Biomaterials and Tribology for the #FRCS Orth

By Dr Rishi Dhir, FRCS Orth

#frcs #frcslecture #fracs #frcsc #orthopaedics #ortholectures #frcscourses

[youtooyoutoo]

Thank you for this fairly comprehensive review of these critical issues.
re 39:00 The frictional force (resistance to joint movement) is independent of area (on two flat (not round) inflexible surface), only because it is a function of the coefficient of friction times the area, and the coefficient of friction is a function of the normal (perpendicular) force divided by the area of contact.
The micro/macro texture of the proximate surfaces does determine this coefficient of friction, but not the distribution of the force thru the joint. This is important for a couple of reasons;
The force is only perpendicular to a relatively small area of the surfaces of the joint, and fades to zero where the direction of force (roughly a line from the distant foot or hand, & force vectors from any constraining muscles or ligaments) is tangent to that surface, so that is the area that will get the most load & wear.
That (maximal normal) force also varies in magnitude & direction during the cycles of a natural gait or ADLs.
I think I have this right, and it does seem to explain the usually uneven wear patterns in replaced long term artificial joints.

[dhidhigeorge]

Excellent talk sir.!!..Thanks a lot for the great effort.

[PreethamBhat-vg]

MS Preetham Bhat A God's Gifts To Her Parents Mrs Shailaja Bhat and Late Mr U B Bhat and Preethi Bhat, Was Born With Congenital, Muitiple, Deformities, Both Physical and Mental, and Mentally Challenged On January 16th, 1974, At Mission Hosputal Udupi Barely 24 Hours, After Birth She Was Taken To KMC Manipal Hospital For A Thorough Examination BY The Orthopaedic Surgeon, DR Bhaskerandkumar Uncle, and Pediatrician DR Nalini Akka, and I Have Toes Spoear and Between Great Toes and 2nd Toes, and May God Bless You With Lots Of Love Preethi

[mousaedhoussen]

Jin et al report that slight clearance, not complete congruence, is optimal for formation of the optimal fluid film lubrication.