Optimal Targeting Display for Navigated Pelvic Screw Insertions

Surgical navigation can be used for complex orthopaedic procedures, such as iliosacral screw fix- ations, to achieve accurate and efficient results [11]. Although there have been studies studying the impact of navigation systems on surgical outcomes [6, 3], we are not aware of any studies that have quantified the effect of how information regarding the surgical navigation scene is displayed to surgeons on conventional monitors. However, the display of information can have a measurable effect on both accuracy and time required to perform the navigated surgery, as the surgical scene can be presented in many different formats [9]. Optimizing surgical accuracy potentially helps improves patient safety by reducing screw malplacement [11], while optimiz- ing time efficiency reduces opportunity cost [1]. Therefore, we designed a study to determine the optimal visualizations for performing navigated pelvic screw insertions. The findings of this study can be used to more systematically design visualization components of a navigation system.

Image-guided navigation for locally advanced primary and locally recurrent rectal cancer: Evaluation of its early cost-effectiveness.

e16015 Background: Radical resection is an important prognostic factor in patients with locally advanced primary (LARC) and locally recurrent rectal cancer (LRRC), but achieving this can be challenging. Therefore, an intraoperative surgical navigation system has been developed, showing improved radical resection rates for LARC and LRRC. This study evaluates the early cost-effectiveness of navigated surgery in LARC and LRRC compared to standard surgery. Methods: Two Markov decision models; one for each indication, were used to estimate the expected costs and outcomes for navigated and standard surgery from a Dutch healthcare perspective over a 3-year time horizon. The models started with a decision tree resulting in a radical or non-radical resection. Subsequently, the Markov-models comprised the health states “stable disease”, “progression” and “death”. The input parameters were based on prospective (navigation cohort n = 33) and retrospective (control group n = 142) data collected at the Netherlands Cancer Institute, reference and unit prices and expert opinion. Quality-Adjusted Life Years (QALYs) were measured by the EQ5D-5L. Additionally, a probabilistic sensitivity analysis and a scenario analysis were performed. Results: Navigated surgery showed incremental costs of €3139 and €2857 in LARC and LRRC, respectively. For LARC, for navigation and standard surgery we found: 2.54 vs 2.52 Life Years (LYs), and 2.06 vs 2.04 QALYs. For LRRC we found 2.17 vs 2.11 LYs and 1.73 vs 1.67 QALYs. The base case analysis showed an Incremental Cost-Effectiveness Ratio (ICER) of €144,192 for LARC and €51,802 for LRRC per QALY gained. At a willingness to pay threshold of €80,000, navigated surgery is not cost- effective in LARC but is cost-effective in LRRC. When a hospital lacks a hybrid OR and needs to invest in one to use the navigation system, which will increase the ICERs for both indications. Finally, more utilization of the navigation system (12% to 50% utilization rate) shows ICERs of € 65,257 and €20,648 for LARC and LRRC, respectively. Conclusions: Based on the current data, the navigation system is expected to be cost-effective in LRRC and has the potential to become cost-effective in LARC. To decrease the costs, it is crucial to identify more surgical indications for image-guided navigation. Especially as in the near future, image-guided surgery is expected to be a standard option in surgical practice. As these findings are sensitive to uncertainty in the data, a randomized controlled trial is advised to perform for relevant indications.

Value of 3D Preoperative Planning for Primary Total Hip Arthroplasty Based on Biplanar Weightbearing Radiographs

Two-dimensional (2D) planning on standard radiographs for total hip arthroplasty may not be sufficiently accurate to predict implant sizing or restore leg length and femoral offset, whereas 3D planning avoids magnification and projection errors. Furthermore, weightbearing measures are not available with computed tomography (CT) and leg length and offset are rarely checked postoperatively using any imaging modality. Navigation can usually achieve a surgical plan precisely, but the choice of that plan remains key, which is best guided by preoperative planning. The study objectives were therefore to (1) evaluate the accuracy of stem/cup size prediction using dedicated 3D planning software based on biplanar radiographic imaging under weightbearing and (2) compare the preplanned leg length and femoral offset with the postoperative result. This single-centre, single-surgeon prospective study consisted of a cohort of 33 patients operated on over 24 months. The routine clinical workflow consisted of preoperative biplanar weightbearing imaging, 3D surgical planning, navigated surgery to execute the plan, and postoperative biplanar imaging to verify the radiological outcomes in 3D weightbearing. 3D planning was performed with the dedicated hipEOS® planning software to determine stem and cup size and position, plus 3D anatomical and functional parameters, in particular variations in leg length and femoral offset. Component size planning accuracy was 94% (31/33) within one size for the femoral stem and 100% (33/33) within one size for the acetabular cup. There were no significant differences between planned versus implanted femoral stem size or planned versus measured changes in leg length or offset. Cup size did differ significantly, tending towards implanting one size larger when there was a difference. Biplanar radiographs plus hipEOS planning software showed good reliability for predicting implant size, leg length, and femoral offset and postoperatively provided a check on the navigated surgery. Compared to previous studies, the predictive results were better than 2D planning on conventional radiography and equal to 3D planning on CT images, with lower radiation dose, and in the weightbearing position.

PATIENT REGISTRATION USING PHOTOGRAMMETRIC SURFACE RECONSTRUCTION FROM SMARTPHONE IMAGERY

In navigated surgery the patient’s body has to be co-registered with presurgically acquired 3D data in order to enable navigation of the surgical instrument. For this purpose the body surface of the patient can be acquired by means of photogrammetry and co-registered to corresponding surfaces in the presurgical data. In this paper this task is exemplarily solved for 3D data of human heads using the face surface to establish correspondence. We focus on investigation of achieved geometric accuracies reporting positioning errors in the range of 1 mm.

PATIENT REGISTRATION USING PHOTOGRAMMETRIC SURFACE RECONSTRUCTION FROM SMARTPHONE IMAGERY

In navigated surgery the patient’s body has to be co-registered with presurgically acquired 3D data in order to enable navigation of the surgical instrument. For this purpose the body surface of the patient can be acquired by means of photogrammetry and co-registered to corresponding surfaces in the presurgical data. In this paper this task is exemplarily solved for 3D data of human heads using the face surface to establish correspondence. We focus on investigation of achieved geometric accuracies reporting positioning errors in the range of 1 mm.