Table 3.
Results from univariable and multivariable regression analyses with dependent variable IPFF (yes/no)
| IPFF n (%) | Unadjusted RR (99% CI) | Adjusted a RR (99% CI) | Adjusted b RR (99% CI) | Adjusted c RR (99% CI) | Adjusted d RR (99% CI) | |
|---|---|---|---|---|---|---|
| Sex | ||||||
| Male | 469 (0.7) | 1 (ref) | 1 (ref) | 1 (ref) | ||
| Female | 1693 (1.2) | 1.8 (1.5-2.1) | 1.8 (1.5-2.1) e | 1.9 (1.6-2.2) | ||
| Age | ||||||
| < 50 | 268 (2.1) | 2.2 (1.7-2.9) | 2.3 (1.8-2.9) e | 1.2 (1.0-1.5) | ||
| 50-59.99 | 384 (1.4) | 1.5 (1.2-2.0) | 1.6 (1.2-2.0) e | 1.1 (1.0-1.4) | ||
| 60-69.99 | 561 (0.9) | 1 (ref) | 1 (ref) | 1 (ref) | ||
| 70-79.99 | 598 (0.8) | 0.9 (0.7-1.0) | 0.9 (0.7-1.1) e | 1.0 (0.9-1.2) | ||
| 80-89.99 | 320 (1.1) | 1.2 (1.0-1.5) | 1.3 (1.0-1.6) e | 1.4 (1.2-1.7) | ||
| ≥ 90 | 31 (2.4) | 2.5 (1.5-4.2) | 2.6 (1.6-4.3) e | 2.3 (1.4-3.6) | ||
| Diagnosis | ||||||
| Primary OA | 1209 (0.8) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | |
| Other | 953 (1.9) | 2.5 (2.1-2.8) | 2.5 (2.2-2.9) | 2.2 (1.9-2.6) e | 1.7 (1.4-2.1) | |
| Previous surgery | ||||||
| No | 1624 (0.9) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) |
| Yes | 538 (2.5) | 2.8 (2.3–3.3) | 2.8 (2.4–3.3) | 2.5 (2.1–3.0) | 1.8 (1.5–2.2) e | 1.8 (1.5–2.2) |
| Surgical approach | ||||||
| Lateral | 1289 (1.2) | 1.5 (1.1-1.9) | 1.6 (1.1-2.3) | 1.5 (1.1-2.2) | 1.5 (1.1-2.1) | 1.5 (1.1-2.0) e |
| Posterior | 618 (0.8) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) |
| Anterior | 248 (1.2) | 1.5 (1.0-2.2) | 1.4 (0.9-2.1) | 1.4 (0.9-2.0) | 1.5 (1.0-2.1) | 1.3 (0.9-1.8) e |
| Other | 7 (3.1) | 3.9 (1.2-13.1) | 4.1 (1.2-14) | 4.0 (1.2-14) | 3.6 (1.1-12) | 3.0 (1.0-8.9) e |
| Fixation technique | ||||||
| Cemented | 908 (0.7) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) |
| Cementless | 1254 (1.6) | 2.2 (1.5-3.2) | 2.7 (1.9-3.8) | 2.7 (2.0-3.7) | 2.7 (2.0-3.7) | 2.7 (2.0-3.6) e |
| Operation year | ||||||
| 1987-1995 | 462 (1.2) | 1 (ref) | 1 (ref) | |||
| 1996-2000 | 226 (0.9) | 0.7 (0.5-1.0) e | 0.7 (0.5-1.0) | |||
| 2001-2005 | 247 (0.8) | 0.7 (0.4-1.0) e | 0.7 (0.4-1.0) | |||
| 2006-2010 | 341 (1.0) | 0.9 (0.6-1.2) e | 0.7 (0.5-1.0) | |||
| 2011-2015 | 470 (1.3) | 1.0 (0.7-1.6) e | 0.8 (0.5-1.1) | |||
| 2016-2020 | 416 (0.9) | 0.8 (0.5-1.1) e | 0.7 (0.5-1.1) | |||
N = 210,256 (of which 2,162 IPFF).
a
Adjusted for operation year (in groups)
b
Adjusted for operation year, age (groups), and sex.
c
Adjusted for operation year, age, sex, and diagnosis.
d
From full model, all variables included.
e
Indicate estimates of total effect after adjustment for measured confounders (Figure 2, see Supplementary data).
IPFF = intraoperative periprosthetic femoral fracture; OA = osteoarthritis; RR = relative risk.