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Technical Briefs

# A Novel Quantitative Approach for Evaluating Contact Mechanics of Meniscal Replacements

[+] Author and Article Information
E. Linder-Ganz1

Research and Development Center, Active Implants Corporation, Netanya, 42505 Israeleran.ganz@activeimplants.com

J. J. Elsner, A. Danino, A. Shterling

Research and Development Center, Active Implants Corporation, Netanya, 42505 Israel

F. Guilak

Duke University Medical Center, Durham, NC 27710

1

Corresponding author.

J Biomech Eng 132(2), 024501 (Jan 28, 2010) (6 pages) doi:10.1115/1.4000407 History: Received August 05, 2009; Revised September 22, 2009; Posted October 05, 2009; Published January 28, 2010; Online January 28, 2010

## Abstract

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees $(n=3)$. Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures—implant-dislocation and implant-impingement on the ligaments—were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.

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## Figures

Figure 1

(a) Mechanical compression setup with a representative human cadaveric knee ready to be tested, and (b) a representative pressure distribution under an intact natural meniscus divided to nine regions

Figure 2

The synthetic meniscal replacement. The bulk was made of polycarbonate-urethane (Bionate 80A) and reinforced circumferentially with polyethylene-based fibers (Dyneema Purity® ), resulting in a composite structure.

Figure 3

(a) An example of pressure maps developed on the tibialis plateau beneath the natural meniscus, (b) an optimal implant, and (c) an oversized implant

Figure 4

(a) Additional example of pressure maps developed on the tibialis plateau beneath the natural meniscus, (b) an optimal implant, and (c) an oversized implant

Figure 5

(a) An example of pressure maps developed on the tibialis plateau beneath the natural meniscus, (b) an optimal implant, and (c) an undersized implant

## Errata

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