A detailed and validated three dimensional dynamic model of the patellofemoral joint

Akbar, M ; Sharif University of Technology | 2012

2812 Viewed
  1. Type of Document: Article
  2. DOI: 10.1115/1.4006403
  3. Publisher: 2012
  4. Abstract:
  5. A detailed 3D anatomical model of the patellofemoral joint was developed to study the tracking, force, contact and stability characteristics of the joint. The quadriceps was considered to include six components represented by 15 force vectors. The patellar tendon was modeled using four bundles of viscoelastic tensile elements. Each of the lateral and medial retinaculum was modeled by a three-bundle nonlinear spring. The femur and patella were considered as rigid bodies with their articular cartilage layers represented by an isotropic viscoelastic material. The geometrical and tracking data needed for model simulation, as well as validation of its results, were obtained from an in vivo experiment, involving MR imaging of a normal knee while performing isometric leg press against a constant 140 N force. The model was formulated within the framework of a rigid body spring model and solved using forth-order Runge-Kutta, for knee flexion angles between zero and 50 degrees. Results indicated a good agreement between the model predictions for patellar tracking and the experimental results with RMS deviations of about 2 mm for translations (less than 0.7 mm for patellar mediolateral shift), and 4 degrees for rotations (less than 3 degrees for patellar tilt). The contact pattern predicted by the model was also consistent with the results of the experiment and the literature. The joint contact force increased linearly with progressive knee flexion from 80 N to 210 N. The medial retinaculum experienced a peak force of 18 N at full extension that decreased with knee flexion and disappeared entirely at 20 degrees flexion. Analysis of the patellar time response to the quadriceps contraction suggested that the muscle activation most affected the patellar shift and tilt. These results are consistent with the recent observations in the literature concerning the significance of retinaculum and quadriceps in the patellar stability
  6. Keywords:
  7. Anatomical models ; Articular cartilages ; Contact pattern ; Force vectors ; In-vivo experiments ; Joint contact forces ; Knee flexion angle ; Knee flexions ; Mediolateral ; Model prediction ; Model simulation ; MR imaging ; Muscle activation ; Nonlinear springs ; Patellar stability ; Patellar Tendon ; Patellar tilts ; Patellar tracking ; Peak force ; Rigid body ; Rigid body spring models ; Rms deviations ; Runge-Kutta ; Shift-and ; Tensile elements ; Three-dimensional dynamics ; Time response ; Tracking data ; Visco-elastic material ; Activation analysis ; Experiments ; Joints (anatomy) ; Magnetic resonance imaging ; Rigid structures ; Runge Kutta methods ; Three dimensional ; Physiological models ; Aged ; Articular cartilage ; Case report ; Dynamics ; Human ; In vivo study ; Ioint stability ; knee function ; Male ; Muscle isometric contraction ; Nuclear magnetic resonance imaging ; Patella tendon ; Quadriceps femoris muscle ; Rigidity ; Tensile strength ; Translation regulation ; viscoelasticity ; Adult ; Algorithm ; Audiovisual equipment ; Histology ; Physiology ; Pressure ; Time ; Validation study ; Algorithms ; Biomechanics ; Humans ; Models, Anatomic ; Patellofemoral Joint ; Pressure ; Time Factors ; Young Adult
  8. Source: Journal of Biomechanical Engineering ; Volume 134, Issue 4 , 2012 ; 01480731 (ISSN)
  9. URL: http://biomechanical.asmedigitalcollection.asme.org/article.aspx?articleid=1475408