Table 2 Potential indicators of patellofemoral and tibiofemoral joint OA considered in the current study

Risk factors

Age; sex

1^st degree relative with arthritis; previous menisectomy; contralateral TKR

In-clinic face-to-face interview

Body mass index

In-clinic measurement

Clinical hand OA

In-clinic self-complete questionnaire + physical examination

Clinical history/symptoms

Time since problem onset; gradual onset; problem started following injury; bilateral knee pain; incident pain; duration of morning stiffness; inactivity gelling; reported swelling in past month; reported dramatic swelling ever; locking; giving way

In-clinic face-to-face interview

Pain days in last six months‡; pain, stiffness, aching on most days in the past month; current pain intensity (0 to 10 NRS)‡; significant interference with daily activities in last six months‡;

In-clinic self-complete questionnaire

Whole leg pain; pain walking on a flat surface†; stiffness on waking†; difficulty descending stairs†

Prior postal self-complete questionnaire¶

Physical signs

Intercondylar gap in standing; intermalleolar gap in standing; PFJ glide/compression test; presence and severity of palpable knee effusion; fixed flexion deformity; bony enlargement; mediolateral instability; isometric knee extensor strength; isometric knee flexor strength; coarse crepitus; knee flexion ROM; TF joint line tenderness; multiple local tender points§; timed single-leg standing balance

In-clinic physical examination