Development, construct validity, and reproducibility of a mimetic sealed jar measuring the dynamics of opening.

Measurement of the dynamic kinetics involved in opening a jar may enable health care professionals to understand and train individuals in optimal hand/grip mechanics. This technical note details the design, validity, and reproducibility testing of a mimetic jar capable of measuring the forces and moments and isolated digital forces applied to the lid of the jar. An ecological jar instrument was designed with a torque limiter to provide a natural opening mechanism while a six-axis load cell and force sensing resistors recorded the way individuals applied force to the jar and lid during opening of a sealed container. A total of 115 volunteers participated in a validation of the device and an additional 36 participated in repeatability testing. Compared with prior instruments, this mimetic jar provides more force data and a simulated opening experience - making this jar instrument unique. Future studies utilizing the jar designed herein may allow health care professionals to evaluate patients suffering from debilitating osteoarthritis, fibromyalgia or other neuromuscular conditions and offer improvement strategies.