Risk-benefit analysis of navigation techniques for vertebral transpedicular instrumentation: a prospective study.

BACKGROUND CONTEXT: Pedicle screws in spinal surgery have allowed greater biomechanical stability and higher fusion rates. However, malposition is very common and may cause neurologic, vascular, and visceral injuries and compromise mechanical stability. PURPOSE: The purpose of this study was to compare the malposition rate between intraoperative computed tomography (CT) scan assisted-navigation and free-hand fluoroscopy-guided techniques for placement of pedicle screw instrumentation. STUDY DESIGN/SETTING: This is a prospective, randomized, observational study. PATIENT SAMPLE: A total of 114 patients were included: 58 in the assisted surgery group and 56 in the free-hand fluoroscopy-guided surgery group. OUTCOME MEASURES: Analysis of screw position was assessed using the Heary classification. Breach severity was defined according to the Gertzbein classification. Radiation doses were evaluated using thermoluminescent dosimeters, and estimates of effective and organ doses were made based on scan technical parameters. METHODS: Consecutive patients with degenerative disease, who underwent surgical procedures using the free-hand, or intraoperative navigation technique for placement of transpedicular instrumentation, were included in the study. RESULTS: Forty-four out of 625 implanted screws were malpositioned: 11 (3.6%) in the navigated surgery group and 33 (10.3%) in the free-hand group (p<.001). Screw position according to the Heary scale was Grade II (4 navigated surgery, 6 fluoroscopy guided), Grade III (3 navigated surgery, 11 fluoroscopy guided), Grade IV (4 navigated surgery, 16 fluoroscopy guided), and Grade V (1 fluoroscopy guided). There was only one symptomatic case in the conventional surgery group. Breach severity was seven Grade A and four Grade B in the navigated surgery group, and eight Grade A, 24 Grade B, and one Grade C in free-hand fluoroscopy-guided surgery group. Radiation received per patient was 5.8 mSv (4.8-7.3). The median dose received in the free-hand fluoroscopy group was 1 mGy (0.8-1.1). There was no detectable radiation level in the navigation-assisted surgery group, whereas the effective dose was 10 µGy in the free-hand fluoroscopy-guided surgery group. CONCLUSIONS: Malposition rate, both symptomatic and asymptomatic, in spinal surgery is reduced when using CT-guided placement of transpedicular instrumentation compared with placement under fluoroscopic guidance, with radiation values within the safety limits for health. Larger studies are needed to determine risk-benefit in these patients.

Intervertebral Disc Repair by Allogeneic Mesenchymal Bone Marrow Cells: A Randomized Controlled Trial.

BACKGROUND: Degenerative disc disease often causes severe low-back pain, a public health problem with huge economic and life quality impact. Chronic cases often require surgery, which may lead to biomechanical problems and accelerated degeneration of the adjacent segments. Autologous mesenchymal stromal cells (MSC) treatments have shown feasibility, safety and strong indications of clinical efficacy. We present here a randomized, controlled trial using allogeneic MSC, which are logistically more convenient than autologous cells. METHODS: We randomized 24 patients with chronic back pain diagnosed with lumbar disk degeneration and unresponsive to conservative treatments into 2 groups. The test group received allogeneic bone marrow MSCs by intradiscal injection of 25 × 10 cells per segment under local anesthesia. The control group received a sham infiltration of paravertebral musculature with the anesthetic. Clinical outcomes were followed up for 1 year and included evaluation of pain, disability, and quality of life. Disc quality was followed up by magnetic resonance imaging. RESULTS: Feasibility and safety were confirmed and indications of clinical efficacy were identified. MSC-treated patients displayed a quick and significant improvement in algofunctional indices versus the controls. This improvement seemed restricted to a group of responders that included 40% of the cohort. Degeneration, quantified by Pfirrmann grading, improved in the MSC-treated patients and worsened in the controls. CONCLUSIONS: Allogeneic MSC therapy may be a valid alternative for the treatment of degenerative disc disease that is more logistically convenient than the autologous MSC treatment. The intervention is simple, does not require surgery, provides pain relief, and significantly improves disc quality.

Heterotopic Ossification in Cervical Disk Surgery Is Still a Problem. What Are the Key Factors for a Solution?

BACKGROUND: The aim of our study was to determine the presence of heterotopic ossifications (HO) in a series of patients with cervical disk arthroplasty treated with different type of prosthesis, as well as to analyze the most suitable systems for diagnosis. METHODS: A retrospective study of patients with cervical disk disease treated with cervical arthroplasty between May 2005 and December 2009, was performed. Patients were divided into 3 groups, depending on the prosthesis implanted: (Group A: Baguera prosthesis, Group B: ProDisc prosthesis, and Group C: PCM prosthesis). The presence of heterotopic ossifications was evaluated with both, simple radiology and computed tomography. RESULTS: As a summary of the results on motion preservation, computed tomography scans showed that 63% of the cervical arthroplasties in Group A presented good mobility at the first check point (December 2010), whereas cervical arthroplasties in Group B and Group C had 74% and 65% severe motion restrictions, respectively (Grade III or Grade IV, according to McAfee classification). The differences between groups were statistically significant when comparing Groups A and B, and Groups A and C (P < 0.05), but there were no differences between Groups B and C (P < 0.05). At the second check point (December 2014), the good mobility was just preserved in the 26% of the disk replacements (all in Group A). CONCLUSIONS: Our results showed that, although cervical disks provide optimal mid-term results, the incidence of HO seems to increase with time. Long term studies, with a larger sample size should be conducted to evaluate the appearance of HO and cervical motion after total disk replacement.