Carpal injuries

Cite this article as:
Sian Edwards. Carpal injuries, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.29050

Injuries to the hands are extremely common in children and are a frequent reason for their attending the ED. While common, their management can be limited by difficulties in proper assessment as well as a paucity of evidence to guide treatment. That said, documented outcomes remain typically excellent so it seems we must be doing something right! Generally, training is provided with an adult focus, and while some principles from adult trauma can be applied, it is not uniform. As our post on radiographic findings demonstrates, the bones of children are different. This is significant because we know that missed injuries or delays in appropriate treatment can lead to long term loss of function; further compounded by the science that children heal faster and therefore our window for intervention is considerably shorter. Therefore, accurate assessment coupled with appropriate initial management and timely referral if necessary are essential.

As is not uncommon in the paediatric arena, evidence specific to this population is limited although it is stated that carpal fractures in children are being increasingly reported . Perhaps this is as we, as clinicians, get better at diagnosis and radiologists therefore see more and so naturally become more adept at interpreting them. Regardless of radiographic findings, diagnosis is primarily through clinical examination. 

While not exclusive to the teenage population, we can expect the majority of carpal injuries to occur in the older child; as children age, become braver and take on more activities with an increased likelihood of higher velocity falls. Falling onto an outstretched hand, otherwise widely known as a FOOSH injury, is a common mechanism, accounting for 30% of non-scaphoid carpal injuries.

Before we get in to it, we can take a moment to re-familiarise ourselves with the bones of the hand and wrist.

The carpus

The carpal bones are the eight bones of the wrist that articulate the forearm with the hand – this in itself seems confusing as they are quite clearly situated in what we call the hand but go with it. They are divided into the proximal and distal rows, collectively known as the carpus. Proximally we have scaphoid, lunate, triquetrum, pisiform and distally, trapezium, trapezoid, capitate, hamate. The carpal bones develop through the course of childhood and should all be visible on X-ray by approximately 8 years of age.

Literature suggests that carpal fractures account for around 8-19% of all hand injuries worldwide; as we’ve already touched on, the majority will be scaphoid fractures and ED’s are pretty used to dealing with these – they even get their own series of x-rays – for that reason, this post will give some time to carpal fractures NOT including the scaphoid.

What are we looking for on x-ray?

While the AP view allows clear visualization of all of the carpal bones and would appear the ‘easier’ view, particularly to those less experienced with interpreting these x-rays, the lateral view is good for assessing the distal wrist, carpal bones and proximal metacarpals – it can appear confusing at first due to the overlapping bones. Regardless, both radiographs must be evaluated together. As always, we are tracing each individual bone looking for obvious breaks in the cortex before then looking for uniformity of the joint spaces; abnormally widened spaces are often indicative of ligamentous injury however abnormally narrow spaces are often the result of radiographic projection rather than injury. It is often helpful to sit back from the image and see it in its entirety as well as a close-up view.

Image adapted from a case courtesy of Dr Jeremy Jones, Radiopaedia.org. From the case rID: 37947

Recommended questions to ask when looking at the carpal bones:

  • Is the scapho-lunate distance less than 2mm wide? – if NO then suspect a tear of this ligament.
  • Is there a bony fragment lying posterior to the carpal bones? if YES, then suspect triquetral fracture.
  • Is there a bone sitting in the cup of the lunate? If NO, think carpal dislocation involving the lunate.

After the scaphoid bone, the triquetrum is the most commonly fractured bone in isolation with the trapezoid bone being the least frequently fractured. Each will now get it’s moment to shine as we take a minute to go through them.

Triquetral

Triquestral
Triquetral bone

Triquetral fractures usually occur on the dorsal aspect of the bone and are often the result of perilunate fracture dislocation as well as fracture of distal radius and ulna; they account for about 20% of all carpal fractures and are regularly missed.  These may occur by means of impingement from ulnar styloid, shear forces or avulsion from strong ligamentous attachments. The usual mechanism is a FOOSH whilst in ulnar deviation, and less commonly a direct blow to the dorsum of the hand. It is best seen on a lateral projection where the avulsed flake of bone may be seen lying posteriorly to the triquetrum – look for pooping duck sign on the image.

Image adapted from a case courtesy of Dr Maulik S Patel, Radiopaedia.org. From the case rID: 16046
Case courtesy of Dr Matt Skalski, Radiopaedia.org. From the case rID: 57109

Hamate

The hamate

Hamate fractures are rare, only accounting for approximately 2% of carpal fractures, potentially due to under reporting. They generally don’t happen in isolation, often being associated with dorsal fracture dislocation of 4th and 5th carpometacarpal (CMC) joints, ulnar nerve injury and flexor tendon rupture, especially of 4th and 5th fingers. Common mechanisms are from blunt trauma e.g. fist punch, falls and through impact from racquet sports.

Image adapted from a case courtesy of Andrew Murphy, Radiopaedia.org. From the case rID: 46110

Capitate

Capitate

Like hamate fractures, capitate fractures are also frequent injuries which seldom occur in isolation. A capitate fracture is uncommon, accounting for approximately 1.3% of carpal fractures and can be associated with a scaphoid fracture. It is uncommon to have a combined capitate-hamate fracture. The primary mechanism is a FOOSH with the wrist in hyperextension. Injury can result in ‘scaphoid capitate’ syndrome (1-2% incidence) where the capitate actually rotates by 180o – this latter presentation will need open reduction.

Image adapted from a case courtesy of Dr Bahman Rasuli, Radiopaedia.org. From the case rID: 65954

Lunate

Lunate

Lunate fractures account for about 1% of carpal fractures, and like its predecessors rarely occur independently. They are associated with injuries to the distal radius, carpus or metacarpals. Subluxations / dislocations of the carpus are most commonly centred around the lunate bone and key to their detection is the apple, cup, saucer analogy- the cup of the lunate should never be empty – the distal radius, lunate and capitate articulate with each other in a straight line on the lateral radiograph, so when examining the image, if the capitate (apple) is not sitting in the cup of the lunate on the saucer of the radius then injury is present. Failure to recognise this anatomy means that dislocations are often overlooked. Where scapho-lunate ligament injury has occurred, missed diagnosis can lead to chronic pain around the joint due to its instability. In the younger population, surgery will be considered to restore full function and relieve pain.

Normal capitate – lunate – radius alignment. Image adapted from a case courtesy of Dr Jeremy Jones, Radiopaedia.org. From the case rID: 37947
Perilunate dislocation. Image adapted from a case courtesy of Dr Ian Bickle, Radiopaedia.org. From the case rID: 46714
Image adapted from a case courtesy of Dr Henry Knipe, Radiopaedia.org. From the case rID: 70427

More commonly, injury can occur at the scapho-luncate ligament – on x-ray, expect to see a widened joint space which is often referred to as the “Terry Thomas” or “Madonna” sign (named for the gap between the front teeth) demonstrating such injury. While conservative management may often be trialled, surgical reconstruction can be needed.

Image adapted from a case courtesy of Dr Ian Bickle, Radiopaedia.org. From the case rID: 46695

Trapezium

Trapezium

Trapezium fractures comprise between 3% and 5% of all carpal fractures and <1% of all hand injuries; they can occur in isolation or in combination with another carpal bone e.g. fracture of the 1st metacarpal base and/or subluxation or dislocation of the 1st carpometacarpal (CMC) joint although this is extremely rare. They are often the result of high energy trauma, usually involving axial loading force. Isolated trapezium fractures can be easily missed on x-ray due to the overlying bones, particularly on AP view.

Image adapted from a case courtesy of Amanda Er, Radiopaedia.org. From the case rID: 74739

Pisiform

Pisiform

Pisiform fractures account for 0.2% of all carpal fractures and of those, half are in association with other carpal injuries; rarely it may dislocate without fracture and displace radially. Its rarity is attributed to the sturdy ligaments that encase it.

Image adapted from a case courtesy of Dr Garth Kruger, Radiopaedia.org. From the case rID: 29263

Trapezoid

Trapezoid bone

Trapezoid fractures are incredibly rare, with only about 10 cases reported in the literature. Their anatomic location and stable articulation with the 2nd metacarpal together with their strong ligamentous attachments to neighbouring carpal bones are thought to be responsible for the low incidence of fracture.

Image adapted from a case courtesy of Dr Bruno Di Muzio, Radiopaedia.org. From the case rID: 46412

So how do we manage these injuries?

Inevitably there will be some local differences, but the general principles are:

  • Closed manipulation can prove difficult and often unsuccessful so orthopaedic review is required if displacement exists.
  • If no displacement, and no concern about ligamentous injury, then conservative management is often indicated. There is frequently no requirement to formally immobilise so analgesia may be the only treatment. 
  • If carpal subluxation is suspected, always refer to the orthopaedic team for specialist evaluation. If you are unsure, the literature discusses obtaining a radiograph of the uninjured hand to use as comparison – this is not always a well received request so do consider utilising your local reporting radiologist, and if unavailable or in doubt then refer for follow up.

The take home

So, what essentially is our take home message? We need to keep in mind that carpal fractures, dislocations and ligamentous injuries do occur in children, albeit rarely. We need the ability to recognise the ‘normal’ so we can pick out the ‘abnormal’. As with all injuries, diagnosis should be mainly clinical with the x-ray being our confirmation. As cannot be said enough, if it presents like a fracture, or considerations of acute injury like swelling and pain inhibit your ability to confidently exclude it, then treat it as such and refer onwards to the specialists that can!

References

Armstrong M and Oyinkansola Adeogun BS (2009). Tendon injuries in the Pediatric Hand. The Journal of Craniofacial Injury. 20(4) : 1005-1010.

El-Feky M and Weerakkody Y (a). Trapezium fracture, accessed from https://radiopaedia.org/articles/trapezium-fracture?lang=gb accessed on 30/06/2020.

El-Feky M and Weerakkody Y (b). Pisiform fracture accessed from https://radiopaedia.org/articles/pisiform-fracture?lang=gb accessed on 30/06/2020.

Filho, R. L. R. et al. (2020). Capitate and Hamate Fracture. Case Study. Ortopedia, traumatologia, rehabilitacja. 22(2), pp. 143–149. doi: 10.5604/01.3001.0014.1185.

Foley K and Patel S (2012). Fractures of the scaphoid, capitate and triquetrum in a child: a case report. Journal of Orthopaedic Surgery. 20(1): pp 103-104.

Hacking C and Knipe H (). Carpometacarpal joint dislocation accessed from https://radiopaedia.org/articles/carpometacarpal-joint-dislocation?lang=gb accessed on 12/06/2020

Hacking C and Radswiki et al. Triquetral Fracture. Accessed from https://radiopaedia.org/articles/triquetral-fracture?lang=gb accessed on 30/06/2020.

Kam MLW, Sreedharan S, Teoh LC and Chew WYC (2011) ‘Severe Isolated Trapezoid Fracture:: A Case Report’, Hand Surgery, 16(2), pp. 185–187. doi: 10.1142/S0218810411005321.

Kose, O., Keskinbora, M. and Guler, F. (2015) ‘Carpometacarpal dislocation of the thumb associated with fracture of the trapezium’, Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology, 16(2), pp. 161–165. doi: 10.1007/s10195-014-0288-9.

Maloney E, Zbojniewicz A, Nguyen J, Luo Y and Thapa M (2018). Anatomy and injuries of the paediatric wrist: beyond the basics. Pediatric Radiology. 48 : pp764-782.

Murphy A and Knipe H. Hamate fractures. Accessed from https://radiopaedia.org/articles/hook-of-hamate-fracture?lang=gb accessed on 30/06/2020.

Raghupathi AK, Kumar P (2014). Nonscaphoid Carpal Injuries – Incidence and associated injuries. Journal of Orthopaedics. II: 91-95.

Rasoli, S., Ricks, M. and Packer, G. (2012) ‘Isolated displaced non-union of a triquetral body fracture: a case report’, Journal of medical case reports, 6, p. 54. doi: 10.1186/1752-1947-6-54.

Shah S, Rochette L and Smith G (2012). Epidemiology of pediatric hand injuries presenting to United States emergency departments, 1990-2009. Journal of Trauma and Acute Care. 72(6) : pp 1688-1694.

Wahba G and Cheung K (2018). Paediatric hand injuries: clinical review. Canadian Family Physician. 64: pp 803-810.

Scaphoid Fractures

Cite this article as:
Sarah Perkin. Scaphoid Fractures, Don't Forget the Bubbles, 2019. Available at:
https://doi.org/10.31440/DFTB.20952

Natasha,  a 13-year old girl, attends the Emergency Department with pain in the right wrist after falling onto her outstretched hand whilst ice skating. There is minimal swelling, but she is reluctant to move the wrist. She is tender on palpation of the anatomical snuffbox and on telescoping of the thumb. A senior colleague suggests this could be a scaphoid fracture and advises some plain radiographs. These show no bony injury, so she is placed in a wrist splint and referred for outpatient follow-up with the orthopaedic surgeons.

 

What is the scaphoid?

The scaphoid lies between the proximal and distal rows of carpal bones, on the radial side of the wrist. Its name comes from the Greek ‘skaphos’, meaning boat, due to its boat-like shape. It starts to ossify between the ages of four and six years, forming two poles (proximal and distal) united by the waist. Ossification occurs from the distal pole and moves proximally. During ossification, it is protected by cartilage. The scaphoid receives its blood supply from the branches of the radial artery, but due to retrograde flow, the blood supply can be interrupted when the bone is fractured, risking avascular necrosis.  Full ossification is usually complete by age 13 in girls and 15 in boys.

 

How common is scaphoid fracture in children?

Scaphoid fractures are uncommon in young children, due to protection of the bone during its ossification by a thick layer of cartilage and soft tissue. Cartilaginous fractures are possible but require reasonable force; simple soft tissue injuries are more common in younger age groups. Bony scaphoid fractures are seen predominantly in older children (ages 12-15). Any fracture diagnosed in the presence of growth plates seen elsewhere on radiographs are classified as paediatric fractures.

 

Mechanism of Injury:

 The injury pattern for scaphoid fractures is similar to that of adults, with the typical presentation being a fall onto an outstretched hand. Scaphoid fractures may also result from punching against resistance. This injury should also be considered in higher impact trauma, where the wrists are forcefully hyperextended against resistance; a child putting their arms out against a dashboard or front seat in the context of a car accident may lead to scaphoid fracture.

 

Examination Findings:

As with any orthopaedic examination, it is time to use the principle of look, feel and, finally, move.

As well as examining the distal radius and ulna, any wrist examination should include consideration of the scaphoid as the area of injury.

Although there is no positive finding which is pathognomonic of a scaphoid fracture, there are clues which should increase our clinical suspicion (see below)

Tenderness in the anatomical snuffbox – located in the first web space.

Tenderness of the scaphoid tubercle – located on the proximal palm at the base of the thumb

Pain elicited on axial loading, or ‘telescoping’ of the thumb.

Bear in mind that other injuries may be present.

Children can be difficult to assess, and if they are behaving as though they have a fracture, it can be difficult to rule out anything based on examination alone. Have a low threshold for imaging an area in which you are suspicious of a bony injury.

 

Imaging:

NICE recommends MRI as the first line imaging modality in suspected scaphoid fractures. MRI is not only expensive, but most emergency departments have restricted access to this investigation. Plain radiographs miss up to 25% scaphoid fractures across all age groups (Pincus, 2009), but this is our most readily available test.

A scaphoid series of plain x-rays includes four views: postero-anterior (PA), pronated, lateral, and supinated. A further view, PA with a clenched fist, allows some assessment of the scapholunate ligament integrity – although soft tissues cannot reliably be assessed on plain radiographs, a widened space between the scaphoid and lunate may suggest ligamentous disruption.

 

Plain x-rays are very specific – the presence of a cortical interruption or trabecular abnormality is highly likely to represent a true fracture. However, a normal radiograph is not sensitive enough to rule out a fracture. Patients with normal radiographs, in the presence of clinical symptoms or signs suggestive of a fracture, should be treated as such, and require further imaging, either in the form of repeat films 10-14 days post-injury, or an early MRI.

 

Fracture Patterns in Children:

Due to the scaphoid ossifying from the distal pole proximally, this is the most likely part of the bone to fracture first in children (Gajdobranski, 2014). Unlike in adults, the middle and proximal parts of the bone are less frequently encountered. Similar to other fractures in paediatric patients, scaphoid fractures in this younger age group may be incomplete (uni-cortical) or non-displaced.

 

Management:

There is some overlap in the management in of suspected and confirmed scaphoid fractures based on the initial x-ray.

Paracetamol, ibuprofen and elevation in a sling are all appropriate whilst waiting for radiology.

If there is a confirmed fracture seen on the patient’s initial imaging, they can have a scaphoid cast applied. This is a below elbow backslab with a thumb spica. These patients should be referred to the fracture clinic for further management.

 

Normal plain radiographs do not exclude a fracture. In this instance, a wrist splint is appropriate to immobilise the affected area. There is no evidence for splinting with the thumb in extension (Dawson-Bowling, 2014). These patients need to be brought back to the fracture clinic for repeat radiography, or more advanced imaging in the form of MRI, dependent on local protocols.

Most scaphoid fractures in children and teenagers are managed conservatively with a cast. Whilst immobilisation time is usually the final remit of the orthopaedic surgeons, it is helpful to be able to offer children and their parents some advice in the Emergency Department as to how long healing will take. As a rule, the more distal the fracture, the quicker the healing process. This is in part due to the blood supply of the scaphoid. Longer immobilisation times will be needed for middle and proximal fractures.

Occasionally, surgical fixation will be required for significantly displaced fractures, or in cases on non-union. This is beyond the scope of Emergency Department management.

 

Do not miss scaphoid fractures on wrist x-rays – don’t be distracted by other, more obvious fractures. This patient complained of distal forearm pain but the scaphoid region was not specifically examined. A distal radius fracture and an ulnar styloid fracture were spotted on the x-ray. But, if you look at the very top of the film, you’ll also see a fracture through the scaphoid. Children may not complain of pain exactly over the fracture site, especially when there are fractures elsewhere.

 

Case Resolution

Natasha is seen at ten days post-injury in the fracture clinic. Her splint is removed and whilst the swelling has improved, her range of motion is still restricted by pain and she remains significantly tender in the anatomical snuffbox. She is booked for an MRI of the wrist, which shows a non-displaced fracture line through the distal pole of the scaphoid. She is placed into a scaphoid plaster cast and remains immobilised for a total of six weeks. When the cast is removed, she has no residual symptoms and makes a full, uncomplicated recovery.

 

Selected references

Abbasi D. Scaphoid Fracture. Orthobullets. Website. Available from: https://www.orthobullets.com/hand/6034/scaphoid-fracture[Accessed 20 April 2019]

Dawson-Bowling S, Achan P, Briggs T, Ramachandran M. 2014. Orthopaedic Trauma. The Stanmore and Royal London Guide. CRC Press.

Elhassan B, Shin A. Scaphoid Fracture in Children. Hand Clinics. 2006; 22(1):31-41

Gajdobranski D, Živanović D, Mikov A, et al. Scaphoid Fractures in Children. Srp Arh Celok Lek. 2014; 142(7-8):444-449

Ghane M, Rezaee-Zavareh M, Emami-Meibodi M et al. How Trustworthy Are Clinical Examinations and Plain Radiographs for Diagnosis of Scaphoid Fractures? Trauma Monthly. 2016; 21(5): 1-6

National Institute for Health and Care Excellence (2016) Fractures (non-complex): assessment and management (NICE Guideline 38). Available at: https://www.nice.org.uk/guidance/ng38 [Accessed 12 April 2019]

Jenkins P, Slade K, Huntley J et al. A comparative analysis of the accuracy, diagnostic uncertainty and cost of imaging modalities in suspected scaphoid fractures. Int. J. Care Injured. 2008; 39: 768—774

Pincus S, Weber M, Meakin A. Introducing a Clinical Practice Guideline Using Early CT in the Diagnosis of Scaphoid and Other Fractures. Western Journal of Emergency Medicine. 2009; 4: 227-232(BET 2: Do wrist splints need to have a thumb extension when immobilising suspected scaphoid fractures?Emerg Med J 2011;28:1075-1076.