Failure mechanisms of anterior cruciate ligament prostheses:In vitro wear study

Abstract

Previous retrieval studies analyzing the cause of failure of anterior cruciate ligament (ACL) prostheses identified a wear mechanism. However, the relative importance of yarn on bone compared to yarn on yarn wear has not been clearly understood. Therefore, the objective of this study was to elucidate which type of wear is the dominant cause of clinical failure. A variety of ACL prosthetic structures were exposed to two in vitro tests: one for yarn on yarn and the other for a novel yarn on bone wear test system. The latter included the use of both smooth (uncut) and rough (cut) bone surfaces to simulate the conditions around the condyle and at the exit of the tibial tunnel, respectively. The damaged textile structures were viewed by SEM. The various fiber fracture morphologies were identified and classified for the two types of wear tests; for the smooth and rough bone surfaces; for the braided, knitted, woven, and twisted textile structures; and for the three types of fibers that were included: polyethylene terephthalate, polypropylene, and ultrahigh molecular weight polyethylene. The results confirmed that yarn on bone and yarn on yarn wear phenomena are associated with significantly different failure mechanisms. While the more aggressive rough (or cut) bone causes more rapid and intense fiber damage and faster ACL failure than the smooth (uncut) osseous surface, both abradants cause the same type of abrasive wear phenomenon. Differences in failure mechanisms were identified between the different textile structures and the different fiber types. By interpreting the damaged fiber images from clinically failed and retrieved ACL prostheses, we are now able to confirm that the predominant cause of synthetic ACL failure is yarn on bone abrasion. Improvements in future ACL prosthesis designs will only be possible by eliminating or minimizing the effect of this type of abrasive wear.

Primary ACL reconstruction using the LARS device is associated with a high failure rate at minimum of 6-year follow-up

“…They identified 3 mechanisms of prosthetic ACL failure: (1) inadequate fibre abrasion resistance against osseous surfaces, (2) flexural and rotational fatigue of the fibres, and (3) loss of integrity of the textile structure due to unpredictable tissue infiltration during healing. A further in vitro study of synthetic grafts by Poddevin et al found that the predominant cause of failure was yarn on bone abrasion [32]. It is interesting to note that in the current study, all failures occurred at the femoral tunnel aperture.…”

3D-Braided Poly-ε-Caprolactone-Based Scaffolds for Ligament Tissue Engineering

“…These show suitable mechanical and functional results in the short term after surgery. Long-term clinical outcomes are limited due to mechanical disparity, lower abrasion resistance of synthetic ligaments, and limited integration between the graft and host tissue [ 6 , 7 , 8 ].…”

Evaluation of the Mechanical and Thermal Properties of Blended (HDPE/UHMWPE) Nanocomposites with Graphite Nanosheets (GNS)

“…The major cause of failure for these prostheses is through cellular effects induced by wear debris, a result of polyethylene surface attrition at prosthetic surfaces . This same mechanism leads to problems with ligament and tendon prostheses …”