ABOS Part I Comprehensive Review - Batch 57

Question 1

A 32-year-old male presents with chronic knee pain and progressive varus deformity following a distal femoral fracture treated non-operatively 5 years prior. A full-length weight-bearing radiograph reveals a mechanical axis deviation (MAD) of 25mm me

Accepted Answer

The primary deformity is located in the femur, causing a varus malalignment.

Question 2

A 45-year-old male presents with a chronic tibial malunion following a high-energy trauma. Clinical examination reveals a significant valgus deformity of the lower limb. A full-length weight-bearing radiograph is obtained for preoperative planning. T

Accepted Answer

The center of rotation of angulation (CORA).

Question 3

A 58-year-old patient presents with a tibial malunion characterized by a varus angulation and a significant medial translation at the fracture site. Preoperative planning identifies the CORA to be located 3 cm distal to the actual fracture site. The

Accepted Answer

Perform the osteotomy at the fracture site and place the hinge of the external fixator at the CORA.

Question 4

A 28-year-old patient presents with a pure angular valgus deformity of the proximal tibia, with the CORA precisely located at the metaphyseal apex of the deformity. The surgeon plans a corrective osteotomy and fixation with a circular external fixato

Accepted Answer

Perform the osteotomy at the CORA and place the hinge at the CORA.

Question 5

A 62-year-old patient undergoes a corrective osteotomy for a tibial malunion. During the procedure, the surgeon performs the osteotomy at the original fracture site, which is 4 cm distal to the calculated CORA. The external fixator hinge is also inad

Accepted Answer

Rule 3: Osteotomy and Hinge NOT at CORA.

Question 6

A 35-year-old male presents with a complex tibial malunion involving angulation, translation, and significant internal rotational deformity. The surgeon is planning a multiplanar correction using a circular external fixator. Regarding the rotational

Accepted Answer

Rotational osteotomy correction around the mechanical axis of the femur is technically impractical due to significant diaphyseal displacement.

Question 7

A 50-year-old patient presents with a severe, multiplanar tibial malunion, as depicted in the clinical image below. The deformity includes significant angulation, translation, and a rotational component. The surgeon is preparing for a complex deformi

Accepted Answer

High-quality, standing, weight-bearing, full-length anteroposterior (AP) and lateral radiographs of the entire lower extremity.

Question 8

A 40-year-old patient presents with a complex tibial malunion, exhibiting both valgus angulation and anterior translation in the sagittal plane. The surgeon has meticulously identified the AP CORA and the LAT CORA. What is the next critical step in p

Accepted Answer

Calculate the true magnitude and orientation of the oblique deformity.

Question 9

A 25-year-old patient presents with a tibial shaft malunion, as seen in the clinical image below, resulting in a significant foot progression angle during gait. The orthopedic surgeon is assessing the rotational component of the deformity. According

Accepted Answer

Assessing the thigh-foot axis with the patient prone and knees flexed to 90 degrees.

Question 10

A 48-year-old patient with a history of open tibial fracture and subsequent malunion, complicated by poor soft tissue coverage and a history of infection, requires a complex multiplanar deformity correction. Given these specific patient factors, whic

Accepted Answer

Circular external fixation based on the Ilizarov method.

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Key Takeaway