OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent article in Ultrasound in Medicine and Biology by Bekhet et al., this commentary comes from Christopher Dy, MD, MPH.
In their study from Cairo, Egypt, Bekhet et al. report their experience using ultrasound (US) to examine tendon integrity in the setting of suspected flexor tendon injury. A single musculoskeletal radiologist performed diagnostic US in 35 patients with trauma to the ventral surface of the hand or wrist; a total of 50 tendons were evaluated, with zone-II injuries being the most common.
US correctly identified all complete tendon disruptions, with no false positive or false negative results. US identified partial tendon injuries with 98% accuracy, with 1 false positive result and no false negatives. In comparison, clinical examination alone had a diagnostic accuracy of 88%. The diagnostic performance of US in this study is impressive, and suggests that US may have a role in the diagnostic workup of patients with suspected flexor tendon injury.
While many surgeons still rely on physical examination, it is clear that clinical assessment alone is imperfect. An accurate, objective diagnostic test is desirable for determining the need for (and extent of) surgical treatment as well as in counseling patients. MRI has been suggested to fill this role, but it can be expensive and time-consuming. US is a natural alternative, but its usage in most practice settings (including North America) has been limited because of its operator-dependent nature. That is a key acknowledgment made by the authors of this study, which limits the generalizability and impact of their findings. As only 1 highly specialized radiologist performed the US examinations in the study, it is unclear whether US performed by a less-experienced sonographer would provide the level of detail needed to directly affect clinical management.
Further validation studies (both within the authors’ institution as well as in other centers) would provide important information to determine the utility of US in accurately diagnosing the location and extent of flexor tendon injuries.
In my practice, if there is doubt regarding the integrity of a flexor tendon, I have used US performed by a musculoskeletal (MSK) radiologist or a US-trained physiatrist to provide diagnostic clarity. Admittedly, if the US results do not match my clinical impression, I will either order an MRI or discuss surgical exploration with the patient. This bias in my decision-making process clearly demonstrates my belief that further work is needed to show that US can be used accurately and reliably. While the findings of Bekhet et al. are intriguing, the single-sonographer limitation leads me to question the external validity of their findings. Because of this, the findings of this study are not practice-changing. But I hope to be proven wrong!
Christopher Dy, MD, MPH is a hand and wrist surgeon, an assistant professor of orthopaedic surgery at Washington University School of Medicine in St. Louis, and a member of the JBJS Social Media Advisory Board.
Although an infected finger may not sound like a big deal, the closed-space bacterial infection known as pyogenic flexor tenosynovitis (PFT) has been described as “one of the most devastating infections in the upper extremity.” PFT can rapidly spread from one digit to another, and the incidence of posttreatment complications—including adhesions and tendon tears—has been reported to be as high as 38%.
In a recent issue of JBJS, Qiu et al. report on a mouse model that could help us better understand the pathophysiology of PFT—and more efficiently test established and novel ways of treating it. Previous basic-science investigations into PFT have relied on avian models, but those have proven to be expensive and hard to scale and maintain.
What the Researchers Did:
- Inoculated the tendon sheath of 36 male mouse hind-paws with bioluminescent forms of either Staphylococcus aureus or sterile saline
- Monitored the infected and control cohorts for bioluminescence values and clinical signs such as digit swelling and body-weight reduction
- Performed histological analysis of control and infected paws
What the Researchers Found:
- A significant increase in bioluminescence in the infected group for the first 2 days after infection
- Significantly lower weights in the infected animals compared with controls
- Swelling, scar formation, collapse of the intrasheath space, and thickening of the tendon sheath itself in the infected group
Qiu et al. say this mouse model “could serve as a platform in further understanding the pathophysiology of PFT” and could help evaluate therapies aimed at reducing scarring and stiffness.
Click here to read the JBJS Clinical Summary on Infections of the Hand by Ryan Calfee, MD.