Changes in spino-pelvic alignment after surgical treatment of isthmic spondylolisthesis.

BACKGROUND AND PURPOSE: To analyze the changes in spino-pelvic parameters after surgical treatment of lumbar isthmic spondylolisthesis. MATERIALS AND METHODS: Sixty patients recruited from a group of consecutive series of 128 cases with isthmic spondylolisthesis operated on between 2002 and 2012 in the Department of Neurosurgery, Tarnow, Poland. All patients were operated on by the same surgeon (the first author). Spino-pelvic parameters: PI, SS, PT, LSA, and LL were measured manually on standing lateral view radiograms. Patients were divided according to Spinal Deformity Study Group classification which we modified for means of analysis: (A) low-grade group: subgroups with balanced pelvis and unbalanced pelvis (instead of normal and high PI subgroups), (B) high-grade group: subgroups with balanced and unbalanced pelvis. RESULTS: Twenty-nine patients had unbalanced pelvis before the operation. In 10 of them (34%), the procedure resulted in full correction of pelvis position meaning that they achieved balanced pelvis after the surgery. There were 6 patients with low-grade slip who had balanced pelvis preoperatively but showed unbalanced pelvis after the surgery but this loss of balanced pelvis did not affect the clinical outcome which overall was good among them. Patients with unbalanced pelvis presented changes towards restoration of spino-sacro-pelvic anatomy postoperatively: PT decreased while SS increased, although these changes were not statistically significant. CONCLUSION: Further studies are needed to confirm whether surgical correction of spino-pelvic parameters results in better clinical outcome in patients with isthmic spondylolisthesis.

Posterior keyhole corpectomy with percutaneous pedicle screw stabilization in the surgical management of lumbar burst fractures.

OBJECTIVE: The authors present a new method of minimally invasive surgical management of lumbar burst fractures through the posterior approach. The method includes minimally invasive corpectomy and interbody fusion, both of which are performed through a keyhole approach, and percutaneous pedicle screw fixation of the fracture. The technique of the posterior keyhole corpectomy presented in this report is a novel and original concept of the first author (AM). The percutaneous pedicle screw stabilization is performed with the use of a percutaneous instrumentation system (Sextant; Medtronic, Inc., Minneapolis, MN). The Sextant system has been dedicated and used in nontrauma degenerative cases; the novel aspect of this system is its application in spine fractures. Indications for the method include Denis classification subtype B or Magerl subtype A.3.1 burst fractures. Both subtypes represent fractures with failure and retropulsion of the upper part of the vertebral body. METHODS: The clinical experience of this study includes four cases of burst fractures with significant retropulsion and occlusion of the spinal canal. Long-term results were assessed at a minimum follow-up period of 1 year (maximum, 3.5 yr). The follow-up assessments included: 1) the quality of decompression and reconstruction of the spinal canal (computed tomographic and magnetic resonance imaging scanning); 2) the stability of the operated segment (dynamic x-rays); 3) the quality of interbody fusion (computed tomographic scanning and dynamic x-rays); and 4) correction of the fracture kyphosis and its postoperative loss (measurements of Cobb angles for the assessment of sagittal plane deformity). The minimum armamentarium requirements for this method include a typical micro lumbar discectomy retractor set; a surgical microscope; two-plane intraoperative fluoroscopy; and a system for percutaneous pedicle screw stabilization (Sextant). "Posterior keyhole corpectomy" indicates corpectomy of the posterior upper half of the vertebral body or removal of the retropulsed bone fragment via two keyhole skin incisions on both sides of the spinous process (each skin incision measures 2 to 3 cm long). Exposure of the retropulsed fragment (the posterior upper part of the vertebral body) is achieved by medial or complete facetectomy along with complete or medial resection of the pedicle. This has to be performed bilaterally. Percutaneous stabilization requires four additional stab skin incisions. RESULTS: We observed no surgery-related complications (neurological, hardware, dural tears, or deep or superficial wound infections); there was perfect decompression and clearance of the spinal canal (confirmed by computed tomographic and magnetic resonance imaging scanning); and there was solid stability at the affected segments (confirmed by dynamic x-rays). Healed fusion was noted in all patients but one. The latter patient had no clinical symptoms of spinal instability. Kyphotic deformity was corrected and reversed into lordosis in three patients. Loss of deformity correction was noted in all patients; however, all patients retained lordotic alignment of the affected segment. CONCLUSION: The advantages of this method include sparing the posterior elements (lamina, spinous process, supraspinous and interspinous ligaments, and paravertebral muscles), safety of the decompression provided by the use of a surgical microscope, and perfect illumination of the operating field. The drawbacks of the method include limitation to certain types of burst fractures, the method is surgically demanding, and the method requires development of a special retractor system to eliminate the cumbersome alternate insertion and the reinsertions of the typical microdiscectomy retractor set.

[Minimally invasive posterior corpectomy of the lumbar spine with transpedicular fixation]. / Minimalnie inwazyjna korpektomia tylna odcinka ledzwiowego kregoslupa ze stabilizacja przeznasadowa

The authors present their experience in the minimally invasive posterior keyhole lumbar corpectomy with transpedicular stabilization. This technique involves the removal of the posterior part of the affected vertebral body with the pedicle screw fixation through four 2-3 cm long skin incisions on the back. Two cephalad skin incisions provide an approach for corpectomy and instrumentation of the upper pedicles of the construct. Two caudal skin incisions provide an approach for instrumentation of the lower pedicles of the construct. The minimum armamentarium requirement includes classic micro lumbar discectomy retractor set and intraoperative fluoroscopy. According to the authors' best knowledge this is the first minimally invasive posterior keyhole lumbar corpectomy ever reported in the literature (2002). This is also the first minimally invasive transpedicular fixation ever performed in Poland (2002). This technique was presented during EANS Congress (Lisbon, September 2003). Some reports have recently appeared in the literature on percutaneous pedicle screw fixation of the lumbar spine in non traumatic cases. A special instrumentarium system (Sextant by Medtronic) has been developed and used in this type of minimally invasive stabilization. Although this system has not been dedicated for spine fractures it is feasible in trauma cases. We have one case of L2 burst fracture fixed percutaneously with Sextant.