The Effect of Parentage on the Prevalence, Severity and Location of Lesions of Osteochondrosis in Swine

Epiphyseal cartilage vascular architecture at the distal humeral osteochondritis dissecans predilection site in juvenile pigs

Failure of endochondral ossification due to interruption of the vascular supply to the epiphyseal cartilage is a critical step in the development of osteochondritis dissecans (OCD). Herein we describe the vascular architecture of the distal humeral epiphyseal cartilage in pigs and identify characteristic features that have been associated with sites predisposed to OCD development across species. Distal humeral specimens were harvested from pigs (n = 5, ages = 1, 10, 18, 30, and, 42 days old) and imaged at 9.4T magnetic resonance imaging (MRI) using a 3D gradient recalled echo sequence. The MRI data were processed using a quantitative susceptibility mapping (QSM) pipeline to visualize the vascular architecture. Specimens were also evaluated histologically to identify the presence of ischemic epiphyseal cartilage necrosis (osteochondrosis [OC]-latens) and associated failure of endochondral ossification (OC-manifesta). The QSM data enabled visualization of two distinct vascular beds arising from the perichondrium at the lateral and medial aspects of the distal humeral epiphysis. Elongated vessels originating from these beds coursed axially to supply the lateral and medial thirds of epiphyseal cartilage. At 18 days of age and older, a shift from perichondrial to transosseous blood supply was noted axially, which appeared more pronounced on the lateral side. This shift coincided with histologic identification of OC-latens (30- and 42-day-old specimens) and OC-manifesta (18- and 42-day-old specimens) lesions in the corresponding regions. The vascular anatomy and its evolution at the distal humeral epiphysis closely resembles that previously reported at predilection sites of knee OCD, suggesting a shared pathophysiology between the knee and elbow joints.

Naturally occurring osteochondrosis latens lesions identified by quantitative and morphological 10.5 T MRI in pigs

Juvenile osteochondritis dissecans (JOCD) is a pediatric orthopedic disorder that involves the articular-epiphyseal cartilage complex and underlying bone. Clinical disease is often characterized by the presence of radiographically apparent osteochondral flaps and fragments. The existence of early JOCD lesions (osteochondrosis latens [OCL] and osteochondrosis manifesta [OCM]) that precede the development of osteochondral flaps and fragments is also well recognized. However, identification of naturally occurring OCL lesions (confined to cartilage) using noninvasive imaging techniques has not yet been accomplished. We hypothesized that 10.5 T magnetic resonance imaging (MRI) can identify naturally occurring OCL lesions at predilection sites in intact joints of juvenile pigs. Unilateral elbows and knees (stifles) were harvested from three pigs aged 4, 8, and 12 weeks, and scanned in a 10.5 T MRI to obtain morphological 3D DESS images, and quantitative T2 and T1ρ relaxation time maps. Areas with increased T2 and T1ρ relaxation times in the articular-epiphyseal cartilage complex were identified in 1/3 distal femora and 3/3 distal humeri and were considered suspicious for OCL or OCM lesions. Histological assessment confirmed the presence of OCL or OCM lesions at each of these sites and failed to identify additional lesions. Histological findings included necrotic vascular profiles associated with areas of chondronecrosis either confined to the epiphyseal cartilage (OCL, 4- and 8-week-old specimens) or resulting in a delay in endochondral ossification (OCM, 12-week-old specimen). Future studies with clinical MR systems (≤7 T) are needed to determine whether these MRI methods are suitable for the in vivo diagnosis of early JOCD lesions in humans.

Gross, histopathologic, microbiologic, and radiologic characterization of lesions associated with clinical lameness in a cohort of group-housed sows euthanized for lameness

Lameness in sows is reported as the most frequent cause of early culling from commercial farms and results in reduced productivity, economic losses, and a negative impact on animal welfare. Osteochondrosis was reported as the leading cause of lameness in North American sows and, although more recent European studies report infectious arthritis as the leading cause, lameness in US production facilities using group housing for gestating sows has not yet been evaluated. This study's aim was to characterize lesions associated with lameness in the appendicular musculoskeletal system of 26 sows euthanized for lameness using pathologic, radiologic, and microbiologic analyses. Of 178 total lesions, infectious lesions were most common (54%), predominated in distal limb segments (ie, at or distal to carpi and tarsi) and more often correlated with the clinically lame limb, whereas osteochondrosis and degenerative osteoarthritis predominated in proximal limb segments (ie, at or proximal to cubital and stifle joints) and rarely correlated with the clinically lame limb. The location and characteristics of infectious lesions, including mixed bacterial growth isolated from 22/22 orthopedic sites representing 19 sows with Trueperella pyogenes isolated in 16/22 (73%) of samples, suggest an etiologic component involving trauma. Radiography had a 70.6% sensitivity and 93.9% specificity for detecting infectious lesions affecting tarsocrural, antebrachiocarpal, and digital (ie, claw) regions combined. The frequency, type, and location of infectious lesions identified in this cohort of sows euthanized for lameness differ from previous reports, indicating the need for further investigation of the etiopathogenesis, earlier detection methods, and prevention.

Three-Dimensional Quantitative Magnetic Resonance Imaging of Epiphyseal Cartilage Vascularity Using Vessel Image Features: New Insights into Juvenile Osteochondritis Dissecans

We introduce a quantitative measure of epiphyseal cartilage vascularity and examine vessel networks during human skeletal maturation. Understanding early morphological changes in the distal femoral condyle is expected to provide information on the pathogenesis of developmental diseases such as juvenile osteochondritis dissecans.

Methods

Twenty-two cadaveric knees from donors ranging from 1 month to 10 years of age were included in the study. Images of bone, cartilage, and vascularity were acquired simultaneously with a 3-dimensional gradient-recalled-echo magnetic resonance imaging (MRI) sequence. The secondary ossification center volume and total epiphysis cartilage volume ratio and articular-epiphyseal cartilage complex and epiphyseal cartilage widths were measured. Epiphyseal cartilage vascularity was visualized for 9 data sets with quantitative susceptibility mapping and vessel filtering, resulting in 3-dimensional data to inform vessel network segmentation and to calculate vascular density.

Results

Three distinct, non-anastomosing vascular networks (2 peripheral and 1 central) supply the distal femoral epiphyseal cartilage. The central network begins regression as early as 3 months and is absent by 4 years. From 1 month to 3 years, the ratio of central to peripheral vascular area density decreased from 1.0 to 0.5, and the ratio of central to peripheral vascular skeletal density decreased from 0.9 to 0.6. A narrow, peripheral vascular rim was present at 8 years but had disappeared by 10 years. The secondary ossification center progressively acquires the shape of the articular-epiphyseal cartilage complex by 8 years of age, and the central areas of the medial and lateral femoral condyles are the last to ossify.

Conclusions

Using cadaveric pediatric knees, we provide quantitative, 3-dimensional measures of epiphyseal cartilage vascular regression during skeletal development using vessel image features. Central areas with both early vascular regression and delayed ossification correspond to predilection sites of juvenile osteochondritis dissecans in this limited case series. Our findings highlight specific vascular vulnerabilities that may lead to improved understanding of the pathogenesis and better-informed clinical management decisions in developmental skeletal diseases.

Clinical Relevance

This paradigm shift in understanding of juvenile osteochondritis dissecans etiology and disease progression may critically impact future patient management. Our findings highlight specific vascular vulnerabilities during skeletal maturation in a group of active young patients seen primarily by orthopaedic surgeons and sports medicine professionals.

Effects of supplementing organic microminerals and methionine with or without limiting growth during the rearing phase of replacement gilts on lameness, growth, and body composition

Previous research suggested that lameness in growing pigs could be reduced using feeding strategies, such as limiting growth rate and supplementing trace minerals (TM) and (or) methionine (Met). The present study evaluates effects of 1) TM and Met and 2) limiting total lysine (Lys) during the rearing phase (90 d) of gilts (as a means to limit growth rate) on lameness, performance, and sow claw health and productivity (to first parity). Gilts (n = 240; 58.0 ± 11.1 kg body weight [BW]) were blocked, distributed into pens of 10 gilts, and pens were allocated to a 2 × 2 factorial arrangement. Factors were: 1) control or TM plus Met, which provided additional 10, 20, and 50 mg/kg of chelated copper, manganese, and zinc, respectively (0.1%, Aplomotec Plus, Tecnología & Vitaminas, S.L.; Alforja, Spain), and a 1.01 Met:Lys ratio and 2) standard Lys was formulated to meet growth requirements or low Lys to 19% below growth requirements. Feeding was provided through two phases, first between 119 and 163 d of age (phase I) and the second between 163 and 209 d of age (phase II). Diets had 2.43 and 2.31 Mcal net energy/kg for phases I and II, respectively, and were offered ad libitum. Low Lys did not affect feed intake but rather reduced average daily gain (ADG) by 6.35% and the final BW by 3.80% compared with standard Lys (P < 0.001). Low Lys reduced ADG (P < 0.001) and gain:feed (P = 0.012) during phase I but not during phase II. Lameness prevalence was 7.92% during rearing and increased with time (P < 0.001). Final BW (151 kg) and ADG (989 g) were similar (P > 0.05) whether gilts displayed lameness or not. Lameness was low in severity and not affected by dietary factors. However, TM- plus Met-fed gilts were 19.2 kg heavier (P = 0.016) than were control at lameness detection. On the sow farm, there was no evidence for differences in lameness or claw lesions among previous dietary treatments. In conclusion, lameness prevalence during the rearing phase was similar, independent of TM plus Met supplement, low Lys, or the interaction. Insufficient reduction of ADG and low severity in lameness may have limited the potential of dietary treatments. Moreover, a greater deficiency of Lys would be needed to achieve the degree of growth reduction previously reported to lessen lameness through feed restriction.

Identification of Areas of Epiphyseal Cartilage Necrosis at Predilection Sites of Juvenile Osteochondritis Dissecans in Pediatric Cadavers

BACKGROUND

The pathogenesis of human juvenile osteochondritis dissecans (JOCD) remains poorly understood, with multiple factors implicated, including ischemia, repetitive trauma, and genetic predisposition. Similarities in the predilection site and the diagnostic and clinical features of JOCD to the well-characterized veterinary counterpart, osteochondrosis dissecans, suggest that, similar to the animal disease, the pathogenesis JOCD may also be initiated in the first few years of life, when disruption of blood supply to the epiphyseal growth cartilage leads to failure of endochondral ossification. To gather data in support of the hypothesis that JOCD and osteochondrosis dissecans have a shared pathogenesis, biopsy specimens obtained from predilection sites of JOCD in juvenile human cadavers were histologically examined to determine whether they contained lesions similar to those found in animals diagnosed with subclinical osteochondrosis dissecans.

METHODS

In this descriptive laboratory study, 59 biopsy specimens (6 mm in diameter) were harvested from the central aspect (i.e., the notch side) of the femoral condyles of 26 human cadavers (1 month to 11 years old). Specimens were histologically evaluated for the presence of areas of cartilage necrosis and the morphology of cartilage canal blood vessels.

RESULTS

Locally extensive areas of necrotic epiphyseal cartilage were identified in 4 specimens obtained from 3 donors (ages 2 to 4 years). Areas of cartilage necrosis accompanied by focal failure of endochondral ossification or surrounded by subchondral bone were identified in biopsy specimens from 4 donors (ages 4 to 9 years).

CONCLUSIONS

The identification of epiphyseal cartilage necrosis identical to that described in animals with subclinical osteochondrosis, found in biopsy specimens obtained from femoral predilection sites of JOCD in pediatric cadavers, suggests a shared pathogenesis of JOCD in humans and osteochondrosis dissecans in animals.

CLINICAL RELEVANCE

These findings imply that the pathogenesis of human JOCD likely starts 5 to 10 years prior to the development of clinical symptoms. Enhanced understanding of the temporal features of JOCD pathogenesis provides an opportunity for earlier diagnosis and treatment, likely resulting in improved outcomes for this condition in the future.

Septic Arthritis/Osteomyelitis May Lead to Osteochondrosis-Like Lesions in Foals

Failure of the cartilage canal blood supply leads to ischemic chondronecrosis which causes osteochondrosis, and osteochondral lesions. Osteochondrosis is a disease with a heritable component and usually occurs under aseptic conditions. Because bacteria can bind to growth cartilage and disrupt the blood supply in pigs and chickens, we considered whether this might play a role in development of equine osteochondrosis. The aim of this study was to examine whether bacteria are present in canals in the growth cartilage of foals with septic arthritis/osteomyelitis, and whether this is associated with osteochondrosis. The material consisted of 7 foals aged 9-117 days euthanized because of septic arthritis/osteomyelitis. The 7 cases had 16 lesions in growth cartilage that were evaluated histologically. Bacteria were present in cartilage canals in foals with septic arthritis/osteomyelitis. Portions of necrotic canals adjacent to bacteria frequently contained neutrophils, termed acute septic canals; or granulation tissue with neutrophils, termed chronic septic canals. Acute and chronic septic canals were associated with ischemic chondronecrosis in the articular-epiphyseal cartilage complex (AECC) of 5 cases and in the physis of 2 cases, and ossification was focally delayed in 5 of those 7 cases. Lesions occurred with and without adjacent osteomyelitis. Bacteria were present in cartilage canals and were associated with focal chondronecrosis in both the AECC and the physis. This establishes sepsis as a plausible cause of some osteochondral lesions in horses. It is recommended that horses with sepsis-related osteochondral lesions may be used for breeding without increasing the prevalence of OCD-predisposing genes in the population.

Characterization of cellular and matrix alterations in the early pathogenesis of osteochondritis dissecans in pigs using second harmonic generation and two-photon excitation fluorescence microscopy

Osteochondritis dissecans is a joint disease that is observed in several species. The disease can develop as a cause of ischemic chondronecrosis in the epiphyseal growth cartilage. Some lesions of chondronecrosis undergo spontaneous resolution, but it is not possible to predict whether a lesion will resolve or progress and require intervention. Proliferation of cells into clusters occurs at the lesion margin, but it is unclear if the clusters have a repair function. The aims of the current study were to examine clusters and potential matrix changes in response to ischemic chondronecrosis in the distal femur of 10 pigs aged 70-180 days using advanced microscopy based on two-photon excitation fluorescence and second harmonic generation. These microscopy techniques can perform 3D imaging of cells and collagen without staining. The results indicated a lower collagen density in the chondronecrotic areas compared to the normal growth cartilage, and fissures and breaks in the matrix integrity were demonstrated that potentially can propagate and cause osteochondritis dissecans. A higher number of cells in clusters was correlated with reduction in collagen density in the lesions. Some of the cells in the clusters had a morphology similar to progenitor cells, suggesting a potential repair role of the clusters. The study has shed further light on the secondary responses after initial lesion formation, which information can be of potential use to create models that can predict lesion progression and that may hence avoid unnecessary interventions in the future. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Repetitive Stresses Generate Osteochondral Lesions in Skeletally Immature Rabbits

BACKGROUND

The origin of juvenile osteochondritis dissecans (OCD) is unknown. Existing experimental animal models of OCD most frequently involve surgically created lesions but do not examine repetitive stress as a possible cause of OCD.

HYPOTHESIS

Repetitive stresses can cause OCD-like lesions in immature animals.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six juvenile rabbits were subjected to repetitive loading forces of approximately 160% body weight to the right hindlimb during five 45-minute sessions per week for 5 weeks. The contralateral limb was the unloaded control. After 5 weeks, rabbits were euthanized and examined with radiographs, micro-computed tomography, and gross and histopathologic analysis.

RESULTS

All 6 rabbits developed osteochondral lesions in loaded limbs on the medial and lateral femoral condyles, while contralateral unloaded limbs did not demonstrate lesions. Loaded limbs developed relative osteopenia in the femoral epiphysis and tibial metaphysis with associated decreased trabecular density. Loaded limbs also demonstrated increased femoral subchondral bone thickness near the lesions. Lesions did not have grossly apparent extensive articular cartilage damage; however, cartilage thickness increased on histology with reduced ossification. Loaded knees demonstrated abundant chondrocyte cloning, limited cartilage fissuring, and a focal loss of cellularity at the articular surface.

CONCLUSION

Low-grade lesions in human OCD have little gross articular cartilage involvement despite substantial changes to the subchondral bone as shown on magnetic resonance imaging and radiographs. Histopathology findings in this study included cartilage thickening and chondrocyte cloning resembling those of recently published human OCD biopsy studies. Our animal model supports the hypothesis that repetitive stress to immature knees may contribute to the development of human OCD. This model may be useful in understanding the pathophysiology and healing of human OCD.

CLINICAL RELEVANCE

Repetitive physiologic stress generated changes to the subchondral bone in immature animals without causing extensive articular damage. The similarities of these lesions in gross and histologic appearance with human OCD support repetitive stress as the likely the cause for human OCD.

Etiology and Pathogenesis of Osteochondrosis

Osteochondrosis is a common and clinically important joint disorder that occurs in human beings and in multiple animal species, most commonly pigs, horses, and dogs. This disorder is defined as a focal disturbance of enchondral ossification and is regarded as having a multifactorial etiology, with no single factor accounting for all aspects of the disease. The most commonly cited etiologic factors are heredity, rapid growth, anatomic conformation, trauma, and dietary imbalances; however, only heredity and anatomic conformation are well supported by the scientific literature. The way in which the disease is initiated has been debated. Although formation of a fragile cartilage, failure of chondrocyte differentiation, subchondral bone necrosis, and failure of blood supply to the growth cartilage all have been proposed as the initial step in the pathogenesis, the recent literature strongly supports failure of blood supply to growth cartilage as being the most likely. The term osteochondrosis has been used to describe a wide range of different lesions among different species. We suggest a refinement of this terminology to include the modifiers latens (lesion confined to epiphyseal cartilage), manifesta (lesion accompanied by delay in endochondral ossification), and dissecans (cleft formation through articular cartilage). The purpose of this review is to provide an overview of the disease, focusing on the most commonly cited theories, recent research findings, and our own views regarding the etiology and pathogenesis of osteochondrosis, in order to provide a better understanding of this apparently complex disease.

A Brief Review of Infrequent Spontaneous Findings, Peculiar Anatomical Microscopic Features, and Potential Artifacts in Göttingen Minipigs

Minipigs are now used in greater numbers in contract research organizations (CROs) as well as in the pharmaceutical industry. Most CROs or pharmaceutical companies use the Göttingen minipig, which displays a number of important background lesions. This review will discuss some of the more infrequent minipig background changes. Porcine stress syndrome is an autosomal recessive pharmacogenetic disorder in minipigs causing malignant hyperthermia and muscle necrosis. Possible triggers, clinical pathology as well as heart, muscle, liver, lung, and kidney histopathology are discussed. Additional spontaneous changes, background findings, and peculiar anatomical and histological features include thrombocytopenic purpura syndrome, spontaneous glomerulonephritis, osteochondritis, ellipsoids, or Schweigger–Seidel sheaths in the spleen, as well as the presence of a perimesenteric plexus adjacent to mesenteric lymph nodes, squamous epithelial metaplasia of the salivary gland, and cupping of the optic disk in the minipig eye. In order to maximize the data gained from minipig studies, the interpretation of pathology findings requires the input of experienced pathologists who understand the significance of artifacts and spontaneous, background lesions in minipigs and can distinguish these from induced lesions.

Novel Application of Magnetic Resonance Imaging Demonstrates Characteristic Differences in Vasculature at Predilection Sites of Osteochondritis Dissecans

BACKGROUND

Understanding the pathogenesis of osteochondrosis/osteochondritis dissecans and other developmental orthopaedic diseases that are thought to occur secondary to defects in vascular supply to growth/epiphyseal cartilage has been hampered by the inability to image the vasculature in this tissue. This is particularly true in human beings due to limitations of current imaging techniques and the lack of availability of appropriate cadaveric samples for histological studies.

HYPOTHESIS

Susceptibility-weighted imaging, an MRI sequence, allows identification of characteristic differences in the vascular architecture in species that are affected by osteochondrosis/osteochondritis dissecans on the femoral condyle (humans and pigs) versus a species that is free of the disease (goat).

STUDY DESIGN

Controlled laboratory study.

MATERIALS

Distal femora from cadavers of juvenile humans (n = 5), pigs (n = 3), and goats (n = 3) were scanned in a 9.4-T MRI scanner using susceptibility-weighted imaging. Three-dimensional reconstructions were created, and minimum intensity projections were calculated in 3 planes to enhance visualization of the vascular architecture.

RESULTS

Susceptibility-weighted imaging allowed clear visualization of the epiphyseal vasculature in all species. Vascular architecture, with vessels primarily arising from the perichondrium, was similar in humans and pigs, which are predisposed to osteochondrosis/osteochondritis dissecans, and was starkly different from that present in goats, a species in which there are no reports of osteochondrosis/osteochondritis dissecans. Furthermore, vessels in the distal femoral predilection site disappeared with age in humans in a pattern similar to that reported previously in pigs.

CONCLUSION

Nearly identical vascular architecture at the shared primary predilection site of osteochondrosis/osteochondritis dissecans in the femoral condyles in human beings and pigs suggests that vascular failure, which is known to be central to the pathogenesis of this disease in pigs, may also play a role in humans.

CLINICAL RELEVANCE

This assumption of a shared pathogenesis is supported by the pattern of disappearance of vessels with age at the primary predilection site of osteochondritis dissecans in humans, which is essentially identical to that which has been reported in pigs. Susceptibility-weighted imaging will likely help further elucidate this potential relationship in the future.

Development of a Large Animal Model of Osteochondritis Dissecans of the Knee: A Pilot Study

Background:

Treatment of osteochondritis dissecans (OCD) of the knee is challenging, and evidence for stage-dependent treatment options is lacking. Basic science approaches utilizing animal models have provided insight into the etiology of OCD but have yet to produce a reliable and reproducible large animal model of the disease on which to test new surgical strategies.

Purpose/Hypotheses:

The purpose of this study was to develop an animal model featuring an OCD-like lesion in terms of size, location, and International Cartilage Repair Society (ICRS) grading. The hypothesis was that surgical creation of an osteochondral defect followed by placement of a barrier between parent bone and progeny fragment would generate a reproducible OCD-like lesion.

Study Design:

Controlled laboratory study.

Methods:

Bilateral osteochondral lesions were created in the medial femoral condyles of 9 Yucatan minipigs. After lesion creation, a biodegradable membrane was interposed between the progeny and parent bone. Five different treatment groups were evaluated at 2 weeks: a control with no membrane (ctrl group; n = 4), a slowly degrading nanofibrous poly(∊-caprolactone) membrane (PCL group; n = 4), a fenestrated PCL membrane with 1.5-mm holes covering 25% of surface area (fenPCL group; n = 4), a collagen membrane (Bio-Gide) (CM group; n = 3), and a fenestrated CM (fenCM group; n = 3). Five unperturbed lateral condyles (1 from each treatment group) served as sham controls. After euthanasia on day 14, the lesion was evaluated by gross inspection, fluoroscopy, micro–computed tomography (micro-CT), and histology. To quantify changes between groups, a scoring system based on gross appearance (0-2), fluoroscopy (0-2), and micro-CT (0-6) was established. Micro-CT was used to quantify bone volume per total volume (BV/TV) in a defined region surrounding and inclusive of the defect.

Results:

The no scaffold group showed healing of the subchondral bone at 2 weeks, with continuity of subchondral bone elements. Conversely, condyles treated with PCL or CM showed substantial remodeling, with loss of bone in both the progeny fragment and surrounding parent bone. When these membranes were fenestrated (fenPCL and fenCM groups), bone loss was less severe. Histological analysis showed no integration in the cartilage layer in any treatment group, while fibrous tissue formed between the parent and progeny fragments. Micro-CT showed significant differences in mean BV/TV between the PCL (27.4% ± 2.3%) and the sham (47.7% ± 1.4%) or no scaffold (54.9% ± 15.1%) groups (P < .01 and P < .05, respectively). In addition, a significant difference in bone loss was evident between the PCL and fenPCL groups (mean BV/TV, 46.6% ± 15.2%; P < .05), as well as between the PCL and fenCM (mean BV/TV, 50.9% ± 3.5%) and fenPCL groups (P < .01). Grading by 6 blinded reviewers using an OCD scoring system with 3 subcategories showed a significant difference between control and PCL groups.

Conclusion:

This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs. The lesions generated matched characteristics of an ICRS grade 3 OCD lesion in humans. These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease.

Clinical Relevance:

This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

Surgical induction, histological evaluation, and MRI identification of cartilage necrosis in the distal femur in goats to model early lesions of osteochondrosis

OBJECTIVE

Identify and interrupt the vascular supply to portions of the distal femoral articular-epiphyseal cartilage complex (AECC) in goat kids to induce cartilage necrosis, characteristic of early lesions of osteochondrosis (OC); then utilize magnetic resonance imaging (MRI) to identify necrotic areas of cartilage.

DESIGN

Distal femora were perfused and cleared in goat kids of various ages to visualize the vascular supply to the distal femoral AECC. Vessels located on the axial aspect of the medial femoral condyle (MFC) and on the abaxial side of the lateral trochlear ridge were transected in eight 4- to 5-day-old goats to induce cartilage necrosis. Goats were euthanized 1, 2, 3, 4, 5, 6, 9, and 10 weeks post operatively and operated stifles were harvested. Adiabatic T1ρ relaxation time maps of the harvested distal femora were generated using a 9.4 T MR scanner, after which samples were evaluated histologically.

RESULTS

Interruption of the vascular supply to the MFC caused lesions of cartilage necrosis in 6/8 goat kids that were demonstrated histologically. Adiabatic T1ρ relaxation time mapping identified these areas of cartilage necrosis in 5/6 cases. No significant findings were detected after transection of perichondrial vessels supplying the lateral trochlear ridge.

CONCLUSIONS

Cartilage necrosis, characteristic of early OC, can be induced by interrupting the vascular supply to the distal femoral AECC in goat kids. The ability of high field MRI to identify these areas of cartilage necrosis in the AECC using the adiabatic T1ρ sequence suggests that this technique may be useful in the future for the early diagnosis of OC.

Effects of free-range and confined housing on joint health in a herd of fattening pigs

Background

Free-range housing, in which pigs have access to both indoor and outdoor areas, is mandatory in organic pig production in Europe, but little is known about the effects of this housing on joint health in pigs. A high level of joint condemnations at slaughter has been reported in organic free-range pigs in Sweden, compared with pigs raised in conventional confined housing. We hypothesised that biomechanical forces imposed on the joints of pigs that range freely promote the development of osteochondrosis and lead to joint condemnation. We compared the prevalence of osteochondrosis and other joint lesions (e.g. arthritis, traumatic) in the elbow and hock joints of 91 crossbred Hampshire (Yorkshire × Landrace) fattening pigs that were housed in a free-range indoor/outdoor system with that in 45 pigs housed in confined indoor pens.

Results

A larger proportion of free-range than confined pigs had osteochondrosis in the elbow joints (69 vs. 50%, p < 0.05), and a higher proportion of these joints in free-range pigs showed moderate or severe lesions (33 vs. 16%, p < 0.05). The free-range pigs also showed a higher prevalence of osteochondrosis in the hock joints (83 vs. 62%, p < 0.05) and a larger proportion of these joints had moderate or severe lesions (69 vs. 33%, p < 0.001). At slaughter, 4.2% of the free-range pigs had condemned joints, all of which showed severe osteochondrosis, while no joints of confined pigs were condemned.

Conclusions

In this experiment the prevalence of osteochondrosis in the elbow and the hock was higher, and lesions were more severe, in free-range than in confined pigs, suggesting that free-range housing increases the risk of acquiring osteochondrosis. Increased biomechanical stress to vulnerable joint structures may be the mechanism behind this effect, however more studies are needed to verify these results. This study suggests that modification of housing, and breeding for joints that are more adapted to free-range movement may be needed in free-range pig production. Severe osteochondrosis is a cause of joint condemnation, but the condemnation rate at slaughter underestimates the actual frequency of joint lesions and hence is a poor assessment of joint health.

Articular osteochondrosis: a comparison of naturally-occurring human and animal disease

BACKGROUND

Osteochondrosis (OC) is a common developmental orthopedic disease affecting both humans and animals. Despite increasing recognition of this disease among children and adolescents, its pathogenesis is incompletely understood because clinical signs are often not apparent until lesions have progressed to end-stage, and examination of cadaveric early lesions is not feasible. In contrast, both naturally-occurring and surgically-induced animal models of disease have been extensively studied, most notably in horses and swine, species in which OC is recognized to have profound health and economic implications. The potential for a translational model of human OC has not been recognized in the existing human literature.

OBJECTIVE

The purpose of this review is to highlight the similarities in signalment, predilection sites and clinical presentation of naturally-occurring OC in humans and animals and to propose a common pathogenesis for this condition across species.

STUDY DESIGN

Review.

METHODS

The published human and veterinary literature for the various manifestations of OC was reviewed. Peer-reviewed original scientific articles and species-specific review articles accessible in PubMed (US National Library of Medicine) were eligible for inclusion.

RESULTS

A broad range of similarities exists between OC affecting humans and animals, including predilection sites, clinical presentation, radiographic/MRI changes, and histological appearance of the end-stage lesion, suggesting a shared pathogenesis across species.

CONCLUSION

This proposed shared pathogenesis for OC between species implies that naturally-occurring and surgically-induced models of OC in animals may be useful in determining risk factors and for testing new diagnostic and therapeutic interventions that can be used in humans.

The influence of dietary restriction before and after 10 weeks of age on osteochondrosis in growing gilts

Osteochondrosis (OC) is one of the main causes of leg weakness causing premature culling in breeding sows and develops in a short time frame in young growing gilts. Dietary restriction may have different effects on OC prevalence depending on the age of the gilts. The aim of this study is to investigate age-dependent effects of dietary restriction, ad libitum vs. restricted (80% of ad libitum), on the occurrence of OC in gilts at slaughter (26 wk of age). At weaning (4 wk of age), 211 gilts were subjected to one of 4 treatments of a feeding regime. Gilts were administered either ad libitum feeding from weaning until slaughter (AA); restricted feeding from weaning until slaughter (RR); ad libitum feeding from weaning until 10 wk of age, after which gilts were switched to restricted feeding (AR); or restricted feeding from weaning until 10 wk of age, after which gilts were switched to ad libitum feeding (RA). At slaughter, the elbow, hock, and knee joints were harvested. Joints were scored macroscopically for articular surface deformations indicative of OC. Gilts in the RA treatment had significantly higher odds of being affected by OC than gilts in the RR and AR treatments in the hock joint (OR=3.3, P=0.04 and OR=8.5, P=0.002, respectively) and at animal level (OR=2.5, P=0.001 and OR=1.9, P=0.01, respectively). Gilts in the AA treatment had higher odds of being affected by OC than gilts in the AR treatment in the hock joint (OR=5.3, P=0.01). The results indicate a possible pathway to reduce the prevalence of OC in breeding gilts that will have to last several parities. Switching from restricted feeding to ad libitum feeding after 10 wk of age increases OC prevalence as opposed to restricted feeding after 10 wk of age.

Tissue mineral concentrations and osteochondrosis lesions in prolific sows across parities 0 through 7

Mortality in swine herds is often associated with lameness, and trace minerals are implicated in maintaining integrity of skeletal tissues. The objectives of this study were to determine if prolific sows displayed evidence of trace mineral depletion with age and to determine the prevalence of osteochondrosis (OC) lesions. Reduced mineral concentrations with age would support recommendations for an increase in the amount of dietary minerals. Tissue samples were collected from 66 sows selected to represent a cross-sectional profile of a prolific herd fed diets with inorganic sources of trace minerals fortified at concentrations typically found in commercial diets. Females ranged from nulliparous (parity 0) to parity 7 with a lifetime average of 12.9 ± 0.5 pigs born alive per litter. Minerals were assessed in humerus, scapula, ovary, liver, and muscle (psoas major) tissues. Percent bone ash increased (P < 0.05) with parity from 64 to 66% but differed among bone sections. The Ca (39.0%) and P (18.9%) concentrations in bone ash were essentially constant in all sections and parities. Bone Cu, Fe, Mn, and Zn concentrations varied among sections, but differences due to parity (P < 0.05) were only detected in Fe. Bone Fe decreased from approximately 49 μg/g ash in parity 0 and 1 sows to approximately 29 μg/g ash in parity 7, likely reflecting loss of hemopoietic tissue with age. No evidence was detected in liver for depletion of trace minerals across parity; however, liver Cu and Zn concentrations tended to increase with age. Liver Mn concentrations varied with parity, but no consistent trend with parity was evident. Ovary Cu and Mn concentrations varied dramatically as a function of the reproductive status, but no evidence was detected for depletion with parity. Articular surfaces of the distal scapula and proximal and distal humerus were evaluated grossly for prevalence of OC; bones were then sectioned to evaluate lesions in subchondral bone and physis. Incidence of OC lesions on the articular-epiphyseal cartilage complex varied among bone sites, but differences across parities were not detected. In a subset of sows with subchondral bone lesions, the lesions appeared severe enough to contribute to clinical lameness, particularly in the distal humerus site. However, none of the sows exhibited lameness at slaughter. As no reductions in mineral concentrations with age were detected, recommendations to increase dietary mineral supplementation with age were not supported.

High physiological demands in intensively raised pigs: impact on health and welfare

Genetic selection and better control of the environment of the pigs have resulted in increased production levels concerning both reproduction and growth. Such high performances imply high physiological demands that may deteriorate health and welfare. The aims of this paper are to review the physiological challenges that pigs are facing, to identify possible consequences on health and welfare, to propose ways of detecting and correcting problems whenever possible. At weaning, piglets are submitted to abrupt changes in food supply, housing and social environment. Behavioural changes and efficient adaptations of the digestive tract are critical for their health and welfare. Physiological demands to support these adaptations and risks of failure are inversely related to the age of the pigs. During fattening, modern pigs have high daily weight gain especially of lean tissue as well as elevated feed conversion rate. These high growth performances are suspected to favour stress and disease susceptibility, undesirable behaviours as well as leg weakness, but further experimental data are necessary to validate these effects and find their origin. In reproductive females, high prolificacy generates elevated foetal demands for nutrients and space that are not fully met as shown by an increased number of light piglets having difficulties to adapt successfully to the neonatal life. During lactation, sows with high milk production have high nutrient requirements leading to intense catabolism that may affect their health, welfare and future reproductive abilities.

Associations between osteochondrosis and conformation and locomotive characteristics in pigs

Conformation and locomotive characteristics (CLC; i.e., leg conformation and gait movement patterns) may be associated with osteochondrosis (OC) in pigs. Osteochondrosis and CLC increase the risk of premature culling. This study investigated whether CLC have an explanatory value, over the previously modeled effects of sex, feeding, and housing conditions, on the occurrence and severity of OC in several joints and at the animal level. At 154 to 156 d of age, 267 pigs were subjectively scored on 9 conformation and 2 locomotive characteristics. Scoring was performed on a 9-point linear grading scale. For conformation characteristics, score 5 indicated normal conformation and scores 1 and 9 indicated severe deviations from normal. For the locomotive characteristics, score 1 indicated normal locomotion and score 9 indicated severe deviation from normal. At 161 to 176 d of age, pigs were slaughtered and joints were dissected for macroscopic evaluation of OC status. Results showed that swaying hindquarters and a stiffer gait were associated with greater scores for OC in, respectively, the femoropatellar (P = 0.018) and tarsocrural joint (P = 0.005), smaller inner claws as compared with the outer claws of the front legs was associated with lower scores for OC than equally sized claws in the femoropatellar joint (P = 0.021) and on animal level (P = 0.010), steep and weak pasterns of the front legs were associated with greater scores for OC in the elbow joint (P = 0.004) and on animal level (P = 0.018), X-shaped hind legs was associated with greater scores for OC on animal level (P = 0.037), and steep and weak pasterns of the hind legs were associated with lower scores for OC than normal conformation in the tarsocrural joint (P = 0.05). This study found several CLC that were associated with OC in several joints and at an animal level. This study showed that certain CLC might be used as indicators of OC and included in the criteria for selection of replacement animals for the breeding herd.

Association and expression study of MMP3, TGFβ1 and COL10A1 as candidate genes for leg weakness-related traits in pigs

The present study was aimed to determine the association between metalloproteinase 3 (MMP3), transforming growth factor beta 1 (TGFβ1) and collagen type X alpha I (COL10A1) gene polymorphisms with traits related to leg weakness in pigs. Three hundred Duroc × Pietrain cross breds (DuPi) and 299 pigs of a commercial population (CP) were used for the experiment. DuPi animals were examined for 10 different traits describing leg and feet structure, osteochondrosis (OC) scores and bone density status. Data of OC score at condylus medialis humeri, condylus medialis femoris and distal epiphysis ulna regions of CP were used for association analysis. Significant association (P < 0.05) was found for MMP3 SNP (g.158 C>T) with OC at head of femur and bone mineral density in the DuPi population. Association (P < 0.05) was found between SNP of TGFβ1 (g.180 G>A) with rear leg score and the principle component denoting both OC and feet and leg scores in the DuPi population. No association was found between COL10A1 (g.72 C>T) and leg weakness related traits. The associations of SNPs with OC traits could not be confirmed in the commercial population. Expression analysis of the three candidate genes was performed to compare between healthy and OC. TGFβ1 was found to be highly expressed (P < 0.05) in the OC compared to healthy cartilages, but no significant different expressions were observed for MMP3 and COL10A1 genes. The present finding suggested that TGFβ1 and MMP3 genes variants have an effect on some of the leg weakness related traits.

Use of serum biomarkers to predict the development and severity of osteochondrosis lesions in the distal portion of the femur in pigs

OBJECTIVE

To evaluate the use of serum biomarkers of cartilage and bone metabolism to predict the occurrence and severity of osteochondrosis (OC) lesions in the distal portion of the femur in growing swine.

ANIMALS

71 gilts.

PROCEDURES

At an abattoir, serum samples for analysis of 10 biomarkers indicative of cartilage and bone metabolism were obtained prior to processing of the pigs. The distal portion of each pig's left femur was directly examined and cut into longitudinal sections to evaluate the number and severity of abnormalities on the external surface, articular cartilage, and growth plate. Each specimen was categorized as with (n = 56) or without (15) OC, and an overall OC severity score was assigned to affected pigs. Logistic and linear regression analyses were performed to predict odds of OC on the basis of biomarker concentrations and predict the severity of OC values in affected pigs, respectively.

RESULTS

Compared with values in unaffected pigs, serum concentrations of C-propeptide of type II collagen (CPII) and cartilage oligomeric matrix protein were significantly increased and concentrations of carboxy-terminal telopeptide of type II collagen 3/4-length fragment (C2C) and pyridinoline cross-links were significantly decreased in affected pigs. A 2-fold increase in CPII concentration increased the odds of pigs having OC by a factor of 97 (95% confidence interval, 6 to infinity). Changes in serum C2C concentration accounted for 49% of the variation in overall OC severity score.

CONCLUSIONS AND CLINICAL RELEVANCE

Assessment of serum biomarker concentrations may be useful in the diagnosis of OC and aid in reduction of lameness in swine herds.

Molecular characterization and methylation study of matrix gla protein in articular cartilage from pig with osteochondrosis

Osteochondrosis (OC) or leg weakness is an economically important disease of young fast growing pigs and is a concern of animal welfare. The etiology and pathogenesis of osteochondrosis is not fully understood yet, but any abnormalities in the formation of hypertrophic chondrocytes and disrupted blood supply to the growth cartilage are very important predisposing factors. Matrix gla protein (MGP) as a potential calcification inhibitor of extracellular matrix might contribute to the development of OC. Molecular characterization, polymorphisms analysis, methylation at promoter region and expression of MGP gene and protein were performed in both healthy and OC cartilage collected from a DurocxPietrain resource population. The porcine MGP gene consists of 4 exons and 3 introns. The full-length MGP cDNA isolated from articular cartilage consists of 606 bp with a 69-bp 5' UTR, a 312-bp open reading frame with a start codon, a 225-bp 3' UTR. Three single-nucleotide polymorphisms (SNP) were detected in the intron 1 (A-115G, C-1073T and C-1135A) and one in the 3'UTR (C-3767T). The relative abundance of MGP mRNA was lower (P<0.05) in OC compared with healthy cartilage. Moreover, the intensity of MGP band was lower (P<0.05) in OC group when quantified by western blot. Furthermore, one CpG region was identified in MGP promoter and DNA methylation of three CG sites were higher in OC compared with normal cartilage. This suggested that the high DNA methylation at specific CG sites in the MGP promoter might be involved in the down regulation of MGP in OC. Immunofluorescence of normal cartilage collected from pigs of different ages revealed that MGP signals were higher in younger pigs and decreased in the older pigs. The MGP protein was expressed more near to the cartilage canals. These results suggest that the MGP gene might be a potential candidate gene for the development of OC in pigs.

Osteochondrosis of the elbow joint in finishing pigs from three herds: associations among different types of joint changes and between osteochondrosis and growth rate

Osteochondrosis (OC) is a degenerative condition of the cartilage seen in growing animals. The objective of the study was to investigate (1) the prevalence of macroscopically visible OC in the elbow of finishing pigs, (2) the relationship between changes in the surface of the articular cartilage and changes in the underlying cartilage and bone and the synovial membrane, and (3) the association between growth rate and the occurrence of OC in the elbow. The study used 9696 finishing pigs from three herds. After slaughter, the left elbow joint of each pig was examined, and macroscopically visible lesions in the articular cartilage, subchondral bone and synovial membrane were recorded. The highest prevalences of OC lesions were found in the humeral condyle with thickening of the articular cartilage (53%), irregularity of the articular cartilage (32%), lesions in the subchondral bone (26%), fissures under the cartilage (21%) and osteochondrosis dissecans (OCD) (14%). Irregularity of the articular cartilage was strongly associated with fissures under the cartilage and lesions in the subchondral bone (OR 13.7 and 5.8, respectively). Irregularity of the articular cartilage and OCD were associated with villous proliferation of the synovial membrane. For each additional 100 g of average daily gain in the weaner period or in the finishing period, the risk of irregularity in the articular cartilage and OCD increased by approximately 20% (ORs ranging between 1.14 and 1.20 for both weaners and finishers).

Large-scale association study for structural soundness and leg locomotion traits in the pig

BACKGROUND

Identification and culling of replacement gilts with poor skeletal conformation and feet and leg (FL) unsoundness is an approach used to reduce sow culling and mortality rates in breeding stock. Few candidate genes related to soundness traits have been identified in the pig.

METHODS

In this study, 2066 commercial females were scored for 17 traits describing body conformation and FL structure, and were used for association analyses. Genotyping of 121 SNPs derived from 95 genes was implemented using Sequenom's MassARRAY system.

RESULTS

Based on the association results from single trait and principal components using mixed linear model analyses and false discovery rate testing, it was observed that APOE, BMP8, CALCR, COL1A2, COL9A1, DKFZ, FBN1 and VDBP were very highly significantly (P < 0.001) associated with body conformation traits. The genes ALOX5, BMP8, CALCR, OPG, OXTR and WNT16 were very highly significantly (P < 0.001) associated with FL structures, and APOE, CALCR, COL1A2, GNRHR, IHH, MTHFR and WNT16 were highly significantly (P < 0.01) associated with overall leg action. Strong linkage disequilibrium between CALCR and COL1A2 on SSC9 was detected, and haplotype -ACGACC- was highly significantly (P < 0.01) associated with overall leg action and several important FL soundness traits.

CONCLUSION

The present findings provide a comprehensive list of candidate genes for further use in fine mapping and biological functional analyses.

Effect of dietary nutrients on osteochondrosis lesions and cartilage properties in pigs

OBJECTIVE

To evaluate dietary ingredients involved in cartilage and bone metabolism and their influence on osteochondrosis lesions in swine.

ANIMALS

80 crossbred gilts (mean initial weight, 39 kg).

PROCEDURES

Pigs (10 pigs/treatment) were fed a corn-soybean meal basal (control) diet or the basal diet supplemented with additional minerals (copper and manganese or silicon), amino acids (proline and glycine; a combination of leucine, isoleucine, and valine; or methionine and threonine), or fatty acids (provided by fish oil) for 84 days. Pigs were then slaughtered and the distal portion of the left femur was collected for determination of osteochondrosis lesions at the femoral condyle. After evaluation of external joint surfaces, the distal portion of the femur was sectioned to evaluate lesions in the growth plate and articular cartilage. Additionally, a cartilage specimen was obtained from the patella for analysis.

RESULTS

Pigs fed diets containing high amounts of methionine and threonine or the diet containing all additional ingredients had significantly lower total severity scores, compared with scores for pigs fed the control diet or a diet supplemented with fish oil. Pigs fed diets containing additional proline and glycine, copper and manganese, methionine and threonine, or all additional ingredients had significantly lower overall scores, compared with scores for pigs fed the control diet or a diet supplemented with fish oil.

CONCLUSIONS AND CLINICAL RELEVANCE

Dietary manipulation decreased the severity of osteochondrosis lesions, compared with results for pigs fed a control diet. However, additional research on optimal concentrations and combinations of dietary components is needed.

Genetic parameters for osteochondrosis traits in elbow joints of crossbred pigs and relationships with production traits

A total of 9360 offspring of 12 purebred Duroc sires and 692 Landrace × Yorkshire sows were evaluated for six osteochondrosis traits in the left elbow joints at slaughter. Osteochondrosis traits, growth pre- and post weaning, and meat content at slaughter were analysed simultaneously by a multivariate genetic model. Castrates scored worse than female pigs for nearly all osteochondral traits. Heritability of elbow osteochondrosis was moderate (0·02 to 0·28) and, thus, selection against the disorder is possible. Phenotypic correlations among joint surface abnormalities, cartilage thickness, subchondral lesions and cracks in the cartilage at the osteochondral junction in the medial condyle ranged from 0·33 to 0·69, whereas genetic correlations ranged from 0·75 to 0·97. Phenotypic correlations of the sagittal central groove with other abnormalities in the medial condyle were low and insignificant but genetic correlations were strongly significant (0·66 to 0·77). Depression of the proximal edge of the radius was to some extent phenotypically correlated to abnormalities in the medial humeral condyle (around 0·2), while genetic correlations ranged from 0·05 to 0·52. Significant genetic correlations among osteochondral traits indicate that all are part of the osteochondrosis complex. Abnormalities in the joint surface showed the strongest genetic correlations with other osteochondrosis variables in the elbow joint and were moderately inherited (h2= 0·22), which indicates that this trait can be used as a marker to select against osteochondrosis. Osteochondral traits had no significant genetic correlations with growth to weaning and to 30 kg, slight negative (favourable) genetic correlations with growth from 30 to 100 kg, and slightly positive (unfavourable) genetic correlations with meat content in carcass.

Consequences of hazardous dietary calcium deficiency for fattening bulls

Background

Deficient mineral supplementation on a feedlot farm resulted in severe clinical manifestations in fattening bulls. Animals mistakenly received only 60–70% of the recommended calcium intake, while simultaneously receiving twice the amount of phosphorus recommended. Thus, the dietary Ca/P ratio was severely distorted. After approximately six months on such a diet, four fattening bulls were euthanized because of severe lameness and 15% of other animals on the farm were having clinical leg problems. Veterinary consultation revealed the mistake in mineral supplementation.

Methods

Fattening bulls were divided into three groups depending on the time of their arrival to the farm. This enabled the effect of mineral imbalance at different growth phases to be examined. After slaughtering, the bones of both front and hind limbs were macroscopically evaluated.

Results

Over 80% of the animals with a calcium-deficient diet had at least one severe osteoarthritic lesion. The economic impact of the calcium deficiency was statistically significant.

Conclusion

Calcium deficiency with distorted Ca/P ratio yielded a severe outbreak of osteoarthritis in fattening bulls. Calcium deficiency caused a more serious lesions in age group 5–12 months than age group 12–18 months. Besides causing obvious economic losses osteoarthritis is also a welfare issue for feedlot animals.