TKA need* | TKA readiness willingness† | Symptoms of depression‡ | TKA expectations§ | Estimate (95% CI) |
Low (n=207) | Moderate (n=106) | Moderate/severe (low appropriateness) (n=6) | Low (n=0) Moderate (n=4) High (n=2) | 44.4 (33.9 to 55.5) 53.9 (45.4 to 62.1) 63.0 (53.9 to 71.3) |
Mild (moderate appropriateness) (n=18) | Low (n=4) Moderate (n=6) High (n=8) | 65.7 (55.2 to 74.8) 73.6 (66.6 to 79.6) 80.3 (73.6 to 85.6) | ||
None (high appropriateness) (n=82) | Low (n=8) Moderate (n=33) High (n=41) | 46.9 (36.4 to 57.6) 56.3 (48.6 to 63.7) 65.2 (57.2 to 72.5) | ||
High (n=101) | Moderate/severe (n=8) | Low (n=3) Moderate (n=4) High (n=1) | 61.2 (48.4 to 72.7) 69.7 (59.2 to 78.4) 77.0 (66.9 to 84.8) | |
Mild (n=17) | Low (n=4) Moderate (n=5) High (n=8) | 42.1 (29.7 to 55.5) 51.4 (39.9 to 62.8) 60.7 (48.3 to 72.7) | ||
None (n=6) | Low (n=8) Moderate (n=35) High (n=33) | 63.5 (52.8 to 72.9) 71.7 (64.2 to 78.2) 78.7 (71.3 to 84.6) | ||
Moderate (n=611) | Moderate (n=173) | Moderate/severe (n=28) | Low (n=3) Moderate (n=15) High (n=10) | 58.1 (48.5 to 67.0) 66.9 (60.7 to 72.5) 74.7 (68.0 to 72.5) |
Mild (n=57) | Low (n=8) Moderate (n=33) High (n=16) | 76.8 (69.3 to 82.9) 82.8 (78.7 to 86.3) 87.6 (83.5 to 90.7) | ||
None (n=88) | Low (n=8) Moderate (n=47) High (n=33) | 60.4 (50.1 to 69.8) 69.0 (62.2 to 75.1) 76.5 (69.7 to 82.1) | ||
High (n=438) | Moderate/severe (n=114) | Low (n=15) Moderate (n=72) High (n=27) | 73.2 (65.0 to 80.0) 79.9 (74.7 to 84.3) 85.3 (79.9 to 89.4) | |
Mild (n=137) | Low (n=17) Moderate (n=68) High (n=52) | 55.7 (44.5 to 66.3) 61.2 (48.3 to 72.7) 69.7 (59.2 to 78.4) | ||
None (n=187) | Low (n=22) Moderate (n=89) High (n=76) | 75.0 (68.5 to 80.6) 81.4 (78.2 to 84.2) 86.5 (82.7 to 89.5) | ||
High (n=209) | Moderate (n=20) | Moderate/severe (n=10) | Low (n=0) Moderate (n=7) High (n=3) | 70.5 (59.3 to 79.7) 77.7 (69.6 to 84.2) 83.6 (76.2 to 89.0) |
Mild (n=4) | Low (n=0) Moderate (n=3) High (n=1) | 85.2 (77.7 to 90.4) 89.3 (84.5 to 92.7) 92.4 (88.4 to 95.1) | ||
None (n=6) | Low (n=0) Moderate (n=4) High (n=2) | 72.5 (60.1 to 82.2) 79.4 (70.3 to 86.2) 84.9 (77.0 to 90.4) | ||
High (n=189) | Moderate/severe (n=99) | Low (n=16) Moderate (n=63) High (n=20) | 82.5 (75.7 to 87.7) 87.3 (83.0 to 90.7) 90.9 (86.8 to 93.9) | |
Mild (n=50) | Low (n=6) Moderate (n=24) High (n=20) | 68.5 (56.5 to 78.4) 76.0 (66.9 to 83.2) 82.2 (73.7 to 88.4) | ||
None (n=39) | Low (n=6) Moderate (n=22) High (n=11) | 83.9 (77.5 to 88.7) 88.3 (84.5 to 91.3) 91.7 (88.1 to 94.3) |
*TKA need was considered low if WOMAC Pain Score and KOOS-PS were in the lowest tertiles of preoperative scores (WOMAC Pain Score≤45 and KOOS-PS≤44), high if both scores were in the uppermost tertiles (WOMAC Pain Score≥60 and KOOS-PS≥62) and moderate otherwise.
†Readiness/willingness was considered high if knee symptoms were unacceptable and the individual indicated definite willingness for TKA and moderate otherwise.
‡Symptoms of depression were categorised as per PHQ-8 recommendations: no depressed mood (high appropriateness) if ≤4, mild depressed mood (moderate appropriateness) if 5–9 and moderate/severe depressed mood (low appropriateness) if ≥10.
§TKA expectations that were positively associated with our TKA outcome in our multivariable regression model (improved ability to go upstairs and perform recreational activities) were considered ‘realistic’, while those that were negatively associated with our outcome (improved ability to kneel or improved psychological well-being) were considered ‘unrealistic’. For each participant, we assigned an expectation score of 1 for each realistic expectation deemed ‘very important’ and a score of −1 for each unrealistic expectation indicated as ‘very important’. Participant expectation scores were then summed (−2 to +2) and appropriateness was considered to be low if the summary score was <0 (preponderance of unrealistic expectations), moderate if 0 and high if >0, indicating a preponderance of realistic expectations.
KOOS-PS, Knee injury and Osteoarthritis Outcome Score physical function short-form; PHQ-8, Patient Health Questionnaire; TKA, total knee arthroplasty; WOMAC, Western Ontario-McMaster Universities OA Index.