New surgical techniques have been developed to minimize perioperative damage to paravertebral stabilizing musculotendinous system. Among them, midline lumbar fusion (MIDLF) shows to be a viable option. With data on MIDLF remaining scarce, we assessed its long-term clinical and radiological effects.
In our prospective cohort study, patients having undergone MIDLF for degenerative spinal instability were evaluated. Before and after operation, subjects were clinically and radiologically examined. Peri- and postoperative complications were recorded. Follow-up period was two years. Statistical analysis was performed, with p ≤ 0.05 considered significant.
Sixty-four patients (average age 58.9 ± 10.7 years, 41 [64.1%] women) were included. The most frequent indication for MIDLF was degenerative spondylolisthesis grade I (28 cases, 43.8%), the prevalent spinal segment to be fused was L4/5 (35 cases, 54.7%). Mean duration of surgery was 148.2 ± 28.9 minutes. Relief of lower back pain (LBP) and leg pain (LP) was significant and stable in the postoperative period, as assessed by visual analog scale (VAS; p ˂ 0.001). On aggregate, 86.9% subjects reported fair, good, or excellent outcomes in terms of pain relief on MacNab score 2 years after surgery. Patients´ level of function in activities of daily living improved significantly: from Oswestry disability index (ODI) 66.8 ± 9.8 before to 33.9 ± 16.5 two years after surgery (p ˂ 0.001). On X-ray and CT scans at 12 months, interbody fusion occurred in 46 patients (73.4%), 13 cases (20.3%) were inconclusive, and in 4 cases (6.3%) there was no fusion. No damage to the neural or vascular structures and no failure of hardware or screw loosening were recorded.
MIDLF is an efficient and safe method for surgical treatment of lumbar spine instability. Its limited invasiveness contributes to better preservation of paravertebral muscles, and thus to enhanced postoperative spinal stability.

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