46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
35
achieve this. An intra-operative radiograph is taken to confirm screw position and
length, taking care to ensure the screw has crossed the growth plate but is not
impinging on the joint. Following measuring and tapping, a 4.5 mm screw of
appropriate length is inserted. The skin is closed and a bandage placed. Foals
anaesthetised for transphyseal screw placement receive procaine penicillin and
phenylbutazone perioperatively, and tetanus prophylaxis as required. Bandages
placed during surgery are replaced the following day and the foal is discharged from
hospital. Sutures are removed at 10-14 days post operatively, and bandages are
maintained until suture removal. Depending on the circumstance of the farm and
the severity of the deviation, foals are usually kept in a box or small yard until suture
removal. In our practice most transphyseal screws are removed under general
anaesthesia, although removal of carpal screws in well-behaved foals may be
performed standing. Foals receive procaine penicillin and phenylbutazone
perioperatively and bandages placed during surgery are replaced the following day
and the foal is discharged. Sutures are removed at 10-14 days. Exercise is usually not
restricted following implant removal.
Periosteal strips for fetlock joints are rarely performed in our practice, fetlock ALD
are almost solely managed by a single transphyseal screws and appropriate trimming
and/or acrylic extensions. Most transphyseal screws are placed for fetlock ALD
between 2 and 5 months of age, although this can vary depending on the severity of
the deformity and rate of deterioration. If the foal is older and requires correction,
radiographs are performed to assess if the growth plate appears to have closed. I
have been pleasantly surprised at how many foals older than 5 months of age may
still have some degree of correction if the growth plate still demonstrates
radiolucency on the radiographs. We avoid placing transphyseal screws across the
carpus before 6-8 months of age in most circumstances. The exception would be if
the ALD of the carpus is severe and rapidly deteriorating. The collective clinical
experience of our practice believes that early growth retardation of the carpus can
result in a deviation in a previously straight fetlock. If the foal has concurrent ALDs
of both carpi and fetlocks, we focus on correcting the fetlock ALD with transphyseal
screws, and watch and wait on the knees. Many of these foals will correct the ALD
of the carpus as they approach weanling age.
In the last 3 seasons (2010-2013) 81 foals have had transphyseal screws placed in our
practice. Eighty six per cent were placed in the fetlocks, 97% for varus deformities.
At least one quarter of these foals also had acrylic extensions placed. Complications
were recorded in 13 foals; these included overcorrection in 2, implant infection
necessitating early removal in 1 foal, and some evidence of implant infection noted at
removal (either screw loose, purulent material around screw head or evidence of
lysis on radiographs) in 4 foals. The remainder of the complications (5) was difficulty
in screw removal, either because the screw was bent or the screw head was
covered in bone. One foal required a second, longer screw to be placed to re-cross
the growth plate. There was almost equal incidence of recorded complications in
both 3.5 and 4.5 mm screws. One foal was euthanized due to persistence of severe
ALD and associated lameness. For fetlock ALD, the average length of time implants
remained in place was 84.1 days (range 24-173 days). For carpal ALD implants
remained in place an average of 94.8 days (range 29-192 days). This is longer than is
reported in the literature,5 and is likely associated with late removal (i.e. past the
time of correction). Review of radiographs taken for yearling sales revealed there
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