Assessment of the suspected fracture of the scaphoid

Abstract

A suspected fracture of the scaphoid remains difficult to manage despite advances in knowledge and imaging methods. Immobilisation and restriction of activities in a young and active patient must be balanced against the risks of nonunion associated with an undiagnosed and undertreated fracture of the scaphoid. The assessment of diagnostic tests for a suspected fracture of the scaphoid must take into account two important factors. First, the prevalence of true fractures among suspected fractures is low, which greatly reduces the probability that a positive test will correspond with a true fracture, as false positives are nearly as common as true positives. This situation is accounted for by Bayesian statistics. Secondly, there is no agreed reference standard for a true fracture, which necessitates the need for an alternative method of calculating diagnostic performance characteristics, based upon a statistical method which identifies clinical factors tending to associate (latent classes) in patients with a high probability of fracture. The most successful diagnostic test to date is MRI, but in low-prevalence situations the positive predictive value of MRI is only 88%, and new data have documented the potential for false positive scans. The best strategy for improving the diagnosis of true fractures among suspected fractures of the scaphoid may well be to develop a clinical prediction rule incorporating a set of demographic and clinical factors which together increase the pre-test probability of a fracture of the scaphoid, in addition to developing increasingly sophisticated radiological tests.

Predictors of fracture following suspected injury to the scaphoid

“…When the pre-test probability of a true fracture is around 40% or greater, supplementary tests such as MRI, CT or bone scan have better diagnostic value and are likely to provide more useful and accurate information. 19,33 Based on our clinical prediction rules, patients with a suspected scaphoid fracture are defined as high-risk if they are male, have sustained a sports injury, have ASB pain on ulnar deviation of the wrist and pain on thumb-index finger pinch at presentation, as well as persistent scaphoid tubercle tenderness at two weeks. We would suggest that these patients would benefit from repeat assessment by a senior member of staff and referral for further imaging if radiographs are negative.…”

“…This fact, combined with the limitations of even the most sophisticated imaging and the lack of a consensus reference standard for a true scaphoid fracture, 19,33 means that the diagnosis of a scaphoid fracture should be considered a probability rather than a certainty. In a previous study of 78 suspected scaphoid fractures, a clinical prediction rule was developed incorporating a previous scaphoid fracture, a reduction in extension of > 50% and a loss of supination strength of ≤ 10% as predictive, 34 but many of the tests performed are not widely used and are difficult to perform in the clinical setting, making the generalisability of the rule doubtful.…”

Cost-Effectiveness of Diagnostic Strategies for Suspected Scaphoid Fractures

“…1 Given the potential for nonunion with a missed fracture, questionable injuries are traditionally managed with initial immobilization for a 2-week period and then reevaluated. This strategy results in unnecessary immobilization for many patients, which leads to productivity loss.…”

Acute Scaphoid Fractures

“…Some studies report that between 30 and 40 % of scaphoid fractures are not identifi ed following initial clinical assessment and scaphoid series radiographs [ 12 ]. Furthermore the inter and intra observer reliability for diagnosis of suspected fracture from scaphoid series x-rays is poor [ 14 , 15 ].…”