Session VII - Polytrauma
Sat, 10/9/04 Polytrauma, Paper #42, 11:23 am
Value and Operative Consequences of Intraoperative 3-D Imaging at Intraarticular Fractures -Analysis of 122 Patients
Purpose: Identification and interpretation of articular steps and hardware misplacement remains a crucial step during joint reconstruction. Long-term outcome correlates with initial reposition and adequate fixation. Two-dimensional intraoperative imaging modalities, such as a c-arm, are not as useful as three-dimensional image modalities and are limited in analyzing complex anatomic shapes, such as those of the calcaneus, acetabulum, pilon tibiale, or tibial plateau. Intraoperative computed tomography (CT) is rare and costly. Often postoperative CT becomes the standard method used for decision making and postoperative analysis. Correctional re-operations are necessary if significant articular steps or misplacements are identified afterwards. A new mobile three-dimensional c-arm (Iso-C3D, Siemens) provides multiplanar image reconstructions, enabling direct intraoperative control of articular steps and implant misplacement and enabling immediate operative correction in the same procedure. We studied the value and the resulting intraoperative decisions based on the Iso-C3D imaging in 122 different joint fractures on different anatomic regions within the last year at our clinic.
Methods: Between January and November, 2003, 122 different joint fractures were intraoperatively scanned with the Iso-C3D. The following fracture locations were analyzed: 19 ankle, 13 forefoot, 20 calcaneus, 23 pilon tibiale, 19 tibial plateau, 11 wrist, 9 spine, and 8 pelvis. Positioning was done on a full-carbon table (VIWAS, Maquet). Multiplanar reconstructions were obtained from 100 fluoroscopic images that the Iso-C3D provides during one automatic scan protocol. The scans were performed intraoperatively directly after open reduction and internal fixation of articular joint lines was performed. Initial conventional c-arm imaging was done in all cases. Surgeons were able to analyze joint reconstructions and screw misplacement in multiplanar reconstructions intraoperatively and compare them with conventional c-arm images. Decisions about remaining articular steps and implant misplacements were made and, if necessary, operative corrections were performed. On the basis of the surgeon's decision, postoperative CT scans were performed. Quality and congruency compared with Iso-C3D images was assessed by the specific surgeon. The data about intraoperative use, users, indications, set-up time, preparation, and resulting intraoperative decisions were analyzed.
Results: A total of 122 intraoperative Iso-C3D scans were performed. Five scans were not useable because of artifacts. The system crashed twice, and 3 patients moved during the scan. Finally, 112 cases could be analyzed. Scanning procedure time itself took 120 seconds. Radiation time was 20 sec/case. Set-up time, including positioning of the system, took 190 sec. (range, 150 to 840). Time for analyzing the multiplanar images on the Iso-C3D monitor took 340 sec (range, 126 to 500). In 17 clinical cases (15%) a direct intraoperative correction was performed by an implant change (8%) or correction of reduction (7 %), caused by articular steps >2 mm, screw, or k-wire misplacement. In all those cases, conventional c-arm images did not reveal the significant step or misplacement. The correction decisions were all based on the Iso-C3D imaging in those cases. In another eight cases (7%) significant steps or misplacements were identified in c-arm images and confirmed in the Iso-C3D images. One subchondral k-wire seemed to be identified intra-articularly on c-arm images, while the multiplanar images revealed exact subchondral placement. Postoperative CT scans were performed in 47% of all cases; they confirmed the Iso-C3D results and were congruent. Quality was considered sufficient and good in all cases. No significant intraarticular step or hardware misplacement was missed with the Iso-C3D.
Discussion/Significance: Two-dimensional intraoperative imaging does not always allow for precise identification of all articular joint steps and hardware misplacements. Minimally invasive procedures combined with closed reduction especially require exact anatomic reduction. Intraoperative visualization remains problematic, and conventional c-arm images are not always sufficient. An intraoperative CT is costly, not mobile, and very rare. The Iso-C3D provides three-dimensional intraoperative images for the detection of remaining intraarticular steps and implant misplacements. Direct intraoperative decisions and corrections become possible. Potentially, postoperative CT to identify steps and misplacements can be avoided. However, necessary set-up time, including scanning and preparation of the multiplanar images, as well as specially trained personnel are still necessary for the intraoperative use of this new imaging device. Extra costs for postoperative CT scans and re-operations have to be compared with initial cost and costs of maintenance of the Iso-C3D.