ABOS Part I Comprehensive Review - Batch 3

Question 1

A 32-year-old male sustains a transverse mid-diaphyseal femoral fracture. He is treated with a reamed, statically locked intramedullary nail. Biomechanically, what is the primary advantage of this construct over a rigidly compressed plate for this sp

Accepted Answer

It acts as a load-sharing device, allowing controlled micromotion to stimulate secondary bone healing.

Question 2

A 48-year-old female with a comminuted tibial shaft fracture is undergoing intramedullary nailing. The surgeon opts for a reamed technique. What is the most significant biomechanical consequence of reaming the medullary canal in this scenario?

Accepted Answer

It allows for the insertion of a larger diameter nail, significantly increasing bending and torsional stiffness.

Question 3

A 28-year-old male sustains a spiral mid-shaft humeral fracture. Antegrade intramedullary nailing is performed. To achieve optimal rotational stability in this fracture pattern, which biomechanical feature of the construct is most critical?

Accepted Answer

The presence of multiple, appropriately placed interlocking screws in both the proximal and distal fragments.

Question 4

A 55-year-old patient with a comminuted distal tibia fracture is treated with a supramalleolar intramedullary nail. The surgeon places two proximal and two distal interlocking screws. If the surgeon were to remove one proximal and one distal screw (c

Accepted Answer

A longer working length, allowing for increased controlled micromotion at the fracture site.

Question 5

A 70-year-old female with osteopenia sustains a mid-shaft femoral fracture. An IM nail is inserted, but intraoperative imaging reveals the distal tip of the nail terminates approximately 5 cm proximal to the metaphyseal flare. What is the most signif

Accepted Answer

Stress concentration at the nail tip, predisposing to a periprosthetic fracture.

Question 6

A surgeon is choosing an intramedullary nail for a young, active patient with a tibia fracture. They are considering two options: one made of stainless steel and another of titanium alloy. From a biomechanical perspective, which material property is

Accepted Answer

Young's Modulus.

Question 7

A 60-year-old male with a subtrochanteric femoral fracture is undergoing antegrade IM nailing. The surgeon is carefully selecting the entry portal. What is the primary biomechanical rationale for ensuring the entry portal is appropriately positioned,

Accepted Answer

To minimize eccentric reaming and iatrogenic fracture of the trochanteric region, ensuring optimal nail trajectory.

Question 8

A 35-year-old male presents with a segmental femoral shaft fracture, with a 6 cm intervening fragment. He is treated with a reamed, statically locked IM nail. Biomechanically, what is the most significant challenge posed by this fracture pattern to t

Accepted Answer

Significantly increased bending and torsional forces on the nail due to the unsupported segment.

Question 9

A 40-year-old patient with a transverse mid-diaphyseal tibia fracture is initially treated with a statically locked IM nail. After 8 weeks, there is evidence of delayed union. The surgeon decides to dynamize the nail by removing one of the distal int

Accepted Answer

To allow controlled axial micromotion and compression at the fracture site to stimulate callus formation.

Question 10

During antegrade intramedullary nailing of a tibial shaft fracture, the surgeon encounters difficulty advancing the nail past the mid-diaphysis, with the nail tip impinging on the anterior cortex. What is the most likely biomechanical reason for this

Accepted Answer

The nail has a posterior apex bow, which does not match the natural anterior apex recurvatum of the tibia.

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Key Takeaway