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Abstract

Objective—To determine localization of tartrate-resistant acid phosphatase (TRAP) and cathepsin K in ruptured and healthy cranial cruciate ligaments (CCL) in dogs.

Animals—30 dogs with ruptured CCL, 8 aged dogs without ruptured CCL, and 9 young dogs without ruptured CCL.

Procedure—The CCL was examined histologically and cells containing TRAP and cathepsin K were identified histochemically and immunohistochemically, respectively.

Results—Cathepsin K and TRAP were detected within the same cells, principally within the epiligamentous region and to a lesser extent in the core region of ruptured CCL. Numbers of cells containing TRAP and cathepsin K were significantly greater in ruptured CCL, compared with CCL from young or aged dogs, and numbers of such cells were greater in CCL from aged dogs, compared with those of young dogs. In aged dogs, small numbers of cells containing TRAP and cathepsin K were seen in intact CCL associated with ligament fascicles in which there was chondroid transformation of ligament fibroblasts and disruption of the extracellular matrix.

Conclusion and Clinical Relevance—Ruptured CCL contain greater numbers of cells with the proteinases TRAP and cathepsin K than CCL from healthy, young, or aged dogs. Results suggest that cell-signaling pathways that regulate expression of these proteinases may form part of the mechanism that leads to upregulation of collagenolytic ligament remodeling and progressive structural failure of the CCL over time. (Am J Vet Res 2002;63:1279–1284).

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether medullary reaming alone, or followed by cemented hemiarthroplasty, influenced porosity, vascularity, and new bone formation in the proximal portion of the femur in dogs.

Animals

12 adult mixed-breed dogs.

Procedure

Unilateral femoral head and neck excisions were performed, followed by femoral medullary reaming in 6 dogs and femoral medullary reaming and cemented hemiarthroplasty in 6 dogs; the contralateral femur was used as a control. All dogs were euthanatized 28 days after surgery, and femurs were harvested. Vascularity, porosity, and new bone formation were quantified for all femurs of dogs from both groups at 3 proximal-to-distal levels, 3 regions (periosteal, midcortical, and endosteal), and 4 quadrants (cranial, caudal, medial, and lateral) of the femur.

Results

Medullary reamed and cemented hemiarthroplasty femurs had significant increases in vascularity and porosity at all levels and in new bone formation at levels 2 and 3. Porosity was increased significantly in the periosteal region of the cemented hemiarthroplasty (9.7 ± 0.7%), compared with control (2.3 ± 0.2%) and medullary reamed (8.4 ± 0.7%) femurs. Porosity was increased in the caudal and medial quadrants in the medullary reamed and cemented hemiarthroplasty femurs; vascularity results were similar.

Conclusion

Increased porosity, vascularity, and new bone formation in reamed and cemented hemiarthroplasty-treated femurs supports the theory that surgical trauma associated with medullary reaming is an important factor in early cortical bone loss after hip arthroplasty.

Clinical Relevance

Femoral remodeling associated with reaming and broaching is appreciable but may be only a temporary response, whereas other factors may be responsible for chronic cortical bone loss. (Am J Vet Res 1999;60:922–928)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe the histomorphometric properties of epiphyseal and metaphyseal trabecular bone of the proximal portion of the femur of dogs with moderate osteoarthritis.

Sample Population—Proximal portions of a femour from 24 dogs.

Procedure—The proximal portion of a femur was obtained from each dog. Eleven and thirteen specimens were sectioned in the transverse and coronal planes, respectively. Three evenly spaced sections from each specimen were chosen, surface stained, and digitized, and the stained areas were preferentially selected. Custom software was used for histomorphometric analysis of each section. A mixed-model analysis was used to evaluate the effect of slice location and region on 6 parameters, and a Fisher protected t test was used when differences were detected.

Results—There was a significant difference between the femoral head and femoral neck for all parameters tested. In coronal sections, the femoral neck was significantly more anisotropic than the femoral head. In transverse sections, the craniolateral region of the femoral neck was significantly more anisotropic than the caudomedial and craniomedial regions.

Conclusions and Clinical Relevance—There is a predictable cancellous microarchitecture in the proximal portion of femurs from dogs with moderate osteoarthritis. Trabeculae are more numerous, thicker, and closer together but more randomly arranged in the femoral head than in the femoral neck. Dogs with moderate osteoarthritis had an increase in trabecular anisotropy in the craniolateral region of the femoral neck. However, there was no corresponding increase in trabecular alignment of the proximomedial region of the femoral head. Results support an association between trabecular alignment and the progression of osteoarthritis. ( Am J Vet Res 2005;66:150–155)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To quantify and compare the microscopic changes in articular cartilage (AC), zone of calcified cartilage (ZCC), and subchondral bone plate in femoral heads from clinically normal dogs and dogs with moderate or severe osteoarthritis.

Sample Population—Femoral heads from clinically normal dogs (n = 16) and dogs with moderate (24) or severe (14) osteoarthritis.

Procedures—Femoral heads were allocated to 3 categories (normal, moderate, or severe osteoarthritis) on the basis of radiographic findings, macroscopic findings, and histologic grade determined by use of a modified Mankin scale. Equally spaced 2-mm sections were cut in each femoral head in a coronal or transverse plane. Thickness of the AC, ZCC, and subchondral bone plate was recorded.

Results—Mean thickness of AC was significantly greater in samples with moderate and severe osteoarthritis than those considered normal. Mean thickness of the ZCC was significantly greater in samples with moderate and severe osteoarthritis than those considered normal. Mean thickness of the subchondral bone plate in samples with severe osteoarthritis was significantly greater than those with moderate osteoarthritis and those considered normal. A significant decrease in AC thickness was detected in the proximomedial area of femoral heads with severe osteoarthritis, compared with those considered normal.

Conclusions and Clinical Relevance—A cause and effect association between thickening of subchondral structures and thinning and loss of the overlying AC was not detected. Changes in AC were associated with changes in the subchondral bone plate, which is compatible with the theory of adaptation in response to altered load distribution.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare long-term outcomes of juvenile pubic symphysiodesis (JPS) and triple pelvic osteotomy (TPO) in dogs with hip dysplasia.

Design—Prospective clinical trial.

Animals—18 dogs with hip dysplasia (ie, distraction index ≥ 0.5 in at least 1 hip joint and no, mild, or moderate radiographic evidence of degenerative joint disease [DJD]).

Procedures—Dogs between 4 and 5.5 months old at enrollment were assigned to undergo JPS, and dogs between 5 and 12 months old were assigned to undergo TPO. All dogs were reexamined at 2 years of age.

Results—At 2 years of age, there were no significant differences between groups in regard to lameness scores, angle of extension of the hip joints, distraction index, peak vertical force, acetabular angle, radiographic DJD score, or owner-assigned scores of clinical function. Dorsal acetabular rim angle was significantly higher in dogs that underwent JPS than in dogs that underwent TPO. For dogs that underwent TPO, dorsal acetabular rim angle was significantly decreased and acetabular angle was significantly increased at 2 years of age, compared with values obtained prior to surgery.

Conclusions and Clinical Relevance—Results suggest that JPS and TPO have similar effects on hip joint conformation in dogs with moderate to severe hip dysplasia but that neither procedure eliminates the hip joint laxity characteristic of hip dysplasia or the progression of degenerative changes.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe cancellous architecture of the proximal portion of the femur in dogs with osteoarthritis.

Animals—30 dogs with coxofemoral osteoarthritis.

Procedure—All dogs had femoral head and neck excision or total hip arthroplasty. Histomorphometry software was used to analyze computer images of 100- μm-thick coronal and transverse plane sections of the head and neck of the femur. Histologic preparations of coronal and transverse sections of articular cartilage were graded.

Results—Bone volume/total volume, trabecular thickness, trabecular number, and bone surface/total volume were significantly higher in the femoral head than femoral neck. Trabecular alignment (anisotropy) and separation were significantly higher in the femoral neck than femoral head. Anisotropy was significantly increased in the medial portion of the femoral head in the coronal plane and in the cranial portion of the femoral neck in the transverse plane, compared with healthy dogs. The medial half of femoral head cartilage that overlies the proximomedial cancellous bone region had significantly more degraded cartilage than the lateral half. Histologic grades for cranial and caudal halves of femoral head articular cartilage were similar.

Conclusions and Clinical Relevance—Most findings were similar to those in healthy dogs. Greater trabecular alignment in the proximomedial region of the femoral head and craniolateral region of the femoral neck in dogs with osteoarthritis suggests an altered transfer of load through the coxofemoral joint. Greater cartilage degradation on the medial half of the femoral head supports an association between increased trabecular alignment and cartilage degradation. (Am J Vet Res 2000;61:1267–1272)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To describe the cancellous bone architecture of the head and neck of the femur in healthy dogs by use of automated histomorphometry techniques in conjunction with histologic grading of articular cartilage.

Animals—30 mature male dogs with healthy coxofemoral joints

Procedure—Dogs were 1.5 to 4 years old and weighed 27 to 37 kg. Computer images of fine-detail radiographs of 100-µm-thick coronal and transverse plane sections of the head and neck of the femur (14 dogs) were analyzed by use of histomorphometry software. Statistical comparisons among histomorphometric indices of 4 regions were performed. Histologic preparations of coronal and transverse plane sections of femoral head articular cartilage (16 dogs) were graded. Median grades for lateral, medial, cranial, and caudal halves of the femoral head articular cartilage were determined.

Results—Bone volume/total volume, trabecular thickness and number, and bone surface/total volume were significantly higher in the femoral head than in the femoral neck. Anisotropy (trabecular alignment) and trabecular separation were significantly higher in the femoral neck than in the femoral head. Anisotropy was significantly higher in the caudal half of the femoral neck than in the cranial half. Cartilage had histologic grades indicating health without significant differences among lateral, medial, cranial, and caudal halves of femoral head cartilage.

Conclusions and Clinical Relevance—A predictable cancellous architecture in the head and neck of the femur is associated with healthy cartilage. (Am J Vet Res 2000;61:268–274)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine fibroblast viability, assess development of apoptosis, and evaluate tissue hypoxia via histochemical, in-situ hybridization, or immunohistochemical staining in ruptured and intact cranial cruciate ligaments (CCLs) of dogs.

Animals—32 dogs with ruptured CCLs, and 8 aged and 19 young dogs with intact CCLs.

Procedure—Markers of cell viability (lactate dehydrogenase [LDH]), apoptosis (terminal deoxynucleatidyl transferase-mediated deoxyuridine triphosphate-nick end labeling [TUNEL] method), and hypoxia (hypoxiainducible factor-1α [HIF-1α] monoclonal antibody) were applied to CCL specimens; positive cells were assessed objectively (LDH) and subjectively (TUNEL and HIF-1α) in the main axial tissue component (core) and synovial intima and subintima (epiligamentous tissue).

Results—Viable fibroblasts were seen in all intact and ruptured CCLs. More nonviable cells were found in the core regions of ruptured CCLs and intact CCLs of young dogs than in the epiligamentous regions. Number of nonviable cells in the core region of ruptured CCLs was greater than that in intact CCLs of young and aged dogs, whereas the number in the epiligamentous region was similar in all specimens. The TUNEL and HIF-1αstaining was only found in the epiligamentous region of ruptured CCLs.

Conclusions and Clinical Relevance—Ruptured CCLs contained a high number of nonviable cells but not a great number of apoptotic cells. Repair processes in the epiligamentous region of the CCL include a metabolic response to hypoxia, suggesting that necrosis of ligament fibroblasts and transformation of surviving cells to a spheroid phenotype may be a response to hypoxia cause by microinjury or inadequate blood flow. (Am J Vet Res 2003;64:1010–1016)

Full access
in American Journal of Veterinary Research