Comparison of Digital Radiography, Computed Tomography, and Magnetic Resonance Imaging Features in Canine Spontaneous Degenerative Stifle Joint Osteoarthritis

Canine stifle joint osteoarthritis (OA) is characterized by damage and degeneration of the articular cartilage and subchondral bone, bony hypertrophy at the margins, and synovial joint membrane changes. Non-invasive imaging modalities, such as digital radiography (DR), computed tomography (CT), and magnetic resonance imaging (MRI), can be used to describe these changes. However, the value of MRI in diagnosing spontaneous canine OA and the comparison of different imaging modalities have seldom been addressed. This study compared multiple noninvasive imaging modalities in canine spontaneous stifle OA cases. Four client-owned dogs with five spontaneously affected OA stifle joints were recruited and underwent DR, CT, and MRI. Information on osteophytes/enthesophytes, ligament/tendon lesions, synovial effusion and membrane thickening, subchondral bone lesions, and meniscal and cartilage lesions were scored and compared. The results showed that MRI provides the most comprehensive and superior lesion detection sensitivity for ligament, meniscus, cartilage, and synovial effusions. DR provides adequate bony structure information, while CT provides the most delicate images of bony structure lesions. These imaging findings may provide further understanding of the disease and help clinicians draft a more precise treatment plan.

Etiopathogenesis of Canine Cruciate Ligament Disease: A Scoping Review

The spontaneous rupture of the cranial cruciate ligament in dogs remains a pathoetiologic puzzle. Despite much progress in research over the past years, the systemic and local mechanisms leading to ligament degeneration and structural failure remain largely obscure. This scoping review focuses on pathogenesis and aims at summarizing and interpreting today's knowledge on causes of canine cruciate ligament rupture, i.e., the multifactorial mechanisms leading to degenerative stifle joint disease with collagen matrix degeneration and structural failures. Thus, the initial view of traumatic ligament rupture, fostered by "wear and tear", has clearly been replaced by a new concept of systemic processes linked to progressive degenerative joint disease and ligament failure; thus, the term "cranial cruciate ligament disease" has been coined and is generally accepted. In addition, cruciate ligament rupture in people shares some similarities with the lesion in dogs; therefore, the review also includes comparative studies. The methods used were based on the PRISMA-ScR model (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews).

Cranial cruciate ligament structure in relation to the tibial plateau slope and intercondylar notch width in dogs

Cranial cruciate ligament (CCL) rupture is one of the most common orthopedic conditions in dogs. The pathogenesis of CCL rupture is not fully described and remains to be elucidated fully. Several hypotheses have been proposed to explain the etiology of these changes. The objective of this study was to investigate structural changes in the CCL in relation to the tibial plateau angle (TPA) and the intercondylar notch (ICN) width in dogs. Fifty-five skeletally mature dogs were included in this study. ICN width and TPA measurements were obtained from intact CCL stifles. Samples of the CCL, caudal cruciate ligament (CaCL), and femoral head ligament (FHL) were harvested and stained for routine histological and immunohistochemical analysis. Microscopic changes in the ligaments were observed and were found to correlate with the TPA and ICN width values. The degree of structural changes within the CCL was observed to correlate with an increasing TPA and a narrowing ICN width. Changes in the CCL are likely to be caused by excessive forces acting through the ligament in stifles with a high TPA. Chondroid metaplasia of the CCL is an adaptation to abnormal mechanics within the stifle joint caused by altered bone morphology.

Variations in cell morphology in the canine cruciate ligament complex

Cell morphology may reflect the mechanical environment of tissues and influence tissue physiology and response to injury. Normal cruciate ligaments (CLs) from disease-free stifle joints were harvested from dog breeds with a high (Labrador retriever) and low (Greyhound) risk of cranial cruciate ligament (CCL) rupture. Antibodies against the cytoskeletal components vimentin and alpha tubulin were used to analyse cell morphology; nuclei were stained with 4',6-diamidino-2-phenylindole, and images were collected using conventional and confocal microscopy. Both cranial and caudal CLs contained cells of heterogenous morphologies. Cells were arranged between collagen bundles and frequently had cytoplasmic processes. Some of these processes were long (type A cells), others were shorter, thicker and more branched (type B cells), and some had no processes (type C cells). Processes were frequently shown to contact other cells, extending longitudinally and transversely through the CLs. Cells with longer processes had fusiform nuclei, and those with no processes had rounded nuclei and were more frequent in the mid-substance of both CLs. Cells with long processes were more commonly noted in the CLs of the Greyhound. As contact between cells may facilitate direct communication, variances in cell morphology between breeds at a differing risk of CCL rupture may reflect differences in CL physiology.

Lymphocyte populations in joint tissues from dogs with inflammatory stifle arthritis and associated degenerative cranial cruciate ligament rupture

OBJECTIVE

To evaluate lymphocyte populations in stifle synovium and synovial fluid of dogs with degenerative cranial cruciate ligament rupture (CCLR).

STUDY DESIGN

Prospective clinical study.

ANIMALS

Dogs (n=25) with stifle arthritis and CCLR, 7 dogs with arthritis associated with cartilage degeneration (osteoarthritis [OA]), and 12 healthy Beagle dogs with intact CCL.

METHODS

Arthritis was graded radiographically in CCLR dogs. After collection of joint tissues, mononuclear cells were isolated and subsequently analyzed using flow cytometry for expression of CD3, CD4, CD8, and CD21.

RESULTS

The proportions of CD4(+) T helper lymphocytes, CD8(+) cytotoxic T lymphocytes, and CD3(+) CD4(-) CD8(-) T lymphocytes were increased in synovium from dogs with CCLR compared with synovium from healthy Beagle dogs (P<.05). The proportion of CD3(+) CD4(-) CD8(-) T lymphocytes in synovial fluid was increased in dogs with CCLR compared with dogs with OA (P<.05). In dogs with CCLR, the proportion of CD3(+) CD4(-) CD8(-) T lymphocytes in synovial fluid was inversely correlated with radiographic arthritis (S(R) =-0.68, P<.005).

CONCLUSION

Lymphocytic inflammation of stifle synovium and synovial fluid is an important feature of the CCLR arthropathy. Lymphocyte populations include T lymphocytes expressing CD4 and CD8, and CD3(+) CD4(-) CD8(-) T lymphocytes. Presence of CD3(+) CD4(-) CD8(-) T lymphocytes was associated with development of stifle synovitis. Further work is needed to fully identify the phenotype of these cells.

Cranial cruciate ligament disease in dogs: biology versus biomechanics

The stifle joint of dogs is an organ comprised of multiple tissue types that must work in concert to maintain joint health and function. Cruciate disease in dogs is caused by a spectrum of causal and risk factors that result in a final common pathway of abnormal biomechanics and abnormal biology causing osteoarthritis, or organ failure, of the stifle and the clinical signs of lameness, pain, and limb dysfunction. It is vital to understand the components of the biologic and biomechanical pathologies to improve our understanding of cruciate disease in dogs so that we can improve preventative, diagnostic, and therapeutic strategies for our canine patients.