ABOS Part I Comprehensive Review - Batch 55

Question 1

A 38-year-old male presents with chronic knee pain and a progressive varus deformity of his left lower extremity. A full-length standing radiograph is obtained, as shown below. The mechanical axis is observed to pass significantly medial to the cente

Accepted Answer

Internal tibial torsion can mask the true extent of the varus deformity, making it appear less severe.

Question 2

A 25-year-old patient presents with a complex tibial deformity involving both angulation and rotation. Preoperative planning involves identifying the Center of Rotation of Angulation (CORA). The diagram below illustrates the concept of CORA. Accordin

Accepted Answer

Placing both the osteotomy and the axis of correction precisely at the CORA to correct angulation without translation.

Question 3

A 55-year-old patient undergoes preoperative planning for a high tibial osteotomy to correct a varus deformity. The surgeon obtains a true anteroposterior (AP) view of the knee with the patella pointing straight forward. The Mechanical Medial Proxima

Accepted Answer

The MPTA is abnormally low, indicating a proximal tibial varus deformity, with a normal range of 85-90 degrees.

Question 4

A 12-year-old patient presents with a 'toeing-in' gait. On physical examination, with the patient prone and knees flexed to 90 degrees, the thigh-foot angle (TFA) is measured. The examiner notes that the axis of the foot is internally rotated by 5 de

Accepted Answer

20 degrees of internal tibial torsion.

Question 5

A surgeon is planning a complex lower extremity osteotomy for a patient with significant combined angulation and rotational deformity. While clinical examination provides initial insights into the torsional profile, what is considered the 'gold stand

Accepted Answer

CT version study, measuring angles between the femoral neck, distal femoral condyles, proximal tibial plateau, and distal tibial plafond.

Question 6

A 40-year-old patient requires correction of a combined tibial deformity consisting of 30 degrees of varus (Angular Deformity, A) and 40 degrees of internal rotation (Rotational Deformity, R). Using Dr. Paley's graphic method, as depicted in the imag

Accepted Answer

37 degrees

Question 7

A surgeon is performing a tibial osteotomy for a patient with a varus deformity. During the procedure, the surgeon decides to make the osteotomy cut at a level 3 cm distal to the identified Center of Rotation of Angulation (CORA). According to Paley'

Accepted Answer

The angulation will be corrected, and the bone ends will translate (shift sideways).

Question 8

The ultimate goal of Dr. Paley's single-cut oblique osteotomy method for combined angulation and rotation deformities, as described in the case, is to achieve which of the following?

Accepted Answer

To restore the patient's mechanical axis, optimize joint orientation, and return physiologic limb function to prevent early-onset osteoarthritis.

Question 9

A 60-year-old patient presents with a distal femoral deformity. During preoperative planning, the surgeon measures the Mechanical Lateral Distal Femoral Angle (mLDFA) on a true AP view of the knee with the patella pointing forward. What is the normal

Accepted Answer

85-90 degrees; defines distal femur valgus alignment.

Question 10

The fundamental principle behind Dr. Paley's single-cut oblique osteotomy for combined angulation and rotation deformities is based on the geometric understanding that:

Accepted Answer

Any two deformities (angulation and rotation) can be mathematically resolved into a single, oblique plane of deformity.

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Key Takeaway