Assessing Affordance Replaces Subjective-Objective Outcome Measure at the Knee Joint

The importance of including patient-reported outcome (PRO) instruments in evaluating the assessment of clinical outcomes is becoming more widely recognized, with a growing emphasis on the patients' perspective. Clinicians have attempted to link PROs to objective outcomes, resulting in unique data for patient care management. Traditionally, objective and patient-reported outcomes (such as the Knee Injury and Osteoarthritis Outcome Score (KOOS)) have been thought of as two separate constructs that cannot be directly compared.

Can Gibson's affordance theory specify more about objective versus subjective outcomes measurement and unify them? At the knee joint, perceptual systems are active sets of organs operating to reach equilibrium through synergies—the combined action that the skin and the joints are both projected to the somatosensory area of the cortex, to the same area, and the joint cannot even be imagined to deliver a flat map to the brain. Under these assumptions, this study demonstrates how a specific method for assessing knee proprioception could resolve the outcome measure separated by the objective-subjective divide.

The objective of this study is to suggest that the assessment process can be viewed in terms of action possibilities provided by the active sets of organs residing that can obtain and utilize information about the tissue environments in the knee proprioceptive system.