Computerized navigation for the internal fixation of femoral neck fractures

Long-term outcome of robotic-guided closed reduction internal fixation for Delbet II femoral neck fractures in children

OBJECTIVE

To retrospectively analyze and assess the long-term effectiveness of robotic navigation and traditional closed reduction internal fixation in the treatment of Delbet type II femoral neck fracture in children.

METHODS

A total of fifty-five patients diagnosed with pediatric Delbet type II femoral neck fracture, who were admitted to Foshan Hospital of Traditional Chinese Medicine between January 2018 and June 2022, were included in this study. Among them, 22 cases of nailing under robotic navigation were set as the observation group, and 33 cases of nailing under fluoroscopy of the C-arm machine were set as the control group. All patients had their femoral neck fractures closed and repositioned first. After confirming the satisfactory fracture repositioning under the fluoroscopic view of the C-arm machine, internal fixation was performed by inserting hollow compression screws in the corresponding surgical way.A comparative analysis was conducted between the two groups to assess the disparity in the amount of X-ray exposure during surgery, the number of guide pins inserted, and the duration of the surgical procedure. The quality of comparative fracture reduction was assessed according to the Haidukewych criteria on the first postoperative hip X-ray, and the parallelism and distribution of the comparative screws were measured. The incidence of hip function and postoperative complications according to the Ratliff criteria were evaluated between each of the subgroups at the final follow-up.

RESULTS

Comparison of general information, operation duration, and quality of fracture reduction between the two groups failed to reveal statistically significant results (P > 0.05). The observation group had a lower number of X-ray exposures and guide pin placements compared to the control group, and this difference was statistically significant (P < 0.05).At the last follow-up, the observation group exhibited superior screw parallelism and distribution, as well as hip joint function, compared to the control group, and this difference was statistically significant (P < 0.05). The incidence of complications in the observation group was lower than that in the control group; however, the difference was not statistically significant (P > 0.05).

CONCLUSION

Closed reduction and internal fixation under orthopedic robot navigation can achieve better long-term efficacy in treating Delbet type II femoral neck fracture in children.

Minimally invasive femoral head fracture fixation using three-dimensional navigation: a technical note

Femoral head fractures are rare traumatic injuries that are usually associated with hip dislocations. Open reduction and internal fixation are performed when indicated, but can be associated with a higher risk of avascular necrosis. We report the case of a 24-year-old patient with a Pipkin type II fracture dislocation of the femoral head fixed via a minimally invasive three-dimensional navigated internal fixation technique. This technique minimizes deep soft tissue dissection to the hip capsule and associated vascularity and allows for accurate implant positioning.Level of evidence: Therapeutic case report Level IV.

A Novel Navigation Device for Precise Percutaneous Placement of the Guidewire in Femoral Neck Fracture Cannulated Screw Fixation Surgery

The accuracy of screw placement is a key factor for the stability of the cannulated screws used in the fixation of femoral neck fractures. In this study we designed a navigation device for ensuring the screw reaches the ideal position for optimal fixation. From March 2019 to September 2020, 66 patients with femoral neck fracture were enrolled and divided into 2 groups, one group was treated using the traditional free-hand cannulated screw fixation and the other using the new navigation device with assisted fixation. The effectiveness of the 2 methods was compared based on surgery duration, intraoperative bleeding, number of fluoroscopic examination and guidewire insertion attempts, screw parallelism, and effective fixation area. Fracture healing, complications and hip joint function were assessed after operation. The new navigation device reduced the duration of surgery without causing additional intraoperative bleeding, and significantly reduced number of fluoroscopy examination and guidewire insertion attempts (4.00±1.58 vs. 6.09±1.94 with traditional surgery). The accuracy of screw implantation was improved, as demonstrated by increased screw parallelism (0.71±0.57° vs. 1.66 ±1.01° with traditional surgery) and higher effective fixed area (64.88±10.52 vs. 58.61±9.19 mm2 with traditional surgery). In the postoperative follow-up, except for one case of femoral head necrosis and one case of bone nonunion in the traditional surgical group, the other patients showed fracture healing. There was no significant difference in hip joint function between the 2 groups. The new navigation device enables rapid and accurate guidewire positioning for cannulated screw fixation through simple operation procedures, resulting in good prospect for clinical transformation.

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.

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 (R 2=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.

Quick and Accurate Placement of Cannulated Screws to Internal Fixation of Femoral Neck Fractures Using a Novel Guide Device

INTRODUCTION

Fixation of femoral neck fractures with cannulated screws is an accepted method. This study aimed to compare a novel guide device and conventional technique with regard to the accuracy, operation time, fluoroscopy numbers, and drilling attempts during the insertion of cannulated screws to internal fixation of femoral neck fractures.

METHODS

This retrospective study included 60 patients with intracapsular femoral neck fractures who were treated with cannulated screws from January 2020 to June 2021. Three screws were inserted into the femoral neck by conventional technique or using the novel guide device. The operative time, total drilling attempts, and fluoroscopy numbers were evaluated. The precision of implant placement was evaluated by screw parallelism and spread. The patients were followed for 12-24 months.

RESULTS

The fluoroscopy numbers and operation time of the guide-device-assisted group were shorter than for the conventional group (p < 0.05). The total drilling attempts were significantly lower with the guide device than in the conventional group (p < 0.05). The guide-device-assisted group had better screw parallelism and greater spread than the conventional group (p < 0.05).

CONCLUSIONS

The novel guide device may be an effective assistant instrument for internal fixation of femoral neck fracture with cannulated screws.

Robot-Assisted Versus Conventional Freehand Fluoroscopy-Guided Percutaneous Screw Fixation in Femoral Neck Fractures: A Systematic Review and Meta-analysis

Robotic-assisted navigation for percutaneous femoral neck fracture fixation is a new technology that has shown enhanced intraoperative and postoperative outcomes compared to the conventional freehand fluoroscopy-guided technique. The authors aim to compare robot-assisted femoral neck fracture fixation to conventional freehand fluoroscopy-guided repair. Electronic databases were searched, identifying all observational studies comparing outcomes of both groups. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis were conducted. The primary outcomes included operative duration (minutes), intraoperative bleeding (mL), fluoroscopy exposure, and frequency of intraoperative drilling. The secondary outcomes included Harris scores, healing rate and time, screw accuracy, and postoperative complications. Seven observational studies were identified, enrolling 506 patients. There was a significant difference between the robot-assisted and conventional groups in terms of intraoperative blood loss (mean difference (MD) = -18.83, p ≤ 0.05), fluoroscopy exposure (MD = -1.81, p ≤ 0.05), and intraoperative drilling frequency (MD = -7.35, p < 0.05). There was no significant difference in operative duration between the groups (MD = -0.21, p = 0.66). Most secondary outcomes were improved in the robot-assisted group. Overall, robot-assisted fixation was superior in terms of safety and efficacy.

Robot-assisted cannulated compression screw internal fixation for treatment of femoral neck fracture in children: A case series of ten patients

PURPOSE

To investigate the safety and efficacy of robot-assisted cannulated compression screw internal fixation in the treatment of femoral neck fracture in children.

METHODS

We retrospectively reviewed the data of ten children with femoral neck fractures treated by robot-assisted internal fixation from January 2020 to June 2021. The clinical and radiological characteristics, operation duration, and fluoroscopy frequency of robot-assisted screws placement together with the complications and function were evaluated. At the 12-month follow-up, the hip joint function was evaluated using the Ratliff classification.

RESULTS

Ten children, six boys and four girls, aged 4-14 years were included. There were eight type II and three type III femoral neck fractures using the Delbet classification. In the process of robot-assisted internal fixation, the median of fluoroscopy frequency was 22 times and the median of operation duration was 47 min. The median of screw parallelism was 1.33° and 0.66° on the anteroposterior and lateral x-ray films, and the median of screw distribution was 41.86% and 44.93% on the anteroposterior and lateral x-ray films, respectively. At the 12-month follow-up, there were two cases of femoral head necrosis, and fracture healing was achieved in all patients, of which eight fractures were excellent and three were good by the Ratliff function classification.

DISCUSSION

The application of robot-assisted cannulated compression screw internal fixation could help us achieve more safe and accurate screw placement, as well as a good treatment effect for children's femoral neck fractures.

LEVEL OF EVIDENCE

Level IV. retrospective case series.

Computer-assisted cannulated screw internal fixation versus conventional cannulated screw internal fixation for femoral neck fractures: a systematic review and meta-analysis

Objective

To compare the effects between computer-assisted and traditional cannulated screw internal fixation on treating femoral neck fracture.

Methods

The search was conducted in Embase, Pubmed, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI) and Wanfang Database from the beginning to August 2020. RevMan5.4 software, which was provided by the International Cochrane Group, was used for the meta-analysis comparing the differences in operation time, intraoperative bleeding volume, fluoroscopy frequency, fracture healing time, total drilling times, Harris score, fracture healing rate, and femoral head necrosis rate between computer-assisted and traditional methods groups.

Results

A total of 1028 patients were included in 16 studies. Primary outcome indicators: Compared with the traditional method group, the computer-assisted group had less operative time (2RCTs, P < 0.00001; 8 non-RCTs, P = 0.009; Overall, P < 0.00001), intraoperative bleeding (1 RCTs, P < 0.00001; 9non-RCTs, P < 0.00001; Overall, P < 0.00001), femoral head necrosis rate (1 RCT, P = 0.11;7 non-RCTs, P = 0.09; Overall, P = 0.02) and higher Harris scores (1 RCT, P < 0.0001; 9 non-RCTs, P = 0.0002; Overall, P < 0.0001), and there were no significant differences in fracture healing rate between the two groups (5 non-RCTs, P = 0.17). Secondary outcomes indicators: The computer-assisted group had a lower frequency of intraoperative fluoroscopy and total number of drills compared with the traditional method group, while there was no significant difference in fracture healing time.

Conclusion

Compared with the traditional hollow screw internal fixation on the treatment of femoral neck fracture, computer-assisted percutaneous cannulated screw fixation can shorten the operation time and improve the operation efficiency and reduce the X-ray injury of medical staff and help patients obtain a better prognosis. Therefore, computer-assisted percutaneous cannulated screw fixation is a better choice for the treatment of femoral neck fracture.

Study registration PROSPERO registration number CRD42020214493.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02806-7.

Robot-assisted fracture fixation in orthopaedic trauma surgery: a systematic review

Objective:

To investigate the applications of robot-assisted surgery and its effect on surgical outcomes in orthopaedic trauma patients.

Data Sources:

A search was performed in PubMed and Embase for articles in English, Dutch, German, or French, without restrictions on follow-up times, study size, or year of publication.

Study Selection:

Studies were included if they investigated patients undergoing robot-assisted fracture fixation surgery for orthopaedic trauma.

Data Extraction:

Outcomes studied were operating time, fluoroscopy time/frequency, complications, functional outcomes, intraoperative blood loss, fracture healing, and screw placement accuracy. Critical appraisal was done by using the Methodological Index for Non-Randomized Studies.

Data Synthesis:

Narrative review.

Conclusions:

A total of 3832 hits were identified with the search and 8 studies were included with a combined total of 437 included patients, 3 retrospective cohort studies, 2 prospective cohort studies, 1 cohort study not otherwise specified, 1 case series, and 1 randomized controlled trial. Four studies investigated pelvic ring fractures, 3 studies investigated femur fractures, and 1 study investigated scaphoid fractures. Seven investigated percutaneous screw fixation and 1 studied intramedullary nail fixation. One robotic system was used across all studies, the TiRobot, and all procedures were performed in China. The limited evidence suggests that that robot-assisted orthopaedic trauma surgery may reduce operating time, use of fluoroscopy, intraoperative blood loss, and improve screw placement accuracy, but the overall quality of evidence was low with a high risk of bias. Robot-assisted fracture fixation does not appear to lead to better functional outcomes for the patient.

Level of evidence: III

ADAPT system is a dramatic advance in computer-assisted surgery for femoral trochanteric fractures

Introduction: In recent years, computer-assisted surgery has made it possible to undergo surgery with a high degree of precision. This study aimed to investigate the usefulness of computer-assisted surgery for femoral trochanteric fractures using the ADAPT (ADAptive Positioning Technology) system. Methods: A total of forty patients with femoral trochanteric fracture underwent intramedullary nailing for fracture fixation: in twenty patients, the ADAPT system (ADAPT group), and in the other twenty, it was not used (control group). The operative time, intraoperative fluoroscopy time, tip apex distance (TAD), and tip to head surface distance (TSD) were measured and compared between the two groups to assess the efficiency and accuracy of the surgery. Results: The operative time was significantly shorter (P < 0.05), intraoperative fluoroscopy time was significantly reduced (P < 0.01), and implant placement was significantly better in the ADAPT group (P < 0.01). Conclusion: Navigation systems have been developed to improve the efficiency of surgery. The ADAPT system was considered a very useful device for intramedullary nailing of femoral trochanteric fractures, as it reduced the intraoperative fluoroscopy time and improved the accuracy of implant placement, also reducing the operative time.

TiRobot-Assisted Percutaneous Cannulated Screw Fixation in the Treatment of Femoral Neck Fractures: A Minimum 2-Year Follow-up of 50 Patients

Objective

To assess the long‐term clinical efficacy of TiRobot‐assisted percutaneous cannulated screw fixation in the treatment of femoral neck fractures.

Methods

This retrospective study included 50 patients with unilateral femoral neck fractures who were treated with TiRobot‐assisted percutaneous cannulated screw fixation from September 2017 to May 2018. After at least 2 years of follow‐up, the results of treatment, including operation duration, frequency of fluoroscopy use, intraoperative bleeding, hospital stay, medical expense, screw placement accuracy, rate of fracture healing and necrosis of the femoral head, and Harris hip scores at the last follow up, were recorded and compared with those of 83 matched patients who underwent conventional manual positioning surgery.

Results

The TiRobot group had longer operation duration (83.3 ± 31.2 min vs 44.1 ± 14.8 min) and higher medical expenses (28,407.1 ± 7498.0 yuan vs 22,672.3 ± 4130.3 yuan) than the conventional group. The TiRobot group had significantly less intraoperative bleeding (11.3 ± 7.3 mL vs 51.6 ± 40.4 mL) and shorter hospital stay (8.6 ± 2.8 days vs 11.1 ± 3.41 days) than the conventional group. Screw parallelism (1.32° ± 1.85° vs 2.54° ± 2.99° on anteroposterior radiograph; 1.42° ± 2.25° vs 3.09° ± 3.63° on lateral radiograph) and distance between screws (58.44 ± 10.52 mm vs 39.69 ± 12.17 mm) were significantly improved. No significant difference was found between the two groups in terms of the use of fluoroscopy (40.1 ± 28.5 times vs 38.6 ± 21.0 times) and Harris hip scores at the last follow‐up (93.2 ± 10.3 points vs 88.4 ± 11.9 points). Two cannulated screws penetrated the femoral head during manual insertion in the conventional group but not in the TiRobot group. The rate of nonunion and necrosis of the femoral head in the TiRobot group was reduced compared with that in the conventional group (0 vs 7.2%; 6.0% vs 24.1%).

Conclusion

TiRobot‐assisted percutaneous cannulated screw fixation of femoral neck fractures is accurate and minimally invasive and helps in reducing late complications, particularly necrosis of the femoral head and nonunion of fractures.

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.

The Role of Intraoperative Navigation in Orthopaedic Surgery

An orthopaedic surgeon's knowledge of anatomical landmarks is crucial, but other modalities supplement this by providing guidance and feedback to a surgeon. Advances in imaging have enabled three-dimensional visualization of the surgical field and patient anatomy, whereas advances in computer technology have allowed for real-time tracking of instruments and implants. Together, these innovations have given rise to intraoperative navigation systems. The authors review these advances in intraoperative navigation across orthopaedic subspecialties, focusing on the most recent evidence on patient outcomes and complications, the associated learning curve, and the effects on operative time, radiation exposure, and cost. In spine surgery, navigated pedicle screw placement may increase accuracy and safety, especially valuable when treating complex deformities. Improved accuracy of pelvic and peri-articular tumor resection and percutaneous fixation of acetabular and femoral neck fractures has also been achieved using navigation. Early applications in arthroscopy have included surface-based registration for tunnel positioning for anterior cruciate ligament reconstruction and osteochondroplasty for femoro-acetabular impingement. Navigated arthroplasty techniques have addressed knee gap balancing and mechanical axis restoration as well as acetabular cup and glenoid baseplate positioning. Among these orthopaedic subspecialties, significant variation is found in the clinical relevance and dedication to research of navigation techniques.

Robot-assisted Percutaneous Cannulated Screw Fixation of Femoral Neck Fractures: Preliminary Clinical Results

OBJECTIVE

To assess the clinical efficacy of TiRobot-assisted percutaneous cannulated screw fixation in the treatment of femoral neck fractures.

METHODS

From September 2015 to July 2017, 26 patients with unilateral femoral neck fractures were treated with TiRobot-assisted percutaneous cannulated screw fixation. The femoral necks were fixed using three cannulated screws with robot assistance applying the following procedure: image acquisition, path planning, and needle and screw placement. The results of the treatment, including operation duration, frequency of fluoroscopy use, implant placement accuracy, intraoperative bleeding, total drilling, surgical complications, fracture healing time, fracture healing rate, and Harris scores at the last follow-up, were recorded and compared with 23 similar patients who underwent conventional manual positioning surgery.

RESULTS

A total of 147 cannulated screws were placed in all patients. The TiRobot group had shorter operation duration (62.6 ± 8.7 min vs 72.4 ± 10.3 min) and fracture healing time (5.1 ± 2.4 months vs 5.9 ± 2.8 months) than the conventional group (P > 0.05). The robot group had significantly less use of fluoroscopy (26.5 ± 7.4 times vs 51.3 ± 9.4 times), intraoperative bleeding (8.2 ± 5.3 mL vs 36.4 ± 12.5 mL), and total drilling (9.4 ± 4.2 times vs 18.3 ± 9.1 times) than the conventional group (all P < 0.05). The screw parallelism was significantly improved (24.0 ± 0.6 points vs 21.5 ± 1.2 points) and the neck-width coverage (72.0 ± 6.7 mm² vs 53.8 ± 10.4 mm² ) was significantly enlarged compared to the conventional group (P < 0.05). Only three guiding needles were used to penetrate the femoral head during manual insertion in the TiRobot group, which was significantly lower than that in the conventional group (3/78, 3.8% vs 9/69, 13.0%; P < 0.05). Other complications such as wound infection, vascular or nerve injury, screw loosening, and secondary screw displacement, did not occur in the two groups. There was no significant difference between the two groups in fracture healing rate (88.4% vs 82.6%) and Harris scores at the last follow up (88.2 ± 3.6 points vs 87.3 ± 4.7 points; P > 0.05).

CONCLUSION

TiRobot-assisted percutaneous cannulated screw fixation of femoral neck fractures is advantageous over conventional surgery with manual positioning due to easier manipulation, more accurate screw insertion, less invasion, and less radiation exposure, suggesting that it is a better method to stabilize femoral neck fractures.

Evaluation of a Bi-Planar Robot Navigation System for Insertion of Cannulated Screws in Femoral Neck Fractures

OBJECTIVE

To evaluate the bi-planar robot navigation system for insertion of cannulated screws in femoral neck fractures.

METHOD

Between January 2016 and December 2016, 60 patients with femoral neck fractures were separately treated using percutaneous cannulated screws assisted by the bi-planar robot navigation system (robot group) and conventional freehand surgery (freehand group). The fluoroscopy time, the number of drilling attempts, and the operation time were recorded during operations; the dispersion and parallelism of the cannulated screws on the posteroanterior and lateral images were measured after operations. Patients were followed up for 12-24 months and the Harris scores and the final results of the two groups were compared.

RESULTS

During bi-planar robot navigation system-assisted surgery, the fluoroscopy time for acquisition of images was 2.3 seconds on average, and the time for planning screws during the operation was 2.8 min on average. The average fluoroscopy time during the placement of the guide pin was 5.7 seconds and 14.14 seconds (P = 0.00), respectively. The average time of the placement of the cannulated screws was 12.7 min and 19.4 min (P = 0.00), respectively, in the robot group and the freehand group. In the robot group, only one guide pin was replaced during the operation, and the average number of adjustments for each guide pin was 2.39 in the freehand group. The screw parallelism and dispersion measured by postoperative imaging in the robot group were significantly superior to those in the freehand group. From postoperative CT it was evident that there were 5 cases of screws exiting the posterior cortex in both groups. During the follow-up phase, 1 case of femoral head necrosis and 5 cases of femoral neck shortening of more than 10 mm occurred in the robotic navigation group; 3 cases of femoral head necrosis, 1 case of fracture nonunion, and 2 cases of shortening of more than 10 mm occurred in the freehand group. At 18 months after surgery, the average Harris scores of the patients were 85.20 and 83.45, respectively, with no significant difference.

CONCLUSION

Using bi-planar robot navigation system-assisted placement of femoral neck cannulated screws can significantly reduce the time of intraoperative fluoroscopy, drilling attempts, and operation time. The placed screws are superior to the screws placed freehand in relation to parallelism and dispersion. However, it is still necessary for surgeons to have a good reduction of the femoral neck fracture before surgery and to be proficient in the operation of the robot navigation system. In summary, the bi-planar robot navigation system is an effective assistant instrument for surgery.

Accuracy analysis of computer-assisted surgery for femoral trochanteric fracture using a fluoroscopic navigation system: Stryker ADAPT® system

PURPOSE

ADAPT is a fluoroscopic computer-assisted surgery system which intraoperatively shows the distance from the tip of the screw to the surface of the femoral head, tip-to-head-surface distance (TSD), and the tip-apex distance (TAD) advocated by Baumgaertner et al. The study evaluated the accuracy of ADAPT.

PATIENTS AND METHODS

A total of 55 patients operated with ADAPT between August 2016 and March 2017 were included as subjects. TSD and TAD were measured postoperatively using computed tomography (CT) and X-rays. The intraclass correlation coefficient (ICC) was checked in advance. The error was defined as the difference between postoperative and intraoperative measurement values of ADAPT. Summary statistics, root mean square errors (RMSEs), and correlations were evaluated.

RESULTS

ICC was 0.94 [95% CI: 0.90-0.96] in TSD and 0.99 [95% CI: 0.98-0.99] in TAD. The error was -0.35 mm (-1.83 mm to 1.12 mm) in TSD and +0.63 mm (-5.65 mm to 4.59 mm) in TAD. RMSE was 0.63 mm in TSD and 1.53 mm in TAD. Pearson's correlation coefficient was 0.79 [95% CI: 0.66-0.87] in TSD and 0.83 [95% CI: 0.72-0.89] in TAD. There were no adverse events with ADAPT use.

CONCLUSION

ADAPT is highly accurate and useful in guiding surgeons in properly positioning the screws.

Use of fully threaded cannulated screws decreases femoral neck shortening after fixation of femoral neck fractures

BACKGROUND

Femoral neck fractures (FNF) are becoming increasingly common as population ages. Nondisplaced fractures are commonly treated by cancellous, parallel placed, partially threaded cannulated screws (PTS). This allows controlled fracture impaction. However, sliding implants can lead to femoral neck shortening (FNS) that has been shown to be correlated with reduced quality of life and impaired gait pattern. Recently, in our institution we have changed the fixation of FNF to fully threaded screws (FTS) with or without an additional partially threaded screw in order to minimize this phenomenon. The aim of this study was to compare the FNS in patients treated with FTS as compared with our historical controls treated with PTS.

PATIENTS AND METHODS

Between 2014 and 2016, 38 patients with FNF were treated with FTS. Out of the 38, 24 were available for radiographic follow-up. 41 patients treated previously with PTS were available as a control group. Radiographic analysis was performed to assess the FNF in three vectors: Horizontal (X), Vertical (Y) and overall (Z) according to the neck-shaft angle.

RESULTS

Time for admission to surgery was longer in the PTS group (p = 0.04). Patient demographics and major complication rates were similar in the two patient groups. Average FNS in the X axis was significantly smaller in the FTS group than in the PTS group (2.8 ± 3.6 vs 7.6 ± 4.2 mm, p < 0.01) as well as the Y axis (1.2 ± 2.6 vs 4.9 ± 4.2 mm, p < 0.01) and thus also decreased overall Z shortening (2.3 ± 3.5 vs 6.23 ± 4.5 mm, p < 0.01). There was a tendency towards a more valgus reduction in the PTS (137° vs 134°, p = 0.08). There was a significantly smaller number of FTS patients with moderate (5-10 mm) or severe (> 10 mm) FNS. Screw pull-out > 5 mm occurred in 17/41 patients in the PTS but none in the FTS group (p < 0.01).

CONCLUSION

This study proves that use of FTS improves the radiographic results following FNF fixation using cannulated screws.

Computer-assisted navigation for intramedullary nail fixation of intertrochanteric femur fractures: A randomized, controlled trial

INTRODUCTION

Lag screw cutout is one of the most commonly reported complications following intramedullary nail fixation of intertrochanteric femur fractures. However, its occurrence can be minimized by a well-positioned implant, with a short Tip-to-Apex Distance (TAD). Computer-assisted navigation systems provide surgeons with the ability to track screw placement in real-time. This could allow for improved lag screw placement and potentially reduce radiation exposure to the patient and surgeon.

METHODS

Between Oct 2014 and Jan 2016, patients with intertrochanteric femur fractures being treated with intramedullary nail fixation by one of three fellowship-trained orthopaedic traumatologists were enrolled. Inclusion criteria were low-energy mechanism of injury and fracture class 31-A1/A2. Open fractures and patients with multiple injuries to the lower extremity were excluded. Patients were randomly assigned to computer-assisted navigation or a conventional fluoroscopic technique for lag screw placement. The primary outcomes were TAD, measured by postoperative anteroposterior and lateral x-rays by an independent reviewer, and radiation exposure measured in seconds of fluoroscopy time. Surgical time was also recorded.

RESULTS

50 patients were randomized, 26 to the computer-assisted navigation group and 24 to the control group. The mean manually-measured TAD in the computer-assisted navigation group was 14.1mm±3.2 and in the control group was 14.9mm±3.0 (p=0.394). There was no difference between groups in total radiation time (navigation: 58.8 s±23.6, control: 56.5 s±28.5, p=0.337) or radiation time during lag screw placement (navigation: 19.4 s±8.8, control: 18.8 s±8.0, p=0.522). The surgical time was significantly longer in the computer-assisted navigation group with a mean surgical time of 45.8min±9.8 compared to 38.4min±9.3 in the control group (p=0.009).

CONCLUSIONS

Computer-assisted navigation consistently produced excellent TADs, however it was not significantly better than conventional methods when done by fellowship-trained orthopaedic traumatologists. Surgeons with a lower volume trauma practice could potentially benefit from computer-assisted navigation to obtain better TAD.

Error range in proximal femoral osteotomy using computer tomography-based navigation

PURPOSE  : The purpose of this preliminary study was to determine the error range compared with preoperative plans in proximal femoral osteotomy conducted using a computed tomography (CT)-based navigation system. METHODS  : Four patients (four hips) underwent transtrochanteric rotational osteotomy (TRO), and three patients (four hips) underwent curved varus osteotomy (CVO) using CT-based navigation. Volume registration of pre- and postoperative CT was performed for error assessment. RESULTS  : In TRO, the mean osteotomy angle error was [Formula: see text] (range [Formula: see text]) in the valgus direction and [Formula: see text] (range [Formula: see text]) in the retroversion direction. The mean osteotomy position error, with the femoral head side as positive, was -0.4 mm (range -1.4 to 0 mm). The bone fragment rotational movement error was [Formula: see text] (range [Formula: see text]). In CVO, the mean osteotomy position error, with the femoral head side as positive, was -0.2 mm (range -2.0 to 1.7 mm) at the level of the lesser trochanter and 0.8 mm (range 0-3.2 mm) at the level of the greater trochanter. Bone fragment varus accuracy was [Formula: see text] (range [Formula: see text]). CONCLUSIONS  : In proximal femoral osteotomy using CT-based navigation, the angle error of osteotomy was within [Formula: see text] and the positional error was within 4 mm. The rotational movement error of the proximal fragment was within [Formula: see text]. These margins of error should be considered in preoperative planning. To improve surgical accuracy, it would be necessary to develop a computer-assisted device which can track the osteotomized fragment.

[Clinical application of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures]

Objective

To investigate the clinical efficacy of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures.

Methods

A retrospective analysis was made on the clinical data of 20 femoral neck fracture patients treated by computer-assisted cannulated screw internal fixation system based on error correction method between January 2014 and October 2015 (trial group), and 36 femoral neck fracture patients undergoing traditional manual surgery with closed reduction by cannulated screw fixation in the same period (the control group). There was no significant difference in gender, age, injury cause, side of fracture, types of fracture, and time from injury to operation between 2 groups ( P>0.05). The operation time, intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion, fracture healing time, fracture healing rate, and Harris hip score were compared between 2 groups.

Results

All incisions healed by first intention after operation, and no complication of blood vessel and nerve injury occurred. The operation time of trial group was significantly longer than that of control group ( t=2.290, P=0.026), however, the intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion of trial group were significantly less than those of control group ( t=-10.650, P=0.000; t=18.320, P=0.000; t=-16.625, P=0.000). All patients were followed up 12-18 months (mean, 14.7 months). X-ray films showed that fracture healing was obtained in 2 groups, showing no significant difference in fracture healing time between 2 groups ( t=0.208, P=0.836). No complication of ischemic necrosis of femoral head occurred during follow-up period. At last follow-up, the Harris hip score was 87.05±3.12 in trial group and was 86.78±2.83 in control group, showing no significant difference ( t=0.333, P=0.741).

Conclusion

Computer-assisted cannulated screw internal fixation surgery based on error correction method for femoral neck fractures is better than traditional manual surgery in decreasing intraoperative radiation and surgical trauma during operation.

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.

Improved lag screw positioning in the treatment of proximal femur fractures using a novel computer assisted surgery method: a cadaveric study

Background

The importance of the tip-apex distance (TAD) to predict the cut-out risk of fixed angle hip implants has been widely discussed in the scientific literature. Intra-operative determination of TAD is difficult and can be hampered by image quality, body habitus, and image projection. The purpose of this paper is to evaluate, through a cadaveric study, a novel computer assisted surgery system (ADAPT), which is intended for intraoperative optimisation of lag screw positioning during antegrade femoral nailing. A 3D measure for optimal lag screw position, the tip-to-head-surface distance (TSD), is introduced.

Methods

45 intra-medullary hip screw procedures were performed by experienced and less experienced surgeons in a cadaveric test series: in 23 surgeries the ADAPT system was used, and in 22 it was not used. The position of the lag screw within the femoral head and neck was evaluated using post-operative CT scans. TAD, TSD, fluoroscopy as well as procedure time and variability were assessed.

Results

The use of the ADAPT system increased accuracy in TSD values (i.e. smaller variability around the target value) for both groups of surgeons (interquartile range (IQR) of experienced surgeons: 4.10 mm (Conventional) vs. 1.35 mm (ADAPT) (p = 0.004)/IQR of less experienced surgeons: 3.60 mm (Conventional) vs. 0.85 mm (ADAPT) (p = 0.002)). The accuracy gain in TAD values did not prove to be significant in the grouped analysis (p = 0.269 for experienced surgeons; p = 0.066 for less experienced surgeons); however, the overall analysis showed a significant increase in accuracy (IQR: 4.50 mm (Conventional) vs. 2.00 mm (ADAPT) (p = 0.042)). The fluoroscopy time was significantly decreased by the use of the ADAPT system with a median value of 29.00 seconds (Conventional) vs. 17.00 seconds (ADAPT) for the less experienced surgeons (p = 0.046). There was no statistically significant impact on the procedure time (p = 0.739).

Conclusions

The ADAPT system improved the position of the lag screw within the femoral head, regardless of the surgeon’s level of clinical experience, and at the same time decreased overall fluoroscopy usage. These positive effects are achieved without increasing procedure time.

Self-designed femoral neck guide pin locator for femoral neck fractures

Closed reduction and fixation with 3 cannulated screws is a widely accepted surgery for the treatment of femoral neck fractures. However, how to obtain optimal screw placement remains unclear. In the current study, the authors designed a guide pin positioning system for femoral neck fracture cannulated screw fixation and examined its application value by comparing it with freehand guide needle positioning and with general guide pin locator positioning provided by equipment manufacturers. The screw reset rate, screw parallelism, triangle area formed by the link line of the entry point of 3 guide pins, and maximum vertical load bearing of the femoral neck after internal fixation were recorded. As expected, the triangle area was largest in the self-designed positioning group, followed by the general positioning group and the freehand positioning group. The difference among the 3 groups was statistically significant (P<.05). Anteroposterior and lateral radiographs showed that the screws were more parallel in the self-designed positioning group and general positioning group compared with the freehand positioning group (P<.05). The screw reset rate in the self-designed positioning group was significantly lower than that in the general positioning group and the freehand positioning group (P<.05). Maximum bearing load among the 3 groups was equivalent, showing no statistically significant difference (P>.05). The authors’ self-designed guide pin positioning system has the potential to accurately insert cannulated screws in femoral neck fractures and may reduce bone loss and unnecessary radiation.

Computer-assisted navigation in orthopedic surgery

Computer-assisted navigation has a role in some orthopedic procedures. It allows the surgeons to obtain real-time feedback and offers the potential to decrease intra-operative errors and optimize the surgical result. Computer-assisted navigation systems can be active or passive. Active navigation systems can either perform surgical tasks or prohibit the surgeon from moving past a predefined zone. Passive navigation systems provide intraoperative information, which is displayed on a monitor, but the surgeon is free to make any decisions he or she deems necessary. This article reviews the available types of computer-assisted navigation, summarizes the clinical applications and reviews the results of related series using navigation, and informs surgeons of the disadvantages and pitfalls of computer-assisted navigation in orthopedic surgery.

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.

Accuracy study of new computer-assisted orthopedic surgery software

PURPOSE

The new computerized system is based on image analysis and designed to aid in orthopedic surgeries by virtual trajectory of the guide wire, intra-operative planning and various measurements. Validation of the accuracy and safety of any computer-aided surgery system is essential before implementing it clinically. We examined the accuracy of guide-wire length and angle measurements and fusion of multiple adjacent images (panoramic view image, PVI(®)) of the new software.

METHODS

This is a 2-part study. Part I: twenty guide wires were drilled to various depths in a synthetic femur model and the results obtained by the software measurements were compared with manual measurements by a caliper and a depth gauge. Part II: a sawbone femur shaft was osteotomized and various inclinations of > 10° to the varus or valgus angles were tested. The manually obtained measurements of angles and lengths were compared to the new computerized system software PVI.

RESULTS

There was a significant positive linear correlation between all groups of the computerized length and the control measurements (r>0.983, p<0.01). There was no significant difference among different distances, angles or positions from the image intensifier. There was a significant positive linear correlation between the angle and length measurement on the PVI and the control measurement (r>0.993, p<0.01).

CONCLUSIONS

The new computerized software has high reliability in performing measurements of length using an aiming, positioning and referring device intra-operatively.

A novel method of image-based navigation in fracture surgery

The treatment of three- and four-part fractures of the humeral head is still controversially discussed. Some advocate primary arthroplasty while the results of primary fixation seem to be superior if no necrosis of the humeral head develops. Today navigation is used in orthopaedic surgery mainly for interventions on the spine, the pelvis and arthroplasty. In trauma surgery it is still rarely used and some technical problems need to be overcome. We report on a case of a three part fracture of the humeral head with mini-open reduction and fixation with image-based guided headless compression screws. For the fixation each screw was placed on the first trial, total radiation time was 60 s. At 12-month follow-up assessment radiographs showed a consolidated fracture, no loosening of the screws and a good glenohumeral articulation. The patient had free function of the shoulder and no pain, the constant score was 98 and the dash score 0. There is no evidence of a necrosis of the humeral head. The literature focuses on shoulder arthroplasty. There are no reports on the use of image-based guidance in shoulder traumatology so far. In conclusion, the described technique allows an accurate fixation of the humeral head fracture as the guidance system (Surgix) ensures the "first try first hit" screw positioning. The new system was integrated in the workflow and supports the surgeon as an aiming device. The role of navigation system in enhancing minimally invasive surgery of the shoulder should be further explored.

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.

Proximal femoral locking plate with cannulated screws for the treatment of femoral neck fractures

The purpose of this study was to evaluate the efficacy and safety of the proximal femoral locking plate with cannulated screws for the treatment of femoral neck fractures. A prospective study was performed in 41 patients with femoral neck fractures treated with a proximal femoral locking plate with cannulated screws between January 2005 and December 2008. Twenty-five men and 16 women had a mean age of 47 years (range, 21-65 years). The time from injury to surgery ranged from 2 hours to 7 days. Three patients had a Garden type I fracture, 9 a type II, 18 a type III and 11 a type IV. Operative time, intraoperative blood loss, fracture healing time, Harris Hip Score for hip function, and complications were recorded to evaluate treatment effects.Mean operative time was 63.6 minutes (range, 40-90 minutes), with mean intraoperative blood loss of 84.2 mL (range, 50-200 mL). Mean time to union was 15.5 weeks (range, 12-36 weeks). Two patients (Garden type III and type IV) did not achieve union, and 4 patients (1 Garden type III and 3 type IV) had avascular necrosis of the femoral head. In patients with nonunion, 1 (Garden type III) underwent intertrochanteric osteotomy, and the other underwent total hip replacement (THR). In patients with avascular necrosis, 2 required THR and the others (1 Garden type III) required no further surgery. Twenty-six (63%) patients had excellent results, 8 (20%) had good results, 3 (7%) had moderate results, and 4 (10%) had poor results. These findings suggest that the proximal femoral locking plate with cannulated screws for the treatment of femoral neck fractures is effective and results in fewer complications, especially for Garden type I, II, and III fractures.

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.

Computer-assisted trauma surgery

Computer-assisted orthopaedic surgery (CAOS) is performed by digitizing the patient's anatomy, combining the images in a computerized system, and integrating the surgical instruments into the digitized image background. This allows the surgeon to navigate the surgical instruments and the bone in an improved, virtual visual environment. CAOS in traumatology is performed with images obtained by fluoroscopy, CT, or three-dimensional fluoroscopy. CAOS is used in basic trauma procedures for preoperative planning, fracture reduction, intramedullary nailing, percutaneous screw or plate fixation, and hardware or shrapnel removal. Potential benefits of CAOS include minimal invasiveness, increased accuracy, and decreased radiation exposure. Limitations include a significant learning curve, increased surgical time, requirements for special setup and equipment handling in the operating room, specialized technical support, and cost. Current evidence shows no advantage with CAOS in trauma cases compared with conventional methods. Prospective randomized trials and clinical outcomes are lacking.

The accuracy and precision of computer assisted surgery in the assessment of frontal plane deviations of the lower extremity: a femoral fracture model

OBJECTIVES

Mechanical axis deviation of the lower extremity as a result of malreduction or malunion of fractures plays an important role in the development of arthritis. Therefore it is crucial to restore the limb alignment as accurate as possible. The purpose of this study was to evaluate the accuracy and precision of navigation in assessing isolated frontal plane (varus/valgus) deviations of the lower limb in a simulated fracture model of the femur.

MATERIALS AND METHODS

Three fracture models with ten specimens in each were created in femoral synthetic composite bones to simulate a subtrochanteric (AO/OTA 31-A1), mid-diaphyseal (AO/OTA 32-A3), and supracondylar (AO/OTA 33-A1) femur fracture. Each specimen was mounted on a custom holding device and registered with the navigation system. Eight custom-made aluminum wedges of varying angles (5 degrees -26 degrees ) were used to create varus/valgus angulations at the fracture site. After wedge placement, the frontal plane deformity was recorded and registered by the navigation system. The means and standard deviations for each navigated wedge angle were calculated and compared to the actual wedge angle using a one sample t test. A single factor ANOVA test was subsequently performed to see if the differences between the navigated mean angles in each fracture group were statistically significant. The level of significance was defined as P < 0.05.

RESULTS

None of the navigated mean angles were found to be significantly different from the actual wedge angles (P = 0.05-1.00). More specifically, the differences between the navigated mean angles and the actual wedge angles ranged from 0 degrees to 0.7 degrees . Furthermore, the differences between the navigated mean angles in each angle group were found to be statistically insignificant (P = 0.53-0.99).

CONCLUSION

The high accuracy and precision of navigation systems in determining frontal plane deformities of long bones can make them an invaluable tool for the exact reduction and realignment of lower extremity fractures.

Computer-assisted surgery for subtalar arthrodesis. A study in cadavers

BACKGROUND

Despite considerable recent interest in computer navigation for orthopaedic surgery, few investigations of computer-assisted surgery for foot and ankle operations have been reported. The purpose of the present study was to compare subtalar arthrodesis with and without computer navigation in a cadaver model.

METHODS

Subtalar arthrodesis was performed on thirty-six matched-pair cadaver lower extremities with intact soft tissues, with an attempt being made to orient two screws in the optimal configuration based on unpublished data from a preceding biomechanical study. Each matched pair was randomly assigned either to a group of surgeons who were experienced in subtalar arthrodesis or to a group of inexperienced operators. Neither surgical group was experienced in computer-assisted surgery. We compared optimal first-pass guidewire placement, fluoroscopic time, total operative time, screw placement accuracy, and adverse screw placement events between conventional (fluoroscopically guided) and computer-assisted subtalar arthrodesis.

RESULTS

The number of passes needed to achieve optimal guidewire placement decreased with the use of computer assistance for both experienced surgeons and inexperienced operators (p < 0.001), with ideal placement occurring on the first attempt in 95% of the procedures performed with use of computer assistance. While the experienced surgeons required less time and fewer guidewire passes during conventional subtalar arthrodesis than the inexperienced operators did (p < 0.001), both groups used less fluoroscopy with computer assistance (p < 0.001). There was no significant difference in operative time between the two techniques when performed by the inexperienced operators, yet the total procedure time doubled for the experienced surgeons when the procedure was performed with use of computer assistance (p < 0.001). There was no significant difference between experienced surgeons and inexperienced operators or between conventional and computer-assisted subtalar arthrodesis with respect to adverse screw placement events or the ability to accurately place both screws.

CONCLUSIONS

Computer-assisted subtalar arthrodesis resulted in screw placement accuracy that was equivalent to that of conventional (fluoroscopically guided) subtalar arthrodesis while decreasing the number of suboptimal guidewire passes and fluoroscopic time. The computer-assisted surgery technique increased the operative time for surgeons who were more experienced in conventional subtalar arthrodesis, but there was no difference in operative time for the group of operators who were inexperienced in subtalar arthrodesis.

[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.

Fracture-table-mounted versus bone-mounted dynamic reference frame tracking accuracy using computer-assisted orthopaedic surgery--a comparative study

OBJECTIVE

Fluoroscopy-based computerized navigation systems enable accurate implant placement while reducing radiation exposure. The navigation process normally requires the attachment of a dynamic reference frame (DRF) to a bone, causing additional surgical trauma. The aim of this study was to compare the accuracy of navigation with the DRF either attached to the bone or mounted on the fracture table.

METHODS

We conducted a prospective study on 10 consecutive patients who underwent operative fixation of femoral neck fractures with cannulated screws using computerized navigation. After insertion of the three guide wires, the DRF was moved from the patient's bone to the fracture table. For each screw, angular and translational deviations of the navigated images as compared to the conventional fluoroscopic images were analyzed.

RESULTS

The accuracy of navigated Kirschner wire placement was similar with both techniques, resulting in an average translational error of less than 2 mm in both groups and around 1 degrees in angulation error--both of these accuracy measurements are acceptable and sufficient for the insertion of cannulated screws into the femoral head.

CONCLUSION

Our study suggests that attaching the DRF to a fracture table during navigated femoral neck fixation allows for acceptable accuracy with the possible added benefit of reducing patient morbidity.

Surface-data-based haptic rendering for simulation of surgery of closed reduction and internal fixation

This paper presents a surface-data-based haptic rendering method for simulation of surgery of closed reduction and internal fixation (CRIF). Volumetric data is often employed in the simulation of bone surgery because the volume rendering can easily handle information such as density and rigidity of each voxel. However, it is difficult to implement real-time graphics and haptic rendering because of the large computational workload. Therefore, we propose a surface-data-based haptic rendering method for real-time rendering. Mechanical properties and graphics of the inner part of the bone should be modeled in addition to the surface data to simulate drilling into the bone. An algorithm is developed to construct the surface of the drilled hole. This method allows the user of the simulation to feel the varying forces according to the drilled depth.