during the last 48 hours. If you were to remain in the next few months as you were the last 48 hours would this be acceptable or unacceptable to you?” TKA willingness: “Based on your current understanding of the risks and benefits of knee replacement surgery and the severity of your knee arthritis, what is your current preference regarding having TKA?” Response options: 1, ‘would definitely not consider surgery now’, to 5, ‘would definitely consider surgery now’. |
| TKA expectations | |
| The patients’ expectations for knee replacement surgery are reasonable and thus achievable | Hospital for Special Surgery Knee Expectations Questionnaire: For each of 17 TKA outcomes, participants asked “How important are these expectations in the treatment of your knee arthritis?” Response options were: 4, very important, 3, somewhat important, 2, a little important, 1, I do not expect this, or 0, this does not apply to me. Summary score 0–100, with higher scores indicating a greater number of ‘very important’ TKA expectations. Expectations were: relieve knee pain, enjoy psychological well-being, and improve ability to perform daily activities, go upstairs, walk, squat, kneel, change position, for example, get up from a chair, straighten knee/leg, exercise or participate in sports, engage in sexual activity, participate in recreational activities, work for pay, interact with others, for example, care giving, walk without aids, take public transit or drive. |
| Health status | |
| Patient and surgeon agree that the potential risks associated with surgery do not outweigh potential benefits | Body mass index, kg/m2: calculated from reported height and weight. Comorbidity: for a list of ten common conditions, subjects indicated if they had the condition and, if so, if they were receiving treatment. Other troublesome lower extremity joints: participants indicated on a joint homunculus which joints were painful, swollen, tender or stiff. Smoking status: self-reported smoking status (never, past, current). |
OA, osteoarthritis; TKA, total knee arthroplasty; WOMAC, Western Ontario-McMaster Universities OA Index.