Am Fam Physician. 1998;57(2):229-232
to the editor: As budget restraints increase, clinical tools are regaining attractiveness.1 Some years ago, Carter2 published in a letter to the editor a simple clinical method to diagnose bone fractures of the femur and pelvis, based on physical laws of sound transmission. I undertook an investigation to prospectively evaluate the feasibility and validity of the auscultatory technique in 102 consecutive cases of bone fractures.
Bone is a better sound transmitter than muscle or fatty tissue and dampens sound transmission less. To evaluate possible fractures of various tubular bones, the stethoscope is positioned in close proximity to the suspected fracture. Distal to the suspected region, sounds are elicited by tapping a fingernail or fingertip against prominent bony structures, the fingernails or the toenails of the patient. The elicited sounds are then compared with the same procedure on an anatomically comparable region.
After defining the suspected fracture region by means of this test, results were noted on a chart. Then, radiographs were reviewed in order to confirm or falsify the test results.
Of the 102 patients, 91 had fractures localized at one bone, as demonstrated by radiographs. The remaining 11 patients had other alterations, including joint effusions (N=3), lesions of ligaments (N=3), consolidated fractures (N=3), osteomyelitic bone disease (N=1) and pseudarthrosis (N=1). Of the patients with fractures, 80 had single fractures and 11 had multiple fractures. In two patients with wrist involvement, fractures were detected only after repeated radiologic examination, but the auscultation test was negative for the lesions in both cases. The fractures included 19 of the femur, 14 of the radius, 10 of the finger bones and mid-hand, nine of the humerus, six of the tibia or lower leg, five of the ribs, three of the clavicle, three of the mid-foot and two of the elbow, with the remaining fractures at other sites.
Inspection was the only clinical information-gathering modality used besides the auscultation test; palpation or questioning was not permitted. In 24 cases the fracture location was evident from inspection, and it could be suspected in 21 cases. In the other 57 cases, no visible lesion was apparent. Based on these findings, the overall specificity and sensitivity of the auscultation method were calculated (see table) as well as the same values for the 57 cases with nonvisible fractures. Auscultation in cases with nonvisible fractures showed a sensitivity of 89.5 percent and a specificity of 66.6 percent. The auscultation method was even more reliable in diagnosing fractures of the main tubular bones; no false-negative or false-positive diagnoses were made for femur, humerus, radius, tibia or rib fractures.
These findings demonstrate the usefulness of a simple auscultation test in detecting fractures of various tubular bones. Although regarded as the standard, radiology sometimes has limitations,3 as does the auscultation method.4 When the bony (and cartilaginous) continuum is physically broken, e.g. by joint effusion, it is impossible to differentiate fractures from these alterations.