Contracture diagnosis system using wearable tactile sensor

Contracture is diagnosed by doctors or physical therapists through palpation on slidability of patient’s joints. However, the diagnosis depends on tactile perception of each therapist and subjective. Quantifying contracture palpation can increase diagnosis accuracy and improve its efficiency. This paper proposes a contracture diagnosis system with a wearable skin vibration sensor. The sensor is worn on the finger pad of the therapist, allowing the therapist to touch patient’s joint for the contracture palpation with his/her bare fingertip. The sensor detects frictional vibration induced by sliding disturbance of the soft tissue around the joint when the patient’s arm or leg is moved. The system comprises the sensor, an audio interface, and a PC. The sensor output based on the frictional vibration is intermittent pulse waveform, and mean pulse density in the sensor output during the palpation is proposed for the evaluation. Experimental results on knee, shoulder and waist by a well-trained physical therapist show that the obtained pulse density has a good relation with subjective ratings and is consistent with the transition of the friction vibration according to increasing the repeated number of the palpation. These results indicate the availability and validity of the sensor system.