Retrospective study of palmar/plantar annular ligament injury in 71 horses: 2001-2006.

The study, conducted between 2001 and 2006, focuses on the examination and treatment responses of 71 horses suffering from injuries to the Palmar/Plantar Annular Ligament (PAL), a condition not extensively documented in the past.

Research Objectives and Methods

• The main aim of the research was to study the clinical characteristics of PAL injuries, determine their frequency with or without subcutaneous fibrosis (a thickening and scarring process that occurs when too much fibrous connective tissue forms in an area of the body), and/or concurrent injuries within the digital flexor tendon sheath (DFTS), and ascertain treatment responses.
• The study was conducted by selecting horses with clinical markers of PAL injury, and a PAL thickness of at least 2 mm as confirmed by ultrasonography.
• Details about the breed, age, and use of the horse, clinical and ultrasonographic assessments results, and the response to treatment were compiled from case records at three different clinics.
• The treatment methods incorporated either conservative or surgical procedures involving desmotomy of the PAL, i.e., surgical cutting of the ligament, with or without a tenoscopic inspection of the DFTS.
• A telephone survey was implemented to evaluate the response to treatment.

Findings and Conclusions

• General-purpose riding horses in their middle ages or older were mainly part of the study.
• PAL desmopathy, a disorder of ligaments commonly associated with trauma, was more prevalent in hindlimbs than in forelimbs.
• The choice of treatment, PAL thickness, or the presence of subcutaneous fibrosis did not significantly affect the prognosis. Less than half of the horses returned to athletic function.
• There was a slight inclination for horses suffering only from PAL desmopathy to have better outcomes.
• Bilateral thickening of the PAL or concurrent fore- and hindlimb injuries had a negative impact on the prognosis, similar to the concurrent presence of subcutaneous fibrosis and lesions within the DFTS.
• Distortion of the palmar/plantar aspect of the fetlock region with PAL thickening, with or without subcutaneous fibrosis, characterizes PAL injury.
• It is common in older horses for PAL enlargement to occur bilaterally, but it often corresponds with unilateral lameness — the limping or refusal of an animal to bear weight on a limb for the sake of avoiding pain.
• The treatment methods used in this study did not significantly influence the outcome.