Abstract Details
| Presented By: | Abraham, Christine |
| Affiliated with: | SFGH Biomechanical Testing Facility, Department of Orthopaedic Surgery |
| Authors: | Christine Abraham, John Rodriguez, Jenni Buckley, Shane Burch, Mohammad Diab |
| From: | University of California at San Francisco |
Title
Abstract
Introduction
Adults with unresolved developmental dysplasia of the hip often warrant Periacetabular Osteotomy (PAO). Making the correct osteotomies and finding the “ideal” position of the acetabulum is difficult, even for the experienced surgeon.4 Due to its 3-D nature, need for precision, and limited visualization of the surgical site, the PAO procedure is a good candidate for Computer Assisted Surgery (CAS). The utilization of improved imaging hardware and intra-op navigation systems has the potential to reduce complication rates and lessen the learning curve in the inexperienced surgeon.1 Previous studies have used navigation systems for guidance but as of yet,2,3 modeled PAO surgical plans have not been combined with intra-op navigation.
Methods
Five fresh-frozen human cadaveric pelves were included. Microbeads were implanted in the acetabulum to provide a measure of error. Pre-op CT scans were obtained on a clinical scanner (1 mm slice) and imported into an image-processing program (Mimics, Materialise, Belgium).
Pre-op plans were developed and imported into a navigation system (Treon, Medtronic, CO). With the simulated image as the reference, the navigation system was used to direct the osteotomies and manipulate the fragment according to the plan.
A 3-D image (O-arm, Medtronic, CO; 1 mm slice) recorded the final position of the acetabular fragment. Pre and post-op CT scans were compared to evaluate accuracy.
Results
The error between the post-op PAO scans and the pre-op plan was small relative to expected values. Mean error of the osteotomies was 1.97 ± 0.73 mm for the iliac cut. The mean difference between post-op and pre-op plan CE angle was 4.9 ± 6.0°, with 3 of the specimen having a CE within 1° accuracy. The mean rotational error in positioning of the acetabulum was 2.39 ± 1.01 mm.
Conclusions
The major challenges of the technique include consistency, intra-op time, and ease of use. The inconsistency in CE accuracy was attributed to the manual challenges of stabilizing the acetabulum without soft tissue and ligament support. Given the accuracy of this pilot study, CAS with pre-op planning and surgical navigation shows promise in improving the accuracy of PAO surgeries.
References
1. DiGioia Clin Orthop Relat Res 2007.
2. Langlotz Comput Aided Surg 1997.
3. Mayman Comput Aided Surg 2002.
4. Peters J Bone Joint Surg Am 2006.