Table 1.

Characteristics of Studies Included in Second Surgery Analysis.

Study	Study Design	Inclusion Criteria	Exclusion Criteria	Sponsor	Definition of Second Surgery	Arm	Sample Size	Technical Details	Age (mean and standard deviation unless otherwise stated)	Sex	NDI reported
NCT00578812 Phillips et al 41	RCT	Single level degenerative disc disease with radiculopathy or myelopathy only affecting either levels C3-4 or C7-T1	Trauma, prior fusion, 2 or more levels affected, tumor, osteoporosis, daily insulin, etc.	NuVasive	Any revision, removal, reoperation, or supplemental fixation	ACDF	265	Single level ACDF with allograft and plate	43.9 range 22-73	46.0% male	Yes
						ADR	276	PCM Cervical Disc	43.3 range 25-72	46.4% male	Yes
ISRCTN44347115 Macdowall et al 42	RCT	Patient 25-60yo with cervical radiculopathy (arm pain) for at least 3 months and correlating MRI findings in 1 or 2 levels	Previous surgery, >2 levels requiring treatment, severe facet arthropathy, myelopathy, etc.	Stockholm County Council, DePuy Synthes Spine, Uppsala County Council, Swedish Society of Spinal Surgeons	Not stated	ACDF	70	ACDF with autogenous iliac crest graft and plate	47.0 ± 6.9	47.1% male	Yes
						ADR	81	Discover ADR	46.7 ± 6.7	50.6% male	Yes
Lin et al. 2015 43	Retrospective cohort	Adult patients undergoing ACDF or laminoplasty diagnosed with multiple level cervical degenerative disease. From 2001 to 2011, query of Taiwan National Health Insurance Research Database (NHIRD), using diagnostic codes. Large national database including 99% of population according to paper.	Single level disease, tumor, any who had both procedures.	Not reported	Defined as another ACDF or laminoplasty within 1 year (short term) or more than 1 year (long term) after the index	ACDF	6605	Not reported	55.17 ± 14.18	65.42% male	No
						Laminoplasty	1578	Not reported	59.01 ± 14.05	66.29% male	No
Park et al. 201644,45	Retrospective cohort	CSM or radiculopathy diagnoses treated with ACDF, corpectomy, posterior fusion, laminoplasty. Performed using diagnostic code search on national level HIRA database.	Trauma, tumor, infectious spondylitis, inflammatory spondylitis of gout, rheumatoid arthritis, ankylosing spondylitis, ossification of posterior longitudinal ligament	Hallym University Research Fund 2014 (HURF-2014-28)	Any cervical reoperation excluding third and subsequent reoperation events	ACDF	8143	Not reported	51.44 ± 10.80 (all intervenions reported together)	61.29% male	No
						Laminoplasty	391	Not reported			No
						Laminectomy and Fusion	537	Not reported			No
Puvanesarajah 2017 46	Retrospective Cohort	ICD-9 diagnostic code database query for cervical spondylosis with myelopathy, subsequent query for surgical interventions of interest. Utilized fee-for-service patient database, PearlDiver Patient Records Database, which contains records for Medicare beneficiaries from 2005 to 2012.	Combined anterior posterior, revision, OC fusion, trauma, tumor, etc	No funding received	Revision surgery codes were searched in database including implant removal, revision fusion, incision and drainage, exploration, and hardware removal.	ACDF	34 867	1 to 2 level ACDF	Not reported	48.2% male (<65 years) 52.6% male (65-84 years)	No
						Laminectomy and Fusion	16 167	Not reported	Not reported	57.8% 1-2 level PCF <65yrs 59.7% 1-2 PCF 65-84yrs 57.7% >3 level PCF <65yrs 56% >3 level PCF 65-84yrs	No
Hashimoto et al. 2018 47	Prospective cohort	Cervical myelopathy with radiographic compression between C2-C7, data source from national-level registry focusing on Miyagi prefecture in Japan since 1988.	Not stated	No funding	Analysis only included reoperation for ‘neurological complications.’ Though analyzed, Kaplan-Meier curve excluded revision for surgical site infection	Laminoplasty	4208	Midline splitting (French door) laminoplasty using hydroxyapatite spacer in split laminae and cross-multiplied non-absorbable threads are used to stabilize the laminae	62 ± 11	68.75% male	No
Nakashima et al. 2020 49	Retrospective case series	Adults with clinical myelopathy with either CSM or OPLL on MRI or CT, all who underwent laminoplasty. Unspecified surgical database searched from 2003-2016.	Revision, infection, tumor, or trauma	Nagoya Spine Group research funds	Surgeries for late-onset myelopathy, paralysis, or severe radicular pain (6 months after laminoplasty) Reoperation for infection, epidural hematoma, or C5 palsy conducted immediately after surgery (<6 months after surgery)	Laminoplasty	623	Open door laminoplasty with gap bridged by local or artificial bone strut	Not reported	Not reported	No