1. General Principles & Basic Science MCQs

When preparing polymethylmethacrylate (PMMA) bone cement for fixing a pathological fracture, the surgeon must understand its mechanical limitations. PMMA is strongest under which of the following mechanical forces?

Cortical bone is described as an 'anisotropic' material. Which of the following statements best defines this property in the context of orthopaedic biomechanics?

A researcher is developing a novel polyethylene component for a total knee arthroplasty. They note that under a constant, unchanging compressive load over several years, the material slowly undergoes increasing plastic deformation. This specific time-dependent property is called:

When evaluating the structural integrity of a cortical bone screw, the bending strength of the screw is proportional to which anatomical parameter of the screw?

A surgeon is performing bridge plating on a comminuted midshaft humerus fracture. To decrease the stiffness of the construct and promote callus formation via relative stability, what modification should be made to the screw configuration?

When optimizing a cortical screw to resist failure in osteoporotic bone, which geometric factor most significantly increases its pullout strength?

During preoperative planning, an orthopedic surgeon decides to switch from a 2mm thick plate to a 4mm thick plate of the same material and width. According to the area moment of inertia, the bending stiffness of the new plate increases by a factor of:

In highly osteoporotic bone, locked plating provides superior fixation compared to conventional non-locked plating primarily by resisting which mechanism of failure?

According to Perren's interfragmentary strain theory, what is the maximum strain tolerated by granulation tissue before it ruptures and prevents the progression of secondary bone healing?

To minimize stress shielding around a non-cemented femoral stem, the implant material should ideally have an elastic (Young's) modulus close to that of cortical bone. Among the following orthopedic metals, which has the lowest elastic modulus?

Cortical bone exhibits viscoelastic properties. When loaded at a very high strain rate, such as during a high-velocity trauma, how do the mechanical properties of the bone change compared to a low strain rate?

A surgeon accidentally uses a stainless steel screw through a titanium plate during fracture fixation. This mixed-metal construct places the patient at highest risk for which type of corrosion?

Which of the following statements correctly describes the inherent mechanical properties of polymethylmethacrylate (PMMA) bone cement?

To maximize purchase in metaphyseal bone, a cancellous screw differs from a cortical screw primarily by having which of the following geometric features?

When evaluating the design of intramedullary implants, a slotted (open-section) nail is compared to an unslotted (closed-section) nail of the exact same material and outer dimensions. The unslotted nail possesses significantly greater resistance to which force?

On the stress-strain curve for an orthopedic alloy, the exact point at which the material transitions from elastic (recoverable) deformation to plastic (permanent) deformation is known as the:

Cortical bone exhibits different mechanical properties (e.g., strength, stiffness) depending on the direction of the applied load. This fundamental biomechanical property is termed:

A 62-year-old male is undergoing a total shoulder arthroplasty via the deltopectoral approach. During the initial dissection of the deltopectoral interval, the surgeon identifies the cephalic vein. Which of the following is the most appropriate management strategy for the cephalic vein, and why?

A 48-year-old competitive tennis player presents with recurrent anterior shoulder instability and significant anterior glenoid bone loss, confirmed by a pre-operative CT scan. The surgeon plans a Latarjet procedure via the deltopectoral approach. During the deep dissection, after retracting the conjoined tendon medially, which critical neurovascular structure is most vulnerable to injury if extreme or uncontrolled medial retraction is applied?

A 28-year-old male collegiate football player sustains a displaced surgical neck fracture of the humerus. Open reduction and internal fixation (ORIF) is planned via the deltopectoral approach. During the approach, the surgeon identifies the deltoid and pectoralis major muscles. What is the correct innervation for these two muscles, respectively, highlighting the internervous plane?