Three-dimensional-printed patient-specific instrumentation is an accurate tool to reproduce femoral bone tunnels in multiple-ligament knee injuries.

PURPOSE: Multiple-ligament knee reconstruction techniques often involve the creation of several bone tunnels for various reconstruction grafts. A critical step in this procedure is to avoid short tunnels or convergences among them. Currently, no specific template guide to reproduce these angulations has been reported in the literature, and the success of the technique still depends on the experience of the surgeon. The aim of this study is to analyze the accuracy and reliability of 3D-printed patient-specific instrumentation (PSI) for lateral and medial anatomical knee reconstructions. METHODS: Ten cadaveric knees were scanned by computed tomography (CT). Using specific computer software, anatomical femoral attachments were identified: (1) on the lateral side the lateral collateral ligament (LCL) and the popliteal tendon (PT) and (2) on the medial side the medial collateral ligament (MCL) and the posterior oblique ligament (POL). Four bone tunnels were planned for each knee, and PSI with different directions were designed as templates to reproduce the planned tunnels during surgery. Twenty 3D-printed PSI were used: ten were tailored to the medial side for reconstructing MCL and POL tunnels, and the other ten were tailored to the lateral side for reconstructing LCL and PT tunnels. Postoperative CT scans were made for each cadaveric knee. The accuracy of the use of 3D-printed PSI was assessed by superimposing post-operative CT images onto pre-operative images and analyzing the deviation of tunnels performed based on the planning, specifically the entry point and the angular deviations. RESULTS: The median entry point deviations for the tunnels were as follows: LCL tunnel, 1.88 mm (interquartile range (IQR) 2.2 mm); PT tunnel, 2.93 mm (IQR 1.17 mm); MCL tunnel, 1.93 mm (IQR 4.26 mm); and POL tunnel, 2.16 mm (IQR 2.39). The median angular deviations for the tunnels were as follows: LCL tunnel, 2.42° (IQR 6.49°); PT tunnel, 4.15° (IQR 6.68); MCL tunnel, 4.50° (IQR 6.34°); and POL tunnel, 4.69° (IQR 3.1°). No statistically significant differences were found in either the entry point or the angular deviation among the different bone tunnels. CONCLUSION: The use of 3D-printed PSI for lateral and medial anatomical knee reconstructions provides accurate and reproducible results and may be a promising tool for use in clinical practice.

High-power short-duration vs. standard radiofrequency cardiac ablation: comparative study based on an in-silico model.

PURPOSE: While the standard setting during radiofrequency catheter ablation (RFCA) consists of applying low power for long times, a new setting based on high power and short duration (HPSD) has recently been suggested as safer and more effective. Our aim was to compare the electrical and thermal performance of standard vs. HPSD settings, especially to assess the effect of the catheter orientation. METHODS: A 3D computational model was built based on a coupled electric-thermal-flow problem. Standard (20 W-45 s and 30 W-30 s) and HPSD settings (70 W-7 s and 90 W-4 s) were compared. Since the model only included a cardiac tissue fragment, the power values were adjusted to 80% of the clinical values (15, 23, 53 and 69 W). Three catheter-tissue orientations were considered (90°, 45° and 0°). Thermal lesions were assessed by the Arrhenius equation. Safety was assessed by checking the occurrence of steam pops (100 °C in tissue) and thrombus formation (80 °C in blood). RESULTS: The computed thermal lesions were in close agreement with the experimental data in the literature, in particular with in vivo studies. HPSD created shallower and wider lesions than standard settings, especially with the catheter at 45°. Steam pops occurred earlier with HPSD, regardless of catheter orientation. CONCLUSION: HPSD seems to be more effective in cases that need shallow and extensive lesions, especially when the catheter is at 0° or at 45°, as used in pulmonary vein isolation.

3D printing innovation: New insights into upper extremity surgery planning.

INTRODUCTION: Surgical planning relies on the use of images to develop an action plan prior to the actual surgical intervention. Imaging technology improvement together with the development of specific software to treat three dimensional images has increased the accuracy and capabilities of pre-surgical planning. In addition to this, 3D printing allows us to manufacture customized surgical tools to implement and aid in the success of surgeries. MATERIAL AND METHODS: 3D virtual planning together with 3D printing has been implemented through different approaches in 8 different upper extremity trauma cases. We describe these 8 cases (2 women and 6 men with ages ranging from 16 to 67 years), their specific challenges and management. RESULTS: We show how 3D technology changes the conception, planning and execution of surgery in 8 different cases. In addition, we describe what challenges were faced as well as the various utilities of 3D technology beyond that of anatomical model printing. CONCLUSIONS: The use of 3D technology has improved and enhanced surgical planning. It allows us to view and virtually manipulate fracture fragments prior to surgery. It also enables us to develop customized surgical tools and guides that can increase the accuracy of certain procedures, and help in the management of orthopaedic and trauma lesions. We believe that the use of this technology is beneficial to both the patient and surgeon, since it reduces surgical time and complications giving a better understanding of the injury and its treatment.