You can try the Joint Position Sense (JPS) test and the Treshold To Detection of Passive Motion (TTDPM) test. It is customary to do these tests in a isokinetic dynamometer, so if you dont have one of these it may be difficult to get reliable results
There are some simple things to try e.g. standing on one foot with eyes open and then eyes closed and note the change in sway - not sure how this can be quantified without a forceplate. Then there is the "wobble board" a number of brands available with varying degrees of sophistication which would allow quantification.
Berg's balance scale and Tinitti's POMA are the two tests for balance that can be done on healthy old adults. use CPM instead of isokinetic machines for knee proprioception. these tests are reliable one for your query.
The JPS and TTDPM tests are done in an isokinetic machine, but the patient is passive and do not exert any force. The speed and direction of the movement arm is controlled by the dynamometer, and the patient passively follows the arm-movements (i.e CPM)
Many thanks for you replies, we have access to a Cybex isokinetic dynamometer. Using the CPM approach, with Berg's balance test, seems most appropriate as I have experience with both. However, if you have any further suggestions, do let me know.
I suggest to take into account the unconscious component of proprioception and consequently a quantitative measure of single stance stability in different sensory conditions. Considering the subjects of your investigation you could find some useful concepts in this two articles:
Article Single Stance Stability and Proprioceptive Control in Older ...
Article Proprioceptive Training and Injury Prevention in a Professio...
James, keep in mind that at this moment we still struggle to identify if proprioception can actually be measured directly and in fact what proprioception really is.
Article Overcoming the Myth of Proprioceptive Training