Laser treatment in a model of suspensory ligament branch injury

These results suggest that high-power (class 4, 15 watt) laser therapy enables better lesion healing than conservative treatment. Indeed, in the long-term studies lesion size was 1/3 that of the untreated controls.
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Histological tissue healing following high-power laser treatment in a model of suspensory ligament branch injury
Equine Vet J. 2022 Jan 10.

Authors
Mathilde Pluim 1 2 , Annabelle Heier 3 , Saskia Plomp 4 , Berit Boshuizen 1 , Andrea Gröne 3 , P René van Weeren 4 , Katrien Vanderperren 5 , Ann Martens 6 , Jeroen Dewulf 7 , Ilias Chantziaras 7 , Marc Koene 2 , Antonio Luciani 2 , Maarten Oosterlinck 6 , Leen Van Brantegem 8 , Cathérine Delesalle 1 4
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 Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
4 Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
5 Department of Veterinary Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
6 Department of Surgery and Anesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
7 Unit of Veterinary Epidemiology, Department of Obstetrics, Reproduction and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
8 Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.

Abstract

Background: High-power laser therapy gained popularity recently as a regenerative treatment for tendinitis and desmitis in the horse. However, studies evaluating effects of laser therapy on tissue repair at histological level in large mammals are lacking.

Objectives: To evaluate effects of high-power laser therapy on suspensory desmitis healing, using a model of suspensory ligament branch injury.

Study design: In vivo experiments.

Methods: Standardised lesions were surgically induced in all 4 lateral suspensory branches of twelve healthy Warmblood horses. Laser therapy (class 4, 15W) was applied daily on 2 of 4 induced lesions for 4 consecutive weeks. Horses were randomly assigned to either short-term study (horses were sacrificed after 4 weeks) or long-term study (6 months). Suspensory ligament samples were scored after staining with haematoxylin-eosin and immunostaining for collagen 1- collagen 3- and factor VIII.

Results: In the short-term study, significantly better (lower) scores for variation in density (17% above cut-off score in treated lesions vs. 31% above cut-off score in controls, p=0.03), shape of nuclei (54% vs. 92%, p=0.02), fibre alignment (32% vs. 75%, p=0.003) and fibre structure (38% vs. 71%, p=0.02) were found in laser treated lesions when compared to controls. Collagen 3 expression was significantly higher (32% vs. 19%, p=0.006) in control lesions. In both short- and long-term studies combined, parameters lesion size (44% vs. 56%, p=0.02) and shape of nuclei (53% vs. 84%, p=0.05) scored significantly better in treated lesions. Long-term, significantly better (lower) scores were found in the laser-treated group for lesion size (15% vs. 45%, p=0.008) and a higher percentage above cut-off score for density of the nuclei (27% vs. 9%, p=0.02), compared to controls.

Main limitations: The model of suspensory branch injury is not an exact representation of clinical overstrain lesions.

Conclusions: These results suggest that high-power laser therapy enables better lesion healing than conservative treatment.

Keywords: collagen; fibre; histology; horse; ligament; tendon.