Evaluation of a fluoroscopy-based navigation system enabling a virtual radiation-free preview of X-ray images for placement of cannulated hip screws. A cadaver study

Comparison of freehand technique and a novel laser-guiding navigation system in femoral neck-cannulated screw fixation: a randomized controlled trial

Cannulated screw fixation is essential in treating femoral neck fractures, and the widely used freehand technique has several limitations. Therefore, we designed a new laser-positioning and navigation system and compared its efficacy with that of the traditional freehand technique in the cannulated screw fixation of femoral neck fractures. This randomized controlled single-blind trial recruited patients with femoral neck fracture, who were treated using either the newly designed laser-navigation device or the freehand technique. In in-vitro experiments, using the femoral neck model, the laser group was better than the freehand group in terms of operation time (P = 0.0153) and radiation exposure time (P < 0.001). In in-vivo experiments, involving 30 patients (15 in each group), the laser group was better than the freehand group in terms of operation time (P < 0.001), radiation exposure time (P < 0.001), blood loss (P < 0.001) and first success rate (P = 0.03). There was no difference in visual analog scale score, Harris score, and fracture-healing time between the two groups. In conclusion, the novel laser-guiding navigation system resulted in shorter operation time, less radiation exposure, and higher first success rate compared with the freehand technique. Further qualified investigations with a larger number of patients and longer follow-up are required in the future.

Orientated-quantitative computed tomography study on individualized axial safety target area of femoral neck screw channel and establishment of a stable spatial coordinate system based on anterior cortex of femoral neck basilar

BACKGROUND

Frequent in-out-in femoral neck screws were reported potential huge iatrogenic-injury risks, related to axial safe target area (ASTA) of femoral neck screws channel. However, orientated-quantitative ASTA based on stable coordinate system was unreported before.

METHODS

Three-dimensional reconstruction was performed on computed tomography (CT) images of 139 intact normal hips, and the intersection area, defined as ASTA, was obtained by superimposing the axial CT images of each femoral neck. Taking anterior cortex of femoral neck basilar (AC-FNB) as landmark, a coordinate system was established to measure the anterior-posterior diameter (D-AP), the superior-inferior diameter (D-SI) and the oblique angle respectively. Each intersection was overlaid up to the axial CT images to determine the coronal location of the ASTA boundaries.

RESULTS

Each ASTA presented an inclined rounded triangle with a flat anterior base coincided with AC-FNB. There were significant sex differences in D-SI (male: 33.6±2.3 vs. female: 29.4±1.9 mm) and D-AP (male: 25.3±2.1 vs. 21.9±1.9 mm), P <0.001. D-SI was found to be positively correlated with D-AP ( R2 =0.6). All fluoroscopic visible border isthmus completely matched the corresponding ASTA boundaries. The oblique angle was 5-53° (male: 28.1±10.3°, female: 27.1±8.2°) without significant difference between sexes.

CONCLUSION

The intersection method was employed to conveniently acquire orientated-quantitative individualized ASTA. Under this coordinate system, x-ray data of screws could be converted to axial coordinates in CT ASTA, which could help surgeons design combined screws configuration preoperatively and evaluate quantitatively their axial position intraoperatively.

A new posterosuperior screw placement strategy to avoid in-out-in screws in femoral neck ractures

Objective

The inverted triangle configuration of the three cannulated screws is the classic fixation method most commonly performed for undisplaced femoral neck fractures in young and geriatric patients. However, the posterosuperior screw has a high incidence of cortical breach, known as an in-out-in (IOI) screw. In this study, we present a novel posterosuperior screw placement strategy to prevent the screw from becoming IOI.

Methods

Using computed tomography data and image-processing software, 91 undisplaced femoral neck fractures were reconstructed. The anteroposterior (AP), lateral, and axial radiographs were simulated. To simulate the intraoperative screw placement process, participants used three screw insertion angles (0°, 10°, and 20°) to place the screw on the AP and lateral views of the radiograph according to the three established strategies. On the AP radiograph, a screw was placed abutting (strategy 1), 3.25 mm away from (strategy 2), or 6.5 mm away from (strategy 3) the superior border of the femoral neck. On the lateral radiograph, all the screws were placed abutting the posterior border of the femoral neck. Axial radiographs were used to evaluate the screw position.

Results

In strategy 1, all the placed screws were IOI regardless of the screw insertion angle. In strategy 2, 48.3% (44/91) of IOI screws occurred at a 0° screw insertion angle, 41.7% (38/91) of IOI screws occurred at a 10° screw insertion angle, and 42.9% (39/91) of IOI screws occurred at a 20° screw insertion angle situation. In strategy 3, no IOI screw occurred, and the screw insertion angles did not affect the safety and accuracy of screw placement.

Conclusions

Screws placed according to strategy 3 are safe. The reliability of this screw placement strategy is unaffected by a screw insertion angle of less than 20 degrees.

The effect of artificial X-rays on C-arm positioning performance in a simulated orthopaedic surgical setting

PURPOSE

We designed an Artificial X-ray Imaging System (AXIS) that generates simulated fluoroscopic X-ray images on the fly and assessed its utility in improving C-arm positioning performance by C-arm users with little or no C-arm experience.

METHODS

The AXIS system was comprised of an optical tracking system to monitor C-arm movement, a manikin, a reference CT volume registered to the manikin, and a Digitally Reconstructed Radiograph algorithm to generate live simulated fluoroscopic images. A user study was conducted with 30 participants who had little or no C-arm experience. Each participant carried out four tasks using a real C-arm: an introduction session, an AXIS-guided set of pelvic imaging tasks, a non-AXIS guided set of pelvic imaging tasks, and a questionnaire. For each imaging task, the participant replicated a set of three target X-ray images by taking real radiographs of a manikin with a C-arm. The number of X-rays required, task time, and C-arm positioning accuracy were recorded.

RESULTS

We found a significant 53% decrease in the number of X-rays used and a moderate 10-26% improvement in lateral C-arm axis positioning accuracy without requiring more time to complete the tasks when the participants were guided by artificial X-rays. The questionnaires showed that the participants felt significantly more confident in their C-arm positioning ability when they were guided by AXIS. They rated the usefulness of AXIS as very good to excellent, and the realism and accuracy of AXIS as good to very good.

CONCLUSION

Novice users working with a C-arm machine supplemented with the ability to generate simulated X-ray images could successfully accomplish positioning tasks in a simulated surgical setting using markedly fewer X-ray images than when unassisted. In future work, we plan to determine whether such a system can produce similar results in the live operating room without lengthening surgical procedures.

A novel surgical navigation technology for placement of implants in slipped capital femoral epiphysis

BACKGROUND

Fixation with a single screw is the recommended treatment for slipped capital femoral epiphysis (SCFE). Achieving optimal implant positioning can be difficult owing to the complex geometry of the proximal femur in SCFE. We assessed a novel navigation technology incorporating an inertial measurement unit to facilitate implant placement in an SCFE model.

METHODS

Guidewires were placed into 30 SCFE models, using a navigation system that displayed the surgeon's projected implant trajectory simultaneously in multiple planes. The accuracy and the precision of the system were assessed as was the time to perform the procedure.

RESULTS

Implants were placed an average of 5.3 mm from the femoral head center, with a system precision of 0.94 mm. The actual trajectory of the implant deviated from the planned trajectory by an average of 4.9° ± 2.2°. The total average procedure time was 97 seconds.

CONCLUSION

The use of computer-based navigation in a SCFE model demonstrated good accuracy and precision in terms of both implant trajectory and placement in the center of the femoral head.

Evaluation of the new C-arm guiding system ClearGuide® in an orthopaedic and trauma operating theatre

BACKGROUND

The objective was to evaluate whether the new intraoperative C-arm guiding system ClearGuide® (CG) reduces radiation exposure of the staff in an Orthopaedic and Trauma operation theatre.

METHODS

Data of 95 patients CG was used were retrospectively compared using matched-pair analysis with controls without CG. Radiation dose (RD), fluoroscopic time (FT) and operation time (OT) were analysed in ten types of operative procedures.

RESULTS

Use of CG led to a significant reduction (p ≤ 0.05) of the RD in intramedullary nailing and plate fixation of femoral shaft fractures as well as plating of tibia shaft fractures. Concerning FT, use of CG led to a significant reduction (p ≤ 0.05) while performing kyphoplasties and plate fixation of femoral shaft fractures. Regarding OT, no statistical significance was observed.

CONCLUSIONS

CG as a simple, reproducible and intuitive communication tool for C-arm guidance reduces intraoperative staff radiation exposure especially while fixation of long bone fractures and in spine surgery.

A Novel Guidewire Aiming Device to Improve the Accuracy of Guidewire Insertion in Femoral Neck Fracture Surgery Using Cannulated Screw Fixation

Background

The aim of this study was to improve the accuracy of guidewire insertion in the femoral neck fracture surgery using cannulated screw fixation.

Material/Methods

A novel aiming device was designed and manufactured. Between January 2010 and June 2012, 64 femoral neck fracture patients were included into the study. All 64 patients were divided into 2 groups randomly. The aiming device was used during the operation for patients in the experimental group, but not in the control group.

Results

There were no statistically significant differences in operative time or bleed volume between the groups (P>0.05). The frequency of guidewire drilling was significantly lower in the experimental group than in the control group (P<0.05). The angle between the first cannulated screw and the central axis of the femoral neck in coronal plane and sagittal plane, and the distance between the bottom cannulated screw and the medial calcar femorale rim, were significantly smaller in the experimental group than in the control group (P<0.05).

Conclusions

The aiming device is simple in structure and easy to use. It could help surgeons to accurately insert cannulated screw guidewires. The aiming device is suitable for broad clinical use.

Three-dimensional computer-assisted navigation for the placement of cannulated hip screws. A pilot study

PURPOSE

Medial femoral neck fractures are common, and closed reduction and internal fixation by three cannulated screws is an accepted method for the surgical treatment. Computer navigation for screw placement may reduce fluoroscopy time, the number of guidewire passes and optimise screw placement.

METHODS

In the context of a sawbone study, a computer-assisted planning and navigation system based on 3D-imaging for guidewire placement in the femoral neck was tested to improve screw placement. Three screws were inserted into 12, intact, femoral sawbones using the conventional technique and into 12, intact, femoral sawbones guided by the computer-based navigation system. Guidewire and subsequent screw placement in the femoral neck were evaluated.

RESULTS

Use of the navigation system resulted in a significant reduction of the number of drilling attempts (p≤0.05) and achieved optimised accuracy of implant placement by attaining significantly better screw parallelism (p≤0.05) and significantly enlarged neck-width coverage by the three screws (p≤0.0001). Computer assistance significantly increased the number of fluoroscopic images (p≤0.001) and the operation time (p≤0.0001).

CONCLUSIONS

Three-dimensional computer-assisted navigation improves accuracy of cannulated screw placement in femoral neck while increasing the number of fluoroscopic images and operation time. Additional studies including fractured sawbones and cadaver models with the goal of reducing operation time are indispensable before introduction of this navigation system into clinical practice.