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Karishma Parikh, Andre Tomasino, Jared Knopman, John Boockvar and Roger Härtl


The authors present their clinical results and the learning curve associated with the use of tubular retractors for 1- and 2-level lumbar microscope-assisted discectomies and laminectomies.


The study involves a retrospective and prospective analysis of 230 patients who underwent noninstrumented minimally invasive procedures for degenerative lumbar spinal disease between 2004 and 2007. Data on patient demographic characteristics and operative results, including length of stay, blood loss, operative times, and surgical complications were collected. Clinical outcomes were assessed based on pre- and postoperative Visual Analog Scale scores, Oswestry Disability Index values, and the Macnab outcome scale scores.


The results showed characteristic differences in blood loss and operating times between 1- and 2-level procedures and between discectomies and laminectomies. A significant learning curve was seen by a decrease in operating time for 1- level discectomies and 2-level laminectomies. Major complications were not observed.


The use of tubular retractors for microsurgical decompression of degenerative spinal disease is a safe and effective treatment modality. As with other techniques, minimally invasive procedures are associated with a significant learning curve. As surgeons become more comfortable with the procedure, its applications can be expanded to include, for example, spinal instrumentation and deformity correction.

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Christoph P. Hofstetter, Andrew R. James and Roger Härtl


Paracoccygeal transsacral fixation is a novel percutaneous technique for arthrodesis of L5–S1 and L4–5 (Axial Lumbar Interbody Fusion [AxiaLIF]). There are no reports on feasible revision strategies. The goal of this paper is to analyze the surgical details of failed AxiaLIF constructs and to describe revision strategies.


The medical charts, operative records, and imaging studies of 5 patients with failed multisegment instrumentation using the AxiaLIF device were reviewed.


AxiaLIF constructs were revised in 5 patients with a mean age of 58.4 years. All AxiaLIF devices were part of multisegment fusion constructs for revision surgery and were revised an average of 15 months after implantation. Two AxiaLIF devices were percutaneously retrieved; one because of excessive bone resorption around the AxiaLIF screw, and the other because of chronic hardware infection. In these 2 patients, the anterior column was subsequently stabilized via anterior lumbar interbody fusion. In the other 3 patients, the AxiaLIF device was left in situ. In 2 of these patients the anterior column was stabilized with bilateral L5–S1 posterior lumbar interbody fusion, and in the remaining patient with L4–5 instability the posterior instrumentation only was revised. Revision surgeries were well tolerated. One patient suffered from a wound dehiscence of the back wound.


AxiaLIF devices are safely retrieved using percutaneous technique. Both anterior and posterior revision strategies may be used to achieve anterior column fixation.

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Emanuele La Corte, Philipp R. Aldana, Paolo Ferroli, Jeffrey P. Greenfield, Roger Härtl, Vijay K. Anand and Theodore H. Schwartz


The endoscopic endonasal approach (EEA) provides a minimally invasive corridor through which the cervicomedullary junction can be decompressed with reduced morbidity rates compared to those with the classic transoral approaches. The limit of the EEA is its inferior extent, and preoperative estimation of its reach is vital for determining its suitability. The aim of this study was to evaluate the actual inferior limit of the EEA in a surgical series of patients and develop an accurate and reliable predictor that can be used in planning endonasal odontoidectomies.


The actual inferior extent of surgery was determined in a series of 6 patients with adequate preoperative and postoperative imaging who underwent endoscopie endonasal odontoidectomy. The medians of the differences between several previously described predictive lines, namely the nasopalatine line (NPL) and nasoaxial line (NAxL), were compared with the actual surgical limit and the hard-palate line by using nonparametric statistics. A novel line, called the rhinopalatine line (RPL), was established and corresponded best with the actual limit of the surgery.


There were 4 adult and 2 pediatric patients included in this study. The NPL overestimated the inferior extent of the surgery by an average (± SD) of 21.9 ± 8.1 mm (range 14.7-32.5 mm). The NAxL and RPL overestimated the inferior limit of surgery by averages of 6.9 ± 3.8 mm (range 3.7-13.3 mm) and 1.7 ± 3.7 mm (range −2.8 to 8.3 mm), respectively. The medians of the differences between the NPL and NAxL and the actual surgery were statistically different (both p = 0.0313). In contrast, there was no statistically significant difference between the RPL and the inferior limit of surgery (p = 0.4375).


The RPL predicted the inferior limit of the EEA to the craniovertebral junction more accurately than previously described lines. The use of the RPL may help surgeons in choosing suitable candidates for the EEA and in selecting those for whom surgery through the oropharynx or the facial bones is the better approach.