Research Activities


Advanced Mobility Modeling to Improve Function and Longer Term Transitional Care of Children with Orthopedic Disabilities

This project employs advanced modeling of the upper and lower extremities to improve function and longer-term transitional care of children with myelomeningocele, cerebral palsy, spinal cord injury, osteogenesis imperfecta (brittle bone disease) and planovalgus foot deformities. R4 will determine the relationship among joint forces, assistive devices, ankle arthroreisis and longer-term tissue level effects as they relate to pain and function.

  • Co-PI's
    • Brooke Slavens, Ph.D.
    • Gerald Harris, PhD, P.E.
  • Patient population
    • Cerebral Palsy (CP): 12
    • Myelomenginocele (MM): 12
    • Spinal Cord Injury (SCI): 12
    • Osteogenesis Imperfecta (OI): 12
    • Pes Planovalgus: 20

R4 Update: 2012 Annual Meeting

  • R4A UE Progress
  • R4A UE Accomplishments
  • R4A Challenges
  • Plans for Year 3

R4 2012 Annual Update (PowerPoint) (569.5 KB)

R4 Hypotheses

  1. Proximal upper extremity joint demands are significantly greater than distal joint demands during assisted mobility in children using walkers, crutches and wheelchairs
  2. Lower extremity joint demands (hip, knee, talocrural, and subtalar) in children with pes planovalgus are significantly reduced following subtalar arthroereisis

R4 Upper Extremity Assessment

  • 48 subjects who use walkers, Lofstrand crutches or wheelchair for mobility
  • 3D motion analysis with Vicon system
  • Upper extremity inverse dynamics model
  • Kinetic data (forces and moments) for shoulder, elbow and wrist
    • Vicon system
    • Instrumented mobility devices
    • Models
  • UE musculoskeletal model to investigate repetitive strain injuries and overuse syndromes

Diagram shows a upper extremity 3D inverse dynamics model. Picture shows an SIMM shoulder model.

R4 Aims

  1. Quantify upper extremity (UE) shoulder, elbow, and wrist joint dynamics during walker, crutch, and wheelchair mobility in 48 patients using 3D motion analysis and force sensing instrumented devices
  2. Quantify lower extremity (LE) hip, knee, talocrural, and subtalar dynamics in 20 patients using 3D motion analysis, fluoroscopic analysis, and force platforms
  3. Characterize upper and lower extremity joint loads during ambulation using a SIMM-based musculoskeletal modeling approach
  4. Employ functional calibration methods to derive subject-specific estimates of joint centers and axes of rotation based on geometric best fit principles
  5. Statistically evaluate upper and lower extremity study results using a series of data evaluation and modeling techniques in collaboration with the project biostatistician. Graphical methods of exploratory data analysis and two-sample tests (both non-parametric and parametric) are used along with logistic regression and discriminate analysis with selected metric subsets. The progression of joint demands and ambulatory changes associated with each patient population will be defined.

R4 Lower Extremity Assessment

  • 20 patients with planovalgus and
    surgical plan of subtalar arthroereisis
  • Radiological assessment
    • All views taken with subject in standing
      weight-bearing position
    • Foot positioning template
  • Concurrent quantitative and fluoroscopic gait analysis
  • Baseline vs. post-op
    • Presurgery
    • One year post surgery
    • Two years post surgery

Diagram of foot shows a schematic of the Milwaukee foot model.

An X-ray of a shod foot captured by a fluoroscopy system.

R4 Anticipated Timeline

Activity Year 1 Year 2 Year 3 Year 4 Year 5
Technical system setup and implementation Q1Q2Q3Q4
Inverse dynamics model development testing and integration Q1Q2Q3Q4 Q1Q2Q3Q4
Patient recruitment Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Subject testing of 48 children using assistive mobility devices and 20 children with pes planovalgus Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Administration and assessment of outcomes tools Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Musculoskeletal model development & testing Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Musculoskeletal model integration Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Quantitative data review ongoing power analysis and statistical analysis Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4
Research dissemination Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4 Q1Q2Q3Q4