Morphologic and morphometric features of the calcaneal insertions of the superficial digital flexor tendon in the horse.

This research paper examines the detailed structure and measurements of the calcaneal insertions of the superficial digital flexor tendon (SDFT) in horses, previously not well-defined, highlighting their unique features and role in clinical lesions identified.

Objective of the Study

• The study aimed at an exact characterization and measurement of the superficial digital flexor tendon’s (SDFT) calcaneal insertions in horses. These evaluations are necessitated due to inconsistent and insufficient descriptions of these structures previously, to better understand their functional and pathogenic role in displacement of the SDFT from the calcaneal tuber.

Methodology

• Studies were carried out on 10 normal cadaveric hindlimbs through dissection methods.
• The anatomical structural locations were photographed for measurability at repeatable locations.
• Statistical comparison of the varying dimensions of the SDFT at various locations was performed using a paired student t-test.

Results of the Study

• The study illuminates the independence of calcaneal insertions from the overlying tarsal insertions of the biceps femoris and semitendinosus.
• These aforementioned muscular structures blend into the fibrocartilaginous cap (FCC) of the SDFT surface before inserting dorsal to the SDFT’s insertion on the calcaneal tuber.
• It has been observed that the SDFT’s lateral insertion is larger in cross-sectional area (median: 219 mm²) at its origin from the FCC than its medial counterpart (median: 159 mm²).
• The lateral insertion also showcased a more complex fibre alignment.
• The point of attachment for the SDFT on the lateral site of the calcaneal tuber is dorsolaterally situated relative to the gastrocnemius tendon’s insertion. It has a larger insertion area (median: 525 mm²) than the medial insertion (median: 428 mm²), which inserts distal to the gastrocnemius insertion.

Conclusions

• The research revealed that the SDFT’s calcaneal insertions have multiple complex features.
• The observed morphological and cross-sectional area disparities are likely contributing factors to the clinical lesions identified in these locations.