An ultrastructural analysis of osteochondritic growth plate cartilage in growing swine

In growing swine, ossification failure due to osteochondrosis has an incidence of nearly 100% in the distal ulna of animals at six months of age, yet the etiology of the disease is understood poorly. In this study, the ultrastructure of the chondrocyte and its pericellular matrix is analyzed in normal growth plates and in growth plates with lesions characteristic of osteochondrosis using aldehyde primary fixatives and osmium-ferrocyanide as the secondary fixative. Chondrocytes in lesion areas fail to undergo normal hypertrophic cell maturation, and they have an accumulation of rough endoplasmic reticulum, lipid droplets and mitochondria. These morphological changes are interpreted to be both variable and nonspecific for osteochondrosis. Within the pericellular matrix of chondrocytes from lesion areas, the most striking abnormality is the presence of a highly condensed matrix with an accumulation of large, irregularly shaped deposits of electron dense material. These morphological alterations are characteristic of a matrix which either is not secreted normally, or in which the highly ordered interactions of diverse macromolecules has been lost. These pericellular matrix changes have not been described in other diseases of growing cartilage. They may be significant in the failure of metaphyseal vascular penetration of the pericellular matrix which is characteristic of osteochondrosis.     

Identification of infrared absorption spectral characteristics of synovial fluid of horses with osteochondrosis of the tarsocrural joint

OBJECTIVE: To determine the feasibility of the use of Fourier-transform infrared (FTIR) spectroscopy within the midinfrared range to differentiate synovial fluid samples of joints with osteochondrosis from those of control samples. ANIMALS: 33 horses with osteochondrosis of the tarsocrural joint and 31 horses free of tarsocrural joint disease. PROCEDURES: FTIR spectroscopy of synovial fluid was used. Sixty-four synovial fluid samples from the tarsocrural joint were collected. Of these, 33 samples were from horses with radiographic evidence of osteochondrosis of the tarsocrural joint and 31 from control joints. Disease-associated features within infrared spectra of synovial fluid were statistically selected for spectral classification, and the variables identified were used in a classification model. Linear discriminant analysis and leave-one-out cross-validation were used to develop a classifier to identify joints with osteochondrosis. RESULTS: 12 significant subregions were identified that met the selection criteria. The stepwise discriminant procedure resulted in the final selection of 6 optimal regions that most contributed to the discriminatory power of the classification algorithm. Infrared spectra derived from synovial fluid of joints with osteochondrosis were differentiated from the control samples with accuracy of 77% (81% specificity and 73% sensitivity). CONCLUSIONS AND CLINICAL RELEVANCE: The disease-associated characteristics of infrared spectra of synovial fluid from joints with osteochondrosis may be exploited via appropriate feature selection and classification algorithms to differentiate joints with osteochondrosis from those of control joints. Further study with larger sample size including age-, breed-, and sex-matched control horses would further validate the clinical value of infrared spectroscopy for the diagnosis of osteochondrosis in horses.     

Blood flow distribution in hind limb bones and joint cartilage from young growing pigs.

Blood flow distribution was studied in hind limb bones and joint cartilage from four ten week old and four 20 week old pigs using 141Ce-microspheres. In general, blood flow rate was greater in the epiphyseal and metaphyseal cancellous bone than in the cortical bone and joint cartilage. In the epiphyseal cancellous bone, blood flow rate was three to tenfold greater (P less than 0.01) in the surface 2 mm layer than in the remaining deeper bone in all femoral and tibial samples examined. In the joint cartilage, blood flow rate in the femoral condyle was greater (P less than 0.05) than in the proximal femur, patella, central tarsus and metatarsus in ten week old pigs, and was greater (P less than 0.05) in the femoral condyle than in the patella and metatarsus in 20 week old pigs. A significant (P less than 0.05) age-associated decrease in the rate of blood flow was observed in the femoral, patellar and metatarsal cartilage. Within the femoral condyle, no differences in blood flow were found between areas associated with relatively high versus relatively low incidences of osteochondrosis.     

FRAGMENTATION OF THE MEDIAL MALLEOLUS OF DOGS WITH AND WITHOUT TARSAL OSTEOCHONDROSIS

Fragmentation of the medial malleolus of the tibia was found radiographically in 5 canine tarsi which did not have evidence of osteochondrosis of the medial trochlear ridge. An additional 5 tarsi were found where both medial malleolar fragmentation and osteochondrosis of the medial trochlear ridge were present. Radiographic evidence of degenerative joint disease was present in 3 of 5 dogs with medial malleolar fragmentation alone, and 5 of 5 dogs with medial malleolar fragmentation and medial trochlear ridge osteochondrosis. Eight of the 9 dogs were Rottweilers. Considering the sites of occurrence of osteochondrosis in other species, the authors propose that medial malleolar fragmentation could be secondary to osteochondrosis of the medial malleolus. Osteochondrosis of the medial malleolus has not been previously reported in dogs. Histological examination of the medial malleolar fragmentation was unavailable because surgery was not performed, therefore the hypothesis that the medial malleolar fragmentation is due to osteochondrosis was not proven.     

Evaluation of the influences of exercise, birth date, and osteochondrosis on plasma bone marker concentrations in Hanoverian Warmblood foals

OBJECTIVE: To determine whether plasma concentrations of bone turnover markers in growing Hanoverian foals are influenced by age, housing conditions, or osteochondrosis. ANIMALS: 165 healthy foals and 119 foals with osteochondrosis. PROCEDURES: Foals were allocated according to birth date and housing management into groups of early-born (born before March 31, 2001; n = 154 foals, 88 of which were healthy and 66 of which had osteochondrosis) and late-born (born after March 31, 2001; 130 foals, 77 of which were healthy and 53 of which had osteochondrosis) foals. Plasma osteocalcin and carboxyterminal propeptide of type I collagen concentrations were analyzed as markers of bone formation, and carboxyterminal telopeptide of type I collagen concentration was analyzed as a marker of bone resorption. Foals underwent radiographic evaluation to screen for osteochondrosis. RESULTS: Plasma concentrations of osteocalcin, carboxyterminal propeptide of type I collagen, and carboxyterminal telopeptide of type I collagen decreased with age, but these changes were more distinct in late-born foals than in early-born foals. Neither sex nor predisposition to develop osteochondrosis affected the pattern of bone marker changes in either group. CONCLUSIONS AND CLINICAL RELEVANCE: An age-related decrease in concentrations of bone markers was seen during the first 200 days of life. Changes in bone marker concentrations were similar for foals with osteochondrosis and healthy foals. The correlation between the decrease in bone marker concentration and date of birth indicates that there are differences in skeletal development between early- and late-born foals.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis.     

Frequency and severity of osteochondrosis in horses with cervical stenotic myelopathy

We compared the frequency and severity of osteochondrosis lesions in young Thoroughbred horses with cervical stenotic myelopathy (CSM) vs that in clinically normal Thoroughbreds of the same age. All lesions of the cervical vertebrae and appendicular skeleton were classified histologically as osteochondrosis or nonosteochondrosis and were measured for severity. Minimal sagittal diameter was significantly smaller in horses with CSM from C2 through C6; no difference was detected at C7. Severity of cervical vertebral osteochondrosis was greater in the horses with CSM, however frequency was not different. Frequency and severity of nonosteochondrosis lesions were not different in cervical vertebrae or appendicular skeleton. Frequency and severity of appendicular skeleton osteochondrosis lesions were both greater in horses with CSM. Osteochondrosis and nonosteochondrosis lesions were more severe on facets at sites of compression than on facets at noncompressed sites in horses with CSM. However, compression was also observed at sites with no articular facet lesions. The association of widespread osteochondrosis and spinal canal narrowing with CSM suggests CSM may represent a systemic failure in the development or maturation of cartilage and bone.     

General and local [corrected] aetiologic factors in canine osteochondrosis

Observations based on necropsy findings in 89 dogs with osteochondrosis are presented. Osteochondrosis was most common in the elbow joint, followed by the shoulder joint, the stifle and the hock joint. There were 59 male and 30 female dogs, and the mean age was 2 years. The high frequency of bilateral lesions and the occurrence of osteochondrosis in more than one pair of joints in 25 of the 89 dogs indicates that general factors are important. The various manifestations of osteochondrosis and their frequency are reported. Various local factors believed to be important for the occurrence of the lesions within the joints are also considered.     

Avulsion of the tibial tuberosity in a litter of greyhound puppies

Avulslon of the tibial tuberosity was dlagnosed In six of seven greyhound ilttermates aged flve and a half months. The puppies showed hindlimb lameness of varying severity. Radiological assessment of affected stifle joints revealed partial or complete avulsion of the tlblal tuberoslties. In four puppies the lesions were bliaterai. Euthanasia of the two most severely affected puppies performed; the changes observed on histopathological examination of their cranioproximal tibiae suggested that the underlying lesion was that of osteochondrosis. A heredltary predisposition In greyhounds to osteochondrosis of the physis between the apophysis and the cranioproximal tibia1 dlaphysis Is postulated.     

Osteochondrosis — An international problem for the horse industry

Osteochondrosis is one of the most important skeletalproblems affecting young horses and is one of the conditions included in the syndrome of developmental orthopedic disease. It occurs worldwide in many different breeds and its incidence appears to be steadily increasing. The primary lesion of osteochondrosis is attributed to focal damage of endochondral ossification. When occurring in the articular/epiphyseal cartilage complex, there may be bone formation within the retained cartilage, resulting in “bony fragments.” These are often seen in the tarsocrural articulation on the cranial aspect of the tibia. Focal retention of necrotic cartilage into the subchondral bone may eventually lead to cleft formation resulting in osteochondrosis dissecans. Other lesions associated with osteochondrosis are subchondral cysts, fractures and osteoarthrosis.The definitive cause of osteochondrosis is unknown,but there is evidence that it is the response in growth cartilage to a number of different challenges. It appears to be multifactorial in origin, involving heredity, growth rate, body size, nutrition, mineral imbalance, endocrinological dysfunction and biomechanical trauma. Recent studies have shown cases of osteochondrosis to be preceded by radiographically detectable disturbances of endochondral ossification during the first three months of life. This early appearance of disturbed ossification necessitates further studies into the importance of nutrition/management of the pregnant and lactating mare. Whether these early disturbances will lead to fully developed osteochondrosis or if they will recede obviously depends on a number of factors such as nutrition and exercise. High energy diets have been shown in weaning foals to consistently produce lesions of osteochondrosis. If, however, foals fed a high energy diet are subjected to forced exercise, the incidence of osteochondrosis is reduced dramatically.The prevention of osteochondrosis must rate as a highpriority for the horse industry, but to achieve this more data on the mechanisms of endochondral ossification and how this process is influenced by different intrinsic and environmental factors are required. Recent research into osteochondrosis has involved studies of chondrocyte metabolism in growth cartilage, the influence of growth factors, the extent of degradation of extracellular matrix and endochondral ossification.     

General and aetiologic factors in canine osteochondrosis

Summary

Observations based on necropsy findings in 89 dogs with osteochondrosis are presented. Osteochondrosis was most common in the elbow joint, followed by the shoulder joint, the stifle and the hock joint. There were 59 male and 30 female dogs, and the mean age was 2 years. The high frequency of bilateral lesions and the occurrence of osteochondrosis in more than one pair of joints in 25 of the 89 dogs indicates that general factors are important.

The various manifestations of osteochondrosis and their frequency are reported. Various local factors believed to be important for the occurrence of the lesions within the joints are also considered.     

Subchondral cystic lesions of the proximal extremity of the tibia in horses: 12 cases (1983-2000)

OBJECTIVE: To determine clinical and radiographic features of subchondral cystic lesions (SCL) of the proximal extremity of the tibia in horses that could be used to classify these lesions as being related to osteochondrosis or osteoarthritis and to evaluate results of surgical debridement. DESIGN: Retrospective study. ANIMALS: 12 horses with 14 SCL. PROCEDURE: Medical records and radiographs obtained before and after treatment were reviewed. RESULTS: In 6 young horses (8 lesions), SCL were considered to be related to osteochondrosis; all involved the lateral tibial condyle. The remaining 6 horses were mature and had radiographic evidence of osteoarthritis in addition to SCL. Arthroscopic debridement was performed in 4 horses in which lesions were considered to be a result of osteochondrosis and in 3 horses with osteoarthritis. Three horses in which SCL were considered to be a result of osteochondrosis performed athletically after debridement. Two horses with moderate osteoarthritis returned to work after arthroscopic debridement but at a lower level of athletic performance. One horse with SCL related to osteochondrosis responded to medical treatment and went on to race. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that arthroscopic debridement of SCL is feasible in horses in which lesions involve the cranial portion of the lateral or medial tibial condyle, and that treated horses may be able to perform athletically.     

Clinical features and heritability of osteochondrosis of the elbow in labrador retrievers

The occurrence of osteochondrosis in a breeding colony of labrador retrievers during an 11-year period was investigated. Management practices and environmental factors were similar for all dogs. In 1247 progeny, elbow lameness was recorded in 259 dogs (21 per cent) and lesions of osteochondrosis on the coronoid process and, or, medial condyle of the humerus were confirmed in 189 dogs (15 per cent). None of 39 labrador crossbred dogs were affected. The incidence in progeny varied between different sires and dams and was associated with the severity of radiographic evidence of elbow arthritis in sires and dams with dams contributing significantly more than sires, suggesting a ‘maternal’ effect.     

Use of histochemical techniques in the characterisation of osteochondroses affecting pigs

Growth cartilages with dyschondroplastic foci (osteochondrosis) or areas of chondrolysis were selected from the ribs and bones of the appendicular skeleton of 132 commercial pigs euthanased between one and 169 days old or at a liveweight of 100 kg. Histochemical staining techniques that identified proteoglycans, collagen and deposits of calcium enhanced the visualisation of the lesions, were valuable for recognising the distribution of lesions, and helped to elucidate the development of the lesions. On the basis of the histochemical and morphological differences, it was considered that the lesions associated with growth plates and the lesions associated with articular-epiphyseal cartilage complexes should be considered as different entities. Lesions were identified in the articular-epiphyseal cartilage complexes of pigs at 15 days old, earlier than has been reported previously. Toluidine blue and safranin O were more useful than alcian blue and, in terms of staining intensity, toluidine blue gave more consistent results than safranin O.     

Osteochondrosis in the horse--searching for the key to pathogenesis

This paper reviews current developments in equine osteochondrosis complex and the clinical syndromes associated with it. Although the primary lesion has been defined as a failure of endochondral ossification, its definitive cause is unknown and appears to involve heredity, growth rate, nutrition, mineral imbalance, endocrinological dysfunction and biomechanical trauma. Despite the international importance of osteochondrosis in horses, surprisingly few controlled investigations have been performed on its pathogenesis. The studies that have been conducted suggest that local effects on differentiating growth cartilage are the key to a more complete understanding of the problem. Gaps in the current knowledge include in-depth understanding of the life cycle of chondrocytes in growth cartilage, the process of mineralisation and the use of a standard experimental model for the induction of osteochondrosis. The ultimate goal of osteochondrosis research must be to prevent or reduce the incidence of the condition in horses.     

Radiological investigations of osteochondrosis dissecans in Standardbred Trotters and Swedish Warmblood horses

A total of 106 Standardbred Trotters and 27 Swedish Warmblood horses, with a radiological diagnosis of osteochondrosis dissecans, were studied over a six year period. The majority were young horses. No statistical difference in frequency between the sexes was demonstrated. In both breeds osteochondrosis was most common in the hock joints, the site of predilection being the distal dorsal tip of the intermediate tibial ridge. On radiographs the lesions of the hock joints were graded on a scale from 0 to 5 according to size, number and localisation of defects and visible loose bodies. The sizes of the loose bodies estimated radiologically were fairly closely correlated with those found at surgery or autopsy.     

Early lesions of articular osteochondrosis in the distal femur of foals

Failure of the cartilage canal blood supply to epiphyseal growth cartilage has been implicated in the pathogenesis of articular osteochondrosis in horses and other animal species. In a previous study of the developmental pattern of the blood supply in the tarsus of foals, early lesions of osteochondrosis were consistently found in regions where the cartilage canal vessels traversed the chondro-osseous junction. The developmental pattern of blood vessels has also been described in the distal femoral epiphysis; however, the group of foals examined in that study did not have lesions of osteochondrosis in this location. Therefore, the relationship between the occurrence of early lesions of osteochondrosis and the developmental pattern of the blood supply to epiphyseal growth cartilage in this site in foals has not been examined. Distal femora were collected from 30 fetuses and foals (up to 11 months old) submitted for postmortem examination. Sections from the lateral trochlear ridge and medial femoral condyle of both hind limbs were examined histologically. Sixteen cartilage lesions were found in 7 of the 30 fetuses and foals. All lesions contained evidence of cartilage canal necrosis and ischemic chondronecrosis. The lesions were located in regions where cartilage canal vessels traversed the chondro-osseous junction, as previously observed in the tarsus. The location and morphology of lesions indicated that a subclinical stage of ischemic chondronecrosis existed that preceded and predisposed to the development of osteochondrosis dissecans and subchondral bone cysts.     

Osteopetrosis in a neonatal donkey

Osteopetrosis is a rare disorder characterised by a defect in osteoclastic bone resorption. This report describes osteopetrosis in a neonatal donkey that suffered a displaced tibial fracture. Radiographic examination identified generalised reduction in medullary cavity size, thickened mid‐diaphyseal cortices and conical metaphyseal bone extending toward the mid‐diaphysis of long bones. Postmortem examination identified additional fractures and brittle bones. Histologically, osteoclasts were absent in multiple bone sections. Diaphyseal cortices consisted of concentric bone lamellae with marrow tissue infiltration. Large wedges of secondary spongiosa extended from the metaphyseal growth plate. Clinical and histopathological features were similar to an osteoclast‐deficient, autosomal recessive form of osteopetrosis in humans.