ABOS Part I Comprehensive Review - Batch 72

Question 1

A 55-year-old male presents with chronic right knee pain and a noticeable bowing of his leg. A full-length standing anteroposterior radiograph is obtained, revealing the following alignment:Based on Paley's principles, what is the primary significanc

Accepted Answer

It serves as the 'alarm bell' indicating the presence of a frontal plane biomechanical problem.

Question 2

A 32-year-old professional athlete is undergoing pre-operative planning for a limb alignment procedure. The surgeon emphasizes the importance of understanding the normal values for joint orientation angles. According to Paley's principles, what are t

Accepted Answer

mLDFA: 87° (defines distal femur); MPTA: 87° (defines proximal tibia).

Question 3

A 60-year-old male presents with progressive medial compartment osteoarthritis and a clinical varus deformity of his right lower extremity. A full-length standing radiograph, similar to the one shown, confirms a positive Mechanical Axis Deviation (MA

Accepted Answer

Medial Proximal Tibial Angle (MPTA)

Question 4

A 30-year-old female presents with chronic lateral knee pain and a noticeable 'knock-knee' appearance. A full-length standing anteroposterior radiograph, similar to the one provided, confirms a negative Mechanical Axis Deviation (MAD) of -15mm. Furth

Accepted Answer

Distal tibia

Question 5

A junior resident, new to limb reconstruction, asks about the fundamental goal of applying Paley's biomechanical principles to deformity correction. Which of the following best encapsulates the primary objective of this systematic approach?

Accepted Answer

To accurately pinpoint the Center of Rotation of Angulation (CORA) and restore ideal limb alignment without iatrogenic problems.

Question 6

A 40-year-old patient presents with a significant Mechanical Axis Deviation (MAD) of +18mm, indicating a varus deformity. Upon detailed radiographic analysis, the Mechanical Lateral Distal Femoral Angle (mLDFA) is measured at 87°. Based on Paley's pr

Accepted Answer

The deformity is primarily located in the tibia.

Question 7

A 28-year-old patient presents with a valgus deformity and a negative Mechanical Axis Deviation (MAD) of -12mm. Radiographic analysis reveals a Medial Proximal Tibial Angle (MPTA) of 87° and a Mechanical Lateral Distal Femoral Angle (mLDFA) of 80°. T

Accepted Answer

The deformity is primarily located in the distal femur.

Question 8

According to the provided case content on Paley's principles, what is identified as the 'first sign of trouble' in the diagnostic journey of limb alignment?

Accepted Answer

An abnormal Mechanical Axis Deviation (MAD).

Question 9

A surgeon is reviewing a full-length standing radiograph of a patient with a perfectly aligned, healthy lower extremity, as depicted in the image. According to Paley's principles, where should the Mechanical Axis of the Lower Extremity ideally pass r

Accepted Answer

Directly through the center of the knee joint, or slightly medial to the tibial spines.

Question 10

A 48-year-old male presents with a long-standing varus deformity of his left knee. Full-length standing radiographs reveal a Mechanical Axis Deviation (MAD) of +15mm. Further measurements show a Mechanical Lateral Distal Femoral Angle (mLDFA) of 87°

Accepted Answer

Identify the Center of Rotation of Angulation (CORA) to plan the osteotomy.

ABOS Part I Orthopaedic Deformity Correction, Limb Reconstruction & Gait Analysis Review | Part 21914

ABOS Part I Orthopedic Board Review: Paley's Principles of Limb Deformity Correction | Part 22024

Key Takeaway