Dissertation
An investigation on the three dimensional mechanical characteristics of the ankle and subtalar joints
Doctor of Philosophy (Ph.D.), Drexel University
Oct 1989
DOI:
https://doi.org/10.17918/00008327
Abstract
The general objective of this study was to investigate the in-vitro, coupled, three dimensional mechanical characteristics of the human ankle joint complex and to identify the changes in these characteristics following injury to the ligaments. The investigation consisted of three main parts: In the first part, the three dimensional kinematic characteristics of the ankle and subtalar joints were studied. In the second part, the three-dimensional load-displacement and the flexibility characteristics of the intact ankle joint complex were determined. Finally, in the third part, the effects of injuries to the lateral collateral ligaments on the flexibility characteristics of the ankle were identified through serial sectioning of the individual ligament. The experiments were performed on thirty one amputated lower limbs. The main components of the test apparatus consisted of a frame to which the tibia was rigidly fixed; a system of six pneumatic actuators for applying controlled loads to the calcaneus, and a kinematic data acquisition system for measuring the motion of the articulating bones (calcaneus and talus). The testing procedure consisted of two experiments. In the first experiment, which was conducted on the intact specimen, the external loads were applied to the calcaneus in small increments and the corresponding three dimensional positions of the moving parts ( the talus and the calcaneus ) were recorded through a three dimensional position data acquisition system. In the second experiment, the procedure described above was repeated after sectioning of selected ligament/s. Analysis of the data consisted of three major parts. In the first part, the three dimensional kinematic characteristics of the ankle and subtalar joints were determined. The first step in this analysis consisted of determining the relative position and incremental displacement between the articulating bones from the measurement of the coordinates of points on the moving bones ( talus and calcaneus). From these data, the joint parameters, which were used to describe the relative position between the bones were calculated. The relative, incremental displacements between any two of the articulating bones were described through the screw axis parameters. From these data the following kinematic characteristics of the ankle joint complex were determined 1) range of motion; 2) kinematic coupling at each joint; 3) the contribution of the ankle and of the subtalar joint to the motion between the calcaneus and the shank. In the second part of the analysis, the coupled nonlinear, three dimensional load-displacement and flexibility characteristics of the ankle joint complex were determined. An incremental linearization procedure was used for this purpose. The third part consisted of a statistical analysis to determine the effects of sectioning of various ligaments on the load-displacements and flexibility characteristics of the ankle joint complex. Specifically, paired t-tests were employed to compare these characteristics prior to and following sectioning of selected ligaments. Some of the main findings from each of the three parts were: From the results of the kinematics investigation it was concluded that: 1) Large kinematic coupling values are present at the ankle complex in inversion/eversion and in internal rotation/external rotation. However, only a slight amount of coupling was observed to occur in dorsiflexion/plantarflexion.; 2) Neither the ankle joint nor the subtalar joint are acting as ideal hinge joints with a fixed axis of rotation.; 3) Motion of the ankle complex in any direction is the result of rotations at both the ankle and the subtalar joints. However, the contribution of the ankle joint to dorsiflexion/plantarflexion of the ankle complex is larger than that of the subtalar joint and the contribution of the subtalar joint to inversion/eversion is larger than that of the ankle joint. Moreover, the ankle and the subtalar joints have an approximately equal contribution to internal rotation/external rotation movements of the ankle complex. From the analysis of the normal flexibility characteristics of the ankle complex, it was evident that the complex exhibit highly coupled flexibility and load - displacement characteristics. It was further concluded that the ankle joint complex is the most flexible in the neighborhood of the unloaded, neutral position and that all the flexibility coefficients of the structure decrease rapidly towards the extremes of the range of motion. From the study of the injured ankle, it was concluded that the three dimensional flexibility characteristics of the ankle joint complex are strongly influenced by damage to the lateral collateral ligaments. Furthermore, it was found that each type of ligament injury produced unique and identifiable changes in the flexibility characteristics of the ankle. These unique changes can be used to discriminate between the different types of ligament injuries, and can serve as the basis for developing a quantitative diagnostic technique for ankle ligament injuries.
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Details
- Title
- An investigation on the three dimensional mechanical characteristics of the ankle and subtalar joints
- Creators
- Jie Chen - Drexel University, Mechanical Engineering (and Mechanics) (1970-2026)
- Contributors
- Sorin Siegler (Advisor) - Drexel University, Mechanical Engineering (and Mechanics) (1970-2026)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xx, 131 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Mechanical Engineering (and Mechanics) (1970-2026); Drexel University
- Other Identifier
- 991021888880404721