The effect of focused extracorporeal shock wave therapy on collagen matrix and gene expression in normal tendons and ligaments.
Authors: Bosch G, de Mos M, van Binsbergen R, van Schie H T M, van de Lest C H A, van Weeren P R
Journal: Equine veterinary journal
Summary
# Extracorporeal Shock Wave Therapy: Understanding the Biological Cost and Benefit Extracorporeal shock wave therapy (ESWT) enjoys widespread clinical use in equine practice despite limited mechanistic understanding of how it actually affects tendon and ligament tissue. Bosch and colleagues investigated this knowledge gap by applying focused ESWT to healthy tendons and ligaments in six sound Shetland ponies—treating the suspensory ligament origin, superficial digital flexor tendon, and common digital extensor tendon at two time points (3 hours and 6 weeks prior to tissue harvest)—then analysing treated tissue against untreated contralateral controls using histology, real-time PCR, and biochemical assays. The findings paint a more complex picture than assumed: ESWT caused immediate collagen fibre disorganisation visible histologically at 3 hours post-treatment with residual disruption at 6 weeks; degraded collagen initially increased significantly at 3 hours (P=0.012) before normalising by week 6 (P=0.039); crucially, genes encoding type I collagen (COL1) and matrix metalloproteinase-14 (MMP14) were upregulated 6 weeks after treatment, suggesting an active repair response. The clinical implications are nuanced: applying ESWT to structurally normal tissue deliberately induces matrix damage and should therefore be avoided or approached conservatively, with restricted exercise in the immediate post-treatment period; conversely, this controlled tissue disruption may intentionally trigger healing pathways in chronic tendinopathies, though practitioners must weigh the short-term tissue trauma against potential longer-term regenerative benefits and ensure treatment is reserved for pathological cases rather than routine application.
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Practical Takeaways
- •ESWT should not be used on normal, healthy tendons and ligaments due to unnecessary tissue damage and collagen disorganisation
- •If ESWT is applied, restrict exercise for several weeks post-treatment as matrix disruption persists for at least 6 weeks
- •The induced tissue disorganisation may have therapeutic value in chronic tendinopathies by triggering repair mechanisms, but this requires further evidence in pathological tissue
Key Findings
- •ESWT caused disorganisation of normal collagen structure visible at 3 hours post-treatment with remnants persisting at 6 weeks
- •Degraded collagen levels increased at 3 hours (P=0.012) but decreased by 6 weeks post-ESWT (P=0.039)
- •COL1 (P=0.004) and MMP14 (P=0.020) gene expression were upregulated at 6 weeks, suggesting a repair response
- •Treatment of normal, non-injured tendinous tissue results in measurable matrix disruption and requires careful clinical consideration