Sports Medicine Research: In the Lab & In the Field: Ultrasound and Tuning Forks: Another Diagnostic Tool in the Tool Belt for Clinicians? (Sports Med Res)
Friday, October 26, 2012

Ultrasound and Tuning Forks: Another Diagnostic Tool in the Tool Belt for Clinicians?

The Ability of Clinical Tests to Diagnose Stress Fractures: A Systematic Review and Meta-analysis

Schneiders AG, Sullivan SJ, Hendrick PA, Hones BD, McMaster AR, Sugden, BA, Tomlinson C. J Orthop Sports Phys Ther. 2012; 42(9): 760-771

As a clinician, early identification of stress fractures in patients is paramount to establishing a course of action for intervention and treatment. Unfortunately, without immediate access to medical imaging (e.g., magnetic resonance imaging [MRI], radiography, or scintigraphy) we often rely on subjective complaints, location of pain, details from the athlete’s training, medical history, and clinical examination tests despite little evidence to support their diagnostic ability. Schneiders et al performed a systematic review and meta-analysis on the literature involving the diagnostic efficacy of clinical tests for stress fractures. Utilizing eight electronic databases, the authors initially identified 9,321 studies published between January 1950 and June 2011 for possible inclusion. These studies specifically compared clinical tests to radiological imaging of lower extremity stress fractures.  After review of each study’s title, abstract, and full texts (when available); the authors narrowed the pool to nine studies that underwent quality assessment using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. Seven studies investigated therapeutic ultrasound and two studies investigated the use of a tuning fork to identify stress fracture in the lower extremity. MRI and scintigraphy were used as reference imaging to confirm the accuracy of these two clinical tests. The authors found that ultrasound had a pooled sensitivity (correctly identify with a stress fracture) of 64% and specificity (correctly identify absence of a stress fracture) of 63%. These results indicated a low to moderate ability for stress fracture diagnosis. Furthermore, ultrasound had a small positive likelihood ratio (probability of a positive test in someone with a stress fracture divided by the probability of positive test in someone who doesn’t get a stress fracture) of 2.09 and negative likelihood ratio of 0.35. For the two studies that investigated the use of tuning forks, a meta-analysis was not possible so each study was reported individually. Sensitivity/specificity and likelihood ratios presented by these studies were poor. Overall, this review did not support using ultrasound or tuning forks as a stand-alone diagnostic technique for stress fracture identification.

Stress fractures, particularly of the lower extremity, often lead to time-loss from sport or activity. Early intervention means altering activity and reducing physical stress on the lower body. The results of this systematic review and meta-analysis do not support the use of ultrasound and tuning forks for diagnosing stress fractures as standalone tools. Interestingly, Papalada et al found that therapeutic ultrasound may have the potential to assess lower extremity stress fractures. More research may be warranted to determine if there is an optimal ultrasound protocol for evaluating stress fractures. Until we know more, the clinician should rely on sound skills in obtaining a detailed history, patient reports of pain location and intensity, and cautionary use of clinical tests to confirm a decision of referral for physician evaluation and subsequent imaging. Is ultrasound or a tuning fork part of your evaluation currently? What clinical tests do you use to diagnose a stress fracture of the lower extremity?

Written By:  Laura McDonald
Reviewed by:  Jeffrey Driban

Related Posts:
Schneiders AG, Sullivan SJ, Hendrick PA, Hones BD, McMaster AR, Sugden BA, & Tomlinson C (2012). The Ability of Clinical Tests to Diagnose Stress Fractures: A Systematic Review and Meta-analysis. The Journal of orthopaedic and sports physical therapy, 42 (9), 760-71 PMID: 22813530


Anonymous said...

Sensitivity "rules out" and specificity "rules in"

Jeffrey Driban said...

Thanks, the wording in the post has been clarified. A nice description of this can be found at...

"Sensitivity—The proportion of people with the disease who are correctly identified by a positive test result (“true positive rate”)

Specificity—The proportion of people free of the disease who are correctly identified by a negative test result (“true negative rate”)

SnNOut—Mnemonic to indicate that a negative test result (N) of a highly sensitive test (Sn) rules out the diagnosis (Out)

SpPIn—Mnemonic to indicate that a positive test result (P) of a highly specific test (Sp) rules in the diagnosis (In)"

It also provides definitions for other commonly used terms (e.g., positive predictive value).

Anonymous said...

I have used the single leg hop "test" in the past. Pain on the way up with less pain down more indicative of soft tissue injury but pain on landing indicates bony injury.

Laura M. McDonald, PhD, ATC said...

Thanks for the comment!I've also seen anecdotal success with a single leg hop. Seems to mimic the Heel Tap/Bump Test.

Bethany said...

When I suspect a fracture, I often use a tuning fork test as part of my assessment. However, I would never use the tuning fork by itself as a stand alone measure. If a tuning fork test is positive along with other tests (tap/bump, compression, etc) and the mechanism and observations I made all point to the same thing, I will refer the individual for x-rays. For me, I use a tuning fork app on my phone because we do not have one in the athletic training room where I work. It might not have the same results as using a regular tuning fork, but I have found it to be useful. For this app in particular, I have found it to be better at giving true negative tests than true positive tests. This is helpful information to know, even though it is sometimes more useful to know if something is actually broken than actually not broken. Essentially, I like the idea of using a tuning fork, as long as it is in conjunction with other clinical assessments.

Laura M. McDonald, PhD, ATC said...

Thanks for your comment, Bethany. The tuning fork app you mentioned sounds interesting. I imagine it produces a vibration which is used to provoke pain at the suspected site? I agree with you. A tuning fork alone is rarely enough for me to refer for possible imaging.

Chip W. said...

I've always been under the notion that tuning fork and ultrasound are cheap diagnostics, so seeing that the likelihood ratios and sensitivity/specificity are relatively low is a surprise somewhat. As with every tool, using these tools in conjunction with a thorough assessment of history, training and changes in training, location of pain, nutrition habits, menstrual cycles in women, and a single leg hop test are all things I look at with distance runners, as this is the population I work with.

Laura M. McDonald, PhD, ATC said...

Thanks for your comment, Chip. Given your concentrated population of distance runners, how often do you use a tuning fork or ultrasound to aid in diagnosis? For instance, if history, etc. don't provide much evidence that a stress fracture is likely, do you use a tuning fork or ultrasound?

Kale Songy said...

In my limited amount of experience, I think that a tuning fork and ultrasound should only be used to aid in diagnosis if you are feeling unsure. Even then, I don't think that they can rule out or rule in a stress fracture. It is interesting to see research that seems to back this experiential finding up.
I also wonder if this study just used x-ray to diagnose when comparing to Ultrasound and a Tuning Fork? In my experience, there have been times where an x-ray will not show a stress fracture, but an MRI or further diagnostics will.

Laura M. McDonald, PhD, ATC said...

Thanks for your comment, Kale. I think many clinicians favor your viewpoint that these two tools shouldn't be used exclusively to diagnose stress fractures. A combination of symptoms, history, etc. are helpful for me when making that decision.

The review looked at literature that compared tuning fork and ultrasound to MRI and/or scintigraphy results. X-ray films, especially early in a stress fracture progression, can certainly mislead a diagnosis. I have had many physicians use scintigraphy to determine hot spot activity.

Kaitlyn Johnson said...

From what I have learned thus far, I usually start with the compression test and bump test to rule in or out a stress fracture. If those are positive I will usually use a tuning fork. However, I do feel that the compression test and bump test are not always reliable. With working with high school students if you perform these two tests most times the athlete will usually complain of pain. So, figuring out if they have pain from just the injury or an actually stress fracture can be difficulty. When using the tuning fork, if that does come out positive we usually send them out for referral just to double check. I feel that no tests can be 100% reliable. X-ray can be the best bet, but I feel that in the future it would be interesting to see what will come out that will help athletic trainers diagnose a stress fracture more easily.

Marisa Rizzo said...

While reading this article I remembered that I had heard about using ultrasound and tuning forks for stress fractures before. I have never seen anyone use ultrasound for a stress fracture, but i have seen a tuning fork used. The tuning fork did not give a positive to the patient who did end up having a stress fracture. I think it would be very beneficial to athletes and clinicians to have a tool that can detect Stress fractures without having to send the patient out.

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