Unilateral Biportal Endoscopic Lumbar Interbody Fusion: A Technical Note and an Outcome Comparison with the Conventional Minimally Invasive Fusion

Figures & data

Figure 1 (A and B) Location of incision at the level of the pedicle. (C) Triangulation of working and viewing portal above the lamina. (D) Waterflow from the working portal.

Figure 2 (A) Working position using unilateral biportal endoscopy. (B) Flavectomy piece by piece using Kerrison punch. (C) Contralateral decompression.

Figure 3 (A) Annulotomy using an annular cutter. (B) Preparation of endplate. (C) Endplate removal completed (asterisk).

Figure 4 (A) Insertion of reamer under fluoroscopic view. (B) Confirmation on image intensifier.

Figure 5 (A) Cage insertion under endoscopic view. (B) Confirmation on image intensifier.

Figure 6 After pedicle screw insertion from AP (A) and lateral (B) view.

Table 1 General Characteristic of Degenerative Spondylolisthesis Patients Underwent Operations

	Conventional MIS-TLIF	ULIF	Mean Difference (CI 95%)	P-value
	N=73	N=72
Age, years–means (SB)	52.3 (6.13)	55.1 (5.12)	4.5 (−1.9–10.9)	0.160
Sex				0.130
Male	28 (37.5)	26 (62.5)
Female	45 (63.2)	46 (36.8)
Body Mass Index (BMI), kg/m^2 –means (SB)	24.8 (3.42)	23.6 (3.67)	1.2 (−1.2–3.7)	0.319
BMI Category				0.494
Normal	39 (40.0)	40 (60.0)
Overweight	30 (66.7)	29 (33.3)
Obese	4 (57.1)	3 (42.9)
Smoking History				0.227
Yes	11 (36.4)	17 (63.6)
No	62 (58.3)	55 (41.7)
Operation Level				0.586
L3–4	10 (11.42)	8 (10.52)
L4–5	48 (65.71)	56 (81.57)
L5–S1	15 (22.85)	8 (7.89)

Table 2 Comparison of Visual Analog Scale Between Conventional MIS TLIF and ULIF

	Conventional MIS TLIF N=73	ULIF N=72	Mean Difference (CI 95%)	P-value
Visual analog scale
Back
Pre operation	5.4	5.7	0 (−1–1)	0.708
Post operation
Directly	3.9	2.7	0 (−1–1)	0.032
3 months	2.4	1.9	0 (−1–1)	0.046
6 months	1.6	1.7	0 (−1–1)	0.660
12 months	0.9	0.8	0 (0–1)	0.386
Leg
Pre operation	4.5	4.6	0 (−1–1)	0.909
Post operation
Directly	4.6	4.6	0 (0–1)	0.700
3 months	3.6	3.7	0 (0–1)	0.773
6 months	1.8	2.1	1 (0–1)	0.603
12 months	0.8	0.7	1 (0–2)	0.067

Table 3 Comparison of ODI Between Conventional MIS TLIF and ULIF

	Conventional MIS TLIF	ULIF	Mean Difference (CI 95%)	P value
	N=73	N=72
Oswestry Disability Index
Pre operation	62 (56.5–70.5)	60 (52–63.5)	6 (−2–14)	0.103
Post operation
Directly	54 (37–49)	41 (49–60.5)	11 (−3–17)	0.045
3 months	16 (5.5–14.5)	12 (8–32.5)	−4 (−12–2)	0.232
6 months	12 (4–12.5)	8 (4–19)	−2 (−8–4)	0.483
12 months	8 (1.5–10)	6 (3.5–17.5)	−3 (−10–2)	0.184

Table 4 Comparison of SF-36 Score Between MIS TLIF and ULIF

SF-36	3 Months			6 Months			12 Months
	Conventional MIS TLIF	ULIF	P value	Conventional MIS TLIF	ULIF	P value	Conventional MIS TLIF	ULIF	P value
PF	66.5±4.9	65.2±4.1	0.067	70.3±5.4	71.5±4.9	0.071	73.3±5.0	69.4±4.9	0.070
RFP	57.4±7	37.4±6.8	0.078	72.4±6.9	63.5±7.0	0.073	68.9±6.9	66.3±7.1	0.075
Bodily pain	55.8±4.1	53.5±3.7	0.066	61.8±4.3	64.5±7.9	0.086	65.7±5.4	66.4±6.7	0.088
General health	65.6±3.9	61.2±3.2	0.079	66.8±4.8	67.9±5.4	0.081	73.8±4.9	75.4±6.9	0.069
Vitality	76.3±5.9	59.5±4.2	0.088	69.5±3.7	72.4±5.1	0.075	73.3±4.6	73.4±5.7	0.083
SRF	75.6±5.4	78.3±5.1	0.083	87.6±5.0	88.4±6.7	0.089	82.4±5.9	83.4±5.3	0.086
ERF	75.6±6.5	70.5±8.3	0.072	84.5±3.4	83.8±2.1	0.076	93.3±5.3	92.1±4.2	0.092
Mental health	77.2±3.5	70.3±4.5	0.075	77.4±3.5	79.3±4.5	0.062	83.2±4.3	82.1±6.3	0.068
PCS	42.8±12.6	40.2±11.5	0.077	43.5±9.6	44.5±7.2	0.055	48.0±11.0	48.7±7.3	0.077
MCS	51.6±12.9	48.6±12.9	0.079	50.6±12.1	51.3±5.6	0.086	55.1±13.8	54.8±10.4	0.088

Figure 7 Fusion rate comparison showed no significant difference between ULIF group (orange line) and the conventional MIS-TLIF group (blue line).