ABOS Part I Comprehensive Review - Batch 45

Question 1

A 55-year-old male presents with progressive right knee pain and a noticeable genu varum deformity. Full-length, standing, weight-bearing anteroposterior radiographs are obtained for preoperative planning. The measurements reveal a Mechanical Lateral

Accepted Answer

B. Proximal tibial varus deformity

Question 2

A 30-year-old patient presents with a post-traumatic femoral valgus deformity requiring corrective osteotomy. Preoperative planning identifies a single Center of Rotation of Angulation (CORA) in the distal femur. The surgeon plans to use a monolatera

Accepted Answer

B. The correction will result in pure angulation without any secondary translation.

Question 3

A 40-year-old patient with a tibial varus deformity has a CORA located in the mid-diaphysis. Due to concerns about bone healing in the diaphyseal region, the surgeon decides to perform the osteotomy in the proximal tibial metaphysis, a more biologica

Accepted Answer

B. Angulation combined with a planned, collinear translation of the bone ends.

Question 4

A surgeon is planning a corrective osteotomy for a femoral deformity. During the procedure, both the osteotomy site and the hinge of the external fixator are inadvertently placed away from the calculated Center of Rotation of Angulation (CORA). Based

Accepted Answer

C. Angulation and a non-collinear, unplanned translation, resulting in a 'zigzag' deformity.

Question 5

A 12-year-old patient presents with a complex, multiplanar deformity of the tibia involving significant angulation, shortening, and rotation due to a malunited fracture. The surgeon needs a fixation system that offers the highest degree of versatilit

Accepted Answer

D. Circular external fixator (e.g., Ilizarov or hexapod system)

Question 6

A surgeon is applying a monolateral external fixator to the tibia for a gradual angular correction. To ensure accurate assessment and correction of potential rotational deformities and to maintain optimal control over each bone segment, what is the c

Accepted Answer

B. Insert pins perpendicular to the anatomical axis of each respective bone segment, holding adjacent joints in neutral.

Question 7

A patient presents with a complex tibial deformity involving both angulation and a significant translational component perpendicular to the planned plane of the monolateral fixator pins. The surgeon aims to correct both deformities simultaneously usi

Accepted Answer

C. By applying two angulators (hinges) perpendicular to the pins, utilizing the principle that two equal and opposite angulations equal one translation.

Question 8

A surgeon is planning to correct a significant rotational deformity of the femur using a monolateral external fixator. The patient's neurovascular status is delicate, necessitating a gradual correction rather than an acute intraoperative maneuver. Ba

Accepted Answer

E. Gradual rotation around the long axis of the fixator causes translation, which must be simultaneously corrected with precise calculations.

Question 9

During a gradual angular correction of a femoral deformity using an external fixator, the surgeon observes that the bone ends at the osteotomy site are distracting apart, putting tension on the surrounding soft tissues. This phenomenon is a predictab

Accepted Answer

C. Meticulously adjust the fixator to simultaneously compress (shorten) the osteotomy site, counteracting the secondary lengthening.

Question 10

A resident is preparing to plan a complex lower extremity deformity correction. They have obtained full-length, standing, weight-bearing radiographs and identified several abnormal joint orientation angles. Before selecting an osteotomy site or choos

Accepted Answer

C. Identify and precisely map the Center of Rotation of Angulation (CORA).

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

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Key Takeaway