Preliminary biomechanical cadaver study investigating a new load-sharing knee implant

Mehdi Saeidi; Piaras A Kelly; Christian Netzel; Miriam Scadeng; Pranesh Kumar; Deborah Prendergast; Thomas Neitzert; Maziar Ramezani

doi:10.1186/s40634-021-00379-2

Preliminary biomechanical cadaver study investigating a new load-sharing knee implant

J Exp Orthop. 2021 Aug 14;8(1):61. doi: 10.1186/s40634-021-00379-2.

Authors

Mehdi Saeidi¹, Piaras A Kelly², Christian Netzel³, Miriam Scadeng^{4

5}, Pranesh Kumar⁶, Deborah Prendergast⁴, Thomas Neitzert¹, Maziar Ramezani¹

Affiliations

¹ Department of Mechanical Engineering, Auckland University of Technology, Auckland, New Zealand.
² Department of Engineering Science, University of Auckland, Auckland, New Zealand. pa.kelly@auckland.ac.nz.
³ Centre for Advanced Composite Materials, Department of Mechanical Engineering, University of Auckland, Auckland, New Zealand.
⁴ Department of Anatomy and Medical Imaging, Faculty of Health and Medical Sciences, University of Auckland, Auckland, New Zealand.
⁵ Centre for Functional MRI, Department of Radiology, University of California, San Diego, USA.
⁶ Department of Orthopaedic Surgery, Whanganui Hospital, Whanganui, New Zealand.

Abstract

Purpose: One of the major contributors to the progression of knee osteoarthritis (OA) is the condition of loading in the knee joint. Innovatively designed load-sharing implants may be effective in terms of reducing joint load. The effects of these implants on contact joint mechanics can be evaluated through cadaver experiments. In this work, a case study is carried out with cadaver knee specimens to carry out a preliminary investigation into a novel load-sharing knee implant, in particular to study the surgical procedures required for attachment, and to determine the contact pressures in the joint with and without the implant.

Methods: Contact pressure in the tibiofemoral joint was measured using pressure mapping sensors, with and without the implant, and radiographs were conducted to investigate the influence of the implant on joint space. The implant was designed from a 3D model of the specimen reconstructed by segmenting MR images of the knee, and it was manufactured by CNC machining.

Results: It was observed that attachment of the implant does not affect the geometry of the hard/soft tissues. Radiographs showed that the implant led to an increase in the joint space on the medial side. Contact pressure measurements showed that the implant reduced the load on the medial side by approximately 18% under all tested loading conditions. By increasing the load from 800 to 1600 N, the percentage of load reduction in the lateral side was decreased by 8%. After applying 800, 1200, and 1600 N load it was observed that the peak contact pressures were 3.7, 4.6, and 5.5 MPa, respectively.

Conclusions: This new knee implant shows some promise as a treatment for OA, through its creation of a conducive loading environment in the knee joint, without sacrificing or damaging any of the hard or soft tissues. This device could be as effective as, for example, the Atlas® system, but without some complications seen with other devices; this would need to be validated through similar results being observed in an appropriate in vivo study.

Keywords: Cadaver; Extra-articular; Implant; Knee; Osteoarthritis; Tibiofemoral.