A geometric approach to study the contact mechanisms in the patellofemoral joint of normal versus patellofemoral pain syndrome subjects

Abstract

The biomechanics of the patellofemoral (PF) joint is complex in nature, and the aetiology of such manifestations of PF instability as patellofemoral pain syndrome (PFPS) is still unclear. At this point, the particular factors affecting PFPS have not yet been determined. This study has two objectives: (1) The first is to develop an alternative geometric method using a three-dimensional (3D) registration technique and linear mapping to investigate the PF joint contact stress using an indirect measure: the depth of virtual penetration (PD) of the patellar cartilage surface into the femoral cartilage surface. (2) The second is to develop 3D PF joint models using the finite element analysis (FEA) to quantify in vivo cartilage contact stress and to compare the peak contact stress location obtained from the FE models with the location of the maximum PD. Magnetic resonance images of healthy and PFPS subjects at knee flexion angles of 15°, 30° and 45° during isometric loading have been used to develop the geometric models. The results obtained from both approaches demonstrated that the subjects with PFPS show higher PD and contact stresses than the normal subjects. Maximum stress and PD increase with flexion angle, and occur on the lateral side in healthy and on the medial side in PFPS subjects. It has been concluded that the alternative geometric method is reliable in addition to being computationally efficient compared with FEA, and has the potential to assess the mechanics of PFPS with an accuracy similar to the FEA.

Contribution of a distal radioulnar joint stabilizer on forearm stability: A modeling study

“…23–25,27–30 An average element size of 1.5 mm was used for tetrahedral elements, whereas an average element size of 2 mm was used for hexahedral elements as similar to the previous study. 31 The forearm model had 389,581 elements, whereas the stabilizer had 9145 elements. Surface-to-surface contact discretization was applied to the humeroulnar joint, humeroradial joint, proximal radioulnar joint, DRUJ, and radiocarpal joints, where the contact was considered frictionless.…”

“…While finite element (FE) analysis is necessary when quantifying the stress/strain in the structures as well as investigating the interaction between the musculoskeletal models with deformable bodies. 31 Rahman et al 26 developed the elbow FE model for predicting the joint compression and contact area. The strains in the intact and implanted humerus and ulna bones were also simulated via FE analysis.…”

“…Computational models have been increasingly used as a biomechanical tool to quantitatively evaluate joint behavior, instability, and prosthetic replacements of the wrist, elbow, and forearm for various scenarios in advance to clinical and experimental studies. 23–31 The upper extremity models are mainly formulated using rigid body modeling (RBM), and highly efficient for kinematic analysis when the material deformations are not considered. 23–26,30 Spratley and Wayne 24 simulated injury models to create the varus instability of the forearm.…”

Ultrasonographic assessment of quadriceps and patellar tendon thicknesses in patients with patellofemoral pain syndrome

“…Abnormal lower extremity alignment (increased Q angle, genu valgum, tibia varum, structural abnormalities of the patella, etc. ), weakness of the muscles located around the knee and hip joints and excessive physical activity are among the leading causes 2 . These are believed to result in impaired knee extension, increased patellofemoral contact pressure and patellofemoral joint stress, eventually leading to PFPS development.…”

Biphasic Analysis of Cartilage Stresses in the Patellofemoral Joint

“…11,16 Some of these prior computational models have used finite element analyses of the PFJ, where the stress-strain response of the articular layers is described using elastic materials under infinitesimal or finite strains. 10,[17][18][19] However, despite the ability of these models to provide the state of stress within the articular layers, these analyses often focus on reporting contact stresses and kinematics, since these parameters may also be measured experimentally, or stress within the bone.…”