Disrupted Tactile Acuity in People With Achilles Tendinopathy: A Preliminary Case-Control Investigation

Study Design Controlled laboratory study, preliminary case-control design. Background The mechanisms that contribute to Achilles tendinopathy remain poorly understood. The disparity between pain experience and peripheral pathology demonstrated in patients with Achilles tendinopathy suggests that changes in central nervous system function may be involved. Objectives To investigate whether lower-limb tactile acuity is impaired in people with nonacute Achilles tendinopathy. Methods Thirteen consecutive participants with nonacute midportion Achilles tendinopathy and 13 healthy controls were enrolled. Two-point discrimination thresholds over the affected Achilles tendon, unaffected tendon, and tendon of healthy controls were evaluated. Independent and dependent t tests were used to compare group means. Results Two-point discrimination distance over the affected limb in participants with Achilles tendinopathy was significantly increased when compared to the unaffected limb (mean difference, 11.7 mm; 95% confidence interval [CI]: 1.9, 21.5; P = .02) and to healthy controls (mean difference, 13.1 mm; 95% CI: 1.6, 24.6; P = .03). There was no significant difference between the healthy controls and the unaffected side in people with Achilles tendinopathy (mean difference, 1.4 mm; 95% CI: -7.9, 5.1; P = .66). Conclusion These data provide the first evidence of reduced 2-point discrimination over the affected tendon in patients with Achilles tendinopathy. Further research is needed to determine the cause for the change in tactile acuity. J Orthop Sports Phys Ther 2016;46(12):1061-1064. Epub 30 Oct 2016. doi:10.2519/jospt.2016.6514.