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Camilo A. Molina, Nicholas Theodore, A. Karim Ahmed, Erick M. Westbroek, Yigal Mirovsky, Ran Harel, Emanuele Orru’, Majid Khan, Timothy Witham and Daniel M. Sciubba

OBJECTIVE

Augmented reality (AR) is a novel technology that has the potential to increase the technical feasibility, accuracy, and safety of conventional manual and robotic computer-navigated pedicle insertion methods. Visual data are directly projected to the operator’s retina and overlaid onto the surgical field, thereby removing the requirement to shift attention to a remote display. The objective of this study was to assess the comparative accuracy of AR-assisted pedicle screw insertion in comparison to conventional pedicle screw insertion methods.

METHODS

Five cadaveric male torsos were instrumented bilaterally from T6 to L5 for a total of 120 inserted pedicle screws. Postprocedural CT scans were obtained, and screw insertion accuracy was graded by 2 independent neuroradiologists using both the Gertzbein scale (GS) and a combination of that scale and the Heary classification, referred to in this paper as the Heary-Gertzbein scale (HGS). Non-inferiority analysis was performed, comparing the accuracy to freehand, manual computer-navigated, and robotics-assisted computer-navigated insertion accuracy rates reported in the literature. User experience analysis was conducted via a user experience questionnaire filled out by operators after the procedures.

RESULTS

The overall screw placement accuracy achieved with the AR system was 96.7% based on the HGS and 94.6% based on the GS. Insertion accuracy was non-inferior to accuracy reported for manual computer-navigated pedicle insertion based on both the GS and the HGS scores. When compared to accuracy reported for robotics-assisted computer-navigated insertion, accuracy achieved with the AR system was found to be non-inferior when assessed with the GS, but superior when assessed with the HGS. Last, accuracy results achieved with the AR system were found to be superior to results obtained with freehand insertion based on both the HGS and the GS scores. Accuracy results were not found to be inferior in any comparison. User experience analysis yielded “excellent” usability classification.

CONCLUSIONS

AR-assisted pedicle screw insertion is a technically feasible and accurate insertion method.

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Jennifer E. Kim, John Pang, Joani M. Christensen, Devin Coon, Patricia L. Zadnik, Jean-Paul Wolinsky, Ziya L. Gokaslan, Ali Bydon, Daniel M. Sciubba, Timothy Witham, Richard J. Redett and Justin M. Sacks

OBJECT

Total en bloc sacrectomy is a dramatic procedure that results in extensive sacral defects. The authors present a series of patients who underwent flap reconstruction after total sacrectomy, report clinical outcomes, and provide a treatment algorithm to guide surgical care of this unique patient population.

METHODS

After institutional review board approval, data were collected for all patients who underwent total sacrectomy between 2002 and 2012 at The Johns Hopkins Hospital. Variables included demographic data, medical history, tumor characteristics, surgical details, postoperative complications, and clinical outcomes. All subtotal sacrectomies were excluded.

RESULTS

Between 2002 and 2012, 9 patients underwent total sacrectomy with flap reconstruction. Diagnoses included chordoma (n = 5), osteoblastoma (n = 1), sarcoma (n = 2), and metastatic colon cancer (n = 1). Six patients received gluteus maximus (GM) flaps with a prosthetic rectal sling following a single-stage, posterior sacrectomy. Four required additional paraspinous muscle (PSM) or pedicled latissimus dorsi (LD) fasciocutaneous flaps. Three patients underwent multistage sacrectomy with an anterior-posterior approach, 2 of whom received pedicled vertical rectus abdominis myocutaneous (VRAM) flaps, and 1 of whom received local GM, LD, and PSM flaps. Flap complications included dehiscence (n = 4) and infection (n = 1). During the 1st year of follow-up, 2 of 9 patients (22%) were able to ambulate with an assistive device by the 1st postoperative month, and 6 of 9 (67%) were ambulatory with a walker by the 3rd postoperative month. By postoperative Month 12, 5 of 9 patients (56%)—or 5 of 5 patients not lost to follow-up (100%)—were able to able to ambulate independently.

CONCLUSIONS

The authors' experience suggests that the GM and pedicled VRAM flaps are reliable options for softtissue reconstruction of total sacrectomy defects. For posterior-only operations, GM flaps with or without a prosthetic rectal sling are generally used. For multistage operations including a laparotomy, the authors consider the pedicled VRAM flap to be the gold standard for simultaneous reconstruction of the pelvic diaphragm and obliteration of dead space.

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Kaisorn L. Chaichana, Mohamad Bydon, David R. Santiago-Dieppa, Lee Hwang, Gregory McLoughlin, Daniel M. Sciubba, Jean-Paul Wolinsky, Ali Bydon, Ziya L. Gokaslan and Timothy Witham

Object

Posterior lumbar spinal fusion for degenerative spine disease is a common procedure, and its use is increasing annually. The rate of infection, as well as the factors associated with an increased risk of infection, remains unclear for this patient population. A better understanding of these features may help guide treatment strategies aimed at minimizing infection for this relatively common procedure. The authors' goals were therefore to ascertain the incidence of postoperative spinal infections and identify factors associated with postoperative spinal infections.

Methods

Data obtained in adult patients who underwent instrumented posterior lumbar fusion for degenerative spine disease between 1993 and 2010 were retrospectively reviewed. Stepwise multivariate proportional hazards regression analysis was used to identify factors associated with infection. Variables with p < 0.05 were considered statistically significant.

Results

During the study period, 817 consecutive patients underwent lumbar fusion for degenerative spine disease, and 37 patients (4.5%) developed postoperative spine infection at a median of 0.6 months (IQR 0.3–0.9). The factors independently associated with an increased risk of infection were increasing age (RR 1.004 [95% CI 1.001–1.009], p = 0.049), diabetes (RR 5.583 [95% CI 1.322–19.737], p = 0.02), obesity (RR 6.216 [95% CI 1.832–9.338], p = 0.005), previous spine surgery (RR 2.994 [95% CI 1.263–9.346], p = 0.009), and increasing duration of hospital stay (RR 1.155 [95% CI 1.076–1.230], p = 0.003). Of the 37 patients in whom infection developed, 21 (57%) required operative intervention but only 3 (8%) required instrumentation removal as part of their infection management.

Conclusions

This study identifies that several factors—older age, diabetes, obesity, prior spine surgery, and length of hospital stay—were each independently associated with an increased risk of developing infection among patients undergoing instrumented lumbar fusion for degenerative spine disease. The overwhelming majority of these patients were treated effectively without hardware removal.

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Nasir A. Quraishi, Jean-Paul Wolinsky, Ali Bydon, Timothy Witham and Ziya L. Gokaslan

Myxopapillary ependymomas rarely present as a primary intrasacral lesion, and extensive sacral osteolysis is unusual. The authors report a case series of 6 patients with these complex tumors causing extensive sacral destruction, who underwent resection, lumbopelvic reconstruction, and fusion. The operative procedure, complications, and outcome are summarized after a mean follow-up of 3.55 years (range 18–80 months).