This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 1941
Topic: 6. Spine
When performing the Malalignment Test to assess the lower extremity, the mechanical axis of the lower limb is drawn from the center of the femoral head to the center of the ankle plafond. In a normally aligned limb, where should this line pass relative to the knee joint?
Correct Answer & Explanation
. 8 mm medial to the center of the knee joint
Explanation
In a normally aligned lower limb, the mechanical axis line typically passes slightly medial to the geometric center of the knee, approximately 8-10 mm medial.
Question 1942
Topic: 6. Spine
Despite meticulous surgical synovectomy, the recurrence rate for diffuse TGCT remains high. For patients with symptomatic TGCT associated with severe morbidity or functional limitations, and not amenable to improvement with surgery, a targeted systemic therapy has emerged. Which of the following agents is FDA-approved for this indication, and what is its primary mechanism of action?
Correct Answer: B - Pexidartinib; selective Tyrosine Kinase Inhibitor (TKI) targeting the CSF1 receptorThe case specifically mentions: "Targeted Systemic Therapy (Pexidartinib): A relatively recent breakthrough. Pexidartinib is a selective Tyrosine Kinase Inhibitor (TKI) that targets the CSF1 receptor. By blocking the CSF1 receptor on the recruited macrophages, it effectively starves the tumor of its cellular bulk. It is FDA-approved for adults with symptomatic TGCT associated with severe morbidity or functional limitations, and not amenable to improvement with surgery."A. Methotrexate; inhibits dihydrofolate reductase:Methotrexate is a disease-modifying antirheumatic drug (DMARD) used in inflammatory arthritides like RA, not specifically for PVNS.C. Adalimumab; TNF-alpha inhibitor:Adalimumab is a biologic DMARD used for inflammatory conditions like RA, psoriatic arthritis, and ankylosing spondylitis, not PVNS.D. Rituximab; CD20 monoclonal antibody:Rituximab targets B cells and is used in lymphomas and certain autoimmune diseases, not PVNS.E. Ibuprofen; non-selective COX inhibitor:Ibuprofen is an NSAID, providing symptomatic relief but not addressing the underlying pathology or recurrence of PVNS.
Question 1943
Topic: 6. Spine
A 62-year-old female presents with progressive knee pain and a noticeable bowing of her left lower extremity. A weight-bearing, full-length AP radiograph of the lower extremities is obtained with the patellae facing strictly forward. The Malalignment Test (MAT) is performed, revealing that the mechanical axis passes 15 mm medial to the center of the knee joint. Which of the following is the most appropriate interpretation of this finding?
Correct Answer & Explanation
. The patient has a varus malalignment, severely overloading the medial compartment of the knee.
Explanation
Correct Answer: CThe mechanical axis of the lower extremity (Mikulicz line) should normally pass slightly medial to the center of the knee joint, typically within a zone of 0 to 8 millimeters medial to the tibial spines. When the mechanical axis passes medial to this normal zone (e.g., 15 mm medial), it indicates a varus malalignment. This varus alignment severely overloads the medial compartment of the knee, predisposing the patient to medial compartment osteoarthritis, which aligns with the patient's presentation of progressive knee pain and bowing.Option A is incorrectbecause a valgus malalignment occurs when the mechanical axis passes lateral to the normal zone, overloading the lateral compartment. Passing 15 mm medial is indicative of varus.Option B is incorrectbecause 15 mm medial is outside the normal physiologic range of 0-8 mm medial. It indicates a significant varus malalignment.Option D is incorrectbecause while the patient has a varus malalignment, the MAT alone quantifies the overall deviation (MAD) but does not isolate the anatomical source (femur, tibia, or joint). Further evaluation of joint orientation angles (mLDFA, MPTA, JLCA) is required to determine if the deformity is proximal tibial, distal femoral, or multi-level.Option E is incorrectfor the same reason as D. The MAT identifies the presence and magnitude of MAD but does not isolate the specific bone or joint responsible for the deformity. Further steps in the Paley method are necessary before planning surgical correction.
Question 1944
Topic: 6. Spine
When calculating the Mechanical Axis Deviation (MAD) on a standing long-leg radiograph, the normal mechanical axis of the lower extremity is drawn from the center of the femoral head to the center of the ankle plafond. In a mechanically normal lower limb, where does this line pass in relation to the knee joint?
Correct Answer & Explanation
. Approximately 8 to 10 mm medial to the center of the knee joint.
Explanation
In a mechanically neutral alignment, the mechanical axis passes slightly medial (approximately 8 mm) to the center of the knee joint. This slight medial deviation is a standard parameter used to define normal MAD.
Question 1945
Topic: 6. Spine
A 55-year-old man presents with a medial thrust during gait and knee pain. Full-length standing radiographs are obtained to evaluate Mechanical Axis Deviation (MAD). How is MAD formally defined and quantified on these images?
Correct Answer & Explanation
. The perpendicular distance in millimeters from the center of the knee joint to the mechanical axis line.
Explanation
Mechanical Axis Deviation (MAD) is measured as the perpendicular distance in millimeters from the center of the knee joint to the mechanical axis line (which connects the center of the femoral head to the center of the ankle).
Question 1946
Topic: 6. Spine
A patient is evaluated for lower limb malalignment. The mechanical axis line (center of femoral head to center of ankle mortise) is drawn. In a normal individual, where does this Mechanical Axis Deviation (MAD) line pass relative to the knee joint?
Correct Answer & Explanation
. Slightly medial (approximately 1 to 8 mm) to the center of the knee
Explanation
In a normal extremity, the mechanical axis passes slightly medial to the exact center of the knee joint, typically 1 to 8 mm medial to the midline (usually measured near the medial tibial spine).
Question 1947
Topic: 6. Spine
A surgeon is reviewing a full-length standing radiograph of a patient with a perfectly aligned, healthy lower extremity, as depicted in the image. According to Paley's principles, where should the Mechanical Axis of the Lower Extremity ideally pass relative to the knee joint?
Correct Answer & Explanation
. Directly through the center of the knee joint, or slightly medial to the tibial spines.
Explanation
Correct Answer: BThe text defines the Mechanical Axis of the Lower Extremity and states: 'In a perfectly aligned, healthy limb, this weight-bearing line passes directly through the center of the knee joint, or just slightly medial to the tibial spines (typically 8mm medial to the center of the knee).' This is the ideal alignment for optimal load distribution.Option A is incorrect; passing significantly lateral would indicate a valgus deformity (negative MAD).Option C is incorrect; passing significantly medial would indicate a varus deformity (positive MAD).Option D is incorrect; passing through the lateral compartment suggests a valgus alignment, which is not ideal.Option E is incorrect; the text specifies '8mm medial to the center of the knee,' not lateral, and it's an 'or' condition with 'directly through the center,' not an absolute requirement to be 8mm medial.
Question 1948
Topic: 6. Spine
A 60-year-old patient undergoes a high tibial osteotomy for medial compartment osteoarthritis and varus deformity. Postoperative radiographs, similar to the corrected state shown in the image below, are obtained to assess the outcome. What is considered the ideal target for the mechanical axis deviation (MAD) following a successful realignment osteotomy for medial compartment osteoarthritis?
Correct Answer & Explanation
. The mechanical axis should pass 0-5 mm lateral to the center of the knee.
Explanation
Correct Answer: BFor a high tibial osteotomy (HTO) performed to treat medial compartment osteoarthritis and varus deformity, the ideal target for the mechanical axis deviation (MAD) is to achieve slight valgus alignment. This means the mechanical axis should pass through the central or slightly lateral compartment of the knee, typically 0-5 mm lateral to the center of the knee joint. This slight overcorrection (or 'valgus overcorrection') is intended to offload the diseased medial compartment and transfer weight-bearing forces to the healthier lateral compartment, thereby reducing pain and potentially slowing the progression of osteoarthritis. The image shows the mechanical axis passing through the lateral compartment, indicating successful valgus correction.Option A is incorrect; passing 10-15 mm medial would indicate persistent or worsened varus, which is the opposite of the desired outcome. Option C is incorrect; passing through the medial tibial spine would still significantly load the medial compartment. Option D is incorrect; the MAD is primarily assessed relative to the knee joint, not the ankle joint, for knee osteotomies. Option E is incorrect; the mechanical and anatomical axes are rarely parallel, and their relationship is crucial for understanding deformity, but parallelism is not the goal of realignment.
Question 1949
Topic: Thoracolumbar Spine & Deformity
A 55-year-old patient with significant genu varum and a known 2 cm leg length discrepancy (LLD) in the right leg is undergoing a full-length standing AP radiograph for deformity analysis. To ensure the radiograph captures the true alignment under functional weight-bearing conditions, what specific instruction should be given to the radiologic technologist regarding the LLD?
Correct Answer & Explanation
. Blocks must be placed under the shorter leg to level the pelvis.
Explanation
Correct Answer: CThe text explicitly outlines the protocol for a perfect full-length radiograph: 'If there is a significant leg length discrepancy, blocks must be placed under the shorter leg to level the pelvis, ensuring the radiograph captures the true alignment under functional weight-bearing conditions.'Option A is incorrectbecause standing with equal weight without compensation for LLD would result in pelvic obliquity, distorting the true alignment.Option B is incorrectbecause placing all weight on one leg would not represent functional weight-bearing on both limbs and could introduce further alignment distortions.Option D is incorrectbecause angling the X-ray beam to compensate for pelvic tilt is not the standard method described for LLD. The goal is to level the pelvis physically.Option E is incorrectbecause the fundamental tool for deformity assessment is the 'weight-bearing, full-length anteroposterior (AP) radiograph.' A supine position would eliminate the functional weight-bearing component, which is critical for deformity analysis.
Question 1950
Topic: Thoracolumbar Spine & Deformity
A radiologic technologist is being trained on the proper acquisition of full-length standing AP radiographs for deformity correction. The instructor emphasizes the 'Patella-Forward Rule.' Which of the following best describes the primary reason for strictly adhering to this rule?
Correct Answer & Explanation
. To ensure a true anteroposterior view of the knee joint, preventing rotational distortion of frontal plane angles.
Explanation
Correct Answer: CThe text explicitly states: 'The patella-forward position ensures a true AP view of the knee joint, which serves as the epicenter of lower limb alignment analysis.' It further explains that 'aligning the feet forward can induce significant rotation at the knee. This rotation distorts the frontal plane projection, rendering all subsequent joint orientation angle measurements completely inaccurate.' Therefore, the primary reason is to prevent rotational distortion and ensure accurate frontal plane assessment of the knee.Option A is incorrectbecause patient comfort, while important, is not the primary radiographic principle behind the patella-forward rule.Option B is incorrectbecause while rotation can affect fibula visualization, the primary and most critical impact of the patella-forward rule is on the knee joint's frontal plane projection and angular measurements, not specifically ankle joint visualization.Option D is incorrectbecause while rotation can subtly affect projected limb length, the primary impact of the patella-forward rule is on angular measurements in the frontal plane, not primarily on standardizing leg length measurements, which are more affected by pelvic tilt and overall limb length.Option E is incorrectbecause while a true AP view is generally better for all knee structures, the specific emphasis of the patella-forward rule in deformity correction is on accurate angular measurements for alignment, not primarily on intra-articular pathology like osteophytes or joint space narrowing.
Question 1951
Topic: 6. Spine
When assessing a patient with complex multiplanar deformity, the surgeon orders a CT version study to quantify femoral torsion. The angle of femoral anteversion is classically measured between the axis of the femoral neck and which of the following distal reference lines?
Correct Answer & Explanation
. Posterior femoral condylar axis
Explanation
Femoral version is reliably measured on CT by comparing the axis of the femoral neck proximally to the posterior femoral condylar axis distally. A normal value is typically 15 degrees of anteversion.
Question 1952
Topic: 6. Spine
On a normal standing full-length anteroposterior radiograph of the lower extremity, where should the mechanical axis of the lower limb (Mikulicz line) pass relative to the knee joint?
Correct Answer & Explanation
. Approximately 8 mm medial to the center of the knee
Explanation
The normal mechanical axis of the lower limb passes slightly medial to the exact center of the knee joint, typically about 8 mm medial, distributing slightly more load to the medial compartment.
Question 1953
Topic: 6. Spine
What is the heaviest weight that can be safely applied to the adult cervical spine via Gardner-Wells tong traction?
Correct Answer & Explanation
. Greater than 100 pounds
Explanation
DISCUSSION: Cotler and associates reported on the use of awake skeletal traction to reduce facet fracture-dislocations in 24 patients. Seventeen patients required more than 50 pounds of traction (the “traditional” limit) to achieve reduction. More than 100 pounds of traction was safely used in one-third of the patients in this study. A cadaver study has supported the safe use of traction with weights in excess of 100 pounds. REFERENCES: Cotler JM, Herbison GJ, Nasuti JF, et al: Closed reduction of traumatic cervical spine dislocation using traction weights up to 140 pounds. Spine 1993;18:386-390. Anderson DG, Vaccaro AR, Gavin K: Cervical orthoses and cranioskeletal traction, in Clark CR (ed): The Cervical Spine, ed 4. Philadelphia, PA, Lippincott Williams & Wilkins, 2005, pp 110-121.
Question 1954
Topic: 6. Spine
A 70-year-old man is experiencing neck pain, progressive weakness, and numbness in his arms and legs without bowel or bladder dysfunction or dysphagia. Upon examination, he has atrophy of his upper extremities but normal muscle bulk in his legs. Strength is diffusely 4/5 throughout. Cervical spine radiographs show spondylosis. Electromyography (EMG) reveals fibrillations with increased amplitude in the extensor carpi radialis and pronator teres. Nerve conduction studies demonstrate slowing conduction diffusely in the sural, peroneal, and ulnar nerves, and severe slowing in the median nerve. Testing of the tongue and thoracic paraspinal muscles does not show fibrillations or positive short waves. What is the most likely diagnosis? Review Topic
Correct Answer & Explanation
. Cervical radiculopathy
Explanation
Physical examination and presentation is consistent with possible cervical radiculopathy vs motor neuron disease. EMG findings are most consistent with cervical radiculopathy. There is denervation (fasciculations and positive short waves) of the C6 innervated muscles consistent with radiculopathy. However, evaluation of other body regions does not show evidence of denervation (tongue, thoracic paraspinal muscles). Fasciculations in the hand muscles were not widespread. Nerve conduction suggests the presence of a peripheral polyneuropathy with possible superimposed median neuropathy. Amyotrophic lateral sclerosis is a motor neuron disease that affects both upper and lower neurons. Presentation includes rapid progression of weakness, muscle atrophy, fasciculations, spasticity, dysarthria, dysphagia, and respiratory compromise.
Question 1955
Topic: 6. Spine
Figures 65a and 65b show the MRI scans of a 33-year-old man with severe left leg pain. He has had symptoms for 3 months with progressive worsening pain and function. Examination reveals ankle plantar-flexor weakness and diminished light touch sensation on the plantar surface of the foot. What treatment provides the best outcome? Review Topic
Correct Answer & Explanation
. Laminotomy and limited diskectomy
Explanation
The patient's signs and symptoms are consistent with lumbar radiculopathy. Surgical treatment for this condition has been shown to yield significantly improved outcomes when compared with nonsurgical management. Surgical management is best performed with a laminotomy and removal of the sequestered disk herniation ("limited diskectomy"). A complete (ie, subtotal) diskectomy may reduce the rate of recurrence for disk herniation but has been shown to worsen back pain postoperatively. A laminectomy may be necessary for larger herniations with severe central stenosis; the patient does not meet those criteria and, as noted, a total diskectomy is not indicated. Arthrodesis in the setting of primary lumbar disk herniation is not indicated and is considered overly aggressive treatment.
Question 1956
Topic: 6. Spine
A 75-year-old man presents with worsening low back and bilateral leg pain. The pain worsens with ambulation and improves with sitting. On exam, he has strong DP and PT pulses. Straight leg raise is negative. A MRI of the lumbar spine is performed and is pictured in Figure A. On further questioning, which of the following is the patient also likely to report? Review Topic
Correct Answer & Explanation
. Increased pain walking down stairs
Explanation
The patient has lumbar spinal stenosis with neurogenic claudication and therefore is likely to experience worsening pain with activities that result in lumbar extension, such as walking down stairs.Lumbar spinal stenosis often results from degenerative changes of the intervertebral disc and facet joints which ultimately narrows the space available for the thecal sac and exiting nerve roots. Patients can present with neurogenic claudication, reported as worsening leg and/or back pain with ambulation and diminished walking capacity. MRI may demonstrate disc degeneration/bulging, hypertrophy of the ligamentum flavum and facet capsule, and narrowing of the central canal. Nonoperative management includes NSAIDs, PT and epidural steroid injections (ESI). Surgery is reserved for patients who have failed nonoperative measures and includes decompressive laminectomy with or without fusion depending on presence of instability.Issack et al reviewed degenerative lumbar spinal stenosis. Unlike patients with vascular claudication, patients with neurogenic claudication are able to improve walking tolerance with postural changes, specifically with flexed-forward posture (such as leaning forward on a shopping cart). They are unable to improve their symptoms simply by cessation of walking. Patients with neurogenic claudication tend to lack the trophic changes of the skin on the legs/feet as well as diminished pulses characteristic of vascular disease.Young et al reviewed the utilization of lumbar ESI for low back and leg pain. The authors concluded that lumbar ESI are a reasonable nonsurgical option to provide temporary symptomatic relief. Fluoroscopic guidance facilitates accurate placement of the injection into the epidural space, while its nonuse may lead to higher percentage of technical failures. Lastly, the transforaminal approach is more selectivethan the interlaminar approach and can provide diagnostic information as well as symptom relief.Figures A and B are T1 sagittal and T2 axial MR images, respectively, of the lumbar spine demonstrating significant central canal stenosis most notable at L4-L5 with broad disc protrusion, facet degeneration and infolding of the ligamentum flavum.IncorrectResponses:
Question 1957
Topic: 6. Spine
A 47-year-old man is seen in consultation in the ICU after being admitted and treated emergently for a dissecting aortic aneurysm. Current examination reveals generalized weakness of the lower extremities with a significant decrease in pain and temperature sensation from approximately the waist down. Proprioception is maintained. What is the most likely diagnosis at this time? Review Topic
Correct Answer & Explanation
. Anterior cord syndrome
Explanation
Incomplete cord syndromes include anterior cord syndrome, Brown-Sequard syndrome, central cord syndrome, and posterior cord syndrome. The anterior cord syndrome involves a variable loss of motor function and pain and/or temperature sensation, with preservation of proprioception as seen in this patient. The Brown-Sequard syndrome involves an ipsilateral loss of proprioception and motor function, with contralateral loss of pain and temperature sensation. The posterior cord syndrome is a rare injury and is characterized by preservation of motor function, sense of pain and light touch, with loss of proprioception and temperature sensation below the level of the lesion. The central cord syndrome is characterized with greater motor weakness in the upper extremities than in the lower extremities. The pattern of motor weakness shows greater distal involvement in the affected extremity than proximal muscle weakness. Spinal shock is the period of time, usually 24 hours, after a spinal injury characterized by absent reflexes, flaccidity, and loss of sensation below the level of the injury.
Question 1958
Topic: 6. Spine
Figure 16 shows the radiograph of a 56-year-old man who has neck pain after a rollover accident on his lawnmower. The injury appears to be isolated, and he is neurologically intact. Management of the fracture should consist of:
Correct Answer & Explanation
. Halo vest immobilization.
Explanation
DISCUSSION: The radiograph shows a type IIa Hangman’s fracture, and the classic treatment is halo vest immobilization. Traction should be avoided in type IIa injuries because of the risk of overdistraction. A lesser form of immobilization such as a hard collar or a Minerva jacket can be used for nondisplaced (type I) fractures. Surgery generally is reserved for type III fractures (includes C2-3 facet dislocation), or extenuating circumstances such as multiple trauma or other fractures of the cervical spine that require surgical stabilization. REFERENCES: Levine AM, Edwards CC: The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am 1985;67:217-226. Jackson RS, Banit DM, Rhyne AL III, et al: Upper cervical spine injuries. J Am Acad Orthop Surg 2002;10:271-280.
Question 1959
Topic: 6. Spine
When examining a patient with marked hyperreflexia, which of the following findings best suggests that the condition is not caused by a cervical spine pathology?
Correct Answer & Explanation
. Positive jaw jerk reflex
Explanation
DISCUSSION: A positive jaw jerk reflex suggests that the problem is above the level of the pons. All of the other physical signs are exhibited in patients with cervical myelopathy. Although these signs also may be present in conditions affecting the brain, they do not help differentiate between a brain etiology and a cervical spine etiology. A jaw jerk reflex, however, is not present in patients with cervical myelopathy alone. REFERENCES: Montgomery DM, Brower RS: Cervical spondylotic myelopathy: Clinical syndrome and natural history. Orthop Clin North Am 1992;23:487-493. Ono K, Ebara S, Fuji T, Yonenobu K, Fujiwara K, Yamashita K: Myelopathy hand: New clinical signs of cervical cord damage. J Bone Joint Surg Br 1987;69:215-219. An HS, Simpson JM: Surgery of the Cervical Spine. Baltimore, MD, Williams and Wilkins, 1994.
Question 1960
Topic: 6. Spine
A 32 yr old man with oxalosis is scheduled for a surgical treatment of spinal stenosis. Which of the following organs is most likely to show signs of systemic oxalosis during a preoperative assessment?
Correct Answer & Explanation
. Kidney
Explanation
“Oxalosis is a genetic transmitted, autosomal recessive disorder of glyoxalate metabolism...Nephrolithiasis and nephrocalcinosis, secondary to calcium oxalate hypersaturation in the patient’s kidney, usually cause an initial presentation of renal colic and/or asymptomatic gross hematuria...[and later] chronic renal failure” This finding would be detected on either UA or BUN/Cr labs.
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