Recon

Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?

A pulsed fluoroscopic investigation

G. Scott, M. A. Imam, A. Eifert, M. A. R. Freeman, V. Pinskerova, R. E. Field, J. Skinner, S. A. Banks

Abstract

Objectives Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back – a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo.

Methods The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m2 (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities.

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Josh Sandberg

Josh Sandberg is the President and CEO of Ortho Spine Partners and sits on several company and industry related Boards. He also is the Creator and Editor of OrthoSpineNews.

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One Comment

  1. “Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?”

    Yes. Kinematic facts are that implant shape drives kinematic restoration. Implant design fact is that one which is tailor-made to match an individual patients native shape and anatomy is most physiologically prone to deliver a better kinematic outcome.

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