ABOS Part I Comprehensive Review - Batch 46

Question 1

A 38-year-old male presents with progressive right knee pain and a noticeable bowing deformity of his lower extremity. A full-length, weight-bearing anteroposterior radiograph reveals a mechanical axis that passes 15 mm medial to the center of the kn

Accepted Answer

The patient has a varus deformity primarily originating from the proximal tibia.

Question 2

A surgeon is planning a corrective osteotomy for a patient with a complex angular deformity of the tibia. After drawing the proximal and distal mechanical axes of the deformed bone segment, they intersect at a specific point, as depicted in the diagr

Accepted Answer

The Center of Rotation of Angulation (CORA), dictating the ideal osteotomy and hinge placement.

Question 3

A 25-year-old patient requires a corrective osteotomy for a mid-diaphyseal femoral varus deformity. The surgeon identifies the CORA precisely at the apex of the deformity, which is in a healthy bone segment with good soft tissue coverage. The surgica

Accepted Answer

Pure, perfect angular correction with the proximal and distal mechanical axes becoming perfectly collinear without any shift.

Question 4

A 40-year-old patient presents with a severe proximal tibial varus deformity. The CORA is identified just millimeters below the articular joint line, making it anatomically hostile for direct osteotomy and hinge placement. The surgeon decides to perf

Accepted Answer

Osteotomy Rule 2; perfect angular correction accompanied by an obligatory, predictable translation.

Question 5

A surgeon is presented with a patient requiring correction of a complex multi-planar deformity. During preoperative planning, the surgeon considers performing the osteotomy away from the CORA and also placing the mechanical hinge of the external fixa

Accepted Answer

It creates a new, iatrogenic translational deformity while correcting the angulation.

Question 6

A 12-year-old patient presents with a severe varus deformity of the proximal tibia, with the CORA located just below the knee joint line. The surgeon plans a gradual correction using an external fixator. To avoid violating the joint capsule with hard

Accepted Answer

To position the mechanical hinge precisely at the CORA in space, while keeping the physical ring distal to the joint.

Question 7

A surgeon is performing a gradual deformity correction on a patient using an all-wire Ilizarov frame. The preoperative plan indicates that the correction will follow Paley's Osteotomy Rule 2, meaning an obligatory translation of the bone segments is

Accepted Answer

Counter-opposed olive wires

Question 8

A patient is undergoing a deformity correction using a hybrid external fixator construct, as shown in the image below. The surgeon has planned the correction according to Paley's Osteotomy Rule 2, anticipating an obligatory translation at the osteoto

Accepted Answer

It occurs automatically and passively due to the rigid constraint of the half-pins.

Question 9

A surgeon is performing a gradual deformity correction using distraction osteogenesis. The osteotomy gap is being distracted at a rate of 0.5 millimeters per day, divided into two equal increments. After several weeks, radiographs show premature cons

Accepted Answer

Distracting too slow, leading to premature consolidation.

Question 10

A 55-year-old male presents with a severe varus deformity of the right tibia, causing significant knee pain and gait disturbance. Preoperative planning reveals a CORA located in the proximal metaphysis, approximately 4 cm distal to the knee joint lin

Accepted Answer

Rule 1; osteotomy performed at the CORA, and the mechanical hinge placed precisely at the CORA.

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

ABOS Part I Orthopaedic Surgery Board Review: Deformity Correction, Paley's Principles & Fixation MCQs | Part 21961

Key Takeaway