The proximal suspensory ligament (PSL) is a crucial structure in the equine hindlimb, originating from the proximo-plantar aspect of the third metatarsal bone (cannon bone) and extending distally. It attaches just below the hock joint before bifurcating and inserting into the proximal sesamoid bones¹. The PSL plays a fundamental role in supporting the limb by absorbing and distributing load forces, acting as a damping harmonic oscillator to minimize stress during movement ². Compared to the forelimb suspensory ligament, the hind PSL is more compact and subjected to greater strain due to biomechanical differences ².

Understanding Hind Proximal Suspensory Desmitis (Hind PSD)

Hind proximal suspensory desmitis (PSD) affects the upper third of the suspensory ligament, involving inflammation, strain, or degeneration of its proximal portion. In severe cases, osseous damage may occur near the ligament’s attachment to the bone. Hind PSD can result from repetitive strain, overuse, weakness, or improper conditioning, though acute injuries may also trigger the condition. Poor conformation—such as straight hocks, long toes, or low heels—also increases the risk of hind PSL injuries⁴.

Horses affected by hind PSD often exhibit reduced hindlimb propulsion, poor engagement, and muscle asymmetry. Lameness is frequently subtle or intermittent, typically worsening under saddle or on soft footing⁵.

Prevalence and Impact

PSD is one of the most frequently diagnosed injuries in sport horses, particularly in dressage, show jumping, and eventing disciplines. Hindlimb injuries are more common than forelimb injuries and are often bilateral. Studies estimate that up to 46% of all equine limb injuries involve the suspensory ligament, emphasizing its prevalence.

The economic impact of PSD is significant, as affected horses may require prolonged rest, costly treatments, or early retirement. Conservative management often results in high recurrence rates, with only 13% of cases returning to full athletic performance⁴.

Treatment Approaches

Surgical Intervention: A fasciotomy combined with a neurectomy of the deep branch of the lateral plantar nerve is recommended for chronic cases and has shown improved long-term outcomes⁶.
Biologic Therapies: Injections of platelet-rich plasma (PRP) or stem cells enhance tissue regeneration and healing⁷.
Non-Invasive Therapies: High-intensity laser therapy and extracorporeal shockwave therapy (ESWT) help reduce inflammation, stimulate neovascularization, and promote tissue repair ^8,9.

The Role of Shockwave Therapy (ESWT)

Shockwave therapy (ESWT) has become a preferred treatment for hind PSD due to its non-invasive nature, ability to promote healing, and effectiveness in pain management.

• Cellular Stimulation & Tissue Regeneration: Shockwave therapy works through mechanotransduction, where acoustic waves stimulate cellular responses that promote tissue regeneration and repair. Research shows that ESWT increases transforming growth factor-beta (TGF-β1) expression, a key component in ligament healing and remodeling¹⁰.
• Less Inflammation: ESWT has anti-inflammatory effects, reducing the production of pro-inflammatory cytokines. It also disrupts pain signaling pathways by affecting nerve endings, leading to significant pain relief¹¹.
• Increased Blood Flow: Shockwave therapy stimulates neovascularization, improving blood supply to the injured suspensory ligament, delivering oxygen and nutrients to accelerate healing^10,11.
• Non-Invasive & Convenient: Unlike surgical treatments such as fasciotomy with neurectomy, ESWT is non-invasive, requiring no anesthesia or extended recovery time. It is a quick, well-tolerated procedure that can be easily repeated.
• Proven Effectiveness in Ligament Repair: Studies show positive effects of ESWT on suspensory ligament injuries, with improvements in ligament structure and function documented through ultrasound imaging and clinical assessments⁹.
• Combination with Biologic Therapies for Enhanced Outcomes: ESWT is frequently combined with biologic therapies such as PRP or stem cell injections to further enhance tissue healing, showing promising clinical success in reducing recovery time and improving long-term outcomes.

Conclusion

Hind proximal suspensory desmitis remains a significant concern in equine sports medicine due to its high prevalence and impact on performance. Shockwave therapy has become a go-to treatment for hind PSD because of its proven ability to promote healing, reduce pain, and improve ligament function without invasive procedures. With scientific backing and practical benefits, ESWT is a valuable tool in managing hind proximal suspensory desmitis, helping sport horses recover and return to competition more effectively.

References

1. Dyce, K. M., Sack, W. O., & Wensing, C. J. G. (2006). Textbook of veterinary anatomy. TPB.
2. Chavers, J. C., Allen, A. K., Ahmed, W., Fuglsang-Damgaard, L. H., & Harrison, A. P. (2018). The equine hindlimb proximal suspensory ligament: An assessment of health and function by means of its damping harmonic oscillator properties, measured using an acoustic myography system: A new modality study. Journal of Equine Veterinary Science, 71, 21-26.
3. Skivington, A., Kovac, M., Zakirova, E., Rizvanov, A. A., & Rutland, C. S. (2020). Investigation into Whether Proximal Suspensory Desmitis of the Hindlimb Could Predispose Horses to Sacroiliac Disease. In Equine Science. IntechOpen.
4. Dyson, S. (1994). Proximal suspensory desmitis in the hindlimb: 42 cases. British Veterinary Journal, 150(3), 279-291.
5. Dyson, S. (2006). Diagnosis of proximal suspensory desmitis in the forelimb and hindlimb. In Management of lameness causes in sport horses(pp. 43-51). Wageningen Academic.
6. Dyson, S., & Murray, R. (2012). Management of hindlimb proximal suspensory desmopathy by neurectomy of the deep branch of the lateral plantar nerve and plantar fasciotomy: 155 horses (2003–2008). Equine veterinary journal, 44(3), 361-367.
7. Maleas, G., & Mageed, M. (2021). Effectiveness of platelet-rich plasma and bone marrow aspirate concentrate as treatments for chronic hindlimb proximal suspensory desmopathy. Frontiers in Veterinary Science, 8, 678453.
8. Pluim, M., Martens, A., Vanderperren, K., Sarrazin, S., Koene, M., Luciani, A., ... & Delesalle, C. (2018). Short-and long term follow-up of 150 sports horses diagnosed with tendinopathy or desmopathy by ultrasonographic examination and treated with high-power laser therapy. Research in veterinary science, 119, 232-238.
9. Lischer, C. J., Ringer, S. K., Schnewlin, M., Imboden, I., Fürst, A., Stöckli, M., & Auer, J. (2006). Treatment of chronic proximal suspensory desmitis in horses using focused electrohydraulic shockwave therapy. Schweizer Archiv für Tierheilkunde, 148(10), 561-568.
10. d'Agostino, M. C., Craig, K., Tibalt, E., & Respizzi, S. (2015). Shock wave as biological therapeutic tool: From mechanical stimulation to recovery and healing, through mechanotransduction. International journal of surgery, 24, 147-153.
11. Chen, Y., Lyu, K., Lu, J., Jiang, L., Zhu, B., Liu, X., ... & Li, S. (2022). Biological response of extracorporeal shock wave therapy to tendinopathy in vivo. Frontiers in Veterinary Science, 9, 851894.