Optimizing PAO Correction
The goal of this project was to use discrete element analysis (DEA), a computational stress analysis technique, to understand how reorienting the acetabular fragment during periacetabular osteotomy (PAO) affects the contact mechanics of the dysplastic hip joint and how those mechanical changes influence patient outcomes.
Principal Investigators: Michael Willey, MD & Jessica Goetz, PhD
Co-Investigators: Holly Aitken, PhD; Dominic Rivas, BSE; Robert Westermann, MD
Funding: Orthopaedic Research & Education Foundation
Publications:
Aitken HD, Miller A, Rivas DJL, Tatum M, Westermann RW, Willey MC, Goetz JE. Radiographically successful periacetabular osteotomy does not achieve optimal contact mechanics in dysplastic hips. Clin Biomech. 2023;104:105928. doi: 10.1016/j.clinbiomech.2023.105928.
Aitken HD, Miller A, Rivas DJL, Westermann RW, Willey MC, Goetz JE. Providing a computationally derived, mechanically optimised target correction during preoperative planning can improve joint contact mechanics of hip dysplasia treated with periacetabular osteotomy. Hip Int. 2024;34(3):378-389. doi: 10.1177/11207000231212403.
Mechanical Contributions to 10-Year PAO Outcomes
This project aimed to use discrete element analysis (DEA), a computational stress analysis technique, to evaluate changes in contact stress in patients treated with periacetabular osteotomy (PAO) for hip dysplasia and correlate those changes with patient-reported clinical outcomes at a minimum 10-year follow-up.
Principal Investigators: Michael Willey, MD & Jessica Goetz, PhD
Co-Investigators: Holly Aitken, PhD; Dominic Rivas, BSE; Robert Westermann, MD; Todd McKinley, MD
Funding: Orthopaedic Research & Education Foundation
Publications:
Willey MC, Westermann RW, Glass N, Goetz JE, Aitken H, Fatemi N, Davison J, Miller A, Parker E, Fruehling C, McKinley TO. Risk factors for composite failure of hip dysplasia treated with periacetabular osteotomy: minimum 10-year follow up. J Am Acad Orthop Surg. 2022;30(8):e690-e702. doi: 10.5435/JAAOS-D-21-00535.
Aitken HD, Goetz JE, Glass NA, Miller A, Rivas DJL, Westermann RW, McKinley TO, Willey MC. Persistently elevated joint contact stress after periacetabular osteotomy is associated with joint failure at minimum 10-year follow-up. J Orthop Res. 2024;42(12):2773-2783. doi: 10.1002/jor.25935.
Contact Mechanics in Non-Operative Dysplastic Contralateral Hips
The aim of this project is to use discrete element analysis (DEA) to calculate contact stress in the surgically untreated contralateral hip in individuals that underwent unilateral periacetabular osteotomy (PAO) for treatment of hip dysplasia. Relating this contact stress information with patient reported outcomes we hope to determine if elevated contact stress may serve as a computational biomarker for future development of osteoarthritis in these hips.
Principal Investigators: Michael Willey, MD & Jessica Goetz, PhD
Co-Investigators: Dominic Rivas, BSE & Holly Aitken, PhD
Funding: Arthritis Foundation
Publications:
Rivas DJL, Goetz JE, Glass NA, Aitken HD, Kochuyt AS, Willey MC. DEA-computed contact stress as computational biomarker for OA development in the untreated contralateral hip of individuals that underwent unilateral PAO to treat hip dysplasia. 71st Annual Meeting of the Orthopaedic Research Society, March 27-31, 2026, Charlotte, North Carolina. Paper #50, Paper Presentation Session 10: Structural Hip Deformity.
Improving Understanding & Evaluation of Dysplastic Hip Coverage
This collection of projects focuses on understanding of how 2D radiographic measurements relate to 3D hip coverage, and on development of automated and semi-automated techniques to quantify 2D & 3D coverage of dysplastic hips. Digitally reconstructed radiographs and 3D surface models are used in combination to develop these relationships.
Key Investigators: Jessica Goetz, PhD; Holly Aitken, PhD; Dominic Rivas, PhD; Joshua Holt, MD; Michael Willey, MD; Stuart Weinstein, MD
Publications:
Rivas DJL, Weinstein S, Tatum M, Aitken HD, Ford A, Dempewolf S, Willey MC, Goetz JE. Radiographically apparent acetabular sourcil landmarks are created by comparable regions of the pelvis with extraarticular bone variably confounding estimates of joint coverage. Clin Orthop Relat Res. 2025;483(2):343-358. doi: 10.1097/CORR.0000000000003268.
Aitken HD, Goetz JE, Sailer WM, Rivas DJL, Farnsworth CL, Upasani VV, Holt JB. Three-dimensional assessment of subchondral arc and hip joint coverage angles in the asymptomatic young adult hip. Clin Anat. 2025;38(8):873-885. doi: 10.1002/ca.24221.
Aitken HD, Goetz JE, Sailer WM, Rivas DJL, Petrachaianan K, Glass NA, Willey MC, Holt JB. Dysplastic hips in young adults demonstrate different relationships between acetabular coverage, joint congruity, and contact mechanics than normal hips. J Orthop Res. 2025;43(11):2009-2022. doi: 10.1002/jor.70048.
Preclinical Model of Young Adult Hip Dysplasia
This work aims to develop a skeletally mature preclinical model of hip dysplasia that can be used for systematic studies of research questions that cannot be ethically or effectively address with human studies. The model has previously been established for developmental dysplasia of the hip in young children, and is being extended to the context of skeletal maturity.
Key Investigators: Jessica Goetz, PhD, Doug Fredericks; Michael Willey, MD; Josh Holt, MD; Animal Research Surgicenter
Publications:
Fredericks DC, Rivas DJL, Cruse DC, Petersen EB, Holt JB, Willey MC, Goetz JE. Progressive degenerative cartilage changes with persistence of dysplastic deformity in rabbit hips. ORS 2026 Annual Meeting. March 27-31, 2026. Charlotte, NC. Poster #415: PS1-013 Hip-Structure, Function & Mechanics.