The effect of femoral head size on edge loading in metal‐on‐metal hip joint replacement under dynamic separation conditions

Abstract

Edge loading that occurs in hip joint replacements due to dynamic separation of the joint bearings has been shown to cause severe wear for meal-on-metal bearings. In the present study, the multibody dynamics model for metal-on-metal (MoM) hip joints with a medial-lateral translational mismatch in the centers of rotation of the cup and head has been developed to predict the dynamic separation and contact force of edge loading under gait loading conditions. The effects of larger head diameters (28-55 mm), in combination with the translational mismatch (0-4 mm) and varied cup inclination angles (45 -65 ), on edge loading of MoM bearings have been computationally investigated. For the given translational mismatch, increasing head diameters results in negligible effects on the dynamic separation, contact force and severity of edge loading. Increasing head size also leads to increased offset loading torque which has been found to reach at the level that may cause cup loosening under larger translational mismatch at 4 mm. The result highlights the importance of the cup inclination angle of 45 and a lower translational mismatch to avoid severe edge loading. K E Y W O R D Sedge loading, hip joint replacement, metal-on-metal, multibody dynamics, wear

Segmental Acetabular Defects Managed by Augments in Conjunction with CT During Robotic Total Hip Arthroplasty

“…16°). 13 Cup inclination above 55°(correlating with a CEA < 35°) has been implicated in the development of edge-loading complications with all prosthetic combinations, including ceramic squeaking, metal-on-metal wear, and premature polyethylene wear [14][15][16][17] . In addition, in a native hip, a CEA < 20°i s considered insufficient to contain vertical joint forces, leading to early arthritis 18 .…”

Reinforced Screw Fixation of Severe Osteoporotic Intertrochanteric Femur Evans II Fracture Biomechanics Biomechanical Finite Element Analysis

“…In corresponding model A, part of cancellous bone around the spiral blade of common PFNA screws was set as bone cement components and stored as model B, as shown in Figure 2. The apparent density, elastic modulus, Poisson's ratio and yield stress parameters of model B's bone cement material are shown in Table 1 [22][23][24][25][26][27][28] .…”

“…The unit model of the farthest part of the bone was bound to ensure stability during operation. In model C, the cancellous bone around the proximal end of the enhanced screw was set as the bone cement component, as shown in Figure 2 [23] . All parameters of model C's bone cement materials remain unchanged, as shown in Table 1 for reference.…”