Session VII Pelvis and Acetabulum

Use of Intraoperative Fluoroscopy to Evaluate the Presence of Intra-Articular Hardware and Fracture Reduction in Acetabular Surgeries

Brent Norris, MD, David H. Hahn, MD, Michael J. Bosse, MD, Stephen H. Sims, MD, James F. Kellam, MD

Dept. of Orthopaedic Surgery, Carolinas Medical Center, Charlotte, NC

A cadaver model was tested to validate a clinical observation that the image could assist the surgeon in the assessment of intra-articular screw placement and to confirm the observation that: "If it (the screw) is out (of the joint) in any view, it's out."

A prospective clinical trial was conducted between October 1994 and November 1995 to evaluate the efficacy of intraoperative fluoroscopy during acetabular surgery in two realms; the determination of intra-articular hardware penetration and the assessment of fracture reduction. Thirty-eight patients with 40 acetabular fractures were treated by three pelvic surgeons. A radiolucent operating table and a 9-inch fluoroscopy unit were employed for the surgeries. Intraoperatively, AP, oblique and lateral pelvic images were obtained after fracture reduction and provisional fixation and at the conclusion of the case. A "hard copy" of the intraoperative lateraI image was obtained for the radiographic record. Postoperatively, standard AP and oblique radiographs were obtained on all patients to assess reduction, and CT scans were obtained on all but four patients to evaluate fracture reduction and hardware placement. The intraoperative fluoroscopic findings were compared to the postoperative studies to answer the protocol questions.

Complete data for analysis were available for 30 patients with 32 fractures. The three pelvic surgeons and an orthopaedic trauma fellow independently reviewed the radiographs and graded fracture reduction and the presence or suspicion of intra-articular hardware penetration. Using the postoperative AP and Judet radiographs and the lateral fluoroscopic view obtained intraoperatively, the surgeons thought that 95% of the cases had views adequate to assess intraoperative hardware penetration and fracture reduction. Articular reduction was graded as anatomic in 74%, satisfactory in 23% and unsatisfactory in 3% of the cases. Subsequent CT scans altered this interpretation to 56% anatomic, 37% satisfactory and 4% unsatisfactory.

Hardware joint penetration was noted in 5% of the cases. No intra-articular hardware penetration was noted in 84% of the cases and was indeterminate in 11% of the cases. Reasons for grading radiographs as indeterminate included bilateral acetabular surgery, morbid obesity and inadequate radiographic technique. None of the indeterminate responses were noted to have hardware in the joint on subsequent CT scan evaluation. Additionally CT scan confirmed the reading of no intra-articular hardware on all patients. The CT scan identified two false positive readings in which the plain radiograph was thought to have metal in the joint because of the placement of spring plates. One case identified on plain radiographs as having metal in the joint was confirmed by CT scan. This patient was evaluated by fluoroscopy intraoperatively, and the intra-articular presence of a screw was missed secondary to an error in x-ray evaluation by the operating team. The patient required revision surgery.

The use of intraoperative fluoroscopy appears to provide the surgeon with the ability to judge the adequacy of the fracture reduction and the presence or absence of intra-articular metal. In the one case in the study in which the patient returned to the OR for screw removal, intraoperative reading of the film erroneously concluded that a screw later read by all reviewers as being intra-articular was, in fact, extra-articular. Compared to a previous series at our center in which 72 acetabular cases were reviewed and 6 patients were found to have intra-articular hardware, with 3 requiring reoperation, the use of operative fluoroscopy has reduced our incidence of joint penetration.