Case reveal

Findings

• There is complete tear of the manica flexoria of the superficial digital flexor tendon with retraction of the manica laterally. 
• The digital sheath is moderately to severely distended with effusion, and there is synovial proliferation that extends to the deep digital flexor tendon, likely representing adhesion formation.   

• In the medial and lateral oblique sesamoidean ligaments beginning at the origin on the sesamoid bones and extending distally to the level of the metatarsophalangeal joint, the fiber pattern is mildly to moderately disrupted.
• Within the condyles of the third metatarsal bone, more severe medially, the subchondral bone is variably reduced in density and sclerotic with mild focal trabecular bone fluid.
• The metatarsophalangeal joint contains a small amount of effusion and the synovium is mildly prominent.

Conclusions

• Complete tear, manica flexoria of the superficial digital flexor tendon, right hind
• Moderate to marked tenosynovitis, digital sheath, right hind
• Plantar condyle lesions, third metatarsal bone, right hind
• Mild to moderate dorsal margin fraying and fibrillation, deep digital flexor tendon, right hind
• Mild to moderate fiber abnormalities, oblique sesamoidean ligaments, right hind
• Mild synovitis, metatarsophalangeal joint, right hind

MRI Left Pelvic Limb (for comparison)

Ultrasound

A little bit more…

• The manica flexoria represents tendinous tissue originating from the medial and lateral borders of the superficial digital flexor tendon and surrounding the deep digital flexor tendon, forming a sleeve to maintain both tendons in proximity to one another (Findley et al.).
• Located in the proximal third of the digital tendon sheath.
• Tears of the manical flexoria are most prevalent in cobs and pony breeds (Findley et al., Smith & Wright et al.)
• Injuries are most commonly diagnosed using ultrasonography and contrast tenography (Hibner‐Szaltys et al.). MRI and CT may also be used to diagnose maniaca flexoria injuries.

Diagnostic imaging

• Features: Incompletely visualization of the manica flexoria’s margins. The torn edges of the Manica flexoria can be seen floating in tendon sheath effusion, especially is non-weightbearing. The superficial digital flexor tendon may be medially displaced in relation to the deep digital flexor tendon.

• Weight bearing ultrasound evaluations for magical flexoria injuries are reported to be 38% sensitive and 92% specific ((Smith & Wright, 2006)).
• Non–weight-bearing and dynamic ultrasonographic evaluations increases visualization of manica flexoria injuries (Garcia da Fonseca et al.).
• Tears occur more commonly in proximity to the medial or lateral attachment of the manica flexoria to the superficial digital flexor tendon (Findley et al., Garcia da Fonseca et al.)
• In a cadaveric study, MRI was 85% sensitive and 96% sensitive for the identification of tear within the manica flexoria (Aßmann et al.). Another cadaveric study noted a sensitivity of 61% and specificity of 100% (Aßmann et al.).

Tenoscopy

• Treatment of choice for resection of any damaged tissues.
• Has a fair outcome with 67 to 78% of horses returning to their prior athletic activity (Findley et al., Kent et al.).

References

• Garcia da Fonseca, Rita Martins, et al. “Dynamic flexion/extension and non‐weight bearing ultrasonography is helpful for identifying manica flexoria tears in horses.” Veterinary radiology & ultrasound 60.1 (2019): 65-74.
• Hibner‐Szaltys, Maria, et al. “Ultrasonography can be used to predict the location of manica flexoria tears in horses.” Equine Veterinary Education 35.3 (2023): e200-e207.
• Smith, M.R.W. & Wright, I.M. (2006) Noninfected tenosynovitis of the digital flexor tendon sheath: A retrospective analysis of 76 cases. Equine Veterinary Journal, 38(2), 134–141.
• Aßmann, Anton D., et al. “Sensitivity and specificity of 3 Tesla magnetic resonance imaging and multidetector computed tomographic tenography to identify artificially induced soft tissue lesions in the equine cadaveric digital flexor tendon sheath.” Equine Veterinary Education 35.7 (2023): e507-e516.
• Aßmann, Anton, et al. “Does Direct MRI Tenography Improve the Diagnostic Performance of Low-Field MRI to Identify Artificially Created Soft-Tissue Lesions within the Equine Cadaveric Digital Flexor Tendon Sheath?.” Animals 13.24 (2023): 3772.
• Findley, Judith. “Injuries to the digital flexor tendon sheath in the horse.” UK Vet Companion Animal 17.7 (2012): 10-13.
• Kent, A. V., et al. “Improved diagnostic criteria for digital flexor tendon sheath pathology using contrast tenography.” Equine veterinary journal 52.2 (2020): 205-212.