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 3981
Topic: 1. General Principles & Basic Science
The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score utilizes routine laboratory tests to stratify the risk of necrotizing fasciitis. Which of the following parameters carries the highest potential point value in this scoring system?
Correct Answer & Explanation
. C-reactive protein (CRP)
Explanation
In the LRINEC score, a C-reactive protein (CRP) level > 150 mg/L contributes 4 points, which is the highest single block of points for any individual parameter in the scoring system.
Question 3982
Topic: Infection, Pharmacology & VTE
In the pathogenesis of fracture-related infections, Staphylococcus aureus utilizes a mechanism to regulate virulence factors and biofilm dispersion based on population density. Which specific system is the primary regulator of this quorum sensing?
Correct Answer & Explanation
. agr (accessory gene regulator) system
Explanation
The accessory gene regulator (agr) system in S. aureus is a quorum-sensing system that controls the expression of numerous virulence factors and is critical for biofilm maturation and dispersion.
Question 3983
Topic: 1. General Principles & Basic Science
A 50-year-old diabetic patient with advanced Charcot neuroarthropathy of the midfoot presents with a new chronic overlying ulcer. MRI is equivocal due to profound architectural distortion. Which advanced imaging modality provides the highest specificity for diagnosing underlying osteomyelitis in this setting?
Correct Answer & Explanation
. Three-phase Technetium-99m bone scan
Explanation
The combined leukocyte/bone marrow scan is highly specific for differentiating osteomyelitis from the sterile inflammation of Charcot arthropathy. Osteomyelitis shows uptake of white blood cells without corresponding marrow uptake, whereas a Charcot flare shows concordant uptake.
Question 3984
Topic: 1. General Principles & Basic Science
Which of the following statements most accurately describes the elution profile of antibiotics from polymethylmethacrylate (PMMA) bone cement beads placed in a fracture-related infection?
Correct Answer & Explanation
. A sustained, linear release of antibiotics over a 6-month period
Explanation
Antibiotic elution from PMMA follows a biphasic pattern characterized by a rapid 'burst' release of the drug in the first 24-72 hours, followed by a precipitous decline to sub-therapeutic levels, often acting as a substrate for biofilm if left in place long-term.
Question 3985
Topic: 1. General Principles & Basic Science
A patient reports changes in vocal quality after undergoing a right-sided anterior cervical approach to C6. Which of the following nerves has most likely been injured?
Correct Answer & Explanation
. Vagus
Explanation
Discussion: Generally, a left sided approach to the anterior cervical region is preferred because of the more constant anatomy of the recurrent laryngeal nerve, which results in changes in vocal quality.
Question 3986
Topic: Infection, Pharmacology & VTE
In the United States, groups at risk for community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) within the pediatric and adolescent populations include
Correct Answer & Explanation
. toddlers in daycare.
Explanation
CA-MRSA is a growing problem in the United States. Groups at risk for CA-MRSA include athletes in contact sports and children in daycare. Tennis players, golfers, and runners are at lowest risk because their sports do not require close contact with teammates or competitors. Outbreaks have been noted in Alaskan native, Native American, and Pacific Islander minority populations.
Question 3987
Topic: 1. General Principles & Basic Science
What is the primary role of superficial zone protein (SZP) in articular cartilage?
Correct Answer & Explanation
. Boundary lubrication
Explanation
Lubricin and SZP share a similar primary structure but may differ in posttranslational modifications with O-linked oligosaccharides. The primary physiologic function of SZP appears to be boundary lubrication. SZP does not influence interleukin-1, collagenase, or TIMP directly because these proteins are associated with articular cartilage turnover.
Question 3988
Topic: 1. General Principles & Basic Science
Which osseous landmark indicates the proximal border of the femoral insertion of the posterior cruciate ligament?
Correct Answer & Explanation
. Medial intercondylar ridge
Explanation
DISCUSSION: The posterior cruciate ligament is composed of the anterolateral and posteromedial bundles. The medial intercondylar ridge marks the proximal border of the femoral insertion. Occasionally, a medial bifurcate ridge will separate the anterolateral and posteromedial bundles, and a clear change in slope occurs between the bundles. Knowledge of these osseous landmarks may aid in anatomic reconstruction of the posterior cruciate ligament. The medial interfemoral and interfascicular ridges are not accepted nomenclature.
Question 3989
Topic: 1. General Principles & Basic Science
Poor outcomes with necrotizing fasciitis have been associated with which of the following factors?
Correct Answer & Explanation
. Delay in time to diagnosis
Explanation
Necrotizing fasciitis is an uncommon soft-tissue infection, characterized by widespread fascial necrosis. It is most commonly a polymicrobial infection, with group A beta-hemolytic streptococci the most common bacteria reported. Treatment includes emergent aggressive debridement of all involved tissues and immediate empiric antibiotics covering aerobic, anaerobic, gram-positive, and gram-negative bacteria. The key to treatment involves timely diagnosis, broad-spectrum antibiotic therapy, and aggressive surgical debridement.
Question 3990
Topic: 1. General Principles & Basic Science
A 17-year-old basketball player has a soft-tissue abscess over the anterior aspect of his left knee. The team physician prescribes amoxicillin and the infection resolves. The next week the patient develops fevers and significantly increased pain at the site of the previous infection. What is the most likely diagnosis? Review Topic
Skin and soft-tissue abscesses should be drained and cultured by the treating physician whenever possible. Antibiotic therapy should be guided by antibiotic sensitivities derived from the cultures to identify cases of CA-MRSA and prevent severe recurrent infections. These infections have been associated with significant morbidity, with up to 70% of players requiring hospitalization. A high index of suspicion in at-risk populations is necessary, and empiric treatment with an antibiotic effective against MRSA should be considered until sensitivity results are available. Tinea corporis is a general term for a cutaneous fungal infection. The lesion appears as a well-demarcated erythematous plaque with a raised border and central hypopigmentation, giving it a ring-like appearance. Primary infection with herpes simplex virus can produce constitutional symptoms with burning, tingling, or stinging at the site. Grouped vesicles with clear fluid 1 mm to 2 mm in size form on an erythematous base and then rupture, leaving moist ulcers or crusted plaques. Amoxicillin is appropriate empiric antibiotic therapy for group AStreptococcus, so a recurrent infection is less likely with this organism.
Question 3991
Topic: 1. General Principles & Basic Science
During a left-sided transforaminal lumbar interbody fusion at the L4-5 level, the surgeon notes a significant amount of bleeding that cannot be controlled while using a pituitary rongeur. What anatomic structure has been injured?
Correct Answer & Explanation
. Common iliac artery
Explanation
The surgeon perforated the anterior longitudinal ligament and injured the common iliac artery. Bingol and associates described injuries to the vascular structures during lumbar disk surgery. The common iliac artery was most commonly affected and constituted 76.9% of injuries.
Question 3992
Topic: Infection, Pharmacology & VTE
What is the most common causative bacteria in septic arthritis in children?
Correct Answer & Explanation
. Staphylococcus aureus
Explanation
The spectrum of causative bacteria and frequency of occurrence of specific pathogens in septic arthritis are similar to those seen in osteomyelitis, with Staphylococcus aureus being the most common. Other common causative organisms include Kingella kingae, Streptococcus pneumoniae, Klebsiella species, Salmonella, Brucella melitensis, and Haemophilus influenzae.
Question 3993
Topic: Physiology & Rehabilitation
A 60-year-old male with pre-existing cervical spondylosis presents after a hyperextension injury. He has marked weakness in his hands and upper extremities with minimal weakness in his lower extremities. Which of the following best describes the typical pattern of sensory and bladder dysfunction expected in this specific incomplete spinal cord injury syndrome?
Correct Answer & Explanation
. Complete loss of all sensory modalities below the lesion with a flaccid bladder
Explanation
This patient has Central Cord Syndrome, the most common incomplete spinal cord injury, classically seen in older patients with cervical spondylosis who sustain a hyperextension injury. It affects the centrally located cervical tracts supplying the upper extremities more than the peripherally located sacral/lumbar tracts supplying the lower extremities. Sensory loss is variable (often patchy), and bowel/bladder dysfunction (such as urinary retention) may be present but is less severe than in complete lesions.
Question 3994
Topic: Surgical Anatomy & Approaches
During a volar approach (Henry approach) for open reduction and internal fixation of a distal radius fracture, the surgeon develops the internervous plane. Which two structures define this primary interval?
Correct Answer & Explanation
. Flexor carpi radialis (FCR) and the radial artery
Explanation
The classic volar (Henry) approach to the distal radius utilizes the interval between the flexor carpi radialis (FCR) tendon (median nerve) and the radial artery. The FCR is retracted medially and the radial artery laterally to expose the deeper structures.
Question 3995
Topic: 1. General Principles & Basic Science
Performance parameters developed by the Centers for Medicare and Medicaid Services and the Centers for Disease Control and Prevention regarding prophylactic antibiotics include
Correct Answer & Explanation
. initiation within 1 hour of incision, use of an appropriate antibiotic, and continuation of antibiotics until all surgical drains are removed.
Explanation
There are over 500,000 surgical site infections each year in the U.S. Patients with a surgical site infection are 60% more likely to spend time in an intensive care unit, and are twice as likely to die during the perioperative period. In 2002, the Centers for Medicare and Medicaid Services and the Centers for Disease Control and Prevention initiated the National Surgical Infection Prevention Project to decrease morbidity and mortality in surgical site infections by promoting the appropriate use of perioperative antibiotics. The three performance parameters they developed are initiation of parenteral antibiotics within 1 hour of surgical incision, selection of an appropriate antibiotic, and discontinuation within 24 hours. The entire dose of antibiotics should be administered prior to tourniquet inflation. For total joint arthroplasty, cefazolin or cefuroxime is the preferred prophylactic antibiotic. Vancomycin or clindamycin is indicated for patients with severe allergies or adverse reactions to beta-lactams. Vancomycin can also be used for prophylaxis in hospitals with a "high" frequency of methicillin-resistant Staphylococcus aureus. There is no evidence that the continuation of antibiotics until surgical drains have been removed provides any additional protection against surgical site infection.
Question 3996
Topic: Surgical Anatomy & Approaches
A patient underwent a right hip arthroscopy, CAM resection, and labral repair while positioned supine on a fracture table with a perineal post. The leg was in traction for 4 hours, and no intrasurgical complications were noted. At the 2-week follow-up appointment, the patient was experiencing numbness and tingling in the perineum on the surgical side and noted pain predominantly while sitting. What is the likely cause of these symptoms?
Correct Answer & Explanation
. Traction injury to the sciatic nerve
Explanation
DISCUSSIONAlthough all of these responses are known complications related to hip arthroscopy, the symptoms of perineal numbness and pain associated with prolonged traction time indicate a compression injury to the pudendal nerve against the perineal post used to provide counter traction. Perineal numbness usually occurs on the surgical side, with pain in the area of the anus to the penis/clitoris. Pain is predominantly experienced while sitting, but is relieved when sitting on a toilet. Pain can be relieved with a diagnostic pudendal nerve block. This injury is not unique to hip arthroscopy; it also is described in the trauma literature. To prevent compression-type injuries, a well-padded post larger than 9 cm in diameter should be positioned against the medial thigh. Traction force should be kept to a minimum and theextremity positioned in slight abduction. Continuous traction time should not exceed 2 hours, with intermittent traction used during prolonged procedures.
Question 3997
Topic: 1. General Principles & Basic Science
Which of the following accurately describes the biosynthetic materials tricalcium phosphate (TCP) and hydroxyapatite?
Correct Answer & Explanation
. Once in the body, TCP is partially converted to hydroxyapatite.
Explanation
TCP is resorbed more rapidly, at a rate of 10 to 20 times faster than hydroxyapatite, partially because its larger pore size makes it a weaker substance. It provides significantly less compressive strength than hydroxyapatite. It does partially convert to hydroxyapatite, thus slowing its resorption rate. The absorbing cell of hydroxyapatite is the foreign body giant cell, not the osteoclast. Optimum pore size appears to be between 150 and 500 µm.
Question 3998
Topic: Surgical Anatomy & Approaches
When utilizing an anterolateral surgical approach to the distal tibia for open reduction and internal fixation of a pilon fracture, the vascularity of the lateral skin flap is predominantly supplied by which angiosome?
Correct Answer & Explanation
. Anterior tibial artery
Explanation
The anterolateral approach to the distal tibia uses the internervous plane between the superficial and deep peroneal nerves and relies on the anterior tibial artery angiosome for flap viability. In staged pilon fracture management, surgical incisions must respect these angiosomes to minimize the risk of wound necrosis.
Question 3999
Topic: Biology, Genetics & Bone Healing
A 6-year-old girl is diagnosed with Klippel-Feil syndrome. Physical examination demonstrates a short neck, low posterior hairline, and severely limited cervical range of motion. Given the known associations of this syndrome, which of the following screening tests is mandatory?
Correct Answer & Explanation
. Pulmonary function tests
Explanation
Klippel-Feil syndrome is characterized by congenital fusion of two or more cervical vertebrae. It is highly associated with other systemic anomalies, most notably renal abnormalities (such as unilateral renal agenesis or horseshoe kidney) in >30% of patients. Therefore, a renal ultrasound is a mandatory screening test. Cardiac and hearing evaluations are also routinely indicated.
Question 4000
Topic: Physiology & Rehabilitation
During an anterior thoracoabdominal approach for a T10-L2 fusion, the surgeon ligates multiple segmental vessels. Postoperatively, the patient is noted to have loss of bilateral lower extremity motor function and pain/temperature sensation, but preservation of proprioception and light touch. This syndrome is most likely caused by ischemia in the territory of which of the following vessels?
Correct Answer & Explanation
. Artery of Adamkiewicz
Explanation
The clinical picture describes Anterior Spinal Artery (ASA) Syndrome: loss of motor function (corticospinal tracts) and pain/temperature sensation (spinothalamic tracts) with preservation of dorsal column function (proprioception, vibration, light touch). The Artery of Adamkiewicz (arteria radicularis magna) is the major supplier to the anterior spinal artery in the lower thoracic and upper lumbar regions. It typically arises on the left side between T8 and L1. Ligation or injury during anterior approaches can lead to ASA syndrome.
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