Fast and Automatic Periacetabular Osteotomy Fragment Pose Estimation Using Intraoperatively Implanted Fiducials and Single-View Fluoroscopy

Unmet Need
Developmental dysplasia of the hip (DDH) is the most common developmental hip deformity in children, and the most common single cause of osteoarthritis of the hip in young and older adults. This condition occurs when there is insufficient coverage of the femoral head by an excessively shallow acetabulum (hip socket). Periacetabular osteotomy (PAO) is a common surgical procedure to treat DDH by reorienting the hip joint for increased femoral head coverage. Current surgical methodology requires a clinician to measure coverage of the femoral head intraoperatively via the use of a 2D fluoroscopic image. Accurate and consistent mental interpretation of fluoroscopy to determine the position and orientation of acetabular bone fragments in 3D space is difficult and time consuming. Consequently, the adoption of more automated techniques to measure femoral head coverage could improve the efficiency of PAO surgeries.  

Technology Overview
The inventors have developed a fast, automated method to compute the pose of PAO fragments to enhance intraoperative x-ray navigation. In this approach, two constellations of metallic ball-bearings (BB) are injected to map the patient’s acetabular fragment and pelvis fragment. The 3D locations of each BB are reconstructed using fluoroscopic views and 2D/3D registrations to a preoperative CT scan of the pelvis. This approach can estimate the relative pose of the acetabular fragment to the pelvis fragment by estimating the movement of the two BB constellations using a single fluoroscopic view taken after osteotomy and fragment relocation. BB detection and inter-view correspondences are automatically computed throughout the processing pipeline. Importantly, when tested in cadaver surgeries, this method demonstrated similar accuracy to other state of the art systems.

Stage of Development
The inventors have developed a working prototype and demonstrated its efficacy in cadaver surgeries.

Publications
Grupp, RB et al. Pose Estimation of Periacetabular Osteotomy Fragments with Intraoperative X-Ray Navigation. IEEE Transactions on Biomedical Engineering. May 2019. doi: 10.1109/TBME.2019.2915165

Grupp, RB et al. Fast and Automatic Periacetabular Osteotomy Fragment Pose Estimation Using Intraoperatively Implanted Fiducials and Single-View Fluoroscopy. ArXiv Preprint. October 2019. Arxiv:1910.10187
 

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