REGULAR ARTICLE Bilateral tubular minimally invasive surgery for low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS): analysis of a series focusing on postoperative sagittal balance and review of the literature Giuseppe M. V. Barbagallo • Mario Piccini • Abdulrazzaq Alobaid • Abdulaziz Al-Mutair • Vincenzo Albanese • Francesco Certo Received: 28 August 2014 / Revised: 3 September 2014 / Accepted: 3 September 2014 / Published online: 17 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Purpose To report our early experience with minimally invasive surgery (MIS) in low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS), and to analyze the impact of surgery on postoperative spino-pelvic and sacro-pelvic parameters. Methods Eight patients (mean age 47.6 years) underwent MIS for LDLLS involving in all but one the L5–S1 level. VAS and ODI were used for clinical assessment. Imaging included pre-operative X-rays, CT and MRI scans. Post- operatively, all patients underwent X-rays and CT-scans. Pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) values as well as lumbar lordosis (LL) have been derived from pre- and post-operative standard X-rays. Results Mean follow-up is 30.12 months (range 15–42). No complications related to the surgical procedure were observed. Patients reported a satisfactory clinical outcome, as demonstrated by variation in mean VAS (from 9.1 to 3.6) and ODI (from 70.50 to 28.25 %) scores. Comparison between pre- and post-operative sacro-pelvic parameters documented moderate changes, with reduction of PT and increase of SS in all but one patient. Overall sagittal bal- ance of the spine has been evaluated using the sagittal vertical axis (SVA), obtained from post-operative X-rays. Mean value of SVA demonstrated a good sagittal balance of the spine. Conclusion This series demonstrates that MIS is feasi- ble and effective for LDLLS, as witnesses by the satis- factory clinical results maintained at medium-term follow-up. We submit that TLIF is a valid option but an adequately sized and positioned interbody cage is a key factor to allow satisfactory restoration of segmental lordosis. Keywords Cage Á Lumbar spine Á Minimally invasive surgery Á Sagittal balance Á Spondylolysis Á Spondylolisthesis Introduction Lumbosacral lytic spondylolisthesis (LLS) is a frequent disease, occurring in about 4-6 % of the population [10]. L5–S1 is the most involved level (95 % of the cases), whereas LSS occurring at L4–L5 level is less frequent. LLS is associated with a bony discontinuity of the ver- tebra’s pars interarticularis, the so-called spondylolysis, and the missing bone is replaced by fibrous connective and chondroid tissue bridging together the vertebral body and the posterior vertebral arch [26]. Several causes accounting for the onset of the bony defect have been proposed, including a stress or fatigue fracture of the pars interar- ticularis itself [8, 40]. A genetic predisposition for spon- dylolysis has also been postulated: the local low cortical bone density of the pars interarticularis has been related to an increased susceptibility to stress fractures [7]. Imaging of the LLS is based on X-ray and computed tomography (CT). Only 20 % of pars defects seen on plain radiography are identified on lateral oblique views, sug- gesting that oblique views do not add significant informa- tion. Several studies demonstrated superior sensitivity of G. M. V. Barbagallo (&) Á M. Piccini Á V. Albanese Á F. Certo Neurosurgery Department, Policlinico ‘‘G. Rodolico’’ University Hospital, Viale XX Settembre 45, 95129 Catania, Italy e-mail: giuseppebarbagal@hotmail.com; gbarbagallo@unict.it A. Alobaid Á A. Al-Mutair Department of Spine Surgery, Al-Razi Hospital, Kuwait, Kuwait 123 Eur Spine J (2014) 23 (Suppl 6):S705–S713 DOI 10.1007/s00586-014-3543-0