High-Power Laser Therapy Improves Healing of the Equine Suspensory Branch

There has been much anecdotal support for laser therapy of soft tissue injuries of humans and horses but little hard evidence. Here a well constructed study shows significant improvement in ligament injury of horses. Over the course of the study the healed lesion was about 20% smaller in the treated horses. It may be that such work could be generalized to other soft tissue injuries but will require work to show so. Important to note is the type laser used and the protocol. Also of note is that this did not look at long term soundness and that too will require further work to see if this technique does make horses sounder for longer. Besides the summary below I have included an explanation of types of Lasers used in therapy and the specific protocol used in this study.
DrO

Low-Power vs High-Power
An output power of less than 0.5 Watts is classed as Low Level Laser Therapy LLLT (class III in the USA) whereas lasers with an output powers more than 500 mW or 0.5 Watts are termed High Power Laser Therapy HPLT (Class IV lasers in the USA). HPLT creates heat on the surface of the skin due to their higher power density (irradiance). LLLT is often referred to as “Cold Lasers” since they do not create a heating sensation during treatment.

Laser Protocol
The device used in the current study is a high-power (class 4) multi-frequency laser (Prototype, software installed for the aim of this study, Touch Life Rehab®) with a maximal output of 15W. The laser emits light simultaneously at 4 different wavelengths between 635 and 980 nm. The laser contains a build in temperature sensor to protect the patient against skin burns. In each horse, laser therapy was applied daily on 2 of the 4 induced lesions, on clean skin, starting at day 1 after surgery for 4 consecutive weeks. In each horse, the treatment location was randomly allocated either to the right front and left hind limb, or to the left front and right hind limb, equally divided across the study group. Treatment was performed moving the laser handpiece in a linear fashion upon the lesion area with the handpiece held perpendicular to the skin at a distance of 0.5 cm. Duration of this laser protocol was 20 min.

High-Power Laser Therapy Improves Healing of the Equine Suspensory Branch in a Standardized Lesion Model
Front Vet Sci. 2020 Sep 3;7:600.
Mathilde Pluim 1 2 , Ann Martens 3 , Katrien Vanderperren 4 , René van Weeren 5 , Maarten Oosterlinck 3 , Jeroen Dewulf 6 , Mimoun Kichouh 7 , Bert Van Thielen 7 8 , Marc H W Koene 2 , Antonio Luciani 2 , Lukas Plancke 1 , Cathérine Delesalle 1 5
Affiliations

1 Department of Virology, Parasitology and Immunology, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
2 Tierklinik Lüsche GmbH, Bakum, Germany.
3 Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
4 Department of Veterinary Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
5 Department of Clinical Sciences, Utrecht University, Utrecht, Netherlands.
6 Unit of Veterinary Epidemiology, Department of Obstetrics, Reproduction and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
7 Radiology Department, Brussels University Hospital, Brussels, Belgium.
8 Odisee Hogeschool, Campus Terranova, Training Center for Imaging Technologists, Brussels, Belgium.

Abstract

High-power laser therapy is often used as a treatment for human sport injuries but controlled standardized studies on its efficacy are lacking. The technique has also been introduced in the equine field and recently promising results were reported in a retrospective study focusing on 150 sporthorses suffering from tendinopathy and desmopathy of the SDFT, DDFT, suspensory ligament, and suspensory branches. The goal of the present study was to evaluate the effect of high-power laser in a standardized lesion model in horses. Lesions were created in all lateral suspensory branches of 12 warmblood horses. In each horse, 2 of the 4 lesioned branches were treated daily with a multi-frequency high-power laser for 4 weeks. Color Doppler ultrasonography was performed during and after the treatment period. Six horses were euthanized 4 weeks post-surgery (short-term) and 6 were further rehabilitated until 6 months and then euthanized (long-term). High-field MRI evaluation was performed on all cadaver limbs. On ultrasound, transverse size of the lesion was significantly smaller after 2- and 3 months (p = 0.026 and p = 0.015) in the treated branches. The expected post-surgery enlargement of the lesion circumference and cross-sectional area (CSA) over time, was significantly lower in the short-term laser treated group (p = 0.016 and p = 0.010). Treated lesions showed a significantly increased Doppler signal during treatment (p < 0.001) compared with control. On MRI, in the short and long-term group, the CSA of the lesions was significantly smaller (p = 0.002), and the mean signal significantly lower in the treatment groups (p = 0.006). This standardized controlled study shows that multi-frequency high-power laser therapy significantly improves healing of a suspensory branch ligament lesion.