Fluoroscopically assisted computer navigation enables accurate percutaneous screw placement for pelvic and acetabular fracture fixation

Preoperative planning technique for anterior pelvis percutaneous intramedullary screw fixation

Useful techniques have been previously described for the planning of safe transsacral-transiliac screws, but to our knowledge, no straightforward technique has been described for anterior pelvic percutaneous fixation. As this method of anterior ring fixation has demonstrated biomechanical and clinical benefits, we propose a preoperative planning technique for determining the corridor characteristics of the patient's superior pubic ramus/anterior column for fracture fixation with percutaneous intramedullary screws. This technique helps the surgeon assess what diameter of solid or cannulated screw the corridor allows and predict the length of screw needed.

Enhanced accuracy and reduced complications: robot-assisted navigation for retrograde intramedullary nailing in distal femoral fractures

PURPOSE

This research investigates the benefits of robot-assisted navigation systems in retrograde intramedullary nailing for distal femoral fractures and contrasts their outcomes with conventional surgical methods. This is a retrospective clinical study designed to compare the outcomes of these two approaches.

METHODS

This study included 56 distal femoral fracture patients treated between February 2020 and May 2023. Among them, 28 patients underwent robot-assisted retrograde intramedullary nailing (robot group), while 28 received conventional retrograde intramedullary nailing (traditional group). Surgical duration, intraoperative fluoroscopy frequency, number of guidewire insertions into the femoral medullary cavity, and intraoperative blood loss were recorded. Healing progress and fixation stability status were observed, and postoperative articular function was assessed using Neer's scoring system at a one year follow-up.

RESULTS

Baseline characteristics were comparable between the two groups, showing no statistically significant differences.The robot group demonstrated shorter operative time, fewer guidewire placements, reduced intraoperative hemorrhage and incision size compared to the traditional group (P < 0.05). While the Neer's score for postoperative joint function showed a higher excellent-to-good rate in the robot group, no significant difference was observed between the group (P > 0.05).

CONCLUSION

Compared with traditional surgical methods, robot-assisted retrograde intramedullary fixation for fractures of the distal femur offers advantages of being minimally invasive, more precise, requiring shorter operative times, and resulting in reduced blood loss, fluoroscopy exposure, and guidewire insertion attempts. These benefits may contribute to a reduction in postoperative complications.

TiRobot-assisted versus freehand femoral neck system placement in the treatment of femoral neck fractures: a systematic review and meta-analysis

The purpose of this study is to assess the safety and effectiveness of TiRobot-assisted treatment for femoral neck fractures, in comparison to traditional freehand treatment methods. Throughout the research process, we conducted an extensive literature search across numerous databases, including PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), CQVIP, and Wanfang. Based on the literature screening criteria, we selected six studies, encompassing 358 cases of femoral neck fracture patients, for this meta-analysis. The study evaluated the effectiveness of TiRobot-assisted versus freehand placement of the Femoral Neck System (FNS). The results indicate that the TiRobot-assisted group demonstrated significant advantages in several surgical parameters. Specifically, the robot-assisted group showed superior outcomes regarding the frequency of guide pin insertion, frequency of X-ray fluoroscopy, operative time, invasive fixation time, intraoperative blood loss and incision length (MD < 0, p < 0.05). Furthermore, there was a significant difference in the Harris score, between the TiRobot-assisted group and the traditional freehand group (MD > 0, p < 0.05). However, the two groups had no significant differences concerning postoperative complications, fracture healing time, and fracture healing rate (p > 0.05). In conclusion, the comprehensive analysis suggests that the TiRobot-assisted technique has distinct advantages over the traditional freehand technique in treating femoral neck fractures. TiRobot-assisted technology, owing to its enhanced safety and efficacy, minimizes surgical trauma and expedites postoperative recovery.

A systematic review and meta-analysis comparing robotic-assisted percutaneous screw fixation and conventional surgical techniques for acetabular fractures

The objective of this comprehensive review and meta-analysis was to evaluate the effectiveness of robot-aided percutaneous screw fixation versus traditional surgical techniques in managing acetabular fractures. We plan to carry out an exhaustive exploration of certain databases (PubMed, CNKI, Embase, and Cochrane Library) to find studies that have been published since the beginning of these databases until August 2024, focusing on patients with acetabular fractures. These studies will compare the efficacy of robot-assisted percutaneous screw fixation with conventional surgical methods. Both English and Chinese literature will be included. We will adhere strictly to the predefined inclusion and exclusion criteria, with a focus on randomized controlled trials and cohort studies. Review Manager 5.4.1 will be utilized for the execution of data analysis. The ROBINS-I instrument will be used to evaluate the bias risk in Not-RCTs. The final analysis included 6 retrospective cohort studies, encompassing a total of 168 patients, with 83 undergoing robot-assisted percutaneous screw fixation and 85 receiving conventional surgery. The results indicated that patients treated with robot-assisted percutaneous screw fixation had shorter OT, fewer intraoperative fluoroscopy instances, and fewer adjustments of guide pins compared to those receiving conventional surgery. However, no significant differences were observed between the two treatment methods in terms of Modified Postel Merle D'Aubigne scores and EBL. The use of robots in percutaneous screw fixation has been demonstrated to be a secure and efficient method for managing acetabular fractures. Compared to conventional ORIF or free-hand screw fixation, this robotic-assisted technique offers significant advantages, including reduced operation time, lower IFF, and fewer guide wire adjustments.

Application of robot navigation system for insertion of femoral neck system in the treatment of femoral neck fracture

PURPOSE

To evaluate the short-term clinical efficacy and advantages of surgery robot positioning system for insertion of Femoral Neck System (FNS) in the treatment of femoral neck fractures.

METHODS

The clinical data of 52 patients with Femoral neck fracture (FNF) who had been treated with FNS between June 2020 and September 2021 were retrospectively analyzed. Among them, 26 patients were treated with traditional FNS (control group), while 26 additional patients were treated with FNS assisted by an orthopaedic robot positioning system (study group). The operation duration, frequency of key-guide needle placement, intraoperative blood loss, incision length, fracture healing rate, fracture healing time, and the Harris scores at the last follow-up were calculated and compared between the 2 groups.

RESULTS

The study group had shorter operation duration, fewer numbers of placing the key-guide needle, less intraoperative blood loss, and smaller surgical incisions than the control group (all, P < 0.05). There was no significant difference in the rate of fracture healing rate between the 2 groups (P = 0.47), while the fracture healing duration of the study group was shorter than that of the control group (P = 0.03). At the last follow-up, compared with the control group, the Harris score and the number of excellent and good ratings were significantly higher in the study group (all, P < 0.05).

CONCLUSIONS

Using orthopaedic surgery robot positioning system-assisted FNS in the treatment of FNFs can effectively improve the efficiency of surgery, shorten operation time, and reduce the number of placing the key-guide needle, intraoperative blood loss, and operative trauma. Simultaneously, it shortens the duration of fracture healing and improves the recovery of hip function.

A New Technology Using Mixed Reality Surgical Navigation with the Unlocking Closed Reduction Technique Frame to Assist Pelvic Fracture Reduction and Fixation: Technical Note

BACKGROUND

Pelvic ring disruption (PRD) is a serious trauma associated with high mortality and disability rates. Poor reduction can lead to complications such as pelvic deformity and delayed fracture healing. Here, we introduce a new technology using mixed reality surgical navigation (MRSN) with an unlocking closed reduction technique (UCRT) frame to assist pelvic fracture reduction and fixation.

METHODS

Thirty patients with PRD were enrolled in this study. All of the patients underwent preoperative CT scans, with the pelvis and tracker segmented into three-dimensional models. Under MRSN guidance, auxiliary reduction screws were inserted to grasp the pelvic bone. An ideal trajectory for closed reduction was planned, and suitable CS screws were used for stable fixation after good reduction. Operation time, fluoroscopy frequency, and both Matta and Majeed scores were analyzed.

RESULTS

The mean follow-up period was 10.8 months (7.5, 12.25 months) (range 6-24 months). The average duration of operation was 212.5 min (187.5, 272.8 min) (range 133-562 min), and the average reduction time was 23.0 min (15.0, 42.5 min) (range 10-70). The average fluoroscopy frequency was 34.0 times (31.5, 52.5 times) (range 23-68 times). One hundred and fifty screws were successfully inserted on the first attempt. All the fractures healed well with no complications. Excellent reduction quality (Matta score ≤4 mm) was achieved in 29/30 cases, and good reduction quality (Matta score between 4 and 10 mm) was achieved in 1/30 cases. All patients achieved bone healing after an average of 4.0 months (3.5, 5.9 months) (range 3-6), as well as good function recovery with an average Majeed score of 91.0 (87.8, 95.0) (range 71-100).

CONCLUSION

The MRSN technique described improved reduction accuracy and radiation exposure without considerable extension of operation time.

A standard canulated screw may not fit up to 1/3 of the patients treated percutaneously for anterior column acetabular fractures-A pilot study

A proper evaluation of the narrowings and length of the anterior acetabular column would offer better predictability and precision for implant insertion in the case of an acetabular fracture.

OBJECTIVE

To determine the diameter and length of the safety corridor of the anterior column of the acetabulum in patients with available pelvic computed tomography (CT), analyze the obtained measurements against those of a standard 6.5-mm implant, and verify possible sex differences regarding these measurements. A secondary aim was to develop a method for measurement of the anterior column of the acetabulum based on CT images.

MATERIALS AND METHODS

In 200 CT scans of hemipelvises we measured the diameter of two areas of narrowing and the length of the safety corridor of the anterior column. The images were submitted to multiplanar reformatting adjusted to a plane orthogonal to the bone corridor, drawn at the level of the superior pubic ramus.

RESULTS

Measurement #1 had a mean value of 8.12 (2.27) mm in the overall sample and median values of 9.03 (7.76-10.48) mm in men and 6.77 (5.44-7.19) mm in women. Measurement #2 had a mean value of 7.29 (2.19) mm and median values of 8.23 (7.18-9.82) mm in men and 5.9 (4.65-7.19) mm in women. Measurement #3 had a mean value of 109.53 (13.66) mm in the overall sample and median values of 117.17 (112.9-122.9) mm in men and 100.91 (90.95-111.17) mm in women (p<0.001 all three measurements). Measurement #1 was smaller than 6.5 mm in 22.5% of the patients (of whom 90% were women). Measurement #2 was smaller than 6.5 mm in 35% of the patients (of whom 80% were women).

CONCLUSIONS

This study proposed an anatomic evaluation of the anterior column of the acetabulum using conventional CT images The areas of narrowing in the anterior column had an average of 8.12 mm at the level of the pubic tubercle and 7.29 mm at the level of the acetabular fossa. The mean length of the safety corridor was 109.53 mm. In 35% of the cases, a 6.5 mm percutaneous screw would have violated the cortical bone of the safety corridor.

A multi-view interactive virtual-physical registration method for mixed reality based surgical navigation in pelvic and acetabular fracture fixation

PURPOSE

The treatment of pelvic and acetabular fractures remains technically demanding, and traditional surgical navigation systems suffer from the hand-eye mis-coordination. This paper describes a multi-view interactive virtual-physical registration method to enhance the surgeon's depth perception and a mixed reality (MR)-based surgical navigation system for pelvic and acetabular fracture fixation.

METHODS

First, the pelvic structure is reconstructed by segmentation in a preoperative CT scan, and an insertion path for the percutaneous LC-II screw is computed. A custom hand-held registration cube is used for virtual-physical registration. Three strategies are proposed to improve the surgeon's depth perception: vertices alignment, tremble compensation and multi-view averaging. During navigation, distance and angular deviation visual cues are updated to help the surgeon with the guide wire insertion. The methods have been integrated into an MR module in a surgical navigation system.

RESULTS

Phantom experiments were conducted. Ablation experimental results demonstrated the effectiveness of each strategy in the virtual-physical registration method. The proposed method achieved the best accuracy in comparison with related works. For percutaneous guide wire placement, our system achieved a mean bony entry point error of 2.76 ± 1.31 mm, a mean bony exit point error of 4.13 ± 1.74 mm, and a mean angular deviation of 3.04 ± 1.22°.

CONCLUSIONS

The proposed method can improve the virtual-physical fusion accuracy. The developed MR-based surgical navigation system has clinical application potential. Cadaver and clinical experiments will be conducted in future.

[Imaging examination procedures, navigation and minimally invasive procedures in acetabular surgery]

Acetabular fractures still pose a special challenge even today. Considering the increasing case numbers, especially in the geriatric patient group, modern imaging examination procedures represent an essential pillar of the diagnostics. Especially in this vulnerable patient group, minimally invasive methods are necessary, which can be guaranteed by intraoperative navigation; however, the choice of surgical access and implants is also made based on the existing morphological characteristics of fractures, which highlights the importance of an imaging modality that is as detailed as possible. Last but not least, new developments concerning the surgical treatment of these injuries are also based on this. This article summarizes the current state of the techniques and the available literature.

Current status of robot-assisted surgery in the clinical application of trauma orthopedics in China: A systematic review

Background and Aims

To elaborate on the development and characteristics of trauma orthopedic robots and their real curative effect in a clinical application through the collection and analysis of relevant literature and reported clinical results.

Method

We conducted the Embase, ScienceDirect, Pubmed, Medline, Wanfang, CNKI, and VIP search of the literature on robotic-assisted surgery in trauma orthopedics in China. We combined search terms with "robotic surgery/artificial intelligence surgery/navigation surgery," "trauma/trauma orthopedics," and "China/Chinese." The exclusion criteria were: (1) articles in languages other than English or Chinese, (2) articles focused on other topics other than robotic-assisted surgery in trauma orthopedics of China, (3) article types were not clinical studies (reviews, basic research, etc.), and (4) articles were not included in the Chinese core journals or science citation index. Authors, type of surgery, robot type, and clinical research results were recorded and analyzed.

Results

There were three categories of surgical robots in the clinical application of trauma orthopedics (TiRobot, electromagnetic navigation surgical robots, and small medical robots developed by Beijing Jishuitan Hospital). In terms of blood loss, the fluoroscopy time, and fluoroscopy frequency, most studies found that the robot group was significantly better than the traditional group.

Conclusions

Robot-assisted surgery has obvious advantages in accuracy, stability, and reducing intraoperative radiation exposure, but there is no final conclusion about functional recovery.

[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.

Starr frame-assisted and minimally invasive internal fixation for pelvic fractures: Simultaneous anterior and posterior ring stability

OBJECTIVE

We aimed to investigate the surgical techniques, efficacy, and safety of Starr frame-assisted and minimally invasive internal fixation for simultaneous anterior and posterior ring stability in pelvic fractures.

METHODS

The clinical data of 22 patients with anterior and posterior pelvic ring injuries who underwent Starr frame-assisted and minimally invasive internal fixation were retrospectively collected. The anterior pelvic ring was fixed with an anterior subcutaneous internal fixator (INFIX), and the posterior pelvic ring was fixed with sacroiliac screws. The operative time, intraoperative blood loss, fluoroscopy times, number of assistants, complications, and weight-bearing time were analyzed. The Matta score was used to evaluate the fracture reduction. The Majeed score was used to evaluate clinical efficacy, and Gibbon's classification was used to estimate the occurrence of sacral nerve injury.

RESULTS

All 22 patients were treated with sacroiliac screws for posterior ring injuries, including 12 cases with single sacroiliac screws, nine with two sacroiliac screws, and one with three sacroiliac screws. INFIX was used for all anterior ring fixation, including two screws in seven cases, three screws in 13 cases, and four screws in two cases. The fracture reduction quality was excellent in 15 cases, good in four cases, and moderate in three cases by Matta scores. All patients were followed up for 6-20 (12.5 ± 5.7) months. Callus-formation time based on postoperative X-ray was 3-8 (4.3 ± 1.2) weeks. Weight-bearing time was 3-12 (6.3 ± 2.8) weeks after surgery. At the last follow-up, 15 patients were evaluated as excellent, five as good, and two as fair according to the Majeed score. Gibbons' classification showed that one of the three patients with sacral nerve injury recovered completely and two did not recover. Complications occurred in six patients, including one with internal fixation loosening, two with anterolateral thigh paresthesia, one with malunion, one with nonunion, and one with heterotopic ossification.

CONCLUSIONS

Starr frame-assisted and minimally invasive internal fixation could stabilize the anterior and posterior pelvic rings simultaneously, overcoming the difficulty of fracture reduction. This technique can help patients with early postoperative weight-bearing and improved functional outcomes, providing a novel modality for the minimally invasive treatment of pelvic ring injuries.

XR (Extended Reality: Virtual Reality, Augmented Reality, Mixed Reality) Technology in Spine Medicine: Status Quo and Quo Vadis

In recent years, with the rapid advancement and consumerization of virtual reality, augmented reality, mixed reality, and extended reality (XR) technology, the use of XR technology in spine medicine has also become increasingly popular. The rising use of XR technology in spine medicine has also been accelerated by the recent wave of digital transformation (i.e., case-specific three-dimensional medical images and holograms, wearable sensors, video cameras, fifth generation, artificial intelligence, and head-mounted displays), and further accelerated by the COVID-19 pandemic and the increase in minimally invasive spine surgery. The COVID-19 pandemic has a negative impact on society, but positive impacts can also be expected, including the continued spread and adoption of telemedicine services (i.e., tele-education, tele-surgery, tele-rehabilitation) that promote digital transformation. The purpose of this narrative review is to describe the accelerators of XR (VR, AR, MR) technology in spine medicine and then to provide a comprehensive review of the use of XR technology in spine medicine, including surgery, consultation, education, and rehabilitation, as well as to identify its limitations and future perspectives (status quo and quo vadis).

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.

Total elbow arthroplasty using an augmented reality-assisted surgical technique

BACKGROUND

Precision placement of implants in total elbow arthroplasty (TEA) using conventional surgical techniques can be difficult and riddled with errors. Modern technologies such as augmented reality (AR) and 3-dimensional (3D) printing have already found useful applications in many fields of medicine. We proposed a cutting-edge surgical technique, augmented reality total elbow arthroplasty (ARTEA), that uses AR and 3D printing to provide 3D information for intuitive preoperative planning. The purpose of this study was to evaluate the accuracy of humeral and ulnar component placement using ARTEA.

METHODS

Twelve upper extremities from human frozen cadavers were used for experiments performed in this study. We scanned the extremities via computed tomography prior to performing TEA to plan placement sites using computer simulations. The ARTEA technique was used to perform TEA surgery on 6 of the extremities, whereas conventional (non-ARTEA) techniques were used on the other 6 extremities. Computed tomography scanning was repeated after TEA completion, and the error between the planned and actual placements of humeral and ulnar components was calculated and compared.

RESULTS

For humeral component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 1.4° ± 0.6° vs. 4.4° ± 0.9° in total rotation (P = .002) and 1.5 ± 0.6 mm vs. 8.6 ± 1.3 mm in total translation (P = .002). For ulnar component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 5.5° ± 3.1° vs. 19.5° ± 9.8° in total rotation (P = .004) and 1.5 ± 0.4 mm vs. 6.9 ± 1.6 mm in total translation (P = .002). Both rotational accuracy and translational accuracy were greater for joint components replaced using the ARTEA technique compared with the non-ARTEA technique (P < .05).

CONCLUSION

Compared with conventional surgical techniques, ARTEA had greater accuracy in prosthetic implant placement when used to perform TEA.

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.

Open reduction and navigated Iliosacral screws for vertically unstable pelvic fractures

AIMS

To evaluate clinical and radiological results of vertically unstable pelvic fractures managed by open reduction and navigated iliosacral screws.

PATIENTS AND METHODS

The study included eleven patients with complex posterior ring fractures with vertical instability admitted to our hospital and managed with CT navigated iliosacral screws. There were 7 type C1, 2 C2 and 2 C3, according to Tile classification. Three patients presented a spino-pelvic dissociation and four a vertical sacral fracture affecting the foramina (Denis 2). Vertical displacement, pelvic deformity and asymmetry were measured. Tornetta and Matta criteria were used to assess the quality of pelvic reduction.

RESULTS

An excellent reduction was achieved in 9 fractures and a good reduction in two. Asymmetry index improved from 13.18 to 2.72. Deformity index improved from 0.049 to 0.010. Only two patients with a Denis 2 fracture showed secondary displacement during follow-up. Four patients presented neurological complications due to their initial injuries. Seven patients were able to resume their previous activities.

CONCLUSION

CT navigated IS screws provide enough stability after an anatomic reduction of the fracture. There was no complication related to screw insertion and adequate screw positioning was achieved in all the cases.

Clinical impact of intraoperative cone beam tomography and navigation for displaced acetabular fractures: a comparative study at medium-term follow-up

INTRODUCTION

The use of per-operative cone beam tomography imaging for displaced acetabular fractures yields increased post-operative articular reduction accuracy. This study evaluates the need for total hip replacement (THR) and hip-related functional outcomes in patients with displaced acetabular fractures treated with O-ARM guidance compared to those treated under C-ARM guidance.

MATERIALS AND METHODS

This is a prospective matched cohort study. Adult patients (35) with acetabular fractures operated under O-ARM guidance were included. These were matched (age, fracture type) to classically treated patients (35) from our data base. The primary outcome was the need for THR during three year follow-up period. Secondary outcomes were functional scores [Harris Hip score (HHS), Postel-Merle d'Aubigné (PMA)] and hip osteoarthritis grade at three year follow-up. Correlation between reduction gap and THR was evaluated.

RESULTS

At three years, five patients were lost to follow-up in O-ARM group and four in control group. Two patients (6.66%) in the O-ARM group needed THR compared to eight patients in controls (25.80%) (p = 0.046). Hip X-ray osteoarthritis grade averaged 0.00 in patients without THR in O-ARM group compared to 0.22 in patients without THR in controls (p = 0.008). HHS averaged 95.79 in patients without THR in O-ARM group, compared to 93.82 in patients without THR in the control group (p = 0.41%). PMA averaged 17.25 in patients without THR in the O-ARM group compared to 17.04 in patients without THR in group 2 (p = 0.37). Evaluation of correlation between reduction gap and THR rate yielded OR = 1.22 (1.06-1.45).

DISCUSSION

Increased accuracy in articular reduction, with per-operative three-dimensional control of impaction, in acetabular fractures led to significantly less need for THR in patients treated under O-ARM. Patients in both groups are comparable for functional outcomes because those with the lowest scores were offered THR. Per-operative cone beam guidance and navigation use are recommended in tertiary referral centres for acetabular trauma.

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.

Use of External Fixators as a 3-Dimensional Navigation Drill Guide for Arthroscopic Ankle Arthrodesis

In this article, we describe a novel technique using external fixators and cannulated screws to construct a 3-dimensional navigation drill guide to predict the screw trajectory before screw insertion that can prevent screw collision during arthroscopic ankle arthrodesis. Four orthopedic residents who had no prior experience of ankle arthrodesis were instructed on how to use the 3-dimensional navigation drill guide and where to insert the screws for ankle arthrodesis. Each resident inserted 6.5 cannulated screws on 8 sawbone ankle models using the device and the C-arm fluoroscopy. An experienced attending surgeon also inserted the same screws on 2 sawbone ankle models to find out if there is any difference between the experienced and inexperienced surgeons. All four residents and an attending surgeon did not experience any collision of screws for the three cannulated screws. Notably, one resident had collision of the 4th screw on his first sawbone model. On the second saw bone model, all surgeons could insert 5 screws without redrilling. A 3-dimensional navigation drill guide constructed with external fixators can assist surgeons in implementing percutaneous screws for arthroscopic ankle arthrodesis.

Computer navigation-assisted minimally invasive percutaneous screw placement for pelvic fractures

Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability. Traditional open surgery has a large amount of bleeding, which is not suitable for patients with acute pelvic fracture. Navigation-guided, percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages, which include less trauma, faster recovery times, and less bleeding. However, due to the complexity of pelvic anatomy, doctors often encounter some problems when using navigation to treat pelvic fractures. This article reviews the indications, contraindications, surgical procedures, and related complications of this procedure for the treatment of sacral fractures, sacroiliac joint injuries, pelvic ring injuries, and acetabular fractures. We also analyze the causes of inaccurate screw placement. Percutaneous screw placement under navigational guidance has the advantages of high accuracy, low incidence of complications and small soft-tissue damage, minimal blood loss, short hospital stays, and quick recovery. There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones. However, computer navigation technology requires extensive training, and attention should be given to avoid complications such as screw misplacement, intestinal injury, and serious blood vessel and nerve injuries caused by navigational drift.

Morphometric analysis of the anterior column of the acetabulum and safety of intramedullary screw fixation for its fractures in Indian population: a preliminary report

INTRODUCTION

Morphometric variations of the anterior column of the acetabulum have been described in the literature for its complex structure, which can influence the safe containment of intramedullary screw for fixation of its fractures. The purpose of this CT-based study is to present a preliminary report on the morphometric variations and safety of intramedullary screw fixation of the anterior column of the acetabulum in the Indian population.

METHODS

CT-based data from 102 uninjured pelves were retrospectively analyzed in iPlanⓇ BrainLab AG, Feldkirchen, Germany. Narrowest zones around acetabulum and superior pubic ramus were measured. We calculated the axis of the anterior column of the acetabulum by joining the centres of these narrowest zones. Standard screws trajectories were directed along this axis. Screw length up to the first cortical perforation, the distance of the exit point from the pubic symphysis, and the length of the anterior column up to the pubic tubercle were measured.

RESULTS

The osseous corridor of the anterior column of acetabulum had variable cross-section along its length with two constriction zones, first in the acetabular region and second in the superior pubic ramus. Only 54% of our cases allowed safe applicability of 6.5-mm-diameter screw trajectories with safety margin of 2 mm on either side of the screw. Significant morphometric and screw applicability-related differences were observed among male and female cases with males having a wider osseous corridor in general. Elimination of safety margin results in a significant increase in the screw applicability.

CONCLUSION

The osseous corridor of the anterior column varies in its dimensions from individual to individual. Standard screws of 6.5-mm and 7.3-mm diameters may not be safe for intramedullary screw fixation in every patient and carry a risk of cortical violation when a 2 mm of width around the screw is considered as a safety margin. However, with a precise screw placement within the extents of the cortices of the anterior column, 6.5-mm screws can be applied in most of the female cases and 7.3-mm screws can be applied in most of the male cases for anterior column fixation.

Image intensifier distortion influences a surgeon's ability to aim guidewires during orthopaedic procedures

OBJECTIVE

Accurate insertion of a guidewire under image intensifier guidance is a fundamental skill required by orthopaedic surgeons. This study investigated how image intensifier distortion, which is composed of pin-cushion and sigmoidal components, changed the apparent trajectory of a guidewire, and the resulting deviation between the intended and actual guidewire tip position.

MATERIALS AND METHODS

Intraoperative image intensifier images for 220 consecutive patients with hip fractures were retrospectively corrected for distortion using a global polynomial method. The deviation between the intended and actual guidewire tip positions was calculated. Additional distortion parameters were tested using an image intensifier produced by a different manufacturer, and a flat-panel c-arm.

RESULTS

Deviation was approximately 1 cm if the guidewire was aimed from the extremity of the image and almost 0 if the entry point was only 20% from the centre (p < 0.001). The direction of deviation was different for left and right hips, with average deviations measuring 3 mm proximal and 5 mm distal respectively (p < 0.001). The flat-panel c-arm almost completely eliminated distortion.

CONCLUSIONS

Image intensifier distortion significantly altered the intended trajectory of a guidewire, with guidewires aimed from the image periphery more affected than guidewires aimed from the centre. Furthermore, for right hips, guidewires should be aimed distal to their intended position, and for left hips they should be aimed proximal to achieve their desired position. The flat-panel c-arm eliminated the effect of distortion; hence, it may be preferable if precision in guidewire positioning is vital.

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.

Guidance for Treatment of Pelvic Acetabular Injuries with Precise Minimally Invasive Internal Fixation Based on the Orthopaedic Surgery Robot Positioning System

Pelvic acetabular fracture is a common kind of fracture, mostly caused by high energy injuries. It is associated with high mortality and disability rates. The aim of surgical treatment of pelvic acetabular fractures is to restore the symmetry and stability of the pelvic ring structure and the anatomical structure of acetabular. Open reduction internal fixation is often used for the treatment of such fractures, but open surgery is in cases of serious injury, more bleeding, and high risk of infection. With the development of minimally invasive technology and the concept of the bone channel structure, the percutaneous lag screw technique for the treatment of pelvic and acetabular fractures has been applied in clinical practice and has proven to be effective. However, the anatomical structure of the pelvis and acetabulum is complex, and there are many important nerves and vessels adjacent to it. Traditional fluoroscopy screw placement is prone to screw malposition, and even minor angle changes may lead to screw perforation and damage of nerve vessels. The problem of radiation exposure is also noteworthy. Robotic-assisted surgery can be used to carry out screw position planning through preoperative imaging, intraoperative real-time tracking, and mechanical arm assistance to ensure that the screw placement position is consistent with the planning. In this way, robotic-assisted surgery can be used to accurately insert lag screws, and can reduce surgical risk and radiation exposure. This guide uses the TiRobot system as an example to describe the application of robot surgery in detail, aiming at standardizing the application of robots in orthopaedic surgery.

[Effectiveness analysis of three-dimensional printing assisted surgery for unstable pelvic fracture]

OBJECTIVE

To evaluate the effectiveness of three-dimensional (3D) printing assisted internal fixation for unstable pelvic fractures.

METHODS

The clinical data of 28 patients with unstable pelvic fractures admitted between March 2015 and December 2017 were retrospectively analyzed. The patients were divided into two groups according to different surgical methods. Eighteen cases in the control group were treated with traditional anterior and posterior open reduction and internal fixation with plate; 10 cases in the observation group were treated with 3D printing technology to make pelvic models and assist in shaping the subcutaneous steel plates of the anterior ring. Sacroiliac screw navigation template was designed and printed to assist posterior ring sacroiliac screw fixation. There was no significant difference between the two groups in gender composition, age, cause of injury, fracture type, and time interval from injury to surgery ( P>0.05). The operation time, intraoperative blood loss, intraoperative fluoroscopy times, incision length, waiting time for weight-bearing exercise, and fracture healing time were recorded and compared between the two groups. Majeed score was used to evaluate the function at last follow-up. At immediate after operation, the reduction was evaluated according to Matta imaging scoring criteria, and the success of sacroiliac joint screw implantation in the observation group was evaluated. The deviation of screw entry point and direction between postoperative screws and preoperative simulated screws were compared in the observation group.

RESULTS

All the operation was successfully completed, and all patients were followed up 6-18 months (mean, 14.4 months). In the control group, 1 case had wound infection and 2 cases had deep vein thrombosis. No serious complication such as important blood vessels, and nerve injury and pulmonary embolism occurred in other patients in the two groups. No screw pulling out or steel plate breaking occurred. The operation time, intraoperative blood loss, fluoroscopy times, incision length, and waiting time for weight-bearing exercise of the control group were significantly more than those of the observation group ( P<0.05); there was no significant difference in fracture healing time between the two groups ( t=0.12, P=0.90). There was no significant difference in reduction quality between the two groups at immediate after operation ( Z=-1.05, P=0.30); Majeed score of the observation group was significantly better than that of the control group at last follow-up ( Z=-2.42, P=0.02). The success rate of sacroiliac joint screw implantation in the observation group reached category Ⅰ. In the observation group, the deviation angle of the direction of the screw path between the postoperative screw and the preoperative simulated screw implant was (0.09±0.22)°, and the deviation values of the entry points on the X, Y, and Z axes were (0.13±0.63), (0.14±0.58), (0.15±0.53) mm, respectively. There was no significant difference when compared with those before the operation (all values were 0) ( P>0.05).

CONCLUSION

Computer design combined with 3D printing technology to make personalized pelvic model and navigation template applied to unstable pelvic fractures, is helpful to accurately place sacroiliac screw, reduce the operation time, intraoperative blood loss, and the fluoroscopy times, has good waiting time for weight-bearing exercise and function, and it is an optional surgical treatment for unstable fractures.

Robot-assisted Minimally-invasive Internal Fixation of Pelvic Ring Injuries: A Single-center Experience

Objective

To investigate the indications, surgical strategy and techniques, safety, and efficacy of robot‐assisted minimally‐invasive internal fixation of pelvic ring injuries.

Methods

The clinical data of 86 patients with anterior and posterior pelvic ring injuries who underwent robot‐assisted minimally‐invasive internal fixation were retrospectively analyzed. The patients included 57 men and 29 women aged between 22 and 75 years, with an average age of (40.2 ± 13.6) years. According to the Tile classification, there were 5 (5.8%) type A2, 48 (55.8%) type B, and 33 (38.4%) type C fractures. The surgical plans were formulated based on the injury type of the pelvic ring, the effectiveness of the reduction, and the integrity of the osseous channel. Posterior pelvic ring injuries were treated with robot‐assisted percutaneous cannulated screw fixation of the sacroiliac joint. Anterior pelvic ring injuries were treated with robot‐assisted percutaneous cannulated screw fixation of the pubic ramus, INFIX fixation, or a “hybrid” fixation. The surgical complications and the efficacy of the surgical treatments were analyzed.

Results

A total of 274 screws were inserted with robotic assistance, of which 262 screws were successfully inserted to a satisfactory position on the first attempt. The number of screws placed per person was 3.2 on average, and the average operation time was 175 min (35–280 min). Fluoroscopies were performed an average of 29.1 times (range, 9–63 times), and it took 6.1 s to place each screw. There were 13 unsatisfactory guiding needle placements during the surgeries, among 7 of which cutting or penetration of the cortex was re‐planned until satisfactory insertions; 1 penetrated the pubic cortex, causing hemorrhage of the “crown of death,” and was changed to “hybrid surgery”. The robot‐assisted surgical wounds all healed by primary intention with satisfactory position and precision of screw insertions. All patients were followed up for 3–6 months, with an average of 4.2 months. There were two postoperative fixation failures, in which both patients had separated symphysis pubes after hybrid surgery. The average Majeed score at the last follow‐up was 92.4 points.

Conclusions

Robot‐assisted surgery is accurate and minimally invasive, with a high success rate for one‐time screw placement and satisfactory clinical results. The indications and surgical strategy should be rigorously selected, the level of surgical techniques mastered, and the operating procedures standardized, all of which may help to prevent surgical complications. Robot‐assisted surgery provides a novel modality for the minimally‐invasive treatment of pelvic ring injuries.

Intraoperative Cone Beam Tomography and Navigation for Displaced Acetabular Fractures: A Comparative Study

OBJECTIVES

To evaluate the accuracy of reduction of the acetabular articular surface using an intraoperative computed tomography scanner (O-Arm) and screw navigation compared with a classical open technique.

DESIGN

Prospective matched cohort study.

SETTING

Tertiary referral center.

PATIENTS/PARTICIPANTS

Adult patients with acute acetabular fractures were included in the study. All patients were treated by 2 senior surgeons using intraoperative imaging and screw navigation.

MAIN OUTCOME MEASUREMENTS

The primary outcome measure was articular reduction. Secondary outcomes were radiation dosage, operative variables [operative time, time for image acquisition, intraoperative bleeding (cell saver), number of surgical plates, and number of screws], and postoperative variables (first postoperative day pain on the visual analog scale, postoperative transfusion, and hemoglobin change). P < 0.05 was considered statistically significant.

RESULTS

Thirty-five patients were treated in the inclusion period (2016-2017) and were matched to 35 cases in our database (2013-2016). Mean age was 43 years, and the most common fracture type was a both-column fracture (OTA/AO type C). Postoperative image analysis showed that reduction was achieved in 87.1% of the cases in the O-Arm group versus 64.7% in the control group (P < 0.05). Mean gap of the articular fragments was 3.6 mm in the O-Arm group compared with 5.6 mm (P = 0.01) in the control group. There was no significant difference between the 2 groups in regards to all other studied variables except a decrease in intraoperative blood loss and transfusions and an increase in surgical time with the O-Arm group. Finally, the total radiation dose was decreased using the intraoperative O-Arm compared with a routine postoperative computed tomography scan (dose length product in O-Arm: 498 mGy.cm; dose length product in historical group: 715 mGy.cm).

CONCLUSIONS

Using intraoperative imaging and screw navigation for displaced acetabular fractures allow screw navigation with increasing articular surface reduction accuracy. Operative and anesthesia times were not increased, whereas radiation exposure to the patient was significantly decreased. We recommend the use of intraoperative imaging for the treatment of displaced acetabular fractures.

LEVEL OF EVIDENCE

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

Percutaneous Fixation by Internal Cemented Screw for the Treatment of Unstable Osseous Disease in Cancer Patients

Interventional radiology expertise in image guidance has expanded the treatment options for cancer patients with unstable osseous disease. Percutaneous fixation by internal cemented screw (FICS) describes the technique by which the interventional radiologist stabilizes a fracture or impending fracture with the percutaneous placement of a cannulated screw that is locked in position by polymethyl methacrylate cement. The durable metallic screws provide added resistance to torque and tension stresses that complement the axial compression resistance of cement. Compared with cementoplasty alone, the procedure has been advanced as a more durable and precise technique for stabilization of osseous disease for certain disease presentations in cancer patients. The application of advanced image guidance techniques improves upon existing percutaneous surgical techniques to facilitate approaches that would otherwise prove quite challenging, particularly with stabilization of the pelvic flat bones. This article examines the applications of percutaneous FICS procedures for the treatment of unstable osseous disease in cancer patients. Indications, techniques, and follow-up care are reviewed. Case examples in which FICS can be performed in unstable pathology are detailed.

Posterior pelvic ring fractures: Intraoperative 3D-CT guided navigation for accurate positioning of sacro-iliac screws

INTRODUCTION

Posterior pelvic ring fractures frequently pose a problem of stability with an elevated risk of complications. The traditional method of percutaneous sacroiliac (SI) stabilization with the use of fluoroscopic image amplifiers demands a high degree of experience and has an elevated risk of screws' malpositioning.

HYPOTHESIS

Intraoperative 3D-CT scan coupled with a navigation system (O-Arm^©) can allow screw fixation accuracy while limiting the risk of complications for the treatment of posterior pelvic ring fractures.

MATERIAL AND METHODS

Patients with posterior pelvic ring fractures stabilized with percutaneous SI screws through O-Arm^© navigation from August 2008 to December 2017 were analyzed. A modified Gras classification was used to determine screws' positioning under CT visualization, and intraoperative and early postoperative complications were documented.

RESULTS

Among the 21 patients evaluated, 14 men and 7 women with a mean age of 57.8 years (range 25-91), receiving 39 screws, the rate of misplacement was low: 82% grade I, 15.4% grade II, and only 2.6% grade III. Only one patient underwent revision surgery, not because of misplacement but rather for a secondary implant loosening. No complications occurred in this series.

DISCUSSION

This study documented a large series of patients treated for pelvic ring fractures using the intraoperative 3D-CT O-Arm^© guided navigation. This surgical approach provided a precise and safe SI screw positioning with no complications.

LEVEL OF EVIDENCE

IV, Retrospective study.

Robot-assisted percutaneous screw placement combined with pelvic internal fixator for minimally invasive treatment of unstable pelvic ring fractures

Purpose

The purpose of this study was to investigate the safety and efficacy of the combination of robot‐assisted percutaneous screw placement and pelvic internal fixator (INFIX) for minimally invasive treatment of unstable anterior and posterior pelvic ring injuries.

Methods

From September 2016 to June 2017, twenty‐four patients with unstable anterior and posterior pelvic ring injuries were treated with TiRobot‐assisted percutaneous sacroiliac cannulated screw fixation on the posterior pelvic ring combined with robot‐assisted pedicle screw placement in the anterior inferior iliac spine along with INFIX on the anterior pelvic ring. The results of the treatment, including surgery duration, fluoroscopy frequency, total drilling, amount of blood loss, fracture healing time, and postoperative functional outcomes were recorded and compared with another 21 similar patients who underwent conventional manual positioning surgery.

Results

The TiRobot group incurred significantly shorter duration of surgery; less fluoroscopy frequency, intraoperative bleeding, and total drilling than in the conventional group (P < 0.05). Postoperative radiological follow‐up showed that all screws were in the safe area and no screw penetrated the cortex. All wounds healed by primary intention and no iatrogenic damage to the blood vessels, nerves, and organs occurred. Patients showed good tolerance to INFIX and reported no discomfort. The mean follow‐up duration was 5.4 months; the fractures were all healed, no loss of reduction occurred, and the mean Majeed score at the last follow‐up did not show any difference.

Conclusion

TiRobot‐assisted percutaneous screw placement combined with INFIX for the anterior and posterior pelvic ring injuries is accurate, safe, less invasive, and shows satisfactory efficacy, suggesting it is a better method for minimally invasive treatment of unstable pelvic ring fractures.

Planning, guidance, and quality assurance of pelvic screw placement using deformable image registration

Percutaneous pelvic screw placement is challenging due to narrow bone corridors surrounded by vulnerable structures and difficult visual interpretation of complex anatomical shapes in 2D x-ray projection images. To address these challenges, a system for planning, guidance, and quality assurance (QA) is presented, providing functionality analogous to surgical navigation, but based on robust 3D-2D image registration techniques using fluoroscopy images already acquired in routine workflow. Two novel aspects of the system are investigated: automatic planning of pelvic screw trajectories and the ability to account for deformation of surgical devices (K-wire deflection). Atlas-based registration is used to calculate a patient-specific plan of screw trajectories in preoperative CT. 3D-2D registration aligns the patient to CT within the projective geometry of intraoperative fluoroscopy. Deformable known-component registration (dKC-Reg) localizes the surgical device, and the combination of plan and device location is used to provide guidance and QA. A leave-one-out analysis evaluated the accuracy of automatic planning, and a cadaver experiment compared the accuracy of dKC-Reg to rigid approaches (e.g. optical tracking). Surgical plans conformed within the bone cortex by 3-4 mm for the narrowest corridor (superior pubic ramus) and  >5 mm for the widest corridor (tear drop). The dKC-Reg algorithm localized the K-wire tip within 1.1 mm and 1.4° and was consistently more accurate than rigid-body tracking (errors up to 9 mm). The system was shown to automatically compute reliable screw trajectories and accurately localize deformed surgical devices (K-wires). Such capability could improve guidance and QA in orthopaedic surgery, where workflow is impeded by manual planning, conventional tool trackers add complexity and cost, rigid tool assumptions are often inaccurate, and qualitative interpretation of complex anatomy from 2D projections is prone to trial-and-error with extended fluoroscopy time.

Study of the X-Ray Diagnosis of Unstable Pelvic Fracture Displacements in Three-Dimensional Space and its Application in Closed Reduction

ABSTRACTS Objective: To study the method of X-ray diagnosis of unstable pelvic fractures displaced in three-dimensional (3D) space and its clinical application in closed reduction.

METHODS

Five models of hemipelvic displacement were made in an adult pelvic specimen. Anteroposterior radiographs of the pelvis were analyzed in PACS. The method of X-ray diagnosis was applied in closed reductions. From February 2012 to June 2016, 23 patients (15 men, 8 women; mean age, 43.4 years) with unstable pelvic fractures were included. All patients were treated by closed reduction and percutaneous cannulate screw fixation of the pelvic ring. According to Tile's classification, the patients were classified into type B1 in 7 cases, B2 in 3, B3 in 3, C1 in 5, C2 in 3, and C3 in 2. The operation time and intraoperative blood loss were recorded. Postoperative images were evaluated by Matta radiographic standards.

RESULTS

Five models of displacement were made successfully. The X-ray features of the models were analyzed. For clinical patients, the average operation time was 44.8 min (range, 20-90 min) and the average intraoperative blood loss was 35.7 (range, 20-100) mL. According to the Matta standards, 7 cases were excellent, 12 cases were good, and 4 were fair.

CONCLUSIONS

The displacements in 3D space of unstable pelvic fractures can be diagnosed rapidly by X-ray analysis to guide closed reduction, with a satisfactory clinical outcome.

Contemporary acetabular fracture surgery

In the time since Letournel popularised the surgical treatment of acetabular fractures, more than 25 years ago, there have been many changes within the field, related to patients, surgical technique, implants and post-operative care. However, the long-term outcomes appear largely unchanged. Does this represent stasis or have the advances been mitigated by other negative factors? In this article we have attempted to document the recent changes within the surgery of patients with a fracture involving the acetabulum, outline contemporary management, and identify the major problem areas where further research is most needed.

Cite this article: Bone Joint J 2017;99-B:1125–31

[Percutaneous internal fixation of pelvic fractures. German version]

BACKGROUND

Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported.

OBJECTIVES

The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods.

METHODS

A review of the literature is provided and the techniques for anterior and posterior pelvic stabilization are discussed.

RESULTS

High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilizing the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be a devastating complication. The retrograde anterior column screw (RACS) is a technique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilization and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation.

CONCLUSION

Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

The added value of intraoperative CT scanner and screw navigation in displaced posterior wall acetabular fracture with articular impaction

Posterior wall with transverse acetabular fractures represents the most common type of acetabular fractures and is generally associated with poorer outcomes. This is caused by improper visualization of the fragments leading to imperfect reductions. Navigation in pelvic and acetabular trauma is reserved nowadays to non-displaced or mildly displaced fractures. To add to that, perioperative control of reduction is difficult using the conventional X-ray. The described 3D imaging method allowed proper reduction control. On the other hand, screw navigation of acetabular screws enabled better control of screw position as well as screw placement in otherwise inaccessible zones. In conclusion, peroperative 3D imaging and screw navigation optimize fracture reduction promoting better radiological and functional results.

Is cannulated-screw fixation an alternative to plate osteosynthesis in open book fractures? A biomechanical analysis

OBJECTIVES

The current biomechanical work compares the symphyseal and sacroiliac stability obtained with two systems of bone osteosynthesis. The two methods of fixation compared were the 6-hole suprapubic non-locked plate and pubic fixation with two cannulated screws, a novel technique that can be applied percutaneously in the clinical practice. The aim of this study was to examine the validity of the use of two-cannulated-screws osteosynthesis in order to minimize the secondary effects of open fixation, especially in patients in whom an open reduction is contraindicated.

MATERIALS AND METHODS

A biomechanical study was designed in 9 fresh, human pelvis specimens, simulating an AO B1.1 type injury, using both fixation systems sequentially in each specimen. In both parts of the test, the specimens were subjected to an axial load of 300N. Displacements and rotations between the different pelvic elements were studied by means of a discrete set of points. The absence of differences between the two systems has been set as the null hypothesis.

RESULTS

There were significant differences in favor of the cross-cannulated screws in most of the displacements measured at the pubic symphysis and sacroiliac joint.

CONCLUSIONS

Fixation of the AO B1.1 type fractures with cross cannulated screws restores the biomechanical behavior of the pubic symphysis, obtaining better stability than fixation with the 6-hole non-locked plate. To date, no comparative, biomechanical studies have been conducted with these two systems of osteosynthesis. This study demonstrates that cross-cannulated screws fixation of the pubic symphysis in AO B1.1 pelvic fractures should be considered as an alternative to the conventional plating system.

Precision insertion of percutaneous sacroiliac screws using a novel augmented reality-based navigation system: a pilot study

PURPOSE

Augmented reality (AR) enables superimposition of virtual images onto the real world. The aim of this study is to present a novel AR-based navigation system for sacroiliac screw insertion and to evaluate its feasibility and accuracy in cadaveric experiments.

METHODS

Six cadavers with intact pelvises were employed in our study. They were CT scanned and the pelvis and vessels were segmented into 3D models. The ideal trajectory of the sacroiliac screw was planned and represented visually as a cylinder. For the intervention, the head mounted display created a real-time AR environment by superimposing the virtual 3D models onto the surgeon's field of view. The screws were drilled into the pelvis as guided by the trajectory represented by the cylinder. Following the intervention, a repeat CT scan was performed to evaluate the accuracy of the system, by assessing the screw positions and the deviations between the planned trajectories and inserted screws.

RESULTS

Post-operative CT images showed that all 12 screws were correctly placed with no perforation. The mean deviation between the planned trajectories and the inserted screws was 2.7 ± 1.2 mm at the bony entry point, 3.7 ± 1.1 mm at the screw tip, and the mean angular deviation between the two trajectories was 2.9° ± 1.1°. The mean deviation at the nerve root tunnels region on the sagittal plane was 3.6 ± 1.0 mm.

CONCLUSIONS

This study suggests an intuitive approach for guiding screw placement by way of AR-based navigation. This approach was feasible and accurate. It may serve as a valuable tool for assisting percutaneous sacroiliac screw insertion in live surgery.

Rationale for more consistent choice of surgical approaches for acetabular fractures

OBJECTIVES

All acetabular fractures are difficult to treat surgically, but there are four types involving two columns that are particularly challenging. The choice of surgical approach is crucial. The purpose of the study was to determine and evaluate the factors influencing the choice of surgical approach for two-column acetabular fractures. We hypothesised that more accurate preoperative planning, sophisticated technical capabilities, and evolution of surgeon experience will result in more consistent use of non-extensile single surgical approaches. We also evaluated the outcomes of surgical treatment and the correlation with the surgical approach used.

DESIGN

Retrospective cohort study.

PATIENTS AND METHODS

A total of 156 patients with 157 acetabular fractures involving two columns (Letournel T-types and both-column) treated surgically in a 25-year period (1988-2013) were included in the study. The acetabular fractures in this study were divided into two groups according to the date of surgery: 81 in Group 1 (1998-2002) and 76 in Group 2 (2003-2013). All fractures were classified preoperatively according to the Judet and Letournel classification system and Matta's categorisation of surgical approach. Four surgical approaches were used: single Kocher-Langenbeck (KL), single ilioinguinal (II), combined Kocher-Langenbeck and ilioinguinal (KL+II), and extended iliofemoral (EIF). The efficacy of the surgical approach utilised was assessed using three parameters: anatomical reduction, surgical time and intraoperative complications.

RESULTS

There was no statistical difference between Group 1 and Group 2 in the distribution of T-type (p=0.424) and both-column (p=0.425) fractures. In Group 2 more acetabular fractures were treated through single non-extensile approaches compared with Group 1 (90.8% vs. 54.3%, p<0.001). Increase in single approach surgery resulted in shorter mean surgical time (p<0.001) and significant increase in anatomical reduction (p=0.039). The frequency of intraoperative complications was not statistically different (p=0.07) between the two groups, but there was a trend to fewer complications in Group 2.

CONCLUSIONS

The surgical approaches chosen for acetabular fractures that involve two columns (Letournel T-types and both-column) should become more consistent. The results of this study indicate that the majority of such acetabular fractures can be treated successfully through single surgical approaches.

A novel electromagnetic navigation tool for acetabular surgery

BACKGROUND

Acetabular fracture surgery is demanding and screw placement along narrow bony corridors remains challenging. It necessitates x-ray radiation for fluoroscopically assisted screw insertion. The purpose of this cadaver study was to evaluate the feasibility, accuracy and operation time of a novel electromagnetic navigation system for screw insertion along predefined acetabular corridors.

METHODS

A controlled laboratory study with a total of 24 electromagnetically navigated screw insertions was performed on 8 cadaveric acetabula. 3 peri-acetabular bony corridors (QSS, Quadrilateral Surface Screw; IAS, Infra-Acetabular Screw; PCS, Posterior Column Screw) were defined and screws were placed in a defined order without fluoroscopy. Operation time was documented. Postoperative CT scans were performed to analyse accuracy of screw placement.

RESULTS

Mean cadaver age was 70.4 ± 11.7. Successful screw placement was accomplished in 22 out of 24 (91.7%) cases. The overall mean time for all 3 acetabular screws was 576.6 ± 75.9s. All 3 complications occurred during the placement of the IAS due to an impassable narrow bony corridor. QSS mean length was 50 ± 5mm, IAS mean length was 85 ± 10mm and PCS mean length was 120 ± 5mm.

CONCLUSION

In this cadaver study the novel electromagnetic navigation system was feasible to allow accurate screw placement without fluoroscopy in defined narrow peri-acetabular bony corridors.

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.

PMMA-augmented SI screw: a biomechanical analysis of stiffness and pull-out force in a matched paired human cadaveric model

INTRODUCTION

Current literature data and clinical experience show that the number of pelvic fractures continuously rises due to the increasing elderly population. In the elderly with suspected osteoporosis additional implant augmentation with bone cement seems to be an option to avoid secondary displacement. There are no reported biomechanical data in the literature comparing the fixation strength (and anchorage) of standard and augmented SI screws so far. The purpose of this study was to assess the biomechanical performance of cement-augmented versus non-augmented SI screws in a human cadaveric pelvis model.

MATERIAL AND METHODS

Six human cadaveric pelvises preserved with the method of Thiel were used in this study. Each pelvis was split to a pair of 2 hemi-pelvises, assigned to 2 different groups for instrumentation with one non-augmented or one contralateral cement-augmented SI screw, placed in the body of S1 in a randomized fashion. The osteosynthesis followed a standard procedure with 3D controlled percutaneous iliosacral screw positioning. A biomechanical setup for a quasistatic pullout test of each SI screw was used. Construct stiffness and maximum pullout force were calculated from the load-displacement curve of the machine data. Statistical evaluation was performed at a level of significance p = .05 for all statistical tests.

RESULTS

Stiffness and pullout force in the augmented group (501.6 N/mm ± 123.7, 1336.8 N ± 221.1) were significantly higher than in the non-augmented one (289.7 N/mm ± 97.1, 597.7 N ± 115.5), p = .04 and p = .014, respectively. BMD influenced significantly the pullout force in all study groups.

CONCLUSION

Cement augmentation significantly increased the fixation strength in iliosacral screw osteosynthesis of the sacrum in a biomechanical human cadaveric model.

The cement-augmented transiliacal internal fixator (caTIFI): an innovative surgical technique for stabilization of fragility fractures of the pelvis

INTRODUCTION

Analyzing the different age groups in a population who suffered a pelvic ring fracture it becomes obvious that there are important differences between the pelvic ring lesions of an elderly patient compared to a young adult concerning trauma mechanism, fracture pattern and therapeutic options. In the elderly patient it is very important to achieve maximum of stability if surgery is necessary in order to avoid early failure of the ostheosynthesis under mobilization with full weight bearing.

PATIENTS AND METHODS

15 patients (14 female) with fragility fractures of the pelvis that required surgical stabilization were eligible to participate in this study from December 2012 to December 2014. Such details were documented and analysed as patient demographics, mechanism of injury, fracture classification, operative treatment and postoperative radiological parameters of achieved bone-implant interface.

RESULTS

The average age of the patients was 79.9 years (SD 9.0 years). According to Rommens five patients had a fragility fracture of the pelvis Type II-c, one a Type III-c, six a Type IV-b and three a Type IV-c. Four patients were treated by a cement augmented transiliac internal fixation (caTIFI). Seven patients received a cement augmented iliolumbar fixation. In all these patients the Schanz screws applied to the ilium were placed in an oblique dorsoventral direction into the supraacetabular bone canal (mean length of screws 100 ± 20mm, max. 135 mm, min. 70 mm). Even though in four patients the iliosacral joint was hit tangential and one cortex perforation without any cement leakage appeared no revision surgery was necessary. Overall the clinical findings including mobilisation with full weight bearing showed a sufficient mechanically stability in all patients.

CONCLUSION

The focus of this study was to describe the modified surgical technique of the caTIFI with placing the Schanz screws from the posterior superior iliac spine to the anterior inferior iliac spine into the supraacetabular bone canal. Usage of cannulated and perforated Schanz screws gives the opportunity to control the correct position of the screws before implanting them. Another advantage is that additional stability can be obtained by cement augmentation. We believe that the new technique of the caTIFI provides a greater intraoperative versatility and a greater mechanical stability for fragility fractures of the pelvis.