Can tuning forks replace bone scans for identification of tibial stress fractures?

PURPOSE

To compare the performance of the tuning fork test (TFT) with nuclear scintigraphy for the identification of tibial stress fractures.

METHODS

Fifty-two patients with a history and physical examination suggestive of tibial stress fracture underwent a TFT followed by a bone scan. The TFT was performed by applying a 128-Hz tuning fork to the anterior surface of the bared tibia. If the patient reported a marked exacerbation or reproduction of shin pain in a localized area of the tibia, the TFT was considered positive. All patients also underwent a bilateral lower-extremity bone scan.

RESULTS

The sensitivity and specificity of the tuning fork test were 75 and 67%, respectively. The positive and negative predictive values were 77 and 63%, respectively. The positive and negative likelihood ratios with 95% confidence intervals were 2.33 (1.17-4.60) and 0.34 (0.16-0.71), respectively.

CONCLUSION

The tuning fork test is not sensitive enough to rule out a stress fracture on the basis of a negative test. However, in a setting in which there is a moderate to high pretest likelihood of stress fractures, such as military installations with new basic training recruits, it may be reasonable to avoid the cost and delays associated with nuclear imaging by instituting treatment for tibial stress fractures without obtaining a bone scan when the TFT is positive.