The effects of polyester (terylene) fibre implants on normal equine superficial digital flexor tendon.

The study examines the effects of polyester (terylene) fibre implants on the normal structure of a horse’s superficial digital flexor tendon. Results indicated that both the procedure and the implants led to changes in the tendon structure, suggesting a persistent risk of injury and implying little to no benefit over standard non-surgical treatments.

Methodology

• The research involved 12 horses with a total of 24 normal forelimb superficial digital flexor (SDF) tendons. These were divided into three groups: unoperated, sham-operated, and those with implanted terylene fibre.
• The horses’ lameness was measured alongside ultrasonographic changes to the SDF tendons at given intervals up to 48 weeks following the operation.
• Post-euthanasia, the SDF tendons were collected for histological and ultrastructural examination.
• These examinations involved checking for alcian blue staining intensity, fibril bundle alignment, cellularity, fascicle separation, and crimp morphology. Additionally, the mass-average diameters of collagen fibrils were measured from electron micrographs and compared among the treatment groups.

Results

• The procedure resulted in short-term lameness in horses with implanted limbs, noticeable up to 8 weeks post-operation.
• The implants were only detectable in 50% of the implanted tendons via ultrasonographic data, and were linked with swelling of the tendons and hypoechoic core lesions in most of the implanted limbs.
• Significant changes were observed in alcian blue staining, cellularity, and crimp morphology in central fascicles of sham-operated and implanted tendons. Furthermore, alteration in fibril alignment was seen in central fascicles of implanted tendons.
• The unoperated tendons maintained their normal histological structure.
• There was no significant difference in the mass-average diameters of collagen fibrils among the sham-operated, implanted, and unoperated tendons.

Conclusions

• Both the sham procedure and the terylene fibre implant led to persistent alterations in the tendons’ structure, observed up to 48 weeks post operation.
• The disorganised connective tissue at both ends of the terylene fibre implants may contribute to a continued risk of injury in the implanted tendons.
• The study concludes that using terylene fibre implants does not provide any significant advantage over standard non-surgical treatments for mild to moderate cases of superficial digital flexor tendonitis in horses.