Carpal Fractures


89
Carpal Fractures


Bert Perey MD FRCSC1, Emanuelle Villemaire‐Côté MD FRCSC2 and Francesc A. Marcano‐Fernández MD PhD3


1University of British Columbia, BC, Canada


2Department of Orthopaedics, CHU de Québec‐Université Laval, Quebec, Canada


3Division of Orthopaedic Surgery, McMaster University, Hamilton, ON, Canada


Clinical scenario



  • A 30‐year‐old laborer fell from his truck and landed on his right upper extremity with the wrist in dorsiflexion.
  • He presents to the Emergency Department with pain and swelling of the right wrist, at the anatomical snuffbox.
  • Range of motion of the wrist is limited by pain. Radiographs are taken and are shown in Figure 89.1.

Top three questions




  1. In patients with a suspected scaphoid fracture but negative findings on initial x‐rays, is magnetic resonance imaging (MRI) more sensitive and cost‐effective than temporary immobilization and repeated x‐rays after two weeks?
  2. In patients with a nondisplaced scaphoid fracture undergoing conservative treatment, does a short arm thumb spica cast achieve higher union rates compared to a below‐elbow casting without thumb?
  3. In patients with a nondisplaced fracture of the scaphoid, does conservative treatment achieve similar union rates to surgical treatment of the scaphoid?

Question 1: In patients with a suspected scaphoid fracture but negative findings on initial x‐rays, is magnetic resonance imaging (MRI) more sensitive and cost‐effective than temporary immobilization and repeated x‐rays after two weeks?


Rationale


A missed scaphoid fracture can have adverse outcomes. It is generally accepted that a delay in diagnosis and treatment of scaphoid fractures can lead to nonunion or malunion resulting in symptomatic osteonecrosis, carpal collapse, or secondary osteoarthritis. This underlines the importance of an accurate and prompt diagnosis.


Clinical comment


Patients presenting with a clinically suspected scaphoid fracture, but negative initial radiographs, are treated with temporary cast immobilization for 10–14 days before a second set of radiographs is performed.


The patient’s radiographs are initially negative. You are planning to immobilize the patient in a cast and reassess him in two weeks with repeat radiographs (Figure 89.2), but you are wondering if an immediate bone scan, computed tomography (CT) scan, or MRI would be more appropriate.

Photos depict PA in ulnar deviation (A), lateral (B), and scaphoid (C) view of the right scaphoid.

Figure 89.1 PA in ulnar deviation (A), lateral (B), and scaphoid (C) view of the right scaphoid.

Photos depict Pronated oblique view of the same patient in Figure 89.1: (A) following the injury, there was a doubt about a waist fracture; (B) 10 days later, radiograph reveals more clearly the waist fracture.

Figure 89.2 Pronated oblique view of the same patient in Figure 89.1: (A) following the injury, there was a doubt about a waist fracture; (B) 10 days later, radiograph reveals more clearly the waist fracture.


Available literature and quality of the evidence


This search produced the following level I studies: a Cochrane meta‐analysis,1 one randomized controlled trial (RCT) comparing the suitability of two imaging techniques (conventional radiography vs a CT scan),2 two RCTs comparing the cost‐effectiveness of MRI versus conventional management,3,4 and two meta‐analyses of mostly prospective cohorts.5,6


Whenever possible, these level I studies will be used to answer the question.


Studies with a lower level of evidence will be used to address the role of other imaging modalities that lack high‐quality evidence.


Findings


Sensitivity and negative predictive value (NPV) of initial and repeated radiographs


The NPV of initial radiographs varies greatly between studies. One large prospective multicenter study of moderate quality showed a sensitivity of 93.7% (95% CI: 0.88–0.96) and a specificity of 100% (95% CI: 0.99–1.00) for patients with clinical suspicion and after five standardized projections.7 A collection of smaller studies shows a range of NPV between 50 and 93% with a mean of 82%.2,3,8–10 To compensate for this variation, patients with clinically suspected acute scaphoid fractures but negative initial x‐rays are typically treated with two weeks of cast immobilization followed by repeated examination and radiographic studies.


A meta‐analysis by Yin et al. demonstrated that radiographs repeated in less than six weeks have a sensitivity of 91% (95% CI: 0.810–0.978) and a specificity of 99% (95% CI: 0.99–1.00).11


Other diagnostic modalities and their utility in avoiding significant, unnecessary immobilization time


Bone scan


The latest Cochrane review reveals that bone scan is sensitive but not specific for diagnosing scaphoid fractures. Sensitivity and specificity of bone scan were 99% (95% CI: 0.69–1.00) and 86% (95% CI: 0.73–0.94).1 Moreover, it requires a delay of at least 72 hours following the injury to capture the osteoblastic activity of the fracture site5 and is also the most invasive test with the need for intravenous radioactive isotopes and a higher dose of radiation compared to CT scan.12


Magnetic resonance imaging


According to the latest Cochrane meta‐analysis, MRI has shown to have a sensitivity of 88% (95% CI: 0.64–0.97) and a specificity of 100% (95% CI: 0.38–1.00) (Figure 89.3).1 Previous meta‐analyses coincide with this high specificity value but grant higher values for sensitivity; 96% (95% CI: 0.91–0.99) and 97% (95% CI: 0.95–0.99).5,11 This decrease in sensitivity value observed in the latest Cochrane meta‐analysis is due to the selection of only high‐ and moderate‐quality studies for this calculation which omitted poor‐quality studies.

Photo depicts Coronal Fat Sat T2 MRI confirming a suspected proximal pole fracture of the scaphoid.

Figure 89.3 Coronal Fat Sat T2 MRI confirming a suspected proximal pole fracture of the scaphoid.


MRI also allows for the ability to detect associated soft tissue injuries.


Computed tomography


CT scan can also identify occult fractures (Figure 89.4) but is more useful in defining the fracture pattern and the angular deformity.13 According to the Cochrane review it has a sensitivity and specificity of 72% (95% CI: 0.36–0.92) and 99% (95% CI: 0.71–1.00), respectively. Similarly to the MRI findings, sensitivity is lower than the one from an earlier meta‐analysis which granted it a sensitivity between 93% (95% CI: 0.83–0.98) and 85% (95% CI: 0.73–0.94).5,11 This reduction in sensitivity is due to the same reasons as the MRI decrease.

Photo depicts CT scan of the same patient in Figure 89.1. CT can identify occult fracture but is more useful in assessing fracture displacement and angulation.

Figure 89.4 CT scan of the same patient in Figure 89.1

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May 14, 2023 | Posted by in Uncategorized | Comments Off on Carpal Fractures

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