Magnetic resonance imaging and histology of ovine hip joint cartilage in two age populations: a sheep model with assumed healthy cartilage

A missed opportunity: A scoping review of the effect of sex and age on osteoarthritis using large animal models

OBJECTIVE

The objective was to critically analyze the published literature accounting for sex differences and skeletal age (open vs. closed physis) in preclinical animal models of OA, including the disaggregation of data by sex and skeletal maturity when data is generated from combined sex and/or multi-aged cohorts without proper confounding.

METHOD

A scoping literature review of PubMed, Web of Science, EMBASE, and SCOPUS was performed for studies evaluating the effect of sex and age in experimental studies and clinical trials utilizing preclinical large animal models of OA.

RESULTS

A total of 9727 papers were identified in large animal (dog, pig, sheep, goat, horse) models for preclinical OA research, of which 238 ex vivo and/or in vivo studies disclosed model type, animal species, sex, and skeletal age sufficient to analyze their effect on outcomes. Dogs, followed by pigs, sheep, and horses, were the most commonly used models. A paucity of preclinical studies evaluated the effect of sex and age in large animal models of naturally occurring or experimentally induced OA: 26 total studies reported some kind of analysis of the effects of sex or age, with 4 studies discussing the effects of sex only, 11 studies discussing the effects of age only, and 11 studies analyzing both the effects of age and sex.

CONCLUSION

Fundamental to translational research, OARSI is uniquely positioned to develop recommendations for conducting preclinical studies using large animal models of OA that consider biological mechanisms linked to sex chromosomes, skeletal age, castration, and gonadal hormones affecting OA pathophysiology and treatment response.

Current and Future Advanced Imaging Modalities for the Diagnosis of Early Osteoarthritis of the Hip

Hip osteoarthritis (OA) can be idiopathic or develop secondary to structural joint abnormalities of the hip joint (alteration of normal anatomy) and/or due to a systemic condition with joint involvement. Early osteoarthritic changes to the hip can be completely asymptomatic or may cause the development hip symptomatology without evidence of OA on radiographs. Delaying the progression of hip OA is critical due to the significant impact of this condition on the patient’s quality of life. Pre-OA of the hip is a newly established term that is often described as the development of signs and symptoms of degenerative hip disease but no radiographic evidence of OA. Advanced imaging methods can help to diagnose pre-OA of the hip in patients with hip pain and normal radiographs or aid in the surveillance of asymptomatic patients with an underlying hip diagnosis that is known to increase the risk of early OA of the hip. These methods include the delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC), quantitative magnetic resonance imaging (qMRI- T1rho, T2, and T2* relaxation time mapping), 7-Tesla MRI, computed tomography (CT), and optical coherence tomography (OCT). dGEMRIC proved to be a reliable and accurate modality though it is limited by the significant time necessary for contrast washout between scans. This disadvantage is potentially overcome by T2 weighted MRIs, which do not require contrast. 7-Tesla MRI is a promising development for enhanced imaging resolution compared to 1.5 and 3T MRIs. This technique does require additional optimization and development prior to widespread clinical use. The purpose of this review was to summarize the results of translational and clinical studies investigating the utilization of the above-mentioned imaging modalities to diagnose hip pre-OA, with special focus on recent research evaluating their implementation into clinical practice.

Cartilage and bone damage in rheumatoid arthritis

Rheumatoid arthritis (RA), which is a chronic inflammatory disease with a multifactorial aetiology, leads to partial or permanent disability in the majority of patients. It is characterised by persistent synovitis and formation of pannus, i.e. invasive synovial tissue, which ultimately leads to destruction of the cartilage, subchondral bone, and soft tissues of the affected joint. Moreover, inflammatory infiltrates in the subchondral bone, which can lead to inflammatory cysts and later erosions, play an important role in the pathogenesis of RA. These inflammatory infiltrates can be seen in magnetic resonance imaging (MRI) as bone marrow oedema (BME). BME is observed in 68-75% of patients in early stages of RA and is considered a precursor of rapid disease progression. The clinical significance of synovitis and bone marrow oedema as precursors of erosions is well established in daily practice, and synovitis, BME, cysts, hyaline cartilage defects and bone erosions can be detected by ultrasonography (US) and MRI. A less explored subject is the inflammatory and destructive potential of intra- and extra-articular fat tissue, which can also be evaluated in US and MRI. Finally, according to certain hypotheses, hyaline cartilage damage may trigger synovitis and lead to irreversible joint damage, and MRI may be used for preclinical detection of cartilage biochemical abnormalities. This review discusses the pathomechanisms that lead to articular cartilage and bone damage in RA, including erosion precursors such as synovitis and osteitis and panniculitis, as well as the role of imaging techniques employed to detect early cartilage damage and bone erosions.

Femoral osteochondroplasty can be performed effectively without the risk of avascular necrosis or femoral neck fractures in an experimental ovine FAI model

OBJECTIVE

The experimental induction of cam-type femoroacetabular impingement (FAI) in sheep is established. To tap the full potential of this ovine model, one should be able to perform a femoral osteochondroplasty safely. This study was based on previous cadaver experiments on the blood supply to the ovine femoral head and on the biomechanical strength of the proximal femur following offset creation. We hypothesized that offset creation in this ovine FAI model does not lead to (1) avascular necrosis (AVN) of the ovine femoral head or (2) iatrogenic femoral neck fractures and (3) can be performed effectively.

DESIGN

In this experimental, controlled, prospective study nine sheep underwent unilateral FAI induction through an intertrochanteric, varus osteotomy. Seventy days following FAI induction, femoral osteochondroplasty was performed. Sheep were sacrificed after another 140 days. Radiographs, computed tomography (CT) scans and MRI were acquired. Histologic samples were stained with hematoxylin-eosin. (1) The multimodal Association Research Circulation Osseous (ARCO) classification was used for assessment of AVN. (2) Femoral neck fractures were assessed with the multimodal imaging approach. (3) Pre- and postoperative (=after sacrifice) alpha angles and femoral neck diameters were compared.

RESULTS

(1) No signs for AVN according to the ARCO classification or (2) for femoral neck fractures were detected. (3) Mean alpha angles and femoral neck diameters decreased significantly (p < 0.001) superiorly by at least 30° respectively 4 mm after the offset creation.

CONCLUSIONS

Femoral osteochondroplasty can be performed effectively and without the risk of AVN or femoral neck fractures in this ovine FAI model.

Value of delayed gadolinium-enhanced magnetic resonance imaging of cartilage for the pre-operative assessment of cervical intervertebral discs

The study was performed to preoperatively assess the cartilage integrity of cervical intervertebral discs (IVDs) using Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC). Therefore, 53 cervical intervertebral discs of nine preoperative patients with neck and shoulder/arm pain scheduled for discectomy (five females, four males; mean age: 47.1 ± 8.4 years; range: 36-58 years) were included for biochemical analysis in this retrospective study. The patients underwent 3T magnetic resonance imaging (MRI) including biochemical imaging with dGEMRIC and morphological, sagittal T2 weighted (T2w) imaging. Cervical IVDs were rated using an MRI based grading system for cervical IVDs on T2w images. Region-of-interest measurements were performed in the nucleus pulposus (NP) and annulus fibrosus (AF) and a dGEMRIC index was calculated. Our results demonstrated that IVDs scheduled for discectomy showed significantly lower dGEMRIC index compared to IVDs that did not require surgical intervention in NP and AF (NP: 898.4 ± 191.9 ms vs. 1,150.3 ± 320.7 ms, p = 0.008; AF: 738.7 ± 183.8 ms vs. 984.6 ± 178.9 ms, p = 0.008). For Miyazaki score 3, the dGEMRIC indices were significantly lower in IVDs scheduled for surgery compared to non-operated discs for NP (p = 0.043) and AF (p = 0.018). In conclusion we could demonstrate that biochemical imaging with dGEMRIC is feasible in cervical IVDs. Significantly lower dGEMRIC index suggested GAG depletion in degenerated cervical IVD, scheduled for discectomy. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1824-1830, 2017.

Healthy ageing of cloned sheep

The health of cloned animals generated by somatic-cell nuclear transfer (SCNT) has been of concern since its inception; however, there are no detailed assessments of late-onset, non-communicable diseases. Here we report that SCNT has no obvious detrimental long-term health effects in a cohort of 13 cloned sheep. We perform musculoskeletal assessments, metabolic tests and blood pressure measurements in 13 aged (7–9 years old) cloned sheep, including four derived from the cell line that gave rise to Dolly. We also perform radiological examinations of all main joints, including the knees, the joint most affected by osteoarthritis in Dolly, and compare all health parameters to groups of 5-and 6-year-old sheep, and published reference ranges. Despite their advanced age, these clones are euglycaemic, insulin sensitive and normotensive. Importantly, we observe no clinical signs of degenerative joint disease apart from mild, or in one case moderate, osteoarthritis in some animals. Our study is the first to assess the long-term health outcomes of SCNT in large animals.

Since the birth of the first cloned animal, Dolly the sheep, concerns have been raised about potential long-term health consequences of cloning. Here the authors report on a cohort of 13 aged cloned sheep, including four created from the same cells as Dolly, and find they are healthy and seem to age normally.

Animal Models of Osteoarthritis: Comparisons and Key Considerations

Osteoarthritis (OA) is unquestionably one of the most important chronic health issues in humans, affecting millions of individuals and costing billions of dollars annually. Despite widespread awareness of this disease and its devastating impact, the pathogenesis of early OA is not completely understood, hampering the development of effective tools for early diagnosis and disease-modifying therapeutics. Most human tissue available for study is obtained at the time of joint replacement, when OA lesions are end stage and little can be concluded about the factors that played a role in disease development. To overcome this limitation, over the past 50 years, numerous induced and spontaneous animal models have been utilized to study disease onset and progression, as well as to test novel therapeutic interventions. Reflecting the heterogeneity of OA itself, no single "gold standard" animal model for OA exists; thus, a challenge for researchers lies in selecting the most appropriate model to answer a particular scientific question of interest. This review provides general considerations for model selection, as well as important features of species such as mouse, rat, guinea pig, sheep, goat, and horse, which researchers should be mindful of when choosing the "best" animal model for their intended purpose. Special consideration is given to key variations in pathology among species as well as recommended guidelines for reporting the histologic features of each model.

Intra-individual assessment of inflammatory severity and cartilage composition of finger joints in rheumatoid arthritis

OBJECTIVE

To intra-individually assess the association of inflammation severity and cartilage composition measured by RAMRIS synovitis sub-score and delayed gadolinium-enhanced magnetic resonance imaging of the cartilage (dGEMRIC) of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA).

METHODS

Forty-three patients with RA according to ACR/EULAR classification criteria (age 52.9 ± 14.5 years, range, 18-77 years) were included in this study. All study participants received 3-T MRI scans of the metacarpophalangeal joints of the second and third finger (MCP 2 and 3). The severity of synovitis was scored according to the RAMRIS synovitis sub-score by two readers in consensus. In the cases with identical synovitis sub-scores, two radiologists decided in consensus on the joint with more severe synovitis. Cartilage composition was assessed with dGEMRIC. To test the association of inflammation severity and cartilage damage and in order to eliminate inter-patient confounders, each patient's MCP 2 and 3 were dichotomized into the joint with more severe synovitis versus the joint with less severe synovitis for a paired Wilcoxon test of dGEMRIC value.

RESULTS

There was a significant difference of dGEMRIC value (median of difference: 47.12, CI [16.6; 62.76]) between the dichotomized MCPs (p = 0.0001). There was a significant correlation between dGEMRIC value and RAMRIS synovitis grading of the joint with more severe synovitis (r = 0.5; p < 0.05) and the joint with less severe synovitis (r = 0.33; p < 0.05).

CONCLUSIONS

Our data concur with the concept that synovitis severity is associated with cartilage damage. The local inflammatory status on a joint level correlated significantly with the extent of cartilage degradation in biochemical MRI.

Comparison of hip joint cartilage degeneration assessed by histology and ex vivo optical coherence tomography

The aim of this study is to validate optical coherence tomography (OCT) in assessing human articular cartilage by means of histological analyses. Twenty resected human femoral head specimens were evaluated with OCT and histological analysis. OCT and histological evaluation was performed according to the Bear and the Mankin criteria. OCT grades and Mankin scores (total score and sub-score structure) were correlated and intra-/inter-observer agreement for repeated OCT evaluations was tested by interclass-correlation coefficient (ICC) analysis. OCT grades and Mankin scores were correlated [Spearman correlation=0.742 (total) and 0.656 (structure), P<0.001], revealing significant differences between the histological scores in various OCT grades of cartilage degeneration (P<0.001). Intra-observer (ICC 0.930) and inter-observer (ICC 0.933) reliability was high (P<0.001). OCT appears to be reliable in the assessment of human articular cartilage. Further studies on intra-operative cartilage evaluation by OCT are necessary to substantiate its applicability in clinical routine.

Comparative study by computed radiography, histology, and scanning electron microscopy of the articular cartilage of normal goats and in chronic infection with caprine arthritis-encephalitis virus

In the northeast of Brazil, caprine arthritis-encephalitis (CAE) is one of the key reasons for herd productivity decreasing that result in considerable economic losses. A comparative study was carried out using computed radiography (CR), histological analysis (HA), and scanning electronic microscopy (SEM) of the joints of CAE infected and normal goats. Humerus head surface of positive animals presented reduced joint space, increased bone density, and signs of degenerative joint disease (DJD). The carpal joint presented no morphological alterations in CR in any of the animals studied. Tarsus joint was the most affected, characterized by severe DJD, absence of joint space, increased periarticular soft tissue density, edema, and bone sclerosis. Histological analysis showed chronic tissue lesions, complete loss of the surface zone, absence of proteoglycans in the transition and radial zones and destruction of the cartilage surface in the CAE positive animals. Analysis by SEM showed ulcerated lesions with irregular and folded patterns on the joint surface that distinguished the limits between areas of normal and affected cartilage. The morphological study of the joints of normal and CAE positive goats deepened understanding of the alteration in the tissue bioarchitecture of the most affected joints. The SEM finding sustained previous histological reports, similar to those found for rheumatoid arthritis, suggesting that the goat infected with CAE can be considered as a potential model for research in this area.

Association of changes in delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) with changes in cartilage thickness in the medial tibiofemoral compartment of the knee: a 2 year follow-up study using 3.0 T MRI

OBJECTIVE

To determine the association between changes in the delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) index over 2 years as a measure of cartilage proteoglycan concentration, with changes in cartilage thickness in the medial tibiofemoral compartment of knees in middle-aged women.

METHODS

One hundred and forty-eight women (one knee for each subject) aged ≥40 years were included. 3.0 T MR images of the knee were acquired at baseline, 1 year and 2 years. Three-dimensional (3D) spoiled gradient recalled echo (SPGR) sequences (for cartilage thickness) and 3D inversion recovery-prepared SPGR sequences after dGEMRIC were acquired. Segmentation was performed in the medial central (weight-bearing) femur and tibia to determine cartilage proteoglycan concentration and thickness. The association of change in the dGEMRIC indices between baseline and 1-year follow-up with (a) concomitant changes in cartilage thickness and (b) change in cartilage thickness between 1 and 2 years was assessed using linear regression.

RESULTS

In the whole-sample model, a decrease in dGEMRIC indices over time at the central medial femur significantly predicted an increase in cartilage thickness at both the central medial femur (p=0.008) and the medial tibia (p=0.04).

CONCLUSIONS

A decrease in dGEMRIC indices was associated with an increase in cartilage thickness in the medial compartment. Our results suggest that an increase in cartilage thickness may also be related to a decrease in proteoglycan concentration, which may represent swelling of cartilage in early stages of degeneration.