The triple compression stress test for diagnosis of tarsal tunnel syndrome

Abstract

The diagnosis of tarsal tunnel syndrome (TTS) lacks objectivity and consistency. A new test was designed, called triple compression stress test (TCST), to elicit stress on posterior tibial nerve and its branches, in an attempt to provoke signs of its entrapment. In this test, the ankle is placed in full planter flexion and the foot in inversion, with even, constant digital pressure applied over the posterior tibial nerve. Basic clinical examination to fifty patients with symptoms suggestive of TTS in one or both feet was done. Forty healthy volunteers (80 feet) were enrolled as a control group in the study. We then performed our designed clinical TCST, as well as, basic conventional electrodiagnostic studies bilaterally on all patients and controls. Consecutively, electrodiagnostic TCST was done for patients with negative basic nerve conduction results. The clinical TCST was positive in 61 out of 65 (93.8%) symptomatic feet. It provoked symptoms in 6 new asymptomatic feet. The electrodiagnostic TCST was positive in 78 feet, of which 67 had a positive clinical test and 11 had false negative clinical test. Both tests were negative in all the control feet. Clinical TCST sensitivity was 85.9% while specificity was 100%. TCST achieved a simple, fast and very reliable provocative maneuver to increase the sensitivity of TTS diagnosis both clinically and electrophysiologically.