Reproducibility of pop sensation, Thompson sign in achillotomy, and final Pirani score to predict clubfoot relapse: Achillotomy clinical signs and Pirani predictive ability

Abstract

Ultrasound (US) can guide and confirm percutaneous release of the achilles tendon in the clubfoot. However, this technique may not always be available; therefore, surgeons’ reported feelings of tendon release (“click” or “pop”) and the Thompson sign could demonstrate that they are sensitive and reliable for confirming complete tendon release. The purpose of this study was to compare the reproducibility of clinical maneuvers that aim to detect the reported “click” or “pop” sensation by the surgeon and the Thompson sign after surgical release in percutaneous achilles tenotomy compare with US in patients with clubfoot. A cross-sectional reproducibility study of consecutive patients with idiopathic clubfoot was conducted. All the patients were scheduled to undergo tenotomy in the operating room using the standard percutaneous achilles tenotomy technique under sedation. The surgeon’s reported surgical sensation (“click” or “pop”) and Thompson signs were compared to the US assessment of the cut. The final Pirani score was used to predict recurrence risk and was correlated with the number of plaster casts and age. Forty-five feet were affected in 30 patients. Eighteen (60%) men. Age range: 1 to 60 months. The sensation of “click” or “pop” was recorded in 38 patients, and complete release was confirmed by US in 37 patients, for a sensitivity (Se) of 0.95 and specificity (Sp) of 0.63. Thompson signs were positive in 33 and 36 patients at 2 evaluations, with Se values of 0.87 and 0.92 and Sp values of 0.88 and 0.75, respectively. The Pirani final score, a predictor of recurrence risk, had an area under the curve of 0.80 (95% CI = 0.63–0.97; P = .005), Se = 0.78, and Sp = 0.56, with a cutoff point of 2.75. The feeling of achilles tendon release and Thompson sign had high sensitivity, prevalence, accuracy, and posttest probability. The confirmation of tendon release based on clinical signs could prevent the use of US.