How effective are added constraints in improving TKR kinematics?

B. H. van Duren, H. Pandit, D. J. Beard, A. B. Zavatsky, J. A. Gallagher, N. P. Thomas, D. T. Shakespeare, D. W. Murray, H. S. Gill

Research output: Contribution to journalArticle

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Abstract

Newer designs of total knee arthroplasty (TKA), through the use of added degrees of constraint, attempt to provide a "guided motion" to restore more normal and predictable kinematics. Two such design philosophies are the posterior stabilised (PS) using a cam-post and the medial pivot (MP) concepts. Knee kinematics of 12 patients with a PS TKA, 13 subjects with a MP TKA and 10 normal subjects were compared. For kinematic assessment, patients underwent fluoroscopic assessment of the knee during a step-up exercise and deep knee bend. Fluoroscopic images were corrected for distortion and assessed using 3D model fitting to determine relative 3D motion, and a 2D method to measure the patellar tendon angle (PTA) as function of knee flexion. For the PS design the cam-post mechanism engaged between 70 degrees and 100 degrees flexion. Between extension and 50 degrees there was forward motion of the contact points. Beyond 60 degrees both condyles rolled moved posteriorly. The majority of the external rotation of the femur occurred between 50 degrees and 80 degrees . The PTA was lower than normal in extension and higher than normal in flexion. The MP exhibited no anterior movement throughout the rage of motion. The medial condyle moved minimally. The lateral contact point moved posteriorly from extension to flexion. The femur rotated externally throughout the range of flexion analysed. The PTA was similar to normal from extension to mid flexion and then higher than normal beyond to high flexion. The PS design fails to fully restrain paradoxical anterior movement and although the cam engages, it does not contribute significantly to overall rollback. The MP knee does not show significant anterior movement, the medial pivot concept appears to achieve near normal kinematics from extension to 50 degrees of knee flexion. However, the results show that at high flexion this design does not achieve normal knee kinematics.
Original languageEnglish
Pages (from-to)S31-7
JournalJournal of Biomechanics
Volume40
Issue numberSupplement 1
DOIs
Publication statusPublished - 2007

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Biomechanical Phenomena
Knee
Kinematics
Arthroplasty
Tendons
Cams
Patellar Ligament
Knee Replacement Arthroplasties
Point contacts
Femur
Rage
Bone and Bones
Exercise

Cite this

van Duren, B. H., Pandit, H., Beard, D. J., Zavatsky, A. B., Gallagher, J. A., Thomas, N. P., ... Gill, H. S. (2007). How effective are added constraints in improving TKR kinematics? Journal of Biomechanics, 40(Supplement 1), S31-7. https://doi.org/10.1016/j.jbiomech.2007.02.016

How effective are added constraints in improving TKR kinematics? / van Duren, B. H.; Pandit, H.; Beard, D. J.; Zavatsky, A. B.; Gallagher, J. A.; Thomas, N. P.; Shakespeare, D. T.; Murray, D. W.; Gill, H. S.

In: Journal of Biomechanics, Vol. 40, No. Supplement 1, 2007, p. S31-7.

Research output: Contribution to journalArticle

van Duren, BH, Pandit, H, Beard, DJ, Zavatsky, AB, Gallagher, JA, Thomas, NP, Shakespeare, DT, Murray, DW & Gill, HS 2007, 'How effective are added constraints in improving TKR kinematics?', Journal of Biomechanics, vol. 40, no. Supplement 1, pp. S31-7. https://doi.org/10.1016/j.jbiomech.2007.02.016
van Duren BH, Pandit H, Beard DJ, Zavatsky AB, Gallagher JA, Thomas NP et al. How effective are added constraints in improving TKR kinematics? Journal of Biomechanics. 2007;40(Supplement 1):S31-7. https://doi.org/10.1016/j.jbiomech.2007.02.016
van Duren, B. H. ; Pandit, H. ; Beard, D. J. ; Zavatsky, A. B. ; Gallagher, J. A. ; Thomas, N. P. ; Shakespeare, D. T. ; Murray, D. W. ; Gill, H. S. / How effective are added constraints in improving TKR kinematics?. In: Journal of Biomechanics. 2007 ; Vol. 40, No. Supplement 1. pp. S31-7.
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