The successful surgical management of pelvic ring disruptions and acetabular fractures relies on many important factors. These include patient resuscitation, a detailed diagnosis of the injury pattern, choosing and executing the proper open or percutaneous exposure(s), accurately reducing the injury sites, and providing safe and stable fixation without complications.1,2 Surgeons routinely use preoperative pelvic plain radiographs and computed tomography (CT) scans to understand the injury sites and their displacements so that the optimal treatment can be planned.
In certain patients, the intraoperative fluoroscopic findings are different than what had been noted on the preoperative imaging studies. For example, the initial pelvic imaging may have been obtained in a circumferential pelvic wrap such that the pelvic ring injuries and deformities are held reduced, and therefore cannot be identified.3 Subsequently, these unstable injury sites are discovered in the operating room after the circumferential wrap has been removed and intraoperative fluoroscopy performed (Figs. 1A–F). For some patients with acetabular fractures and fracture dislocations, the opposite occurs. For example, certain patients with unstable acetabular fracture dislocations will have the entirety of their initial imaging performed before a successful closed reduction. When the closed reduction is accomplished after the initial imaging or at the time of general anesthesia in the operating room, then the surgeon is faced with either halting the planned operation for repeat imaging or proceeding with a quickly, and perhaps poorly, revised operative plan based on the surprising intraoperative fluoroscopic findings.
Until now, the intraoperative assessment of the reduction accuracy and implant location, including screws inserted near the acetabular articular surface, has relied on the direct visualization and/or palpation of the cortical fracture lines through surgical wound intervals and multiplanar fluoroscopy.4,5 Along with intraoperative fluoroscopy, other more recent CT-based imaging technologies have been used in attempts to both assess the fracture reduction quality and implant safety.5–7 Due to a variety of factors, routine fluoroscopic imaging can be insufficient to assure the surgeon that the reduction is precise or that the inserted screw or applied plate has been properly located, especially for pelvic ring and acetabular fracture fixation.
Ziehm Imaging (Nuremburg, Germany) recently introduced advanced intraoperative fluoroscopic technology that provides rapidly acquired high-quality axial, sagittal, and coronal reconstructed images intraoperatively (Figs. 1E, F and 2). This allows the surgeon to identify any changes that occurred after the preoperative imaging was obtained and assess the fracture reduction quality and implant locations. This imaging is accomplished either before or after wound closure, but while the patient is still under anesthesia in the operating room. In this way, any necessary corrections can be performed before the patient leaves the operating room, thereby avoiding subsequent revision corrective surgery.
The Ziehm RFD 3D C-arm device is the same size as any standard fluoroscopy unit and requires no additional personnel to operate other than the radiology technician usually needed for intraoperative fluoroscopy. This mobile C-arm unit uses a 30 × 30-cm flat-panel technology and has a 165-degree routine arc of movement, thereby allowing extended fluoroscopic imaging. Using a combination of linear and rotating movements, that C-arm completes a 180-degree acquisition arc in less than 45 seconds. Patented “SmartScan” technology uses a variable isocenter that allows the device to generate a complete 3D cubical dataset with 19.8 cm edge length. The device reconstructs the acquired 400 pulsed fluoroscopic images into a high-resolution 3D data set, and the “CT scan quality” images are then reconstructed in the axial, sagittal, and coronal planes. The dataset can also be easily manipulated by the surgeon or technician on the display screen for real-time variable plane orientations, rotations, brightness, and contrast enhancements. Clinical evaluations of radiation exposure to the patient during pelvic and acetabular surgeries are ongoing; however, the Ziehm RFD 3D was found in cochlear surgeries to have 20% less radiation exposure as compared with routine CT scanning (Diana Arweiler-Harbeck, MD, unpublished data, 2017).
We have used the Ziehm RFD 3D C-arm unit for over 3 years to evaluate all our adult patients with traumatic pelvic ring disruptions and displaced acetabular fractures requiring operative repair. Each patient is anesthetized and placed on a radiolucent operating table (Mizuho OSI, Union City, CA) in either the supine or the prone position. The Ziehm RFD 3D C-arm unit is placed on the side opposite to the injury to be treated and the field of view targeted over the injured area. Once positioned and before the skin preparation and draping, standard fluoroscopic images are obtained in anteroposterior (AP), oblique, inlet, outlet, and lateral sacral views. In addition, fluoroscopic imaging using any other hip or pelvic view is obtained as determined by the surgeon to be necessary to fully assess the particular injury for the planned operation. The displacement patterns and deformities are identified and the osseous fixation pathways are verified.7
Next, the Ziehm RFD 3D technology is used. For the majority of our patients, the initial intraoperative routine pelvic fluoroscopic images reveal no new fracture positional changes, and the operation proceeds as planned. At the conclusion of the operation, the Ziehm “spin” procedure is performed to acquire the images needed to generate the intraoperative reconstruction imaging. This is accomplished after the closed or open reduction and internal fixation was completed, before wound closure and awakening the patient from anesthesia. Regardless if the procedure has been an open exposure or a percutaneous one, hemostasis is achieved before the rotational “spin” imaging process. The entire surgical field is then covered completely using 2 long sterile sheets clamped together in the midline (Fig. 3). This shrouding technique allows the rotational scan to be performed and the sheets to be removed without contaminating the surgical field. The beam is targeted by the radiology technician, and verified by the surgeon, in such a way that the fracture sites and implants to be assessed are within the field of view. Next, a preliminary check is performed with the C-arm being maneuvered through its planned complete arc of rotation. This step assures that the C-arm does not collide with the table, the patient, the arm boards, or other devices within the pelvic area, such as urinary catheter tubing, sequential compression device hoses, or other monitors. As the C-arm rotates, it is halted temporarily in its lateral position to assure that the selected field of view is within the plane of view needed to establish a rotational isocenter. If not, the anesthesia personnel assist in adjusting the operating table height accordingly. The collision check continues as the C-arm rotates into its oblique starting position.
After the centering of the AP and lateral planes is accomplished and the collision check is completed, the imaging commences and the C-arm rotates for 45 seconds through a 180-degree arc acquiring 400 pulsed images. The dataset is then processed within 30 seconds and the reconstructed images can be viewed and manipulated immediately by the surgeon on the display screen. The axial, coronal, and sagittal images obtained from the “spin” technique supplement routine fluoroscopic imaging, especially demonstrating reduction accuracy, marginal impaction elevation, loose body removal, and precise plate and screw locations. For these patients, the reconstructed imaging intraoperatively confirms the reduction accuracy and implant locations (Figs. 4A–H; see Figure, Supplemental Digital Content 1, http://links.lww.com/JOT/A600 for another case example; see Video, Supplemental Digital Content 2, http://links.lww.com/JOT/A601 showing the initial intraoperative, presurgery Ziehm C-arm spin to assess the closed reduction; see Video, Supplemental Digital Content 3 and 4, http://links.lww.com/JOT/A602 and http://links.lww.com/JOT/A603 for the initial intraoperative, presurgery coronal and axial scans produced by the Ziehm C-arm spin; see Figure, Supplemental Digital Content 5, http://links.lww.com/JOT/A604 for the subsequent intraoperative images and preparation for the postsurgery, intraoperative repeat spin; see Video, Supplemental Digital Content 6, http://links.lww.com/JOT/A605 showing the Ziehm RFD 3D C-arm unit spinning to create the intraoperative, postfixation scan; see Video, Supplemental Digital Content 7, http://links.lww.com/JOT/A606 showing the intraoperative, postfixation imaging produced; see Figures, Supplemental Digital Content 8, http://links.lww.com/JOT/A607 for examples of axial sections produced by the intraoperative Ziehm RFD 3D C-arm scan, as compared with the standard postoperative CT scan axial sections). Any implant-related artifacts can be mitigated by proper positioning of the C-arm unit. For example, in the initial patients who had trans-sacral iliosacral screws inserted, we noted that implant visualization was obliterated when the C-arm was in parallel with the screw. This problem was solved by positioning the C-arm with obliquity relative to the screw so that the acquisition arc was not parallel to the implant.
In our experience, a less common way that the rotational imaging is used occurs when the findings on the initial intraoperative fluoroscopic screening images do not match the preoperative imaging studies that were obtained at the time of the patient's hospital admission. As an example of this situation, substantial differences can be noted in those patients with unstable pelvic ring disruptions in whom a circumferential pelvic compressive binder or sheet is applied before the preoperative, initial injury imaging is performed. This is most commonly seen in patients with volume expanding “open book”8 pelvic ring injuries. The circumferential pelvic wrap reduces the injury sites and deformities causing the surgeon to both miss and underestimate injury sites. When the patients are under general anesthesia and properly positioned with the circumferential pelvic wrap removed, the Ziehm RFD 3D unit reconstructed images obtained to evaluate previously occult injury sites and assess the current status of known injury sites can cause the preoperative plan to be changed from percutaneous to an open procedure (Figs. 1A–E). Conversely in some patients with unstable lateral compression injuries, the deformities are accentuated by the circumferential pelvic wrapping such that open procedures are planned. However, once the binder is removed, the intraoperative imaging may show that the closed reduction is best for a percutaneous procedure.
From August 2015 to 2018, we used the Ziehm RFD 3D intraoperatively in over 600 patients with traumatic pelvic and acetabular injuries requiring surgical repair. For the majority of our patients, the entire reconstruction imaging process including wound preparation and surgical field isolation, draping, positioning the C-arm unit, performing the collision check and imaging acquisition, and the evaluation of the information on the display screen was less than 8 additional minutes of operating room time. In this IRB exempt study, review of our last 50 cases showed that the routine imaging for reduction and fixation had fluoroscopy time that averaged 3:48 minutes (range, 0:41–9:04 minutes), the shortest being for simple acetabular fractures and the longest for complex percutaneous pelvic ring reduction and fixation, which required many images for frame application, fracture reduction, and screw fixation. Ziehm RFD 3D spin times averaged 0:54 minutes (range, 0:30–1:36 minutes), the longer times being in those patients requiring more than one imaging spin. Radiation exposure to the patient averaged 88.3 mGys (range: 22.7–268.2 mGys), the lowest, again, being for simple acetabular fractures and the highest for complex percutaneous pelvic ring cases and those requiring more than one imaging spin.
In several patients with acetabular fractures, we identified retained loose bodies within the acetabular fossa that were previously thought to be have been removed but were still noted on the reconstructed images. These loose bodies were then removed during the same operative setting. In 2 patients, articular dome comminuted fragments were not properly reduced and required revision of the reductions. These poor reductions were not identifiable on routine pelvic images but were easily seen on the reconstructed images. Another patient had open reduction and internal fixation of an associated both column acetabular fracture, and the reconstructed axial images showed that the 2 lag screws had completely missed their intended posterior fracture fragment (Figs. 5A–C). The fracture was re-clamped, and the misdirected screws were exchanged for properly located screws (Figs. 5D–F). We have also used this technique in patients with complex and unusual fractures to assess the fracture sites after they have been reduced and clamped, but before fixation.
Patients with acetabular fracture dislocations had clinical pathology similar to the situation we experienced for lateral compression pelvic ring injuries noted above: specifically, reductions of what were thought to be unstable or obstructed fracture dislocations before the patient being anesthetized and positioned. Due to these changes identified on the routine intraoperative screening images, the Ziehm RFD 3D was used to obtain reconstructed axial, sagittal, and coronal images before the incision to assess the changes and assure that the operative plan was sufficient or needed to be changed. This occurred in several patients with unstable and displaced transverse acetabular fracture dislocations planned for open reductions; however, the intraoperative fluoroscopy and reconstructed imaging caused the plans to be changed to closed reduction and percutaneous fixation.
The Ziehm RFD 3D unit technology was particularly helpful in morbidly obese patients and acetabular fracture patients having associated pelvic ring injuries. The technique was also useful in those patients with posterior wall acetabular fracture and an associated seemingly irreducible femoral head dislocation. When the closed reduction is accomplished using general anesthesia, the Ziehm reconstruction imaging is then performed intraoperatively to assess the femoral head and posterior wall fracture reductions, and for any intra-articular debris that could have resulted from the reduction maneuver. In this way, an up-to-date and much more accurate treatment plan can be made. Using this new technology, we were able to avoid performing unnecessary operations in several patients based on the intraoperative reconstruction imaging findings after their closed reductions.
The successful surgical management of pelvic ring disruptions and acetabular fractures relies on many important factors. Surgeons routinely use preoperative pelvic plain radiographs and CT scans to understand the injury sites and their displacements so that the optimal treatment can be planned. Unfortunately, often these standard imaging studies provide information that is insufficient for successful intraoperative decision-making. Therefore, it is no surprise that advanced intraoperative pelvic imaging is not a new concept.
Intraoperative CT scanning was used by Kiel et al9 to assess acetabular reduction quality; however, they noted limitations in their assessments due to artifacts caused by the surgical implants. They recommended postoperative CT scans for such patients. In our patients, implant-related artifacts were not similarly problematic, likely due to our ability to manipulate the image contrast and brightness on the display screen. As noted previously, we also avoided implant-related artifacts by proper positioning of the C-arm unit. Nelson et al reported on the radiation risk to the patient and OR staff for plain x-ray, fluoroscopy, and portable cone-beam CT scanning in spinal surgery.10 As previously noted, the Ziehm RFD 3D was found in cochlear surgeries to have 20% less radiation exposure when compared with routine CT scanning (Diana Arweiler-Harbeck, MD, unpublished data, 2017), and clinical evaluations of radiation exposure during pelvic and acetabular surgeries are incomplete and ongoing. However, there is no doubt that the intraoperative use of the Ziehm RFD 3D spin fluoroscopy is additive to the patient radiation exposure due to routine intraoperative fluoroscopy, the standard CT preoperative scan, and any postoperative CT scans (see Figure and Video, Supplemental Digital Content 1–5, http://links.lww.com/JOT/A600, http://links.lww.com/JOT/A601, http://links.lww.com/JOT/A602, http://links.lww.com/JOT/A603, http://links.lww.com/JOT/A604 for a case example).
In our experience, the Ziehm RFD 3D technology has proven to be a great advance in intraoperative imaging for pelvic and acetabular injury care. The device functions as a routine C-arm fluoroscopy unit with the added advantage of reconstruction imaging. The intraoperative reconstruction imaging has allowed us to critically evaluate our reduction quality and implant locations during hundreds of operations. Any necessary reduction changes or implant adjustments can be made before awakening the patient from anesthesia. Using this new technology, poor quality reductions, misplaced implants, and secondary revision operations have been avoided. However, a variety of factors related to this new technology, such as operating room time, infection risk and especially, and radiation risk, warrant further investigation.
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