ABOS Part I Comprehensive Review - Batch 71

Question 1

A 58-year-old male presents with progressive right knee pain and a noticeable 'bow-legged' appearance. Clinical examination confirms a varus deformity. A standing full-length AP radiograph is obtained, revealing the image below. Based on Paley's prin

Accepted Answer

Determine the Mechanical Axis Deviation (MAD); it will pass significantly medial to the center of the knee.

Question 2

A 35-year-old female presents with chronic lateral knee pain and a 'knock-kneed' appearance, consistent with a valgus deformity. A standing full-length AP radiograph reveals a Mechanical Axis Deviation (MAD) of 25mm lateral to the center of the knee.

Accepted Answer

Primarily in the distal femur.

Question 3

A 28-year-old male sustained a tibia shaft fracture that healed with a significant varus malunion. Preoperative planning is initiated using Paley's principles. After drawing the proximal and distal mechanical axis lines of the tibia, they intersect a

Accepted Answer

This is a 'resolved apex CORA,' suggesting a multiapical deformity that requires further analysis using the 'middle line' technique.

Question 4

A 62-year-old female presents with severe medial compartment osteoarthritis and a significant varus deformity of her left knee. Preoperative planning is initiated. The Malalignment Test reveals a MAD of 20mm medial to the center of the knee. Joint or

Accepted Answer

Draw a line from the center of the knee joint distally into the tibia at an angle of 87° relative to the proximal tibial joint line.

Question 5

A 40-year-old patient undergoes preoperative planning for a complex tibial deformity. The planning process, as depicted in the image below, has identified two distinct CORAs (CORA₁ and CORA₂) with magnitudes of 34° and 32° respectively. What is the m

Accepted Answer

The deformity is multiapical, and each CORA represents a true anatomic apex requiring a separate osteotomy or a controlled correction strategy.

Question 6

A 16-year-old female presents with a progressive valgus deformity of her right lower extremity. Initial assessment reveals a significant lateral Mechanical Axis Deviation (MAD). Joint orientation angles are measured: mLDFA = 87°, MPTA = 87°, and JLCA

Accepted Answer

To identify if there is a secondary deformity near the ankle joint.

Question 7

A 70-year-old female presents with severe bilateral knee osteoarthritis, with the right knee exhibiting a significant valgus deformity and the left knee a varus deformity. The image below shows the left lower extremity. For the left knee, the mechani

Accepted Answer

It results in accelerated articular cartilage wear in the medial compartment.

Question 8

A 50-year-old male presents with a post-traumatic malunion of the distal femur, resulting in a complex valgus deformity. Initial mechanical axis planning reveals a 'resolved apex CORA' located in the mid-diaphysis, which appears straight. To accurate

Accepted Answer

To deconstruct the complex deformity into its individual, treatable components by identifying true proximal and distal CORAs.

Question 9

A 22-year-old patient presents with a severe valgus deformity of the right lower extremity, as shown in the clinical image. Preoperative planning is initiated. Which of the following combinations of joint orientation angles would most strongly sugges

Accepted Answer

mLDFA = 87°, MPTA = 75°, LDTA = 89°

Question 10

A 48-year-old patient underwent a high tibial osteotomy for a varus deformity. Six months postoperatively, a standing full-length AP radiograph is obtained to assess the correction. According to Paley's principles, what is the ultimate postoperative

Accepted Answer

The Mechanical Axis Deviation (MAD) should be restored to the normal physiologic range (8-10mm medial to the center of the knee).

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Key Takeaway