Background : Segmental spinal instability after a laminectomy, and adjacent segment disease (ASD) at after an arthrodesis, are well-known concerns in spinal surgery, which may require re-interventions, usually by surgical arthrodesis, posing the problem of a new heavy intervention under general anesthesia, in often fragile patients.

Trans-facet fixation (TFF) under local anesthesia and double fluoroscopic and CT guidance is a minimally invasive technique involving the placement of screws through the posterior facet joints, improving spinal stability.

Purpose : The aim of our study is to evaluate the efficacy, in terms of pain reduction (VAS) and improvement of daily activities (ODI), of TFF under CT scan guidance in the context of low back pain and/or radiculalgia related to focal instability secondary to laminectomy or ASD.

Methods : TFF were performed in 24 patients having a history of spinal surgery such as laminectomy and/or classic surgical arthrodesis and remaining symptomatic, at Nice University Hospital between 2017 and 2021 Pre- and postoperative pain and disability levels were measured using the visual analogue scale (VAS) and the Oswestry Disability Index (ODI), collected prospectively at systematic 6-month and 1-year follow-up visits. Long term evolution were assessed by phone consultation.

Inclusion criterias : - Patients treated at Nice University Hospital between 2017 and 2021 by transfacet arthrodesis,

• History of spinal surgery ( laminectomy and/or classic arthrodesis) - Clinical signs of subsequent instability(low back pain and/or radiculopathy).
• MRI or scintigraphy signs of instability or ASD :
• Spondylolisthesis appeared or increased on successive exams
• Facet dislocation
• Subchondral bone changes of the vertebral endplates (Modic 1)
• Insufficient improvment after epidural and posterior joint corticosteroid infiltrations

All patients treated at Nice University Hospital between 2017 and 2021 by transfacet arthrodesis, with history of spinal surgery ( laminectomy and/or classic arthrodesis), andsigns of subsequent instability.