Table 1

Summary of data abstraction from each identified study.

Characteristic	Variable Type	Choices/Comment
Study design	Binary	Prospective vs retrospective
Procedure type	Nominal	Transiliac (either lateral or posterolateral) or posterior interpositional
Device/allograft used	Nominal	Name of device
Number of patients treated	Integer
Number of patients with follow-up scores	Integer
Baseline and last follow-up pain score (visual analog scale or numeric pain rating scale)	Continuous	Converted to 0- to 10-point scale
Baseline and last ODI	Continuous	For both pain score and ODI, when multiple scheduled follow-up visits were available, the last available reported mean score was extracted.
Safety outcomes: Symptomatic implant malposition—typically resulting in new onset acute radicular pain—requiring surgical intervention. Symptomatic implant malposition causing bowel/bladder perforation. Implant breakage. Implant migration. Late removal—typically for ongoing or recurrent pain. Dislodgement of bone fragment into foramen during placement. Fracture (sacral or ilial) during placement. Wound infection requiring notable treatment such as wound exploration or implant removal. Bleeding requiring surgical intervention.	Integer	Fracture defined as involving both cortices of the ilium or sacrum and displacement of a significant fragment of bone.