A1 Pulley Tenderness as a Modification to Tenderness along the Flexor Sheath in Diagnosing Pyogenic Flexor Tenosynovitis.

Background: Pyogenic flexor tenosynovitis (PFT) is frequently diagnosed by physical examination according to the Kanavel signs. This study proposes a modification of the Kanavel sign "tenderness over the course of the flexor sheath" by including palpation of the A1 pulley to increase specificity for diagnosis.

Methods: A retrospective review was performed over 8 months for patients in the emergency department who received a consult to hand surgery to rule out PFT. Two cohorts, nonPFT infections and PFT infections, were studied for the presence or absence of the four Kanavel signs, as well as tenderness specifically over the A1 pulley on the affected digit(s) or T1 pulley of the thumb.

Results: There were a total of 33 patients in the two cohorts (21 nonPFT, 12 PFT) with statistically significant differences with regard to the presence of all the Kanavel signs. A1 pulley tenderness had the greatest odds ratio, positive predictive value, specificity, and accuracy when compared with all Kanavel signs. When used in conjunction with each Kanavel sign, there was an increase in specificity in all four signs. Receiver operating characteristic analysis revealed increased area under the curve with A1 pulley tenderness added, indicating improved ability to classify hand infections as PFT versus nonPFT.

Conclusion: Although the classic Kanavel signs have shown reliable clinical utility, this study finds that tenderness at the A1 pulley can be a useful specification of "tenderness over the course of the flexor sheath" to help with the diagnosis of PFT.