A 3D computer graphics-based biomechanical model of the knee joint for the design and evaluation of total knee replacements (3/3)
Date Issued
2004-07-31
Date
2004-07-31
Author(s)
DOI
922320B002060
Abstract
Total knee arthroplasty has been the main choice of treatment for advanced degenerative knee
osteoarthritis over the last few decades, aiming at effective relief of pain, recovery of functional
mobility and providing sufficient stability. Despite the excellent long-term survivorship of current
total knee designs, there are a number of improvements that can be made, as well as potential
problems that may emerge in the future. Also, it is noted that good survivorship does not
necessarily imply satisfactory functional recovery. Therefore, in developing a new prosthesis, it is
essential to ensure the functional performance that the prosthesis may bring to the patient, apart
from improving its wear resistance and fixation in the body.
Complete knowledge of the function and biomechanics of the natural knee is critical in
developing a new total knee prosthesis that is aimed at improving the patient’s function. Due to
ethical considerations and technical limitation, direct measurement of internal forces in the knee
joint is difficult. In vitro experiments with cadavers thus have been used in the literature to study
knee biomechanics. However, it has been agreed that it is difficult to simulate dynamic
physiological loading in an in vitro experimental setting. Therefore, a three-dimensional computer
graphics-based model of the knee joint will be useful for the design and pre-clinical testing of total
knee replacements. It is also important for the evaluation and rehabilitation of patients
post-surgery. It is the purpose of the present project to establish such a model. The project was
carried out in three stages (years).
During the first year, a 3D computer graphics-based biomechanical model of the knee joint
was developed. The model was customized to specific subjects with their own CT or MRI data.
Simulation study of knee biomechanics during single joint movement (mobility, stability and
muscle strength tests) has also been performed and the results validated with experimental data.
During the second year, the 3D computer graphics-based biomechanical model of the knee
joint that was developed in the first year has been used to simulate total knee replacement surgeries
for the study of the effects of TKR designs (PCL retaining/substitution) on the biomechanical
performance of the knee during functional activities. The results of the study showed that the
stability of knee significantly reduced after surgery as the stabilization structures such as ligaments
and articular surfaces were removed or changed. Existing total knees were unable to reconstruct
the normal stability of the joint. Therefore, muscles are important for knee stability during
movement. Since the ACL was removed, normal knee kinematics cannot be recovered simply by
total knees without any substituting mechanism for the ACL. Both types of TKR produced passive
knee kinematics that were very different from normal. The removal of the ACL reduced
significantly the stability of the knee but could be recovered by hamstrings actions with 30-50%
level of its maximum force. Responses of the joint with hamstrings action were similar for the two
types of TKR and the ACL-deficient knee. It seems that reconstruction of the ACL function maybe a consideration in future TKR designs.
The 3D computer graphics-based biomechanical model of the knee joint developed in the first
year has been incorporated into an existing lower limb model developed by the prime investigator.
It was used to simulate on the biomechanical performance of the knee during functional activities.
The results of the study showed that the mechanical performance of ligaments and articular surfaces
were in agreement with the patterns reported in the literature.
The results of this 3-year study will be useful for the design and pre-clinical testing of total
knee replacements. It is also helpful for the evaluation and rehabilitation of patients post-surgery.
Subjects
knee biomechanics
total knee replacement
computer model
gait analysis
Publisher
臺北市：國立臺灣大學醫學工程學研究所
Type
report
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