Temperature changes in serial casting in the treatment of clubfoot

INTRODUCTION: Idiopathic clubfoot (talipes equinovarus) is a congenital deformity of the foot. The common treatment consists of serial manipulation and casting, known as the Ponseti method, which is started in the first week after birth. After an average of five cast changes and often a percutaneous Achilles tenotomy the deformity is corrected [1]. An abduction orthosis is worn for several years to prevent relapse. The application of plaster cast includes soaking the roll in lukewarm water which starts the exothermic curing reaction. After the plaster has cured the surplus water evaporates, which is an endothermic process. Heat is drawn from the surrounding but also from the patient. One case study describes observed hypothermia after the application of a plaster jacket for immobilization of the cervical spine [2]. In a survey among parents (unreported, 49 respondents) a number of parents mentioned that their child seemed to feel cold the first hours after a new cast had been applied. The aim of current study is to investigate the temperature changes underneath the cast in the treatment of clubfoot with the Ponseti method.

METHODS: A 1-wire DS1825 digital thermometer (Maxim Integrated, San Jose, CA, USA) was used to measure the temperature underneath the cast. The sensor was placed underneath the sole of the foot and attached to a custom made data logger which stored time and temperature data every 10 minutes for a full week. Dip duration was calculated as the time from the moment the first maximum was reached until the temperature reached the mean value of the last 6 days. T-Tests were used to test the temperature difference for statistical significance.According to the Medical ethical evaluation committee of the UMCG the study does not fall under the Medical Research Involving Human Subjects act.

RESULTS AND DISCUSSION: Preliminary results of the first seven measurements in four subjects (age 2-30d, all boys, 2 bilateral) are presented in Figure 1. Figure 1: Typical measurement of the temperature underneath the cast during the first 24 hours after casting.After an initial temperature increase after the application of the plaster cast, a decrease was visible in all measurements (p < 0.000). This dip reached a minimum of 23-33°C and lasted 5.9-16h before reaching a relatively stable 34-37°C. During the ISB2017 the additional results of the remaining scheduled measurements will be presented. CONCLUSIONSA considerable decrease in skin temperature was observed after the application of long leg casts in the treatment of clubfoot. Especially in bilateral cases this might cause discomfort or even hypothermia.

ACKNOWLEDGEMENTS: This study has been supported by the Dutch Technology Foundation.