Managing the manica flexoria injuries

Injuries to the manica flexoria (MF) are a common cause of digital flexor tendon sheath (DFTS) tenosynovitis, particularly in cobs and ponies [1]. Diagnosis has been facilitated by novel ultrasonographic techniques and contrast radiography with improved sensitivity and specificity [2; 3]. The two most commonly injured structures are the MF and deep digital flexor tendon (DDFT) [4; 5]. MF tears usually occur in the hindlimb and tear at their medial attachment to the superficial digital flexor tendon (SDFT) [4], in contrast to parasagittal tears of the DDFT which occur predominantly on their lateral aspect and in the forelimbs [6]. It is generally accepted that tears of the MF require surgical management. Of course, without a 100% accurate pre-surgical diagnostic test, one can never be sure how many MF tears are successfully managed conservatively. In the author’s opinion, it is the instability of a torn MF that perpetuates the tenosynovitis. During surgery, and demonstrated with novel ultrasonographic techniques [2], the torn MF is usually thicker thereby making it more prone to becoming trapped in the fetlock canal during fetlock extension. The majority of tears appear to initiate at their distal attachment to the SDFT and the resultant free border recoils proximally. We have also seen biaxial tears with both medial and lateral attachments severed. In these cases, the MF recoils proximally becoming adhered to the proximal aspect of the DFTS. This adherence appears to stabilise the MF and in these horses lameness can be mild. Nevertheless, a residual low-grade lameness is likely with a persistent tenosynovitis and accompanying effusion. Conservative management of MF tears should be considered if no pathology is identified during contrast tenography or ultrasonography, or if there are insufficient funds for tenoscopic surgery.

Conservative management will consist of rest with or without medication of the DFTS, usually with corticosteroid +/- hyaluronic acid. Corticosteroid medication invariably improves both the synovial effusion and lameness, and this improvement may be sustained for many weeks. However, with MF tears, lameness will usually recur and this will reinforce the case for tenoscopic surgery.

Digital flexor tendon sheath tenoscopy is usually performed with the horse in lateral recumbency with the affected limb uppermost. The author will routinely place an Esmarch bandage proximal to the carpus/tarsus to reduce bleeding during surgery. The hoof is covered with a sterile glove and bandage before an extremity drape is placed over the limb and fixed at the proximal metacarpus/metatarsus level. A palmar/plantar nerve block placed proximal to the DFTS improves comfort during surgery and recovery. [...]