Pyrocarbon versus cobalt-chromium in the context of spherical interposition implants: an in vitro study on cultured chondrocytes

Abstract

In the context of shoulder surgical replacement, a new generation of spherical interposition implants has been developed, with the implant being a mobile spacer rubbing against the glenoid cartilage and humeral bone cavity. The aim of the present study was to compare pyrocarbon (PyC) versus cobalt-chromium (CoCr) implants, regarding preservation and regeneration of the surrounding tissues. The effect of the biomaterials on chondrocytes was analysed in vitro. Murine primary chondrocytes were grown on discs made of PyC or CoCr using two culture media to mimic either cartilage-like or bone-like conditions (CLC or BLC). Chondrocytes did grow on PyC and CoCr without alteration in cell viability or manifestation of cytotoxicity. The tissue-like cell membranes grown under BLC were examined for the chondrocyte's ability to mineralise (by alizarin red matrix staining, calcium deposit and alkaline phosphatase activity) and for their mechanical properties (by rheological tests). For the chondrocytes grown under CLC and BLC, extracellular matrix components were analysed by histological staining and immunolabelling. Under CLC, PyC promoted type II collagen expression in chondrocytes, suggesting that they may generate a more cartilage-like matrix than samples grown on both CoCr and plastic control. In BLC, the tissue-like cell membranes grown on PyC were more mineralised and homogenous. The mechanical results corroborated the biological data, since the elastic modulus of the tissue-like cell membranes developed on the PyC surface was higher, indicating more stiffness. Overall, the results suggested that PyC might be a suitable biomaterial for spherical interposition implants.

Pyrocarbon interposition shoulder arthroplasty in young arthritic patients: a prospective observational study

“…The modulus of elasticity of pyrocarbon is close to that of diaphyseal bone and more favorable than that of metal. 14,17,22 However, the spherical pyrocarbon implant, being in contact with the cancellous bone of the GT, could explain the important and progressing bone wear observed on the humeral side.…”

“…29 More recently, pyrocarbon 9,[18][19][20] has been proposed for interposition arthroplasty and has proved to be effective in treating small arthritic joints at the wrist and hand level. 2,15,31,32 The main theoretical advantage of pyrocarbon 17 is that its modulus of elasticity is close to that of diaphyseal bone; pyrocarbon promotes the expression of type II collagen and can generate a cartilaginous matrix. The tissues in contact with the pyrocarbon are mineralized and homogeneous.…”

“…The modulus of elasticity of the tissue developed on the surface of the pyrocarbon is more rigid than that in contact with cobalt-chromium, which confirms the biologic data. 17 An in vitro study showed that pyrocarbon in shoulder HA causes less bone wear in simulation of shoulder function compared with cobaltchromium. 25 The question we sought to answer was, Can pyrocarbon interposition arthroplasty be used in larger joints and be an alternative to conventional prostheses for the young arthritic shoulder?…”

Pyrocarbon Humeral Head in a Shoulder Hemiarthroplasty: Preliminary Results at 3 Years Follow-Up and Review of the Current Literature

“…To overcome the main trigger for revision in HSA-symptomatic glenoid-PyC coated HSA was developed [8,9,16]. This manmade biomaterial has the best combination of blood compatibility and physical and mechanical properties [9].…”

“…If on the one hand, total shoulder arthroplasty (TSA) can have a rate of glenoid loosening up to 50% at 10 years [7]; on the other hand, there is the expected glenoid cartilage erosion and subsequent revision after a shoulder hemiarthroplasty (HSA) [8]. A pyrocarbon (PyC) coated humeral head in HSA was hypothesized to overcome the limitations of HSA as it is a durable implant that generates little or no cartilage wear [6,9,10].…”