Abstract
Aims: Ankle and foot injuries, especially among teenagers and young adults, are frequently encountered by the primary care physicians. Most common ankle injuries are sprains due to inversion injuries to the lateral ankle ligaments. It has been observed that the overall number of ankle radiographs in the ER is around 15-20%, which includes about 30-40% unnecessary radiographs. Ottawa Ankle Rule (OAR) was first established in 1992, to reduce that unnecessary load on x-ray departments. In light of the current universal practice of evidence-based medicine it is important to undertake verification of the subjective OAR. Bone scintigraphy by merit of its high sensitivity was chosen as the imaging modality of choice to validate the accuracy of OAR.
Methods: The study population comprised of 50 OAR-positive cases and 10 normal controls. Each case was scanned using 3-phase bone scintigraphy (TPBS), following a preliminary radiograph.
Results: Out of 50 OAR-positive cases, x-rays showed frank fractures in only 12 cases, whereas bone scan was positive in 45 cases, out of which 43 had active bone lesions, the remaining 2 had a soft-tissue injury. By considering the TPBS bone scan as the gold standard, we found the sensitivity of OAR was 95% and specificity 61.5% with PPV and NPV at 90% and 80% respectively.
Conclusion We conclude that there is a high concordance between the OAR and the bone scan and that the OAR is evidence-based as determined by the successful verification of the OAR by the TPBS in 95% of the cases. Based on our findings we recommend the routine practice of the OAR in all emergency departments. In patients with acute ankle/foot injuries, with a positive OAR, even with a negative x-ray, the injury should not be taken lightly and if required, a bone scan should be performed for confirmation of lesion. Bone scintigraphy rather than plain radiography appears to be the modality of choice in this situation being cost- and time-effective without compromising the quality of medical care.