Table 2.

Reasons for exclusion.

Exclusion factors (not mutually exclusive)	Number with exclusion
Cervical diagnosis or procedures	4,268
Less than 3 months of surveillance	613
Trauma	354
Age > 65	332
Artificial disc replacement	217
Open treatment of fracture	174
Not an initial observed lumbar fusion admission	174
Congenital or other anomaly	154
Fracture or dislocation	85
Neurological impairment	57
Drug abuse	40
Cancer	34
Osteomyelitis	17
Dynamic stabilizing device	16
Spinal spacer	12
HIV or immune deficiency	7
Intraspinal abscess	4
Inflammatory spondylopathy	3
Spinal cord injury	1
Pregnancy	0
ANY OF ABOVE EXCLUSIONS	6,756