Relationships between vibratory perception and joint position sense at the knee

Purpose: This study examined relationships between vibrationsensation and joint position sense (JPS) at the knee in healthy subjects; to establish whether vibratory perception threshold (VPT) tests may be used as an alternative to JPS testing and to establish the minimum number of trials required to attain data stability. Relevance: Proprioceptive testing methods at the knee have been criticized for their poor reliability and variability. As both vibration sense and JPS travel through similar neurological pathways, it has been suggested that a relationship exists between JPS and VPT at the knee. Similarities between these methods may open the use of VPT testing as a convenient, cheaper alternative to JPS testing in clinical and research settings. Participants: Twenty healthy adults (11 females, 9 males; aged 26.8±8.2 years) were tested for VPT and JPS. Methods: VPT was tested at five anatomical sites at the lower limb (first metatarsophalangeal joint, medial and lateral malleoli and the medial and lateral femoral condyles) using a biothesiometer (Bio-Medical Instrument, OH). JPS was measured using active angle reproduction (AAR) at target angles of 20◦ and 60◦ of knee flexion using a Cybex Norm Isokinetic Dynamometer System (CSMI Medical Solutions). Analysis: The number of required repetitions were investigated by calculating the cumulative means and standard deviations from VPT and JPS data for all subjects at each test site. The differences between the 5 testing sites for VPT and two test angles for JPS were investigated using repeated measures analysis of variance, followed by post hoc pair-wise comparisons. Pearson product–moment correlation coefficients were used to determine the relationships between the measures of proprioception from VPT and JPS. Results: Results showed no significant correlation between VPT and the two AAR test angles (r < 0.3). Intra-method assessments showed similarities in repeatability, in that VPT (all sites) and AAR 20◦ required 4 repetitions to attain data stability, whereas at AAR 60◦ five repetitions were required. There were significant differences (p < 0.005) between the joints tested for VPT and no significant differences were seen within joint for VPT or between angles for JPS. Conclusions: This study supports the notion that increased numbers of repetitions are necessary for data stabilisation. This study is the first to suggest a minimum reference standard for the number of repetitions required for VPT and JPS testing. It has shown that the JPS test of AAR at 20◦ and all VPT tests required 4 repetitions to attain data stability. However, when testing AAR at 60◦ five repetitions were required to attain data stability. The lack of correlation between VPT and JPS suggests the two modalities measure different facets of proprioception. Some disorders affect one of these sensory functions while partially or completely sparing the other. Further research is required using independent methods in clinical groups such as PFPS to allow proprioceptive subgrouping. Implications: Whilst the two testing modalities are independent of each other, these findings have implications for clinicians and researchers, encouraging the use of broader proprioceptive assessments and increased repetitions to attain consistent stable data