Effect of cementing technique and cement type on thermal necrosis in hip resurfacing arthroplasty—a numerical study

Abstract

Femoral fractures within resurfacing implants have been associated with bone necrosis, possibly resulting from heat generated by cement polymerization. The amount of heat generated depends on cement mantle volume and type of cement. Using finite element analysis, the effect of cement type and volume on thermal necrosis was analyzed. Based on CT-data of earlier implantations, two different models were created: a thick mantle model, representing a low-viscosity ''cement filling'' technique, and a thin mantle model, representing a high viscosity ''cement packing'' technique. Six cement types were analyzed. The polymerization heat generation and its effect on bone necrosis were predicted. In the thin cement mantle models, no thermal necrosis was predicted. Thick cement mantle models produced thermal necrosis at the cement-bone interface depending on cement type. In the worst case, 6% of the bone at the cement-bone interface became necrotic, covering almost the entire cross-sectional area. The current findings suggest a potential thermal drawback of thick cement mantles, although it is unclear whether thermal bone necrosis significantly affects implant fixation or increases the fracture risk. Furthermore, our study showed distinct differences between the heat generated and resulting thermal damage caused by the various cement types. Keywords: finite element analysis; bone cement; thermal necrosis; hip resurfacing arthroplasty Hip resurfacing arthroplasty is an alternative for total hip arthroplasty (THA), with the proposed benefits of bone stock preservation and increased stability. The most common causes for revision of resurfacing arthroplasty are fracture, loosening, and lysis. 1 Although most fractures occur at the implant rim, 20% occur within the femoral component. 2 These fractures have been associated with bone necrosis, 3 often occurring in the bone-cement interface region. It has been hypothesized that this necrotic layer is caused by heat generated by polymerizing bone cement, inducing thermal damage to the bone. 4 Since polymerization of bone cement is an exothermic reaction, the amount of heat generated is proportional to its volume. As a result, hip resurfacings with larger amounts of cement in the femoral head display more fibrous tissue at the cement-bone interface. 5,6 The size and shape of the cement mantle depends on the cementing technique and the type of cement. [7][8][9] The use of low viscosity cement poured into the femoral component 10 leads to a relatively deep cement penetration into the femoral head, 7-9 and a large total cement volume especially when anchoring holes are used. 8 In contrast, when high viscosity cement is manually applied to the femoral head, a more homogeneous, thinner cement mantle is obtained. 8,11 Another factor affecting the temperature rise is the polymerization properties of the cement. 12,13 A fast polymerizing cement will cause a higher peak temperature that will last for a short time, while slower polymerizing cement will cause a lower peak temperature t...

Tuberosity healing after reverse shoulder arthroplasty for acute proximal humerus fractures: the “black and tan” technique

“…With increased thickness of the cement mantle at the proximal humerus adjacent to the tuberosities, temperatures may reach levels high enough to produce thermal bone necrosis. 17,23 The exothermic effects of polymethyl methacrylate were recently studied in a cadaver model that compared the cortical bone temperatures of a full cementation technique with an impaction grafting technique similar to the black and tan technique used in this study. 31 The temperature observed at the surgical neck adjacent to the location of the tuberosity decreased 23% in the impaction grafting technique, dropping the maximum recorded temperature from 52.4 AE 8.1 C to 40.4 AE 4.8 C, below the 47 C threshold thought to create thermal bone necrosis.…”

Are There Long-term Benefits to Cementing the Metaphyseal Stem in Hip Resurfacing?

“…However, there is a concern that this technique might have long-term detrimental effects related to stress shielding [24,29] or thermal necrosis associated with the increase in overall cement needed for component fixation [15,18,20]. Our study compared survivorship, hip scores, and other radiographic findings between hips resurfaced with a cemented metaphyseal stem and hips resurfaced with a press-fit metaphyseal stem.…”

“…All currently available hip resurfacing prostheses feature a metaphyseal stem, typically left uncemented, which helps to facilitate proper alignment for insertion of the femoral component. Cementing this metaphyseal stem increases the area for fixation between the bone and the prosthesis, but this increases the total amount of bone cement needed for fixation, and several studies suggest that the heat generated from the cementing process could lead to thermal necrosis of the surrounding cancellous bone [15,18,20], which could in turn cause femoral neck fracture or femoral loosening. Additionally, cementing the stem may alter the load transfer between the femoral component and the femoral neck, leading to adverse modifications of the proximal femur [24,29].…”

Influence of the stem fixation scenario on load transfer in a hip resurfacing arthroplasty with a biomimetic stem

“…The modeling method of prescribed temperature decrease used in the current study is limited because the actual maximal temperature varies depending on thermal boundary conditions such as cement and stem initial temperature and total volume of cement (Little et al, 2008;Madrala and Nuño, 2010;. Recent experimental studies showed maximal temperatures of 80 1C (Madrala and Nuño, 2010) to 110 1C (Janssen et al, 2012;Race et al, 2007) for bone cement during curing: the current study's hypothesis of a 80 1C maxima is therefore not an extreme value.…”