Abstract
Robust preclinical test methods involving tribological simulations are required to investigate and understand the tribological function of osteochondral repair interventions in natural knee tissues. The aim of this study was to investigate the effects of osteochondral allograft implantation on the local tribology (friction, surface damage, wear and deformation) of the tissues in the natural knee joint using a simple geometry, reciprocating pin-on-plate friction simulator. In addition, the study aimed to assess the ability of osteochondral grafts to restore a low surface damage, deformation and wear articulation when compared to the native state. A method was developed to characterise and quantify surface damage wear and deformation of the opposing cartilage-bone pin surface using a non-contacting optical profiler (Alicona Infinite Focus). Porcine 12 mm diameter cartilage-bone pins were reciprocated against bovine cartilage-bone plates that had 6 mm diameter osteochondral allografts, cartilage defects or stainless steel pins (positive controls) inserted centrally. Increased levels of surface damage with changes in geometry were not associated with significant increases in the coefficient of dynamic friction. Significant damage to the opposing cartilage surface was observed in the positive control groups. Cartilage damage, deformation and wear (as measured by change in geometry) in the xenograft (2.4 mm3) and cartilage defect (0.99 mm3) groups were low and not significantly different (p > 0.05) compared to the negative control in either group. The study demonstrated the potential of osteochondral grafts to restore the congruent articular surface and biphasic tribology of the natural joint. An optical method has been developed to characterise cartilage wear, damage and deformation that can be applied to the tribological assessment of osteochondral grafts in a whole natural knee joint simulation model.
Highlights
A wide variety of surgical approaches for the repair of early stage osteochondral defects are currently available.[1]
The overall aim of this study was to investigate the effects of osteochondral graft implantation on the local tribology of the natural knee joint using a simple geometry, reciprocating pin-on-plate animal tissue model
A positive increase in dynamic friction was recorded for Positive control group 1 and Positive control group 2 at time points 60, 120 and 180 min when compared to the paired negative control tests
Summary
A wide variety of surgical approaches for the repair of early stage osteochondral defects are currently available.[1]. The transplantation of osteochondral autografts and allografts into the site of osteochondral defects has been used as a surgical approach for the repair of cartilage and underlying bone defects in the knee since the early 1990s.2. In order for them to be successful, osteochondral grafts must possess adequate mechanical and tribological properties to withstand the complex loading environment within the natural knee, be biomechanically stable and become integrated into the natural tissues over time. The tribological properties of the graft, subsequent repair tissues and the resultant level of joint congruency achieved should not compromise the integrity of the surrounding and opposing cartilage surfaces. Osteochondral grafting aims to repair the underlying supporting bone structure and restore a near frictionless articulating surface; Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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