Tissue adaptation rate in the treatment of Dupuytren contracture.

STUDY DESIGN: Basic research (cross-sectional). INTRODUCTION: Dupuytren disease can cause disabling contractures of the finger joints. After partial fasciectomy, postoperative hand splinting helps to maintain extension range of motion. PURPOSE OF THE STUDY: To measure how the contraction forces of the finger on the splint change over time. METHODS: Subjects who were treated for Dupuytren contracture with partial fasciectomy were invited to participate in this study. Force sensors were placed in their dorsal extension splint, and the applied force was measured continually for several weeks. RESULTS: Eleven subjects (aged 59-75 years) with the metacarpophalangeal (8) or proximal interphalangeal (3) as their most severely affected finger joint participated. Each night, the measured force consistently decreased to reach a plateau after about 3 hour (adaptation time, 2.55; 95% confidence interval, 0.2-31.8 hours). The time to reach this plateau decreased with time after surgery (≈5%/day, P = .0005, R2 = 0.08). DISCUSSION AND CONCLUSIONS: The observed rate of decrease in the measured force indicates a tissue adaptation time of approximately 3 hours.

Design and Test of a New Inductive Force Sensor.

The currently accepted interval of weekly cast changes in the treatment of clubfeet seems unsubstantiated. A force sensor is needed to determine the adaptation rate of a clubfoot to establish what cast change interval would be most effective and efficient. We developed a force sensor based on the principle that the resonance frequency of an LC-tank changes when a metal target is brought in close proximity. A thin rubber ring between the LC-tank and the metal target transformed this proximity sensor into a force sensor. With a static load test and an incremental load test, the performance of the constructed force sensors was characterized. The custom-made sensor showed excellent sensitivity ((1.7±0.8×105) counts/N), resolution ((0.15±0.06) mN), and accuracy ((3.5±3.0) %) for the application. The observed drift was (2.1±0.7) %/log10(h), which is lower than other thin force sensors. Preliminary results of measurements in the treatment of Dupuytren fingers and clubfeet show good functioning for long-term force measurements.