Table 2.

Characteristics of the included randomised controlled trials and baseline data

Author, year country	Participants	Definition of DS	Surgical approach	Outcomes	Risk of bias domains	FU (months)	Interventions	Sample size	Age (years), mean (SD)	Gender (female), n (%)	Degree of vertebral slip (mm), mean (SD)	Dynamic instability, n (%)	VAS-back, mean (SD)	VAS-leg, mean (SD)
Austevoll, et al 2021 NORDSTEN-DS trial Norway24	18–80 years; neurogenic claudication or radicular radiating pain in the lower limbs that had not responded to at least 3 months of conservative care; LSS; DS≥3 mm Mix of stable and instable	Dynamic instability—slippage of at least 3 mm, or at least 10 degrees of angulation, as assessed by dynamic standing radiographs	Posterior decompression (with or without preservation of midline structures) was used, followed by implantation of pedicle screws with rods and bone grafting across the level of spondylolisthesis, with optional use of an intervertebral fusion device	ODI, ZCQ, NRS back and leg, EQ-5D-3L, duration of surgery and length of hospital Stay, complications and reoperations and the percentage of patients who responded that their condition was ‘much worse’ or ‘worse than ever’ on the Global Perceived Effect scale	True randomisation of 1:1 ratio Allocation: computer-generated, stratified according to centre in blocks of 4–6 Blinding: patients likely not blinded; Investigators (outcome assessment) blinded Modified intention-to-treat analysis: all patients who received the trial treatment in accordance with the randomisation with available data (with imputations for missing data)	3, 24	D	133	66.0±7.4	92 (69.2)	7.6 (3.2)	35 (26)	6.7±2.0	6.6±2.0
							DF	129	66.5±7.9	88 (68.2)	7.2 (2.8)	27 (21)	6.7±2.1	6.7±2.1
Försth, et al 2016 Sweden28	LSS with or without DS (only those with DS used in this review); 50 and 80 years Mix of stable and instable (not measured)	Conventional lateral radiography (flexion–extension radiographs were not obtained); forward slip ≥3 mm	Method determined by surgeon	ODI, EQ-5D, VAS back and leg, ZCQ, patient reported outcomes (satisfaction), 6 min walk test		24 and 60	D	68	67 (7)	56 (82.4)	7.4 (2.8)	–	6.3 (2.4)	6.5 (2.2)
							DF	67	68 (7)	51 (76.1)	7.4 (2.6)	–	6.4 (2.0)	6.4 (2.1)
Ghogawala, et al 2016 SLIP trial USA27	DS, grade I, LSS and neurogenic claudication with or without lumbar radiculopathy; only stable (motion≤3 mm)	3–14 mm (mean 1.3 and 1.6)	Posterolateral instrumented fusion (a lumbar laminectomy as well as implantation of pedicle screws and titanium alloy rods across the level of listhesis, with a bone graft harvested from the iliac crest)	SF-36 physical component, ODI, complications and reoperations, blood loss, operative time, and length of stay		12, 24 and 48	D	35	66.5 (8.0)	27 (77)	6.5 (2.3)	–	–	–
							DF	31	66.7 (7.2)	26 (84)	5.6 (2.2)	–	–	–
Inose, et al 2018 Japan26	One level LSS with DS at the L4/5 level Mix of stable and instable	>3 mm of spondylolisthesis of the L4 vertebra on a plain lateral radiograph Dynamic instability—change of >10 degrees of angulation or >4 mm of translation of the vertebrae between flexion and extension of the spine	Posterolateral fusion with autogenous iliac bone graft and pedicle screw fixation	JOA, VAS back and leg, duration of operation, blood loss, duration of postoperative hospital stay and major intraoperative and perioperative complications, degree of progression of slippage (>5%) at postoperative year 5		12, 60, 144	D	29	63.4 (8.6)	12 (41)	6.5 (2.2)	12 (41)	5.28 (3.11)*	6.21 (2.3)*
							DF	31	61.2 (6.7)	20 (65)	8.1 (3.8)	13 (42)	6.28 (3.01)*	7.68 (2.51)*

*Unpublished data from authors.

D, decompression only; DF, decompression with fusion; DS, degenerative spondylolisthesis; EQ-5D, European Quality of Life–5 Dimensions; FU, follow-up; JOA, Japanese Orthopaedic Association score; LSS, lumbar spinal stenosis; NRS, numeric rating scale; ODI, Oswestry Disability Index; SF-36, Short Form 36 Health Survey Questionnaire; VAS, visual analogue scale; ZCQ, Zurich Claudication Questionnaire.