Low-intensity pulsed ultrasound for chronic patellar tendinopathy: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: Patellar tendinopathy (PT) is a common and significant clinical condition for which there are few established interventions. One intervention that is currently being used clinically to manage PT symptoms is the introduction of low-intensity pulsed ultrasound (LIPUS). The aim of this study was to investigate the clinical efficacy of LIPUS in the management of PT symptoms.

METHODS: A randomized, double-blind, placebo-controlled study was conducted. Volunteers with clinically and radiologically confirmed PT were randomly allocated to either an active-LIPUS (treatment) or inactive-LIPUS (placebo) group. LIPUS was self-administered by participants for 20 min/day, 7 days/week for 12 weeks. All participants also completed a daily, standardized eccentric exercise programme based on best practice. Primary outcomes were change in pain during the participant's most aggravating activity in the preceding week, measured on 10 cm visual analogue scales for both usual (VAS-U) and worst (VAS-W) tendon pain.

RESULTS: Out of 156 individuals who volunteered, 37 met the eligibility criteria and were randomized to either active-LIPUS (n = 17) or inactive-LIPUS (n = 20). Using an intention-to-treat analysis, VAS-U and VAS-W for the entire cohort decreased by 1.6 +/- 1.9 cm (P < 0.01) and 2.5 +/- 2.4 cm (P < 0.01), respectively. There were no differences between the active- and inactive-LIPUS groups for change in VAS-U (-0.2 cm; 95% CI, -1.5, 1.1 cm) (P = 0.74) or VAS-W (-0.5 cm; 95% CI, -2.1, 1.1 cm) (P = 0.57). A per-protocol analysis provided similar results.

CONCLUSIONS: These findings suggest that LIPUS does not provide any additional benefit over and above placebo in the management of symptoms associated with PT.