46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
147
ligament was transected. The #12 blade would then be advanced further distally
until the transection was continuous with the endoscope portal. The #12 blade was
then removed and reintroduced to the tendon sheath angled proximally. Using the
rigid endoscope to protect the SDFT and to separate it and the PAL the desmotomy
was then performed proximally in a similar fashion until complete transection had
been achieved.
Following PAL desmotomy tears of the manica flexoria or deep digital flexor tendon
were identified. Tears of the manica flexoria were treated by transecting the lateral
border of the manica flexoria using a #12 blade or a 14-gauge needle. Often this
required a third portal to be established on the lateral aspect of the tendon sheath at
the level of the distal end of the manica flexoria. Once resected, a fourth portal was
established in the proximal part of the tendon sheath. Rongeurs were introduced
through this portal and were used to grasp the distal and lateral edge of the manica
flexoria and maintain tension on it. The medial border of the manica was then
resected using a 5.2 mm suction punch (Dyonics Smith & Nephew), occasionally
augmented with use of a 14-gauge needle. Resection was usually performed dorsal
to the deep digital flexor tendon, with tension on the manica flexoria used to roll the
superficial digital flexor tendon medially. Resection of the medial border was
continued into the proximal border. To maintain tension on the manica flexoria the
proximal portal was enlarged, which allowed the manica flexoria to be exteriorised.
The final resection of the lateral part of the proximal border was usually performed
by external dissection. At the completion of surgery the tendon sheath was lavaged
extensively and medicated with 300mg hyaluronic acid (HY-50, Dechra).
Linear tears of the deep digital flexor tendon were debrided of torn and prolapsed
tendon fibres. This was accomplished using a motorised synovial resector. Suction
affixed to the resector can increase the aggression of the instrument but is seldom
necessary. It is almost invariably necessary to have two portals, in the proximal
tendon sheath to resect the majority of the tear, and one extremely proximal,
proximal to the manica flexoria, to allow the resector to come underneath the
manica. Tears generally run from the mesotenon of the deep digital flexor tendon to
distal to the sesamoidean canal. There are two “problems” with this surgery. The
first is that once the fibres are resected, two flaps of tendon remain, either side of
the tear. Generally I choose to resect these flaps as well, to try to produce a
flattened edge to the deep digital flexor tendon. However, this is determined partly
by the depth of the tear – too much tendon is removed from the deep digital flexor
tendon if all the tissue surrounding a deep tear is resected. The second is that the
job is never finished. No matter how smooth an edge is created, once examined a
moment or so later, there are more loose fibres coming away from the tendon.
Arensburg (2010) described coblation. This is a form o f radiosurgery, to melt the
collagen and form a nice smooth edge to the tendon. However, though not
significant, the results were worse than those of horses that did not have coblation
(52% of horses returning to the same or higher level of activity when coblation was
not used, compared to 26% when coblation was used). This is as anticipated – the
use of radiofrequency was very popular in human arthroscopy due to the good
cosmetic appearance. However, follow up studies have been very negative,
confirming that the temperature to melt the collagen is also associated with cell
death. These authors also showed a better (non significant) success rate when
horses were treated by annular ligament desmotomy.
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