Introduction: We investigate the clinical outcome in a series of patients with degenerative spondylolisthesis treated by extended unilateral mini-open TLIF approach, which allows ipsilateral radicular decompression as well as central canal and contralateral nerve roots decompression. The efficacy of decompression has been evaluated by radiological volumetric analysis.
Methods: 123 patients (51 men, mean age 64.2, range 40-77) affected by symptomatic lumbar canal stenosis associated to degenerative spondylolisthesis, at the same level, underwent microsurgical decompression of canal stenosis and interbody fusion through mini open- TLIF approach. Patients experienced both radiculopathy and neurogenic claudication. The surgical control of contralateral neural structures has been obtained by adequate table tilting, microscope inclination and oblique position of tubular retractor. 84 pts received TLIF at one level, 39 at two levels. Only 32 of 123 patients (12 men) completed both clinical and radiological follow-up schedule. Mean follow-up was 19.3 months (range 6-58). Radiological evaluation was based on preoperative Magnetic Resonance (MR), Computed Tomography (CT) and plain and flexion/extension x-rays.Volumetric evaluation of extent of decompression was based on manual segmentation and rendering of the spinal canal volume on pre- and post-operative CT-scans.
VAS (back and leg), ODI and SF-36 (physical and mental status) were used for clinical assessment.
Results: A statistically significant (p < 0.05) clinical improvement has been demonstrated comparing pre- and post-operative values of ODI, VAS back and leg. 647 screws were percutaneously implanted: seven screws (0,01%) were malpositioned, in 3/7 cases re-operation was required. Six patients had CSF leak (four of them required reparative surgery). Four patients experienced infectious complications.
Mean spinal canal volume changed from 4.49 cm3 (range 2.2-9.9) to 6.40 (range 2.9-13.1) cm3, with a mean 45% increase.
Conclusions: A significant increase of spinal canal size is achievable through a unilateral approach. The change of spinal canal volume is directly related to the improvement of clinical parameters.
Patient Care: The volumetric evaluation of spinal decompression may be useful to identify a threshold to objectively evaluate the efficacy of surgery at affected level.
Learning Objectives: 1. To understand the importance of volumetric evaluation to quantify spinal decompression
2. To investigate the feasibility of bilateral neural decompression obtained by unilateral approach
3. To analyze and quantify the efficacy of mini-Open TLIF in surgical management of symptomatic central stenosis of lumbar canal