Objective—To determine response of interleukin-1α
(IL-1α)-conditioned equine articular cartilage explants
to insulin-like growth factor-1 (IGF-1).
Sample Population—Cartilage from the trochlea and
condyles of the femur of a clinically normal 4-year-old
Procedure—Effects of IGF-1 (0 to 500 ng/ml) after
addition of IL-1α were evaluated by assessing matrix
responses, using a sulfated glycosaminoglycan (GAG)
assay, matrix 35SO4 GAG incorporation, and release of
GAG. Mitogenic response was assessed by 3H-thymidine
incorporation into DNA and fluorometric assay of
total DNA concentration.
Results—Human recombinant IL-1α (40 ng/ml)
increased the amount of labeled GAG released and
decreased labeled and total GAG remaining in
explants, and IL-1α decreased mitogenic response.
Addition of IGF-1 counteracted effects seen with IL-1α
alone. In general, IGF-1 decreased total and labeled
GAG released into the medium, compared with IL-1α-
treated explants (positive-control sample). Values for
these variables did not differ significantly from those
for negative-control explants. A significant increase in
total and newly synthesized GAG in the explants at
termination of the experiment was observed with
500 ng of IGF-1/ml. Labeled GAG remaining in
explants was greater with treatment at 50 ng of
IGF-1/ml, compared with treatment with IL-1α alone.
Concentrations of 200 ng of IGF-1/ml abolished
actions of IL-1α and restored DNA synthesis to values
similar to those of negative-control explants.
Conclusions and Clinical Relevance—IGF-1 at 500
ng/ml was best at overcoming detrimental effects
associated with IL-1α in in vitro explants. These beneficial
effects may be useful in horses with
osteoarthritis. (Am J Vet Res 2000;61:436–441)
Objective—To determine relative amounts of mRNA
expression of aggrecan, type-II collagen, matrix metalloproteinase
(MMP) 1, and MMP3 in articular cartilage
and synovial membrane samples from healthy
equine joints and joints with osteoarthritis (OA) and to
compare results of Northern blot hybridization with
results of a reverse transcriptase-polymerase chain
reaction (RT-PCR) assay.
Sample Population—Articular cartilage samples
from 8 pairs of joints (1 with OA and 1 healthy) from
6 horses and synovial membrane samples from 6
pairs of joints from 5 horses.
Procedure—RNA was extracted from samples by
use of a modified Trizol procedure. Northern blot
hybridization and the RT-PCR assay were performed;
results were quantitated by use of glyceraldehyde 3-
phosphate dehydrogenase as an internal standard.
Results—Articular cartilage samples from joints with
mild or moderate OA yielded less total RNA than samples
from joints with severe OA. Northern blot
hybridization indicated that type-II collagen mRNA
expression in articular cartilage samples from joints
with OA was significantly greater than expression in
samples from healthy joints. The RT-PCR assay identified
low levels of MMP3 mRNA expression in 4 of 8
sets of articular cartilage samples and 4 of 6 sets of
synovial membrane samples, whereas Northern blot
hybridization identified MMP3 mRNA expression in
only 1 of 6 sets of articular cartilage samples and 1 of
6 sets of synovial membrane samples.
Conclusions—A RT-PCR assay is more sensitive than
Northern blot hybridization for detection of MMP3
mRNA expression in articular cartilage and synovial
membrane and requires smaller samples. (Am J Vet
Objective—To evaluate the outcome of horses with
large fragments of the extensor process of the distal
phalanx that were removed by use of arthrotomy.
Animals—14 horses with large fragments of the
extensor process of the distal phalanx.
Procedure—Medical records for horses with large
fragments of the extensor process that were
removed by use of arthrotomy were reviewed. Data
retrieved from medical records included signalment,
use of horse, affected limb, lameness history, lameness
examination findings, radiographic findings, surgical
technique, and outcome. Follow-up evaluation
was obtained by telephone interview.
Results—Most affected horses were < 5 years old
and had a history of chronic lameness. Lameness
grade ranged from 1/5 to 4/5. Fragments involved 20
to 45% of the dorsopalmar articular surface of the distal
phalanx. Eight of 14 horses had a successful outcome.
Outcome was not associated with age, duration
or severity of lameness, or fragment size.
Conclusions and Clinical Relevance—Despite
involvement of a large portion of the articular surface
and use of arthrotomy, joint instability and permanent
soft tissue injury was not a problem in most horses.
Outcome may be improved by selection of horses
with lameness of < 2 years' duration and careful management
after surgery. A fair prognosis may be anticipated
for removal of large fragments of the extensor
process via arthrotomy. (J Am Vet Med Assoc 2000;
Objectives—To determine concentrations of matrix
metalloproteinase (MMP)-2 and -9 in synovial fluid;
and mRNA expression of MMP-1, -13, and -3; interleukin[
IL]-1α and β; and tumor necrosis factor(TNF)-α
in synovial membrane and articular cartilage from
horses with naturally occurring joint disease.
Sample Population—Synovial fluid (n = 76), synovial
membrane (59), and articular cartilage (45) from 5 clinically
normal horses and 55 horses with joint disease
categorized as traumatic (acute [AT] or chronic [CT]),
osteochondritis dissecans (OCD), or septic (S).
Procedure—Synovial fluid gelatinase concentrations
were analyzed, using zymography. Synovial membrane
and articular cartilage mRNA expression for
MMP-1, -3, and -13, IL-1α and β, TNF-α, type-II collagen,
and aggrecan were analyzed, using quantitative
reverse transcriptase-polymerase chain reaction.
Results—Synovial fluid pro-MMP-2 concentration
was significantly higher in diseased joints than normal
joints. Septic joints had significantly higher concentrations
of pro and active MMP-9. Stromelysin-1 was
expressed in ≥ 80% of synovial membrane and articular
cartilage samples and was strongly influenced by
age. Collagenases were rarely expressed, with MMP-
13 expressed only in diseased joints. Interleukin-1β
expression was significantly higher in all OCD samples
and was influenced by age. Tumor necrosis factor-
α expression was significantly higher in cartilage
from joints with AT and OCD. There was no correlation
between MMP or cytokines and type-II collagen
or aggrecan expression.
Conclusions and Clinical Relevance—Matrix metalloproteinase-
2 and -3 are abundant in naturally occurring
joint disease and normal joints. Interleukin-1β and
TNF-α may be important in the pathogenesis of OCD.
Age affects MMP and IL-1β concentrations. (Am J Vet
Objective—To assess the long-term clinical outcome
of horses with distal tarsal osteoarthritis (OA) in which
a 3-drill-tract technique was used to induce arthrodesis
of the affected joints, identify any preoperative or
operative factors associated with outcome, and
describe any complications associated with the technique.
Procedure—Medical records were reviewed for information
on signalment, use, history, physical and
lameness examination findings, surgical technique,
and postoperative care. Radiographs were examined,
and severity of OA was graded. Follow-up information
was obtained through telephone interviews with
owners at least 13 months after the procedure.
Results—32 (59%) horses had a successful outcome,
6 (11%) improved but were not sound after
surgery, and 16 (30%) did not improve following
surgery. Outcome was negatively associated with the
previous use of intra-articular injections. Few postoperative
complications were evident.
Conclusions and Clinical Relevance—Results suggest
that distal tarsal OA in horses can be successfully
treated by means of distal tarsal arthrodesis with
a 3-drill-tract technique. Horses with advanced distal
tarsal OA are likely to have poorer outcomes, and the
procedure will likely be of minimal benefit in horses
with concomitant causes of hind limb lameness prior
to surgery and in horses with preexisting proximal
intertarsal joint disease. (J Am Vet Med Assoc 2003;