Orthopaedic Biomechanics

We investigate joint shape, musculature, and associated biomechanics as they change due to injury or disease and how we can improve interventions to preserve or restore joint health.


Our work seeks to link outward manifestations of pathology (e.g. functional deficits) with internal abnormalities (e.g. bone deformity, muscle dysfunction). We study how abnormal joint shape or altered muscles affect movement patterns and how these factors are collectively associated with osteoarthritis (OA) development. Using in-vivo motion capture technology, we measure movement biomechanics and how they are affected by OA or pre-cursors such as hip dysplasia. We combine in-vivo biomechanics with medical imaging (e.g. CT and MRI) to make subject-specific musculoskeletal models that can quantify muscle forces that are not measurable in the laboratory. By applying these tools in interdisciplinary teams, we seek to improve surgical interventions, inform targeted rehabilitation, and enhance quality of life for people facing OA.

Faculty Investigators

Michael D. Harris, PhD

Current Members

Brecca Gaffney, PhD
Postdoctoral Research Scholar
Molly Shepherd
Research Assistant, BS Student-Mechanical Engineering
Ke Song, MS
PhD Candidate, Mechanical Engineering and Materials Science

Past Members

Julia Blumkaitis (Research Technician)
Jacqueline Foody, BS (Research Assistant, Biomedical Engineering Student)
Carly Krull (BS Student, Biomedical Engineering)
Hannah Steele (DPT Student and Research Assistant)
Lauren Westen, DPT (DPT Student and Research Assistant)

Current Research Studies

Bone-Muscle Relationships in Developmental Dysplasia of the Hip
Funding Source: NIH, National Institute of Arthritis and Musculoskeletal Skin Diseases (K01AR072072)

Revised model of DDH that considers bone-muscle relationships in the pathway to symptom development and structural damage.

This project focuses on muscle performance and joint mechanics in patients with developmental dysplasia of the hip (DDH). DDH is a major etiological factor in hip OA, especially in adolescents and young adults. The common paradigm of DDH mechanics is that bony deformities of the acetabulum (hip socket) and femur fail to provide a congruent surface for joint loading, which instigates metabolic and mechanical injury leading to OA. We are investigating a revised model of DDH that incorporates abnormalities in the surrounding muscle geometry, movement patterns, and loading. Our studies are providing new knowledge about how relationships between abnormal bone and muscle may be important factors in DDH symptomatology and joint damage.

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Muscle Performance after Periacetabular Osteotomy for DDH
Funding: NIH, National Institute of Arthritis and Musculoskeletal and Skin Diseases (P30AR057235) (P30AR074992)

Hip preservation surgeries for DDH, like the periacetabular osteotomy, can relieve pain for many patients, but many others development additional symptoms and long-term results do not demonstrate an effective offset of OA. In this project, we quantify the effect of hip preservation surgeries on muscle performance. By quantifying muscle atrophy, mechanical moment arms, neuromuscular activation patterns, joint reaction forces, functional strength, and movement patterns we hope to clarify why some patients respond well to surgery and others do not, as well as inform optimized surgical techniques and post-surgical rehabilitation.

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Statistical Shape Modeling of Femurs in DDH
Funding Source: Washington University

DDH diagnosis and treatment often focuses on the shallow acetabulum. However, it is common for the femur of dysplastic hips to also have bony deformities. These deformities might have a strong influence on loading and damage within the hip, but the optimal surgical correction for femurs in cases of DDH is unknown. While 2D measures of femoral deformity exist, an objective 3D measurement of femoral shape variations in dysplastic hips has not been established. We are using statistical shape modeling to describe 3D morphological variations among femurs in patients with DDH, which can then assist surgeons treating patients with challenging cases of dysplasia.

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Quantification of Bone Shape Variability, Whole-Body and Joint level Biomechanics of Hip Dysplasia
Funding Source: L’Oréal USA For Women in Science Fellowship (PI – Gaffney)

This project is the first to investigate the neuromuscular control in patients with DDH. An innovative combination of surface electromyography (sEMG), motion capture, and musculoskeletal modeling will provide significant empirical evidence regarding factors beyond bony abnormalities that contribute to detrimental loading within the dysplastic hip. In addition, this study is also investigating loading on other joints throughout the body (e.g. low-back) during biomechanically challenging tasks. Prior biomechanical analyses of this population are centered on hip mechanics during low-level tasks, that likely are not challenging enough to encompass all pain avoidance movement strategies adopted by this population. Furthering the understanding of how neuromuscular control patterns contribute to loading patterns of the hip and low back will help improve the efficacy of rehabilitation for these young individuals trying to maintain a long-term active lifestyle.

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