Table 2.

Study characteristics

Study	Recruitment period	Number of cervical levels	Followup (years)	US FDA IDE trial	Single/multicenter (number of sites)
Park et al. [33]	NR	1 only	1	Yes	Multicenter (23)
Nabhan et al. [30]	Jan 2006–August 2007	1 only	1	No	Single center
Mummaneni et al. [26]	Oct 2002–August 2004	1 only	2	Yes	Multicenter (32)
Riina et al. [36]	NR	1 only	2	No	Single center
Heller et al. [17]	May 2002–October 2004	1 only	2	Yes	Multicenter (30)
Murrey et al. [28]	August 2003–October 2004	1 only	2	Yes	Multicenter (13)
Coric et al. [8]	NR	1 only	2	Yes	Multicenter (21)
Zhang et al. [48]	May 2004–May 2006	1 only	2	No	Multicenter (3)
Nabhan et al. [31]	April 2004–May 2005	1 only	3	No	Single center
Cheng et al. [7]	December 2004–September 2006	1, 2, or 3 levels	3	No	Single center
Sasso et al. [38]	May 2002–October 2004	1 only	4	Yes	Multicenter (30)
Delamarter et al. [9]	Aug 2003–October 2004	1 only	4	Yes	Multicenter (13)
Burkus et al. [3]	October 2002–August 2004	1 only	5	Yes	Multicenter (32)

IDE = investigational device exemption.