Imaging the scaphoid problem : a diagnostic strategy for suspected scaphoid fractures
Beeres, F.J.P.
Citation
Beeres, F. J. P. (2008, May 14). Imaging the scaphoid problem : a diagnostic strategy for suspected scaphoid fractures. Retrieved from https://hdl.handle.net/1887/12857
Version: Corrected Publisher’s Version
License: Licence agreement concerning inclusion of doctoral thesis in the Institutional Repository of the University of Leiden
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Chapter
10
Summary
As outlined in chapter 1, the diagnostic and therapeutic management of scaphoid fractures is still surrounded by controversy. A ‘wrong’ or delayed treatment may lead to serious complications. In order to initiate the appropriate treatment as quickly as possible, an accurate diagnostic management of scaphoid fractures is mandatory. Clinical diagnosis remains a great concern for the physician. Bone scintigraphy is the traditional gold standard for suspected scaphoid fractures. Recently, MR imaging has been suggested as the most appropriate investigation in imaging acute scaphoid trauma. There is, however, insufficient evidence for the preferred imaging of acute scaphoid trauma. The diagnostic strategy of suspected scaphoid fracture is, therefore, still surrounded by controversy. To date,
‘Imaging the scaphoid problem’ is therefore an important issue that needs to be addressed.
In chapter 2, the diagnostic value of the function of the wrist and of a number of strength measurements in patients with a suspected scaphoid fracture is described. In a group of 79 patients with a suspected scaphoid fracture a number of clinical tests were performed in the Emergency Department at both the suspected and contra-lateral side. According to a standardised protocol, flexion and extension of the wrist were measured. Supination and pronation strength were calculated, as was the maximal grip strength. All measurements were performed on both the suspected and unsuspected side. According to a standardised algorithm, Magnetic Resonance imaging, bone scintigraphy and clinical follow-up were used to define a final outcome. Scaphoid radiographs missed 17% (13/78) of scaphoid fractures. A haematoma was present in 6 of the 13 patients with a scaphoid fracture and a swollen anatomic snuffbox was found in 10 of the 13 scaphoid fractures.
With 100% sensitivity not to miss a scaphoid fracture, the flexion and extension have a cut off value of respectively 76 and 69% of the contra-lateral side and accordingly 28%
(specificity) of patients can be excluded from a suspected scaphoid fracture. Cut off values for supination strength, pronation strength and grip strength are respectively 34, 40 and 34% of the contra-lateral side and accordingly, respectively 28, 23 and 25%
(specificity) of patients can be excluded from a suspected scaphoid fracture. These results imply for daily practice that if a cut off value of 40% is used no scaphoid fracture will be missed. In addition, if strength measurement is above 40% of the contra-lateral side up to 28% of patients will not have a scaphoid fracture. Consequently, no further investigation is needed and the patient can be functionally treated. If the strength measurement is below the cut off value, a scaphoid fracture can be present and further investigation (such as bone scintigraphy, MR imaging, CT) is required. In conclusion, the presence of a haematoma or swelling of the anatomic snuffbox is not necessarily associated with a scaphoid fracture. Impaired function of the wrist and strength measurements are useful in the diagnostic management of scaphoid fractures as they can exclude up to 28% of patients with a suspected scaphoid fracture. In addition, function of the wrist and strength measurements are of use to decide if further diagnostics are required. Consequently, they improve the diagnostic strategy for suspected scaphoid fractures.
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Chapter 10Summary
The diagnostic value of bone scintigraphy in daily practice for suspected scaphoid fractures is described in chapter 3. In a retrospective study, all patients who attended the Emergency Department over a 24 months period with a suspected scaphoid fracture (tender anatomic snuffbox and pain when applying axial pressure on the thumb) were reviewed. One hundred and eleven consecutive patients with a suspected scaphoid fracture had immediate scaphoid radiographs. Radiographs revealed 55 scaphoid fractures. The remaining 56 patients all underwent delayed bone scintigraphy. Bone scintigraphy showed a fracture in 38/56 patients. The distribution of fractures was:
scaphoid bone 15, distal radius 11, other carpal bones 9 and metacarpal bones 3. In conclusion, if there is a strong clinical suspicion of a scaphoid fracture, which cannot be confirmed by conventional radiology, bone scintigraphy is a valuable diagnostic tool.
The role of bone scintigraphy, however, is not clear if scaphoid radiographs show another fracture. In chapter 4, the group of 111 consecutive patients used in chapter 3 had immediate radiographs and is further analysed. Fifty-five patients had scaphoid fractures only and 6 patients had another fracture but no scaphoid fracture. In 3 of these 6 patients with another fracture, bone scintigraphy revealed 4 occult concomitant fractures: 1 scaphoid, 1 scaphoid and trapezial and 1 capitate fracture. In conclusion, bone scintigraphy is required when scaphoid radiographs do not confirm a suspected scaphoid fracture, even in the presence of another fracture in the carpal region.
Bone scintigraphy proved to deserve a place in the diagnostic management of suspected scaphoid fractures. However, the results require a careful interpretation due to a varying specificity. Chapter 5, therefore, prospectively correlated the results of bone scintigraphy with clinical outcome. In a prospective study, 50 consecutive patients with a scaphoid fracture at physical examination but no evidence of a scaphoid fracture on scaphoid radiographs were analysed. All patients had a protocolised follow-up at fixed intervals.
The clinical outcome was defined according to a standardised algorithm. Bone scintigraphy revealed 32% (16/50) occult scaphoid fractures and 40% (20/50) occult other fractures. Clinical outcome proved that bone scintigraphy was false positive in 5 patients and in 1 case false negative for a scaphoid fracture. Therefore, bone scintigraphy in combination with protocolised physical examination is the gold standard for patients with signs of a scaphoid fracture that cannot be proven on scaphoid radiographs.
In chapter 6, the observer variation of bone scintigraphy in the detection of occult scaphoid fractures in daily practice is illustrated. One hundred subsequent bone scans of patients with a suspected scaphoid fracture but negative initial radiographs were prospectively included to calculate the inter- and intra-observer variation. Three nuclear medicine physicians independently evaluated all bone scans at 2 different points in time with a 3 months interval. The observers filled out a blinded scoring sheet for each patient.
They scored if a scaphoid fracture was present or not. In addition, they scored the presence or absence of another fracture. The inter- and intra-observer variation was analysed using the kappa statistic. The inter-observer variation showed substantial agreement for a scaphoid fracture and almost perfect agreement for another fracture. The intra-observer variation showed almost perfect agreement for both a scaphoid fracture and another fracture. In the present study early static images of bone scintigraphy for suspected scaphoid fractures showed very little inter- and intra-observer variation. In addition, expertise does not seem to have an influence on the results. This enhances the possibility of using bone scintigraphy in daily practice.
The aim of the study described in chapter 7 was to prospectively evaluate the observer variation of Magnetic Resonance (MR) imaging in the detection of suspected scaphoid fractures in daily practice. Seventy-nine consecutive MR scans were included to calculate the inter-observer variation. All patients were suspected of a scaphoid fracture but had no fracture on radiographs. Thirty-eight randomly chosen MR scans were used to calculate the intra-observer variation. Four observers, with varying levels of expertise, blinded scored 3 items; 1) scaphoid fracture, 2) localisation of a scaphoid fracture, and 3) another fracture. The observer variation was analysed using the kappa statistic. The inter-observer variation for a scaphoid fracture had a substantial agreement. Concerning the localisation of a scaphoid fracture and another fracture, there was a moderate and substantial agreement respectively. The intra-observer variation for a scaphoid fracture had an almost perfect agreement. Concerning the localisation of a scaphoid fracture and another fracture, there was an almost perfect and substantial agreement respectively. In conclusion, the observer variation of MR imaging of suspected scaphoid fractures showed a good agreement. But, the influence of expertise with MR imaging in daily practice should not be neglected.
Bone scintigraphy has been widely used as the gold standard in the diagnostic management of occult scaphoid fractures. Currently, MR imaging has been suggested as the most appropriate investigation in imaging acute scaphoid trauma. The value of acute MR imaging in the detection of suspected scaphoid fractures however, has not been evaluated properly. The objective of the study described in chapter 8 was to evaluate if acute MR imaging is superior to bone scintigraphy for suspected scaphoid fractures. One hundred consecutive patients with a suspected scaphoid fracture but no evidence of a scaphoid fracture on scaphoid radiographs were included. All patients had acute MR imaging and delayed bone scintigraphy. They had a standardised follow-up during 6 months after which a final diagnosis was made according to a standardised algorithm. In case of discrepancy between MR imaging and bone scintigraphy, the follow-up was used to define the final outcome. MR imaging showed 16 scaphoid fractures and 24 other fractures. Bone scintigraphy showed 28 scaphoid fractures and 40 other fractures.
According to the final diagnosis there were 20 scaphoid fractures. Concerning a scaphoid
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fracture, MR imaging was false negative in 4 patients and bone scintigraphy false positive in 8 patients. MR imaging had a sensitivity of 80% and specificity of 100%. Bone scintigraphy had a sensitivity of 100% and specificity of 90%. This study could not confirm that acute MR imaging is superior to bone scintigraphy for suspected scaphoid fractures. Therefore, bone scintigraphy should remain the gold standard for suspected scaphoid fractures.
A general discussion is written in chapter 9 and this thesis ends with a summary (English and Dutch) in chapter 10 and chapter 11. The general discussion addresses the implications of this thesis for daily practice, together with some critical remarks and an outline of future perspectives. Finally, a number of conclusions are made.
