ABOS Part I Comprehensive Review - Batch 59

Question 1

A 38-year-old male presents with chronic knee pain and progressive deformity following a distal femoral shaft fracture treated non-operatively 5 years prior. Full-length weight-bearing radiographs are obtained, as shown below, revealing a significant

Accepted Answer

Accelerated medial compartment osteoarthritis and increased tensile strain on the lateral collateral ligament (LCL).

Question 2

A 55-year-old patient presents with a long-standing tibial deformity. Radiographic analysis is performed, and the image below illustrates different types of CORA locations. Which panel correctly depicts a pure translation deformity, and what is the t

Accepted Answer

Panel (d); The CORA is theoretically located at infinity.

Question 3

A 42-year-old male presents with a chronic left knee varus deformity following a proximal tibial fracture. Full-length weight-bearing radiographs are obtained. The mechanical lateral distal femoral angle (mLDFA) is measured at 87°, and the medial pro

Accepted Answer

Proximal tibia, indicating a varus deformity.

Question 4

A 28-year-old patient presents with a malunited tibial shaft fracture. Orthogonal radiographs (AP and Lateral) are obtained, as shown below. The AP view demonstrates clear angulation with no medial-lateral step-off, while the lateral view shows paral

Accepted Answer

Variant 1 deformity; The CORA is located exactly at the level of the malunion site.

Question 5

A 60-year-old patient presents with a complex femoral malunion. Initial full-length AP and lateral radiographs reveal both angulation and translation components in both views. The CORA on the AP radiograph projects 3 cm proximal to the malunion site,

Accepted Answer

A Variant 2 deformity, where the angulation and translation are 90 degrees apart but rotated into an oblique plane.

Question 6

A 70-year-old female presents with a chronic varus knee deformity. Preoperative planning includes obtaining full-length weight-bearing radiographs. The mechanical axis is drawn from the center of the femoral head to the center of the ankle joint. Thi

Accepted Answer

The Mechanical Axis Deviation (MAD), quantifying the magnitude of the varus deformity and joint loading.

Question 7

A 30-year-old athlete presents with chronic anterior knee pain and instability after a malunited proximal tibial fracture. Radiographic analysis reveals a normal MPTA and mLDFA, but the Posterior Proximal Tibial Angle (PPTA) is measured at 70°. What

Accepted Answer

Increased anterior tibial translation and increased strain on the anterior cruciate ligament (ACL).

Question 8

A 48-year-old patient with a complex tibial malunion is undergoing preoperative planning. The surgeon is meticulously drawing axes on full-length weight-bearing AP and lateral radiographs. According to Paley's advanced planning principles, what is th

Accepted Answer

The center of the intramedullary canal.

Question 9

A 50-year-old patient presents with a long-standing diaphyseal tibial malunion characterized by varus angulation in the coronal plane and anterior translation (procurvatum) in the sagittal plane. Which of the following is a direct biomechanical conse

Accepted Answer

Altered patellofemoral tracking and increased anterior cruciate ligament (ACL) strain.

Question 10

A 35-year-old patient presents with a complex tibial malunion. Preoperative radiographs are obtained, and the image below illustrates the concept of multiplanar deformities. The surgeon identifies that the angulation and translation components of the

Accepted Answer

Obtain specialized oblique radiographs: one perpendicular to the plane of maximum angulation to show pure angulation, and another orthogonal to show pure translation.

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Key Takeaway