Don’t Forget the Brain Busters – Round 3 answers

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DFTB, T. Don’t Forget the Brain Busters – Round 3 answers, Don't Forget the Bubbles, 2019. Available at:
http://doi.org/10.31440/DFTB.24755

Here are the answers to the Minor Injuries Picture Quiz. How did you do?

 

Question 1

Sam, a 14-year old competitive sprinter, limps into your ED complaining of a severe pain in his left hip which came on suddenly while running. He points to a specific area of his pelvis and experiences pain on active hip flexion, which is weaker than on the right. This is his x-ray. What is his diagnosis?

Sam has a left-sided lesser trochanter avulsion fracture, caused by sudden contraction of the iliopsoas muscle during sprinting. There are many different pelvic apophyseal injuries, which range from recurring painful episodes of apophysitis to avulsion fractures of these secondary ossification centres. Avulsions often present with reports of a “pop” followed by severe pain and weight-bearing difficulties. There is a reported injury predominance in adolescent males of over 70%, with sports involving kicking or sprinting most likely to be involved. Early diagnosis and appropriate management is necessary to reduce the risk of chronic pain, disability and reduced participation in physical activity. Apophyseal injuries can be misdiagnosed as “muscle strains” due to a failure to appreciate the anatomical uniqueness of this population making their injury pattern distinct from that of adults. Most injuries are managed conservatively with initial rest and symptomatic support in the form of ice, protected weight-bearing and analgesia. Gradual reintroduction to weight-bearing with early range of motion (ROM) and strengthening should be progressed under the guidance of a physiotherapist. To read more about pelvic avulsion fractures in children, take a look at Owen’s pelvic avulsion injuries post

 

Question 2

Tom, a 5 year old boy, is brought to the ED after a football game with his 9-year old brother went pear-shaped. Tom, standing in goal, took the full brunt of a misjudged penalty shot. Luckily Tom did not lose consciousness and has not vomited but when he told his mum everything looked a bit blurry she panicked bundled him in the back of the car and drove straight to your ED. There is no evidence of bruising or contusion but when you assess Tom’s eye movements you see this when he looks up at the ceiling. What is this a sign of? What sensory loss might you see with this injury?

Image reproduced with permission from www.emj.bmj.com

 

Tom has a restriction of upward gaze of his right eye, a sign of entrapment of the right inferior rectus muscle trapped in a blowout fracture of the inferior orbital wall. Children with orbital floor fractures may not have any facial bruising, presenting classically with only a “white-eyed fracture”, the only sign being limitation of eye movement secondary to entrapment. Children with orbital floor or medial wall fractures are at a high risk of entrapment, as paediatric bones are more prone to greenstick fracture, which then creates a ‘trapdoor’ effect ensnaring the inferior oblique and inferior rectus muscles or other orbital contents. Entrapment is a surgical emergency, as ischaemia of the involved musculature can cause permanent damage. The infraorbital nerve is commonly damaged in these injuries, resulting in numbness to the ipsilateral cheek, lip and upper gum. To read more about orbital fractures, take a look at Orla’s orbital fractures post.

 

 

Question 3

Sebastian is a 13 year old boy who is the school basketball champion. During training, leapt to deliver a slam dunk but just as he lifted into the air felt a sudden pop in his right knee. He is unable to weight bear and when you examine him it’s immediately obvious that the right knee is swollen compared to the left. He cannot straight leg raise. This is his x-ray. What does it show? What can you measure to confirm your suspicion?

Case courtesy of Dr M Mourits, Radiopaedia.org. From the case rID: 14476

 

Sebastian’s left knee x-ray shows a large haemarthrosis and suspicion of patella alta (a high riding patella). You can measure the Insall-Salvati ratio: measure the length of the patella tendon (from the lower pole of the patella to the tibial insertion) and divide by the patella length (the longest measurement of the pole). If the ratio is >1.2, this is diagnostic of patella alta, suggestive of a patella tendon rupture. Patella tendon ruptures occur during forceful contraction of the quads muscle (usually while the foot is planted and knee flexed), e.g. missing a step while climbing stairs or in jumping sports. Conditions that cause microscopic damage to the tendon blood supply such as repeated microtrauma (e.g. athletes) predispose to rupture. The inability to actively straight leg raise is indicative of serious extensor mechanism pathology and should be assumed to be a tear until proven otherwise. While rare in children, delayed diagnosis causes increased morbidity. Conservative management with immobilisation with a removal knee splint in full extension may be considered for those children with only partial tears and an intact extensor mechanism. Surgical repair is indicated for complete tears. To read more about patella injuries, take a look at Tadgh’s all things patella post.

 

Question 4

Sophie is a 15 year old girl who was chasing her annoying 11 year old brother when she tripped over a rogue rugby ball and fell straight onto her outstretched left hand. Her left wrist is very sore and tender. This is her x-ray. What do you see?

 

Sophie has three fractures: a distal radius fracture (which may well be displaced on lateral view), an ulnar styloid fracture and a scaphoid fracture. Scaphoid fractures are uncommon in young children because the scaphoid is protected during its ossification by a thick layer of cartilage and soft tissue. However, as the child enters adolescence, bony scaphoid fractures become more common. They are classically seen after FOOSH (fall onto an outstretched hand) and punching injuries. Don’t be misled by distracting wrist pain; be sure to assess for tenderness in the anatomical snuffbox, tenderness of the scaphoid tubercle and pain on telescoping of the thumb. Scaphoid fractures are often missed on plain x-ray, so if a young person has clinical features of a scaphoid fracture without any radiological changes on plain film, treat as a fracture and organise follow-up. MRI is much more sensitive at detecting scaphoid fractures so some departments are now using MRI as first-line imaging for these injuries. To read more about scaphoid fractures, take a look at Sarah’s scaphoid fractures post.

 

Question 5

10 year old George was hurdling at school when he tripped and fell. He was seen at a neighbouring ED a couple of days ago who diagnosed a sprain of his knee but the pain is no better and his knee is so swollen that his mum has brought him to your ED for a second opinion. His knee exam is limited by pain. You order a knee x-ray. What do you spot?

Case courtesy of Dr Yuan Ling, Radiopaedia.org. From the case rID: 69680

 

There is mild cortical elevation at the inferior patella pole: George has a patella sleeve fracture. These account for over 50% of all patella fractures in children and are caused by indirect trauma to the knee and are the result of a forceful quads muscle contraction in a skeletally immature child. Inferior pole sleeve fractures are most common. Patella alta or patella baja (low lying patella) may be present if the inferior (alta) or superior (baja) tender is disrupted. If the fracture is nondisplaced (<2mm) then conservative management is adopted with a cylinder cast in extension. If the fracture is displaced (>2mm) an ORIF (open reduction and internal fixation) to repair the tendon is usually required.

 

Question 6

12 year old Ella was jumping on the trampoline when she took a tumble: she planted her foot, hyperextending her knee and twisted. Her knee is now super sore and very swollen. What can you see on her x-ray? (hint, the lateral is your friend here)

Ella has a tibial spine fracture. These can be pretty tricky to spot on AP views, slightly easier on the lateral (here you can see the fracture fragment in the joint space), but often an oblique will show the fracture more obviously. These fractures are due to avulsion at the insertion of the anterior cruciate ligament (ACL). They typically occur in adolescents between the 8-14 years of age, usually associated with a fall from a bicycle or pivoting on a planted foot while playing sport. With stress, the incompletely ossified tibial eminence in the child avulses before the ligament ruptures. Stability of the knee may be difficult to assess due to pain and muscle spasm but the anterior drawer and Lachman’s test may be positive. AP and lateral x-rays of the knee should be obtained. Complicated fractures will likely need further evaluation with CT or MRI to fully characterise the injury. Splint the knee in extension and discuss with your orthopaedic colleagues: displaced fractures may need operative repair.  To find out more about proximal tibial fractures, take a peek at Deirdre’s proximal tibial fractures post.

 

Question 7

Margot is 12 years old and a keen gymnast. She was practising on the uneven bars and had sudden pain in the medial aspect of her left arm during a twisting manoeuvre. Her elbow is swollen and tender medially and there appears to be some valgus laxity. This is her x-ray. What can you spot? (or not)

Margot has a medial epicondyle avulsion fracture.  This is where CRITOE comes into play: Margot is 12 years old and so should have all of her ossification centres visible – and they all are, all the way to the external (lateral) epicondyle. But what about her internal (medial) epicondyle? It is visible, it’s just in the wrong place. The yellow ring is where the internal epicondyle should be. It’s actually outlined in red, way away from where it’s meant to be. 

 

Medial epicondyle fractures occur between 7-15 years (they account for 10% of elbow fractures in children). They are often associated with elbow dislocation 50% of the time. The degree of displacement of the medial epicondyle needs to be assessed.

Undisplaced or minimally displaced (<5 mm) fractures will not need surgical repair and can be managed in a long arm backslab (with 90 degrees elbow flexion). Displacement of 5-15 mm requires ortho input – surgical intervention usually depends on multiple factors (e.g. age, dominant hand, sports involvement).  Displacement of >15 mm or neurovascular compromise (ulnar nerve palsy) will require ORIF. Take a look at Tessa’s CRITOE Quick Quiz for more CRITOE fun.

 

Question 8

14-year old Nicholas was out skateboarding. Super chuffed that he’d finally mastered the slide and grind, he went for a last good luck flip. Only it wasn’t so lucky – he landed on his forearm and swears he heard a crunch. His forearm is grossly swollen and incredibly sore but after some intranasal fentanyl he tolerates an x-ray. What does his x-ray show? 

Nicholas has a Monteggia fracture-dislocation: a fracture of the proximal ulna with associated dislocation of the radial head (that radio-capitellar line goes nowhere near the capitellum). Monteggia variants have a peak incidence in the 4-10 year olds and, although rare, missing one can have long-lasting consequences. Isolated midshaft ulna fractures are very rare in children: when an ulna fracture is identified you must also get an x-ray of the wrist and elbow joints. Monteggia fracture-dislocations are most commonly classified by the Bado Classification, which categorises these injuries into four categories depending on the direction of radial head dislocation. Type 1 injuries, like Nicholas’, consist of a proximal ulna fracture with anterior dislocation of the radial head, and are the most common, accounting for about 75% of all paediatric Monteggia fracture-dislocations. The priority is for urgent orthopaedic assessment; all require urgent reduction of the radial head dislocation. To read more about paediatric Monteggia fracture-dislocations, check out Rie’s Monteggia post.

 

Question 9

Rebecca is 13 years old. She was playing on her pogo stick but her right foot slipped off and she landed awkwardly on twisting and externally rotating her ankle. She immediately fell to the floor on the court and couldn’t stand on it. Her ankle is very bruised and swollen and, even after intranasal fentanyl, she is very reluctant to weight bear on it. What type of fracture does she have?

Rebecca has a Salter-Harris III of her distal tibia with avulsion of the anterolateral corner of the distal tibial epiphysis, known as a Tillaux fracture. Salter-Harris III and IV fractures of the ankle are relatively common in adolescents because the lateral and deltoid ligaments are stronger than the physis itself. Tillaux fractures require an open tibial physis; the distal tibial physis closes initially centrally, then medially and finally laterally. Tillaux fractures are caused by rotational injuries, causing avulsion of the lateral part of the distal tibial physis by the anterior inferior tibulofibular ligament (and are therefore different from Pilon fractures which are axial compression injuries). An important differential diagnosis in an adolescent is a Triplanar fracture, which is very similar to a Tillaux fracture but has an additional direction of fracture in the coronal plane, evident on lateral ankle x-ray or CT. Triplanar fractures have three directions of fracture (much like the Mercedes sign, which is what they can look like on CT): a vertical fracture through the epiphysis, a horizontal fracture through the physis and an oblique fracture through the metaphysis. To read more about interpreting paediatric ankle x-rays, have a look at Tessa’s ankle x-ray interpretation post

 

We hope you enjoyed the minor injuries picture round. Next up: the emoji round.

 

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