An investigation into the effect of number of trials during proprioceptive testing in patients with patellofemoral pain syndrome.

The purpose of this study was to investigate the effect of increasing the number of test trials in the assessment of knee joint position sense, in a group of patellofemoral patients, and second, to investigate the effects of joint angle and type of test. Thirty-two patients with a diagnosis of patellofemoral pain syndrome were admitted to this study. Knee joint position sense was measured by performing an ipsilateral matching activity at target angles of 20 degrees and 60 degrees using two techniques; Passive Angle Reproduction (PAR), and Active Angle Reproduction (AAR). The results show that five repetitions are required for AAR and six for PAR. A two-way repeated-measures ANOVA showed that there was no significant difference (p = 0.559) in the accuracy of angle reproduction for the two angles (60 degrees and 20 degrees ); however, there was a significant difference (p = 0.001) between the two types of test (AAR and PAR). The results of this study have implications for clinicians and researchers who examine knee joint proprioception as part of functional assessment in a variety of knee joint pathologies including PFPS. A "quick" one-off assessment of knee joint position sense may give erroneous data; subjects need to have several trials before a true picture of their proprioceptive status emerges. Type of testing performed, active or passive, is also important, although the angle of testing may not be relevant.