Arthroscopic Removal of Large Extensor Process Fragments in 18 Friesian Horses: Long-Term Clinical Outcome and Radiological Follow-Up of the Distal Interphalangeal Joint.

This research investigates the long-term clinical and radiological outcomes in Friesian horses after surgical removal of extensor process fragments that occupied a significant portion of their joint surface.

Study Design and Methodology

• The researchers carried out a retrospective case study involving 18 Friesian horses which had undergone arthroscopic removal of large extensor process fragments.
• The arthroscopic examination was conducted with each horse in a dorsal recumbent position (lying on its back) and the affected foot extended. The procedure employed routine surgical entry points (portals).
• The fragment visualization was enhanced using motorized synovial resectors which help in trimming the synovial membrane lining the joints.
• A dissection plane was created between the common digital extensor tendon and the extensor process fragment using sharp lever instruments. In some instances, the process was assisted by motorized burrs and radiofrequency ligament dissection.
• The fragment removal was achieved piecemeal, meaning it was removed in small parts, using Ferris-Smith rongeurs, a type of surgical instrument.
• Data collection involved a review of medical records, preoperative and postoperative radiographs, and owner surveys for contextual details and outcome analysis.

Study Findings

• The arthroscopic removal procedure allowed the successful extraction of large fragments in all 18 horses.
• Long-term clinical follow-up was possible in 17 out of the 18 horses. Of these, 14 resumed their normal activities, while 3 retained some degree of lameness or difficulty in walking.
• Postoperative radiograph examinations showed that the angle between the remodeled extensor process (part of the bone structure in the horse’s foot) and the upper surface of the distal phalanx (the end bone of the toe) had increased. Additionally, subchondral bone (bone beneath the cartilage) remodeling at the fragment bed, or the place where the fragment was removed, was noticeable.

Conclusions

• The study establishes arthroscopic removal as an effective treatment for horses with extensive extensor process fragmentation. The majority of the treated horses showed positive long-term outcomes.
• The findings reveal that the remodeling of the remaining extensor process and the formation of new subchondral bone in the fragment bed can occur, suggesting functional recovery post-surgery.