Table 2: Distribution of treated levels.

InstrumentationLevelNumber of patients

1-level ( )L3-43 (4.2%)
L4-523 (31.9%)
L5-S1 5 (6.9%)

2-levels ( )L2-3-41 (1.4%)
L3-4-533 (45.8%)
L4-5-S1 7 (9.7%)