Department of Surgery, Medical Centre Haaglanden, The Hague, the Netherlands 2. Department of Surgery, Gelre Hospitals, Apeldoorn, the Netherlands 3

Transcription

1 Chapter 5 F.J.P. Beeres 1 M. Hogervorst 2 S.J. Rhemrev 1 P. den Hollander 3 G.N. Jukema 4 1 Department of Surgery, Medical Centre Haaglanden, The Hague, the Netherlands 2 Department of Surgery, Gelre Hospitals, Apeldoorn, the Netherlands 3 Department of Orthopaedics, Medical Centre Haaglanden, The Hague, the Netherlands 4 Department of Surgery, VU Medical Centre, Amsterdam, the Netherlands

2 A prospective comparison for suspected scaphoid fractures: Bone scintigraphy versus clinical outcome Based on: A prospective comparison for suspected scaphoid fractures: Bone scintigraphy versus clinical outcome Injury 2007; 38:

3 Abstract Early diagnosis and treatment of scaphoid fractures limits the number of delayed and non-unions. Bone scintigraphy proved to be a sensitive diagnostic tool for the detection of occult scaphoid fractures. However, the results have to be interpreted with care. The objective of the present study was to compare the results of bone scintigraphy with clinical outcome. 48 Methods: In a prospective study, we analysed 50 consecutive patients with signs of a scaphoid fracture at physical examination but no evidence of a scaphoid fracture on scaphoid radiographs. All patients had a protocolised follow-up at fixed intervals. The clinical outcome was defined according to a standardised algorithm. Results: 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. Conclusion: 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.

4 Materials and methods During a period of 18 months, we prospectively analysed 50 consecutive patients who visited the Emergency Department with an acute trauma and a suspected scaphoid fracture after physical examination (see below) but no evidence of a scaphoid fracture on scaphoid radiographs. All had a tender anatomic snuffbox and pain when applying axial pressure (first or second digit). Patients with a scaphoid or other fracture in the carpal region, including either carpal, metacarpal, radial and ulnar fractures on 1 of the scaphoid radiographs, were excluded. Polytrauma patients and those younger than 18 years old were also excluded. A bone scintigraphy was performed after 3 days. The diagnostic protocol used for clinically suspected scaphoid fractures is shown in Figure 5.1. Suspected scaphoid fracture Scaphoid radiographs No scaphoid fracture Scaphoid cast Bone scintigraphy (> 72h.) Scaphoid fracture Treatment Chapter 5 Bone scintigraphy versus clinical outcome 49 Weeks after No fracture Other fracture Scaphoid fracture injury 2 P.E. P.E. P.E. 4 P.E. 6 P.E. P.E. P.E. 8 P.E. 10 P.E. 12 P.E. 24 P.E. P.E.: Physical Examination Figure 5.1 Flowchart of prospective protocol.

5 Physical examination In the Emergency Department and at fixed intervals throughout follow-up (Figure 5.1) patients had a physical examination, which consisted of the following. Patients were asked to localise the punctum maximum for pain. When proceeding, the physician examined both wrist and hand. Pressure was applied on the anatomic snuffbox, distal radius and other carpal bones. Next, axial pressure was applied on both the first and second digit. Finally, flexion and extension of the wrist were measured. All physical examinations were performed blind to the results of previous physical examinations, bone scintigraphy and scaphoid radiographs. 50 Management Patients with no evidence of a fracture in any of the tests were treated functionally with a support dressing. Patients with a scaphoid fracture were treated with a scaphoid forearm cast for 6 weeks. However, when there was still clinical evidence of a scaphoid fracture after 6 weeks, a new cast was applied for an additional 2 weeks after which a physical examination (as described above) was performed. This procedure was repeated every 2 weeks (for a maximum of 12 weeks of immobilisation) until there were no longer clinical signs of a fractured scaphoid. If another fracture in the carpal region (including carpal, metacarpal, distal radial and ulnar fractures) was present, patients were treated according to the local protocol. Clinical outcome All patients had physical examinations at fixed intervals, as shown in Figure 5.1. Prior to all physical examinations, the cast was removed. Clinical outcome was assessed, based on the physical examination blinded to the results of bone scintigraphy. At the end of follow-up the following algorithm was used to define the clinical outcome. If bone scintigraphy showed: No fracture, with a normal physical examination at 2 or 6 weeks, bone scintigraphy was considered correct. However, if there were clinical signs of a fracture after 2 and / or 6 weeks, bone scintigraphy was considered false negative; Another fracture in the carpal region and physical examination after 2 weeks (during change of cast) matched with such a fracture, bone scintigraphy was considered correct. But, when physical examination after 2 weeks showed no signs of fracture, bone scintigraphy was considered false positive; A scaphoid fracture, confirmed on physical examination after 2 weeks (during change of cast), bone scintigraphy was considered correct. If however, neither physical examination after 2 weeks, nor consecutive physical examinations showed evidence of a scaphoid fracture, there was no scaphoid fracture. Bone scintigraphy was then considered false positive. The algorithm used to decide if a bone scintigraphy is correct or false is shown in Table 5.1.

6 Table 5.1 Algorithm used to decide if a bone scintigraphy is correct or false. Bone scintigraphy diagnosis Clinical outcome Bone scintigraphy No fracture No fracture Correct Fracture False negative Other fracture Fracture Correct No fracture False positive Scaphoid fracture Fracture Correct No fracture False positive Table 5.2 Results of bone scintigraphy of 50 patients with a suspected scaphoid fracture but no evidence of a fracture on scaphoid radiographs. Fracture Frequency Percent Scaphoid Scaphoid and distal radius 2 4 Other None Total Results Chapter 5 Bone scintigraphy versus clinical outcome 51 All 50 patients were older than 18 years and gave their informed consent. The study included 29 men and 21 women of mean age 42 (range 18-72) years. There were no bi-lateral injuries. All but 1 were clinically examined within 24 hours after trauma with the 1 patient reviewed within 36 hours. The results of bone scintigraphy of these patients are shown in Table 5.2. In 16/50 patients there was a scaphoid fracture, 2 of whom had a scaphoid and a distal radius fracture. In addition, there were 20 patients with another fracture in the carpal region. In only 14/50 patients there was no fracture on bone scintigraphy. The results of physical examination, in relation to the outcome of bone scintigraphy, are shown in Table 5.3. Three of the 14 patients with a scaphoid fracture on bone scintigraphy had neither clinical signs of a fracture 2 weeks after injury nor at any of the subsequent revisions. In addition, 1 patient had a physical examination matching with another carpal fracture instead of a scaphoid fracture at both 2 and 6 weeks after injury. The remaining 10 patients all had clinical signs of a scaphoid fracture after 2 weeks. For 3 patients the

7 Table 5.3 Results of physical examination and bone scintigraphy of 50 patients with a suspected scaphoid fracture but no evidence of a fracture on scaphoid radiographs. P.E. fractures Scaphoid Scaphoid Other None Total B.S. and distal B.S. fractures radius Scaphoid Scaphoid and distal radius Other None Total P.E P.E.: Physical examination; B.S.: Bone scintigraphy period of immobilisation was extended to respectively 8, 10 and 12 weeks. All patients, including the 3 in which the period of immobilisation was extended, were free of complaints at 3 and 6 months after injury. One of the 2 patients, with a scaphoid and distal radial fracture on bone scintigraphy, only had clinical signs of a scaphoid fracture after 2 weeks. The other patient had clinical signs of a distal radial fracture, but no scaphoid fracture. In the 20 patients with another fracture in the carpal region, physical examination matched with a fracture in 15 patients. However, in the remaining 5 patients there were no clinical signs of a fracture 2 weeks after injury. Of the 14 patients with no fracture on bone scintigraphy, only 1 had a scaphoid fracture as a clinical outcome. This patient had remaining clinical signs of a scaphoid fracture 2 and 6 weeks after injury. After 8 and 12 weeks there were no more clinical signs of a scaphoid fracture. Finally, all 50 patients were free of any complaints and had good function of both hand and wrist after 6 months, so, none of the patients developed a non-union. Discussion Bone scintigraphy revealed 32% (16/50) occult scaphoid fractures. Two of whom also had an occult distal radius fracture. These results even exceed the number of occult fractures in our initial study. 4 In addition, there were 40% (20/50) occult other fractures in the carpal region. Four different observers initially reviewed all scaphoid radiographs before bone scintigraphy. Therefore, it is very likely that these fractures would have been missed due

8 to the limitations of plain scaphoid radiographs and not due to observer factors. Out of the 16 patients with a scaphoid fracture on bone scintigraphy, clinical outcome did not match with bone scintigraphy in 5 patients. Two of these 5, however, had signs of another fracture but no scaphoid fracture on clinical examination. Concerning other fractures in the carpal region, clinical outcome was not in agreement with bone scintigraphy in 5 patients (out of the 20) and they were therefore considered as false positive. In conclusion, bone scintigraphy was false positive in 5 patients and false negative in 1 for a scaphoid fracture. Concerning scaphoid fractures, bone scintigraphy has a sensitivity of 92% (11/12) and a specificity of 87% (33/38). Until now there was inadequate proof in the literature concerning the specificity of bone scintigraphy. As physical examination has a sensitivity of 100%, the specificity of 87% of bone scintigraphy for scaphoid fractures is reliable. 29 In addition, a specificity of 87% is compatible with the literature, which reports a specificity between 60 and 95% for bone scintigraphy for scaphoid fractures. 5,7,10,12 Nonetheless, there were still 30% (15/50) occult other fractures in the carpal region that had been missed on scaphoid radiographs. This study protocol, however, was designed to evaluate the role of bone scintigraphy in the detection of occult scaphoid fractures. Accordingly, physical examination focused on scaphoid fractures. Therefore, our physical examination consisting of sequential diagnostic tests is a useful tool in the assessment of scaphoid injuries. If there was a positive bone scintigraphy for a scaphoid fracture but negative physical examination after 2 weeks, we continued immobilisation for the remaining 4 weeks. Only if after 6 weeks there were still no signs of a scaphoid fracture, did we believe that there was no scaphoid fracture. Future studies could investigate whether immobilisation could be stopped after 2 weeks. Chapter 5 Bone scintigraphy versus clinical outcome 53 Recent data have demonstrated a high sensitivity and specificity for both MR imaging and CT. 12-3,18-9,22 In addition, there are articles favouring MR imaging over bone scintigraphy. 12,17 On the other hand, authors have concluded that MR imaging is not superior to bone scintigraphy. 9 Although the results of MR imaging and CT are promising, no study has prospectively compared the value of acute MR imaging and / or CT with bone scintigraphy in daily practice. Therefore, bone scintigraphy is, even today, often recommended as the diagnostic modality of choice to confirm or rule out an occult scaphoid fracture. This prospective study was designed to evaluate the diagnostic value of bone scintigraphy. We compared the findings of bone scintigraphy with clinical outcome in patients with a suspected scaphoid fracture that cannot be proven on scaphoid radiographs. Sequential physical examination confirmed that bone scintigraphy is a sophisticated tool in the detection of occult scaphoid fractures. Returning to our hypothesis, we can state that the

9 sensitivity is 92% and specificity 87% for bone scintigraphy concerning scaphoid fractures. So, the diagnostic yield for scaphoid fractures was even higher and the number of occult other fractures found even greater. 54 Physical examination increases the diagnostic value of bone scintigraphy, especially by filtering out patients with a false positive bone scintigraphy. Therefore, we advise, that for patients with a clinically suspected scaphoid fracture and normal scaphoid radiographs, bone scintigraphy should be mandatory. In addition, there is a call for routine physical examination. Bone scintigraphy in combination with physical examination is the gold standard to which any new diagnostic modality has to compete.

10 Chapter 5 Bone scintigraphy versus clinical outcome 55