The Effects of Cyclic Loading and Motion on the Implant–Cement Interface and Cement Mantle of PEEK and Cobalt–Chromium Femoral Total Knee Arthroplasty Implants: A Preliminary Study

Abstract

This study investigated the fixation of a cemented PEEK femoral TKA component. PEEK and CoCr implants were subjected to a walking gait cycle for 10 million cycles (MC), 100,000 cycles or 0 cycles (unloaded control). A method was developed to assess the fixation at the cement–implant interface, which exposed the implants to a fluorescent penetrant dye solution. The lateral condyles of the implants were then sectioned and viewed under fluorescence to investigate bonding at the cement–implant interface and cracking of the cement mantle. When tested for 100,000 cycles, debonding of the cement–implant interface occurred in both PEEK (61%) and CoCr (13%) implants. When the duration of testing was extended (10 MC), the percentage debonding was further increased for both materials to 88% and 61% for PEEK and CoCr, respectively. The unloaded PEEK specimens were 79% debonded, which suggests that, when PEEK femoral components are cemented, complete bonding may never occur. Analysis of cracks in the cement mantle showed an absence of full-thickness cracks in the unloaded control group. For the 100,000-cycle samples, on average, 1.3 and 0.7 cracks were observed for PEEK and CoCr specimens, respectively. After 10 MC, these increased to 24 for PEEK and 19 for CoCr. This was a preliminary study with a limited number of samples investigated, but shows that, after 10 MC under a walking gait, substantial debonding was visible for both PEEK and CoCr implants at the cement–implant interface and no significant difference in the number of cement cracks was found between the two materials.

Third body damage and wear in arthroplasty bearing materials: A review of laboratory methods

“…PMMA cement particles have been identified within the joint originating either during the initial implantation procedure [36] or following degradation of the cement mantle particularly if the underlying bone begins to resorb and the stress distribution through the implant or fixation changes [95] . PMMA cement is the most commonly used contaminant in third body wear simulation.…”

The influence of lubricant temperature on the wear of total knee replacements

“…A PEEK femoral component would have a modulus closer to bone than cobalt chrome, potentially reducing stress shielding. Stress shielding can contribute to bone resorption and subsequent implant loosening [14][15][16]. Furthermore, the lower weight of a PEEK femoral component would be closer to that of the natural tissue than cobalt chrome and the radiolucency of the PEEK polymer also gives potential for improved imaging of the knee replacement and surrounding tissue in situ [17].…”

“…When carrying out pre-clinical wear simulation, especially of novel bearing materials, it is important to understand how different variables influence wear. In this study, the materials of interest were PEEK-OPTIMA™ polymer-on-UHMWPE for use in an all-polymer TKR [14,15,[18][19][20][21] and conventional materials, cobalt chrome-on-UHMWPE. Previous investigations of PEEK-OPTIMA™ polymer-on-UHMWPE in simple geometry wear simulation have shown lubricant temperature to influence wear.…”

Bond strength of metal-free polyether-ether-ketone knee prostheses compared to metal knee prostheses with bone cement: A preliminary in vitro study

“…In previous studies, Lennert de Ruiter et al investigated the initial strength of the PEEK femoral prosthesis bonded to the bone cement and the changes in the bone cement after gait-simulated fatigue experiments. 24,25 They found that although the fixation strength of the PEEK femoral prosthesis with bone cement was lower than that of the metal prosthesis with bone cement, it is adequate for human needs. 24 However, they only studied the initial bond strength of the femoral prosthesis to the bone cement, and did not investigate whether the bond strength of the femoral prosthesis to the bone cement remained reliable after dynamic loading to simulate prolonged human activity.…”