8. Foot and Ankle MCQs

A patient presents with a distal tibial valgus deformity. Preoperative planning identifies the center of rotation of angulation (CORA) precisely at the ankle joint line. To avoid joint penetration, the osteotomy is performed 3 cm proximal to the CORA, but the axis of correction of angulation (ACA) is placed exactly at the CORA. According to Paley's principles (Rule 2), what is the expected geometric outcome of this correction?

Accurate identification of a coronal plane distal tibial deformity relies on normative joint orientation angles. In standard weight-bearing radiographs, what is the normal mechanical lateral distal tibial angle (mLDTA)?

When utilizing a circular external fixator for tibiotalar arthrodesis in a patient with severe post-traumatic osteoarthritis and bone loss, what is the optimal position of the fused ankle to ensure efficient gait?

When applying a circular frame for gradual correction of a rigid equinus deformity of the ankle, where must the hinges (axis of rotation) be placed to prevent iatrogenic compression or distraction of the tibiotalar joint surfaces?

A patient presents with ankle pain. Standing radiographs reveal a Mechanical Lateral Distal Tibial Angle (mLDTA) of 78 degrees (normal 86-92 degrees). The joint line is congruous. Which deformity is present, and what is the typical consequence if left untreated?

When evaluating a varus ankle deformity for a supramalleolar osteotomy, what is the normal radiographic range for the mechanical lateral distal tibial angle (mLDTA)?

An anteroposterior standing radiograph of an ankle with a varus deformity reveals a normal mLDTA of 89 degrees but an abnormal tibiotalar joint line convergence angle (JLCA) of 8 degrees. Where is the primary source of the ankle deformity?

In a patient with a rigid anterior cavus foot deformity, the lateral radiograph reveals the primary CORA is located at the cuneiform-metatarsal joint. To achieve correction using a dorsal closing wedge osteotomy at the midfoot, where must the hinge be located?

A 16-year-old patient presents with severe distal tibial varus and a medially translated talus following trauma. A gradual correction using a circular frame is planned. To simultaneously correct the varus angulation and translate the distal tibial segment (and talus) laterally, where should the mechanical hinge be placed?

During the preoperative radiographic evaluation of an ankle deformity, the mechanical Lateral Distal Tibial Angle (mLDTA) is measured. Which of the following mLDTA values is diagnostic of a significant distal tibial varus deformity?

When correcting a severe rigid equinus contracture using a Taylor Spatial Frame, precise hinge placement is critical to avoid iatrogenic joint damage. Where must the virtual or mechanical hinge be located to allow pure rotation without compressing or distracting the articular cartilage?

A severe rigid cavus foot is being treated with a gradual correction using a Taylor Spatial Frame. The apex of the deformity is located in the midfoot. To minimize the high risk of dorsal skin necrosis during the correction, where should the hinge axis be positioned?

A patient presents with a mid-diaphyseal tibial malunion that has healed in 15 degrees of varus. Assuming the patient has normal, flexible foot joints, what compensatory motion will naturally occur at the subtalar joint to maintain a plantigrade foot during the stance phase of gait?

A patient presents with a severe post-traumatic ankle varus deformity. The mechanical axis of the tibia passes significantly medial to the center of the ankle joint. To determine the CORA for a planned supramalleolar osteotomy, the surgeon draws the anatomical mid-diaphyseal axis of the proximal segment. Which reference line is most appropriate to establish the distal segment's mechanical axis?

A circular external fixator is being applied to gradually correct a severe equinus contracture. The surgeon inadvertently places the mechanical hinges 2 cm anterior to the true anatomical center of rotation of the talar dome. As the equinus is corrected gradually, what iatrogenic complication is most likely to occur?

A patient presents with a rigid midfoot cavus deformity. Radiographs locate the CORA at the naviculocuneiform joint. A dorsal closing wedge osteotomy is planned. According to Paley's rules, to avoid stretching or altering the length of the plantar fascia during correction, where must the hinge be positioned?

A well-circumscribed, radiolucent lesion is found in the calcaneus of a 22-year-old patient. Biopsy confirms chondroblastoma. What makes the calcaneus and other tarsal bones unique regarding the anatomical predilection of chondroblastoma?

What specific size of the Semmes-Weinstein monofilament is considered the gold standard for screening protective sensation in the diabetic foot?

The 5.07 Semmes-Weinstein monofilament is designed to buckle when a specific amount of force is applied to the skin. What is the equivalent force exerted by this monofilament?

A 62-year-old male with a 15-year history of poorly controlled diabetes mellitus presents for a routine foot examination. He is unable to feel the 5.07 Semmes-Weinstein monofilament on the plantar aspect of his feet. This finding indicates an increased risk for developing which of the following conditions?