Functional biomechanical performance of a novel anatomically shaped polycarbonate urethane total meniscus replacement

Abstract

PurposeTo evaluate the functional biomechanical performance of a novel anatomically shaped, polycarbonate urethane total meniscus implant.MethodsFive human cadaveric knees were flexed between 0° and 90° under compressive loads mimicking a squat movement. Anteroposterior (AP) laxity tests were performed in 30° and 90° flexion. Meniscal kinematics and knee laxity were quantified using roentgen stereophotogrammetric analysis. Tibial cartilage contact mechanics were determined in 90° flexion. Measurements were repeated for the native medial meniscus, the implant, after total medial meniscectomy and allograft transplantation.ResultsThe implant and allograft displayed increased posterior and medial displacements compared to the native meniscus, yet no differences were found between the implant and allograft. Meniscal condition did not affect rotational laxity. Compared to the native joint, AP laxity for the implant was increased in 30° flexion, but not in 90°. The implant reduced the mean contact pressure compared to meniscectomy but could not restore contact pressures to native meniscus levels. Compared to the native meniscus, the implant significantly increased the peak pressure, while the contact area was reduced. Contact mechanics of the implant and allograft were never statistically different.ConclusionsBiomechanical performance was similar for the implant and allograft. However, both meniscal replacements could not restore outcomes to native meniscus levels or sufficiently improve outcomes after meniscectomy. This was presumably caused by the mobility allowed by the suture-only horn fixation. The similarity of implant and allograft performance suggests that the novel implant has the biomechanical potential to serve as an alternative to meniscal allograft transplantation.

Meniscal Replacement With a Silk Fibroin Scaffold Reduces Contact Stresses in the Human Knee

“…Our formulated hypothesis that partial meniscal replacement using the silk fibroin scaffold will restore tibiofemoral contact mechanics to the intact situation could only partially be confirmed. Similar to previous studies investigating tibial contact mechanics after meniscus replacement, the reduced CA after meniscectomy was not improved . Furthermore, physiological pressure distributions over the whole range of motion comparable to the intact condition were not achieved.…”

“…Previous studies, investigating tibiofemoral contact mechanics after implantation of different materials for meniscal replacement, have also failed to demonstrate a complete restoration of a reduced CA seen after partial or total meniscectomy . Brophy et al tested a porous polyurethane scaffold for partial lateral meniscal replacement in a defect of similar size as in the current study.…”

“…Clinically, it is known that meniscal allograft implantation reduces pain and improves knee joint function during daily activities . Therefore, it can be speculated that it might not be necessary to completely restore knee joint contact mechanics after meniscal replacement in order to provide clinical benefit . The silk fibroin scaffold evaluated in the current study also failed to completely restore physiological peak pressures.…”

Dynamic compression of human and ovine meniscal tissue compared with a potential thermoplastic elastomer hydrogel replacement

“…A number of synthetic materials have been investigated for meniscal replacements . Limitations with previously reported materials include poor durability, mechanics, and biocompatibility . Degradable scaffolds have also been investigated to serve as temporary meniscal replacements but have been shown to have limited mechanical integrity and lead to cartilage damage once tested in vivo .…”

“…[23][24][25][26][27][28][29] Limitations with previously reported materials include poor durability, mechanics, and biocompatibility. [30][31][32] Degradable scaffolds have also been investigated to serve as temporary meniscal replacements but have been shown to have limited mechanical integrity and lead to cartilage damage once tested in vivo. [33][34][35][36][37] Large animal models, such as the ovine model, are often used for in vivo studies of potential meniscal replacements 27,36,38,39 for their similarity to human menisci both with respect to size, 40 single compression mechanical data 6 and structural composition.…”