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Musculoskeletal Imaging |
1 Department of Surgery, Trauma Unit, Kantonsspital Basel, University Hospital,
University of Basel, Spitalstrasse 21, Basel 4031, Switzerland.
2 University Institute of Radiology, University Hospital Basel,
Switzerland.
3 Division of Trauma Surgery, University Hospital, Zürich,
Switzerland.
Received October 9, 2003;
accepted after revision December 7, 2003.
Address correspondence to T. Gross.
Introduction
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For the risks of an open approach to be reduced, minimally invasive percutaneous procedures were developed. Gay et al. [3] found that closed reduction and percutaneous fixation can be used successfully in selected articular acetabular fractures using a posterior approach that is dorsolateral to the greater sciatic notch. Also an anterior approach via the anterior inferior iliac spine was proposed [4]. In both instances, the approach was exclusively percutaneous.
We report a case of a mildly displaced oblique acetabular fracture for which a purely percutaneous path that was both safe and perpendicular to the fracture line did not exist. This fracture was successfully treated by an anteromedial approach with the femoral neurovascular bundle pushed laterally through a short ilioinguinal incision. This case shows that successful closed reduction and percutaneous fixation of an oblique acetabular fracture is feasible in selected cases without endangering the sciatic and femoral nerves.
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The tectal part of the oblique acetabular fracture line had a left anterolateral to posteromedial orientation (Fig. 1A, 1B, 1C, 1D, 1E). A surgical procedure was chosen to allow early mobilization after the accident.
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For a screw to be placed perpendicular to the fracture line, two principal approaches were possible: the posterior approach, which endangered the sciatic nerve, and the anterior approach, which put the femoral vessels and nerve at risk. We therefore concluded that a purely percutaneous approach was not feasible.
In an interdisciplinary meeting of trauma surgeons and interventional radiologists, it was decided that the femoral neurovascular bundle could be safeguarded by a small ilioinguinal incision; therefore, a hybrid openclosed anterior approach was chosen. A second screw was inserted percutaneously from the anterior inferior iliac spine to the sciatic notch.
The intervention was performed in a multifunctional imaging-guided therapy suite in which different radiologic and surgical techniques and equipmentCT, sonography, fluoroscopy, digital subtraction angiography, a new operating room table, and technique-based navigation system [5]are integrated into a sterile environment [6]. Surgery was performed with the patient under general anesthesia and with antibiotic prophylaxis. The patient was positioned in a right lateral decubitus position and was immobilized with a vacuum mattress.
Intraoperative planning was done using a helical CT scanner (HiSpeed Advantage, GE Healthcare). The imaging parameters were 140 kV, 380 mA, slice thickness of 5 mm, pitch of 1.5, and slice increment of 2.5 mm. To place the guide pins, we used a CT navigation system that we developed; it has a 3D optical digitizer to depict directly the spatial position of the surgical drill overlaid onto previously obtained CT images, is functional immediately after imaging, and allows seamless integration of additional intraoperative images [5].
After a short ilioinguinal incision was made, the femoral neurovascular bundle was identified and pushed slightly laterally to allow a safe placement of the medially inserted screw. For placement of the craniolateral screw, a short incision was made after defining the skin entry point by obtaining a CT scan for planning. After this procedure under CT navigation, two 2.8-mm Kirschner wires were placed (Figs. 1B and 1C). The position of the guide pin was then controlled with intraoperative CT, and its direction was extrapolated to the target position with the standard measuring functions of the CT console. The definitive total screw length according to the final position of the guide pin was calculated as the distance from the near to far cortex minus the width of the fracture gap plus 5 mm for the screw head and washer. Two 7.3-mm cannulated cancellous self-drilling, self-cutting lag screws with a threaded length of 32 mm and washers were chosen to prevent secondary rotation and guarantee good fracture compression.
The final CT control study that was performed with dose reduction (25 mA) revealed a correct position of the implants (Figs. 1B, 1C, 1D, 1E). A reduced dose is applied for intermediate and final control studies to minimize the patient's radiation exposure and if neither 3D reconstructions nor soft-tissue details are needed. Metal artifacts are a minor issue for this procedure even with low-dose CT because Kirschner wires and the cannulated titanium screws can easily be located in the surrounding bone.
During clinical follow-up, the patient did well: he was mobilized with partial weight-bearing the day after surgery and was almost pain-free. The patient was dismissed from the hospital 14 days after surgery. Two months after the intervention, he started full weight-bearing. At clinical follow-up 3 months after surgery, the patient showed symmetric pain-free motion of both hips and was able to crouch. Radiography and CT showed both an osseous union and correct positions of the screws (Figs. 1D and 1E).
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The prevalence of iatrogenic injury to the sciatic nerve with a fracture of the acetabulum is reported to be 56% [2] and 0.3% for injury to the femoral nerve [1] using an open approach. Crowl and Kahler [8] described closed reduction and percutaneous fixation of anterior column acetabular fractures. None of their patients experienced infection, significant blood loss, or iatrogenic neurologic or visceral injury.
We now report a minimal access approach for a mildly displaced juxtatectal transverse acetabular fracture that could not be fixed only by the percutaneous technique. Because the tectal part of the acetabular fracture line was orientated from left anterolaterally to posteromedially, a short ilioinguinal incision was made to avoid damaging the femoral neurovascular bundle and allow a safe computer-navigated screw placement perpendicular to the fracture.
The second craniolateral screw with its tip pointing toward the sciatic notch could be inserted percutaneously. Nevertheless, in an approach without intraoperative CT, the placement of the screw would have been difficult and potentially dangerous for the sciatic nerve because the distance from the near to the far cortex may be difficult to see.
The procedure was performed in a multifunctional imaging-guided therapy suite that integrates the technology and infrastructure for sterile imaging-guided surgery [6]. Performing this procedure would not have been possible in a conventional operating room without tomographic intraoperative imaging or a conventional CT suite where the open part of the procedure would not have been allowed for hygienic reasons.
The CT-navigated percutaneous acetabular fracture fixation allowed the patient mobilization with full motion starting the first postoperative day and partial weight-bearing for 6 weeks. In a conservative approach, the patient would have been immobilized with restricted motion for several weeks because of the risk of a secondary fracturedislocation.
In conclusion, the case we presented shows that the combination of minimally invasive percutaneous closed reduction and percutaneous fixation of a transverse acetabular fracture is technically feasible without endangering the femoral and sciatic nerves and can achieve an excellent clinical result. The interdisciplinary approach devised by surgeons and interventional radiologists and the integration of sophisticated imaging technology in a sterile operation theater enabled us to try a new approach for successful closed reduction and percutaneous fixation of an acetabular fracture and may offer the patient earlier mobilization.
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