[A new parallel drill guide for navigating femoral neck screw placement. Development and evaluation]

Computer-Assisted Orthopedic and Trauma Surgery

BACKGROUND

There are many ways in which computer-assisted orthopedic and trauma surgery (CAOS) procedures can help surgeons to plan and execute an intervention.

METHODS

This study is based on data derived from a selective search of the literature in the PubMed database, supported by a Google Scholar search.

RESULTS

For most applications the evidence is weak. In no sector did the use of computer-assisted surgery yield any relevant clinical or functional improvement. In trauma surgery, 3D-navigated sacroiliac screw fixation has become clinically established for the treatment of pelvic fractures. One randomized controlled trial showed a reduction in the rate of screw misplacement: 0% with 3D navigation versus 20.4% with the conventional procedure und 16.6% with 2D navigation. Moreover, navigation-assisted pedicle screw stabilization lowers the misplacement rate. In joint replacements, the long-term results showed no difference in respect of clinical/functional scores, the time for which the implant remained in place, or aseptic loosening.

CONCLUSION

Computer-assisted procedures can improve the precision of certain surgical interventions. Particularly in joint replacement and spinal surgery, the research is moving away from navigation in the direction of robotic procedures. Future studies should place greater emphasis on clinical and functional results.

A new adjustable parallel drill guide for internal fixation of femoral neck fracture: a developmental and experimental study

Background

Internal fixation is one treatment for femoral neck fracture. Some devices and techniques reported improved accuracy and decreased fluoroscopic time. However, these are not widely used nowadays due to the lack of available special instruments and techniques. To improve the surgical procedure, the authors designed a new adjustable drill guide and tested the efficacy of the device.

Methods

The authors developed a new adjustable drill guide for cannulated screw guide wire insertion for multiple screw fixation. Eight orthopaedic surgeons performed the experimental study to evaluate the efficacy of this device. Each surgeon performed guide wire insertion for multiple screw fixation in six synthetic femurs: three times with the new device and three times with the conventional technique. The fluoroscopic time, operative time and surgeon satisfaction were evaluated.

Results

In the operations with the new adjustable drill guide, the fluoroscopic and operative times were significantly lower than the operations with the conventional technique (p < 0.05). The mean score for the level of satisfaction of this device was also statistically significantly better (p = 0.02) than the conventional technique.

Conclusions

The fluoroscopic and operative times with the new adjustable drill guide were reduced for multiple screw fixation of femoral neck fracture and the satisfaction of the surgeons was good.

2D-fluoroscopic based navigation for Gamma 3 nail insertion versus conventional procedure- a feasibility study

Background

Intramedullary nailing is a standard surgical procedure for fixation of proximal femoral fractures, but is associated with considerable radiation exposure for controlling the implant placement, due to the percutaneous insertion technique.

The aim of this study was the evaluation of potential benefits of 2D-fluoroscopic based navigation focused on the reduction of radiation exposure, a decrease of procedure time, as well as an increase of accuracy for Gamma3 nail insertions.

Methods

Twenty randomized Gamma3 nail insertions were performed in non-fractured synthetic femora according to the manufactures operation guidelines (group I) or with use of a 2D-fluoroscopic based navigation system (group II). Time of different steps of the procedure and the radiation exposure were measured, as well as the accuracy evaluated in postoperative CT scans.

Results and discussion

All Gamma3 nails were placed without any technical problems. Independent of the used procedure, the overall operating time (group I: 584 ± 99.2 sec; group II: 662 ± 64.9 sec; p=0.06) and accuracy of the final nail-positions were equivalent, but the radiation exposure was significantly reduced (92% reduction in fluoroscopic images and 91% reduction in fluoroscopic time, p< 0.01), using the 2D fluoroscopic based navigation procedure.

Conclusions

2D-fluoroscopic based navigation for Gamma3 nail insertion facilitates a relevant reduction of radiation exposure with equivalent accuracy of the final implant position and no prolonged operating time. This promising procedure modification is independent of different cephalomedullary implant manufacturers and specific implant designs, but needs to be evaluated in further clinical settings.

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.

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

Accurate placement of cannulated screws is essential to ensure fixation of medial femoral neck fractures. The conventional technique may require multiple guide wire passes, and relies heavily on fluoroscopy. A computer-assisted planning and navigation system based on 2D fluoroscopy for guide wire placement in the femoral neck has been developed to improve screw placement. The planning process was supported by a tool that enables a virtual radiation-free preview of X-ray images. This is called "zero-dose C-arm navigation". For the evaluation of the system, six formalin-fixed cadaveric full-body specimens (12 femurs) were used. The evaluation demonstrated the feasibility of fluoroscopically navigated guide wire and implant placement. Use of the novel system resulted in a significant reduction in the number of fluoroscopic images and drilling attempts while achieving optimized accuracy by attaining better screw parallelism and enlarged neck-width coverage. Operation time was significantly longer in the navigation assisted group. The system has yielded promising initial results; however, additional studies using fractured bone models and with extension of the navigation process to track two bone fragments must be performed before integration of this navigation system into the clinical workflow is possible, and these studies should focus on reducing the operation time.

[Evaluation of a 2D fluoroscopy-based navigation system for insertion of femoral neck screws. An experimental study]

INTRODUCTION

The aim of this study was the evaluation of a new computer-assisted planning and navigation system based on 2D-fluoroscopy for guidewire insertion in order to perform cannulated screw placement into the femoral neck. The image acquisition process was supported by a radiation-saving procedure called Zero-dose C-arm navigation.

MATERIAL AND METHODS

In the context of a sawbone study, we performed insertion of 3 cannulated screws positioned under navigation control as well as using the conventional technique in 12 sawbones. Both procedures were performed using open and closed techniques.

RESULTS

The computer-assisted technique significantly reduced the amount of intraoperative fluoroscopic images (open technique: -14±3 images, closed technique: -29.4±6 images). Drilling attempts were reduced in the computer-assisted groups (open technique: -1.2±1 attempts, closed technique: -1.7±1.5 attempts) and the femoral neck area covered by the screws was greater in the navigation-assisted groups (open technique: +32.1±16.3 mm(2), closed technique: +32.6±14.9 mm(2)), There was no difference concerning parallelism of the screws or perforation of femoral neck or head. The operation time was significantly longer in the navigation-assisted groups (open technique: +24.2±2.1 min, closed technique: +22.8±5.8 min).

CONCLUSION

The addition of computer-assisted planning and surgical guidance supported by Zero-dose C-arm navigation can be useful for the fixation of medial femoral neck fractures with cannulated screws. Further studies with the goal of reducing the operation time are indispensable before integrating this navigation system into the clinical workflow.

Arthroscopic-assisted fluoroscopic navigation for retrograde drilling of a talar osteochondral lesion

Level of Evidence: V, Expert Opinion

Current concepts and applications of computer navigation in orthopedic trauma surgery

Navigation has become widely integrated into regular endoprosthetic procedures, but clinical use of navigation systems in orthopaedic trauma has only been implemented in a few indications. Navigation systems enable an accuracy of 1 mm or 1 degree. Navigation can achieve higher precision when it is combined with different imaging modalities, including preoperative computer tomography (CT), intraoperative CT, two-dimensional fluoroscopy, and, recently, intraoperative three-dimensional fluoroscopy. The precision of the navigation system can be influenced by the surgeon as well as by the camera system, type of reference marker, and the registration process. Recent developments in orthopedic trauma navigation allow for bilateral femoral anteversion measurements, noninvasive registration of an uninjured thigh, and intraoperative three-dimensional fluoroscopy-based pedicle screw placement. Although the use of navigation has provided initial positive results in trauma care, prospective clinical studies remain to be performed.

Decreased navigated drilling time using an external guide stabilising device

INTRODUCTION

Computer navigation in orthopaedic procedures can improve accuracy and decrease radiation time compared to traditional fluoroscopy. Many different applications are now available, and drilling is commonly used amongst them. Aside from additional set up time required, the drilling procedure itself may take a significant amount of time. We hypothesised that using an external stabilising guide which can be set anywhere in space can decrease then time necessary for navigated drilling.

METHODS

Foam blocks, 80 mm in length and a density similar to cancellous bone, were obtained. Small discs were placed on one end as drilling targets. Using an Iso-C 3D navigation system, 20 navigated drilling trials were performed under each of two conditions: freehand, and with the use of a drill stabilising guide attached to an operating table. The time and accuracy of the two methods were compared.

RESULTS

The time required for the entire navigation procedure was significantly less using the stabilising arm compared to drilling freehand with navigation (4.5 min versus 5.8 min, p=0.009). There was no significant difference in accuracy between the two methods.

CONCLUSION

Using a guide which attaches to the table and allows the surgeon to fix the drill sleeve when the desired vector is chosen allows for faster navigated drilling. This was easy to set up and attach to the table, and did not diminish accuracy of drilling an intended target.

Improved accuracy of navigated drilling using a drill alignment device

Drilling procedures are common in orthopedic surgery and are one specific task that may be aided by computer-assisted navigation. However, the inherent flexibility of drill bit bending may make this the limiting factor in achieving acceptable accuracy when using these systems. We designed an alignment device that was fit to a standard orthopedic drill that allowed an extension of the stabilizing point of a drill bit. In foam blocks with a similar density as cancellous bone, 208 total navigated drilling trials were performed, using four different sized drill bits (2.5, 3.2, 3.5, and 4.5 mm) with and without the alignment device. Drilling tracts of 80 mm were made towards an intended target on the other side of the block. Reduction in deviation from the intended target was significantly improved with the use of the guide, ranging from 33% to 45% for the four drill sizes. For the trails using the alignment device, the 2.5-mm drill bit was significantly less accurate than the three larger drills. Our results demonstrate that the use of external devices to augment drill bit stabilization can improve drilling accuracy. This may have particular importance when using navigation systems to drill into small anatomic confines.

[Precision of guidewire placement--can it be improved by applying the new, isocentric aiming principle?]

BACKGROUND

Exact placement of a guidewire is difficult for the less experienced surgeon as this complex 3D task usually is controlled by means of 2D fluoroscopic projections. The new isocentric aiming principle presented here splits up the 3D task into two planar, 2D steps. Movements of the guidewire to achieve correct placement are limited to one plane per step and can therefore be exactly controlled by fluoroscopy. The fluoroscopic projection needs to be changed only once in between the two steps.

METHODS

The isocentric aiming principle became applicable to the proximal femur region by means of a mechanical aiming device. We have done an experimental study in order to compare the new isocentric aiming principle to the freehand aiming technique which is routinely applied. We documented the precision of guidewire placement achieved (angular deviation of the guidewire in two projections, linear deviation of the actual from the intended entry point), number of fluoroscopic controls, and procedure time when guidewire placement is done by an experienced and by an inexperienced surgeon.

RESULTS

When applying the isocentric aiming principle the inexperienced surgeon succeeded in fixing the entry angle of the guidewire more precisely both in the AP [1.3 degrees (0.0-2.0 degrees ) versus 2.3 degrees (0.0-9.0 degrees ), p=0.034] as well as in the axial view [1.0 degrees (0.0-2.5 degrees ) versus 6.5 degrees (0.0-12.0 degrees ), p=0.036]. Linear displacement was not significantly different between the two methods: 4.4 (0.7-9.6) mm deviation with the isocentric aiming principle versus 3.9 (1.6-5.7) mm, p=0.406, when the freehand technique is applied. When applying the isocentric aiming principle for guidewire placement the experienced surgeon achieved less precise angulation in the AP view [2.5 degrees (0.0-4.0 degrees ) versus 1.8 degrees (0.0-3.5 degrees ), p=0.061], improved precision in the axial view [2.0 degrees (1.0-3.0 degrees ) versus 3.0 degrees (0.0-5.0 degrees ), p=0.074], and a slightly worsened linear displacement [2.5 (1.0-4.2) mm versus 2.0 (1.0-2.6) mm, p=0.131]. Both surgeons needed less fluoroscopic controls when using the isocentric aiming principle instead of the freehand aiming method: inexperienced surgeon: 8.0 controls (7.0-16.0) instead of 13.0 controls (7.0-16.0), p=0.043; experienced surgeon: 14.5 controls (8.0-26.0) instead of 16.5 controls (12.0-33.0), p=0.282. However due to the additional time needed to fix and align the aiming device to the bone both surgeons required increased procedure time when using the isocentric aiming principle: 4.3 (3.0-6.9) min instead of 2.6 (2.2-4.0) min, p=0.005, for the inexperienced surgeon and 3.3 (2.3-4.3) min instead of 1.9 (1.4-2.8) min, p=0.001, for the experienced surgeon.

CONCLUSIONS

Based on the experimental results we would suggest clinical application of the isocentric aiming principle especially for the less experienced surgeon. Increased precision would outweigh the drawback of a slightly prolonged procedure time. X-ray exposure may also be reduced when using the isocentric aiming principle for guidewire placement. However our results have to be verified by a clinical study beforehand. The isocentric aiming principle can also be applied in other situations that allow for two orthogonal projections for guidewire placement.