Tenoscopically guided proximal digital annular ligament desmotomy for the treatment of proximal digital annular ligament desmitis.

Overview

• This study developed and evaluated a tenoscopically guided surgical technique to treat proximal digital annular ligament (PDAL) desmitis in horses.
• The technique was tested on cadaver limbs and applied in clinical cases, showing promising outcomes despite some technical challenges.

Background

• The proximal digital annular ligament (PDAL) is a band of connective tissue around the horse’s digital flexor tendons.
• Desmitis refers to inflammation and damage of a ligament, in this case the PDAL, causing lameness and reduced performance in horses.
• Traditional surgical treatments for PDAL desmitis involve desmotomy, which means cutting the ligament to relieve pressure.
• Tenoscopy is a minimally invasive technique using a small camera inside the tendon sheath to guide precise ligament cutting.

Objectives

• To describe and evaluate a tenoscopically guided technique for performing desmotomy of the PDAL in horses.
• To assess the completeness of the ligament transection and look for any surgical damage in cadaver limbs.
• To report clinical outcomes of horses with PDAL desmitis treated using this technique.

Methods

• Ex vivo testing:
  • Ten normal equine hindlimbs from cadavers were used to practice and investigate the procedure.
  • Access to the digital flexor tendon sheath (DFTS) was obtained via a lateral basisesamoid portal.
  • A palmar/plantar annular ligament (PAL) desmotomy was performed first to improve maneuverability.
  • Additional portals were created proximolaterally and distally in the midline to facilitate cutting different parts of the PDAL under tenoscopic visualization.
  • The limbs were then dissected to examine if the PDAL had been completely transected and to check for unintended damage, particularly to nearby tendons like the superficial digital flexor tendon (SDFT).
• Clinical evaluation:
  • Five clinical cases of horses diagnosed with PDAL desmitis underwent the described tenoscopic desmotomy procedure.
  • Follow-up involved telephone conversations to evaluate soundness and return to exercise.

Results

• Cadaver limb findings:
  • The proximolateral attachment and distal body of the PDAL were completely transected in all 10 limbs.
  • The proximal body of the PDAL was not fully cut in any cadaver limb, indicating some technical limitations.
  • In 4 limbs, accidental damage was observed to the superficial digital flexor tendon, which is a potential complication.
• Clinical case outcomes:
  • Four of the five horses returned to their previous levels of exercise and soundness after surgery.
  • One horse showed immediate postoperative improvement but later developed synovial sepsis, a severe joint infection, and was euthanized after 3 weeks.

Conclusions

• The technique of tenoscopically guided PDAL desmotomy shows promise but has limitations in completely cutting the proximal body of the ligament in cadaver models.
• The procedure can cause inadvertent damage to nearby tendons and requires careful surgical skill.
• Despite challenges seen in cadaver limbs, the technique transferred well to live clinical cases with generally good outcomes and prognoses.
• Diagnosis of PDAL desmitis should be considered significant as it affects performance, and this minimally invasive surgical option provides an effective treatment approach.
• Further refinement and evaluation may improve completeness of ligament cutting and reduce risks of iatrogenic injury.