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. 2021 May 27;8(6):92.
doi: 10.3390/vetsci8060092.

Biplanar High-Speed Fluoroscopy of Pony Superficial Digital Flexor Tendon (SDFT)-An In Vivo Pilot Study

Franziska C Wagner  1 , Kerstin Gerlach  2 , Sandra M Geiger  1 , Claudia Gittel  2 , Peter Böttcher  3 , Christoph K W Mülling  1
Affiliations

Biplanar High-Speed Fluoroscopy of Pony Superficial Digital Flexor Tendon (SDFT)-An In Vivo Pilot Study

Franziska C Wagner et al. Vet Sci. .

Abstract

The superficial digital flexor tendon (SDFT) is the most frequently injured structure of the musculoskeletal system in sport horses and a common cause for early retirement. This project's aim was to visualize and measure the strain of the sound, injured, and healing SDFTs in a pony during walk and trot. For this purpose, biplanar high-speed fluoroscopic kinematography (FluoKin), as a high precision X-ray movement analysis tool, was used for the first time in vivo with equine tendons. The strain in the metacarpal region of the sound SDFT was 2.86% during walk and 6.78% during trot. When injured, the strain increased to 3.38% during walk and decreased to 5.96% during trot. The baseline strain in the mid-metacarpal region was 3.13% during walk and 6.06% during trot and, when injured, decreased to 2.98% and increased to 7.61%, respectively. Following tendon injury, the mid-metacarpal region contributed less to the overall strain during walk but showed increased contribution during trot. Using this marker-based FluoKin technique, direct, high-precision, and long-term strain measurements in the same individual are possible. We conclude that FluoKin is a powerful tool for gaining deeper insight into equine tendon biomechanics.

Keywords: XROMM; collagenase; equine; gait; horse; strain; tendinopathy.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Time schedule of the experimental set-up. Additionally, short clinical examinations were carried out every day within the clinic’s routine.
Figure 2
Figure 2
Computed tomography (CT), FluoKin, and ultrasonographic images of the left forelimb of a pony with implanted tantalum beads. (a) Two tendon markers with metal streak artifact in the CT image, left is dorsal; (b) FluoKin image of the distal forelimb with four tendon markers in the SDFT and five bone markers in the third metacarpal bone; (c) longitudinal and transversal ultrasound image with acoustic shadowing and reverberation artifact due to the implanted beads, left is distal. Arrows mark the implanted beads.
Figure 3
Figure 3
Implantation of the tantalum beads. (a) Left forelimb, lateral (left) and medial (right) view; yellow: bone markers, red: tendon markers with intermarker distances M1 to M4 (#) and M2 to M3 (*); blue: collagenase. (b) Implantation instrument for tendon markers (separated and mounted).
Figure 4
Figure 4
Ultrasonographic image of the left forelimb of a pony, left is lateral: (a) acute (*) and (b) healing (#) tendon lesion of the SDFT (9 weeks after injection of collagenase).
Figure 5
Figure 5
Bar graph of the measured strain of the SDFT of both forelimbs during walk and trot between the implanted tendon markers. Blue arrows: strain behavior in the sound SDFT (right forelimb and “native”). Red dotted arrows: alternated strain behavior compared to “native” and measurements within the right (sound) forelimb. # indicates nonsignificant differences between corresponding measurements in the right, not-insulted forelimb.
Figure 6
Figure 6
Bar graph of the length variation of the tendon markers of both forelimbs during walk and trot. # indicates nonsignificant differences between corresponding amplitudes in the right, not-insulted forelimb.
See this image and copyright information in PMC

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