Table 6.

Anteroposterior (AP) diameter of spinal canal at disc level in the neutral, flexion, and extension position

	ND	DD	BD	HD
Neutral position
T12/L1	15.89±2.82	15.40±2.78	15.45±2.79	14.67±3.27
L1/2	15.32±2.22	15.58±2.67	15.02±2.61	14.78±2.87
L2/3	15.08±2.67	15.06±3.04	14.10±2.84	13.52±2.53
L3/4	14.90±2.59	14.72±2.95	13.48±3.02	13.27±3.01
L4/5	14.60±2.29	14.64±2.81	13.31±2.87	13.16±3.08
L5/S1	15.17±3.14	14.61±2.68	14.08±3.08	13.93±2.18
Flexion position
T12/L1	15.36±3.01	15.50±2.77	14.88±2.58	14.72±1.87
L1/2	15.18±2.69	15.76±3.13	14.71±2.79	14.16±1.94
L2/3	15.10±3.13	15.35±3.06	14.35±2.84	14.19±2.03
L3/4	14.88±2.66	15.08±2.91	14.10±3.01	13.81±3.01
L4/5	15.28±2.39	15.02±2.98	14.09±2.84	13.43±3.12
L5/S1	15.74±2.64	15.18±2.94	14.51±2.91	13.84±2.69
Extension position
T12/L1	15.32±2.14	15.66±2.11	16.51±12.14	14.62±2.78
L1/2	15.21±2.59	15.46±2.54	15.63±10.92	14.40±2.88
L2/3	14.18±2.83	14.56±2.71	14.45±10.14	13.63±2.89
L3/4	13.68±2.39	13.94±2.73	13.52±8.05	12.66±3.15
L4/5	13.57±2.28	13.44±2.51	12.80±3.98	12.06±3.07
L5/S1	14.78±2.65	14.13±2.53	13.99±5.10	13.00±2.39

Note: Data presented as mean ± SD (mm) and P<0.05 was considered statistically significant.

Abbreviations: BD, bulging discs; DD, degenerative discs; HD, herniated discs; ND, normal discs.