Washington University Emergency Medicine Journal Club– April 20th, 2023
You are working a shift in EM-2 one weekend when you encounter Mr. S, a right-handed 38-year old man with no significant past medical history who presents with right wrist pain. He had had a few drinks the previous evening to celebrate his birthday and was in his way to bed when he tripped over a rug and fell forward onto both hands. He has no pain in his left wrist, but describes moderate pain in his right lateral wrist without radiation. He was able to work all day doing manual labor on a construction site, but the pain grew worse as the day progressed.
On examination, he has no deformity, swelling, or ecchymosis. There is mild tenderness over the lateral aspect of the wrist and over the anatomical snuffbox with no pain on axial load of the thumb (How Trustworthy Are Clinical Examinations and Plain Radiographs for Diagnosis of Scaphoid Fractures?). X-rays of the wrist (three views) are negative for acute fracture.
Based on current practice (and UK guidelines) you go to discuss immobilization with the patient given the high risk of an occult fracture, with the plan for repeat imaging in 2 weeks. The patient is concerned about immobilization leading to loss of work and wages, as well as his current lack of insurance leading to an inability to obtain appropriate follow-up. Given these concerns, you discuss with your attending the possibility of obtaining a CT scan to help rule out fracture in a more timely fashion. Your attending cites a previous review from Academic Emergency Medicine‘s Evidence-Based Diagnostics series by a Dr. Carpenter (a name that vaguely rings a bell, but you just can’t place) suggesting that CT cannot rule out fracture. While an MRI is more accurate, it is also more time-consuming and expensive. You wonder if there is additional information that could help this patient potentially avoid unnecessary immobilization without risking long-term functional loss…
Population: Adult patients with traumatic injury involving the wrist, clinical
concern for scaphoid fracture, and negative initial plain radiographs
Intervention: Early computed tomography (CT)
Comparison: Delayed follow-up with repeat plain radiography following a period of
Outcome: Ability to identify fractures of the scaphoid bone missed on initial plain
PubMed was searched using the terms ((CT or “computed tomography”) AND
“scaphoid fracture”), limited to Humans, which resulted in 232 citations. Among
these, 4 relevant articles were identiAied and included for review
Article 1: Pincus S, Weber M, Meakin A, Breadmore R, Mitchell D, Spencer L, Anderson N, Catterson P, Farish S, Cruickshank J. Introducing a Clinical Practice Guideline Using Early CT in the Diagnosis of Scaphoid and Other Fractures. West J Emerg Med. 2009 Nov;10(4):227-32. PMID: 20046238; PMCID: PMC2791722. Answer Key.
Article 2: Ilica AT, Ozyurek S, Kose O, Durusu M. Diagnostic accuracy of multidetector computed tomography for patients with suspected scaphoid fractures and negative radiographic examinations. Jpn J Radiol. 2011 Feb;29(2):98-103. doi: 10.1007/s11604-010-0520-3. Epub 2011 Feb 27. PMID: 21359934. Answer Key.
Article 3: Carpenter CR, Pines JM, Schuur JD, Muir M, Calfee RP, Raja AS. Adult scaphoid fracture. Acad Emerg Med. 2014 Feb;21(2):101-21. doi: 10.1111/acem.12317. PMID: 24673666. Answer Key.
Article 4: Memarsadeghi M, Breitenseher MJ, Schaefer-Prokop C, Weber M, Aldrian S, Gäbler C, Prokop M. Occult scaphoid fractures: comparison of multidetector CT and MR imaging–initial experience. Radiology. 2006 Jul;240(1):169-76. doi: 10.1148/radiol.2401050412. Erratum in: Radiology. 2007 Mar;242(3):950. PMID: 16793977. Answer Key.
Scaphoid fractures can be difAicult to diagnose in the emergency department (ED),
with rates of missed fracture on initial plain radiography ranging from as low as
3.7% when clinic suspicion is low to as high as 27% when suspicion is high (Hauger
2002). On the more extreme end, one study found that among patients with
suspected scaphoid fracture, 69% of those with normal initial x-rays were ultimately
found to have a fracture somewhere in the wrist (Memarsadeghi 2006).
Standard of care in the ED for scaphoid fractures is splinting, although there is some
evidence that a standard Colles’ splint performs as well as the typical thumb spica
(Clay 1991). It is therefore generally recommended that patients with a clinical
suspicion for a scaphoid fracture (consistent mechanism and physical exam
Aindings) and normal radiographs in the ED be placed in a splint with follow-up for
repeat imaging and exam. While difAicult to quantify, there is a non-negligible cost to
routine splinting in these patients, including loss of work, loss of ability to perform
activities of daily living (ADLs), and the cost of follow-up visits and imaging, and
these must be weighed against the potential complications of not splinting a
possible fracture. We therefore sought to assess the viability of performing a CT scan
in the ED for select patients in whom splint placement for follow-up may be more
problematic (e.g. low suspicion for fracture, lack of access to follow-up, lack of
transportation, performance of manual labor).
We Airst reviewed an article from the Evidence-Based Diagnostics series in Academic
Emergency Medicine addressing the diagnostic accuracy of elements of physical
exam and imaging for suspected scaphoid fracture (Carpenter 2014). This
systematic review and meta-analysis found that while no aspect of the physical exam
reliably ruled in or ruled out scaphoid fracture in isolation, the absence (LR- 0.09,
95% CI 0.00 to 11.9) or presence (LR+ = 6.1, 95% CI = 0.04 to 1086) of pain with
resisted supination were most useful in evaluation. Interestingly, plain radiography
at 10-14 days following injury did little to increase (LR+ 4.7, 95% CI 1.6 to 4.4) or
decrease (LR- 0.67, 95% CI 0.50 to 0.89) the likelihood of a fracture when positive or
negative, respectively. CT scan was found to be quite useful in ruling in a fracture
(LR+ 15.4, 95% CI = 8.8 to 27.0) and moderately helpful in ruling out a fracture (LR–
0.23, 95% CI=0.16 to 0.34).
Using methods detailed by Paukir and Kassirer and imputing risks/beneAits of
disease and treatment from the literature, the authors then calculated that patients
with a less than 0.4% probability of a fracture should undergo no additional testing,
while those with a higher probability require additional imaging and examination.
Based on this number, you would need a theoretical patient to have a 7% or lower
pre-test probability of fracture based on clinical suspicion, followed by negative
plain Ailms and a negative CT, to adequately exclude a fracture and not require
further testing. This number, however, is based on several assumptions and limited
by the inability to include the potential costs of immobilization in the calculation.
The diagnostic test characteristics of CT scan calculated in this meta-analysis were
based on 8 individual studies, two of which we reviewed. These two studies
(Memarsadeghi 2006 and Ilica 2011) demonstrated similar abilities to rule out
fracture as that of the pooled result (LR- 0.27, 95% CI 0.10 to 0.72 and LR- 0.14, 95%
CI 0.05 to 0.39, respectively). In the former article, several additional wrist fractures
were identiAied that were not seen on CT, further diminishing the ability to rule out
signiAicant injury. This study seems to be an outlier, however, as 69% of patients with
negative initial x-rays were ultimately found to have a fracture; this is signiAicantly
higher than most other studies on this topic.
A Ainal article was identiAied that was not included in the meta-analysis (Pincus
2009). This prospective, Australian study of 83 patients with negative initial plain
Ailms found that early CT had a sensitivity of 100% (95% CI 93.5% to 100%) and
negative predictive value of 100% (95% CI 93.5% to 100%) for fracture. For those
with a negative study, use of early CT resulted in a mean duration of immobilization
of 2.85 days and mean time off work of 1.6 days.
While these data do not provide deAinitive evidence to guide our management, the
study by Pincus et al suggests that use of early CT with more advanced technology
now available (multidetector 64-slice CT) may be feasible and preferable in certain
clinical situations. Clinicians will have to carefully weigh the risks and beneAits of
missed fracture and prolonged immobilization for those in whom clinical suspicion
for fracture is not high. In particular, this strategy may be useful in at risk
populations for whom follow-up and repeat imaging may not be possible; diagnosis
of a fracture on the initial visit may increase the likelihood of compliance with
immobilization in such patients and make appropriate follow-up easier to arrange.