Data from: Genome-wide association analysis in dogs implicates 99 loci as risk variants for anterior cruciate ligament rupture

Anterior cruciate ligament (ACL) rupture is common condition that can be devastating and life changing, particularly in young adults. A non-contact mechanism is typical. Second ACL ruptures through rupture of the contralateral ACL or rupture of a graft repair is also common. Risk of rupture is increased in females. ACL rupture is also common in dogs. Disease prevalence exceeds 5% in several dog breeds, ~100 fold higher than human beings. We provide insight into the genetic etiology of ACL rupture by genome-wide association study (GWAS) in a high-risk breed using 98 case and 139 control Labrador Retrievers. We identified 129 single nucleotide polymorphisms (SNPs) within 99 risk loci. Associated loci (P<5.0E-04) explained approximately half of phenotypic variance in the ACL rupture trait. Two of these loci were located in uncharacterized or non-coding regions of the genome. A chromosome 24 locus containing nine genes with diverse functions met genome-wide significance (P=3.63E-0.6). GWAS pathways were enriched for c-type lectins, a gene set that includes aggrecan, and a gene set encoding membrane transport proteins with a variety of physiological functions. Genotypic risk estimated for each dog based on the risk contributed by each GWAS locus showed clear separation of ACL rupture cases and controls. Power analysis of the GWAS data set estimated that ~172 loci explain the genetic contribution to ACL rupture in the Labrador Retriever. Heritability was estimated at 0.48. We conclude ACL rupture is a moderately heritable highly polygenic complex trait. Our results implicate c-type lectin pathways in ACL homeostasis

Use of a platelet-rich plasma-collagen scaffold as a bioenhanced repair treatment for management of partial cruciate ligament rupture in dogs

<div><p>Dogs are commonly affected with cruciate ligament rupture (CR) and associated osteoarthritis (OA), and frequently develop a second contralateral CR. Platelet rich plasma (PRP) is a component of whole blood that contains numerous growth factors, which in combination with a collagen scaffold may act to promote bioenhanced primary repair of ligament. This study tested the hypothesis that treatment of partial stable CR stifles with an intra-articular collagen scaffold and PRP would decrease the disease progression, synovitis and risk of complete CR over a 12-month study period. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. All dogs were treated with tibial plateau leveling osteotomy (TPLO) on the unstable stifle and a single intra-articular application of PRP-collagen in the stable partial CR stifle. Dogs were evaluated at the time of diagnosis, and at 10-weeks and 12-months after treatment. We evaluated correlation between both development of complete CR and time to complete CR with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla magnetic resonance (MR) imaging, and bilateral stifle arthroscopy. Additionally, histologic evaluation of synovial biopsies, C-reactive protein (CRP) concentrations in serum and synovial fluid, and synovial total nucleated cell count, were determined. Results indicated that a single application of PRP-collagen in partial CR stifles of client owned dogs is not an effective disease-modifying therapy for the prevention of progression to complete CR. Radiographic effusion, arthroscopic evaluation of cranial cruciate ligament (CrCL) damage, and MR assessment of ligament fiber tearing in partial CR stifles correlated with progression to complete CR over the 12-month follow-up period. We determined that the best predictive model for development of complete CR in PRP-collagen treated partial CR stifles included variables from multiple diagnostic modalities.</p></div

Radiographic and magnetic resonance imaging predicts severity of cruciate ligament fiber damage and synovitis in dogs with cranial cruciate ligament rupture

<div><p>Cruciate ligament rupture (CR) and associated osteoarthritis (OA) is a common condition in dogs. Dogs frequently develop a second contralateral CR. This study tested the hypothesis that the degree of stifle synovitis and cranial cruciate ligament (CrCL) matrix damage in dogs with CR is correlated with non-invasive diagnostic tests, including magnetic resonance (MR) imaging. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. We evaluated correlation of stifle synovitis and CrCL fiber damage with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla MR imaging, and bilateral stifle arthroscopy. Histologic grading and immunohistochemical staining for CD3⁺ T lymphocytes, TRAP⁺ activated macrophages and Factor VIII⁺ blood vessels in bilateral stifle synovial biopsies were also performed. Serum and synovial fluid concentrations of C-reactive protein (CRP) and carboxy-terminal telopeptide of type I collagen (ICTP), and synovial total nucleated cell count were determined. Synovitis was increased in complete CR stifles relative to partial CR stifles (<i>P</i><0.0001), although total nucleated cell count in synovial fluid was increased in partial CR stifles (<i>P</i><0.01). In partial CR stifles, we found that 3D Fast Spin Echo Cube CrCL signal intensity was correlated with histologic synovitis (S_R = 0.50, <i>P</i><0.01) and that radiographic OA was correlated with CrCL fiber damage assessed arthroscopically (S_R = 0.61, <i>P</i><0.001). Taken together, results of this study show that clinical diagnostic tests predict severity of stifle synovitis and cruciate ligament matrix damage in stable partial CR stifles. These data support use of client-owned dogs with unilateral complete CR and contralateral partial CR as a clinical trial model for investigation of disease-modifying therapy for partial CR.</p></div

Changes in estimated total nucleated cell counts over time.

<p>Estimated TNCC from the synovium of <b>(A)</b> PRP-collagen treated partial CR stifles and <b>(B)</b> TPLO-treated complete CR stifles did not significantly change over the study period. <b>Abbreviations</b>: TNCC, total nucleated cell count; CR, cruciate rupture; PRP, platelet rich plasma; TPLO, tibial plateau leveling osteotomy. n = 19 dogs.</p

MRI variables from PRP-collagen treated stifles with partial cruciate ligament rupture.

<p>MRI variables from PRP-collagen treated stifles with partial cruciate ligament rupture.</p

Relationships between diagnostic variables in complete and partial cruciate rupture stifles to evaluate patterns of correlation between markers.

<p>(A) In the complete CR stifle, correlations formed three clusters. Several inflammation markers were positively correlated with Synovial and Serum CRP concentrations, suggesting that inflammation promotes collagen degradation within affected stifles. Serum CRP was also positively correlated with histologic inflammation. In a second cluster, Radiographic effusion and OA were positively correlated with arthroscopic synovitis variables. In a third cluster, numbers of CD3⁺ lymphocytes were positively correlated with numbers of TRAP⁺ macrophages and neutrophils. (B) In the partial CR stifle, a larger number of positive correlations were identified that formed four clusters. Suppurative inflammation was positively correlated with CrCL ligament volume, assessed by MR imaging, and functional length of the ligament, suggesting that acute inflammation is related to ligament edema and loss of mechanical properties. In a second cluster, synovial and serum CRP concentrations were correlated with stifle TNCC, indicating that biochemical markers of inflammation correlate with inflammatory cell counts. In a third cluster, the synovial to serum CRP ratio was positively correlated several histologic markers of inflammation, suggesting that the synovial to serum CRP ratio is likely a clinically useful marker of stifle synovitis. In a fourth cluster, arthroscopic variables of inflammation were correlated with MR imaging measures of ligament fluid content, as measured by grayscale value, suggesting that early in the CR condition, synovitis may result in increased ligament fluid content. <b>Abbreviations</b>: <b>TAS</b>, Total Arthroscopic Score; <b>ACVAS</b>, Arthroscopic CrCL Fiber Damage Visual Analog Scale (VAS) score; <b>AVAS</b>, Arthroscopic Synovitis VAS score; <b>CD3</b>, CD3⁺ T Lymphocyte Grade; <b>CrCLD</b>, Radiographic length of CrCL normalized to patellar length; <b>CRPR</b>, C-reactive Protein (CRP) serum to synovial fluid ratio; <b>FSEG</b>, MR imaging CrCL FSE Grayscale; <b>FSEV</b>, MR imaging CrCL FSE Volume; <b>FVIII</b>, Synovial Factor VIII⁺ Vessel Grade; <b>FVIIIVAS</b>, Synovial Factor VIII⁺ Vessel VAS; <b>Hgrade</b>, Histologic Synovitis Grade; <b>HVAS</b>, Histologic Synovitis VAS Score; <b>ICTPR</b>, pyridinoline cross-lined carboxy-terminal telopeptide of type I collagen (ICTP) serum to synovial fluid ratio; <b>JCRP</b>, Synovial fluid CRP; <b>JICTP</b>, Synovial fluid ICTP; <b>RADE</b>, Radiographic Effusion score; <b>RADOA</b>, Radiographic OA score; <b>SCRP</b>, Serum C-Reactive Protein; <b>SICTP</b>, Serum ICTP; <b>Supp</b>, Suppurative Inflammation Grade; <b>T1</b>, MR imaging CrCL T1 Enhancement; <b>TNCC</b>, Synovial fluid total nucleated cell count; <b>TPA</b>, Tibial Plateau Angle; <b>TRAP</b>, TRAP⁺ Macrophage Grade; <b>VIPRV</b>, MR imaging CrCL VIPR Volume; <b>VIPRG</b>, MR imaging CrCL VIPR Grayscale.</p

Relationship of radiographic synovial effusion and radiographic OA in partial CR stifles and rupture within 1 year of diagnosis.

<p>Relationship of radiographic synovial effusion and radiographic OA in partial CR stifles and rupture within 1 year of diagnosis.</p

Correlation between time to complete CR in the PRP-collagen treated stifles and variables obtained at the time of diagnosis.

<p>Correlation between time to complete CR in the PRP-collagen treated stifles and variables obtained at the time of diagnosis.</p