Free-hand Procedure Research Articles

Guided versus freehand single implant placement: A 3-year parallel randomized clinical trial

ObjectivesThe present parallel randomized clinical trial aimed to assess, after a 3-year follow-up period, whether the choice of surgical technique—either manual or guided—and of the operator - non-expert operator or skilled - can affect the stability of peri‑implant marginal bone levels in implants placed 1 mm sub-crestal. Materials and methodsPatients received platform-switched implants (Anyridge, MegaGen Implant Co., Gyeongbuk, South Korea) featuring a 5-degree internal conical connection and supporting single screw-retained fixed crowns. The implants were randomly assigned to be placed through a digitally static guided surgery procedure (Test group - GS) or a freehand surgical technique (Control Group - FH). A non-expert operator (fewer than 20 implants placed in his professional activity) was selected to perform procedures for the GS Group, while a skilled operator (with over 1000 implants placed in his professional activity) was chosen for the FH Group. Marginal bone level (MBL) was measured at prosthesis installation (t0) and at 1 (t1), 2 (t2) and 3 years (t3) of follow-up. Changes in MBL from t0 to t3 were analyzed through periapical radiographs. Moreover, MBL changes at all time points were correlated to different supra-crestal soft tissue heights (STH): less than 3 and ≥ 3 mm, respectively. Results60 implants in 18 patients were examined, with 30 implants allocated to the GS group and 30 to the FH group. The difference in MBL change between the two groups was 0.11 ± 0.22 mm, which was not statistically significant (p = 0.61). At the time of prosthetic loading, the mean MBL for implants with STH less than 3 mm was 0.33 mm higher than implants with STH ≥ 3 mm, though this difference was not statistically significant (P = 0.065). ConclusionsDigitally static guided implant placement, performed by a non-expert operator, does not limit marginal bone remodeling, when compared to a freehand procedure performed by an experienced operator. Clinical significanceAfter correct and careful planning, early marginal bone levels (MBL) around conical connection, platform-switched implants placed sub-crestally may be stable in time. Digital planning and surgery have the potential to assist non-expert clinicians in achieving implant placements with comparable outcomes to those performed by experts.

Piezoelectric Device and Dynamic Navigation System Integration for Bone Window-Guided Surgery

IntroductionThis study investigates the feasibility of integrating a piezoelectric device (PIEZO) into a dynamic navigation system (DNS) for bone-window guided surgery. It compares the accuracy and efficiency of PIEZO + DNS to PIEZO + Freehand (FH) procedure for bone-window cutting and root-end resection (RER). MethodsForty-eight mandibular molars of 3D-printed surgical jaw models were divided into two groups: PIEZO + DNS (n = 24) and PIEZO + FH (n = 24). Cone-beam computed tomography scans were taken before and after the procedure. The procedure was virtually planned on X-guide software. The bone-window cutting and RER were conducted with a PIEZO under dynamic navigation in the PIEZO + DNS group and using the dental operating microscope in the PIEZO + FH group. The 2D- and 3D-accuracy deviations and angular deflection were measured for the bone window cut. The root length resected and resection angle were calculated. The bone window cut, RER, total operating time, and number of mishaps were recorded. ResultsPIEZO + DNS was more accurate than PIEZO + FH for bone-window cutting, showing fewer 2D and 3D deviations and less angular deflection (P < .05). The resection angle was lower in the PIEZO + DNS (P < .05). The bone-window cut and total operating time were significantly reduced using a DNS (P < .05). There was no difference in the number of mishaps (P > .05). ConclusionsWithin the limitations of this in vitro study, the integration of a PIEZO into a DNS is feasible for bone-window guided surgery. The DNS improved the accuracy and efficiency of bone-window cutting.

Performances of novel custom 3D-printed cutting guide in canine caudal maxillectomy: a cadaveric study.

Caudal maxillectomies are challenging procedures for most veterinary surgeons. Custom guides may allow the procedure to become more accessible. A cadaveric study was performed to evaluate the accuracy and efficiency of stereolithography guided (3D-printed) caudal maxillectomy. Mean absolute linear deviation from planned to performed cuts and mean procedure duration were compared pairwise between three study groups, with 10 canine cadaver head sides per group: 3D-printed guided caudal maxillectomy performed by an experienced surgeon (ESG) and a novice surgery resident (NSG), and freehand procedure performed by an experienced surgeon (ESF). Accuracy was systematically higher for ESG versus ESF, and statistically significant for 4 of 5 osteotomies (p < 0.05). There was no statistical difference in accuracy between ESG and NSG. The highest absolute mean linear deviation for ESG was <2 mm and >5 mm for ESF. Procedure duration was statistically significantly longer for ESG than ESF (p < 0.001), and for NSG than ESG (p < 0.001). Surgical accuracy of canine caudal maxillectomy was improved with the use of our novel custom cutting guide, despite a longer duration procedure. Improved accuracy obtained with the use of the custom cutting guide could prove beneficial in achieving complete oncologic margins. The time increase might be acceptable if hemorrhage can be adequately controlled in vivo. Further development in custom guides may improve the overall efficacy of the procedure.

Preparing guiding planes for removable partial dentures: an in vitro comparison between assisted CAD-CAM template procedure and freehand preparation

ObjectivesTo compare the trueness of computer-aided design and computer-aided manufacturing (CAD-CAM) assisted procedure and freehand procedure for preparing guiding planes for removable partial dentures (RPDs). MethodsForty identical mandibular resin casts were divided into two groups in which the guiding planes of two abutment teeth were prepared freehand (control group, n = 20) and using rigidly constrained templates (test group, n = 20). The template was designed on a digital cast of virtually prepared guiding planes and fabricated by selective laser melting using cobalt-chromium alloy. To assess the 3D trueness, all prepared guiding planes (Test data) were digitized using a laboratory scanner and compared to the virtually designed guiding planes (Reference data). The angle deviation between the Test data and the designed direction of the path of placement was measured for assessing the direction trueness of guiding plane preparation. ResultsThe 3D trueness of guiding plane preparation was significantly better in the Test group (48.4 ± 12.9 μm) than in the Control group (128.5 ± 37.6 μm, p < 0.01). The direction trueness of guiding plane preparation was also significantly better in the Test group (1.20 ± 0.55°) than in the Control group (7.68 ± 3.00°, p < 0.01). ConclusionsThe CAD-CAM template assisted procedure can significantly improve tooth preparation of the guiding planes compared to the freehand preparation. The CAD-CAM template could help clinicians prepare parallel guiding planes in a predictable manner.

Ideal trajectory for frontal ventriculostomy: Radiological study and anatomical study

ObjectiveSeveral techniques have been described to improve the accuracy of the freehand procedure for frontal ventriculostomy and reduce complications due to suboptimal placement or misplacement of the catheter tip. To date, none of the available studies have found a reliable, low cost and consistent technique. We aimed to provide a standardized protocol for freehand frontal ventriculostomy. MethodsIn the first part of the radiological study, 125 CT scans were used to measure the length of the catheter using 2 right-sided entry points. In the second part, a grid of 24 entry points on the frontal bone was used in 50 CT scans to record the distance from the cranial surface to the Foramen of Monro (FM). Ventriculostomy was performed on six cadaveric heads using a grid of 9 entry points, comparing a 5 ml syringe with the freehand technique to reach the target. ResultsThe first part of the radiological study showed a length from the cranial surface to the FM was overall 67,38 ± 1,03 mm. For the second part, the mean length of the 24 selected points was 68,54 ± 2,73 mm without statistical difference. In the anatomical study, the FM was reached 8 times (14.8%) with the syringe vs 31 times (57.4%) with the freehand technique, and the ventricles 43 (79.6%) vs 37 (68.5%). The mean lengths from the skull to the FM were 71.33 ± 4.21 mm. ConclusionsIn this study, we showed the optimal length of a frontal ventricular catheter. We have also demonstrated that the portion of the frontal bone above the superior temporal lines matches a sphere in which the center is the FM.

Autonomous Spinal Robotic System for Transforaminal Lumbar Epidural Injections: A Proof of Concept of Study.

Phantom study. The aim of our study is to demonstrate in a proof-of-concept model whether the use of a marker less autonomous robotic controlled injection delivery system will increase accuracy in the lumbar spine. Ideal transforaminal epidural injection trajectories (bilateral L2/3, L3/4, L4/5, L5/S1 and S1) were planned out on a virtual pre-operative planning software by 1 experienced provider. Twenty transforaminal epidural injections were administered in a lumbar spine phantom model, 10 using a freehand procedure, and 10 using a marker less autonomous spinal robotic system. Procedural accuracy, defined as the difference between pre-operative planning and actual post-operative needle tip distance (mm) and angular orientation (degrees), were assessed between the freehand and robotic procedures. Procedural accuracy for robotically placed transforaminal epidural injections was significantly higher with the difference in pre- and post-operative needle tip distance being 20.1 (±5.0) mm in the freehand procedure and 11.4 (±3.9) mm in the robotically placed procedure (P < .001). Needle tip precision for the freehand technique was 15.6mm (26.3 - 10.7) compared to 10.1mm (16.3 - 6.1) for the robotic technique. Differences in needle angular orientation deviation were 5.6 (±3.3) degrees in the robotically placed procedure and 12.0 (±4.8) degrees in the freehand procedure (P = .003). The robotic system allowed for comparable placement of transforaminal epidural injections as a freehand technique by an experienced provider, with additional benefits of improved accuracy and precision.

Efficacy of Shadow-Based Needle Positioning System in Performing CT Image-Guided Percutaneous Biopsy of Lung Lesions: Our Initial Experience.

Context Computerized tomography (CT) is widely used for various interventions and there is a need for an effective navigation tool, for best outcomes. Aim The study was performed to evaluate the efficacy of light- and shadow-based needle positioning assistance device, an innovative navigation tool over the conventional freehand technique, in performing CT image-guided percutaneous interventions. Settings and Design This randomized control trial was performed among patients undergoing CT-guided percutaneous intervention for lung pathologies. Methodology A total of 60 participants were randomized into an intervention group and a control group. The accuracy of needle insertion and other efficacy parameters were assessed for both groups. Post needle placement, CT images were used to evaluate the study endpoints. Statistical Analysis Statistical analysis was performed using SPSS ver. 20 software. Results The mean needle positioning accuracy was 2.1 mm in the experimental group compared with 7.2 mm in the control group freehand procedures. The average time to position the needle at the desired target location was 2.5 minutes in the assisted procedure as compared with 5.3 minutes in the freehand procedure ( p < 0.05). The total number of check scans required to position the needle was 1.3 for assisted procedures and 1.9 for freehand procedures. Conclusion The use of shadow-based assistance device for CT-guided interventions is proven to be efficient and safer with high needle positioning accuracy.

Comparison between freehand technique and computed tomography-based navigation in acetabular cup placement through direct anterior approach for total hip arthroplasty.

In total hip arthroplasty (THA), improper cup orientation can result in dislocation, early excessive polyethylene wear, and pain following THA. The supine position during THA provides a more reproducible functional pelvic position than the lateral decubitus position and may allow freehand cup placement as reliable as that obtained by computer navigation. The purpose of this study was to investigate the accuracy of freehand cup placement through a supine direct anterior approach (DAA) compared with computed tomography (CT)-based navigation. The same surgeon performed primary cementless THA through the DAA in 144 supine patients. Seventy-two patients underwent freehand cup placement with standard mechanical guidance-oriented radiographic target cup positioning, and 72 underwent placement with CT-based navigation guidance. Using three-dimensional templating software, the study group calculated cup inclination and anteversion on postoperative CT scans. The navigation method resulted in a significantly smaller deviation of inclination from the target (p < 0.05); the difference in anteversion was not significant. In addition, the navigation method resulted in significantly fewer cups placed ± 10° outside the target position (0% for inclination, 0% for anteversion) than did the freehand procedure (26% for inclination, 25% for anteversion) (p < 0.0001). Freehand cup placement is less reliable even in the supine position. Use of a CT-based navigation system can significantly improve cup positioning in THA through the DAA by reducing the incidence of outliers.

Augmented reality-assisted ventriculostomy.

Placement of a ventricular drain is one of the most common neurosurgical procedures. However, a higher rate of successful placements with this freehand procedure is desirable. The authors' objective was to develop a compact navigational augmented reality (AR)-based tool that does not require rigid patient head fixation, to support the surgeon during the operation. Segmentation and tracking algorithms were developed. A commercially available Microsoft HoloLens AR headset in conjunction with Vuforia marker-based tracking was used to provide guidance for ventriculostomy in a custom-made 3D-printed head model. Eleven surgeons conducted a series of tests to place a total of 110 external ventricular drains under holographic guidance. The HoloLens was the sole active component; no rigid head fixation was necessary. CT was used to obtain puncture results and quantify success rates as well as precision of the suggested setup. In the proposed setup, the system worked reliably and performed well. The reported application showed an overall ventriculostomy success rate of 68.2%. The offset from the reference trajectory as displayed in the hologram was 5.2 ± 2.6 mm (mean ± standard deviation). A subgroup conducted a second series of punctures in which results and precision improved significantly. For most participants it was their first encounter with AR headset technology and the overall feedback was positive. To the authors' knowledge, this is the first report on marker-based, AR-guided ventriculostomy. The results from this first application are encouraging. The authors would expect good acceptance of this compact navigation device in a supposed clinical implementation and assume a steep learning curve in the application of this technique. To achieve this translation, further development of the marker system and implementation of the new hardware generation are planned. Further testing to address visuospatial issues is needed prior to application in humans.

MRI-guided lumbar spinal injections with body-mounted robotic system: cadaver studies

Introduction This paper reports the system integration and cadaveric assessment of a body-mounted robotic system for MRI-guided lumbar spine injections. The system is developed to enable MR-guided interventions in closed bore magnet and avoid problems due to patient movement during cannula guidance. Material and methods The robot is comprised by a lightweight and compact structure so that it can be mounted directly onto the lower back of a patient using straps. Therefore, it can minimize the influence of patient movement by moving with the patient. The MR-Conditional robot is integrated with an image-guided surgical planning workstation. A dedicated clinical workflow is created for the robot-assisted procedure to improve the conventional freehand MRI-guided procedure. Results Cadaver studies were performed with both freehand and robot-assisted approaches to validate the feasibility of the clinical workflow and to assess the positioning accuracy of the robotic system. The experiment results demonstrate that the root mean square (RMS) error of the target position to be 2.57 ± 1.09 mm and of the insertion angle to be 2.17 ± 0.89°. Conclusion The robot-assisted approach is able to provide more accurate and reproducible cannula placements than the freehand procedure, as well as to reduce the number of insertion attempts.

Accuracy Assessment of Freehand Pedicular Screw Placement.

The purpose of this prospective study was to determine the accuracy of pedicular screw insertion without the use of fluoroscopy. This study was conducted on patients with spinal diseases in need of pedicular screw fixation and fusion. The included patients suffered from such conditions as vertebral fracture, spinal stenosis, kyphosis, tumor, and pelvic fractures and were managed with triangular osteosynthesis fixation. However, those with scoliosis deformity were excluded from the study. A total of 760 pedicular screws were inserted in C7 to S1 vertebrae without using fluoroscopy. The locations of the screws were assessed by means of computed tomography scan after the surgery. The data were analyzed in SPSS software (version 22) using the Chi-square test. Out of 387 thoracic screws and 373 lumbar screws, 65 (16.8%) and 34 (9.1%) screws perforated the pedicle wall or vertebral body, respectively. The most frequent locations of perforation in the thoracic and lumbar spine were the anterior cortex of the vertebral body and medial wall of the pedicle, respectively. Except for the perforation of the anterior vertebral body (P=0.0001), there was no difference between the left and right sides or between thoracic and lumbar sites in terms of the preformation of the screw. No complication was observed due to screw perforation. Our findings revealed the unnecessity of using fluoroscopy in spine surgeries for the insertion of pediculate screws. In this regard, the use of fluoroscopy for the placement of pedicular screw resulted in similar accuracy and complications, as compared to the free hand procedure.

Presentation and short-term evaluation of an all-in-one patient-specific implant for cranial reconstruction: A randomized controlled trial

Cranial reconstruction after bone graft harvesting remains a challenge. A patient-specific implant (PSI) to guide harvesting and reconstruction was evaluated and compared with the use of a free-hand procedure with calcium phosphate cement (C). Patients were randomized to either the PSI or C group. The outcome was measured clinically and radiographically as the primary endpoint. Secondary endpoints were ease of application, patient and surgeon satisfaction, and the complication rate. Twenty patients were randomized to the PSI (n=10) and C (n=10) groups. Two PSI patients were switched to the cement group due to a poor fit of the PSI. There was a non-significant trend towards more successful outcomes in the PSI group. Two PSI patients presented palpable screws, and one cement patient had a palpable dimple. Cone beam computed tomography showed a significantly lower median volume discrepancy in the PSI group (P<0.0001). The total surgical manipulation time was significantly higher in the PSI group. At 10 days postoperative, three PSI and two C patients presented with minor postoperative complications. There was no significant difference in patient or surgeon satisfaction. PSIs are a reliable alternative to cement. This PSI is novel as it also serves as a guide for harvesting the bone blocks required for reconstructive purposes.

Clinical results of the open ring PMMA guider assisted capsulorrhexis in cataract surgery

BackgroundTo compare the results of continuous curvilinear capsulorrhexis(CCC) after application of an open ring-shaped guider compared with a free-hand procedure in eyes with cataracts.MethodsThis study comprised patients undergoing cataract surgery in Seoul St.Mary’s Hospital, The Catholic University of Korea. Eyes were grouped depending on the capsulotomy method; CCC was performed by free-hand procedure on 94 eyes (free-hand group), and it was performed under the guidance after introduction of an open ring-shaped guider on consecutive 89 eyes (guided group). Horizontal and vertical diameter, area and circularity of capsulotomy were measured postoperatively at one day, two months and six months. Differences in parameters and the percentage of ideal capsulorrhexis were analyzed between the two groups.ResultsOn the first postoperative day, the vertical diameter in the guided group (5.24 ± 0.16 mm) was significantly longer than that of the free-hand group (5.01 ± 0.65 mm, P = 0.019). The area of capsulotomy was larger in the guided group (21.55 ± 0.87 mm2) than that of the free-hand group (20.34 ± 2.96 mm2, P < 0.001). Circularity in the guided group (0.84 ± 0.03), was significantly greater than that of the free-hand group (0.69 ± 0.17, P = 0.036). Ideal capsulorrhexis was obtained in 60 eyes (67%) in the free-hand group and 81 eyes (86%) in the guided group.ConclusionsAfter introduction of an open ring-shaped guider, CCC became larger and more circular with less anterior capsular contracture. The rate of acquiring ideal capsulorrhexis was higher in the guided group than it was in the free-hand group for six months after surgery.

Evaluation of a Robotic Assistance-System For Percutaneous Computed Tomography-Guided (CT-Guided) Facet Joint Injection: A Phantom Study.

BackgroundThe aim of this study was to compare robotic assisted and freehand facet joint puncture on a phantom model in regards to time requirements and puncture accuracy.Material/MethodsForty facet joints were punctured, 20 using a robotic guidance system and 20 using a freehand procedure. Side and height of the facet joints were randomized and identical for both groups. Procedural accuracy, defined as axial and sagittal deviation, as well as the number of corrections were assessed. Procedure times for each step were documented and time requirements for pre-positioning, reconstruction, planning, and total intervention were calculated.ResultsTotal procedure time for robotic guidance was 259±111 seconds versus 119±77 seconds for freehand procedure (p=1.0). Procedural accuracy for robotic guidance was significantly higher with 0 corrections versus 1.3 corrections for freehand procedure (p=0.02). Needle deviation in the robotics arm was 0.35±1.1 mm in the axial and 2.15±1.2 mm in the sagittal reconstruction.ConclusionsRobotic assisted puncture of the facet joint allowed accurate positioning of the needle with a lower number of needle readjustments. Higher procedural accuracy was marginally offset by a slightly longer intervention time.

A Retrospective Comparison of Implants in the Pterygomaxillary Region: Implant Placement with Two-Stage, Single-Stage, and Guided Surgery Protocols

Implants placed into the pterygomaxillary region allow for increased posterior support and a full complement of teeth without the need for distal cantilevers. With advancements in research and technology, implant delivery has evolved from the traditional two-stage procedure to immediate loading freehand and guided surgical template protocols. The purpose of this retrospective study is to determine if there is a significant difference in implant survival rates between these protocols. All pterygomaxillary implants placed in a single private practice from September 1985 to July 2011 were categorized into three separate classifications (two-stage freehand, single-stage freehand, or single-stage guided) by retrospective chart review. Life tables were constructed to determine the cumulative survival rates (CSR), and ANOVA was used to identify statistical significance. A total of 981 patients comprising 371 males and 610 females were included in the study. Of all pterygomaxillary implants, 1,460 of 1,608 implants osseointegrated for a CSR of 90.80%. Seven hundred nine of the 825 two-stage, 624 of the 647 single-stage, and 127 of the 136 guided surgery implants osseointegrated for CSRs of 85.94%, 96.45%, and 93.38%, respectively. The comparison between two-stage and single-stage protocols was statistically significant, (P < .05) while the difference between single-stage guided versus freehand protocols was found to be statistically insignificant (P > .05). The results from this retrospective study reinforce that immediate loading of pterygomaxillary implants with a provisional prosthesis is beneficial to both doctor and patient. The lower CSR for the guided surgery protocol compared with the single-stage freehand procedure is statistically insignificant, suggesting guided surgery is still a viable and recommended option for qualified patients.

A novel Laser Navigation System reduces radiation exposure and improves accuracy and workflow of CT-guided spinal interventions: A prospective, randomized, controlled, clinical trial in comparison to conventional freehand puncture

PurposePhantom model evaluation and prospective randomized clinical trial to assess the clinical feasibility and benefit of using a novel Laser Navigation System (LNS) in CT-guided epidural and perineural injections in comparison to the conventional freehand procedure. MethodsThe LNS guided puncture technique was compared to the standard CT-guided freehand treatment using a phantom model and a randomized clinical trial. Spinal injections were administered by an experienced interventional team to evaluate needle placement accuracy, treatment time and radiation exposure. ResultsIn the LNS group of the phantom model study, the needle entrance point accuracy of 0.5mm (freehand 3.1mm), needle target point accuracy of 2.0mm (freehand 3.5mm), number of control CT slices of 1.4 (freehand 2.7) and needle placement time of 5min 4s (freehand: 9min 18s) showed significant improvements compared to freehand in 60 punctures. In the clinical trial the LNS group achieved needle entrance point accuracy of 1.3mm (freehand 4.6mm), needle angulation accuracy of 0.4° (freehand 2.3°), number of control CT slices of 1.1 (freehand 1.8) and needle placement time of 6min 54s (freehand 9min 00s), showing significant improvements compared to freehand in a total of 58 CT-guided interventions. ConclusionThe LNS group showed significantly improved results in both study designs. Both the phantom model evaluation and the clinical trial of spinal injections showed feasibility and efficacy of using the novel LNS. Even an experienced interventional team worked with it more precise, faster and with reduced radiation exposure.

Computer-assisted planning and navigation improves cutting accuracy during simulated bone tumor surgery of the pelvis

Background: Resection of bone tumors within the pelvis requires good cutting accuracy to achieve satisfactory safe margins. Manually controlled bone cutting can result in serious errors, especially due to the complex three-dimensional geometry, limited visibility, and restricted working space of the pelvic bone. This experimental study investigated cutting accuracy during navigated and non-navigated simulated bone tumor cutting in the pelvis.Methods: A periacetabular tumor resection was simulated using a pelvic bone model. Twenty-three operators (10 senior and 13 junior surgeons) were asked to perform the tumor cutting, initially according to a freehand procedure and later with the aid of a navigation system. Before cutting, each operator used preoperative planning software to define four target planes around the tumor with a 10-mm desired safe margin. After cutting, the location and flatness of the cut planes were measured, as well as the achieved surgical margins and the time required for each cutting procedure.Results: The location of the cut planes with respect to the target planes was significantly improved by using the navigated cutting procedure, averaging 2.8 mm as compared to 11.2 mm for the freehand cutting procedure (p < 0.001). There was no intralesional tumor cutting when using the navigation system. The maximum difference between the achieved margins and the 10-mm desired safe margin was 6.5 mm with the navigated cutting process (compared to 13 mm with the freehand cutting process).Conclusions: Cutting accuracy during simulated bone cuts of the pelvis can be significantly improved by using a freehand process assisted by a navigation system. When fully validated with complementary in vivo studies, the planning and navigation-guided technologies that have been developed for the present study may improve bone cutting accuracy during pelvic tumor resection by providing clinically acceptable margins.

Strategic Placement of Bedside Ventriculostomies Using Ultrasound Image Guidance: Report of three Cases

The blind free-hand technique for external ventricular drain (EVD) placement sometimes requires multiple attempts, and catheter location is often less than ideal. Our institution has adapted an intraoperative ultrasound-guided ventriculostomy technique for the placement of EVDs at the bedside. Our experience with ultrasound at the bedside has proven to be invaluable in certain circumstances. We present three cases of strategic EVD catheter trajectories that were made possible at the bedside with the use of ultrasound. Illustrative cases were chosen from a larger prospective study investigating the ultrasound-guided EVD technique. A portable ultrasound with a "burr hole" probe was used with modification of the standard surgical technique for placement of EVDs at the bedside. Case 1 describes an unexpected re-hemorrhage that was first realized by the ultrasound image obtained during the bedside EVD placement procedure. The catheter was purposefully directed across midline to the more prominent ventricle on the contralateral side based on this real-time finding. Case 2 describes how ultrasound was used to salvage the failed free-hand procedure and cannulate an extremely small ventricular space at the bedside. Case 3 describes an unconventionally placed burr hole that provided a customized trajectory in which the EVD catheter was placed just laterally and inferior to a large frontal hematoma. Ultrasound-guided bedside EVD placement allows EVD trajectories to be customized based on real-time information to accommodate for distorted and dynamic anatomy of the brain and its ventricles.

Validation and Usefulness of a Computer-Assisted Cup-Positioning System in Total Hip Arthroplasty

Malpositioning of the acetabular component during total hip arthroplasty increases the risk of dislocation, reduces the range of motion, and can be responsible for early wear and loosening. The purpose of this study was to compare computer-assisted with freehand insertion of the acetabular component. A randomized, controlled, matched prospective study of two groups of thirty patients each was performed. In the first group, cup positioning was assisted by an imageless computer-assisted surgical system based on bone morphing. In the control group, the cup was placed freehand. All of the patients were operated on by the same surgeon through an anterolateral approach. Cup anteversion and abduction angles were measured on three-dimensional computed tomography reconstructions postoperatively for each patient by an independent observer using special cup-evaluation software. There were sixteen men and fourteen women in each group, and the mean body-mass index was approximately 25 in each group. The computer-assisted procedure took a mean of twelve minutes longer than the freehand procedure. Fifty-seven percent (seventeen) of the thirty cups placed freehand and 20% (six) of the thirty in the computer-assisted group were outside of the defined safe zone (outliers). This difference was significant (p = 0.002). There were no differences between the computer-assisted group and the freehand-placement group with regard to the mean abduction and anteversion angles, but there was a significant heterogeneity of variances, with the lowest variations in the computer-assisted group. Use of an imageless navigation system can improve cup positioning in total hip arthroplasty by reducing the percentage of outliers.

Validation and Usefulness of a Computer-Assisted Cup-Positioning System in Total Hip Arthroplasty

Background: Malpositioning of the acetabular component during total hip arthroplasty increases the risk of dislocation, reduces the range of motion, and can be responsible for early wear and loosening. The purpose of this study was to compare computer-assisted with freehand insertion of the acetabular component. Methods: A randomized, controlled, matched prospective study of two groups of thirty patients each was performed. In the first group, cup positioning was assisted by an imageless computer-assisted surgical system based on bone morphing. In the control group, the cup was placed freehand. All of the patients were operated on by the same surgeon through an anterolateral approach. Cup anteversion and abduction angles were measured on three-dimensional computed tomography reconstructions postoperatively for each patient by an independent observer using special cup-evaluation software. Results: There were sixteen men and fourteen women in each group, and the mean body-mass index was approximately 25 in each group. The computer-assisted procedure took a mean of twelve minutes longer than the freehand procedure. Fifty-seven percent (seventeen) of the thirty cups placed freehand and 20% (six) of the thirty in the computer-assisted group were outside of the defined safe zone (outliers). This difference was significant (p = 0.002). There were no differences between the computer-assisted group and the freehand-placement group with regard to the mean abduction and anteversion angles, but there was a significant heterogeneity of variances, with the lowest variations in the computer-assisted group. Conclusions: Use of an imageless navigation system can improve cup positioning in total hip arthroplasty by reducing the percentage of outliers. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.