Nottmeier, Eric

BACKGROUND AND OBJECTIVES: Degenerative spine disease is a leading cause of disability, with increasing prevalence in the older patients. While age has been identified as an independent predictor of outcomes, its predictive value is limited for similar older patients. Here, we aimed to determine the most predictive frailty score of adverse events in patients aged 80 and older undergoing instrumented lumbar fusion. METHODS: We proceeded with a multisite (3 tertiary academic centers) retrospective review including patients undergoing instrumented fusion aged 80 and older from January 2010 to present. A composite end point encompassing 30-day return to operating room, readmission, and mortality was created. We estimated the area under the receiver operating characteristic curve for frailty scores (Modified Frailty Index-5 [MFI-5], Modified Frailty Index-11 [MFI-11], and Charlson Comorbidity Index [CCI]) in relation to that composite score. In addition, we estimated the association between each score and the composite end point by means of logistic regression. RESULTS: A total of 153 patients with an average age of 85 years at the time of surgery were included. We observed a 30-day readmission rate of 11.1%, reoperation of 3.9%, and mortality of 0.6%. The overall rate of the composite end point at 30 days was 25 (15.1%). The AUC for MFI-5 was 0.597 (0.501-0.693), for MFI-11 was 0.620 (0.518-0.723), and for CCI was 0.564 (0.453-0.675). The association between the scores and composite end point did not reach statistical significance for MFI-5 (odds ratio [OR] = 1.45 [0.98-2.15], P = .061) and CCI (OR = 1.13 [0.97-1.31], P = .113) but was statistically significant for MFI-11 (OR = 1.46 [1.07-2.00], P = .018). CONCLUSION: This is the largest study comparing frailty index scores in octogenarians undergoing instrumented lumbar fusion. Our findings suggest that while MFI-11 score correlated with adverse events, the predictive ability of existing scores remains limited, highlighting the need for better approaches to identify select patients at age extremes.

BACKGROUND: Graduate surgical education is highly variable across regions and institutions regarding case volume and degree of trainee participation in each case. Dedicated educational curriculum using cadaveric tissue has been shown to enhance graduate surgical training, however with associated financial and utility burden to the institution. OBJECTIVE: To investigate the utility of educational and cost applications of a novel method of combining mixed organic hydrogel polymers and 3-dimensional printed anatomic structures to create a complete “start-to-finish” simulation for resident education in spinal anatomy, instrumentation, and surgical techniques. METHODS: This qualitative pilot study investigated 14 international participants on achievement of objective and personal learning goals in a standardized curriculum using biomimetic simulation compared with cadaveric tissue. A questionnaire was developed to examine trainee evaluation of individual anatomic components of the biomimetic simulators compared with previous experience with cadaveric tissue. RESULTS: A total of 210 responses were acquired from 14 participants. Six participants originated from US residency education programs and 8 from transcontinental residency programs. Survey results for the simulation session revealed high user satisfaction. Score averages for each portion of the simulation session indicated learner validation of anatomic features for the simulation compared with previous cadaveric experience. Cost analysis resulted in an estimated savings of $10 833.00 for this single simulation session compared with previous cadaveric tissue sessions. CONCLUSION: The results of this study indicate a strong potential of establishing biomimetic simulation as a cost-effective and high-quality alternative to cadaveric tissue for the instruction of fundamental spine surgical techniques.

BACKGROUND: Management of degenerative disease of the spine has evolved to favor minimally invasive techniques, including nonrobotic-assisted and robotic-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Value-based spending is being increasingly implemented to control rising costs in the US healthcare system. With an aging population, it is fundamental to understand which procedure(s) may be most cost-effective. OBJECTIVE: To compare robotic and nonrobotic MIS-TLIF through a cost-utility analysis. METHODS: We considered direct medical costs related to surgical intervention and to the hospital stay, as well as 1-yr utilities. We estimated costs by assessing all cases involving adults undergoing robotic surgery at a single institution and an equal number of patients undergoing nonrobotic surgery, matched by demographic and clinical characteristics. We adopted a willingness to pay of $50 000/quality-adjusted life year (QALY). Uncertainty was addressed by deterministic and probabilistic sensitivity analyses. RESULTS: Costs were estimated based on a total of 76 patients, including 38 undergoing robot-assisted and 38 matched patients undergoing nonrobot MIS-TLIF. Using point estimates, robotic surgery was projected to cost $21 546.80 and to be associated with 0.68 QALY, and nonrobotic surgery was projected to cost $22 398.98 and to be associated with 0.67 QALY. Robotic surgery was found to be more cost-effective strategy, with cost-effectiveness being sensitive operating room/materials and room costs. Probabilistic sensitivity analysis identified robotic surgery as cost-effective in 63% of simulations. CONCLUSION: Our results suggest that at a willingness to pay of $50 000/QALY, robotic-assisted MIS-TLIF was cost-effective in 63% of simulations. Cost-effectiveness depends on operating room and room (admission) costs, with potentially different results under distinct neurosurgical practices.

AbstractIntroductionThree‐dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high‐resolution segmentation and 3D‐printingtechnique was investigated for the creation of a dynamic educational model.MethodsAn anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high‐resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3–7 vertebrae were 3D‐printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in‐vivo measurements. The flexible 3D‐printed model was then compared to a static 3D‐printed model to determine the educational benefit of demonstrating physiologic concepts.ResultsThe canal diameter changes on the flexible 3D‐printed model accurately reflected in‐vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D‐printed model to a cohort of learners.ConclusionsDynamic 3D‐printed models can provide educators with a cost‐effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex‐vivo modeling of case‐specific physiologic and pathologic conditions.

AbstractIntroductionThree‐dimensional printing and virtual simulation both provide useful methods of patient‐specific anatomical modeling for assessing and validating surgical techniques. A combination of these two methods for evaluating the feasibility of spinal instrumentation techniques based on anatomical landmarks has not previously been investigated.Materials and MethodsNineteen anonymized CT scans of the thoracic spine in adult patients were acquired. Maximum pedicle width and height were recorded, and statistical analysis demonstrated normal distributions. The images were converted into standard tessellation language (STL) files, and the T12 vertebrae were anatomically segmented. The intersection of two diagonal lines drawn from the lateral and medial borders of the T12 transverse process (TP) to the lateral border of the pars and inferolateral portion of the TP was identified on both sides of each segmented vertebra. A virtual screw was created and insertion into the pedicle on each side was simulated using the proposed landmarks. The vertebral STL files were then 3D‐printed, and 38 pedicles were instrumented according to the individual posterior landmarks used in the virtual investigation.ResultsThere were no pedicle breaches using the proposed anatomical landmarks for insertion of T12 pedicle screws in the virtual simulation component. The technique was further validated by additive manufacturing of individual T12 vertebrae and demonstrated no breaches or model failures during live instrumentation using the proposed landmarks.ConclusionsEx vivo modeling through virtual simulation and 3D printing provides a powerful and cost‐effective means of replicating vital anatomical structures for investigation of complex surgical techniques.

Abstract We present a surgical video highlighting the technical demonstration and microsurgical anatomy of an L4-5 transforaminal lumbar interbody fusion utilizing a combination of thermoplastic polymers and 3-dimensional printing technology to create a biomimetic lumbar spine surgical simulator. The posterior elements of L4-5 and the inferior portion of L3 are exposed in their entirety, including the transverse processes in order to identify the appropriate landmarks for pedicle screw insertion. The interspinous ligament of L4-5 is removed, and an interlaminar spreader is used to distract the facet joint. An inferior L4 facetectomy is performed for local autograft harvesting. The L4 and L5 pedicles are skeletonized to completely open the foramen in order to ensure that the exiting nerve root will not be compromised during cage insertion. The ligamentum flavum is then removed, exposing the common thecal sac and L5 traversing root. The L4 exiting nerve root is then identified, completing Kambin's triangle and location of the disc space. The disc is incised, and a combination of punches and curettes are used to completely remove the disc. After an interbody trial is used to assess the proper cage size, the cage is packed with graft and inserted into the midline of the disc space. Pedicle screws are then placed using an anatomic freehand technique, and intraoperative fluoroscopy is performed in order to evaluate the instrumentation and interbody position. If a contralateral decompression is required, a facet-sparing technique is performed in order to preserve bony surface for the fusion. Patient consent was not required for this simulation video.

Anatomical knowledge is a key tenet in graduate medical and surgical education. Classically, these principles are taught in the operating room during live surgical experience. This puts both the learner and the patient at a disadvantage due to environment, time, and safety constraints. Educational adjuncts such as cadaveric courses and surgical skills didactics have been shown to improve resident confidence and proficiency in both anatomical knowledge and surgical techniques. However, the cost‐effectiveness of these courses is a limiting factor and in many cases prevents implementation within institutional training programs. Anatomical simulation in the form of “desktop” three‐dimensional (3D) printing provides a cost‐effective adjunct while maintaining educational value. This article describes the anatomical and patient‐centered approach that led to the establishment of our institution's 3D printing laboratory for anatomical and procedural education. Clin. Anat. 32:124–127, 2019. © 2019 Wiley Periodicals, Inc.

Abstract We present a surgical video highlighting the technical pearls for C7 pedicle screw placement with respect to cervicothoracic constructs. Pedicle screw placement into C7 has been shown to enhance the biomechanical stability of both cervical and cervicothoracic constructs and is safe for patient related outcomes. 1 , 2 Rod placement across the cervicothoracic junction is known to be difficult because of the variable starting point of the C7 pedicle screw, which may cause misalignment of the polyaxial heads with respect to the C7 and C6 screw heads. Using our step-wise method of anatomic screw placement, this potential pitfall is minimized. The T1 pedicle screw is placed first. The C6 lateral mass screw starting point is displaced slightly superiorly from the midpoint of the lateral mass in order to make room for the polyaxial head of the C7 pedicle screw. A small laminotomy is performed in order to find the medial border of the C7 pedicle. Palpation of the medial border allows for an approximation of the pedicle limits. The cranial-caudal angle of drilling is perpendicular to the C7 superior facet, and the medial-lateral trajectory typically falls between 15 and 20 degrees medial. Once the pedicle is cannulated, a ball-tipped probe is used to confirm intraosseous position. A rod is cut and contoured to the appropriate length of the construct. The C7 pedicle screw should capture the rod easily with slight displacement of the polyaxial head. Postinstrumentation anteroposterior and lateral fluoroscopy are performed to confirm good position of the lateral mass and pedicle screws. Patient consent was not required for this cadaveric surgical video.