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.

Osteochondrosis in the central and third tarsal bones of young horses.

Recently, the central and third tarsal bones of 23 equine fetuses and foals were examined using micro-computed tomography. Radiological changes, including incomplete ossification and focal ossification defects interpreted as osteochondrosis, were detected in 16 of 23 cases. The geometry of the osteochondrosis defects suggested they were the result of vascular failure, but this requires histological confirmation. The study aim was to examine central and third tarsal bones from the 16 cases and to describe the tissues present, cartilage canals, and lesions, including suspected osteochondrosis lesions. Cases included 9 males and 7 females from 0 to 150 days of age, comprising 11 Icelandic horses, 2 standardbred horses, 2 warmblood riding horses, and 1 coldblooded trotting horse. Until 4 days of age, all aspects of the bones were covered by growth cartilage, but from 105 days, the dorsal and plantar aspects were covered by fibrous tissue undergoing intramembranous ossification. Cartilage canal vessels gradually decreased but were present in most cases up to 122 days and were absent in the next available case at 150 days. Radiological osteochondrosis defects were confirmed in histological sections from 3 cases and consisted of necrotic vessels surrounded by ischemic chondronecrosis (articular osteochondrosis) and areas of retained, morphologically viable hypertrophic chondrocytes (physeal osteochondrosis). The central and third tarsal bones formed by both endochondral and intramembranous ossification. The blood supply to the growth cartilage of the central and third tarsal bones regressed between 122 and 150 days of age. Radiological osteochondrosis defects represented vascular failure, with chondrocyte necrosis and retention, or a combination of articular and physeal osteochondrosis.

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.

A systematic review evaluating the use of ultrasound in the identification of osteochondrosis in horses.

Osteochondrosis is commonly encountered in young horses, with welfare, performance, and economic effects. Consequently, pre-purchase radiographic screening for osteochondrosis is routinely performed. Ultrasonographic examination of articular cartilage and osteochondrosis lesions are described in the literature with many case series or single case reports published. This systematic review was undertaken to examine the evidence for using ultrasonography in comparison to traditional radiography, arthroscopy or necropsy findings in the detection of osteochondrosis. The systematic review identified a paucity of studies in which there was marked variation in the populations, sample size, methods and results reported. Currently, there is no strong evidence confirming the diagnostic accuracy and validity of ultrasonography in the detection of osteochondral lesions in the relevant joints in horses.

A systematic review on conservative treatment options for OSGOOD-Schlatter disease.

OBJECTIVES: Osgood-Schlatter disease (OSD) is a sport- and growth-associated knee pathology with locally painful alterations around the tibial tuberosity apophysis. Up to 10% of adolescents are affected by OSD. Treatment is predominantly conservative. The aims of this systematic review are to comprehensively identify conservative treatment options for OSD, compare their effectiveness in selected outcomes, and describe potential research gaps. METHODS: A systematic literature search was conducted using CENTRAL, CINAHL, EMBASE, MEDLINE, and PEDro databases. In addition, ongoing and unpublished clinical studies, dissertations, and other grey literature on OSD were searched. We also systematically retrieved review articles for extraction of treatment recommendations. RESULTS: Of 767 identified studies, thirteen were included, comprising only two randomised controlled trials (RCTs). The included studies were published from 1948 to 2019 and included 747 patients with 937 affected knees. Study quality was poor to moderate. In addition to the studies, 15 review articles were included, among which the most prevalent treatment recommendations were compiled. CONCLUSION: Certain therapeutic approaches, such as stretching, have apparent efficacy, but no RCT comparing specific exercises with sham or usual-care treatment exists. Carefully controlled studies on well-described treatment approaches are needed to establish which conservative treatment options are most effective for patients with OSD.

Posterior Tibial Slope is Increased in Patients With Tibial Tubercle Fractures and Osgood-Schlatter Disease.

BACKGROUND: Osgood-Schlatter disease (OSD) and tibial tubercle fractures are pathologies that affect the tibial tubercle apophysis in preadolescents and adolescents. Anatomic alignment of the proximal tibia may explain why some children develop OSD or sustain tibial tubercle fractures and some do not. Recent data has shown an association between posterior tibial slope angle (PTSA) and both OSD and proximal tibia physeal fractures. In this study, we compare radiographic parameters between patients with non-OSD knee pain, knees with OSD, and knees with tibial tubercle fracture to elucidate a difference between these groups. METHODS: Patients treated for OSD, tibial tubercle fractures, and knee pain, from 2012 to 2018, were retrospectively reviewed. Radiographic parameters for each study group included PTSA, anatomic lateral distal femoral angle, anatomic medial proximal tibial angle, patellar articular height, and the distance from the inferior aspect of the patellar articular surface. Caton-Deschamps index was then calculated. Demographic data was collected including age, sex, and body mass index. Demographic and radiographic data was compared using analysis of variance tests, χ2 tests, 2-sample t tests, and multiple linear regression. RESULTS: Two hundred fifty-one knees in 229 patients met inclusion criteria for the study. In all, 76% were male and the average age of the overall cohort was 14 years old. In patients with tibial tubercle fractures, the majority of fractures were Ogden type 3b (65%). After controlling for demographic variability, average PTSA in the fracture cohort was significantly greater than that in the control cohort (ß=3.49, P<0.001). The OSD cohort had a significantly greater posterior slope (ß=3.14) than the control cohort (P<0.001). There was no statistically significant difference between the fracture and OSD cohorts. There was also no difference in Caton-Deschamps index between the 2 study groups when compared with the control group. CONCLUSION: This study demonstrates that patients with tibial tubercle fractures and patients with OSD have an increased PTSA when compared with the control group. This information adds to the body of evidence that increased tibial slope places the proximal tibial physis under abnormal stress which may contribute to the development of pathologic conditions of proximal tibia such as OSD and tibial tubercle fractures. LEVEL OF EVIDENCE: Level III; retrospective comparative study.

Osteochondral repair combining therapeutics implant with mesenchymal stem cells spheroids.

Functional articular cartilage regeneration remains challenging, and it is essential to restore focal osteochondral defects and prevent secondary osteoarthritis. Combining autologous stem cells with therapeutic medical device, we developed a bi-compartmented implant that could promote both articular cartilage and subchondral bone regeneration. The first compartment based on therapeutic collagen associated with bone morphogenetic protein 2, provides structural support and promotes subchondral bone regeneration. The second compartment contains bone marrow-derived mesenchymal stem cell spheroids to support the regeneration of the articular cartilage. Six-month post-implantation, the regenerated articular cartilage surface was 3 times larger than that of untreated animals, and the regeneration of the osteochondral tissue occurred during the formation of hyaline-like cartilage. Our results demonstrate the positive impact of this combined advanced therapy medicinal product, meeting the needs of promising osteochondral regeneration in critical size articular defects in a large animal model combining not only therapeutic implant but also stem cells.

Molecular Processes in Chondrocyte Biology.

Chondrocyte biology is a hot topic, because osteoarthritis (OA) is a serious problem in an aging society, but there are no fundamental therapeutic drugs [...].

Proteome Alterations in Equine Osteochondrotic Chondrocytes.

Osteochondrosis is a failure of the endochondral ossification that affects developing joints in humans and several animal species. It is a localized idiopathic joint disorder characterized by focal chondronecrosis and growing cartilage retention, which can lead to the formation of fissures, subchondral bone cysts, or intra-articular fragments. Osteochondrosis is a complex multifactorial disease associated with extracellular matrix alterations and failure in chondrocyte differentiation, mainly due to genetic, biochemical, and nutritional factors, as well as traumas. This study describes the main proteomic alterations occurring in chondrocytes isolated from osteochondrotic cartilage fragments. A comparative analysis performed on equine osteochondrotic and healthy chondrocytes showed 26 protein species as differentially represented. In particular, quantitative changes in the extracellular matrix, cytoskeletal and chaperone proteins, and in cell adhesion and signaling molecules were observed in osteochondrotic cells, compared to healthy controls. Functional group analysis annotated most of these proteins in "growth plate and cartilage development", while others were included in "glycolysis and gluconeogenesis", "positive regulation of protein import", "cell-cell adhesion mediator activity", and "mitochondrion nucleoid". These results may help to clarify some chondrocyte functional alterations that may play a significant role in determining the onset and progression of equine osteochondrosis and, being related, of human juvenile osteochondrosis.

Computed tomographic development of physeal osteochondrosis in pigs.

BACKGROUND: Articular osteochondrosis follows a dynamic development pattern. Lesions arise, in incidence peaks compatible with failure of cartilage canal vessels during incorporation into bone, and can also resolve. Lesions that resolve before examination at a single time point will constitute false-negative diagnoses. The aim of the study was to identify physeal osteochondrosis lesions in pigs and monitor their development by computed tomography (CT), to determine if they follow a similar dynamic development pattern to articular osteochondrosis. RESULTS: Thirteen physes were evaluated bilaterally in up to eight biweekly CT scans from 18 male Landrace pigs age 70-180 days (total: 112 scans), generating 2912 scores. There were 1754 (60%) lesion-negative scores and 1158 (40%) lesion-positive scores. Positive scores comprised 138 lesions present at the start and 235 lesions that developed during the study, from 4 to 32 lesions per physis (median: 15 lesions). There were 1-2 peaks in the incidence curves for 12/13 examined physes, the exception being the proximal humerus. Positive scores also included 785 times that lesions persisted, from 1.3-4.8 examination intervals per lesion (median: 2.8 intervals). Negative scores included 190 times that lesions resolved, from 19 to 100% of lesions per physis (median: 65%). Lesions resolved by filling with bone from marginal sclerosis and reparative ossification centres. In the distal scapula and distal fibula, perichondrial new bone formation occurred that led to permanent enlargement of physeal regions. Angular limb deformity was not identified in any pig. CONCLUSIONS: Physeal osteochondrosis followed a similar dynamic development pattern to articular osteochondrosis. There were peaks in the incidence curves, compatible with failure of vessels during incorporation into bone. In some physes, osteochondrosis led to permanent enlargement, potentially relevant for decubital ulcers. The relationship between physeal osteochondrosis and angular limb deformity must be examined further in pigs over 6 months old in future.

A new and simplified comprehensive ultrasound protocol of haemophilic joints: the Universal Simplified Ultrasound (US-US) protocol.

AIM: To present a new protocol to optimise ultrasound (US) assessment of haemophilic arthropathy. MATERIALS AND METHODS: Ultrasound of haemophilic arthropathy joints was performed using three different ultrasound protocols, namely, the Toronto-Vellore Comprehensive Ultrasound (TVC-US) protocol, the Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US), and the newly developed Universal Simplified Ultrasound (US-US) protocol. Synovial hypertrophy, haemosiderin deposition, effusion, erosion, and cartilage loss were evaluated in 20 joints. The reliability and diagnostic efficiency of these protocols was compared using magnetic resonance imaging (MRI). RESULTS: The correlation between the TVC-US and US-US protocols for synovial hypertrophy was excellent: kappa significance (KS) was 1, but was substantial (KS=0.65) with the HEAD-US protocol. For effusion, both the TVC-US and the HEAD-US protocols had substantial correlation with the US-US protocol (KS=0.7 and 0.6 respectively). The correlation for erosion and cartilage loss was excellent between the TVC-US and the US-US with MRI (KS=1), but poor (KS=0) with the HEAD-US protocol. The US-US protocol also had good interobserver agreement (KS=1). CONCLUSION: The accuracy of the US-US protocol is comparable to the TVC-US protocol and MRI and is superior to the HEAD-US protocol in the assessment of haemophilic arthropathy.

Osteochondrosis in the Distal Femoral Physis of Pigs Starts With Vascular Failure.

Articular osteochondrosis (OC) arises due to vascular failure and ischemic chondronecrosis. The aim of the study was to describe the histological and computed tomographic (CT) characteristics of changes in the distal femoral physis of pigs, to determine if they represented OC lesions and if the pathogenesis was the same as for articular OC. The material included 19 male Landrace pigs bred for predisposition to OC. One or 2 pigs were euthanized and CT-scanned at 2-week intervals from 82 to 180 days of age. Material from 10 pigs was available for histological validation. The CT scans revealed 31 lesions confirmed in 3 planes and 1 additional macroscopically visible lesion confirmed in 2 CT planes. Twelve of the lesions were histologically validated. All lesions were compatible with OC. Cartilage canal and eosinophilic streak morphological changes corresponded to failure of end arteries coursing from the epiphysis, toward the metaphysis. The location of lesions was compatible with failure at the point of vessel incorporation into bone. Vascular failure was associated with retention of viable hypertrophic chondrocytes and delayed ossification but not cartilage necrosis. Lesion width ranged from 1.1% to 45.6% of the physis. Several lesions were expected to resolve due to small size and evidence of CT-identifiable, reparative ossification. Angular limb deformity was not detected in any pig. The pathogenesis of physeal OC started with vascular failure that was morphologically identical to articular OC. The heritable predisposition may therefore be the same. The association between lesions and limb deformity should be studied further in older pigs in future.

Prevalence of osteochondral lesions in the fetlock and hock joints of Standardbred horses that survived bacterial infection before 6 months of age.

BACKGROUND: Young Standardbred horses frequently develop fragments in joints. Some fragments represent osteochondrosis; others are considered developmental, but it is uncertain whether they result from preceding osteochondrosis. Osteochondrosis occurs as a consequence of failure of the cartilage canal blood supply and ischaemic chondronecrosis. In heritably predisposed foals, failure was associated with incorporation of vessels into bone. However, bacterial vascular failure was also recently documented in foals suffering spontaneous infections, proving that bacteria can cause osteochondral lesions in foals up to 150 days old. The aim was to determine prevalence of fetlock and hock lesions at screening age in Standardbred horses that survived infections before 6 months of age, and compare this to prevalence reported in the literature. METHODS: The material consisted of 28 Standardbred horses; 17 males and 11 females that presented and were diagnosed clinically with bacterial infections from 1 to 150 days of age (average: 41.3 days). A screening set of 8 radiographic projections was available from all 28 horses at 7-85 months of age (average: 23.6 months). Lesion prevalence was compared to three previously reported Standardbred cohorts. RESULTS: Osteochondral lesions were detected in one or more joints of 19/28 horses (67.9%); in the fetlock joint of 14/28 horses (50%) and the hock joint of 11/28 horses (39.3%). These prevalences were ≥ 2 x higher than the corresponding prevalences in the comparison cohorts, and statistically significantly so in 5:6 comparisons (p-values from < 0.00001 to 0.01). In the sepsis cohort, there were an average of 2.3 affected joints and 2.5 lesions per affected horse, whereas there in the one comparable literature cohort were an average of 1.5 affected joints and 1.7 lesions per affected horse. CONCLUSIONS: Standardbred horses that survived bacterial infections before 6 months of age had more osteochondral lesions than literature comparison cohorts at screening age. The implication was that some of the lesions in this group were caused by bacteria. It may become necessary to develop methods for differentiating between acquired, septic and aseptic, heritably predisposed lesions.

Juvenile osteochondritis dissecans of the knee is a result of failure of the blood supply to growth cartilage and osteochondrosis.

OBJECTIVE: Juvenile osteochondritis dissecans (JOCD) is similar to osteochondrosis dissecans (OCD) in animals, which is the result of failure of the cartilage canal blood supply, ischemic chondronecrosis and delayed ossification, or osteochondrosis. The aim of the current study was to determine if osteochondrosis lesions occur at predilection sites for JOCD in children. METHOD: Computed tomographic (CT) scans of 23 knees (13 right, 10 left) from 13 children (9 male, 4 female; 1 month to 11 years old) were evaluated for lesions consisting of focal, sharply demarcated, uniformly hypodense defects in the ossification front. Histological validation was performed in 11 lesions from eight femurs. RESULTS: Thirty-two lesions consisting of focal, uniformly hypodense defects in the ossification front were identified in the CT scans of 14 human femurs (7 left, 7 right; male, 7-11 years old). Defects corresponded to areas of ischemic chondronecrosis in sections from all 11 histologically validated lesions. Intra-cartilaginous secondary responses comprising proliferation of adjacent chondrocytes and vessels were detected in six and two lesions, whereas intra-osseous responses including accumulation of chondroclasts and formation of granulation tissue occurred in 10 and six lesions, respectively. One CT cyst-like lesion contained both a pseudocyst and a true cyst in histological sections. CONCLUSION: Changes identical to osteochondrosis in animals were detected at predilection sites for JOCD in children, and confirmed to represent failure of the cartilage canal blood supply and ischemic chondronecrosis in histological sections.

Arthroscopic near infrared spectroscopy enables simultaneous quantitative evaluation of articular cartilage and subchondral bone in vivo.

Arthroscopic assessment of articular tissues is highly subjective and poorly reproducible. To ensure optimal patient care, quantitative techniques (e.g., near infrared spectroscopy (NIRS)) could substantially enhance arthroscopic diagnosis of initial signs of post-traumatic osteoarthritis (PTOA). Here, we demonstrate, for the first time, the potential of arthroscopic NIRS to simultaneously monitor progressive degeneration of cartilage and subchondral bone in vivo in Shetland ponies undergoing different experimental cartilage repair procedures. Osteochondral tissues adjacent to the repair sites were evaluated using an arthroscopic NIRS probe and significant (p < 0.05) degenerative changes were observed in the tissue properties when compared with tissues from healthy joints. Artificial neural networks (ANN) enabled reliable (ρ = 0.63-0.87, NMRSE = 8.5-17.2%, RPIQ = 1.93-3.03) estimation of articular cartilage biomechanical properties, subchondral bone plate thickness and bone mineral density (BMD), and subchondral trabecular bone thickness, bone volume fraction (BV), BMD, and structure model index (SMI) from in vitro spectral data. The trained ANNs also reliably predicted the properties of an independent in vitro test group (ρ = 0.54-0.91, NMRSE = 5.9-17.6%, RPIQ = 1.68-3.36). However, predictions based on arthroscopic NIR spectra were less reliable (ρ = 0.27-0.74, NMRSE = 14.5-24.0%, RPIQ = 1.35-1.70), possibly due to errors introduced during arthroscopic spectral acquisition. Adaptation of NIRS could address the limitations of conventional arthroscopy through quantitative assessment of lesion severity and extent, thereby enhancing detection of initial signs of PTOA. This would be of high clinical significance, for example, when conducting orthopaedic repair surgeries.

Incidence and characteristics of juvenile tarsocrural osteochondrosis in purebred Angus bulls.

Osteochondrosis (OC) of the bovine tarsus has been suggested to contribute to osteoarthritis. The objective of this prospective cohort study was to provide data specific to the Angus breed. Clinical and radiographic exams evaluating OC lesions, effusion and osteoarthritis were performed in 50 purebred bull calves at three time points between 5.8 and 21 months of age. The likelihood of OC was lower at a median age of 12.4 months (P<0.001), primarily due to resolution of distal talus changes (P<0.01). Significant associations were observed between medial malleolus lesions and effusion at median age of 7.4 months (P<0.001). This study suggests that clinical and radiographic screening performed at approximately one year of age may be beneficial in detecting tarsal OC lesions in Angus breeding herds.

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.

Prevalence and severity of osteochondrosis of the free thoracic vertebra in three modern broiler strains and the Athens Canadian Random Bred control broiler.

Osteochondrosis (OCD) results from a disturbance of endochondral ossification in articular cartilage and is an important cause of lameness in several animal species, including chickens. OCD lesions in the free thoracic vertebra (FTV) of chickens are essential to the pathogenesis of pathogenic Enterococcus cecorum. The goal of this study was to determine the prevalence of OCD in the FTV among three modern broiler chicken crosses (strains A/A, A/B, and C/C) and Athens Canadian Random Bred (ACRB) chickens, which served as the control group. The effect of sex, age, strain, body weight, and incubation temperature profile on OCD severity for each group was determined. At 2, 4, 6, and 8 weeks of age, the FTV of 10 male and 10 female birds from each strain exposed to either optimal or low-early, high-late incubation temperature profiles were collected and scored histologically for OCD lesion severity. OCD spectrum lesions were detected in >70% of all strain/sex combinations, including the ACRB controls. No association was observed between mean OCD score and broiler strain, incubation temperature profile, sex, age, or body weight. These findings indicate that OCD of the FTV is common in broiler chickens with similar prevalence observed in broilers with modern genetics and the ACRB broilers which represent 1950s broiler genetics. As the parameters examined did not have a statistical correlation with OCD, additional work is needed to understand factors that contribute to development of OCD in chickens.

Non-linear optical microscopy of cartilage canals in the distal femur of young pigs may reveal the cause of articular osteochondrosis.

BACKGROUND: Articular osteochondrosis is a common cause of leg weakness in pigs and is defined as a focal delay in the endochondral ossification of the epiphysis. The first demonstrated steps in the pathogenesis consist of loss of blood supply and subsequent chondronecrosis in the epiphyseal growth cartilage. Blood vessels in cartilage are located in cartilage canals and become incorporated into the secondary ossification centre during growth. It has been hypothesized that vascular failure occurs during this incorporation process, but it is not known what predisposes a canal to fail. To obtain new information that may reveal the cause of vascular failure, the distal femur of 4 pigs aged 82-140 days was sampled and examined by non-linear optical microscopy. This novel technique was used for its ability to reveal information about collagen by second harmonic generation and cellular morphology by two-photon-excited fluorescence in thick sections without staining. The aims were to identify morphological variations between cartilage canal segments and to examine if failed cartilage canals could be followed back to the location where the blood supply ceased. RESULTS: The cartilage canals were shown to vary in their content of collagen fibres (112/412 segments), and the second harmonic and fluorescence signals indicated a variation in the bundling of collagen fibrils (245/412 segments) and in the calcification (30/412 segments) of the adjacent cartilage matrix. Failed cartilage canals associated with chondronecrosis were shown to enter the epiphyseal growth cartilage from not only the secondary ossification centre, but also the attachment site of the caudal cruciate ligament. CONCLUSION: The variations between cartilage canal segments could potentially explain why the blood supply fails at the osteochondral junction in only a subset of the canals. Proteins linked to these variations should be examined in future genomic studies. Although incorporation can still be a major cause, it could not account for all cases of vascular failure. The role of the caudal cruciate ligament in the cause of osteochondrosis should therefore be investigated further.