[100 CT-guided pelvic operations].

Abstract

PURPOSE OF THE STUDY: The authors present their 10-year experience with the computed tomography (CT) assisted insertion of implants in the sacroiliac (SI) region and acetabular region. Indications for these interventions and their detailed descriptions are reported. MATERIAL: A total of 98 patients, with the average age of 40.7 years and prevalence of men (70%), were treated. The most frequent cause of injury was a car accident, second in rank was fall from a height. Of these patients, 86 were followed up from 2 months to 3 years. METHODS: The surgical procedure was carried out in the CT department, in which conditions were provided to meet the criteria of an operating theatre. Computed tomography was used to plan the exact position of the implant and, during the procedure, to guide its precise insertion. These procedures required close cooperation of the surgeon and radiologist. A total of 73 CT-guided operations were performed on the SI region, using iliosacral screws or sacral rods. The operation was always preceded by surgery on the anterior pelvic segment. Iliosacral screws were also used in six patients operated on for pseudoarthrosis of the sacrum or chronic instability of the SI joint. The screws were also used in 19 patients who underwent surgical intervention in the acetabular region; in 14 cases it was for a fracture of the acetabular rim. All procedures were carried out by this minimal invasive technique. RESULTS: In all cases, correct insertion of the implant was achieved. There was only one serious preoperative complication due to the fact that the guidewire deviated from its planned direction without this being shown by CT scan. A late infectious complication following iliosacral screw application was recorded in one patient and, in another patient, a nut loosened on one side of the sacral rod. These implants, temporally immobilizing the SI joint, were removed at periods of 6 to 9 months after the operation. There was no case of secondary dislocation of the SI joint after the implant was removed. Complete bony healing of the fractures treated, including pseudoarthrosis, was achieved in all our patients. A comprehensive evaluation of the clinical results of CT-guided operations was difficult because of large inter-individual differences in the extent of pelvic injuries. DISCUSSION: CT-guided interventions are currently indicated predominantly for fractures of the sacrum or displacement of the SI joint up to a 15 mm distance. It is necessary to re-evaluate the extent of displacement after an exact reconstruction of the anterior pelvic segment and restoration of the anatomical conditions. The displacement in the posterior segment usually becomes markedly reduced. The simultaneous surgical treatment of both the anterior and posterior pelvic segments results in restoration of pelvic girdle continuity and maintenance of good stability of the pelvis. This permits early rehabilitation and mobilization of the patient. Other conditions indicated for CT-guided surgery include simple fractures of the acetabular rim with a distance between the fracture lines up to 7 to 10 mm, usually following hip dislocation, and simple oblique fractures of the acetabular columns. CONCLUSIONS: The CT-guided surgical procedure allows us to assess both the shape and course of fracture lines or distance between the injured structures. It also enables us to choose the optimal direction, in relation to these structures, for an implant to be inserted and to respect important anatomical structures in the surroundings. It helps us to determine the exact length of implants to be used. During the procedure, repeated CT scans facilitate checking the direction and position of both instruments and implants. In the closing phase of the operation, it is possible to assess closeness of the bones screwed together, the definitive placement of the implants and their reliable fixation. This method also permits to check whether a screw did not penetrate through the opposite cortical bone.