Practice Set 154 of 789
This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
When planning a closing wedge osteotomy to correct a varus deformity, on which aspect of the deformity should the hinge point (axis of rotation) be located?
. The convex side
A 30-year-old patient presents with recurvatum of the knee. Sagittal plane radiographic analysis reveals an abnormal posterior proximal tibial angle (PPTA). What is the normal anatomic range for the PPTA in the sagittal plane?
. 77 - 84 degrees
In the frontal plane, the anatomic axis of the femur differs from the mechanical axis. Which of the following best describes the normal relationship between the femoral anatomic axis and the femoral mechanical axis?
. The anatomic axis diverges 5 to 7 degrees valgus relative to the mechanical axis.
A patient has a combined varus and recurvatum deformity of the tibia. According to Paley's principles, how is the true magnitude of this oblique plane deformity mathematically calculated from orthogonal radiographs?
. By using the Pythagorean theorem with the tangents of the projected angles
When utilizing a Taylor Spatial Frame (TSF) for deformity correction, the concept of the 'virtual hinge' is essential. The virtual hinge is mathematically determined by the software based on which specific user-input parameter?
. The location of the reference fragment and the defined deformity parameters (origin and planes)
A patient presents with a pure translation deformity of the tibial diaphysis without any angular deviation. To completely correct this pure translation, an osteotomy should be performed:
. Exactly at the level of the translation deformity.
A patient requires simultaneous angular correction of a valgus deformity and lengthening of the tibia using an external fixator. Where should the hinge (axis of rotation) be placed relative to the CORA to achieve both goals through a single opening wedge?
. On the concave side, distant from the CORA on the bisector line
During a proximal tibial osteotomy for deformity correction, which neurologic structure is at highest risk when placing the fibular osteotomy in the proximal third of the fibula?
. Common peroneal nerve
In determining the CORA for a long bone deformity, the proximal anatomic axis line and the distal anatomic axis line are drawn. The point where these two lines intersect is geometrically defined as the:
. Center of Rotation of Angulation (CORA)
When analyzing a patient with a limb length discrepancy (LLD), how does isolated femoral shortening (without angular deformity) affect the mechanical axis of the limb in a bipedal stance?
. It does not alter the mechanical axis deviation relative to the knee center if the joints are parallel.
A surgeon is planning an osteotomy to correct a diaphyseal deformity. According to Paley's Rule 1 of deformity correction, if the osteotomy and the hinge are both placed exactly at the Center of Rotation of Angulation (CORA), what is the expected geometric result?
. Pure angulation with collinear mechanical axes
A patient requires correction of a distal femoral varus deformity. The surgeon places the hinge axis at the CORA, but due to poor bone stock at the apex, performs the osteotomy 3 cm proximally. According to Paley's Rule 2, what occurs during this correction?
. The bone ends will translate at the osteotomy site, but the mechanical axes will collineate.
An opening wedge osteotomy is planned for a 45-year-old with genu varum. To perform a purely opening wedge correction without causing unintended translation at the osteotomy site, where must the hinge be positioned?
. On the convex side of the deformity at the CORA.
Review the provided image:
During a complex distal femoral osteotomy using a Taylor Spatial Frame (TSF), what is the primary biomechanical advantage of this hexapod system over a traditional unilateral fixator?
. It allows for simultaneous correction of angulation, translation, and rotation via a virtual hinge.
A patient presents with a severe procurvatum deformity of the midshaft tibia. When analyzing the sagittal plane radiograph, where is the apex of the deformity anatomically located?
. Anteriorly
Planning a tibial osteotomy for a uniapical varus deformity. The osteotomy and the hinge are both placed exactly at the Center of Rotation of Angulation (CORA). According to Paley's principles, what is the expected geometric outcome?
. Pure angulation with complete realignment of the mechanical axes
To correct a uniapical varus deformity of the tibia, an osteotomy is performed distal to the CORA, but the rotational hinge is placed exactly at the CORA. What is the expected radiographic result after correction?
. Angulation with translation of the bone ends but realigned mechanical axes
A resident performs an opening wedge high tibial osteotomy. Both the osteotomy and the hinge axis are placed proximal to the actual CORA. According to Paley's rules, what is the consequence of this configuration?
. A translation deformity will be induced, leaving the mechanical axes parallel but not colinear
When planning a uniapical deformity correction using a pure opening wedge osteotomy, where must the hinge axis be located relative to the deformity?
. On the convex cortex at the level of the CORA
A 45-year-old male is undergoing an osteotomy for a midshaft tibial angular deformity. The surgeon meticulously plans the procedure such that both the osteotomy cut and the Axis of Correction of Angulation (ACA) are placed exactly at the Center of Rotation of Angulation (CORA). According to Paley's osteotomy rules, what is the geometric result of this specific configuration?
. Pure angulation resulting in collinear anatomical axes without translation at the osteotomy site.