Healing characteristics of deep digital flexor tenorrhaphy within the digital sheath of horses.

The research study investigates the healing process of deep digital flexor tenorrhaphy, a tendon surgery, within the digital sheath area in horses. The focus is on how this procedure performs in healing the tendon and its impact on the animals’ mobility.

Methods

The study was carried out on five mature horses through an experimental approach which employed a surgical procedure. The right thoracic limb of each horse underwent deep digital flexor tenorrhaphy within the digital sheath, and then the limbs were held in partial flexion in a short limb cast for a period of 6 weeks. After this, the horses were fitted with extended heel shoes for additional support for a further 14 weeks.

The healing process was monitored through sequential ultrasonographic examinations and the use of the limb was examined via force plate analysis. At the end of a 26 weeks period, the repair site’s mechanical strength and morphologic characteristics were evaluated.

Results

• A gap formation that was noticeable in unloaded limbs was first noted at the three week point. This gap was significantly increased at the six week point, and by 26 weeks, it had reached 5 cm.
• The differentiation between the deep and superficial flexor tendons lessened as the transected ends of the tendons adhered to the superficial flexor tendon’s dorsal surface.
• There was a reduction in the intrathecal space due to the formation of fibrous tissue.
• The mean maximum load to failure of the repair tissue was noted as 4,616 +/- 3,556 N, and the mean stress was 12.99 +/- 2.78 MPa.
• The repair generally failed at the adhesion point between the transected tendon and the superficial flexor tendon.

Conclusions

• The researchers concluded that conducting intrathecal tenorrhaphy with external coaptation (in partial limb flexion) for 6 weeks led to gap healing, a fibrous adhesion between the deep and superficial flexor tendons, a reduction in the intrathecal space due to fibrous tissue, and a horse sound at 26 weeks.
• The study’s results suggest that without better methods for immobilizing the deep digital flexor tendon, intrathecal tenorrhaphy may not lead to first intention tendon healing. This could negatively impact the long term mobility and health of the horses who undergo this procedure.