Amir Putra Md Saad

Three-Dimensional Morphometric Study of the Trapezium Shape of the Trochlea Tali

The trapezium shape of the talar dome limits the use of 2-dimensional plain radiography for morphometric assessment because only 2 of the 4 required parameters can be measured. We used computed tomography data to measure the 4 morphologic parameters of the trochlea tali: anterior width, posterior width, trochlea tali length, and angle of trapezium shape. A total of 99 subjects underwent computed tomography scanning, and the left and right talus bones were both virtually modeled in 3 dimensions. The 4 morphologic parameters were measured 3 times each to obtain the intraclass correlation, and analysis of variance was used to check for any significant differences between the repeated measurements. The average intraclass correlation coefficient for the measurements for 2 to 3 trials was 0.94 ± 0.04. Statistical analyses were performed on the data from all 198 talus bones using SAS software, comparing male and female and left and right bones. All 4 morphometric values were greater in the male group. No significant differences were found between the left and right talus bones. A strong positive correlation was observed between the trochlea tali length and the anterior width. The angle of trapezium shape showed no correlation with the other 3 parameters. The measurements were compared with the dimensions of the current talar components of 4 total ankle arthroplasty implants. However, most of them did not perfectly match the trapezium shape of the talus from our population. We successfully analyzed the trapezium shape of the trochlea tali using reliable virtual 3-dimensional measurements. Compared with other published reports, our study showed a relatively smaller dimension of the trochlea tali than the European counterparts.

Wear Prediction on Total Ankle Replacement : Effect of Design Parameters

This book develops and analyses computational wear simulations of the total ankle replacement for the stance phase of gait cycle. The emphasis is put on the relevant design parameters. The book presents a model consisting of three components; tibial, bearing and talar representing their physiological functions

Effect of Design Parameter Towards Wear Generation

Wear performance was affected by several factors to contribute towards wear generation. Prospect of minimize wear is needed further study by using optimize design parameter. Inevitability to optimize the design is to improve the understanding of reducing wear in human ankle joint. Change in implant dimension has been suggested, may result in better implant lifespan. The effect of design parameter towards wear generation were analysed the thickness and radial contact of meniscal bearing.

Contact Pressure of Total Ankle Replacement (TAR)

Three-dimensional (3D) models of a right ankle TAR have been created to represent Bologna-Oxford (BOX) TAR model. Finite element analysis of ankle stance phase of gait cycle was developed to simulate the static response behaviour and extract the data in determining the contact pressure on contact surface of the bearing and talar components. Sliding distance was determined by predominate motion of plantar/dorsi flexion of ankle stance phase gait cycle. Validity of contact analysis was conducted to make sure consistent, accurate, and therefore dependable procedures.

Wear of Total Ankle Replacement (TAR)

Computational wear simulation of TAR were developed using the Archard’s wear model. Wear rate is the ultimate performance indicator of wear. The parameter such as ankle joint loading and kinematics were used in determining wear rates. Historically, wear performance was assessed by experimental means of clinical and physical simulators. Therefore, this present studies was used the finite element method to predict wear of TAR with adaptive re-meshing technique. The wear sensitivity test was conducted to determine the wear update interval and converge at 0.5 million cycles for update interval.