Factors influencing initial cup stability in total hip arthroplasty.

Background: One of the main goals in total hip replacement is to preserve the integrity of the hip kinematics, by well positioning the cup and to make sure its initial stability is congruent and attained. Achieving the latter is not trivial.

Methods: A finite element model of the cup-bone interface simulating a realistic insertion and analysis of different scenarios of cup penetration, insertion, under-reaming and loading is investigated to determine certain measurable factors sensitivity to stress-strain outcome.

Optimisation of the posterior stabilised tibial post for greater femoral rollback after total knee arthroplasty--a finite element analysis.

Femoral rollback after total knee arthroplasty (TKA) is necessary for flexion beyond 90-100 degrees. Femoral rollback in posterior cruciate substituting TKA occurs as a result of the interaction between the femoral cam and tibial post. The geometric design of the cam post mechanism determines the kinematics of rollback.

Inhibition of particulate debris-induced osteolysis by alendronate in a rat model.

A rat model was used to study the efficacy of alendronate therapy in inhibition of particle-induced periprosthetic osteolysis. A prosthesis was simulated by inserting a cylindrical polymethylmethacrylate plug into the distal femur of 24 rats allowing the plug to communicate with the joint space. Intra-articular injections of irregularly-shaped ultra-high molecular weight polyethylene particles of 20-200 pm in diameter were administered at 2-week intervals.

Misoprostol Inhibits Polymethylmethacrylate-Stimulated Lysosomal Degranulation and IL-1 Release from Neutrophils.

Endoprosthetic orthopedic implants may loosen over time. The mechanism of this loosening process remains poorly understood. Wear debris sloughed from bone cement (polymethylmethacrylate, PMMA) and orthopedic implant materials (metal, ultrahigh-molecular-weight polyethylene) may stimulate inflammatory responses in phagocytic cells which populate the bone-implant interface (synovial-like membrane).