CME SECTION

OR

CME on the mini-symposium on biomechanics

1 A moment arm is best defined as:

A A tendency to produce rotation about a pivot when a

force is applied

B The distance a force has to act from a pivot to create

equilibrium

C The generator of torque in a rotating device

D The net effect of all forces acting on a pivot multiplied by

the distance of each from the pivot

E The perpendicular distance of the line of action of a force

from a pivot

2 If an individual’s body weight creates a downward forceof 500N, approximately what joint reaction force isgenerated in the hip on the ipsilateral side if theindividual stands on one leg?

A 50N

B 250N

C 500N

D 1500N

E 5000N

3 Which of the following is the least likely consequence ofincreasing the offset in a new design of femoralcomponent for total hip replacement?

A A tendency to microseparation and edge loading

B Decreased bending moment on the implant

C Decreased generation of force by the abductor muscles

D Increased joint reaction force

E Increased wear rate

4 What is the linear wear threshold for UHMWPE, belowwhich it is thought that osteolysis will not occur as aconsequence of wear debris generation?

A 10 mm

B 50 mm

C 100 mm

D 0.5 mm

E 1 mm

5 Which of the following pairs of steps can be employedto create cross-linked polyethylenes for use in jointreplacement?

A Ethylene oxide treatment and heating

B Heating and Vitamin E incorporation

C High dose electron beam radiation and heating

D Sterilization dose gamma irradiation and heating

E Vitamin E incorporation and high dose gamma radiation

THOPAEDICS AND TRAUMA 27:2 126

6 Approximately what volume of wear occurs in thesecond year after implantation of a second generationmetal-on-metal hip prosthesis?

A 1 mm3

B 5 mm3

C 25 mm3

D 50 mm3

E 150 mm3

7 Which of the following statements concerningceramic femoral head in total hip replacement is nottrue?

A Niobium and Zirconium alloy can be coated onto

ceramic heads to improve the mechanical properties

B Phase change on heating Alumina Oxide heads does not

occur, unlike Zirconia Oxide heads

C Reducing the grain size in Alumina Oxide heads re-

duces the risk of implant fracture by an order of

magnitude

D Wear stripes are thought to result from third body wear

E Zirconia oxide femoral heads should never be

autoclaved

8 Which of the following statements concerningcemented, polished taper stems in hip replacement isnot true when they are compared to roughened stems?

A Distal migration wedges the implant, offloading the

cement mantle

B Radial compressive stresses in the cement mantle are

increased

C Shear stress at the implant cement interface is reduced

D The incidence of initial migration is high

E There is a poorer initial interlock with cement

9 Which of the following is not a perceived advantage ofpartial proximal coating in uncemented femoralstems?

A Better initial fixation as it is easier to accurately ream the

relevant region

B Circumferential coatings form a seal preventing wear

debris from entering the femoral canal beyond the

coating

C Less stress shielding

D Less endosteal lysis

E Load is dissipated rather than transferred to the tip of the

prosthesis

� 2013 Published by Elsevier Ltd.

CME SECTION

10 To which of the following material characteristics of animplant does stress shielding most directly relate?

A Stiffness

B Plasticity

C Toughness

D Ultimate tensile strength

E Yield strength

11 It has been suggested that surface nanograins mayrotate during the sliding of hip prostheses to bringwhich constituent towards the surface?

A Carbon

B Chromium

C Cobalt

D Molybdenum

E Niobium

ORTHOPAEDICS AND TRAUMA 27:2 127

12 Which of the following techniques can be used tocharacterize the chemical nature of materials makingup the biofilm on a retrieved prosthetic femoralhead?

A Atom force microscope

B Small angle X-ray scattering

C Transmission electron microscopy

D Tribometry

E X-ray photoelectron spectroscopy

� 2013 Published by Elsevier Ltd.