ABOS Part I Comprehensive Review - Batch 22

Question 1

A 62-year-old male presents with severe medial compartment knee osteoarthritis and a significant genu varum deformity. During gait analysis, he exhibits a pronounced lateral trunk lean to the affected side. His surgeon notes that this compensatory me

Accepted Answer

C. It shifts the ground reaction vector (GRV) laterally, increasing the workload on the hip abductors of the ipsilateral limb.

Question 2

A 55-year-old female presents with a 6-degree varus malalignment of her right knee, as measured by her mechanical axis deviation (MAD). She reports increasing medial knee pain with ambulation. Based on the Paley principles discussed, what is the most

Accepted Answer

C. Nearly 100% of the dynamic joint loading is shifted entirely to the medial compartment.

Question 3

A 48-year-old male presents with a long-standing, severe genu varum deformity of his left knee. Clinically, he exhibits a pronounced Trendelenburg gait on the left side, despite having normal hip abductor strength on manual muscle testing and no sign

Accepted Answer

C. The compensatory femoral abduction required to place the foot flat shortens the gluteus medius, placing it on the inefficient limb of the Blix length-tension curve.

Question 4

A 70-year-old female with end-stage medial compartment osteoarthritis and a severe varus knee deformity is being evaluated for a high tibial osteotomy. Radiographs show significant medial joint space narrowing and lateral joint gapping. Her Joint Lin

Accepted Answer

C. There is significant joint incongruity, likely due to asymmetric cartilage loss and/or lateral ligamentous laxity.

Question 5

A 30-year-old male presents with a progressive varus deformity of his right lower extremity. A full-length standing radiograph is obtained for deformity analysis. The surgeon measures the angle formed between the mechanical axis of the tibia and the

Accepted Answer

C. The patient has tibia vara, with the deformity located in the proximal tibia.

Question 6

A reconstructive orthopedic surgeon is planning an osteotomy for a patient with a simple, uni-apical angular deformity of the tibia. After meticulous preoperative planning using the Paley method, the surgeon identifies the Center of Rotation of Angul

Accepted Answer

B. Pure angular correction with no translation.

Question 7

A 68-year-old male with symptomatic medial compartment knee osteoarthritis and a varus deformity is observed during gait analysis. The physical therapist notes that the patient consistently walks with a 'toe-out' gait pattern, characterized by excess

Accepted Answer

C. To reduce the adductor moment arm by placing the GRV closer to the center of the knee joint, providing symptomatic relief.

Question 8

A 58-year-old male presents with a long-standing, progressive genu varum deformity. Clinically, he exhibits a noticeable varus thrust during the stance phase of gait. Radiographs confirm severe medial compartment collapse. Which of the following stat

Accepted Answer

C. The lateral soft tissue structures, including the LCL, IT band, and PLC, are subjected to chronic tensile overload, leading to structural attenuation and lateral ligamentous laxity.

Question 9

A 40-year-old patient undergoes a full-length standing radiograph as part of a routine orthopedic evaluation. The mechanical axis of the lower limb is measured and found to pass approximately 8 mm medial to the center of the tibial plateau. Based on

Accepted Answer

C. This represents a normal, physiological mechanical axis deviation (MAD).

Question 10

The ultimate goal of any reconstructive orthopedic procedure for lower extremity deformities, as emphasized by the Paley principles, extends beyond achieving a pristine static postoperative radiograph. Which of the following best encapsulates the ove

Accepted Answer

C. To restore fluid, efficient, and pain-free gait, optimizing kinematics and preserving native joint function.

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Key Takeaway