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Updated: Aug 7, 2026
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Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion
Published on: April 11, 2018
Validation of the soft tissue restraints in a force-controlled knee simulator
M van Houtem1, R Clough, A Khan
1Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, University College London, Stanmore, UK.
Summary
Simulating knee joint soft tissue restraints in force-controlled simulators is crucial for accurate total knee replacement testing. Using stiff springs closely mimics anterior-posterior motion, but a compromise is needed for optimal results.
Area of Science:
- Biomedical Engineering
- Orthopedic Biomechanics
- Medical Device Testing
Background:
- In vitro testing of total knee replacements (TKRs) is essential for predicting in vivo wear.
- Force-controlled simulators require accurate simulation of soft tissue restraints, including the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL).
Purpose of the Study:
- To assess the accuracy of soft tissue restraint simulation in a force-controlled Stanmore knee simulator.
- To evaluate the effectiveness of spring elements in replicating the restraining forces of the ACL and PCL.
Main Methods:
- Human cadaver knee joints were tested under the ISO Standard Walking Cycle.
- Kinematics were monitored with intact ligaments, after ACL and PCL resection, and when simulated by anterior and posterior springs of varying stiffness (7.24 N/mm and 33.8 N/mm).
Main Results:
- Ligament resection significantly increased anterior-posterior motion and rotation compared to intact knees.
- Hard springs (33.8 N/mm) positioned anteriorly and posteriorly restored near-normal anterior-posterior motion after ligament resection.
- Posteriorly placed hard springs reduced rotational displacements in all tested conditions.
Conclusions:
- Simulating ACL and PCL restraints with springs in force-controlled simulators involves a compromise.
- Intermediate stiffness springs may offer greater accuracy in replicating native knee joint kinematics for TKR testing.
