Keywords
carpus - scaphoid - fracture - pediatric - MRI
Carpal injuries in children present a clinical challenge due to their non-specific
clinical features, partial ossification of the carpus, and often occult radiological
findings on plain radiography. While blunt wrist trauma is common, carpal injuries
in children are not. Timely interventions are important to avoid missed injuries and
complications, such as non-union or avascular necrosis from scaphoid fractures.[1] For children without bony or ligamentous injuries, it is beneficial to minimize
unnecessary immobilization and multiple hospital attendances. Diagnosis and treatment
should take into account the progressive ossification of the pediatric carpus and
its inherent diagnostic challenge. There is a scarcity of evidence-based guidance
for the management of symptomatic wrist following acute trauma in the pediatric population.
In recognition of this, our pediatric hand and upper limb service in a tertiary Children's
Hospital developed a management algorithm to standardize treatment. We hypothesized
that early magnetic resonance imaging (MRI) will identify those with bony or ligamentous
injuries, allowing prompt stratification between immobilization and early therapy.[2]
[3] For those with distal pole fracture of the scaphoid, we hypothesized that this cohort
requires a shorter duration of immobilization than those with a waist or proximal
pole fracture.[4]
[5]
The purpose of this study was to assess the injury pattern and clinical outcomes of
the under-16-year-olds treated with suspected acute post-traumatic wrist injuries
in accordance with the unit's algorithm. A secondary aim was to evaluate the patient
care pathways and adherence to, and limitations of, the proposed algorithm.
Methods
This is a prospective case series of children and adolescence under the age of 16
years treated in our institution for acute post-traumatic suspected carpal injuries
over a period of 26 months. Chronic injuries or those with uncertain date of injury
were excluded. All children were initially assessed by the local Pediatric Accident
& Emergency Department (A&E), with plain film radiography, and were referred to the
pediatric hand and upper limb trauma clinic with splintage, cast immobilization or
advice for hand elevation as appropriate. We followed our unit's management protocol/algorithm
([Fig. 1]). Patient care journeys were recorded prospectively, which include patient's symptoms,
investigations, and treatment prescribed at each clinic attendance. Injury pattern,
clinical outcome, and patient care pathway were assessed. Adherence to the algorithm
was analyzed retrospectively and deviations were recorded. Descriptive analyses and
statistics were conducted, with exclusion of cases lost to follow-up. Bone and soft
tissue injury diagnoses were taken from formal radiological reports of plain film
radiography and MRI scans, although treatment may be initiated acutely from clinician
interpretations of imaging findings.
Fig. 1 (A) Management algorithm for acute post-traumatic suspected carpal injuries (under 16
years).[1]
[2]
[3]
[6]
[7]
[8]
[9]
[10]
[11] (B) *Management of symptomatic undisplaced carpal fractures confirmed on MRI. MRI, magnetic
resonance imaging.
Results
Demographics
A total of 151 cases (95 boys) were treated during the study period over 26 months.
Three cases were lost to follow-up and were excluded. The mean age was 12 years (range
of 7–15 years). Twenty-two percent of the cases (n = 33) were 10 years or under. The majority (72%) had occult bony injury with radiological
evidence on MRI. There was a strong male predominance in those with carpal bone injuries,
which shifted to an almost equal gender distribution in those 10 years or under ([Table 1]).
Table 1
Demographics and radiological findings in accordance with age
|
|
10 y or less
|
11–15 y
|
Total
|
|
No. of cases
|
|
33
|
118
|
151
|
|
Gender
|
Male
|
16
|
79
|
95
|
|
Female
|
17
|
39
|
56
|
|
M:F
|
1:1.1
|
2:1
|
1.7:1
|
|
MRI findings
|
Fracture only
|
28 (85%)
|
76 (65%)
|
104 (69%)
|
|
Fracture + soft tissue injury
|
0 (0%)
|
4 (3.5%)
|
4 (2.5%)
|
|
Soft tissue injury only
|
0 (0%)
|
2 (1.5%)
|
2 (1.5%)
|
|
No injury
|
4 (12%)
|
31 (26%)
|
35 (23%)
|
|
Not performed
|
1 (3%)
|
5 (4%)
|
6 (4%)
|
|
Plain film imaging “suspicious” = positive
|
Sensitivity
|
39.3%
|
43.9%
|
42.7%
|
|
Specificity
|
100%
|
67.7%
|
71.4%
|
|
Scaphoid fractures
|
Number of cases (%)
|
25 (76%)
|
65 (55%)
|
90 (60%)
|
|
Distal pole
|
17
|
33
|
50
|
|
Waist
|
7
|
22
|
29
|
|
Proximal pole
|
0
|
1
|
1
|
|
Distal pole + waist
|
1
|
9
|
10
|
|
Ratio (distal pole: waist)
|
2.4:1
|
1.5:1
|
1.7:1
|
|
>1 Fracture
|
Number of cases (%)
|
7 (21%)
|
24 (20%)
|
31 (21%)
|
Impact of Early MRI
MRI was performed in all but six cases (4%). This revealed bony and/or soft tissue
injuries in the majority of patients (74%), while the remaining quarter had no injuries
identified on MRI permitting early mobilization, reassurance, and discharge ([Fig. 2]).
Fig. 2 MRI findings. MRI, magnetic resonance imaging.
Using MRI as the “gold standard,” the sensitivity and specificity of plain film radiography
in this study were 42.7 and 71.4%, respectively ([Table 1]). Despite no obvious bony injury on initial plain radiography, 72% had evidence
of occult bony injury on MRI, highlighting the value of early use of MRI ([Fig. 3]). There was a single case where a fracture diagnosed on plain film was subsequently
discounted based on unremarkable MRI findings.
Fig. 3 Distribution of plain radiography and subsequent MRI findings. MRI, magnetic resonance
imaging.
The presence of pain, swelling, and reduced range of motion (ROM) was not reliably
predictive of carpal injuries. Only 21 patients described all three features on initial
assessment, of which 33% did not have bony or ligamentous injury on MRI.
Distal Pole Scaphoid Fracture
The scaphoid was the most commonly involved carpal bone, with 90 fractures out of
108 patients with carpal bone injury on MRI ([Table 2]). Distal pole fractures were more common than fracture of the waist, and there was
one case of proximal pole fracture in an 11-year-old boy ([Table 1]). All acute fractures were minimally displaced and managed in accordance with the
unit's protocol/algorithm ([Fig. 1B]) and achieved union without surgical fixation. Undisplaced fracture of the distal
pole of the scaphoid in patients over 10 years old was treated with a shorter period
of immobilization (4 weeks) with no adverse impact on outcome.
Table 2
Fracture pattern in accordance with age
|
10 y or less
|
11–15 y
|
Total
|
|
Scaphoid
|
25
|
65
|
90
|
|
Capitate
|
6
|
9
|
15
|
|
Trapezium
|
1
|
10
|
11
|
|
Distal radius
|
2
|
5
|
7
|
|
Triquetrum
|
2
|
5
|
7
|
|
Lunate
|
0
|
6
|
6
|
|
Metacarpal
|
0
|
5
|
5
|
|
Hamate
|
0
|
3
|
3
|
|
Trapezoid
|
1
|
2
|
3
|
|
Pisiform
|
1
|
2
|
3
|
|
Distal ulna
|
0
|
2
|
2
|
Injury Pattern and Clinical Outcome
MRI revealed concomitant injury of more than one carpal bone in one-fifth of cases
and this was consistent across the ages ([Table 1]). Following the scaphoid, the next most commonly affected carpal bones were the
capitate and trapezium ([Table 2]).
The injury pattern of those requiring prolonged follow-up included fractures of the
scaphoid waist, fractures of more than one carpal bone, and soft tissue injuries ([Fig. 4]). Soft tissue injuries identified on MRI constituted a small number of cases (4%),
which included two ganglions and one case each of scapho-trapezium-trapezoid ligament
disruption, scapho-lunate ligament disruption, triangular-fibro-cartilage complex
injury, and soft tissue edema only. A bone cyst in the triquetrum was identified as
an incidental finding and was not included as bony injury from trauma.
Fig. 4 Injury patterns and out-patient follow-up requirements.
The greater sensitivity of MRI also detected bone injuries of lesser severity described
radiologically as “bone bruise,” contusion or edema (n = 19). This often involved scaphoid fractures in combination with bone bruise of
the carpus, and were managed as bony injury in accordance with the unit's protocol/algorithm
([Fig. 1A, B]).
Adherence and Limitations
The core statistics of the cohort's treatment pathway is presented in [Fig. 5]. Prompt hand clinic referral following injury, early use of MRI and diagnoses and
standardized management protocol allowed safe stratification of patients, minimizing
number of hospital visits and follow-up duration. Patients on average attended three
hand clinic visits, excluding initial A&E assessment, with a mean follow-up of 5.5
weeks and an immobilization period of 5.1 weeks. Almost four out of five patients
(79%) had three clinic visits or less.
Fig. 5 Treatment pathway core statistics.
Cast or splint immobilization applied from A&E (88% of cases) was included within
the total immobilization period, limiting excess period of treatment. In patients
with radiologically confirmed carpal fractures ([Fig. 6A–C]), the mean duration of treatment was 6.0 weeks, with three (3.2) clinic attendances,
compared with 4.0 weeks and three (2.7) clinic attendances for those without bony
or ligamentous injuries.
Fig. 6 (A–C). X-ray and MRI of scaphoid fracture: 14-year-old girl, left wrist, high velocity
trauma. (A) X-ray PA view: no fracture reported (lunate cyst coincidental finding). (B) MRI (T2_tse_fs_cor) and (C) (T1_tirm_sag): undisplaced fracture distal pole of scaphoid, marrow edema within
the body of the scaphoid. Nonspecific marrow edema noted within the lunate, in addition
to an incidental cyst. MRI, magnetic resonance imaging.
Variation from the management protocol/algorithm predominantly surrounds an extended
follow-up timeframe following MRI from 1 to 2 weeks, accounting for 65% of cases.
Compliance with the protocol/algorithm improved from 13 to 78% excluding this most
common cause of variation. Other deviations from the algorithm included discharge
without General Hand Clinic follow-up for scaphoid waist fractures, prolonged cast
immobilization of distal pole fractures beyond the recommended 4 weeks and the use
of removable splints, such as the Futura, instead of full cast immobilization.
Discussion
Radiological Imaging
In the 2015 Cochrane review, bone scans were found to have the highest sensitivity
(100%), specificity (98%), and a positive predictive value of 85 to 93% at 72 hours.[12] Their drawbacks include the increased radiation exposure, diagnostic delay of at
least 72 hours, and invasiveness.[9] In comparison, computed tomography (CT) carries a sensitivity of 85.2% and specificity
of 99.5%, and MRI sensitivity of 97.7%, specificity of 99.8% and a negative predictive
value of 100%.[9] Despite reduced sensitivity and added radiation exposure compared with MRI, CT may
be more appropriate in cases necessitating detailed delineation of fracture fragments,
and in some units, they are more readily available and economical.[2]
Multiple studies in the literature assessed the yield of varying imaging modality
in suspected pediatric scaphoid and other carpal injuries. Interpretation of plain
radiographs can be challenging due to incomplete ossification of carpal bones and
physeal lines.[7] Conventional approach based on repeated plain radiography and subsequent CT or MRI
when symptomatic is likely to confer additional hospital attendances, diagnostic uncertainty
and parent and child anxiety. In this study, 58% had an initial unremarkable X-ray
and 25% had a suspicious fracture on plain film as occult fractures later were identified
on MRI scan. In a series of 56 patients, 75% of those with confirmed scaphoid fracture
on MRI reported negative initial X-rays.[9] In another series, 74 fractures were identified in 64 patients in 90 MRIs performed
for radially symptomatic wrists.[2] MRI was found to have greater interobserver reliability.[2]
[3] Due to the variable ossifications of carpal bones and the relative greater chondral
components in younger patients and reduced radiation exposure, the use of MRI was
deemed more suitable in our series than other imaging modalities such as CT. The availability
of various imaging modalities and the turnover time for reporting vary between institutions,
especially in an emergency setting. In this study, based on a tertiary referral center,
prior arrangement with the radiology department supported a policy of performing and
reporting of MRI for carpal trauma within 7 to 10 days. We recommend working in partnership
with the radiology department in designing a management algorithm that takes into
consideration the local demographics, trauma caseload, and available resources. Where
MRI availability is limited, it is reasonable to perform plain film radiography and
immobilization for suspected carpal trauma, with early MRI at 2 weeks for those with
persistent symptoms.
The diagnostic challenges posed by non-specific signs and symptoms and occult radiological
findings of the injured wrist are well recognized. Volar tenderness, radial deviation
pain, and pain with active ROM were identified as predictors of scaphoid fractures
in those with negative initial radiographs.[8] However, examination of a painful wrist in a child or adolescent may be challenging,
and the positive predictive value of clinical scaphoid tenderness in children aged
4 to 11 years is low.[13] In one study, 31 out of 104 (30%) patients with suspected scaphoid fracture and
an initial unremarkable plain film had subsequent radiological confirmation of fracture
on follow-up.[8] This figure was 63 out of 91 (72%) patients in our study.
Scaphoid Fractures
Historically, scaphoid fractures in adolescence were thought to be more common in
the distal pole, with a male preponderance, as reflected in our cohort.[4]
[9] This may be due to the distal to proximal direction of ossification pattern of the
scaphoid.[14] It is worth noting that waist fractures were more common, resembling an adult fracture
pattern.[14]
[15] Higher BMI and high-energy trauma, including sport injuries, were thought to be
contributory factors and account for such adult-type injury patterns.[14] Distinction between fractures of the distal pole and that of the waist or proximal
pole was incorporated into our unit's management algorithm based on literature findings
of a quicker rate of healing in the former. Undisplaced fracture of the distal pole
of the scaphoid, in the majority, heals without complications after 4 to 6 weeks of
cast immobilization.[5] In a review of 56 patients with scaphoid fractures, aged 13 years or under, all
but one case united without complication.[4] An average of 4 weeks immobilization was required for distal pole fractures versus
4.9 weeks for waist fractures.[4]
Concomitant Injuries
The high incidence of concomitant injuries was another key finding of this study.
This finding is related to the high sensitivity of MRI and the standardized usage
within our unit's algorithm. While associated injuries alongside pediatric scaphoid
fractures are uncommon, recent studies suggest they are not rare.[5] Some reports present 15 and 21% incidence of associated injuries.[2]
[14] In our study, 27 out of 90 pediatric scaphoid fractures (30%) had associated injuries.
The three most common carpal fractures, in descending order of frequency, were the
scaphoid, capitate, and trapezium.
10 Years or Under
Pediatric scaphoid fractures are clustered within the 11 to 15-year group, and are
rare in those under 9 years of age.[9]
[16] In this study, a greater female distribution was observed in those aged 11 years
or younger. This contrasted with a strong male majority for the full cohort of under
16. More advanced skeletal maturity may account for this. The appearance of the scaphoid
ossification nucleus (4–5 years vs. 5–6 years) and the completion of endochondral
ossification (13 vs. 15 years) both occur at a younger age in females compared with
males.[9]
Management Algorithm
Our study demonstrated that the cohort of patients without bony or ligamentous injury
received a shorter duration of immobilization and fewer hospital appointments. There
were 34 cases that presented with a symptomatic wrist which were subsequently shown
to have no abnormality on MRI. Of these patients, half remained symptomatic at their
second visit, and the reassuring findings on MRI may have facilitated earlier return
to mobilization and full recovery. MRI has a strong negative predictive value.[3]
Limitations
There are inherent biases within a cohort observational study like ours, where our
algorithm was set up based on the literature, but not proven prior to the study period.
We admit that it is difficult to plan clinical trials due to the relative low incidence
of pediatric carpal injuries. Hence, we focused on capturing patients with a symptomatic
post-traumatic wrist via A&E referral to our regional pediatric hand and upper limb
clinic. Some A&E departments within our catchment area have follow-up facilities,
and it is reasonable to believe that a proportion of patients would have been managed
solely in A&E.
There are further unknowns making our algorithm difficult to fully judge. The optimal
imaging modality of the injured pediatric carpus is not known. The clinical relevance
of occult carpal fractures identified on MRI, but not seen on CT is not determined.
The advantages of limiting radiation exposure and greater sensitivity, compared with
CT, may lead to additional immobilization in cases otherwise not detected on X-ray
or CT. Therefore, the choice between MRI and CT in the management of the symptomatic
pediatric wrist remains nuanced.
Summary
Pediatric carpal injuries are uncommon, and clinical examination findings correlate
poorly with radiological diagnoses. The use of a departmental management algorithm
allowed for standardized care and in our unit, has shown good results with low complication
rate and favorable fewer hospital appointments. Our results support routine use of
MRI scan for the identification or exclusion of occult carpal injuries in the pediatric
population. We also noted a shorter duration of immobilization in fracture of the
distal pole of the scaphoid at 4 weeks.
