Radiological outcome and intraoperative evaluation of a computer-navigation system for femoral nailing: a retrospective cohort study

Description of new sign of integral (∫) for rotational deformity of distal femur

PURPOSE

Femur shaft fractures commonly occur due to high velocity trauma and most of them are fixed with nailing. Malrotation is common after fixation. A rotational malalignment more than 30° is a deformity which requires correction. Various techniques described for rotational deformities are: the 'cable techniques' for the determination of varus-valgus malalignment; the 'hyperextension test', 'radiographic recurvatum sign', 'tibial plateau sign', and 'meterstick technique' for length analysis; and the 'hip rotation test', 'lesser trochanter shape sign', 'cortical step sign', and 'diameter difference sign' for rotational analysis. We describe integration sign at the medial or lateral aspect of notch of femur in fixed internal or external rotation due to condensation of trabeculae.

METHODS

This is a prospective observational study. Informed consent was taken, and this study was approved by institutional review board. C arm imaging study of 50 knees was done at our institution in which rotational profile of distal femur was analyzed In 3 different views -AP , Internal and external rotation views. The rotation views were taken sequentially and each observer was asked to identify the sign at its appearance and at rotation when it was best seen. All the observers were asked to draw the sign on linear line diagram of distal femur. The data was analysed statistically.

RESULTS

Sign of integral (∫) for rotational deformity was seen at Mean external rotation of  22±1.71 with a range of 19 degree to 25 degree and  Mean internal rotation of 15.78±1.21 with a range of 14 degree to 18 degree.

CONCLUSION

The integration sign can be used as intraoperative C arm sign to understand the rotational deformity of distal fragment of femur. This helps the surgeon to understand the alignment and revise if needed intraoperatively. If combined with position of lesser trochanter, this will give alignment for both proximal as well as distal fragment of femur.

Minimally Invasive Derotational Osteotomy of Long Bones: Smartphone Application Used to Improve the Accuracy of Correction

Correction of rotational malalignments caused by fractures is essential as it may cause pain and gait disturbances. This study evaluated the intraoperative use of a smartphone application (SP app) to measure the extent of corrective rotation in patients treated using minimally invasive derotational osteotomy. Intraoperatively, two parallel 5 mm Schanz pins were placed above and below the fractured/injured site, and derotation was performed manually after percutaneous osteotomy. A protractor SP app was used intraoperatively to measure the angle between the two Schanz pins (angle-SP). Intramedullary nailing or minimally invasive plate osteosynthesis was performed after derotation, and computerized tomography (CT) scans were used to assess the angle of correction postoperatively (angle-CT). The accuracy of rotational correction was assessed by comparing angle-SP and angle-CT. The mean preoperative rotational difference observed was 22.1°, while the mean angle-SP and angle-CT were 21.6° and 21.3°, respectively. A significant positive correlation between angle-SP and angle-CT was observed, and 18 out of 19 patients exhibited complete healing within 17.7 weeks (1 patient exhibited nonunion). These findings suggest that using an SP app during minimally invasive derotational osteotomy can result in accurate correction of malrotation of long bones in a reproducible manner. Therefore, SP technology with integrated gyroscope function represents a suitable alternative for determination of the magnitude of rotational correction when performing corrective osteotomy.

[Does navigation still have a value in trauma surgery?]

BACKGROUND

Navigation systems are supposed to increase precision and support surgeons while they perform certain interventions. 2D, or nowadays 3D, systems are used in image-based approaches. Image-free navigation uses 3D printing.

INDICATIONS

There are several studies on navigation procedures in trauma surgery. In contrast to limb surgery, the use of 3D navigation in pelvic and spine surgery is already well established. Navigation is especially regularly used to treat fractures of the posterior pelvic ring and for posterior stabilization of the cervical spine.

REQUIREMENTS

To be able to utilize navigation systems optimally, the learning curve should be completed, and the technique should be used regularly. In addition, the surgeon should know the surgical technique without navigation in order to recognize potential errors of the navigation.

ADVANTAGES AND DISADVANTAGES

Advantages include increased patient safety, reduction in radiation exposure and less invasive surgical procedures. However, among other disadvantages, initial costs are high.

Augmented Reality (AR) in Orthopedics: Current Applications and Future Directions

PURPOSE OF REVIEW

Imaging technologies (X-ray, CT, MRI, and ultrasound) have revolutionized orthopedic surgery, allowing for the more efficient diagnosis, monitoring, and treatment of musculoskeletal aliments. The current review investigates recent literature surrounding the impact of augmented reality (AR) imaging technologies on orthopedic surgery. In particular, it investigates the impact that AR technologies may have on provider cognitive burden, operative times, occupational radiation exposure, and surgical precision and outcomes.

RECENT FINDINGS

Many AR technologies have been shown to lower provider cognitive burden and reduce operative time and radiation exposure while improving surgical precision in pre-clinical cadaveric and sawbones models. So far, only a few platforms focusing on pedicle screw placement have been approved by the FDA. These technologies have been implemented clinically with mixed results when compared to traditional free-hand approaches. It remains to be seen if current AR technologies can deliver upon their multitude of promises, and the ability to do so seems contingent upon continued technological progress. Additionally, the impact of these platforms will likely be highly conditional on clinical indication and provider type. It remains unclear if AR will be broadly accepted and utilized or if it will be reserved for niche indications where it adds significant value. One thing is clear, orthopedics' high utilization of pre- and intra-operative imaging, combined with the relative ease of tracking rigid structures like bone as compared to soft tissues, has made it the clear beachhead market for AR technologies in medicine.

Custom 3D-Printed Cutting Guides for Femoral Osteotomy in Rotational Malalignment Due to Diaphyseal Fractures: Surgical Technique and Case Series

Femoral shaft fractures are one of the most common injuries in trauma patients. The gold standard treatment consists of closed reduction and intramedullary nailing, providing a high fracture healing rate and allowing early mobilization. However, rotational malalignment is a well-known complication following this procedure, and excessive femoral anteversion or femoral retroversion can trigger functional complaints. In order to achieve the ideal degree of femoral rotation, a 3D planning and printing cutting guides procedure was developed to correct femoral malrotation. A patient series with malalignment after a femoral diaphyseal fracture was operated on with the customized guides and evaluated in this study. Computed tomography scans were performed to accurately determine the number of degrees of malrotation, allowing the design of specific and personalized surgical guides to correct these accurately. Once designed, they were produced by 3D printing. After surgery with the customized guides to correct femoral malrotation, all patients presented a normalized anteversion angle of the femur (average −10.3°, range from −5° to −15°), according to their contralateral limb. These data suggest that the use of customized cutting guides for femoral osteotomy is a safe and reproducible surgical technique that offers precise results when correcting femoral malrotation.

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.

Development of an intraoperative 3D C-arm technique for torsion control of femur fractures: a cadaver study

AIM

This study aims to test the accuracy and feasibility of a measurement of femoral torsion of a 3D C-arm system (Linea aspera method) in a cadaver setting.

MATERIALS AND METHODS

A total of 11 intact femora were used. Schanz screws were inserted in the femoral bone in a parallel manner with the help of a fixed drill sleeve. Femur bones were then fractured in a controlled manner and three different internal and external torsion angles were fixed with the help of a Goniometer. After that, a 3D scan was performed. The 3D data set was analyzed using a radiologic software (Visage 7, Visage Imaging Inc, USA). Measurements were then compared in the two methods with a dependent t test.

RESULTS

Specific measurements for different angles did not show any differences between those two utilities.

CONCLUSION

Intraoperative estimation of femoral antetorsion using a 3D C-Arm system and the Linea aspera method seems to be an accurate and feasible method. Nevertheless, more studies with higher patient numbers, comparison to CT seems to be the next step and can be recommended.

Intraoperative use of cortical step sign and diameter difference sign: Accuracy, inter-rater agreement and influence of surgical experience in subtrochanteric transverse fractures

BACKGROUND

The cortical step sign (CSS) and diameter difference sign (DDS) are radiographic tools for torsional alignment control in intramedullary nailing. They have been found to be highly relevant in objective radiographic measurements, but for intraoperative visual identification they lack sufficient evidence yet. The aim of this experimental study was to evaluate their (1) accuracy, (2) inter-rater agreement, (3) predictors of correct identification for clinically relevant maltorsion (CRM: ≥15°), and (4) positive and negative predictive values.

HYPOTHESIS

Sensitivity and specificity of CSS and DDS in visual identification of CRM are comparable to those in objective measurement.

MATERIAL AND METHODS

Six observers of three different levels of surgical experience evaluated 50 a.p. and 50 lateral views of subtrochanteric fractures of cadaveric specimens with internal/external maltorsion from 0° to 30° to assess for CSS, DDS, and CRM. (1) Sensitivity and specificity were evaluated. Percentage agreement and Cohen's Kappa were used to evaluate accuracy as agreement with measured/true values and (2) inter-rater agreement. To determine (3) significant predictors of correct identification of the CSS, DDS, and CRM, a mixed-effects logistic model was constructed, and (4) predictive values were calculated.

RESULTS

(1) Sensitivities of CSS and DDS for CRM (0.99±0.03 and 0.88±0.06) were close to those in objective measurement (1.00 and 0.90). So were specificities (0.25±0.08 and 0.47±0.17 vs. 0.32 and 0.47). Agreement percentage for CSS was high (90-94%, kappa 0.40-0.69), for DDS and CRM it was slightly lower (74-82%, kappa 0.34-0.57 and 62-76%, kappa 0.26-0.49). (2) Inter-rater agreement also showed the highest values for CSS (88-96%, kappa 0.51-0.73) with slightly lower values for DDS (74-84%, kappa 0.36-0.63) and CRM (62-84%, kappa 0.21-0.68). (3) Training level and the magnitude of maltorsion were found the most relevant predictors of a correct identification of CSS/DDS/CRM. (4) DDS showed a higher positive predictive value (73.1%), CSS a higher negative predictive value (93.5%).

DISCUSSION

We found visual identification of CSS and DDS to be almost as accurate as objective measurement in the detection of CRM. Estimation of maltorsion is not sufficiently reliable, but a negative CSS excludes a CRM with high probability. Both signs should be applied by experienced surgeons.

LEVEL OF EVIDENCE

Level III, experimental setting, non-randomised experimental trial.

[3D-printing in trauma surgery : Planning, printing and processing]

Possible use of 3D-printing technology in orthopedic surgery ranges from preoperative planning to dedicated counselling with patients by the use of individual 3D models, intraoperative surgery tools or implants and various other applications. This article describes a technique for the creation of intraoperative tools with which the process from computed tomography (CT) images to 3D-printed tools in trauma surgery can safely be administered. For segmentation of CT images a range of different software options is available. The standard triangulation file created in this way (file ending: .stl) must subsequently be post-processed. By the use of the digital casts from bone and fractures in computer-aided design (CAD) programs implants and patient individual tools are created, which can range from ortheses to protheses to intraoperative saw guides.

Effect of inherent tibial asymmetry on leg length discrepancy measurements after intramedullary nailing of comminuted femoral shaft fractures

Introduction: Locked intramedullary nailing (IMN) is the standard treatment for femoral shaft fractures in adults with high rates of union and relatively low rates of complications. Leg length discrepancy (LLD) after IMN of femoral shaft fractures is common, and is reported in 20–43% of cases. A known surgical challenge when trying to obtain equal leg lengths is comminuted fracture, which results in a loss of bony landmarks that guide reduction. The purpose of this study was to assess the effect of inherent tibial asymmetry on LLD measurements after IMN.

Methods: Postoperative CT scanograms were performed on 79 consecutive patients after locked IMN for comminuted femoral shaft fracture. Leg lengths were determined by measurements taken from the scout view of a CT scanogram. Calculations of discrepancy were made for both femurs, tibias, and total leg length. Assessment was also made on the frequency wherein the tibial discrepancy compounded the femoral discrepancy. In situations where a limb segment was exactly symmetric to the contralateral side, the total leg was not regarded as a having compounded asymmetry.

Results: Notable discrepancies were found in tibial length that significantly departed from the null of symmetry (p < 0.0001). Forty-two patients (53.2%) were found to have a tibial asymmetry of 3 mm or more, and 20 patients (25.3%) were found to exhibit a difference of 6.3 mm or more. Median femoral discrepancy was 5.3 mm and median tibial discrepancy was 3.0 mm. Seven patients were found to be asymmetric in total leg length as a consequence of underlying tibial asymmetry. Conversely, 11 patients benefited from their tibial asymmetry, which compensated for femoral asymmetry after IMN.

Conclusion: Tibial symmetry cannot be assumed. If not accounted for, inherent tibial asymmetry may influence LLD after IMN of femur fractures.

Radiographic cortical thickness parameters as predictors of rotational alignment in proximal femur fractures: A cadaveric study

Radiographic assessment tools such as the cortical step sign (CSS) or the diameter difference sign (DDS) aim to identify clinically relevant rotational malalignment after long bone fracture fixation. We aimed to analyze the effect of rotational malalignment on CSS and DDS parameters in a subtrochanteric fracture model and to construct a prognostic model to identify clinically relevant rotational malalignment. A subtrochanteric transverse osteotomy was set in human femora. Rotation was set stepwise from 0° to 30° in internal and external rotation. Images were obtained using a C-arm and transferred for measuring the medial cortical thickness (MCT), lateral cortical thickness (LCT), femoral diameter (FD) in AP and the anterior cortical thickness (ACT) as well as the posterior cortical thickness (PCT) and the FD of the proximal and the distal main fragment. There were significant differences between the various levels of rotation for each of the absolute values of the evaluated variables. MCT, PCT and FD (AP & lat.) were the most affected parameters. In internal rotation, the MCT, PCT and the FD were the most affected variables. The parameters with the highest correlation with femoral rotation were ACT, PCT and FD. A model combining ACT, LCT, PCT and FD AP was most suitable model in identifying rotational malalignment. The best prediction of clinically relevant rotational malalignment was obtained with the FD and the PCT. The CSS and the DDS are promising tools for detecting rotational deformities of the proximal femur and should be used intra- and postoperatively. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Minimizing Leg Length Discrepancy After Intramedullary Nailing of Comminuted Femoral Shaft Fractures: A Quality Improvement Initiative Using the Scout Computed Tomography Scanogram

OBJECTIVES

To prevent leg length discrepancy (LLD) after locked femoral nailing in patients with comminuted femoral shaft fractures.

DESIGN

Prospective consecutive case series aimed at quality improvement.

SETTING

Level 1 Trauma Center PATIENTS:: Ninety-eight consecutive patients with a comminuted femoral shaft fracture underwent statically locked intramedullary nailing, with a focused attempt at minimizing LLD during surgery.

INTERVENTION

A computed tomography scanogram of both legs was performed on postoperative day 1 to assess for residual LLD. Patients were offered the option to have LLD >1.5 cm corrected before discharge.

MAIN OUTCOME MEASURE

LLD >1.5 cm.

RESULTS

Twenty-one patients (21.4%) were found to have an LLD >1.5 cm. An LLD >1.5 cm occurred in 10/55 (18%) antegrade nail patients and 11/43 (26%) retrograde nail patients (P = 0.27). No difference was noted based on the mechanism of injury, surgeon training and OTA/AO type B versus C injury. Ninety of 98 patients left with <1.5 cm LLD, 13/21 had a correction all to ≤0.6 cm, and 8 decided to accept the LLD and declined early correction.

CONCLUSIONS

No patient left the hospital with an LLD >1.5 cm after locked intramedullary nailing for a comminuted femoral shaft fracture without being informed and the option of early correction. We recommend using a full-length computed tomography scanogram after IM nailing of comminuted femur fractures to prevent iatrogenic LLD.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

On-the-fly augmented reality for orthopedic surgery using a multimodal fiducial

Fluoroscopic x-ray guidance is a cornerstone for percutaneous orthopedic surgical procedures. However, two-dimensional (2-D) observations of the three-dimensional (3-D) anatomy suffer from the effects of projective simplification. Consequently, many x-ray images from various orientations need to be acquired for the surgeon to accurately assess the spatial relations between the patient's anatomy and the surgical tools. We present an on-the-fly surgical support system that provides guidance using augmented reality and can be used in quasiunprepared operating rooms. The proposed system builds upon a multimodality marker and simultaneous localization and mapping technique to cocalibrate an optical see-through head mounted display to a C-arm fluoroscopy system. Then, annotations on the 2-D x-ray images can be rendered as virtual objects in 3-D providing surgical guidance. We quantitatively evaluate the components of the proposed system and, finally, design a feasibility study on a semianthropomorphic phantom. The accuracy of our system was comparable to the traditional image-guided technique while substantially reducing the number of acquired x-ray images as well as procedure time. Our promising results encourage further research on the interaction between virtual and real objects that we believe will directly benefit the proposed method. Further, we would like to explore the capabilities of our on-the-fly augmented reality support system in a larger study directed toward common orthopedic interventions.

Evaluation of malrotation following intramedullary nailing in a femoral shaft fracture model: Can a 3D c-arm improve accuracy?

INTRODUCTION

Difficulty determining anatomic rotation following intramedullary (IM) nailing of the femur continues to be problematic for surgeons. Clinical exam and fluoroscopic imaging of the hip and knee have been used to estimate femoral version, but are inaccurate. We hypothesize that 3D c-arm imaging can be used to accurately measure femoral version following IM nailing of femur fractures to prevent rotational malreduction.

METHODS

A midshaft osteotomy was created in a femur Sawbone to simulate a transverse diaphyseal fracture. An intramedullary (IM) nail was inserted into the Sawbone femur without locking screws or cephalomedullary fixation. A goniometer was used to simulate four femoral version situations after IM nailing: 20° retroversion, 0° version, 15° anteversion, and 30° anteversion. In each simulated position, 3D c-arm imaging and, for comparison purposes, perfect lateral radiographs of the knee and hip were performed. The femoral version of each simulated 3D and fluoroscopic case was measured and the results were tabulated.

RESULTS

The measured version from the 3D c-arm images was 22.25° retroversion, 0.66° anteversion, 19.53° anteversion, and 25.15° anteversion for the simulated cases of 20° retroversion, 0° version, 15° anteversion, and 30° anteversion, respectively. The lateral fluoroscopic views were measured to be 9.66° retroversion, 12.12° anteversion, 20.91° anteversion, and 18.77° anteversion for the simulated cases, respectively.

CONCLUSION

This study demonstrates the utility of a novel intraoperative method to evaluate femur rotational malreduction following IM nailing. The use of 3D c-arm imaging to measure femoral version offers accuracy and reproducibility.

Malalignment after minimally invasive plate osteosynthesis in distal femoral fractures

INTRODUCTION

Although minimally invasive plate osteosynthesis (MIPO) is a preferred operative treatment for fractures of the distal femur, malalignment is a significant concern because of indirect reduction of the fracture. The purpose of this study, therefore, was to evaluate radiologic alignment after MIPO for distal femoral fractures.

PATIENTS AND METHODS

Of the 138 patients with fracture of the distal femur who underwent MIPO, we enrolled 51 patients in whom bilateral rotational alignment could be assessed by postoperative computed tomography (CT). The patients included 32 men and 19 women, with a mean age of 54.3 years. Thirteen patients had femoral shaft fractures (according to the AO/OTA classification: 32-A, n=2; 32-B, n=6; 32-C, n=5), whereas 38 patients had distal femoral fractures (33-A, n=7; 33-C, n=31). Coronal and sagittal alignments were assessed using simple radiography, whereas rotational alignment was assessed using CT. According to the difference between the affected and unaffected sides, we divided the patients into satisfactory and unsatisfactory groups (reference point of 8°, using Handolin's classification). Thereafter, we determined which factors can lead to malalignment, including fracture location (distal femoral shaft fracture or metaphyseal fracture), fracture pattern (simple fracture, n=15; complex fractures, n=36 patients), coronal and sagittal alignments, and combined ipsilateral long bone fractures.

RESULTS

Coronal and sagittal alignment were satisfactory in 96.2% (average, 2.8°) and 98% (average, 2.2°), respectively, whereas the rotational alignment was satisfactory in 56.9% of patients. Leg length discrepancy was satisfactory in 92.3% of the patients (average, 10.9mm). Concerning rotational malalignment, an unsatisfactory result was obtained in 48.6% of subjects with complex fractures and 26.7% of subjects with simple fractures (p=0.114). No significant correlation was noted between the angular deformity in the coronal and sagittal planes and the degree of rotational alignment (p=0.607 and 0.774, respectively).

CONCLUSIONS

Regardless of the fracture pattern, rotational malalignment may occur at an extremely high rate after MIPO for fractures of the distal femur.

Correction of multiple complex lower limb deformities by intramedullary nailing

A female patient presented to our institution suffering from long bone post-traumatic multiple deformities. Her walking was limited, painful and teetering. It had worsened over the past months. The right leg was shortened by 6 cm compared to the contralateral. The right femur was 18° varus, the right tibia was 16° valgus, the left tibia was 12° varus. Both knee joints showed marked radiographic signs of osteosclerosis. After a thorough study with simulations using paper models, we carried out three osteotomies, two open wedge and one cuneiform, stabilizing them with intramedullary nails. We conducted the operation in two stages, in order to avoid an excessive surgical stress that could give rise to complications such as DVT, fat embolism, and respiratory insufficiency. This allowed a rapid recovery of her weight bearing and walking capacity, reducing significantly also the leg length discrepancy. She progressed uneventfully to healing of the osteotomy sites and she returned to her previous occupation.

One year orthopaedic trauma experience using an advanced interdisciplinary hybrid operating room

Hybrid operating rooms have been used successfully in several surgical specialties, but no data have been published for orthopaedic trauma. We present our one-year orthopaedic trauma experience using a hybrid operating room, which incorporates 3D fluoroscopic imaging as well as navigation capabilities. Data were compiled for a series of 92 cases performed in an advanced hybrid operating room at the level one trauma center in Ulm, Germany. All patients who had surgery performed using this operating room during the first year were included. Setup time and surgical complications using hybrid operating room were recorded and analysed. The hybrid operating room resulted in no higher rate of complication than expected from the same cases in a conventional operating room. The hybrid room did however allow the surgeon to confidently place implants for orthopaedic trauma cases, and was most advantageous for spine and pelvis cases, both minimally invasive and conventional. Further, appropriate reduction and implant position was confirmed with 3D imaging prior to leaving the operating room and obviated the need for postoperative CT scan. Based on our one-year experience, the hybrid operating room is a useful and safe tool for orthopaedic trauma surgery.

Interlocking screws placed with freehand technique and uni-planar image intensification: the "dip-stick" technique

OBJECTIVE

To report our experience with a novel alternative method of freehand interlocking of intramedullary nails. This method requires the use of only anterior-posterior image intensification and an intramedullary guide wire to verify screw placement. Our results are compared with historical results in the literature.

METHODS

A total of 815 patients were treated using this technique from January 2008 to December 2012; 603 patients had fractures of the tibia and 212 had fractures of the femur.

RESULTS

The mean duration of surgery for tibial shaft fractures was 55.6 minutes (range 42-60 minutes) and that for fractures of the femur was 78 minutes (range 50-90 minutes). The mean time for each distal locking was 3.8 minutes (2.5-5.1 minutes), with 7.65 seconds of exposure to radiation during each block.

CONCLUSIONS

The surgical technique is simple, easy and reproducible. Mean time of surgery and radiation exposure was less than that in the literature. A comparative study should be performed.