Biomechanics & Biomaterials MCQs

When comparing the torsional rigidity of a solid intramedullary nail to a hollow nail of the same material, the polar moment of inertia is primarily determined by which dimensional parameter?

The combination of a 316L stainless steel screw with a titanium plate in an orthopedic fracture construct significantly increases the risk of which type of corrosion?

In orthopedic biomechanics, the pullout strength of a standard cortical bone screw is most significantly increased by maximizing which of the following design parameters?

During the biomechanical testing of an articular cartilage explant, a constant strain is applied and maintained over time. The gradual decrease in the force required to maintain this constant strain is biomechanically defined as:

A surgeon revises a nonunion treated previously with a stainless steel plate by placing a new titanium plate over the existing retained stainless steel screws. Which type of corrosion is most likely to rapidly degrade the implant interface?

A surgeon places a 316L stainless steel screw through a titanium alloy plate to fix a fracture. What type of corrosion is most likely to occur at the interface between the two different metals?

When optimizing a cortical screw for fixation in diaphyseal bone, which of the following design modifications will most significantly increase its pullout strength?

A ligament is subjected to a constant, sustained load over a period of time, resulting in a progressive increase in deformation. Which of the following biomechanical properties does this describe?

During the clinical management of a clubfoot, a serial casting technique is utilized. The progressive deformation of the contracted soft tissues under a constant applied load over time demonstrates which of the following viscoelastic properties?

Which of the following material properties best explains why a titanium alloy implant exhibits a lower modulus of elasticity compared to a stainless steel implant, thereby reducing stress shielding in orthopaedic fixation?

A patient with a previously implanted stainless steel plate for a femur fracture undergoes revision surgery. The surgeon inadvertently uses a titanium screw to secure an adjunctive piece of hardware in direct physical contact with the stainless steel plate. Over time, rapid corrosion and eventual failure of the less noble metal occurs.

This process is best described as:

What is the predominant mechanism of corrosion seen at the modular head-neck taper junction (trunnionosis) in modern total hip arthroplasty?

A 65-year-old man presents with an acutely swollen and painful knee. Synovial fluid aspiration yields a yellow fluid with a WBC count of 45,000 cells/uL (predominantly PMNs). Polarized light microscopy reveals weakly positively birefringent rhomboid-shaped crystals. What is the composition of these crystals?

Polymethylmethacrylate (PMMA) bone cement is frequently used in arthroplasty for implant fixation. Which of the following additives is responsible for making PMMA radiopaque on standard plain radiographs?

Among the commonly used solid orthopedic implant metals, which of the following has a modulus of elasticity (Young's modulus) closest to that of cortical bone, thereby theoretically reducing the risk of stress shielding?

Galvanic corrosion is an electrochemical process that can lead to early failure of orthopedic implants when two dissimilar metals are in contact in an electrolyte solution (such as body fluid). Which of the following metal combinations presents the highest theoretical risk for galvanic corrosion?

In biomechanics, the mechanical behavior of a material is plotted on a stress-strain curve. The total area under the stress-strain curve from the origin up to the point of ultimate failure represents which mechanical property?

What is the primary purpose of heating (melting or annealing) highly cross-linked polyethylene (HXLPE) above its melting point after gamma irradiation during manufacturing?