Background: Periacetabular osteotomy (PAO) is the treatment of choice for younger patients with developmental hip dysplasia. The procedure aims to normalize the joint configuration, reduce the peak-pressure, and delay the development of osteoarthritis. The procedure is technically demanding and no previous study has validated the use of computer navigation with a minimally invasive transsartorial approach. Methods: Computer-assisted PAO was performed on ten patients. Patients underwent pre- and postoperative computed tomography (CT) scanning with a standardized protocol. Preoperative preparation consisted of outlining the lunate surface and segmenting the pelvis and femur from CT data. The Biomechanical Guidance System was used intra-operatively to automatically calculate diagnostic angles and peak-pressure measurements. Manual diagnostic angle measurements were performed based on pre- and postoperative CT. Differences in angle measurements were investigated with summary statistics, intraclass correlation coefficient, and Bland–Altman plots. The percentage postoperative change in peak-pressure was calculated. Results: Intra-operative reported angle measurements show a good agreement with manual angle measurements with intraclass correlation coefficient between 0.94 and 0.98. Computer navigation reported angle measurements were significantly higher for the posterior sector angle ((Formula presented.), (Formula presented.)) and the acetabular anteversion angle ((Formula presented.), (Formula presented.)). No significant difference was found for the center-edge ((Formula presented.)), acetabular index ((Formula presented.)), and anterior sector angle ((Formula presented.)). Peak-pressure after PAO decreased by a mean of 13% and was significantly different ((Formula presented.)). Conclusions: We found that computer navigation can reliably be used with a minimally invasive transsartorial approach PAO. Angle measurements generally agree with manual measurements and peak-pressure was shown to decrease postoperatively. With further development, the system will become a valuable tool in the operating room for both experienced and less experienced surgeons performing PAO. Further studies with a larger cohort and follow-up will allow us to investigate the association with peak-pressure and postoperative outcome and pave the way to clinical introduction.

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International Journal of Computer Assisted Radiology and Surgery
Erasmus MC: University Medical Center Rotterdam

De Raedt, S., Mechlenburg, I., Stilling, M., Rømer, L., Murphy, R.J. (Ryan J.), Armand, M. (Mehran), … Søballe, K. (2018). Reliability of computer-assisted periacetabular osteotomy using a minimally invasive approach. International Journal of Computer Assisted Radiology and Surgery, 1–8. doi:10.1007/s11548-018-1802-y