[Occult fractures of the wrist joint: high resolution image magnification roentgen versus MRI]

Computed tomography versus magnetic resonance imaging versus bone scintigraphy for clinically suspected scaphoid fractures in patients with negative plain radiographs

BACKGROUND

In clinically suspected scaphoid fractures, early diagnosis reduces the risk of non-union and minimises loss in productivity resulting from unnecessary cast immobilisation. Since initial radiographs do not exclude the possibility of a fracture, additional imaging is needed. Computed tomography (CT), magnetic resonance imaging (MRI) and bone scintigraphy (BS) are widely used to establish a definitive diagnosis, but there is uncertainty about the most appropriate method.

OBJECTIVES

The primary aim of this study is to identify the most suitable diagnostic imaging strategy for identifying clinically suspected fractures of the scaphoid bone in patients with normal radiographs. Therefore we looked at the diagnostic performance characteristics of the most used imaging modalities for this purpose: computed tomography, magnetic resonance imaging and bone scintigraphy.

SEARCH METHODS

In July 2012, we searched the Cochrane Register of Diagnostic Test Accuracy Studies, MEDLINE, EMBASE, the Database of Abstracts of Reviews of Effects, the Cochrane Central Register of Controlled Trials, the NHS Economic Evaluation Database. In September 2012, we searched MEDION, ARIF, Current Controlled Trials, the World Health Organization (WHO) International Clinical Trials Registry Platform, conference proceedings and reference lists of all articles.

SELECTION CRITERIA

We included all prospective or retrospective studies involving a consecutive series of patients of all ages that evaluated the accuracy of BS, CT or MRI, or any combination of these, for diagnosing suspected scaphoid fractures. We considered the use of one or two index tests or six-week follow-up radiographs as adequate reference standards.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts and assessed full-text reports of potentially eligible studies. The same authors extracted data from full-text reports and assessed methodological quality using the QUADAS checklist. For each index test, estimates of sensitivity and specificity from each study were plotted in ROC space; and forest plots were constructed for visual examination of variation in test accuracy. We performed meta-analyses using the HSROC model to produce summary estimates of sensitivity and specificity.

MAIN RESULTS

We included 11 studies that looked at diagnostic accuracy of one or two index tests: four studies (277 suspected fractures) looked at CT, five studies (221 suspected fractures) looked at MRI and six studies (543 suspected fractures) looked at BS. Four of the studies made direct comparisons: two studies compared CT and MRI, one study compared CT and BS, and one study compared MRI and BS. Overall, the studies were of moderate to good quality, but relevant clinical information during evaluation of CT, MRI or BS was mostly unclear or unavailable.As few studies made direct comparisons between tests with the same participants, our results are based on data from indirect comparisons, which means that these results are more susceptible to bias due to confounding. Nonetheless, the direct comparisons showed similar patterns of differences in sensitivity and specificity as for the pooled indirect comparisons.Summary sensitivity and specificity of CT were 0.72 (95% confidence interval (CI) 0.36 to 0.92) and 0.99 (95% CI 0.71 to 1.00); for MRI, these were 0.88 (95% CI 0.64 to 0.97) and 1.00 (95% CI 0.38 to 1.00); for BS, these were 0.99 (95% CI 0.69 to 1.00) and 0.86 (95% CI 0.73 to 0.94). Indirect comparisons suggest that diagnostic accuracy of BS was significantly higher than CT and MRI; and CT and MRI have comparable diagnostic accuracy. The low prevalence of a true fracture among suspected fractures (median = 20%) means the lower specificity for BS is problematic. For example, in a cohort of 1000 patients, 112 will be over-treated when BS is used for diagnosis. If CT is used, only 8 will receive unnecessary treatment. In terms of missed fractures, BS will miss 2 fractures and CT will miss 56 fractures.

AUTHORS' CONCLUSIONS

Although quality of the included studies is moderate to good, findings are based on only 11 studies and the confidence intervals for the summary estimates are wide for all three tests. Well-designed direct comparison studies including CT, MRI and BS could give valuable additional information.Bone scintigraphy is statistically the best diagnostic modality to establish a definitive diagnosis in clinically suspected fractures when radiographs appear normal. However, physicians must keep in mind that BS is more invasive than the other modalities, with safety issues due to level of radiation exposure, as well as diagnostic delay of at least 72 hours. The number of overtreated patients is substantially lower with CT and MRI.Prior to performing comparative studies, there is a need to raise the initially detected prevalence of true fractures in order to reduce the effect of the relatively low specificity in daily practice. This can be achieved by improving clinical evaluation and initial radiographical assessment.

[The diagnosis of recent scaphoid fractures: review of the literature]

Fractures of the scaphoid are the most common carpal fractures. A review of the literature indicates that the prevalence of the fracture in the case of clinical suspicion is less than 50%. A quality X-ray examination remains essential as an initial diagnostic tool in the evaluation of scaphoid fractures. Its sensitivity varies from 59 to 79%. Patients with negative X-rays present with about 18.7% of scaphoid fractures; 5% of bruised scaphoid; 13% of radius fractures and 7% of miscellaneous bone lesions. If not treated promptly, a scaphoid fracture may be compounded by non-union with associated risk factors such as avascular necrosis and osteoarthritis. Considering these risks, patients with suspected scaphoid fracture with normal X-rays, routinely undergo wrist immobilization until imaging confirms or denies the presence of fracture. Consequently, more than half of the patients undergo wrist immobilization needlessly. This may have a negative impact on their professional life and personal activities while representing a high medical cost. MRI is the imaging technique of choice for suspicious or negatice X-rays. MDCT is less costly than MRI or bone scan, readily available and highly effective for trauma patients but is lacks accuracy and should be used with caution in this indication.

Carpal fractures excluding the scaphoid

Although carpal fractures other than of the scaphoid are uncommon, vigilance in diagnosing these potentially serious fractures is paramount to early and effective treatment. Physical examination and standard plain radiographs may reveal only subtle findings. Use of special radiographic views and computed tomography may help elucidate the diagnosis. Treatment is particular to each fracture. Nondisplaced fractures should be treated nonoperatively. For intra-articular carpal bone fractures, virtually any amount of displacement is unacceptable and requires reduction and fixation. This article organizes current knowledge of these potentially difficult fractures, with a table of diagnosis and treatment guidelines.

Apport de la radioscintigraphie quantitative dans les traumatismes du poignet avec radiographies initiales normales

PURPOSE OF THE STUDY

Fractures of the scaphoid must be diagnosed quickly to avoid persistent nonunion and the risk of osteoarthritis. Despite meticulous physical examination and adequate x-ray detection, numerous occult fractures still go unrecognized. The aim of this prospective study was to analyze the pertinence of quantitative radio-scintigraphy (QRS) presently used for the diagnosis of occult wrist fractures.

MATERIAL AND METHODS

Quantitative radio-scintigraphy (QRS) is a new imaging technique associating quantitative bone scan and numerical fusion between bone scan images and x-ray images. We conducted a prospective study between November 1994 and March 1999 to evaluate the pertinence of this examination technique for the diagnosis of occult wrist fractures in patients presenting clinical symptoms suggestive of wrist fracture but whose plain x-rays were initially considered normal. Further some patients had several series of plain x-rays performed at several week intervals in order to search for fractures becoming progressively visible on plain x-rays. After the QRS data was acquired, these patients' x-rays were reviewed again. We also compared the cost of QRS, repeated x-rays, bone scan and MRI at the Besançon University Hospital.

RESULTS

QRS was performed in all 154 patients and revealed 61 fractures (56 single-line and 5 multiple-line fractures). Thus 43.5% of these patients had occult wrist fractures (41% of which involved the carpal scaphoid).

DISCUSSION

Occult fracture of the wrist, particularly the carpal scaphoid, is frequent. Repeated x-ray examination does not increase the rate of detection of these fractures. Bone scans may also fail to reveal occult fractures. MRI is a key examination in the assessment of wrist fracture symptoms, but is presently not available in all institutions. Bone scan is classically insufficiently precise. QRS is a rapidly available low-cost examination which we have found to be indispensable for the diagnosis of occult wrist fractures. With early QRS diagnosis, the risk of neglected carpal scaphoid fracture and subsequent nonunion and osteoarthritis together with the personal, social, and medicolegal consequences can be avoided.

[Imaging diagnostics of ulnar wrist pain]

An exact knowledge of the value of different pictorial diagnostic techniques allows a focussed and rapid diagnosis of ulnar wrist pain. A prerequisite for the choice of the best possible method of investigation is an exact clinical examination. The basic examination involves conventional recording at both the centralised at the symptomatic levels. If there is a suspicion of occult bone lesion, finely focused, magnified graphics, CT or bone scintigraphy should be used, depending on both the problem faced and availability. For tissue or ligament lesions, stress graphics, movement studies or MRT, also with contrast media, should be used. Bone scintigraphy is a suitable method to differentiate between inflammatory tissue and/or bone changes.

Occult fractures of the waist of the scaphoid: early diagnosis by high-spatial-resolution sonography

OBJECTIVE

This study evaluated the diagnostic accuracy of high-spatial-resolution sonography in the diagnosis of occult fractures of the waist of the scaphoid.

SUBJECTS AND METHODS

Sonography of the scaphoid bone with a 12-MHz transducer was performed in 54 patients with clinically suspected scaphoid fracture and normal findings on initial radiographs, including specific scaphoid images. Three levels of clinical suspicion were considered: high (20%), moderate (30%), and low (50%). Attention was paid to the continuity of the scaphoid cortex and to the surrounding soft tissues (i.e., hemarthrosis or hematoma). Data from early sonograms were then compared with the results of radiography repeated 10-14 days after the initial trauma. In cases of persistent suspicion despite normal findings on follow-up radiographs, the presence of fracture was evaluated on CT (four patients), MR imaging (one patient), or bone scanning (one patient).

RESULTS

Follow-up examinations proved fracture of the scaphoid waist in five patients. In all patients, diagnosis of fracture was suspected on initial sonograms showing cortical disruption associated with soft-tissue abnormalities. There was one false-positive finding and no false-negative results. Using cortical disruption as a diagnostic criterion, we found the sensitivity, specificity, and accuracy of high-resolution sonography for the depiction of scaphoid fracture to be 100%, 98%, and 98%, respectively. Using soft-tissue abnormalities alone as a criterion, we found the sensitivity, specificity, and accuracy of high-resolution sonography to be 100%, 65%, and 68%, respectively. The overall prevalence of occult fracture was 9%, ranging from 3.7% for low suspicion to 27% for high suspicion of fracture.

CONCLUSION

High-resolution sonography is a reliable and accurate method of evaluating occult fractures of the scaphoid waist. Cortical disruption is the diagnostic key. Soft-tissue abnormalities alone lack specificity.