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Table 2 Univariate analysis of risk factors for aseptic loosening after revision total knee arthroplasty

From: Influence of extension stem length and diameter on clinical and radiographic outcomes of revision total knee arthroplasty

Potential risk factorLoosening (n = 17)No loosening (n = 48)OR95% CIp
Age, years69.2271.940.950.87–1.020.188
Female sex8394.881.47–16.130.009*
Bone defect severity
Femur (loosening, n = 12)
  I3280.290.07–1.220.075
  IIa925   
Tibia (loosening, n = 12)
 I1260.090.01–0.780.005*
 IIa1127   
Prosthesis before revision
 Primary TKA14432.280.86–6.010.094
 UKA03   
 Revision TKA31   
 None01   
Stem length, mm
 Femur100 (75–200)100 (25–200)0.9900.96–1.010.990
 Tibia75 (25–150)100 (25–200)0.980.96–1.010.157
Radiographic finding
 Alignment, °5.0 (2.1–6.2)5.8 (5.2–7.4)0.620.43–0.870.006*
Femur (loosening, n = 12)
 CFR0.858.33 (1/12)52.83 (28/53)0.080.01–0.670.020*
 CFR0.7 > 2 cm16.67 (2/12)75.47 (40/53)0.070.01–0.330.001*
 CFR0.7 > 4 cm8.33 (1/12)45.28 (24/53)0.110.01–0.910.041*
 CFRmax0.69 (0.54–1.00)0.82 (0.47–1.00)0.940.89–0.980.010*
 CFR0.85 length0.0 (0.0–4.7)1.2 (0.0–7.8)0.370.13–0.970.045*
 CFR0.7 length0.0 (0.0–7.5)3.5 (0.0–10.3)0.500.31–0.790.003*
Tibia (loosening, n = 12)
 CFR0.858.33 (1/12)47.17 (25/53)0.100.01–0.840.034*
 CFR0.7 > 2 cm41.67 (5/12)77.36 (41/53)0.210.05–0.770.020*
 CFR0.7 > 4 cm16.67 (2/12)58.49 (31/53)0.140.02–0.710.018*
 CFRmax0.77 (0.60–0.88)0.82 (0.53–1.00)0.960.91–1.010.159*
 CFR0.85 length0.0 (0.0–1.7)0.0 (0.0–12.8)0.400.15–1.070.069*
 CFR0.7 length1.6 (0.0–4.3)4.5 (0.0–4.7)0.700.52–0.940.019*
  1. Data are shown as frequency (number/total) or median (interquartile range) unless otherwise specified. Bone defect severity was assessed using the Anderson Orthopaedic Research Institute classification. Alignment indicates the femoral-tibial angle. CFR was calculated as the ratio between the stem width and the medullary canal width. CFRx stands for CFR > x. CFRx > y indicates the stem length > y for CFR larger than x. CFRx length indicates the stem length for which CFR > x. CFRmax indicates the maximum CFR over the entire length of the stem. CI, confidence interval; CFR, canal filling ratio; OR, odds ratio; TKA, total knee arthroplasty; UKA, uni-compartment knee arthroplasty; *: p < 0.05