. 2020 Dec 10;15:595. doi: 10.1186/s13018-020-02081-y

Table 1.

Characteristics of included studies

Author	Study NO.	Number of patient	Gender ratio (male/female)	Mean age (years)	Mean follow-up duration (months)	Cause of TM	Comorbidity	Type of OPLL/OLF			Severe lesions
Author	Study NO.	Number of patient	Gender ratio (male/female)	Mean age (years)	Mean follow-up duration (months)	Cause of TM	Comorbidity	Single	Multiple but not fusion	Fusion	T1–T5	T5–T9	T9–TL1
Wang et al.	1	33	1.20	55.03	70.82	OLF	DM 2 + CM 2 + LM 11	16			9	4	52
Wang et al.	2	18	0.38	56.2	31.2	OLF	DO 11	5	0	13	1	6	33
Li et al.	3	85	0.57	60.2	49.2	OLF	DM 9				22	19	44
Hou et al.	4	427	1.42	53		OLF 309 + OPLL 120 + DH 129	CM 61 + LM 47
Onishi et al.	5	73	1.70	61.9	70.2	OLF 55 + OPLL 25 + DH 8	DM16				11	18	44
Hitchon et al.	6	44	2.14	66	16		CM 13 + LM 6
Uehara et al.	7	35	1.91	70.5	44	OLF 20 + OPLL 6 + DH 1					4	1	30
Uehara et al.	7	15	1.50	63.5	46.1	OLF 5 + OPLL 4 + DH 3 + AS 3					0	1	14
Yang et al.	8	21	0.90	52.1	24.5	OPLL		11	3	7	27	11	3
Onishi et al.	9	15	0.87	65.5	45	OLF 15 + OPLL 15	DM 4				3	10	2
Wang et al.	10	23	0.84	39.8		OLF 99 + OPLL 66 + DH 17
Wang et al.	10	145	0.84	39.8		OLF 99 + OPLL 66 + DH 17
Li et al.	11	11	0.57	50.2	21.2	OLF 11 + OPLL 9	DO 8				19	22	24
He et al.	12	283	1.62	51.8		OLF 123 + OPLL 73 + DH 54 + DISH 19					49	60	174
Ma et al.	13	23	1.55	34.7	4.6		DO 5
Kawaguchi et al.	14	41	3.10	59.4	66	OLF	DM 11
Yang et al.	15	38	1.37	59	46.1	OLF		6	32			23	13
Nie et al.	16	18	0.80	56.3	35	OLF	DO 2		18
Liu et al.	17	13	0.62	56	36.8	OLF 13 + OPLL 13	DO 2
Li et al.	18	19	0.58	55.3	53.2	OLF	DM 2
Yu et al.	19	78	2.25	59.6		OLF		63	15			22
Yu et al.	19	78	2.25	59.6		OLF		63	15				15
Gao et al.	20	75	1.34	54.7	35.7	OLF	CM 12 + LM 7		75
Li et al.	21	7	0.75	56.7	74.4	OL 31F + OPLL 31
		11	0.83	56.8	52.8
		13	0.44	57.3	90.2
Sun et al.	22	266	1.37	54.3		OLF	DO 67
Yamazaki et al.	23	24	0.41	54.8	53	OPLL
Zhang et al.	24	11	2.66	54.5		OLF 11 + OPLL 11	CM 1
Chen et al.	25	16	1.66	57.5	57.3	OLF	CM 1 + LM 2				4	4	21
Matsuyama et al.	26	37		58		OPLL
Hur et al.	27	26	1.88	53	27.3	OLF		1	5	20	10	6	25
Zhong et al.	28	22	1.00	52.4	35.6	OLF	CM 4 + LM 3	3	8	11	2	1	14
Yoon et al.	29	40	1.85	57.08	17.3
Park et al.	30	12	0.50	60.5	24.2	OLF		10	2
Zhao et al.	31	13	1.16		13.3	OLF
Zhang et al.	32	56	2.29		24	OLF	DM 23 + DO 48	33	23			4	3
Zhang et al.	32	40	2.07		24	OLF	DM 23 + DO 48	20	29			3	5
Hirabayashi et al.	33	13	3.33	58		OLF
Takahata et al.	34	30	0.66	53	96	OLF	CM 15
Khoo et al.	35	13	0.63	51.8	12	DH

The blanks are not mentioned in the study

DM diabetes mellitus, DP dura ossification, CM cervical myelopathy, LM lumbar myelopathy