ABOS Part I Comprehensive Review - Batch 53

Question 1

A 38-year-old male presents with progressive right knee pain and a varus deformity. Full-length, weight-bearing radiographs reveal a mechanical axis that passes 25mm medial to the center of the knee joint. The Mechanical Lateral Distal Femoral Angle

Accepted Answer

The identified MPTA of 78° confirms a significant proximal tibial varus deformity.

Question 2

A 55-year-old female presents with severe medial compartment osteoarthritis of the left knee secondary to a long-standing varus deformity. Preoperative planning reveals a CORA located 5 cm distal to the knee joint line in the proximal tibia. Due to p

Accepted Answer

Rule Two: Correction will require a combination of angulation and translation, necessitating a complete osteotomy.

Question 3

During a closing wedge osteotomy for a tibial varus deformity, the surgeon meticulously makes two converging cuts with an oscillating saw. After removing the bone wedge, a gentle bending force is applied to close the osteotomy. The surgeon observes t

Accepted Answer

It provides significant intrinsic rotational and translational stability to the osteotomy site.

Question 4

A surgeon is performing a closing wedge osteotomy to correct a distal femoral valgus deformity. During the procedure, despite meticulous preoperative planning, the surgeon notices that as the osteotomy gap is closed, the distal segment of the femur i

Accepted Answer

The proximal and distal cuts of the bony wedge were not made perfectly parallel to each other in the desired plane of correction.

Question 5

A 28-year-old patient requires a complex multiplanar deformity correction of the tibia following a malunion. The surgeon plans to use an Ilizarov external fixator. According to the case, how can the external fixator be optimally utilized as a precisi

Accepted Answer

By positioning the mechanical hinge of the fixator at the planned CORA and then using specialized cutting guides attached to the rings, which are aligned parallel to the joint lines.

Question 6

A 40-year-old male undergoes a closing wedge osteotomy for a severe tibial varus deformity. Preoperative planning indicates that the CORA is located intra-articularly, making a Rule One osteotomy impractical. The surgeon therefore plans to perform th

Accepted Answer

The bone segments will become 'jammed,' making the planned translation physically impossible or extremely difficult, leading to a residual deformity.

Question 7

A 60-year-old patient undergoes a high tibial osteotomy for varus knee deformity. The surgeon plans a 10-degree closing wedge correction. To ensure sub-millimeter accuracy, the surgeon utilizes the parallel pin technique. After drilling two stout Ste

Accepted Answer

The two pins will become perfectly parallel to each other after the wedge is closed.

Question 8

A 42-year-old male with a severe distal femoral recurvatum deformity (PDFA 108°) is scheduled for a closing wedge osteotomy. The CORA is identified at the anterior cortex and physis. The surgeon plans to perform a Rule One osteotomy, preserving the c

Accepted Answer

The osteotomy achieves profound intrinsic stability, potentially allowing stabilization with low-profile hardware like staples.

Question 9

A 30-year-old patient presents with a complex post-traumatic deformity of the distal tibia, requiring a closing wedge osteotomy. Preoperative templating indicates a 15-degree correction. The surgeon is aware of potential intraoperative inaccuracies.

Accepted Answer

Failure to account for the kerf of the oscillating saw blade and the Krackow effect.

Question 10

A 68-year-old patient with a long-standing genu varum deformity is scheduled for a high tibial osteotomy. Preoperative radiographs confirm a significant varus deformity with a Mechanical Lateral Distal Femoral Angle (mLDFA) of 87°, a Medial Proximal

Accepted Answer

The JLCA suggests significant intra-articular deformity or ligamentous laxity contributing to the malalignment.

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Key Takeaway