Table 4: Comparison of disc signal change between young age and old age.

VariablesTotalAgeP values
<65-year
old
≧65-year old

Number of patients723735
Screw loosening
per patient
Yes 168 (21.6%)8 (22.9%)0.900
No5629 (78.4%)27 (77.1%)
Screw loosening
per screw
Yes199 (4.8%)10 (5.5%)0.739
No351179 (95.2%)172 (94.5%)
CDS of bridged disc
Pre-op60.2 ± 25.258.9 ± 24.762.1 ± 26.10.732
Post-op66.9 ± 26.0**67.6 ± 28.7**65.9 ± 22.20.800

Mean values are presented ± SD.
** P < 0.05, the post-op value compared with the pre-op value demonstrated significant difference.
CDS: calibrated disc signal.