Functional biomechanics in orthopaedics
One of our main areas of research is the in vivo mechanosensitivity of articular cartilage. I started this research at Stanford University in 2003 and have greatly expanded my research in this area over the past 10 years. We have achieved some very exciting results that confirm our previous findings in patients with knee osteoarthritis. In this study and other recent projects on the effects of marathon running, ultra-marathon running, bed rest and space flight, we have shown that the same blood markers of articular cartilage metabolism are sensitive to loading and unloading, but in different directions (publications in the American Journal of Sports Medicine, Osteoarthritis and Cartilage, among others). In addition, we have established an experimental framework to study the in vivo dose-response relationship between the magnitude of ambulatory load and load-induced changes in blood levels of articular cartilage biomarkers by systematically modulating the magnitude of ambulatory load. Currently, we explore the potential of using this dose-response relationship as a diagnostic marker for articular cartilage degradation processes in patients at high risk of developing early knee osteoarthritis.
In recent years, we have greatly expanded in addressing clinical research questions. Functional biomechanics is an important aspect in the development, treatment and rehabilitation of most orthopaedic conditions. However, the gold standard (optical method) is very time consuming and hence not widely used in clinical practice. The importance joint load during ambulation also regarding blood markers of articular cartilage metabolism was further emphasized by data obtained in our ongoing project. Motivated by the desire to capture large cohorts we have invested considerable time and effort in exploring and establishing inertial sensor methods in a clinical research environment. We address methodological aspects of inertial sensor-based gait analysis and their application in a clinical studies in patients with lumbar or cervical spinal stenosis, knee or hip osteoarthritis, and knee or hip arthroplasty. Most recently, we have explored the classification of orthopaedic conditions based on wearable sensor-based kinematic patterns. In the novel workflow, all patients complete wearable sensor analyses preoperatively and at predefined post- operative follow-ups as part of their routine clinical assessment.
In the last five years, we have established a multimodal and multi-level experimental approach for investigating asymptomatic and symptomatic rotator cuff tear. The novelty of this approach is to not only investigating differences in joint biomechanics between patient groups but also to assess the sensitivity of joint biomechanics to additional load as many daily activities entail additional load that can exaggerate differences between patients and play an important role in the aetiology and progression of rotator cuff tears. We further evaluate these associations in our current project involving in vivo, ex vivo and in situ experiments. Our results have already provided new insight into joint forces, kinematic compensation and load-induced changes in muscle activity linked to the symptoms and radiological findings in patients with rotator cuff tear. These results emphasize the large potential of our approach for better understanding the biomechanical implications of rotator cuff tear and contributing to improved (patient-specific) treatment.
