Low Level Laser Therapy for the Treatment of Tendinopathy With Emphasis on the Achilles Tendon

Abstract

Low level laser therapy (LLLT) has emerged as a potential treatment option for tendinopathy. Like other electrotherapy modalities, LLLT is a dose dependant modality, thus studies are required to refine dosage guidelines, and to determine effectiveness. Despite evidence from laboratory studies supporting the beneficial effects of LLLT, it still remains on the fringes of mainstream medicine; in particular, positive results obtained in the laboratory have not been consistently reproduced in the clinical setting. The review of the literature undertaken for this thesis highlighted a number of shortcomings in research to date on LLLT: this includes poor methodology, poor reporting of parameters, and varying application techniques. Tendinopathy has become the scourge of the musculoskeletal practitioner because of the nature of the pathogenesis of the condition. Existing literature indicates that tendinopathy is the result of a failure of one of two processes: the healing response, or the normal turnover/remodeling response; however, the definitive solution to the problem remains an enigma. One intervention that is popular, especially for the Achilles tendon (tendo calcaneus) and patellar tendons, is heavy load eccentric exercises. Utilizing methodologies from the top two tiers of the hierarchy of evidence, the thesis investigated the clinical effectiveness of LLLT as an adjunct to an eccentric exercise protocol to treat Achilles tendinopathy. A systematic review with meta-analysis of the literature reporting the use of LLLT to treat tendinopathy was conducted. Twelve studies provided evidence to support the relationship between positive outcomes and current dosage recommendations. Subsequently, a pilot study was conducted using the recommended dose (i.e. 810nm, 100mW applied to six points on the tendon for 30s, for a total of 3J per point and 18J per session) to assess the feasibility of a larger, adequately powered controlled trial. Although the results of the pilot study were not statistically significant, the active treatment group did demonstrate superior change scores for both pain, and function compared to placebo group. Responding to criticism of the parameters used in the pilot study, power density was altered from 2.375W/cm2 to 100mW/cm2 for the main randomised controlled trial (RCT). Although participants in the main trial showed improvements in function scores at 3 months, which were maintained for a further 9 months, there was no difference in change scores between active and placebo groups at any of the follow-up points. These findings provide additional evidence for the effectiveness of heavy load eccentric exercises, but suggest that LLLT treatment, used as an adjunct and at the parameters indicated, provided no additional benefit for participants in the treatment group. This thesis adds to the evidence surrounding the use of laser therapy to treat tendinopathy. The need to refine current guidelines concerning description of parameters and dose has been highlighted by the findings of the pilot and main RCTs. Another important issue raised, relates to exercise adherence and clinical effectiveness of the prescribed dose of eccentric exercise. Finally, the complexity of accurately measuring the effectiveness of physiotherapeutic interventions in the clinical setting has also been highlighted, and presents challenges for the profession in the future.