Objective To describe the initial clinical and radiological results of a minimally invasive technique of lumbar fusion

Study Design Prospective review of 16 consecutive patients with degenerative lumbar disease who underwent a mini posterior lumbar interbody fusion using the operating microscope and B- twin expandable cages and titanium facet screws and facet fusion .

Subjects 16 patients with degenerative lumbar disease, average age 41(33–48) 5 male 11 female. This was the primary procedure in 11 patients , 5 had previously had a microdiscectomy . 14 patients L5/S1 level 2 patients 2 level L4/L5 L5/S1

Outcome Measures Oswestry disability index and VAS of back and leg pain were perfomed pre-operatively and at 3/12, 6/12, 12/12 Average follow up was 8.1 months (3–17).

Results 1 patient had persistent bone graft donor site pain ,no other complications. Preoperative mean ODI 55 (40–76) Post operative ODI 33 (2–64) Pre op back pain 7.1 (0–8) post op at last follow up 3.7(0–6) Pre op leg 3.9 (0–8) 1.6(0–5) All patients who had reached 12 months follow up had evidence of bone formation at the level in question. All patients improved in terms back pain and leg pain scores and all but 1 patient had a significantly improved ODI score.

Conclusions This has proved to be a safe method of achieving a 360degree stabilisation and probable fusion. It maximally preserves the paraspinal muscles and their innervation in contrast to posterolateral fusion and conventional PLIF using pedicle screws .The small diameter of the implant prior to expansion minimises the degree of neural retraction required .