Achilles tendon healing in rats is improved by intermittent mechanical loading during the inflammatory phase.
Eliasson P, Andersson T, Aspenberg P. J Orthop Res. 2011 Aug 1. [Epub ahead of print]
In recent years, the beneficial influence of careful early mobilization (e.g., early weight bearing) on outcomes of Achilles tendon healing has been increasingly appreciated. However, it remains unclear if periodic mechanical loading of the Achilles tendon, has a different effect on the tendon when the loading is applied during different phases of healing (e.g., inflammatory phase, proliferative [repair/regeneration] phase). Eliasson et al. evaluated whether the effects of four episodes of mechanical loading (30 minutes/day of treadmill running for 4 days) resulted in different outcomes when loading was applied during two phases of healing in female rats that had their Achilles tendon surgically cut (the cut tendon was not sutured back together). After surgery, all of the rats were suspended so that their hindlimbs avoided any mechanical loading except when they performed the treadmill exercise. Ten rats were taken down from suspension to perform the treadmill task between 2 and 5 days after surgery (early exercise group; exercise during inflammatory phase) and another 10 rats performed the treadmill task between 5 and 11 days (late exercise group; exercise during proliferative phase). Twenty control rats never performed the treadmill exercise; 10 were evaluated at 8 days (along with the early exercise group) and 10 were evaluated at 14 days (with the late exercise group). Evaluations of all 40 Achilles tendons assessed the mechanical properties of the tendon; which was reflective of tendon healing. Regardless of when the loading was introduced (early or late) the results demonstrated that four episodes of loading increased the mechanical strength of the healing tendon. Overall, the authors concluded that the results suggest that short episodes of early loading may improve the outcome of Achilles tendon healing.
This study is interesting because it provides evidence that careful mechanical loading during the inflammatory phase had positive influences on Achilles tendon healing. It is not clear, however, if these results can be applied to all tendons. Furthermore, the authors noted that it is important to remember that the tendon injuries in this study were clean transverse cuts in healthy Achilles tendons, which are not what are typically experience in clinical practice (typically a ruptured tendon has frayed edges and a history of degeneration). This article provides further support for a recent editorial in the British Journal of Sports Medicine (by Bleakley et al) that proposed it is time to reevaluate one of our most recognized acronyms (PRICE: protection, rest, ice, compression, and elevation). Bleakley et al suggest that we should incorporate a growing body of research that supports implementing safe and effective mechanical loading in acute soft tissue injury management. The authors propose a new acronym: POLICE = protection, optimal loading, ice, compression, and elevation. They suggest that this acronym is not a formula for injury management but instead “a reminder to clinicians to think differently and seek out new and innovative strategies for safe and effective loading…” Furthermore, it is proposed that optimal loading may incorporate manual therapy as well as using walking aids (e.g., crutches) to regulate the amount of loading an injured region experiences. This editorial was not just a call for clinicians to reassess their treatment strategy, but also a call on researchers to vigorously examine the efficacy of acute injury management and how we can optimize acute injury management. What do you think? Should we call on POLICE?
Written by: Jeffrey Driban
Reviewed by: Kyle Harris, Stephen Thomas