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.
Question 3141
Topic: 1. General Principles & Basic Science
A 45-year-old male undergoes a medial opening wedge high tibial osteotomy (HTO) with the osteotomy distal to the tibial tubercle. Which of the following is the most likely effect on patellar height?
Correct Answer & Explanation
. Decreased patellar height (patella infera)
Explanation
Medial opening wedge HTO performed proximal to the tibial tubercle elevates the joint line relative to the tubercle. This causes a relative decrease in patellar height, leading to patella infera.
Question 3142
Topic: 1. General Principles & Basic Science
During a medial opening-wedge high tibial osteotomy, if the surgeon opens the anterior and posterior cortices symmetrically with a uniform block, what unintended sagittal plane change will occur?
Correct Answer & Explanation
. Increased posterior tibial slope
Explanation
The proximal tibia is triangular in cross-section, being narrower anteriorly. Symmetrical opening of the anterior and posterior cortices will inadvertently increase the posterior tibial slope.
Question 3143
Topic: 1. General Principles & Basic Science
Which of the following values represents the normal physiologic medial proximal tibial angle (MPTA) in the coronal plane?
Correct Answer & Explanation
. 87 degrees
Explanation
The normal medial proximal tibial angle (MPTA) is typically 87 degrees, with an accepted normal range of 85-90 degrees. Angles significantly lower indicate tibia vara.
Question 3144
Topic: 1. General Principles & Basic Science
If an osteotomy and the hinge are both placed off the CORA and off the bisector line, what is the expected result of the correction?
Correct Answer & Explanation
. Induction of a new translation deformity
Explanation
According to Paley's Rule 3, placing both the osteotomy and the hinge axis outside the CORA and its bisector line results in a new, iatrogenic translation deformity upon angular correction.
Question 3145
Topic: 1. General Principles & Basic Science
The Taylor Spatial Frame (TSF) utilizes the principles of a Stewart-Gough platform to correct complex deformities. How many struts are utilized in this system to allow simultaneous correction in all six degrees of freedom?
Correct Answer & Explanation
. 6
Explanation
The TSF relies on a hexapod configuration utilizing exactly six adjustable struts. This structure provides the ability to correct angulation, translation, and rotation simultaneously in all six degrees of freedom.
Question 3146
Topic: 1. General Principles & Basic Science
According to the principles of deformity correction, if the osteotomy and the axis of correction of angulation (ACA) both pass through the center of rotation of angulation (CORA), what is the resultant effect on the bone?
Correct Answer & Explanation
. Pure angulation without translation
Explanation
Paley's Rule 1 states that when the osteotomy and the ACA are both located at the CORA, the deformity corrects with pure angulation and no translation.
Question 3147
Topic: 1. General Principles & Basic Science
A surgeon is planning a corrective osteotomy for a diaphyseal tibial deformity. If the osteotomy is performed at a level separate from the center of rotation of angulation (CORA), but the axis of correction of angulation (ACA) remains at the CORA, which of the following accurately describes the resulting correction?
Correct Answer & Explanation
. Angulation with expected translation at the osteotomy site
Explanation
Paley's Rule 2 dictates that if the ACA is at the CORA but the osteotomy is at a different level, the mechanical axis will realign, but the bone ends will translate at the osteotomy site.
Question 3148
Topic: 1. General Principles & Basic Science
A 45-year-old active male undergoes a medial opening-wedge high tibial osteotomy (HTO) for isolated medial compartment osteoarthritis with a varus deformity. To avoid unintentionally increasing the posterior tibial slope during this procedure, what is the recommended ratio of the anterior gap to the posterior gap?
Correct Answer & Explanation
. The anterior gap should be approximately one-half of the posterior gap.
Explanation
Because of the triangular shape of the proximal tibia, the anterior gap should be approximately half the size of the posterior gap to maintain the native posterior tibial slope during an opening-wedge HTO.
Question 3149
Topic: 1. General Principles & Basic Science
Which of the following best describes the expected effect on patellar height following a medial opening-wedge high tibial osteotomy (HTO) versus a lateral closing-wedge HTO?
Medial opening-wedge HTO typically decreases patellar height (creates patella baja/infera) by distalizing the tibial tubercle relative to the joint line, whereas lateral closing-wedge HTO tends to increase patellar height (patella alta).
Question 3150
Topic: 1. General Principles & Basic Science
When assessing lower extremity malalignment on a standing anteroposterior radiograph, an abnormally widened Joint Line Convergence Angle (JLCA) (>2 degrees) is most indicative of which of the following?
Correct Answer & Explanation
. Intra-articular deformity or ligamentous laxity
Explanation
The JLCA measures the angle between the distal femoral and proximal tibial articular lines. A widening >2 degrees suggests intra-articular deformity, cartilage loss, or collateral ligament laxity contributing to the malalignment.
Question 3151
Topic: 1. General Principles & Basic Science
According to the principles of deformity correction (Paley's Rules), what is the expected outcome if the osteotomy and the axis of correction of angulation (ACA) both pass directly through the center of rotation of angulation (CORA)?
Correct Answer & Explanation
. Full angular correction without translation
Explanation
According to Osteotomy Rule 1, when the osteotomy and the ACA both pass through the CORA, the mechanical axes realign completely without any translational deformity.
Question 3152
Topic: 1. General Principles & Basic Science
A surgeon performs an opening-wedge high tibial osteotomy (HTO) utilizing a single straight anterior incision. If the osteotomy gap is opened equally anteriorly and posteriorly, what unintended sagittal plane deformity will likely occur?
Correct Answer & Explanation
. Increased posterior tibial slope
Explanation
Due to the triangular shape of the proximal tibia, opening the osteotomy equally anteriorly and posteriorly increases the posterior tibial slope. To maintain the native slope, the anterior gap should be approximately half the size of the posterior gap.
Question 3153
Topic: 1. General Principles & Basic Science
Which of the following is a well-documented consequence on patellofemoral mechanics following an opening-wedge high tibial osteotomy performed distal to the tibial tubercle?
Correct Answer & Explanation
. Decreased patellar height (patella baja)
Explanation
Opening-wedge HTO performed distal to the tibial tubercle distalizes the tubercle relative to the joint line. This results in patella baja and can increase patellofemoral contact pressures.
Question 3154
Topic: Biology, Genetics & Bone Healing
In distraction osteogenesis using the Ilizarov method, a latency period is maintained between the osteotomy and the initiation of distraction. What is the primary biological purpose of this latency period?
Correct Answer & Explanation
. To allow the hematoma to organize and mesenchymal stem cells to populate the gap
Explanation
A latency period of 5-7 days allows the initial fracture hematoma to organize and mesenchymal cells to proliferate. This ensures robust callus formation before distraction begins.
Question 3155
Topic: 1. General Principles & Basic Science
In deformity planning, if the axis of correction of angulation (ACA) is placed exactly at the center of rotation of angulation (CORA), but the osteotomy is performed at a different diaphyseal level, what is the mechanical result?
Correct Answer & Explanation
. Angular correction accompanied by translation of the bone ends
Explanation
This describes Paley's Rule 2. Placing the ACA at the CORA but cutting the bone elsewhere perfectly aligns the proximal and distal mechanical axes, but creates a translational step-off at the osteotomy site.
Question 3156
Topic: 1. General Principles & Basic Science
A Taylor Spatial Frame (TSF) is used to correct a complex multiplanar tibial deformity. The TSF utilizes a Stewart-Gough platform mechanism. Which of the following best describes the fundamental capability of this mechanism?
Correct Answer & Explanation
. It allows simultaneous correction of deformities in all six degrees of freedom
Explanation
The Taylor Spatial Frame utilizes a hexapod (Stewart-Gough) platform. Its six adjustable struts allow for the simultaneous gradual correction of all six degrees of freedom (angulation, translation, and rotation in x, y, and z axes).
Question 3157
Topic: 1. General Principles & Basic Science
During a medial closing-wedge distal femoral osteotomy for a valgus deformity, the surgeon notes a significant unintended extension deformity post-correction. What technical error during the placement of the hinge pin most likely caused this?
Correct Answer & Explanation
. The hinge pin was placed orthogonal to the mechanical axis instead of parallel to the joint line
Explanation
In a closing-wedge osteotomy, to prevent unintended changes in the sagittal plane (flexion/extension), the hinge axis must be perfectly parallel to the joint line in the axial plane.
Question 3158
Topic: 1. General Principles & Basic Science
A 52-year-old female presents with medial knee pain and a varus deformity. Which of the following is considered an absolute contraindication for a high tibial osteotomy (HTO)?
Inflammatory arthropathy (like rheumatoid arthritis) is a contraindication for joint-preserving osteotomies because the disease affects all compartments systemically, leading to predictable early failure.
Question 3159
Topic: Infection, Pharmacology & VTE
A 70-year-old male with poorly controlled diabetes presents with a chronic paronychia of his great toe, which has been present for several months. He has significant pain, erythema, and swelling, and plain radiographs show cortical irregularity and periosteal reaction of the distal phalanx. Which of the following is the most appropriate initial imaging study to confirm the suspected diagnosis?
Correct Answer & Explanation
. C. Plain radiographs (X-rays)
Explanation
Correct Answer: CThe patient's history of chronic paronychia, poorly controlled diabetes (a risk factor for osteomyelitis), and the clinical signs of pain, erythema, and swelling, combined with the suspicion of bone involvement, make plain radiographs (X-rays) the most appropriate initial imaging study. X-rays are readily available, inexpensive, and can effectively demonstrate signs of osteomyelitis such as cortical irregularity, periosteal reaction, and bone erosion, especially in chronic infections. The question states that plain radiographs 'show cortical irregularity and periosteal reaction,' indicating that X-rays have already provided diagnostic information and are the correct initial step for suspected osteomyelitis.Incorrect Options:A. Magnetic Resonance Imaging (MRI):MRI is highly sensitive for osteomyelitis and can detect early changes not visible on X-rays. However, it is a more expensive and less accessible study, typically reserved for cases where X-rays are equivocal or when the extent of soft tissue involvement needs to be precisely delineated. It is not theinitialimaging study when osteomyelitis is suspected.B. Computed Tomography (CT) scan:CT scans are excellent for evaluating cortical bone detail and complex fractures but are less sensitive than MRI for early osteomyelitis and expose the patient to higher radiation. It is not the initial imaging study for suspected osteomyelitis.D. Ultrasound:Ultrasound can be useful for identifying and localizing fluid collections (abscesses) in soft tissues but is not the primary imaging modality for diagnosing osteomyelitis, although it can sometimes show periosteosteal fluid or cortical irregularities.E. Bone scintigraphy:Bone scintigraphy (bone scan) is very sensitive for detecting increased bone turnover associated with infection but lacks specificity and anatomical detail. It is often used when osteomyelitis is suspected but X-rays are negative, or to assess multifocal involvement, but it is not the initial imaging study.
Question 3160
Topic: Infection, Pharmacology & VTE
An 82-year-old male presents with acute onset of severe pain, swelling, and erythema in his right dominant hand, primarily affecting the MCP and PIP joints. He has a history of hypertension, renal insufficiency (eGFR 45 mL/min/1.73m2), and takes a thiazide diuretic. He denies any recent trauma or fever. Physical examination reveals warm, exquisitely tender, swollen joints with overlying shiny, erythematous skin. There are also several firm, non-tender subcutaneous nodules on the dorsal aspect of his hand and forearm, which he states have been present for years. Given the high suspicion for an acute gout flare in the setting of chronic tophaceous disease, an arthrocentesis is performed on the most inflamed MCP joint. The synovial fluid analysis is crucial for definitive diagnosis. Which of the following findings, as depicted in the image, is considered the gold standard for confirming the diagnosis of gout?
Correct Answer & Explanation
. C. Identification of negatively birefringent, needle-shaped crystals under polarized light microscopy
Explanation
The definitive diagnostic test for gout is the identification of negatively birefringent, needle-shaped monosodium urate (MSU) crystals under polarized light microscopy in synovial fluid. This finding confirms the presence of MSU crystals, which are pathognomonic for gout.
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