Measurement device for ankle joint kinematic and dynamic characterisation

Abstract

The paper describes a measurement device for obtaining the kinematic characterisation and isometric loading of ankle joints under different working conditions. Non-invasive, in vivo experiments can be conducted with this experimental apparatus, the potential of which could be usefully exploited in basic biomedical research, prosthesis design, clinical applications, sports medicine and rehabilitation. The device determines the 3D movement of the foot with respect to the shank and evaluates the torques and moments around the three articular axes in relation to any desired angular position of the ankle complex. When integrated with superficial electromyographic techniques and electrical stimulation, it allows the assessment of the functionality of the lower leg in both mechanical and myo-electrical terms. The paper reports the main mechanical and electronic features of the device (high linearity; maximum moment ranges +/- 300 Nm for flexion-extension, +/- 35 Nm for both pronation-supination and internal-external rotation; angular ranges: +/- 100 degrees of dorsi-plantar flexion, +/- 50 degrees of internal-external rotation and prono-supination; linear ranges: +/- 25 mm along each axis). Results from a healthy volunteer, under voluntary or stimulated conditions, helped in testing its operatability, reliability, robustness, repeatability and effectiveness. Preliminary simplified protocols have been also applied to 20 healthy volunteers, and the main results were 80.8 +/- 11.9 degrees of internalexternal rotation, 46.2 +/- 9.1 degrees of prono-supination and 74.6 +/- 13.1 degrees of flexion-extension. Torques and moments were normalised with respect to a body mass index of 30. The maximum plantar flexion moment (57.5 + 21.3 Nm) was measured with the foot at 150 of dorsal flexion; the maximum dorsal flexion moment (50.2 + 20.3 Nm) was measured with the foot at 150 of plantar flexion.

Mathematical models of passive motion at the human ankle joint by equivalent spatial parallel mechanisms

“…This knowledge would hopefully enhance the current in vivo measurements [11] and the capacity of computer simulation [10] which are necessary to analyse functional conditions and surgical treatments at this joint, in particular the current largely performed total joint replacement and ligament reconstruction. Passive motion was analysed initially because it can reveal potentially the original mutual role of the passive joint structures involved, necessary before any dynamic analysis is performed [28].…”

Effect of selective fatiguing of the shank muscles on single-leg-standing sway

“…Every subject was asked to voluntarily and maximally contract each of the muscles for 5 s, with a rise-time of 1 s approximately, against manual resistance of the appraiser (same, for all the subjects). Testing of each of the specific MVC's was as follows (Giacomozzi et al, 2003): (a) TA, by simultaneously dorsiflexing, internal rotating and supinating the foot; (b) PE, by plantar flexing, external rotating and pronating the foot; (c) GA, by plantar flexing the foot.…”

Lower leg muscle atrophy in ankle osteoarthritis

“…A torque measurement device for the ankle joint was used based on the design of Giacomozzi et al 27 This device measured the isometric torque (Nm) for dorsiflexion and plantar flexion in the neutral position of the ankle (torque transducer: SM-500N; Interface Inc., Scottsdale, AZ). Prior to data collection the linearity and reproducibility of the transducer were tested with known torques of 0 N, 20 Nm, and 40 Nm.…”