Table 3. Success, return to work, and ASD rate following C-ADR versus fusion from two FDA trials with follow-up of 48 months or more.^*.

	Burkus et al1 (2010), 60 mo			Sasso et al2 (2011), 48 mo
	C-ADR	Fusion	P	C-ADR	Fusion	P
Overall success†	–	–		85.1% (154/181)	72.5% (100/138)	.004
NDI success‡	–	–		90.6% (164/181)	79.0% (109/138)	.003
Neurological success§	95.0% (137/144)	88.9% (113/127)	NS	92.8% (167/180)	89.9% (124/138)	NS
ASD rate	2.9% (8/276)	4.9% (13/265)	NS	4.1% (10/242)	4.1% (9/221)	NS
Working	76.3% (110/144)	72.6% (92/127)	NS	74.7% (135/181)	67.9% (123/181)	NS

^*ASD indicates adjacent segment disease; C-ADR, cervical artificial disc replacement; FDA, US Food and Drug Administration; NDI, Neck Disability Index; and NS, not statistically significant.

^†Composite measure in which patients had to achieve all the following: an improvement of ≥15 points on NDI, neurological improvement, no serious (WHO grade 3 or 4) adverse events related to the implant or surgical implantation procedure, and no subsequent surgery or intervention that would be classified as treatment failure.

^‡Improvement of ≥15 points in NDI from baseline.

^§Defined as maintenance or improvement of all three neurological parameters (motor and sensory function, and reflexes).