Morel-Lavallée lesion on the craniomedial aspect of the stifle in a horse: diagnosis, surgical management and outcome.

The research focuses on a new understanding of Morel-Lavallée lesions (MLLs) in horses, a traumatic injury traditionally noted in humans and cats. On a particular case of an 8-year-old Warmblood gelding with non-responsive swelling in the stifle, the authors navigate their diagnostic process and surgical management that eventually led to successful recovery.

Understanding Morel-Lavallée Lesions (MLLs)

• The Morel-Lavallée lesion (MLL) is identified as a post-traumatic degloving injury that occurs when the skin and subcutaneous layers of tissues shift over the deep fascia. This is typically caused by a shearing force during the injury. It further initiates a collection of blood and lymphatic fluid in the space created.
• Traditionally, this condition has been recorded in humans and cats, but there was no known case in horses until the research was performed.

Case of The Warmblood Gelding

• An 8-year old Warmblood gelding, used for dressage, was subjected to the research. It had a large swelling on the craniomedial aspect of its stifle. Despite attempts at conservative treatment, the swelling did not respond.
• The horse was subjected to an ultrasonography, which revealed a large, fluid-filled cavity with a well-defined capsule. Upon further examination, it was found there was a separation between the deep fascia, the muscle of the horse’s hindlimb, and the skin.
• Fluid collected from the horse was tested and yielded a lymphocyte-rich transudate, a type of fluid with low protein concentration often associated with mechanical factors.

Surgical Management

• The horse was put under general anesthesia and a total surgical removal of the capsule was performed.
• A histopathology of the removed capsule pointed out dense fibrovascular tissue with an outer thin layer of adipose connective tissue. This was consistent with an MLL.

Outcome and Conclusion

• Following the surgery, the horse took around nine months to return to its initial athletic level. The cosmetic outcome was deemed excellent.
• The study concluded that chronic MLLs in horses could be effectively treated through total surgical removal of the capsule. It suggested excellent outcomes are possible through this approach.