Quadriceps Inhibition After Naturally Occurring Patellar Tendon Damage and Pain.

COMPARATIVE studies; CONFIDENCE intervals; STATISTICAL correlation; KNEE; MUSCLE strength; NEUROPHYSIOLOGY; SPINE; STATISTICS; T-test (Statistics); DATA analysis; QUADRICEPS muscle; JUMPER'S knee; NEUROMUSCULAR system; PATELLAR tendon; CROSS-sectional method; SEVERITY of illness index; DATA analysis software; KNEE pain; DESCRIPTIVE statistics; H-reflex; MANN Whitney U Test; KRUSKAL-Wallis Test; ONE-way analysis of variance

Context: After knee-joint injury, pain, effusion, and mechanoreceptor damage alter afferent signaling, which can result in quadriceps inhibition and subsequent weakness. The individual contributions of each factor to inhibition remain unclear due to confounding knee-joint injuries and indirect experimental models. Objective: To characterize the influence of naturally occurring knee damage and pain on quadriceps neuromuscular function in individuals with patellar tendinopathy. Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: Twenty participants who self-reported patellar tendinopathy (PT) and 10 healthy control individuals underwent ultrasonic tendon assessment. Injured participants were dichotomized by an orthopaedic surgeon into groups with (1) pain and structural tendon abnormality and (2) regional pain alone. Main Outcome Measure(s): Quadriceps inhibition was assessed with the Hoffman reflex and the central activation ratio via the superimposed-burst technique. Normally distributed measures were analyzed using a 1-way analysis of variance and post hoc independent t tests. Kruskal-Wallis tests with post hoc Mann-Whitney U tests were used to analyze nonnormally distributed data. An a priori a level of P = .05 was set. Results: Control participants presented with more spinalreflex excitability (0.37 6 0.23) than the PT (0.10 6 0.06; P = .03) and regional-pain (0.18 6 0.05; P = .02) groups. Kneeextension strength was greater in the control (3.37 6 0.59 Nm/ kg) than in the PT (2.41 6 0.67 Nm/kg; P = .01) group but not the regional-pain group (3.05 6 0.66 Nm/kg; P = .24). Control individuals presented with more quadriceps activation (97.93% 6 3.12) than the PT (84.44% 6 16.98; P, .01) and regionalpain (91.17% 6 10.56; P = .01) groups. No differences were present for any measures between the PT and regional-pain groups (P values . .05). Conclusions: Deficits in spinal-reflex excitability, quadriceps activation, and strength were present in both the PT and regional-pain groups. A combination of pain and structural damage appeared to have the greatest negative effect on quadriceps function, as only the PT group presented with neuromuscular outcomes that failed to meet clinical thresholds. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Athletic Training (Allen Press) is the property of KnowledgeWorks Global, Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)