Objective—To evaluate the use of hydrothermal ablation
of articular cartilage for arthrodesis in horses
through investigation of the effects of joint lavage
with physiologic saline (0.9% NaCl) solution (80°C) for
various treatment times on chondrocyte viability in
the articular cartilage of the metacarpophalangeal and
metatarsophalangeal joints of cadaveric horse limbs.
Sample Population—7 pairs of metacarpophalangeal
and 8 pairs of metatarsophalangeal joints
from 8 Thoroughbreds.
Procedure—The horses were euthanatized for reasons
unrelated to musculoskeletal disease. On a random
basis, 1 joint of each pair underwent intra-articular
lavage for 5, 10, or 15 minutes with heated saline
solution (80°C); the other joint underwent sham treatment
of similar duration with saline solution at 22°C
(control). Cartilage samples from the distal articular
surface of metacarpus III (or metatarsus III), the proximal
surface of the proximal phalanx, and the lateral
and medial proximal sesamoid bones were assessed
for chondrocyte viability via confocal microscopy and
viability staining following enzymatic digestion.
Results—Compared with the control joints, findings
of both viability assays indicated that the percentage
of sites containing viable chondrocytes in heat-treated
joints was decreased. Treatment hazard ratios of 0.048
(confocal microscopy) and 0.2 (digestion assay) were
estimated. Histologically, periarticular soft tissues had
minimal detrimental effects after heat treatment.
Conclusions and Clinical Relevance—Ex vivo intraarticular
lavage with saline solution at 80°C resulted in
the death of almost all articular chondrocytes in the
joint. This technique may be a satisfactory method for
extensive cartilage ablation when performing
arthrodesis by minimally invasive techniques. (Am J Vet Res 2005;66:36–42)
Objective—To compare effects of synovectomy performed
by use of monopolar radiofrequency energy
(MRFE) versus mechanical debridement in rabbits
with induced inflammatory arthritis.
Animals—25 mature female New Zealand White rabbits.
Procedure—Inflammatory arthritis was induced in
both femoropatellar joints of each rabbit. Joints then
were treated by mechanical debridement or MRFE
treatment or served as sham-operated controls.
Rabbits were euthanatized 2 weeks or 3 months after
surgery. Biopsy specimens of synovium were analyzed
by use of light microscopy.
Results—At 2 weeks after surgery, samples from
MRFE-treated joints had fewer plasma cells and more
heterophils than the other 2 groups and more lymphocytes
than sham-operated controls, whereas
samples from mechanically debrided joints had
greater numbers of lymphocytes and heterophils than
sham-operated controls. At 3 months after surgery,
samples from MRFE-treated joints had fewer plasma
cells than sham-operated controls, more heterophils
than mechanically debrided and sham-operated controls,
and more macrophages than mechanically
debrided joints. There was no difference in synovial
ablation, synovial proliferation, or fibrosis among the 3
groups at 2 weeks or 3 months after surgery.
Conclusions and Clinical Relevance—Analysis of
results of this study documented a similar degree of
synovial ablation when comparing use of MRFE to
mechanical debridement. In rabbits with this method
of induced inflammatory arthritis, there were no
detectable benefits of MRFE or mechanical debridement
on the synovium, compared with results for
sham-operated control joints, at 2 weeks and 3
months after surgery for most of the synovial variables
evaluated. ( Am J Vet Res 2004;65:573–577)
Objective—To compare 2 methods of quantitating chondrocyte viability and to determine chondrocyte response to thermal injury over time.
Sample Population—108 stifle joints from 54 adult rats.
Procedures—Cartilage from the distal aspect of the femur was treated ex vivo with radiofrequency energy at a probe setting that would result in immediate partial-thickness chondrocyte death; untreated sections served as controls. Explants were cultured, and cell viability was compared by use of lactate dehydrogenase (LDH) histochemical staining and calcein AM and ethidium homodimer-1 confocal laser microscopy (CLM) cell viability staining. Terminal deoxynucleotidyl transferase–mediated X-dUTP nick end labeling (TUNEL) was used to detect apoptosis. All labeling studies were performed 0, 1, 3, 7, 14, and 21 days after treatment.
Results—In the treated tissues, a greater percentage of viable cells were found with CLM, compared with LDH staining. This result contrasted that of control tissues in which LDH staining indicated a greater percentage of live cells than CLM. The greatest number of TUNEL-positive chondrocytes was present at day 3, declining at later time intervals.
Conclusions and Clinical Relevance—CLM and LDH histochemistry techniques yield different absolute numbers of live and dead cells, resulting in differing percentages of live or dead cells with each technique. These differences may be related to the enzymes responsible for activation in each technique and the susceptibility of these enzymes to thermal injury. Results of TUNEL indicate that apoptosis contributes to chondrocyte death after thermal injury, with a peak signal identified 3 days after insult.
Objective—To determine the critical temperature that reduces chondrocyte viability and evaluate the ability of chondrocytes to recover after exposure to the critical temperature.
Sample Population—Cartilage explants obtained from the humeral heads of 30 sheep.
Procedures—In a randomized block design, 318 full-thickness cartilage explants were collected from 30 humeral heads of sheep and cultured for up to 14 days. On the first day of culture (day 0), explants were subjected to temperatures of 37°, 45°, 50°, 55°, 60°, or 65°C for 5 minutes by heating culture tubes in a warming block. The ability for chondrocytes to recover after exposure to the critical temperature was determined by evaluating viability at days 0, 1, 3, 7, and 14 days after heating. Images were analyzed by use of confocal laser microscopy.
Results—Analysis of images revealed a significant decrease in live cells and a significant increase in dead cells as temperature increased. Additionally, the deepest layer of cartilage had a significantly lower percentage of live cells, compared with values for the 3 most superficial layers. Chondrocytes did have some ability to recover temporarily after the initial thermal insult.
Conclusions and Clinical Relevance—A strong relationship exists between increasing temperature and cell death, with a sharp increase in chondrocyte death between 50° and 55°C. Chondrocytes in the deepest cartilage layer are most susceptible to thermal injury. The threshold of chondrocyte recovery from thermal injury is much lower than temperatures reached during chondroplasty by use of most radiofrequency energy devices.