This study examined the sensitivity and specificity of 3 tuning forks to detect stress fractures in trained runners. Radiographs, bone scans, and magnetic resonance images were obtained from 45 runners (mean age, 31.2±13.1 years) presenting with symptoms of stress fractures. Tuning forks of 3 frequencies (128, 256, 512 Hz) were used. Pain was assessed using a scale of 0 (no pain) to 3 (severe pain). Sensitivity and specificity for detecting stress fractures were determined. Higher fork-induced pain ratings were correlated with any positive imaging finding (r = 0.156, P = .056). The odds risk of a positive stress fracture image was 5.91 with a fork-induced pain rating of 3, compared with pain ratings of ≤2. The 256-Hz fork elicited the highest pain ratings and sensitivity for detecting a stress fracture (range, 77.7%–92.3%), and the 512-Hz fork elicited the lowest (range, 50%–76.9%) for all diagnostic tests. Tuning fork-induced pain rating is associated with a positive image finding. A pain rating of 3 is highly predictive of the presence of stress fracture. A 256-Hz tuning fork induced the highest pain ratings and may be the most useful diagnostic frequency.
Dr Wilder is from the Department of Physical Medicine and Rehabilitation, University of Virginia, Charlottesville, Va; Drs Heather Vincent and Kevin Vincent are from the Division of Physical Medicine and Rehabilitation, Department of Orthopaedics and Rehabilitation, UF & Shands Orthopaedics and Sports Medicine Institute, University of Florida, Gainesville, Fla; Dr Stewart is from Norlanco Medical Associates Elizabethtown, and Dr Pack is from the Department of Physical Medicine and Rehabilitation, The University of Pittsburgh, Pittsburgh, Pa.
Address correspondence to Kevin R. Vincent, MD, PhD, Division of Physical Medicine and Rehabilitation, Department of Orthopaedics and Rehabilitation, UF & Shands Orthopaedics and Sports Medicine Institute, University of Florida, PO Box 112727, Gainesville, FL 32610; e-mail: .email@example.com