Benjamin Hagan, MS4
The Article: “Pyogenic Flexor Tenosynovitis by Point-of-care Ultrasound in the Emergency
Department.” Hubbard, Daniel, et. al. Clinical Practice and Cases in Emergency Medicine, vol.
2, No. 3, 2018.
The Idea: Flexor tenosynovitis refers to inflammation of a tendon and the potential space
between the inner visceral layer and outer fibrous layer of the tendon sheath. Bacterial infection
is the most common etiology and can lead to serious complications if there is not early diagnosis
and treatment. Kanavel’s signs are the currently recognized standard for diagnosing flexor
tenosynovitis; the signs are as follows: fusiform swelling of the digit, tenderness to palpation of
the tendon, partial flexion of digit, and pain on passive stretch of the tendon. Retrospective
studies, however, have shown that presence of these signs in a patient with a painful swollen
finger are not good at predicting which patients will require surgical debridement and which will
improve with antibiotics alone. The remaining diagnostic uncertainty has led to utilization of
point-of-care ultrasound (POCUS) in diagnosis of pyogenic flexor tenosynovitis. Previous
studies have documented that presence of hypoechoic or anechoic fluid surrounding the flexor
tendon is predictive of purulence at the time of surgical debridement. A normal flexor tendon is
not surrounded by enough synovial fluid to be detected by ultrasound, and so the presence of
fluid on POCUS is therefore potentially useful in diagnosis. This study is the first case series in
the emergency medicine literature aimed to determine if emergency physicians can detect the
finding of fluid surrounding the tendon with POCUS.
The Study: This retrospective case series looked at 7 patients who presented to an urban,
academic emergency department over the course of 8 years and were found to have anechoic or
hypoechoic fluid surrounding the flexor tendon using POCUS. Cases were identified by
reviewing the EMR, and were only included in the study if the consulting hand surgeon made a
final diagnosis of flexor tenosynovitis. The EMR was then reviewed further for information
regarding history of presenting illness, physical exam, specialist consultation, treatment, and
operative reports as well as hospital course and follow-up if available.
The Results: Seven patients were identified who had anechoic or hypoechoic fluid surrounding
the flexor tendon by an emergency medicine physician with POCUS. All patients included in the
study had at least two, and as many as four of Kanavel’s signs on exam. All patients in the study
were male, ranging in age from 16-51 years old. A history of puncture trauma was present in five
of the seven patients. Four of the patients (57%) were managed with surgical debridement, two
(28%) were managed with antibiotics alone, and one (14%) was managed with a bedside I&D.
Both patients managed with antibiotics alone had successful resolution of symptoms and were
without complications at a two-month follow-up. Three of the four patients managed with
surgery had purulence at the time of surgery, and the one patient who did not had received three
days of antibiotics prior to surgery.
The Takeaway: This retrospective study was able to demonstrate that emergency physicians
were able to detect fluid surrounding the tendon of patients diagnosed with flexor tenosynovitis.
The data suggests that fluid on POCUS exam at the time of presentation is useful in the diagnosis
of flexor tenosynovitis, but is not useful in determining which patients will require surgery and
which patients can be managed non operatively. Utilization of ultrasound on initial presentation
may, however, increase the sensitivity of early diagnosis which may lead to more patients being
successfully managed non-operatively. The authors did not report on all cases of flexor
tenosynovitis found in the EMR search criteria, and they did not explain what their exclusion
criteria were, causing concern for selection bias. They do comment on these limitations of the
study and state that prospective studies are needed to better clarify what role POCUS should play
in diagnosis of flexor tenosynovitis. It was also suggested that in future studies there should be
an effort to include findings of tendon diameter and hyperemic flow to potentially increase the
specificity of POCUS for diagnosing pyogenic flexor tenosynovitis.