Estimation of articular cartilage properties using multivariate analysis of optical coherence tomography signal

SummaryObjectiveThe aim was to investigate the applicability of multivariate analysis of optical coherence tomography (OCT) information for determining structural integrity, composition and mechanical properties of articular cartilage.DesignEquine osteochondral samples (N = 65) were imaged with OCT, and their total attenuation and backscattering coefficients (μt and μb) were measured. Subsequently, the Mankin score, optical density (OD) describing the fixed charge density, light absorbance in amide I region (Aamide), collagen orientation, permeability, fibril network modulus (Ef) and non-fibrillar matrix modulus (Em) of the samples were determined. Partial least squares (PLS) regression model was calculated to predict tissue properties from the OCT signals of the samples.ResultsSignificant correlations between the measured and predicted mean collagen orientation (R2 = 0.75, P < 0.0001), permeability (R2 = 0.74, P < 0.0001), mean OD (R2 = 0.73, P < 0.0001), Mankin scores (R2 = 0.70, P < 0.0001), Em (R2 = 0.50, P < 0.0001), Ef (R2 = 0.42, P < 0.0001), and Aamide (R2 = 0.43, P < 0.0001) were obtained. Significant correlation was also found between μb and Ef (ρ = 0.280, P = 0.03), but not between μt and any of the determined properties of articular cartilage (P > 0.05).ConclusionMultivariate analysis of OCT signal provided good estimates for tissue structure, composition and mechanical properties. This technique may significantly enhance OCT evaluation of articular cartilage integrity, and could be applied, for example, in delineation of degenerated areas around cartilage injuries during arthroscopic repair surgery

How exercise influences equine joint homeostasis

The maintenance of joint homeostasis is integral to joint health. Knowledge of the influence of exercise on joint homeostasis is not only relevant for determining sustainable levels of equine athletic training, but also for the study of early development of osteoarthritis or cartilage repair in animal models. This review provides an overview of findings derived from in vivo studies and postmortem analyses investigating exercise effects on various joint tissue components in the horse, supplemented where appropriate with data from small animal models. The concept of joint homeostasis and possible methods to quantify this are also discussed, with special attention to the potential benefits and pitfalls of biomarker analysis in synovial fluid. The main conclusion is that biomechanical loading in the form of deliberate exercise has a major influence on the delicate homeostatic balance within the tissues constituting the diarthrodial joint and on their interactions, which is crucial for proper and durable joint function. The amount and intensity of exercise can have a lasting effect on tissue characteristics in juvenile animals, but affects joint homeostasis in mature animals and can affect the delicate balance between physiologic adaptation and development of pathology. Biomarkers in synovial fluid can be helpful in assessing joint homeostasis, but their use and interpretation require caution and are often far from straightforward

How exercise influences equine joint homeostasis

The maintenance of joint homeostasis is integral to joint health. Knowledge of the influence of exercise on joint homeostasis is not only relevant for determining sustainable levels of equine athletic training, but also for the study of early development of osteoarthritis or cartilage repair in animal models. This review provides an overview of findings derived from in vivo studies and postmortem analyses investigating exercise effects on various joint tissue components in the horse, supplemented where appropriate with data from small animal models. The concept of joint homeostasis and possible methods to quantify this are also discussed, with special attention to the potential benefits and pitfalls of biomarker analysis in synovial fluid. The main conclusion is that biomechanical loading in the form of deliberate exercise has a major influence on the delicate homeostatic balance within the tissues constituting the diarthrodial joint and on their interactions, which is crucial for proper and durable joint function. The amount and intensity of exercise can have a lasting effect on tissue characteristics in juvenile animals, but affects joint homeostasis in mature animals and can affect the delicate balance between physiologic adaptation and development of pathology. Biomarkers in synovial fluid can be helpful in assessing joint homeostasis, but their use and interpretation require caution and are often far from straightforward

Electrode positioning in the horse: towards standardisation of surface EMG measurements

Surface electromyography (sEMG) is a well-established method in human gait analysis, and its application has extended towards the equine field in the past decades. However, methodological consensus regarding electrode positioning is lacking, resulting in different user methodologies, hampering study comparison and repeatability. This study investigated the standardisation of bipolar electrode positioning to measure muscle activity in horses during dynamic contractions. Ultrasound scans were made of three muscles (Triceps Brachii caput longum (TB), Longissimus Dorsi (LD), and Semitendinosus (ST)) of six horses to determine the muscle borders and fibre direction. Linear arrays of approximately ten electrodes (4 mm diameter, 20 mm inter-electrode distance) were placed on the clipped and cleaned skin, parallel to the muscle fibre direction. The middle of the array was always placed at 50% between two anatomical landmarks chosen near (one of ) the origins and insertions of the respective muscle. Data were collected (SAGA® TMSi, 4,000 Hz) for one minute at trot on a treadmill. The root mean square (RMS) values, innervation zone (IZ) location and presence of crosstalk were determined to evaluate electrode positions. The optimal positions were at 40-49 and 32-45% between the used anatomical landmarks for TB and ST respectively. Electrodes positioned within the thoracic region of the LD recorded higher, i.e. better, RMS values compared to electrodes in the lumbar region, though results were similar regarding IZ location and presence of crosstalk. The proposed positions may serve as a standardised reference for bipolar electrode placement to measure sEMG in horses during dynamic contractions.Effect of body position on a 3-dimensional scanning assessment of muscle massA. Borer-Matsui1, G.C. Donnelly2 and S. Valberg11Michigan State University, Large Animal Clinical Sciences, 736 Wilson Rd, 48824, East Lansing MI, USA, 2University of California, Davis, Department of Population Health and Reproduction, One Shields Drive, 95616, Davis CA, USA; [email protected] performance relies on well-developed musculature which has been difficult to accurately measure. We recently devised a 3-dimensional photonic scan to capture body volume (V) as a proxy for muscle mass validated in horses with 4 hooves square, a difficult stance to achieve. The purpose of this study was to determine the effect of modest differences in body position on measurement of body V. Anatomic markers were placed on 8 horses positioned with; 4 hooves square; neck turned ⌁25°; head raised mean 17 cm; one hind hoof (HH) anterior offset ⌁15 cm; a front and opposite HH ⌁15 cm offset (n=7); one HH resting. A handheld Occipital Structure Sensor scanner connected to an iPad and Skanect and Materialise 3-Matic programs were used to capture V in specific body sectors delineated by anatomic markers. Volume of back and hindquarter sectors standing square were compared to various positions using ANOVA (

Optical coherence tomography of cartilage lesions in the equine metacarpophalangeal joint

Objective: To report the history, signalment, indication for pacing and epicardial lead placement complications and final outcome of 28 dogs and 5 cats in which permanent epicardial pacing leads were surgically placed at a single institution. Methods: Medical records of 28 dogs and 5 cats were retrospectively reviewed. Signalment, age, species, gender, clinical signs, presence of structural heart disease and/or congestive heart failure, ECG diagnosis, reason to select epicardial surgery, patient size (more or less than 14 kg), year of study period, and overall survival rate were recorded. Statistical correlations were made between those variables and rates of major and minor complications. Results: No statistical differences were found in the prevalence of major (life threatening or requiring replacement of the pacemaker system) and minor (self-limiting) complications with respect to the different variables listed above except for patient size. A significant difference in survival was found between animals that sustained major complications versus those that did not. Cox regression analysis showed that size of patient, occurrence of major complications and presence of structural heart disease negatively impacted survival rate. Clinical Relevance: The transdiaphragmatic approach may result in specific intraoperativeand short-term complications (lead dislodgment). The presence of structural heart disease at diagnosis and the occurrence of major complications are associated with a decreased survival rate. Patients weighing more than 14 kg experienced more major complications. Improvement of patient outcomes following epicardial lead placement could possibly be made by selecting a different surgical approach or by designing a different type of epicardial lead for animals

Evaluation of articular cartilage with quantitative MRI in an equine model of post-traumatic osteoarthritis.

Chondral lesions lead to degenerative changes in the surrounding cartilage tissue, increasing the risk of developing post-traumatic osteoarthritis (PTOA). This study aimed to investigate the feasibility of quantitative magnetic resonance imaging (qMRI) for evaluation of articular cartilage in PTOA. Articular explants containing surgically induced and repaired chondral lesions were obtained from the stifle joints of seven Shetland ponies (14 samples). Three age-matched nonoperated ponies served as controls (six samples). The samples were imaged at 9.4 T. The measured qMRI parameters included T(1) , T(2) , continuous-wave T(1ρ) (CWT(1ρ) ), adiabatic T(1ρ) (AdT(1ρ) ), and T(2ρ) (AdT(2ρ) ) and relaxation along a fictitious field (T(RAFF) ). For reference, cartilage equilibrium and dynamic moduli, proteoglycan content and collagen fiber orientation were determined. Mean values and profiles from full-thickness cartilage regions of interest, at increasing distances from the lesions, were used to compare experimental against control and to correlate qMRI with the references. Significant alterations were detected by qMRI parameters, including prolonged T(1) , CWT(1ρ) , and AdT(1ρ) in the regions adjacent to the lesions. The changes were confirmed by the reference methods. CWT(1ρ) was more strongly associated with the reference measurements and prolonged in the affected regions at lower spin-locking amplitudes. Moderate to strong correlations were found between all qMRI parameters and the reference parameters (ρ = -0.531 to -0.757). T(1) , low spin-lock amplitude CWT(1ρ) , and AdT(1ρ) were most responsive to changes in visually intact cartilage adjacent to the lesions. In the context of PTOA, these findings highlight the potential of T(1) , CWT(1ρ) , and AdT(1ρ) in evaluation of compositional and structural changes in cartilage