Whole Body & Joint-Level Orthopaedic Biomechanics

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


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). Using motion capture technology, we measure how people move and how those movements are affected by OA or pre-cursors such as traumatic joint injury or geometric deformities. We combine motion capture with computer models to quantify muscle forces that are not measurable in the laboratory. We also create subject-specific 3D models of bone and cartilage to measure joint geometry for early diagnosis of potential problems and better understanding of shape variations among people with and without joint problems. By applying these tools in interdisciplinary teams, we seek to improve surgical interventions, target rehabilitation, and enhance quality of life for people facing OA.

Faculty Investigators

Michael D. Harris, PhD

Current Members

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: Washington University

Developmental dysplasia of the hip (DDH) dramatically increases risk for early development of hip osteoarthritis (OA) in adolescents and young adults. In cases of DDH, abnormal development of the acetabulum (hip socket) and femur cause the hip joint to be less stable, which can lead to painful acetabular labrum tears and articular cartilage lesions. Without correction, this joint damage progresses to OA and may require total joint replacement. Pain and physical limitation are common symptoms in patients with DDH. However, the presentation, intensity and combination of symptoms do not always correspond with radiographic signs of bony abnormalities or soft-tissue damage. Factors beyond bony structure, such as muscle function, likely contribute to symptom onset and altered joint loading, but the role of muscle in DDH pathomechanics is not well understood. This project is the first to rigorously investigate the bone-muscle relationship as a factor in pathomechanics and symptomatology in patients with DDH. We use magnetic resonance imaging (MRI) and musculoskeletal models to compare hip muscle volumes and 3D muscle moment arms between patients with DDH and control subjects. This can help elucidate relationships between muscle alterations and the severity of bony abnormalities. We also examine how bone-muscle geometry in DDH influences strength and joint mechanics by using muscle strength tests and 3D motion capture to quantify hip movement and loading during activities of increasing biomechanical demand. Finally, we are using patient reported outcomes (PROs) to establish novel links between important realms of patient evaluation – laboratory measurement and clinical research. Ultimately, we seek coordinated surgical and nonsurgical approaches that optimize joint loading and balance muscle use to improve treatment and delay OA for patients with DDH.

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

Hip dysplasia 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. 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 create 3D models of femoral geometry in a population of dysplastic hips and then describe prevalence and morphological description of femur deformities for surgeons treating patients with challenging cases of dysplasia.

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.

Biomechanics Changes with Fatigue
Funding Source: Washington University

This pilot study examines how young adults change lower extremity movement patterns as they fatigue during running and cutting exercises. Fatigue is cited as a risk for injury, but it is not understood if patients with hip dysplasia and femoroacetabular impingement (FAI) change their movement with fatigue in such a way exacerbates pain and damage in the joint. By quantifying possible changes, we may be able to develop educational programs to promote healthy biomechanics and attenuate damage caused by hip dysplasia and FAI.