Distal placement: tuning fork, preferably in contact with bone
Proximal placement: bell of the stethoscope. If swelling is present then the bell is placed over the area of swelling
If a fracture is present, then the sound heard on the injured side should be absent or significantly reduced compared to the uninjured side.
False positive test (fracture absent but diagnosed as present):
(1) subcutaneous or bleeding at either placement point, which can deaden the sound
(2) incorrect placement of tuning fork or stethoscope
False negative test (fracture present but not diagnosed):
(1) nondisplaced fracture (so that continuity is preserved)
(2) bilateral injuries
(3) tuning fork and stethoscope too close together
Interpretation:
• The test should be used in conjunction with other findings for the evaluation of a trauma patient.
Performance:
• The sensitivity and specificity in various studies vary, with the correct diagnoses made in 81 to 94% of patients, depending on the bone being examined and the patient.
• There are many points where there can be variability in technique. The test should be as standardized as possible.
