Pre-heating of components in cemented total hip arthroplasty

Fatigue fractures which originate at stress-concentrating voids located at the implantcement interface are a potential cause of septic loosening of cemented femoral components. Heating of the component to 44degreesC is known to reduce the porosity of the cement-prosthesis interface. The temperature of the cement-bone interface was recorded intral-operatively as 32.3degreesC. A simulated femoral model was devised to study the effect of heating of the component on the implant-cement interface. Heating of the implant and vacuum mixing have a synergistic effect on the porosity of the implant-cement interface, and heating also reverses the gradients of microhardness in the mantle. Heating of the implant also reduces porosity at the interface depending on the temperature. A minimum difference in temperature between the implant and the bone of 3degreesC was required to produce this effect. The optimal difference was 7degreesC, representing a balance between maximal reduction of porosity and an increased risk of thermal injury. Using contemporary cementing techniques, heating the implant to 40degreesC is recommended to produce an optimum effect.