Objective—To determine the outcome of horses
with basal fractures of the proximal sesamoid bone
from which a fracture fragment involving a portion of
the base of the bone was removed arthroscopically
and to determine whether fragment size was associated
Procedure—Dorsopalmar and axial-abaxial lengths of
the fracture fragment were measured on the dorsopalmar
and mediolateral radiographic views,
respectively, and percentage of the base of the
sesamoid bone involved was estimated. Fractures
were classified as grade 1 (≤ 25% of the base
involved) or grade 2 (> 25% but < 100% of the base
involved). Outcome was classified as successful if the
horse started at least 2 races or unsuccessful if the
horse started only 1 race or failed to return to racing.
Results—There were 24 racehorses and 2 nonracehorses.
Twelve (50%) of the racehorses returned to
racing and started at least 2 races. Eight of 14 horses
with grade-1 fractures and 4 of 10 horses with grade-
2 fractures had a successful outcome. Ten of 16 horses
without associated articular disease had successful
outcomes, compared with 2 of 8 horses with associated
articular disease. However, fragment size and
presence of associated articular disease were not significantly
associated with outcome.
Conclusions and Clinical Relevance—Horses with
basal fractures of the proximal sesamoid bone from
which a fracture fragment involving a portion of the
base of the bone is removed arthroscopically have a
fair prognosis for return to racing. (J Am Vet Med
Objective—To determine the effects of exercise at an early age on tissues in the metacarpophalangeal joints of horses.
Animals—Twelve 18-month-old horses.
Procedures—All horses were pasture reared, but 6 horses had additional exercise starting at 3 weeks of age until 18 months of age. At that time, computed tomography, articular cartilage metabolism evaluation, and histologic assessments of synovial membrane, articular cartilage, and subchondral bone were performed.
Results—Exercised horses had fewer gross lesions, less articular cartilage matrix staining in the dorsal aspect of the condyle, greater bone fraction in the dorsolateral aspect of the condyle, and higher bone formation rate, compared with nonexercised horses.
Conclusions and Clinical Relevance—Exercise at a young age may be protective to joints, although more research is needed to characterize changes in articular cartilage matrix. Results suggested that exercise can be safely imposed at an early age.
Objective—To determine whether decreases in peak
vertical force of the hind limb after transection of the
cranial cruciate ligament (CrCL) would be indicative of
medial meniscal damage in dogs.
Animals—39 purpose-bred adult male Walker
Procedure—The right CrCL was transected arthroscopically.
Force plate measurements of the right
hind limb were made prior to and 2, 4, 10, and 18
weeks after transection of the CrCL. Only dogs with
≥ 10% decreases in peak vertical force after week 2
were considered to have potential meniscal damage.
Dogs that did not have ≥ 10% decreases in peak vertical
force at any time point after week 2 were
assigned to group 1. Group 2 dogs had ≥ 10%
decreases in peak vertical force from weeks 2 to 4
only. Group 3 and 4 dogs had ≥ 10% decreases in
peak vertical force from weeks 4 to 10 only or from
weeks 10 to 18 only, respectively. Damage to menisci
and articular cartilage was graded at week 18, and
grades for groups 2 to 4 were compared with those
of group 1.
Results—The percentage change in peak vertical
force and impulse area was significantly different in
groups 2 (n = 4), 3 (4), and 4 (4) at the end of each
measurement period (weeks 4, 10, and 18, respectively)
than in group 1 (27). The meniscal grade for
groups 2 to 4 was significantly higher than for group
1. A ≥ 10% decrease in peak vertical force had sensitivity
of 52% and accuracy of 72% for identifying
dogs with moderate to severe medial meniscal damage.
Conclusions and Clinical Relevance—In dogs with
transected or ruptured CrCLs, force plate analysis can
detect acute exacerbation of lameness, which may be
the result of secondary meniscal damage, and provide
an objective noninvasive technique that delineates
the temporal pattern of medial meniscal injury.
( Am J Vet Res 2005;66:156–163)
Objective—To compare articular cartilage from horses
with naturally developing osteochondrosis (OC)
with normal articular cartilage and healing cartilage
obtained from horses with experimentally induced
Sample Population—109 specimens of articular cartilage
from 78 horses.
Procedure—Morphologic characteristics, proteoglycan
(PG), and type II collagen were analyzed in articular cartilage
of OC specimens (group 1), matched healing cartilage
obtained 40 days after experimentally induced
osteochondral fractures (group 2), and matched normal
cartilage from the same sites (group 3).
Results—79 specimens of OC cartilage were
obtained from horses. Ex vivo PG synthesis was significantly
greater in the femoral cartilage, compared
with synthesis in the tibial cartilage, and significantly
greater for groups 1 and 2, compared with group 3.
For groups 1 and 2, femoral fragments had significantly
greater PG content, compared with PG content
in tibial fragments. Keratan sulfate content was significantly
less in group 3, compared with groups 1 and
2. Cartilage from the OC specimens had loss of structural
architecture. The OC tissue bed stained positive
for chondroitin sulfate and type II collagen, but the
fracture bed did not.
Conclusions and Clinical Relevance—Our analyses
could not distinguish articular cartilage from horses
with OC and a healing fracture. Both resembled an
anabolic, reparative process. Immunohistochemical
analysis suggested a chondromyxoid tissue in the OC
bed that was morphologically similar to fibrous tissue
but phenotypically resembled hyaline cartilage. Thus,
tissue in the OC bed may be degenerative cartilage,
whereas tissue in the fracture bed may be reparative
fibrous callus. (Am J Vet Res 2005;66:1881–1890)
Objective—To evaluate the use of serum concentrations
of biochemical markers of bone metabolism
(osteocalcin [OC], bone-specific alkaline phosphatase
[BS-ALP], and deoxypyridinoline [DPYR]) to compare
healing in infected versus noninfected fractures and in
fractures with normal repair versus delayed (nonunion)
repair in rabbits.
Animals—32 female 9- to 10-month-old New Zealand
Procedure—A femoral fracture defect was made in
each rabbit. Rabbits were assigned to the following
groups: the bone morphogenetic-2 gene treatment
group with either noninfected nonunion or infected (ie,
inoculation of defects with Staphylococcus aureus)
nonunion fractures or the luciferase (control) gene
treatment group with either noninfected nonunion or
infected nonunion fractures. Serum samples were
obtained before surgery (time 0) and 4, 8, 12, and 16
weeks after surgery. Callus formation and lysis grades
were evaluated radiographically at 16 weeks.
Results—Serum OC and BS-ALP concentrations
decreased from time 0 at 4 weeks, peaked at 8
weeks, and then decreased. Serum DPYR concentration
peaked at 4 weeks and then decreased, independent
of gene treatment group or fracture infection
status. Compared with rabbits with noninfected fractures,
those with infected fractures had lower serum
OC and BS-ALP concentrations at 4 weeks, higher
serum OC concentrations at 16 weeks, and higher
serum DPYR concentrations at 4, 8, and 16 weeks.
Combined serum OC, BS-ALP, and DPYR concentrations
provided an accuracy of 96% for prediction of
fracture infection status at 4 weeks.
Conclusions and Clinical Relevance—Measurement
of multiple serum biochemical markers of bone
metabolism could be useful for clinical evaluation of
fracture healing and early diagnosis of osteomyelitis.
( J Am Vet Med Assoc 2003;64:727–735)
Objective—To evaluate the temporal pattern of
prostaglandin (PG) E2 concentrations in synovial fluid
after transection of the cranial cruciate ligament
(CCL) in dogs and to correlate PGE2 concentrations
with ground reaction forces and subjective clinical
variables for lameness or pain.
Animals—19 purpose-bred adult male Walker
Procedure—Force plate measurements, subjective
clinical analysis of pain or lameness, and samples of
synovial fluid were obtained before (baseline) and at
various time points after arthroscopic transection of
the right CCL. Concentrations of PGE2 were measured
in synovial fluid samples, and the PGE2 concentrations
were correlated with ground reaction
forces and clinical variables.
Results—The PGE2 concentration increased significantly
above the baseline value throughout the entire
study, peaking 14 days after transection. Peak vertical
force and vertical impulse significantly decreased by
day 14 after transection, followed by an increase over
time without returning to baseline values. All clinical
variables (eg, lameness, degree of weight bearing,
joint extension, cumulative pain score, effusion score,
and total protein content of synovial fluid, except for
WBC count in synovial fluid) increased significantly
above baseline values. Significant negative correlations
were detected between PGE2 concentrations
and peak vertical force (r, –0.5720) and vertical
impulse (r, –0.4618), and significant positive correlations
were detected between PGE2 concentrations
and the subjective lameness score (r, 0.5016) and
effusion score (r, 0.6817).
Conclusions and Clinical Relevance—Assessment
of the acute inflammatory process by measurement
of PGE2 concentrations in synovial fluid may be correlated
with the amount of pain or lameness in dogs.
(Am J Vet Res 2004;65:1269–1275)
Objective—To assess the clinical, biochemical, and histologic effects of extracorporeal shock wave therapy (ESWT) in the treatment of horses with experimentally induced osteoarthritis (OA).
Animals—Twenty-four 2- to 3-year-old horses without evidence of lameness.
Procedures—OA was induced arthroscopically in 1 middle carpal joint of each horse. Fourteen days after induction of OA, horses were treated with a sham ESWT probe (placebo; n = 8), polysulfated glycosaminoglycan (PSGAG) administered IM every 4 days for 28 days as a positive control treatment (8), or ESWT administered on days 14 and 28 with a focused shock wave unit (8). Evaluations included clinical assessments of degree of lameness every 2 weeks and weekly synovial fluid analyses. Horses were euthanized 70 days after induction of OA, and gross pathologic and histologic examinations of cartilage and synovial membrane specimens were performed at necropsy. A generalized linear mixed model was used to compare outcomes among treatment groups.
Results—No adverse treatment-related events were detected in any horse. The degree of lameness in horses treated with ESWT improved significantly, compared with the degree of lameness in placebo- or PSGAG-treated horses. No disease-modifying effects were evident in results for synovial fluid, synovial membranes, or cartilage from the ESWT- or PSGAG-treated horses.
Conclusions and Clinical Relevance—Although a disease-modifying effect of ESWT was not detected, the significant clinical effect of ESWT suggested that this modality should be considered for treatment of horses with OA in combination with another modality that does affect the disease process.
Objective—To use microarray analysis to identify genes that are differentially expressed in horses with experimentally induced osteoarthritis.
Procedures—During arthroscopic surgery, a fragment was created in the distal aspect of the radiocarpal bone in 1 forelimb of each horse to induce osteoarthritis. At day 14 after osteoarthritis induction, horses began exercise on a treadmill. Blood and synovial fluid samples were collected before and after surgery. At day 70, horses were euthanized and tissues were harvested for RNA analysis. An equine-specific microarray was used to measure RNA expression in peripheral WBCs. These data were compared with mRNA expression (determined via PCR assay) in WBCs, cartilage, and synovium as well as 2 protein biomarkers of cartilage matrix turnover in serum and synovial fluid.
Results—A metalloproteinase domain-like protein decysin-1 (ADAMDEC1), glucose-regulated protein (GRP) 94, hematopoietic cell signal transducer (HCST), Unc-93 homolog A (hUNC-93A), and ribonucleotide reductase M2 polypeptide (RRM2) were significantly differentially regulated in WBCs of horses with osteoarthritis, compared with values prior to induction of osteoarthritis. There was correlation between the gene expression profile in WBCs, cartilage, and synovium and the cartilage turnover proteins. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in WBCs were correlated when measured via microarray analysis and PCR assay.
Conclusions and Clinical Relevance—Expression of ADAMDEC1, GRP94, HCST, hUNC-93A, and RRM2 was differentially regulated in peripheral WBCs obtained from horses with experimentally induced osteoarthritis. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in peripheral WBCs has the potential for use as a diagnostic aid for osteoarthritis in horses.
Objective—To assess clinical, biochemical, and histologic effects of polysulfated glycosaminoglycan (PSGAG) or sodium hyaluronan administered intra-articularly in treatment of horses with experimentally induced osteoarthritis.
Procedures—Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses received hyaluronan (20 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight horses received PSGAG (250 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight control horses received 2 mL of saline (0.9% NaCl) solution and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Clinical, radiographic, synovial fluid analysis, gross, histologic, histochemical, and biochemical findings were evaluated.
Results—No adverse treatment-related events were detected. Induced osteoarthritis caused a substantial change in lameness, response to flexion, joint effusion, and radiographic findings, and of these, synovial fluid effusion was reduced with PSGAG, compared with control horses. No changes in clinical signs were seen with PSGAG or hyaluronan, compared with control horses. Histologically, the degree of synovial membrane vascularity and subintimal fibrosis was significantly reduced with PSGAG treatment, compared with controls. Histologically, significantly less fibrillation was seen with hyaluronan treatment, compared with controls.
Conclusions and Clinical Relevance—Results indicated that PSGAG and hyaluronan had beneficial disease-modifying effects and are viable therapeutic options for osteoarthritis in horses.
Objective—To compare the mesenchymal stem cell (MSC) yield and chondrogenic and osteogenic differentiation from 5- and 50-mL bone marrow aspirates from horses.
Animals—Six 2- to 5-year-old mixed-breed horses.
Procedures—2 sequential 5-mL aspirates were drawn from 1 ilium or sternebra. A single 50-mL aspirate was drawn from the contralateral ilium, and 2 sequential 50-mL aspirates were drawn from a second sternebra. The MSC yield was determined through the culture expansion process. Chondrogenesis and osteogenesis were evaluated by means of conventional laboratory methods.
Results—The second of the 2 sequential 50-mL sternal aspirates yielded few to no MSCs. Independent of location, the highest density of MSCs was in the first of the 2 sequential 5-mL fractions, although with subsequent culture expansion, the overall yield was not significantly different between the first 5-mL and first 50-mL fractions. Independent of location, chondrogenesis and osteogenesis were not significantly different among fractions. Independent of fraction, the overall cell yield and chondrogenesis from the ilium were significantly higher than that from the sternum.
Conclusions and Clinical Relevance—This study failed to detect an additional benefit of 50-mL aspirates over 5-mL aspirates for culture-expanding MSCs for equine clinical applications. Chondrogenesis was highest for MSCs from ilial aspirates, although it is not known whether chondrogenesis is indicative of activation of other proposed pathways by which MSCs heal tissues.