Outcomes and complications reported from a multiuser canine hip replacement registry over a 10-year period.

OBJECTIVE: To report outcomes and complications associated with total hip replacements (THR) using a multiuser canine hip registry (CHR) and owner-administered questionnaire. STUDY DESIGN: Prospective longitudinal clinical study. ANIMALS: Dogs (n = 1852). METHODS: Total hip replacement cases submitted to a CHR were reviewed. An online questionnaire including an adapted "Liverpool Osteoarthritis in Dogs" (LOAD) score was e-mailed to owners. Data were analyzed to determine associations between clinical variables and the agreement by veterinary surgeons and owners for complications. RESULTS: A group of 1329 (72%) dogs had unilateral THRs and another group of 523 (28%) dogs had bilateral THRs, resulting in 2375 THRs. Indications included hip dysplasia and osteoarthritis (n = 2028/2375, 85%). Implants were manufactured by Kyon (n = 1087, 46%), BioMedtrix CFX (n = 514, 22%), BioMedtrix hybrid (n = 264, 11%), BioMedtrix BFX (n = 221, 9%), and Helica (n = 107, 4.5%). Median veterinary surgeon and owner follow up were 1328 and 900 days respectively. Postoperative LOAD scores (21 ± 9) reported by 461 owners improved compared to preoperative scores (11 ± 9) (P < .001). Veterinary surgeons reported complications in 201/2375 (8.5%) THRs and owners in 107/461 (23%) THRs, with moderate agreement (weighted kappa = 0.44). No associations were identified between complications and weight, age, sex, or breed. BioMedtrix BFX and Helica implants were associated with increased complications (P = .031) when used for revisions of femoral head and neck excisions. CONCLUSION: Excellent outcomes, including improved canine mobility, were reported after THRs. Complications were underreported by veterinary surgeons compared to owners in this first multiuser CHR. CLINICAL SIGNIFICANCE: Canine THRs are safe, effective procedures but THR implants should be carefully selected when revising femoral head and neck excisions.

Long-term follow up of 44 cats undergoing total hip replacement: Cases from a feline hip registry (2010-2020).

OBJECTIVE: To report indications, complications, and long-term outcomes following feline total hip replacement (THR) using a client-based clinical metrology questionnaire, the Feline Musculoskeletal Pain Index (FMPI), and owner satisfaction. STUDY DESIGN: Multi-institutional retrospective cohort study. ANIMALS: Cats (n = 44) that underwent THR (n = 56). METHODS: Feline THRs submitted to a registry over a 10-year period were reviewed. The FMPI and owner satisfaction surveys were used to assess outcome. RESULTS: Forty-four cats met the inclusion criteria. Median age was 2 years (range: 0.9-11), and median bodyweight 5 kg (range: 3.3-7.6). British Shorthair and Domestic Shorthair were the most frequent breeds. Most cats were neutered males (33/44) and slipped capital femoral epiphysis (SCFE) was the most common surgical indication (34/56). All implants were cemented micro and nano hip implants. Overall complications (11/56) included 9 major complications. The median duration of follow up was 752 days (range: 102-3089). No association was found between clinical variables and complications. The FMPI score improved from 0.111 (range: 0-1.222) to 2.111 (range: 0.888-3.666) postoperatively (P < .001). Owner satisfaction was reported as "very good" in 30/33 cases (90.9%). CONCLUSION: A validated client metrology questionnaire showed clinical improvement in cats following THR. The most common indication for THR in cats was SCFE occurring in young male neutered cats. Complication rates were comparable to previous reports. CLINICAL SIGNIFICANCE: Total hip replacement appears to be a successful surgical treatment for feline hip disease with very good owner satisfaction and acceptable complication rates.

Multiomics analysis of the mdx/mTR mouse model of Duchenne muscular dystrophy.

PURPOSE/AIM: Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease characterized by extensive muscle weakness. Patients with DMD lack a functional dystrophin protein, which transmits force and organizes the cytoskeleton of skeletal muscle. Multiomic studies have been proposed as a way to obtain novel insight about disease processes from preclinical models, and we used this approach to study pathological changes in dystrophic muscles. MATERIALS AND METHODS: We evaluated hindlimb muscles of male mdx/mTR mice, which lack a functional dystrophin protein and have deficits in satellite cell abundance and proliferative capacity. Wild type (WT) C57BL/6 J mice served as controls. Muscle fiber contractility was measured, along with changes in the transcriptome using RNA sequencing, and in the proteome, metabolome, and lipidome using mass spectrometry. RESULTS: While mdx/mTR mice displayed gross pathological changes and continued cycles of degeneration and regeneration, we found no differences in permeabilized fiber contractility between strains. However, there were numerous changes in the transcriptome and proteome related to protein balance, contractile elements, extracellular matrix, and metabolism. There was only a 53% agreement in fold-change data between the proteome and transcriptome. Numerous changes in markers of skeletal muscle metabolism were observed, with dystrophic muscles exhibiting elevated glycolytic metabolites such as 6-phosphoglycerate, fructose-6-phosphate and glucose-6-phosphate, fructose bisphosphate, phosphorylated hexoses, and phosphoenolpyruvate. CONCLUSIONS: These findings highlight the utility of multiomics in studying muscle disease, and provide additional insight into the pathological changes in dystrophic muscles that might help to indirectly guide evidence-based nutritional or exercise prescription in DMD patients.

The effect of exercise on the protein profile of rat knee joint intra- and extra-articular ligaments.

Injuries to the intra-articular anterior cruciate ligament (ACL) and the extra-articular medial collateral ligament (MCL) result in significant knee joint instability, pain, and immobility. Moderate endurance-type exercise can increase ligament strength but little is known on the effect of short-term regular bouts of high-intensity exercise on the extracellular matrix (ECM) structure of knee ligaments. Therefore, this study aimed to identify the effect of short-term regular bouts high exercise on the proteome of the rat ACL and MCL using mass spectrometry. Sprague-Dawley male rats (n = 6) were split into control and exercise groups, and subjected to high-intensity training for four 4 weeks followed by proteomic analyses of the ACL and MCL. Knee joint health status was assessed using OARSI and a validated histological scoring system. Histopathological analyses demonstrated no significant changes in either in cruciate, collateral ligaments, or cartilage between the control and exercised knee joints. However, significant proteins were found to be more abundant in the exercised ACL compared to ACL control group but not between the exercised MCL and control MCL groups. The significant abundant proteins in ACL exercise groups were mostly cytoskeletal, ribosomal and enzymes with several abundant matrisomal proteins such as collagen proteins and proteoglycans being found in this group. In conclusion, our results indicate that short-term regular bouts of high-intensity exercise have an impact on the intra-articular ACL but not extra-articular MCL ECM protein expression.

Identification and Characterization of Canine Ligament Progenitor Cells and Their Extracellular Matrix Niche.

Ligaments are prone to injury and degeneration in humans and animals, however the healing potential of ligament is poor and current treatment options ineffective. Stem cell-based therapies hold potential for treatment of ligament injuries. This study aimed to characterize a ligament progenitor cell (LPC) population and to identify specific niche components which could promote the survival and function of LPCs. LPCs were isolated from canine cranial cruciate ligament and characterized for clonogenicity, multipotency and marker expression. The extracellular matrix (ECM) composition was characterized by the novel application of a metabolic labeling and mass spectrometry technique. LPCs demonstrated clonogenicity, multipotency, and stem cell marker expression. A number of different collagens, glycoproteins, and proteoglycans were identified in the LPC niche using proteomics. Metabolic labeling of cells demonstrated unique turnover profiles for distinct ECM protein groups, indicating the importance of certain niche components for LPC survival and function. The newly synthesized niche components identified in this study could be exploited to aid identification of LPCs and to promote their survival and function for potential ligament repair strategies.

Variations in internal structure, composition and protein distribution between intra- and extra-articular knee ligaments and tendons.

Tendons and ligaments play key roles in the musculoskeletal system in both man and animals. Both tissues can undergo traumatic injury, age-related degeneration and chronic disease, causing discomfort, pain and increased susceptibility to wider degenerative joint disease. To date, tendon and ligament ultrastructural biology is relatively under-studied in healthy, non-diseased tissues. This information is essential to understand the pathology of these tissues with regard to function-related injury and to assist with the future development of tissue-engineered tendon and ligament structures. This study investigated the morphological, compositional and extracellular matrix protein distribution differences between tendons and ligaments around the non-diseased canine stifle joint. The morphological, structural characteristics of different regions of the periarticular tendons and ligaments (the intra-articular anterior cruciate ligament, the extra-articular medial collateral ligament, the positional long digital extensor tendon and energy-storing superficial digital flexor tendons) were identified using a novel semi-objective histological scoring analysis and by determining their biochemical composition. Protein distribution of extracellular matrix collagens, proteoglycans and elastic fibre proteins in anterior cruciate ligament and long digital extensor tendon were also determined using immunostaining techniques. The anterior cruciate ligament was found to have significant morphological differences in comparison with the other three tissues, including less compact collagen architecture, differences in cell nuclei phenotype and increased glycosaminoglycan and elastin content. Intra- and interobserver differences of histology scoring resulted in an average score 0.7, indicative of good agreement between observers. Statistically significant differences were also found in the extracellular matrix composition in terms of glycosaminoglycan and elastin content, being more prominent in the anterior cruciate ligament than in the other three tissues. A different distribution of several extracellular matrix proteins was also found between long digital extensor tendon and anterior cruciate ligament, with a significantly increased immunostaining of aggrecan and versican in the anterior cruciate ligament. These findings directly relate to the different functions of tendon and ligament and indicate that the intra-articular anterior cruciate ligament is subjected to more compressive forces, reflecting an adaptive response to normal or increased loads and resulting in different extracellular matrix composition and arrangement to protect the tissue from damage.

A comparison of the stem cell characteristics of murine tenocytes and tendon-derived stem cells.

Tendon is a commonly injured soft musculoskeletal tissue, however, poor healing potential and ineffective treatment strategies result in persistent injuries and tissue that is unable to perform its normal physiological function. The identification of a stem cell population within tendon tissue holds therapeutic potential for treatment of tendon injuries. This study aimed, for the first time, to characterise and compare tenocyte and tendon-derived stem cell (TDSC) populations in murine tendon. Tenocytes and TDSCs were isolated from murine tail tendon. The cells were characterised for morphology, clonogenicity, proliferation, stem cell and tenogenic marker expression and multipotency. TDSCs demonstrated a rounded morphology, compared with a more fibroblastic morphology for tenocytes. Tenocytes had greater clonogenic potential and a smaller population doubling time compared with TDSCs. Stem cell and early tenogenic markers were more highly expressed in TDSCs, whereas late tenogenic markers were more highly expressed in tenocytes. Multipotency was increased in TDSCs with the presence of adipogenic differentiation which was absent in tenocytes. The differences in morphology, clonogenicity, stem cell marker expression and multipotency observed between tenocytes and TDSCs indicate that at least two cell populations are present in murine tail tendon. Determination of the most effective cell population for tendon repair is required in future studies, which in turn may aid in tendon repair strategies.

Comparison between chaotropic and detergent-based sample preparation workflow in tendon for mass spectrometry analysis.

Exploring the tendon proteome is a challenging but important task for understanding the mechanisms of physiological/pathological processes during ageing and disease and for the development of new treatments. Several extraction methods have been utilised for tendon mass spectrometry, however different extraction methods have not been simultaneously compared. In the present study we compared protein extraction in tendon with two chaotropic agents, guanidine hydrochloride (GnHCl) and urea, a detergent, RapiGest™, and their combinations for shotgun mass spectrometry. An initial proteomic analysis was performed following urea, GnHCl, and RapiGest™ extraction of equine superficial digital flexor tendon (SDFT) tissue. Subsequently, another proteomic analysis was performed following extraction with GnHCl, Rapigest™, and their combinations. Between the two chaotropic agents, GnHCl extracted more proteins, whilst a greater number of proteins were solely identified after Rapigest™ extraction. Protein extraction with a combination of GnHCl followed by RapiGest™ on the insoluble pellet demonstrated, after label-free quantification, increased abundance of identified collagen proteins and low sample to sample variability. In contrast, GnHCl extraction on its own showed increased abundance of identified proteoglycans and cellular proteins. Therefore, the selection of protein extraction method for tendon tissue for mass spectrometry analysis should reflect the focus of the study.

Proteomic differences between native and tissue-engineered tendon and ligament.

Tendons and ligaments (T/Ls) play key roles in the musculoskeletal system, but they are susceptible to traumatic or age-related rupture, leading to severe morbidity as well as increased susceptibility to degenerative joint diseases such as osteoarthritis. Tissue engineering represents an attractive therapeutic approach to treating T/L injury but it is hampered by our poor understanding of the defining characteristics of the two tissues. The present study aimed to determine differences in the proteomic profile between native T/Ls and tissue engineered (TE) T/L constructs. The canine long digital extensor tendon and anterior cruciate ligament were analyzed along with 3D TE fibrin-based constructs created from their cells. Native tendon and ligament differed in their content of key structural proteins, with the ligament being more abundant in fibrocartilaginous proteins. 3D T/L TE constructs contained less extracellular matrix (ECM) proteins and had a greater proportion of cellular-associated proteins than native tissue, corresponding to their low collagen and high DNA content. Constructs were able to recapitulate native T/L tissue characteristics particularly with regard to ECM proteins. However, 3D T/L TE constructs had similar ECM and cellular protein compositions indicating that cell source may not be an important factor for T/L tissue engineering.

Peak Vertical Force and Vertical Impulse in Dogs With Cranial Cruciate Ligament Rupture and Meniscal Injury.

OBJECTIVE: To compare the peak vertical force (PVF) and vertical impulse (VI) in dogs with naturally occurring cranial cruciate ligament (CCL) disease with or without concurrent meniscal injury. STUDY DESIGN: Prospective case series. STUDY POPULATION: Client-owned dogs with naturally occurring CCL disease. METHODS: Dogs with hind limb lameness because of CCL disease that required surgery underwent force plate gait analysis. Force plate analysis was performed at a walking gait (speed 1-1.3 m/s; acceleration ± 0.5 m/s(2)) and data were analyzed using commercial proprietary software. Meniscal injury was diagnosed either by mini-arthrotomy or arthroscopy. The primary outcome was PVF and the secondary outcome was VI. Comparisons were made between dogs with or without meniscal injury, and dogs with partial or complete CCL rupture. RESULTS: Forty dogs were included. Meniscal injury was present in 18/40 dogs (45%). PVF (P = .003) and VI (P = .01) were significantly lower in dogs with meniscal injury than in dogs without meniscal injury. CONCLUSION: Dogs with CCL disease and medial meniscal injury had significantly reduced PVF and VI.

Ultrasonographic monitoring of feline epaxial muscle height as part of an annual wellness examination to assess for the development of sarcopenia.

OBJECTIVES: The aim of this study was to determine if epaxial muscle height (EMH) could be reliably incorporated into annual routine wellness screenings, and also determine its relationship to age, body condition score (BCS), subjective muscle assessment (SMA), breed and sex in mature cats. METHODS: EMH was determined independently by three observers from ultrasonographic examinations - collected by an additional trained individual - of cats enrolled at the Feline Healthy Ageing Clinic, University of Liverpool, UK. Age, body weight, BCS and SMA data were also collected. RESULTS: A total of 92 cats were included, 35 of which had repeat ultrasonographic examinations 12 months apart. Enrolled cats were a median age of 8 years and 9 months at the time of the first measurement. Variation in the quality of ultrasonographic images collected did not affect muscle depth measurements (P = 0.974). Further, there was good intra- and inter-observer repeatability for all observations (intraclass correlation range 0.97-0.99). There was a moderate positive association between EMH and body weight (r = 0.49, P <0.001) but no association with age (r = -0.05, P = 0.680). There were also positive associations in EMH among cats with different BCSs (P = 0.001) and SMAs (thoracic spine, P = 0.021; lumbar spine, P = 0.014), but breed (P = 0.429) and sex (P = 0.187) had no effect. Finally, there was no change in EMH measurements in the paired samples (P = 0.145) or correlation between percentage weight and EMH change over 12 months. CONCLUSIONS AND RELEVANCE: The accuracy of EMH measurement using ultrasonographic imaging is good, irrespective of observer experience and provided that the ultrasonographer has some training. This suggests that ultrasonographic measurement of EMH could have a major practical impact as a non-invasive determination of muscle mass in pet cat populations. Further research is required to assess longitudinal changes in muscle mass over time in senior pet cats.

Recall Bias in Client-Reported Outcomes in Canine Orthopaedic Patients Using Clinical Metrology Instruments.

OBJECTIVE: The aim of this study was to determine the accuracy of client recollection of their dogs' preconsultation status using clinical metrology instruments such as the Liverpool Osteoarthritis in Dogs (LOAD) and Canine Brief Pain Inventory (CBPI) questionnaires in dogs presenting to a referral orthopaedic clinic. STUDY DESIGN: This is a longitudinal prospective cohort study of client-owned dogs presenting for investigations of lameness (n = 217). LOAD and CBPI questionnaires were completed by the owners at the first consultation (T0). Owners were contacted at 2 (T1), 6 (T2), and 12 (T3) months and asked to recall their dogs' T0 status by completing another LOAD and CBPI questionnaire. The agreement between the T0 and recalled LOAD and CBPI scores was determined using the two-way mixed effects intraclass correlation coefficient (ICC). The Wilcoxon signed-rank test was used to determine the difference between scores. RESULTS: For the LOAD scores, there was moderate agreement between T0 and T1 (ICC: 0.64) and T0 and T2 (ICC: 0.53) scores and poor agreement between T0 and T3 (ICC: 0.496). For the CBPI Pain Severity Scores, there was poor agreement between T0 and all three subsequent time points (ICC < 0.5). For the CBPI Pain Interference Scores, there was moderate agreement between T0 and T1 (ICC: 0.57) and T2 (ICC: 0.56) scores and poor agreement between T0 and T3 (ICC: 0.43). CONCLUSION: The LOAD and CBPI questionnaires are subject to recall bias. Studies reporting retrospectively acquired CMI data should be interpreted with caution.

GenPup-M: A novel validated owner-reported clinical metrology instrument for detecting early mobility changes in dogs.

OBJECTIVE: To use a previously validated veterinary clinical examination sheet, Liverpool Osteoarthritis in Dogs (LOAD) questionnaire, combined with kinetic and kinematic gait analysis in dogs with/without mobility problems to demonstrate the capacity of a novel clinical metrology instrument ("GenPup-M") to detect canine mobility impairments. DESIGN: Quantitative study. ANIMALS: 62 dogs (31 with mobility impairments and 31 without mobility impairments). PROCEDURE: The dogs' clinical history was obtained from owners and all dogs underwent a validated orthopaedic clinical examination. Mobility impairments were diagnosed in the mobility impaired group based on clinical history and orthopaedic examination. Owners were asked to complete GenPup-M along with a previously validated mobility questionnaire (Liverpool Osteoarthritis in Dogs (LOAD)) to identify construct validity. As a test of criterion validity, the correlation between instrument scores and the overall clinical examination scores, along with force-platform obtained peak vertical forces (PVF) were calculated. GenPup-M underwent internal consistency and factor analysis. Spatiotemporal parameters were calculated for dogs with/without mobility impairments to define the gait differences between these two groups. RESULTS: Principal Component Analysis identified GenPup-M had two components with Eigenvalues >1 ("stiffness/ease of movement" and "willingness to be active/exercise"). Cronbach's α was used to test internal consistency of GenPup-M and was found to be "good" (0.87). There was a strong, positive correlation between GenPup-M and LOAD responses (r2 = 0.69, p<0.001) highlighting construct validity. Criterion validity was also shown when comparing GenPup-M to clinical examination scores (r2 = 0.74, p<0.001) and PVF (r2 = 0.43, p<0.001). Quantitative canine gait analysis showed that there were statistically significant differences between peak vertical forces (PVF) of mobility impaired and non-mobility impaired dogs (p<0.05). Analyses of PVF showed that non-mobility impaired dogs more evenly distributed their weight across all thoracic and pelvic limbs when compared to mobility impaired dogs. There were also consistent findings that mobility impaired dogs moved slower than non-mobility impaired dogs. CONCLUSION AND CLINICAL RELEVANCE: GenPup-M is a clinical metrology instrument (CMI) that can be completed by dog owners to detect all mobility impairments, including those that are early in onset, indicating the versatility of GenPup-M to assess dogs with and without mobility impairments. Results of the study found that GenPup-M positively correlated with all three objective measures of canine mobility and consequently showed criterion and construct validity. Owner-reported CMIs such as GenPup-M allow non-invasive scoring systems which veterinary surgeons and owners can use to allow communication and longitudinal assessment of a dog's mobility. It is anticipated that GenPup-M will be used by owners at yearly vaccinations/health checks, allowing identification of any subtle mobility changes, and enabling early intervention.

Small RNA signatures of the anterior cruciate ligament from patients with knee joint osteoarthritis.

Introduction: The anterior cruciate ligament (ACL) is susceptible to degeneration, resulting in joint pain, reduced mobility, and osteoarthritis development. There is currently a paucity of knowledge on how anterior cruciate ligament degeneration and disease leads to osteoarthritis. Small non-coding RNAs (sncRNAs), such as microRNAs and small nucleolar RNA (snoRNA), have diverse roles, including regulation of gene expression. Methods: We profiled the sncRNAs of diseased osteoarthritic ACLs to provide novel insights into osteoarthritis development. Small RNA sequencing from the ACLs of non- or end-stage human osteoarthritic knee joints was performed. Significantly differentially expressed sncRNAs were defined, and bioinformatics analysis was undertaken. Results and Discussion: A total of 184 sncRNAs were differentially expressed: 68 small nucleolar RNAs, 26 small nuclear RNAs (snRNAs), and 90 microRNAs. We identified both novel and recognized (miR-206, -365, and -29b and -29c) osteoarthritis-related microRNAs and other sncRNAs (including SNORD72, SNORD113, and SNORD114). Significant pathway enrichment of differentially expressed miRNAs includes differentiation of the muscle, inflammation, proliferation of chondrocytes, and fibrosis. Putative mRNAs of the microRNA target genes were associated with the canonical pathways "hepatic fibrosis signaling" and "osteoarthritis." The establishing sncRNA signatures of ACL disease during osteoarthritis could serve as novel biomarkers and potential therapeutic targets in ACL degeneration and osteoarthritis development.

Proteoglycans play a role in the viscoelastic behaviour of the canine cranial cruciate ligament.

Proteoglycans (PGs) are minor extracellular matrix proteins, and their contributions to the mechanobiology of complex ligaments such as the cranial cruciate ligament (CCL) have not been determined to date. The CCLs are highly susceptible to injuries, and their extracellular matrix comprises higher PGs content than the other major knee ligaments. Hence these characteristics make CCLs an ideal specimen to use as a model in this study. This study addressed the hypothesis that PGs play a vital role in CCL mechanobiology by determining the biomechanical behaviour at low strain rates before and after altering PGs content. For the first time, this study qualitatively investigated the contribution of PGs to key viscoelastic characteristics, including strain rate dependency, hysteresis, creep and stress relaxation, in canine CCLs. Femur-CCL-tibia specimens (n = 6 pairs) were harvested from canine knee joints and categorised into a control group, where PGs were not depleted, and a treated group, where PGs were depleted. Specimens were preconditioned and cyclically loaded to 9.9 N at 0.1, 1 and 10%/min strain rates, followed by creep and stress relaxation tests. Low tensile loads were applied to focus on the toe-region of the stress-strain curves where the non-collagenous extracellular matrix components take significant effect. Biochemical assays were performed on the CCLs to determine PGs and water content. The PG content was ∼19% less in the treated group than in the control group. The qualitative study showed that the stress-strain curves in the treated group were strain rate dependent, similar to the control group. The CCLs in the treated group showed stiffer characteristics than the control group. Hysteresis, creep characteristics (creep strain, creep rate and creep compliance), and stress relaxation values were reduced in the treated group compared to the control group. This study suggests that altering PGs content changes the microstructural organisation of the CCLs, including water molecule contents which can lead to changes in CCL viscoelasticity. The change in mechanical properties of the CCLs may predispose to injury and lead to knee joint osteoarthritis. Future studies should focus on quantitatively identifying the effect of PG on the mechanics of intact knee ligaments across broader demography.

Aging in Cats: Owner Observations and Clinical Finding in 206 Mature Cats at Enrolment to the Cat Prospective Aging and Welfare Study.

Two hundred and six cats, aged between 7 and 10 years, from the North-west of the UK, were enrolled in a cat aging and welfare study to determine the frequency of age-related conditions and associations with husbandry, owner observations of physical appearance, activity and behavior. This is the largest study to date of mature cats that includes data from an owner questionnaire and clinical examinations. At enrolment, owners frequently reported physical changes (53%), behavioral changes (47%), changes to eating patterns (41%), and activity changes (40%) in their mature cats. On physical examination, 45% cats were in overweight condition and 12% were obese. A heart murmur was detected in 29% cats, whilst indirect systolic blood pressure (SBP) was >160 mmHg in 5% cats. Dental disease was present in 54% cats and was associated with a matted hair coat (P = 0.01), increased sleeping (P = 0.02), absence of gray hairs (P = 0.03), and increased irritability to other pets (P = 0.04). Abnormalities were evident in 58% of cats that allowed an orthopedic examination (OE) to be performed. These cats were older than cats with a normal OE (P = 0.01), and abnormal OE findings were associated with a matted coat (P = 0.03) and increased grooming (P = 0.04). Aazotaemia was present in 10% cats, and this was associated with cats being observed to "sniff their food and then walk away" (P = 0.04). Hyperthyroidism was diagnosed in 3% cats, who were older (P = 0.02), had a leaner BCS (P = 0.02) and lesser blood creatinine concentrations (P = 0.01). Hyperthyroid cats were also more likely to have increased liver enzyme activity and increased SBP (P = <0.001) compared with non-hyperthyroid cats. Of the 176 cats where all clinical assessments were conducted, only 12% had no evidence of any disease. Clinical abnormalities are commonly identified when thorough, clinical assessments are performed in mature pet cats visiting primary care practice.

CT attenuation of the medial coronoid process is reduced in dogs with medial coronoid disease but independent of arthroscopic disease severity.

OBJECTIVE: To compare the attenuation of the medial coronoid process (MCP) in dogs with and without arthroscopically confirmed evidence of medial coronoid disease (MCD). ANIMALS: The database at our institution was searched for cases with thoracic limb lameness, diagnosed with MCD by arthroscopic examination that had CT as part of their investigation and compared with a control group of elbow joints from cadavers euthanized for reasons unrelated to MCD. A total of 84 elbow joints were included that met these criteria. PROCEDURES: Following CT, a standardized measurement of the MCP was obtained from apex to base and the mean attenuation, SD, and total area were recorded. A comparative measurement was obtained from the proximal radial cortex at the level of the nutrient foramen. Elbow joint arthroscopy was carried out using standard portals, and the modified Outerbridge score was (MOS) used to score elbow joint cartilage. Descriptive and inferential statistics were carried out using MLwiN and R. RESULTS: Attenuation of the MCP was reduced in dogs with MCD compared with those with no MCD (P < .002). No significant differences were observed in the attenuation between categories of severity (MOS). There was good inter- and intraobserver agreement between measurements (intraclass correlation coefficient = 0.89 and 0.95, respectively). CLINICAL RELEVANCE: MCP attenuation is reduced in dogs with MCD compared with dogs with no evidence of MCD. This finding may be a useful tool for early detection of MCD, but there is no relationship with arthroscopic lesion severity.

Age-related changes in microRNAs expression in cruciate ligaments of wild-stock house mice.

Cruciate ligaments (CL) of the knee joint are injured following trauma or aging. MicroRNAs (miRs) are potential therapeutic targets in musculoskeletal disorders, but there is little known about the role of miRs and their expression ligaments during aging. This study aimed to (1) identify if mice with normal physical activity, wild-stock house mice are an appropriate model to study age-related changes in the knee joint and (2) investigate the expression of miRs in aging murine cruciate ligaments. Knee joints were collected from 6 and 24 months old C57BL/6 and wild-stock house mice (Mus musculus domesticus) for ligament and cartilage (OARSI) histological analysis. Expression of miR targets in CLs was determined in 6-, 12-, 24-, and 30-month-old wild-stock house mice, followed by the analysis of predicted mRNA target genes and Ingenuity Pathway Analysis. Higher CL and knee OARSI histological scores were found in 24-month-old wild-stock house mice compared with 6- and 24-month-old C57BL/6 and 6-month-old wild-stock house mice (p < 0.05). miR-29a and miR-34a were upregulated in 30-month-old wild-stock house mice in comparison with 6-, 12-, and 24-month-old wild-stock house mice (p < 0.05). Ingenuity Pathway Analysis on miR-29a and 34a targets was associated with inflammation through interleukins, TGFß and Notch genes, and p53 signaling. Collagen type I alpha 1 chain (COL1A1) correlated negatively with both miR-29a (r = -0.35) and miR-34a (r = -0.33). The findings of this study support wild-stock house mice as an appropriate aging model for the murine knee joint. This study also indicated that miR-29a and miR-34a may be potential regulators of COL1A1 gene expression in murine CLs.

Ligament mechanics of ageing and osteoarthritic human knees.

Knee joint ligaments provide stability to the joint by preventing excessive movement. There has been no systematic effort to study the effect of OA and ageing on the mechanical properties of the four major human knee ligaments. This study aims to collate data on the material properties of the anterior (ACL) and posterior (PCL) cruciate ligaments, medial (MCL) and lateral (LCL) collateral ligaments. Bone-ligament-bone specimens from twelve cadaveric human knee joints were extracted for this study. The cadaveric knee joints were previously collected to study ageing and OA on bone and cartilage material properties; therefore, combining our previous bone and cartilage data with the new ligament data from this study will facilitate subject-specific whole-joint modelling studies. The bone-ligament-bone specimens were tested under tensile loading to failure, determining material parameters including yield and ultimate (failure) stress and strain, secant modulus, tangent modulus, and stiffness. There were significant negative correlations between age and ACL yield stress (p = 0.03), ACL failure stress (p = 0.02), PCL secant (p = 0.02) and tangent (p = 0.02) modulus, and LCL stiffness (p = 0.046). Significant negative correlations were also found between OA grades and ACL yield stress (p = 0.02) and strain (p = 0.03), and LCL failure stress (p = 0.048). However, changes in age or OA grade did not show a statistically significant correlation with the MCL tensile parameters. Due to the small sample size, the combined effect of age and the presence of OA could not be statistically derived. This research is the first to report tensile properties of the four major human knee ligaments from a diverse demographic. When combined with our previous findings on bone and cartilage for the same twelve knee cadavers, the current ligament study supports the conceptualisation of OA as a whole-joint disease that impairs the integrity of many peri-articular tissues within the knee. The subject-specific data pool consisting of the material properties of the four major knee ligaments, subchondral and trabecular bones and articular cartilage will advance knee joint finite element models.

The anterior cruciate ligament in murine post-traumatic osteoarthritis: markers and mechanics.

BACKGROUND: Knee joint injuries, common in athletes, have a high risk of developing post-traumatic osteoarthritis (PTOA). Ligaments, matrix-rich connective tissues, play important mechanical functions stabilising the knee joint, and yet their role post-trauma is not understood. Recent studies have shown that ligament extracellular matrix structure is compromised in the early stages of spontaneous osteoarthritis (OA) and PTOA, but it remains unclear how ligament matrix pathology affects ligament mechanical function. In this study, we aim to investigate both structural and mechanical changes in the anterior cruciate ligament (ACL) in a mouse model of knee trauma. METHODS: Knee joints were analysed following non-invasive mechanical loading in male C57BL/6 J mice (10-week-old). Knee joints were analysed for joint space mineralisation to evaluate OA progression, and the ACLs were assessed with histology and mechanical testing. RESULTS: Joints with PTOA had a 33-46% increase in joint space mineralisation, indicating OA progression. Post-trauma ACLs exhibited extracellular matrix modifications, including COL2 and proteoglycan deposition. Additional changes included cells expressing chondrogenic markers (SOX9 and RUNX2) expanding from the ACL tibial enthesis to the mid-substance. Viscoelastic and mechanical changes in the ACLs from post-trauma knee joints included a 20-21% decrease in tangent modulus at 2 MPa of stress, a decrease in strain rate sensitivity at higher strain rates and an increase in relaxation during stress-relaxation, but no changes to hysteresis and ultimate load to failure were observed. CONCLUSIONS: These results demonstrate that ACL pathology and viscoelastic function are compromised in the post-trauma knee joint and reveal an important role of viscoelastic mechanical properties for ligament and potentially knee joint health.