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Pediatric Upper Extremity & Spine MCQs

Practice Set 11 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 201

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for adolescent idiopathic scoliosis (AIS), which of the following criteria determines whether a secondary (minor) curve is considered 'structural' and therefore necessitates inclusion in the fusion construct?

. Cobb angle > 15 degrees on standing PA radiograph
. Cobb angle > 25 degrees on side-bending radiographs
. Apical vertebral translation > 2 cm
. Nash-Moe rotation of grade II or higher
. Presence of a concomitant kyphosis > 10 degrees

Correct Answer & Explanation

. Cobb angle > 25 degrees on side-bending radiographs

Explanation

According to the Lenke classification of AIS, a minor curve is considered structural if it fails to correct to < 25 degrees on supine side-bending radiographs, or if there is regional kyphosis > 20 degrees. Structural minor curves must generally be included in the surgical fusion construct to achieve optimal coronal and sagittal balance.

Question 202

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 203

Topic: Pediatric Upper Extremity & Spine

Examination of a 5-year-old boy with amyoplasia shows a flexion contracture of 70 degrees of the right knee. The active arc of motion is from 70 degrees to 90 degrees, and the opposite knee has a flexion contracture of 10 degrees. Both hips are dislocated with flexion contractures of 10 degrees, passive hip motion is from 10 degrees to 90 degrees of flexion, and the feet are plantigrade and easily braceable. Despite a daily stretching program, the parents and physical therapists note that it is increasingly difficult for him to walk because of the flexion contracture of the right knee. Management of the knee flexion contracture should now include

. intense physical therapy.
. an intramuscular injection of botulinum toxin A.
. radical posterior soft-tissue release.
. supracondylar femoral extension osteotomy.
. gradual correction with a circular ring external fixator.

Correct Answer & Explanation

. radical posterior soft-tissue release.

Explanation

Most children with amyoplasia are ambulatory and when a decrease in function occurs because of a severe contracture, it must be addressed. A radical posterior soft-tissue release, including the posterior knee capsule and often the collateral ligaments and the posterior cruciate ligament, is needed to obtain extension. After the age of 1 year, aggressive physical therapy will do little to correct a contracture. Botulinum toxin A is indicated for spasticity and is contraindicated with severe contractures. Supracondylar femoral extension osteotomy works well, but will remodel at an average rate of 1 degree per month, which is not considered ideal in a young patient. Gradual correction with a circular ring external fixator is an option, but a soft-tissue release will also most likely be needed for a contracture of this severity. Sarwark JF, MacEwen GD, Scott CI Jr: Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 1990;72:465-469. DelBello DA, Watts HG: Distal femoral extension osteotomy for knee flexion contracture in patients with arthrogryposis. J Pediatr Orthop 1996;16:122-126.

Question 204

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 Figures 6a and 6b. 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

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. Cramer KE, Green NE, Devito DP: Incidence of anterior interosseous nerve palsy in supracondylar humerus fractures in children. J Pediatr Orthop 1993;13:502-505.

Question 205

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

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. 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.

Question 206

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

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. 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.

Question 207

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female presents for operative evaluation of adolescent idiopathic scoliosis. Standing full-length spine radiographs show a main thoracic curve of 55 degrees and a lumbar curve of 35 degrees. The proximal thoracic curve is 20 degrees. On side-bending radiographs, the main thoracic curve corrects to 30 degrees, the lumbar curve corrects to 15 degrees, and the proximal thoracic curve corrects to 5 degrees. Based on the Lenke classification, what is the correct curve type?

. Type 1 (Main Thoracic)
. Type 2 (Double Thoracic)
. Type 3 (Double Major)
. Type 4 (Triple Major)
. Type 5 (Thoracolumbar/Lumbar)

Correct Answer & Explanation

. Type 1 (Main Thoracic)

Explanation

In the Lenke classification system, a curve is considered structural if it fails to correct to < 25 degrees on side-bending radiographs or has an associated regional kyphosis > +20 degrees. Here, the lumbar curve corrects to 15 degrees (non-structural) and the proximal thoracic corrects to 5 degrees (non-structural). The main thoracic curve is the major curve (largest magnitude, 55 degrees). A major main thoracic curve with non-structural minor curves is classified as a Lenke Type 1.

Question 208

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a severe extension-type supracondylar humerus fracture after a fall. Radiographs classify it as a Gartland Type III. The distal fragment is severely displaced posteromedially relative to the proximal shaft. Based on this specific displacement pattern, which of the following nerve structures is at greatest risk of tethering or injury from the proximal fragment?
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Radial nerve
. Musculocutaneous nerve
. Posterior interosseous nerve (PIN)

Correct Answer & Explanation

. Radial nerve

Explanation

In an extension-type supracondylar humerus fracture, the displacement of the distal fragment dictates the direction of the proximal spike. If the distal fragment is displaced posteromedially, the sharp proximal fragment is thrust anterolaterally, placing the radial nerve at the highest risk of injury. Conversely, if the distal fragment displaces posterolaterally, the proximal spike goes anteromedially, placing the median nerve (and AIN) at greatest risk.

Question 209

Topic: Pediatric Upper Extremity & Spine

A 12-year-old premenarchal female is evaluated for Adolescent Idiopathic Scoliosis (AIS). She has a right thoracic curve. Her Risser stage is 0. Based on SRS (Scoliosis Research Society) guidelines, which of the following is the primary indication for initiating full-time bracing treatment?

. Curve magnitude of 15 to 20 degrees with documented progression of 5 degrees
. Any curve greater than 45 degrees regardless of progression
. Curve magnitude of 20 to 25 degrees at initial presentation
. Curve magnitude of 25 to 45 degrees with documented progression, or initial curve 30 to 39 degrees
. Curve magnitude of 10 degrees combined with a positive family history

Correct Answer & Explanation

. Curve magnitude of 25 to 45 degrees with documented progression, or initial curve 30 to 39 degrees

Explanation

The SRS guidelines for bracing in AIS include patients who are skeletally immature (Risser 0-2, premenarchal) with a curve of 25 to 29 degrees that has documented progression of 5 degrees or more, or an initial presentation with a curve between 30 and 39 degrees. Curves > 45-50 degrees are generally indications for surgery, while curves < 25 degrees without documented progression are observed.

Question 210

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl falls on an outstretched hand and sustains a completely displaced, extension-type supracondylar humerus fracture (Gartland Type III). On physical examination, she cannot actively flex the interphalangeal joint of her thumb or the distal interphalangeal joint of her index finger. Which specific nerve structure is most likely injured?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve (AIN)
. Posterior interosseous nerve (PIN)
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

The anterior interosseous nerve (AIN), a motor branch of the median nerve, is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures (particularly with posterolateral displacement). It innervates the flexor pollicis longus (FPL), the radial half of the flexor digitorum profundus (FDP), and the pronator quadratus. Deficits manifest clinically as the inability to form an 'OK' sign.

Question 211

Topic: Pediatric Upper Extremity & Spine
According to the Lenke classification system for Adolescent Idiopathic Scoliosis (AIS), curve flexibility is a key determinant in selecting fusion levels. A scoliotic curve is defined as 'structural' if it meets which of the following radiographic criteria on coronal side-bending films?
. Cobb angle corrects to less than 25 degrees
. Cobb angle fails to correct to less than 25 degrees
. Apical vertebral translation is greater than 2 cm
. Thoracic kyphosis (T2-T12) measures greater than +40 degrees
. Apical vertebral rotation is Nash-Moe Grade III or higher

Correct Answer & Explanation

. Cobb angle fails to correct to less than 25 degrees

Explanation

In the Lenke classification of AIS, the distinction between a major/structural curve and a minor/non-structural curve dictates the levels to be fused. A curve is considered 'structural' if the Cobb angle remains at 25 degrees or greater on a maximum voluntary supine side-bending radiograph. Additionally, regional sagittal kyphosis of >= +20 degrees also defines a proximal thoracic or main thoracic curve as structural.

Question 212

Topic: Pediatric Upper Extremity & Spine
A 6-year-old child sustains a completely displaced Gartland Type III extension-type supracondylar humerus fracture. The anterior interosseous nerve (AIN) is anatomically at the highest risk for injury in this specific fracture pattern. Which of the following physical exam findings definitively confirms an isolated AIN palsy?
. Inability to forcefully abduct the fingers
. Numbness over the dorsal aspect of the first web space
. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger
. Inability to actively extend the wrist and metacarpophalangeal joints
. Loss of two-point discrimination on the volar aspect of the little finger

Correct Answer & Explanation

. Inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger

Explanation

The anterior interosseous nerve (AIN) is a purely motor branch of the median nerve that is frequently stretched or tethered over the proximal fracture fragment in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index (and sometimes middle) finger, and the pronator quadratus. An isolated AIN palsy manifests as the inability to form an 'OK' sign, presenting as a 'pinch' posture with the thumb IP and index DIP joints extended.

Question 213

Topic: Pediatric Upper Extremity & Spine
A patient sustained a C6 burst fracture in a diving accident. On initial neurological examination in the ICU, he demonstrates active wrist extension against gravity (Grade 3/5) but no active triceps or hand intrinsic function. He has no voluntary anal contraction, but he has preserved sensation to pinprick in the perianal area (S4-S5). Additionally, he has trace voluntary movement of his right great toe (Grade 1/5). According to the ASIA Impairment Scale (AIS), how should this patient be classified?
. AIS A
. AIS B
. AIS C
. AIS D
. AIS E

Correct Answer & Explanation

. AIS C

Explanation

The ASIA Impairment Scale classifies spinal cord injuries. The presence of ANY sacral sparing (perianal sensation or voluntary anal contraction) means the injury is incomplete (eliminating AIS A). Because there is motor function preserved more than 3 levels below the motor level (trace toe movement), the patient is motor incomplete. To differentiate between AIS C and AIS D, one evaluates the muscle grades below the neurological level: in AIS C, less than half of key muscle functions below the neurological level have a muscle grade of ≥ 3. In AIS D, at least half have a grade of ≥ 3. Since this patient only has trace (Grade 1) distal motor function, he is AIS C.

Question 214

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains a completely displaced, extension-type supracondylar humerus fracture (Gartland Type III). During your neurologic examination in the emergency department, you ask the child to make an 'OK' sign with his hand, but he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which nerve is most likely injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Posterior interosseous nerve (PIN)
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

The anterior interosseous nerve (AIN), a motor branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures (particularly those that displace posterolaterally). It innervates the flexor pollicis longus (FPL), the radial half of the flexor digitorum profundus (FDP to index and middle fingers), and the pronator quadratus. An AIN palsy clinically presents as the inability to form an 'OK' sign (pincer grasp) due to weakness of the FPL and FDP.

Question 215

Topic: Pediatric Upper Extremity & Spine

You are evaluating a 14-year-old female with Adolescent Idiopathic Scoliosis (AIS) to determine surgical fusion levels. According to the Lenke classification system, a proximal thoracic curve is defined as 'structural' (and thus typically requires inclusion in the fusion construct) if the Cobb angle on side-bending radiographs is at least:

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

In the Lenke classification for adolescent idiopathic scoliosis, a minor curve is considered 'structural' if it does not bend out to less than 25 degrees on coronal side-bending radiographs, or if there is kyphosis of at least +20 degrees across the regional segments. Identifying structural minor curves is critical, as the general rule is to include all structural curves in the fusion construct.

Question 216

Topic: Pediatric Upper Extremity & Spine
A 5-year-old girl falls off monkey bars and presents with a Gartland type III extension-type supracondylar humerus fracture. The hand is pink, well-perfused, but she is unable to flex the interphalangeal joint of her thumb and the distal interphalangeal joint of her index finger. Which of the following nerve structures has most likely been injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve
. Musculocutaneous nerve
. Recurrent motor branch of the median nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN), a motor branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus, the lateral half of the flexor digitorum profundus (index and middle fingers), and the pronator quadratus. Clinically, AIN function is assessed by having the patient form an 'OK' sign. Failure to do so (resulting in a flattened pinch mechanism) indicates an AIN palsy.

Question 217

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a completely displaced (Gartland Type III) supracondylar humerus fracture. Radiographs reveal that the distal fracture fragment is displaced posterolaterally. Given this specific displacement pattern, which nerve is at the highest risk of injury?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

In a posterolateral displaced supracondylar humerus fracture, the proximal fragment is driven anteromedially. This specific vector threatens the median nerve (and its anterior interosseous nerve branch) as well as the brachial artery. Conversely, in a posteromedial displacement pattern, the proximal fragment displaces anterolaterally, putting the radial nerve at the greatest risk.

Question 218

Topic: Pediatric Upper Extremity & Spine
A 6-year-old female falls from monkey bars and sustains a Gartland type III extension-type supracondylar humerus fracture. On examination, the hand is pink and well-perfused, but the radial pulse is absent. What is the next best step in management?
. Immediate open reduction and brachial artery exploration
. Urgent closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Observation and casting in situ
. Administration of intra-arterial vasodilators

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

A "pulseless, pink" hand after a displaced supracondylar humerus fracture indicates adequate collateral circulation. The next best step is urgent closed reduction and percutaneous pinning, as reduction often relieves kinking of the brachial artery and restores the pulse.

Question 219

Topic: Pediatric Upper Extremity & Spine

A 7-year-old boy presents with left elbow pain and swelling following a fall from a monkey bar. Radiographs reveal a Gartland Type II supracondylar humerus fracture. His radial pulse is palpable and strong, and he has no neurological deficits. What is the MOST appropriate initial management?

. Open reduction and internal fixation (ORIF)
. Closed reduction and long arm cast immobilization in hyperflexion
. Closed reduction and percutaneous pinning
. Sling immobilization alone
. Observe for 24 hours

Correct Answer & Explanation

. Closed reduction and percutaneous pinning

Explanation

A Gartland Type II supracondylar humerus fracture is displaced posteriorly with an intact posterior cortex, making it inherently unstable. Given the displacement, closed reduction and percutaneous pinning (CRPP) is the treatment of choice. This provides stable fixation while preserving the biology and allows for early mobilization to prevent stiffness. Closed reduction and casting in hyperflexion is an older technique with risks of neurovascular compromise and redisplacement. ORIF is reserved for irreducible fractures or those with open wounds. Sling immobilization is for non-displaced fractures (Type I). Observation is inappropriate for a displaced fracture.

Question 220

Topic: Pediatric Upper Extremity & Spine
A 10-year-old boy falls off a bicycle, sustaining a completely displaced supracondylar humerus fracture (Gartland Type III). He has a palpable radial pulse, but is unable to extend his fingers and has numbness in the distribution of the median nerve. Which of the following is the most urgent next step?
. Obtain an orthopedic consultation for closed reduction and percutaneous pinning.
. Perform an urgent nerve conduction study.
. Administer corticosteroids to reduce swelling.
. Observe for 24 hours to see if neurological symptoms improve.
. Order an MRI to assess nerve injury.

Correct Answer & Explanation

. Obtain an orthopedic consultation for closed reduction and percutaneous pinning.

Explanation

A completely displaced supracondylar humerus fracture (Gartland Type III) requires urgent reduction and fixation due to the high risk of neurovascular compromise and development of Volkmann's ischaemic contracture. The presence of median nerve palsy, even with a palpable radial pulse, indicates significant injury and potential for further compromise. Urgent closed reduction and percutaneous pinning (CRPP) is the treatment of choice. Restoration of anatomical alignment often resolves or improves nerve deficits and protects the vascular supply. Delay can lead to irreversible damage. Nerve conduction studies or MRI are not needed urgently and would delay critical intervention. Corticosteroids are not indicated. Observation is dangerous and inappropriate.

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