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Pediatric Upper Extremity & Spine MCQs

Practice Set 9 of 33

This practice set contains high-yield board review questions covering key concepts in Pediatric Upper Extremity & Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 161

Topic: Pediatric Upper Extremity & Spine

A teenage female is referred to you for evaluation of curvature in her back that was discovered on routine school screening. She is diagnosed with adolescent idiopathic scoliosis. In which of the following scenarios is a bracing program the most appropriate treatment? Review Topic

. Left upper thoracic curve 16 degrees and right main thoracic curve 18 degress, Risser stage in figure B
. Right thoracolumbar curve 35 degrees, Risser stage in figure C
. Left upper thoracic curve 15 degrees and right main thoracic curve 30 degrees, Risser stage in figure B
. Left upper thoracic curve 26 degrees and right main thoracic curve 51 degrees, Risser stage in figure A
. Left thoracolumbar curve 19 degrees, Risser stage in figure A

Correct Answer & Explanation

. Left upper thoracic curve 16 degrees and right main thoracic curve 18 degress, Risser stage in figure B

Explanation

Bracing is most appropriate for skeletally immature patients with a curve > 20/25 degrees. Thus the patient with a left upper thoracic curve of 15 degrees and right main thoracic curve of 30 degrees in Risser stage 1 of growth meets criteria.The treatment of adolescent idiopathic scoliosis (AIS) depends on the magnitude and location of curve as well skeletal maturity of the patient. For curves less than 20 degrees, observation is appropriate until skeletal maturity, with closer intervals duringtimes of peak growth. Curves between 20-25 and 45 degrees in patients who are Risser stage 0,1 or 2 are best treated with bracing to stop progression. Curves with an apex at T7 or below are typically treated with a Boston brace. Curves over 50 degrees generally warrant a discussion about surgery to prevent progression past maturity.In a landmark study, Weinstein et al. evaluated both a randomized and preference based cohort of bracing versus observation. The trial was stopped early due to efficacy of bracing. The rate of treatment success was 72% after bracing and 48% after observation. Treatment success was strongly correlated to time of brace wear.Schlenzka et al. reviewed indications, treatment, and complications associated with brace treatment of AIS. They state that further evidence is necessary to evaluate the efficacy of bracing in AIS.Figure 1, 2, and 3 are radiographs depicting Risser stage 0, 1, and 4 respectively. Illustration B shows radiographs of all Risser stages. Illustration C is the Lenke classification system for idiopathic scoliosis.Incorrect Answers:

Question 162

Topic: Pediatric Upper Extremity & Spine

In girls with idiopathic scoliosis, peak height velocity (PHV) typically occurs at what point?

. Before Risser 1 and menarche
. After Risser 1 and menarche
. Between Risser 1 and menarche
. After menarche but before Risser 1
. At Risser 2

Correct Answer & Explanation

. Before Risser 1 and menarche

Explanation

DISCUSSION: PHV generally occurs while girls are still Risser 0; menarche typically occurs before Risser 1, which has a wide variation in its timing.  The curve magnitude at the PHV is the best prognostic indicator available.  Most untreated patients with curves greater than 30 degrees at PHV require surgery, while patients with smaller curves at that stage typically do notrequire surgery.REFERENCES: Little DG, Song KM, Katz D, Herring JA: Relationship of peak height velocity to other maturity indicators in idiopathic scoliosis in girls.  J Bone Joint Surg Am2000;82:685-693.Anderson M, Hwang SC, Green WT: Growth of the normal trunk in boys and girls during the second decade of life; related to age, maturity, and ossification of the iliac epiphyses.  J Bone Joint Surg Am 1965;47:1554-1564.

Question 163

Topic: Pediatric Upper Extremity & Spine

A 34-year-old man underwent a transtibial amputation as the result of a work-related injury. The amputation was performed at the inferior level of the tibial tubercle. The residual limb has a soft-tissue envelope composed of gastrocnemius muscle that is used as soft-tissue cushioning for the distal tibia. Despite undergoing several prosthetic fittings, he continues to report pain and instability. Examination reveals that the prosthesis appears to fit well with no apparent pressure points or areas of skin breakdown. He is not willing to have any further surgery. Which of the following modifications will most likely provide relief?

. Add double metal uprights and a leather corset.
. Add a supracondylar suspension to the soft suspension.
. Add supracondylar and suprapatellar suspensions to the socket design.
. Replace the socket insert with a silicone suction socket with locking bolt suspension.
. Replace the prosthetic socket with a negative pressure vacuum system.

Correct Answer & Explanation

. Add double metal uprights and a leather corset.

Explanation

DISCUSSION: While transtibial amputees can be fitted with a prosthesis with a residual limb as short as 5 cm, or with retention of the insertion of the patellar tendon, this patient has an unstable gait because of the limited ability of the prosthetic socket to maintain a snug and stable fit.  While cumbersome and bulky, double metal uprights and a corset is the only predictable method of gaining stability. The other methods attempt to add an element of stability; however, they are unlikely to be successful.REFERENCES: Bowker JH, Goldberg B, Poonekar PD: Transtibial amputation: Surgical procedures and postsurgical management, in Bowker JH, Michael JW (eds): Atlas of Limb Prosthetics.  St Louis, MO, Mosby Year Book, 1992, pp 429-452.Kapp S, Cummings D: Transtibial amputation: Prosthetic management, in Bowker JH, Michael JW (eds): Atlas of Limb Prosthetics.  St Louis, MO, Mosby Year Book, 1992, pp 453-478.

Question 164

Topic: Pediatric Upper Extremity & Spine

What risk factor is most associated with progression of idiopathic scoliosis to a curve requiring surgery? Review Topic

. Curve magnitude of more than 20 degrees at menarche
. Curve magnitude of more than 30 degrees at the peak height velocity
. Curve magnitude of more than 30 degrees at skeletal age 12 years
. Curve magnitude of more than 30 degrees at Risser grade 2
. Curve flexibility of less than 50% at Risser grade 2

Correct Answer & Explanation

. Curve magnitude of more than 20 degrees at menarche

Explanation

The magnitude of the curve at the time of the peak height velocity is the most prognostic sign in relationship to surgery. More than 70% of curves that measure more than 30 degrees at this time are likely to reach surgical range.

Question 165

Topic: Pediatric Upper Extremity & Spine

A 13-year-old girl with adolescent idiopathic scoliosis is otherwise healthy with a normal neurologic examination and she began her menstrual cycle 3 months ago. Standing radiographs show a high left thoracic curve from T1-T6 that measures 29 degrees, a right thoracic curve from T7-L1 that measures 65 degrees, and a left lumbar curve from L1-L5 that measures 31 degrees, correcting to 12, 37, and 10 degrees, respectively, on bending films. Her Risser sign is 1. What is the most appropriate management? Review Topic

. Bracing
. Posterior spinal fusion of only the right thoracic curve
. Posterior spinal fusion from T2-L4
. Vertebral body stapling to halt progression of the curve
. Anterior and posterior spinal fusion

Correct Answer & Explanation

. Posterior spinal fusion of only the right thoracic curve

Explanation

The patient has typical adolescent idiopathic scoliosis with a right thoracic curve. This represents a Lenke-1B curve pattern; therefore, only treatment of the thoracic curve is required. The proximal thoracic and thoracolumbar curves are very flexible. The patient is Risser 1 and has just started her menstrual cycles; therefore, she is at significant risk for further curve progression. Bracing is not appropriate for a curve of this magnitude and will not halt the progression of this curve, nor will vertebral body stapling stop this curve. Vertebral body stapling is sometimes useful in small thoracic curves of less than 35 degrees and skeletally immature patients. Anterior and posterior spinal fusion is not required because the patient has no other risk factors, such as neurofibromatosis nor is she at risk for crankshaft. Anterior fusion is an option, but it is not listed.

Question 166

Topic: Pediatric Upper Extremity & Spine
A 7-year-old girl who sustained a type III posteromedial extension supracondylar fracture underwent a closed reduction at the time of injury. Figure 27a shows the position of the fracture fragments prior to percutaneous medial and lateral pin fixation. Following surgery, healing was uneventful and the patient regained a full painless range of motion. Fifteen months after the injury, she now reports loss of elbow motion and moderate pain with activity. A current AP radiograph is shown in Figure 27b. What is the most likely cause of her symptoms?
. Latent osteomyelitis from the percutaneous pins
. Muscle weakness because of a lack of postinjury rehabilitation
. Tardy ulnar nerve paralysis from injury by the medial pin
. Osteonecrosis of the trochlea, producing joint incongruity
. A new acute process

Correct Answer & Explanation

. Osteonecrosis of the trochlea, producing joint incongruity

Explanation

The patient sustained a very distal supracondylar fracture of the humerus. Fractures in this area can disrupt the blood vessels supplying the lateral ossification center of the trochlea. With disturbance of the blood supply in this area, local osteonecrosis occurs and disrupts the support for the overlying articular surface, producing joint incongruity and localized degenerative arthritis.

Question 167

Topic: Pediatric Upper Extremity & Spine
The transverse diameter of the pedicle is most narrow at which of the following levels?
. T1
. T5
. T9
. T12
. L5

Correct Answer & Explanation

. T5

Explanation

DISCUSSION: Of the levels given, T5 has the most narrow pedicle in anatomic studies. One study in patients with scoliosis did note that T7 on the concave side was more narrow than T5, but T7 is not listed here as a possible answer.

Question 168

Topic: Pediatric Upper Extremity & Spine
Figure 27 shows the radiograph of a 68-year-old woman with a history of rheumatoid arthritis who was injured in a fall. History reveals that she has been asymptomatic since undergoing a left total knee arthroplasty 9 years ago. Management should consist of
. skeletal traction.
. immediate application of a cast brace.
. a retrograde supracondylar nail.
. revision total knee replacement.
. resection arthrodesis.

Correct Answer & Explanation

. a retrograde supracondylar nail.

Explanation

A supracondylar fracture of the femur that occurs after total knee replacement can be treated effectively by a number of methods. For this fracture, the use of a retrograde supracondylar nail has been found to be effective in several series. The treatment of these complex injuries needs to injuries needs to be individualized based on the stability of the implant, the quality of the bone, and the extent of comminution of the fracture.

Question 169

Topic: Pediatric Upper Extremity & Spine
A 7-year-old boy has a swollen and deformed right arm after falling off his bicycle. Radiographs reveal a completely displaced posterolateral supracondylar humeral fracture. Examination reveals a warm, pink hand and forearm but absent pulses. What is the next most appropriate step in management?
. Angiography
. Immediate closed reduction and casting in extension
. Surgical exploration and repair of the artery, followed by skeletal stabilization
. Closed reduction and pinning, followed by reassessment of the vascular status
. Magnetic resonance angiography (MRA)

Correct Answer & Explanation

. Closed reduction and pinning, followed by reassessment of the vascular status

Explanation

The incidence of vascular injury in supracondylar humeral fractures is directly related to the degree and direction of displacement. The brachial artery is always injured at the level of the fracture; therefore, angiography or MRA will not assist in locating the injury. The treatment of choice is surgical reduction and stabilization of the fracture, followed by reassessment of the vascular status. If the hand is pink and warm or pulses can be detected with doppler, it is reasonable to follow the extremity closely after surgery. If the arm becomes pulseless and white, immediate anterior exploration of the arm is indicated.

Question 170

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy sustained an elbow injury. Examination in the emergency department reveals that he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. The radial pulse is palpable at the wrist, and sensation is normal throughout the hand. Radiographs are shown. In addition to reduction and pinning of the fracture, initial treatment should include:
. repair of the posterior interosseous nerve.
. repair of the median nerve at the elbow.
. neurolysis of the anterior interosseous nerve.
. observation of the nerve palsy.
. immediate electromyography and nerve conduction velocity studies.

Correct Answer & Explanation

. observation of the nerve palsy.

Explanation

Discussion: The findings are consistent with a neurapraxia of the anterior interosseous branch of the median nerve. This is the most common nerve palsy seen with supracondylar humerus fractures, followed closely by radial nerve palsy. Nearly all cases of neurapraxia following supracondylar humerus fractures resolve spontaneously, and therefore, further diagnostic studies and surgery are not indicated.

Question 171

Topic: Pediatric Upper Extremity & Spine
A 10-year-old girl sustained a Gartland type III supracondylar fracture after falling off a trampoline 1 hour ago. She has a well-perfused hand but no palpable pulses. The remainder of her examination is otherwise normal. What is the next step in treatment?
. Oblique radiographs
. Arteriogram
. Exploration of the brachial artery at the elbow
. Closed reduction and pinning of the elbow
. Open reduction and internal fixation of the elbow

Correct Answer & Explanation

. Closed reduction and pinning of the elbow

Explanation

Most supracondylar fractures are extension type and a Gartland type III is defined as a fracture that is completely displaced (i.e., no posterior cortical hinge). Treatment consists of closed reduction and pinning. If there is evidence of vascular compromise, the fracture should be reduced and pinned urgently and the limb reevaluated.

Question 172

Topic: Pediatric Upper Extremity & Spine

A 12-year-old girl who is 3 months postmenarchal undergoes full-time brace treatment for scoliosis. The posteroanterior radiograph (Figure A ) taken at that time reveals a right thoracic curve measures 28 degrees, and the left lumbar curve measures 23 degrees. At age 15, after 3 years of bracing, a repeat posteroanterior radiograph is obtained, now revealing a right thoracic curve measuring 11 degrees and the left lumbar curve measuring 19 degree, and Risser 4. Which statement best represents the indicated course of action in this patient? Review Topic

. Discontinuation of bracing as she has reached skeletal maturity.
. Continue full-time bracing until skeletal maturity.
. Continue nocturnal bracing until skeletal maturity.
. Posterior spinal fusion.
. MRI of the cervical, thoracic and lumbar spine.

Correct Answer & Explanation

. Discontinuation of bracing as she has reached skeletal maturity.

Explanation

This patient has adolescent idiopathic scoliosis (AIS) and has reached skeletal maturity. Bracing was successful and discontinuation of bracing is appropriate.Curves <25° can be treated with observation, while flexible curves from 25° to 45° in skeletally immature patients (Risser 0, 1, 2) should be treated with bracing. Bracing success is most commonly defined as <5° curve progression and failure is 6° or more curve progression at orthotic discontinuation (skeletal maturity), absolute progression to >45° either before or at skeletal maturity, or discontinuation in favor of surgery. Skeletal maturity is defined Risser sign 4, <1cm change in height over 2 visits 6 months apart, 2 years postmenarchal.Richards et al. attempted to define parameters for future AIS bracing studies. Outcome measures should include patients with (1) <5° curve progression vs >6° progression at maturity, (2) curves exceeding 45° at maturity, or those who have had surgery recommendation/undergone.Negrini et al. performed a Cochrane systematic review. Basing conclusions on 2studies, they found that (1) a brace treated curve progression (74% success) better than observation (34% success) and electrical stimulation (33% success), and (2) a rigid brace is more successful than an elastic one (SpineCor) at curbing curve progression.AisastandingPAradiographshowing.Incorrect

Question 173

Topic: Pediatric Upper Extremity & Spine
The Risser sign is one of the most commonly used markers for skeletal maturation and growth potential in patients with adolescent idiopathic scoliosis. What Risser sign has been shown to correlate with the greatest velocity of skeletal linear growth?
. Risser 0
. Risser I
. Risser II
. Risser III
. Risser IV

Correct Answer & Explanation

. Risser 0

Explanation

There are two stages of life where the velocity of postnatal skeletal growth is most rapid: during the first year of life and puberty. Both correlate with a Risser sign of 0. Risser 0 covers the first 2/3 of the pubertal growth spurt and correlates with the greatest velocity of skeletal linear growth. Risser grades range from 0 to V and are a measure of the progression of ossification in the pelvis. The Risser sign is usually referenced in clinical decision-making regarding adolescent idiopathic scoliosis. Biondi et al. examined 111 patients to determine the relationship between the accuracy of the Risser sign and bone age determinations. They found that the iliac crest apophysis maturation correlated with skeletal age assessment. They suggest that Risser sign is a reliable method for assessing skeletal bone age.

Question 174

Topic: Pediatric Upper Extremity & Spine

A 7-year-old boy is seen in the emergency department with an isolated and displaced supracondylar humerus fracture and absent radial and ulnar pulses. Despite a moderately painful attempt at realignment, examination reveals that his hand remains pulseless. What is the next most appropriate step in management? Review Topic

. Order an urgent angiogram and then proceed to the OR
. Repeat the reduction in the emergency department and reassess.
. Perform open reduction through an anterior approach.
. Perform closed reduction and pinning in the OR and reassess the vascular status.
. Perform arterial repair and then stabilize the fracture.

Correct Answer & Explanation

. Perform closed reduction and pinning in the OR and reassess the vascular status.

Explanation

Displaced supracondylar humerus fractures in children may have associated vascular compromise. Decreased blood flow may be due to vessel injury, entrapment within the fracture site, kinking from fracture displacement, or from vessel spasm. Optimal initial treatment in the emergency department includes gentle realignment of the limband vascular assessment. Angiography is not required in isolated injuries as the level of the vessel compromise is always at the site of the fracture. When blood flow is not restored, the next best step in treatment is to proceed urgently to the operating room. A formal closed reduction and pinning is performed, and then the vascular status is reassessed. Exploration and vascular repair is required if the hand is cool, white, and without pulses.

Question 175

Topic: Pediatric Upper Extremity & Spine

A 21-year-old right hand-dominant male collegiate swimmer reports painful clicking in the right shoulder. He states that he can occasionally feel his shoulder “slip out” when he is working out. AP, true AP, and axillary radiographs are shown in Figures 39a through 39c. What is the next most appropriate step in management? Review Topic

. Echocardiography
. Abdominal ultrasound
. Skeletal survey
. Glenoid osteotomy
. Physical therapy

Correct Answer & Explanation

. Echocardiography

Explanation

The radiographs show glenoid hypoplasia. The common radiographic findings of glenoid hypoplasia include an inferior and posterior glenoid deficiency, enlargement of the distal end of the clavicle, and sometimes an indentation in the glenoid. It is usually bilateral and rarely associated with other syndromes; therefore, an echocardiogram, abdominal ultrasound, or a skeletal survey is unnecessary unless the patient has stigmata of a syndrome such as Holt-Oram or Apert’s. Although posterior instability has been reported, the results of glenoid osteotomy have been variable and should not be considered initially. Physical therapy is the mainstay of initial management, but the patient should be counseled that this may be a recurrent problem with early osteoarthritis developing in many patients. Radiographs of the contralateral side should be obtained because this is usually bilateral.

Question 176

Topic: Pediatric Upper Extremity & Spine
A 21-year-old right hand-dominant male collegiate swimmer reports painful clicking in the right shoulder. He states that he can occasionally feel his shoulder “slip out” when he is working out. AP, true AP, and axillary radiographs are shown in Figures 39a through 39c. What is the next most appropriate step in management?
. Echocardiography
. Abdominal ultrasound
. Skeletal survey
. Glenoid osteotomy
. Physical therapy

Correct Answer & Explanation

. Physical therapy

Explanation

DISCUSSION: The radiographs show glenoid hypoplasia. The common radiographic findings of glenoid hypoplasia include an inferior and posterior glenoid deficiency, enlargement of the distal end of the clavicle, and sometimes an indentation in the glenoid. It is usually bilateral and rarely associated with other syndromes; therefore, an echocardiogram, abdominal ultrasound, or a skeletal survey is unnecessary unless the patient has stigmata of a syndrome such as Holt-Oram or Apert’s. Although posterior instability has been reported, the results of glenoid osteotomy have been variable and should not be considered initially. Physical therapy is the mainstay of initial management, but the patient should be counseled that this may be a recurrent problem with early osteoarthritis developing in many patients. Radiographs of the contralateral side should be obtained because this is usually bilateral. REFERENCES: Wirth MA, Lyons FR, Rockwood CA Jr: Hypoplasia of the glenoid: A review of sixteen patients. J Bone Joint Surg Am 1993;75:1175-1184. Smith SP, Bunker TD: Primary glenoid dysplasia: A review of twelve patients. J Bone Joint Surg Br 2001;83:868-872.

Question 177

Topic: Pediatric Upper Extremity & Spine
A 13-year-old girl with adolescent idiopathic scoliosis is otherwise healthy with a normal neurologic examination and she began her menstrual cycle 3 months ago. Standing radiographs show a high left thoracic curve from T1-T6 that measures 29 degrees, a right thoracic curve from T7-L1 that measures 65 degrees, and a left lumbar curve from L1-L5 that measures 31 degrees, correcting to 12, 37, and 10 degrees, respectively, on bending films. Her Risser sign is 1. What is the most appropriate management?
. Bracing
. Posterior spinal fusion of only the right thoracic curve
. Posterior spinal fusion from T2-L4
. Vertebral body stapling to halt progression of the curve
. Anterior and posterior spinal fusion

Correct Answer & Explanation

. Posterior spinal fusion of only the right thoracic curve

Explanation

The patient has typical adolescent idiopathic scoliosis with a right thoracic curve. This represents a Lenke-1B curve pattern; therefore, only treatment of the thoracic curve is required. The proximal thoracic and thoracolumbar curves are very flexible. The patient is Risser 1 and has just started her menstrual cycles; therefore, she is at significant risk for further curve progression. Bracing is not appropriate for a curve of this magnitude and will not halt the progression of this curve, nor will vertebral body stapling stop this curve. Vertebral body stapling is sometimes useful in small thoracic curves of less than 35 degrees and skeletally immature patients. Anterior and posterior spinal fusion is not required because the patient has no other risk factors, such as neurofibromatosis, nor is she at risk for crankshaft. Anterior fusion is an option, but it is not listed.

Question 178

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female (Risser stage 0) is diagnosed with adolescent idiopathic scoliosis (AIS). Standing posteroanterior radiographs reveal a right thoracic curve measuring 34 degrees. What is the most appropriate initial, evidence-based management strategy to prevent curve progression to surgical magnitude?

. Observation with repeat radiographs every 12 months
. Thoracolumbosacral orthosis (TLSO) bracing for at least 18 hours per day
. Intensive physical therapy utilizing the Schroth method exclusively
. Posterior spinal fusion with pedicle screw instrumentation
. Anterior vertebral body tethering

Correct Answer & Explanation

. Observation with repeat radiographs every 12 months

Explanation

According to the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST), TLSO bracing is indicated and highly effective for skeletally immature patients (Risser 0-2, premenarchal) with curves between 25 and 45 degrees. Bracing significantly decreases the progression of high-risk curves to the surgical threshold (generally >50 degrees).

Question 179

Topic: Pediatric Upper Extremity & Spine
A 13-year-old premenarchal female presents for routine evaluation of adolescent idiopathic scoliosis. Standing posteroanterior radiographs demonstrate a right thoracic curve measuring 35 degrees using the Cobb method. Her Risser stage is 1. What is the most appropriate management to halt curve progression?
. Observation with repeat radiographs in 6 months
. Physical therapy focusing on Schroth exercises
. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours per day
. Posterior spinal fusion with pedicle screw instrumentation
. Anterior vertebral body tethering

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours per day

Explanation

The indications for bracing in Adolescent Idiopathic Scoliosis (AIS) include a growing child (Risser stage 0-2, premenarchal or < 1 year postmenarchal) with a progressive curve between 25 and 45 degrees. The goal of bracing is to halt curve progression and prevent the need for surgery. Bracing for 16-23 hours per day (dose-dependent) with a rigid TLSO has been shown in the BRAIST trial to significantly decrease the rate of progression to the surgical threshold.

Question 180

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl with adolescent idiopathic scoliosis presents for evaluation. Standing radiographs show a right thoracic curve of 55°, a left lumbar curve of 35°, and a proximal thoracic curve of 20°. On side-bending films, the thoracic curve reduces to 30°, the lumbar curve to 15°, and the proximal thoracic to 10°. The apical lumbar vertebra is L2, and the center sacral vertical line (CSVL) touches the medial border of the left L2 pedicle. Sagittal T5-T12 kyphosis is +25°. Based on the Lenke classification, what is the correct curve type and modifier?

. 1AN
. 1BN
. 1CN
. 2BN
. 3CN

Correct Answer & Explanation

. 1AN

Explanation

The patient has a Lenke 1 (Main Thoracic) curve. The main thoracic curve is structural (>25° on bending). The lumbar curve is non-structural as it bends out to <25° (15°). The proximal thoracic is also non-structural (<25° on bending). The lumbar modifier is B because the CSVL falls between the lateral margin of the apical vertebral body and the medial border of the pedicle. The sagittal modifier is N (Normal, 10°-40°). Therefore, the classification is 1BN.

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