Whole Body & Joint-Level 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 centers on linking outward manifestations of pathology (e.g. functional deficits) with internal abnormalities (e.g. bone deformity, muscle dysfunction). Specifically, we study how alterations in joint geometry or the musculature affect movement patterns and how these factors are collectively associated with osteoarthritis (OA). Our research begins long before OA is evident and stretches into the late stages of the disease, as well as after surgical intervention (e.g. joint replacement). The major tools we use include in-vivo biomechanics, medical imaging and visualization, and musculoskeletal modeling. Using in-vivo motion capture technology, we measure movement biomechanics and how they are affected by OA or pre-cursors such as traumatic joint injury or developmental dysplasia. We combine in-vivo biomechanics with subject-specific 3D musculoskeletal models made from medical imaging (e.g. CT and MRI) to 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

Julia Blumkaitis (Research Technician)
Brecca Gaffney, PhD (Postdoctoral Research Scholar)
Ke Song, MS (PhD Candidate, Mechanical Engineering and Materials Science)
Lauren Westen, BA (DPT Student and Research Assistant)

Past Members

Hannah Steele (DPT Student and Research Assistant)
Carly Krull (BS Student, Biomedical Engineering)

Current Research Studies

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

In this project, we focus 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 the 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.

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

Statistical Shape Modeling of the Dysplastic Femur
Funding Source: Washington University

DDH is characterized by a shallow acetabulum that fails to cover and stabilize the femoral head. 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. This study uses statistical shape modeling to describe 3D morphological variations that are most common in the femurs of patients with DDH, which can then assist surgeons treating patients with challenging cases of dysplasia. Check out our latest abstract, presented at the 2018 Orthopaedic Research Society meeting.

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

Hip preservation surgeries for DDH, like the periacetabular osteotomy, can relive pain for many patients, but many others development additional symptoms and long-term results do not demonstrate an effective offset of OA. In this study, we seek to quantify the effect of hip preservation on muscle performance, which is not currently part of post-surgical assessment, and how it is altered at the time patients are cleared for return to full activity. 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.

Carbon Fiber Off-Loading Orthosis
Funding Source: NIH R41DK109731-01 (PI = Michael Dailey, Dequan Zou)

This project further develops a Carbon Fiber Composite (CFC) ankle foot orthosis (AFO) designed to off-load plantar pressures and optimize patient function through maximizing plantarflexor power production. During Phase I, we are determining the effects of varying design characteristics of CFC off-loading AFOs. We will refine and create new FEA models and algorithms that predict the appropriate brace design given patient characteristics including patient baseline functional abilities. In a future Phase II project, we will refine the algorithm for patients with various diagnoses and presentations to ensure the applicability across the spectrum of potential users and develop rapid fabrication techniques that integrate CAD/CAM technology to maximize brace durability, minimize error, and allow national and international CFC off-loading AFO distribution.