Involvement of trauma in the pathogenesis of osteochondritis dissecans in swine

Limb joint soundness was examined in 40 pigs loaded into a wooden box cart and 40 control pigs not subjected to loading. On postmortem examination, eight loaded pigs showed osteochondritis dissecans in their medial humeral condyles, suggesting that porcine joints are vulnerable to osteochondral lesions when mechanically overloaded. Prevention of trauma by careful handling of pigs during penning and transportation should help to control joint lesions and lameness.

Comparison of two caudolateral approaches to the scapulohumeral joint for treatment of osteochondritis dissecans in dogs

Two caudolateral approaches to the canine scapulohumeral joint that do not require myotomy, tenotomy, or osteotomy were used to expose the humeral heads of both scapulohumeral joints in 10 clinically normal dogs. One approach (method 1) was used on the left shoulder of 5 dogs and on the right shoulder of the other 5 dogs. The other approach (method 2) was used on the opposite joints. The amount of humeral head articular cartilage that could be exposed with each approach was measured. The amount of articular cartilage exposed with method 1 was significantly greater than that exposed with method 2 (P less than 0.0001). Method 1 also provided for exposure of the caudomedial aspect of the scapulohumeral joint. Method 1 was used unilaterally in 20 dogs with osteochondritis dissecans. This approach provided excellent exposure of the humeral head and osteochondritis dissecans lesion. Of the 16 dogs that were available for follow-up evaluation, 1 developed a seroma after surgery. Other complications were not observed or reported.

The effects of beveling the margins of articular cartilage defects in immature dogs

Eight 4 month old crossbred puppies underwent surgery simulating treatment of osteochondritis dissecans. Both humeral heads were exposed by a caudal approach to the shoulder joint. In one, an 8 mm circular, full-thickness cartilage defect was created so that the remnant cartilage margin was perpendicular to the joint surface. In the other, a similar 8 mm defect was created with the chondral margins beveled at approximately 45 degrees. There was no clinical lameness in any of the dogs. At necropsy after 16 weeks, the cartilage defects with beveled edges were significantly larger (11.0 +/- 0.6 mm SD) than those with perpendicular edges (8.0 +/- 0.1 mm SD), because of the beveling (p = 0.0039). Fibrocartilage was present but did not always completely fill the defects. Articular surfaces of the glenoid cavities suffered erosion and fibrillation more frequently opposite beveled defects than opposite defects with vertical walls (p = 0.0312). This was presumably due to the larger apposing defect. It was concluded that the cartilage margins surrounding a chondral defect should not be beveled.

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.

Arthroscopic surgery for the treatment of osteochondrosis in the equine shoulder joint

Osteochondritis dissecans (OCD) and subchondral cyst-like lesions in 13 shoulders of 11 horses were treated arthroscopically by curettage and lavage. Lameness decreased in all 11 horses. Nine horses were sound, five of them athletically sound, after 5 to 20 months. Complications included the development of subchondral cyst-like lesions and signs of degenerative joint disease. Arthroscopic surgery of the equine shoulder can be done through two portals, one for the arthroscope and one for an instrument. A few hand instruments such as a probe, Ferris-Smith rongeurs, and small, large, and right-angled curettes are needed to debride most lesions. Motorized equipment can expedite the process.

Articular cartilage blood vessels in swine osteochondrosis

Perfusion studies in swine with early lesions of osteochondrosis demonstrated that lamellar areas of chondrocyte necrosis within reserve zones of growth areas occurred only in regions of nonperfused articular cartilage. Articular cartilage with a similar anatomical location was perfused in some animals. Occasionally, nonperfused articular cartilage showed vascular alterations within cartilage canals without evidence of significant perivascular or lamellar necrosis. By light microscopy, some vessels within or adjacent to nonperfused articular cartilage had normal morphology; however, ultrastructural abnormalities were found in some vessels of all cartilage canals adjacent to necrotic cartilage lamella. Minimal alterations were in the few cartilage canal vessels that appeared normal by light microscopy, and the surrounding chondrocytes showed only minimal alterations. Early cartilage canal alterations were seen in the endothelium of cartilage canal capillaries, and ultrastructural changes in these vessels were similar to those described with experimentally induced, direct vascular injury. Vascular injury was followed by leakage of plasma and cells into the interstitial space of the cartilage canal. Necrosis of the vessel wall and interstitial tissue caused the cartilage canals to appear empty or to be filled with fibrin-like material. Although the vascular changes could be considered as part of the normal process of cartilage maturation and cartilage canal chondrification, observations suggest that in domestic swine the attendant cartilage necrosis and chondrolysis is exuberant. It is suggested that alterations in cartilage canal vessels play a major role in the pathogenesis of articular cartilage lesions that are found in osteochondrosis of swine.

Effect of diet on longitudinal bone growth and osteochondrosis in swine

Weanling gilts were fed either a 12% or 16% protein diet for 10 weeks. Animals fed the 12% protein diet had reduced body weights and reduced longitudinal bone growth as measured in the distal radial growth plate. There was no difference in the growth plate widths between the two animal groups, but there was a significant reduction in the daily rate of cell production in the proliferative zone of animals fed the 12% protein diet. No effect of diet on the rate of expansion of the epiphysis at the articular-epiphyseal junction of the distal femur or humerus could be detected. All animals in both groups had morphologic cartilage lesions consistent with early changes associated with osteochondrosis (OCD), and there was no difference in the lesion morphology between the dietary groups. Areas of disorderly endochondral ossification in the radial growth plate were associated with perpendicular growth cartilage infractions. Growth plate lesions were characterized by increased widths of the maturing cartilage zone without increased width of the proliferative zone or an increase in the daily rate of cell production. Focal growth plate lesions developed because of a transitory inhibition of cartilage mineralization and resorption. Disorderly foci of endochondral ossification beneath articular cartilage were characterized by an area of chondrocyte necrosis which prevented normal cartilage matrix mineralization. Lamellae of cartilage necrosis were also present within the reserve zone of the articular cartilage. These were associated with abnormalities of the cartilage canal vessels, and chondrocyte necrosis was considered to precede degenerative changes in articular cartilage matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic and surgical arthroscopy of the equine shoulder joint

An arthroscopic technique for examination and surgical treatment of conditions of the shoulder joint was evaluated in eight normal horses and two horses with osteochondrosis lesions. A single arthroscope entry point caudal to the infraspinatus tendon allowed inspection of the cranial, lateral, and caudal surfaces of the shoulder joint. With the humeral head and glenoid cavity distracted by a curved forceps, the entire cartilage surface of the shoulder could be examined. The caudomedial portion of the humeral head was seen better with a 70 degree angled arthroscope. Instruments for intra-articular manipulation were introduced through a separate skin incision 2 to 4 cm caudal to the arthroscope entry point. Two horses with osteochondrosis lesions of the shoulder were examined arthroscopically and debrided with instrument triangulation. Five normal horses and both horses with osteochondrosis lesions were euthanized immediately after the procedure and a necropsy was performed. Minor iatrogenic damage to the cartilage surfaces and joint capsule resulted from the technique. Three horses recovered from anesthesia and were killed 3, 30, or 60 days after surgery. Subcutaneous fluid that accumulated during surgery had resorbed by 3 days and lameness was evident for 12 to 24 hours. Gross examination and histopathologic findings of specimens collected at 30 and 60 days showed several small nonhealing partial-thickness cartilage defects attributed to instrument insertion. Arthroscopy is a satisfactory method to examine the joint surfaces and to evaluate and treat osteochondrosis lesions of the shoulder joint in horses.

Acetabular osteochondrosis dissecans in a foal

Osteochondrosis affecting the acetabula in horses is rarely reported. Osteochondrosis dissecans in foals only a few weeks old is also an uncommon finding. Lesions compatible with osteochondrosis dissecans in the acetabulum were found to be the cause of a chronic coxofemoral lameness in a 3-week-old Arabian filly. The history, physical examination findings, joint fluid analysis, gross pathologic and histopathologic findings are described.

Early changes of osteochondrosis in medial femoral condyles from rats

Osteochondrosis developed from the early growing process of articular cartilage at the caudal-central region of the medial femoral condyle in rats. Articular cartilage was thick at the region. Mineralization of the matrix in the thick deep zone was incomplete and major parts remained unmineralized. Cavity formation in the mineralized matrix resulting in osteochondrotic lesions was present in the deep zone at 6 weeks of age and was followed by an appearance of viable chondrocytes around it. Osteochondrotic lesions were present from the age of 10 weeks for females and 12 weeks for males. Cavities were expanded and increased in number, and eosinophilic necrotic foci were additionally seen. These changes were extended throughout the deep zone, and viable chondrocytes were also increased in number. The thick deep zone was retained and had no detectable invasions of blood vessels from the subchondral bone. At 20 weeks of age, necrotic areas containing large clefts were present in the basal layer of the thick deep zone and fibrotic lesions were seen beneath them. In normal cases, invasions of blood vessels were seen in the basal layer of the deep zone and also in the cavities of the cartilage; the deep zone was markedly thinned at 20 weeks of age.

Osteochondrosis-like lesion of the anconeal process in two horses

A suspected lesion of osteochondrosis dissecans involving the anconeal process of the humeroradial joint (elbow) was found in 2 horses. In horse 1, the lesion was found during routine lameness examination, during which alleviation of the lameness was achieved after intra-articular anesthesia of the elbow. In horse 2, the lesion was found at necropsy. Horse 1 responded satisfactorily to intra-articular treatment with hyaluronic acid. Both horses also had other joints affected with osteochondrosis dissecans.

Observation on the development of osteochondrosis in young rats

A histopathological study on the development of spontaneous osteochondrosis in the humeral head and medial femoral condyle of rats (6-20 weeks old) was carried out. Findings were classified into three types: normal, transitional and osteochondrotic. In the normal type, the articular cartilage at the caudal region of the humeral head and medial femoral condyle was significantly thinned between 6 and 10 weeks of age (generally the caudal region was thicker than elsewhere at all ages). In the transitional type, the thinning of the cartilage was delayed. In the third type, osteochondrotic lesions were detected in the humeral head from 6 weeks of age and in the medial femoral condyle from 10 weeks of age. The thickness of the cartilage had slightly decreased or had not changed at 20 weeks of age. In the early stages, viable chondrocytes and small destructive foci of cartilage were observed in the basal layer of the thick deep zone. These cells were present in pairs or clusters surrounded by matrix in the large lacunae. Cells and destructive foci were also seen in the surface layer of the deep zone as the rats aged. In the advanced stage, a necrotic area or cleft was formed in the basal layer of the articular cartilage and fibrosis was observed in the subchondral bone.

Ultrastructural histochemical evaluation of growth plate cartilage matrix from healthy and osteochondritic swine

A contributing factor to the lack of understanding the cause of osteochondritic syndromes has been incomplete knowledge of the morphology of lesions in subclinical stages of the disease. In osteochondritic growth plate cartilage from growing swine, the morphology of the pericellular matrix surrounding hypertrophic zone chondrocytes is abnormal and is characteristic of a matrix in which the ordered interactions of matrix macromolecules with each other and with the plasma membrane have been altered. In the present study, ultrastructural histochemical techniques were used to analyze the nature of macromolecular interactions in the pericellular matrix in normal growth plate cartilage, and selective enzyme digestions of normal growth plate cartilage were used to simulate the morphology found in osteochondritic lesions. Results showed that a pericellular macromolecular material which was both ferrocyanide positive and trypsin sensitive was essential for stabilizing the cell membrane/pericellular interface in normal growth plates. The highly variable morphology of this same material in osteochondritic lesions was simulated by hyaluronidase digestion. Since similar pericellular matrix abnormalities have not been described in other diseases of growth plate cartilage, they may represent a matrix abnormality unique to the vascularization failure of osteochondritic syndromes. Our ability to simulate the ultrastructural morphology of subclinical osteochondritic lesions enhances the potential for understanding the macromolecular changes found in the pericellular matrix of osteochondritic cartilage. Based on these results, a new hypothesis is presented for the early sequence of events in the pathogenesis of osteochondrosis.

The effect of replacement of 0.30% sodium chloride by 0.43% sodium bicarbonate in rations of fattening pigs on leg weakness, osteochondrosis and growth

The effect of replacing dietary sodium chloride by sodium bicarbonate on leg weakness, osteochondrosis and growth in young fattening pigs was studied in two experiments using 104 and 126 animals. The experimental pigs were fed 0.43% dietary sodium bicarbonate, which replaced the sodium chloride (0.30%), was present in the diets of the control groups. It was found that the clinical symptoms of leg weakness could be improved significantly in the experimental group which received bicarbonate. No positive effects on osteochondrosis, however, could be shown. The treated animals even tended to have more severe osteochondral lesions. Reasons for the negative tendency are discussed. Daily weight gain and food conversion were not influenced by the experimental bicarbonate diet excluding a chloride deficiency. Differences in carcass grading were not significant, although barrows fed the NaHCO3-containing diet tended to score better, while the carcass quality of the experimental gilts was slightly less in comparison to the control animals.

Windswept deformities in poultry

"Windswept deformities", involving valgus angulation of one intertarsal joint and varus angulation in the contralateral limb, were identified in 75 of 120 turkeys and 24 of 120 broiler fowls which had been culled because of lameness, so that windswept limb angulation was more common in turkeys than broilers. A proportion of cases can be more accurately described as unilateral intertarsal varus deformities with physiological valgus angulation of the contralateral limb. In other cases, marked angulation of one limb probably results from adoption of an altered posture secondary to deformity of the contralateral limb. No correlation was found between abnormal bone torsion, limb angulation and dyschondroplastic lesions. In broilers, almost 70 per cent of windswept limbs with 20 degrees or more intertarsal angulation showed physeal disturbance in the distal tibiotarsus or proximal transometatarsus or both. This finding supports the concept that windswept deformities are commonly associated with physeal lesions but whether the two conditions are causally related is uncertain.

The ultrastructure of osteochondrosis of the articular-epiphyseal cartilage complex in growing swine

Osteochondrosis of the articular-epiphyseal cartilage complex (A-E complex) is a significant clinical disease in swine. It has been suggested that osteochondrosis is the underlying cause of osteochondritis dissecans in humans. The purpose of this investigation was to characterize the ultrastructural changes in the earliest macroscopically visible lesion of the epiphyseal cartilage in osteochondrosis of the A-E complex in swine. Osteochondritic epiphyseal cartilage from the distal femora and humeri of growing crossbred boars was collected, embedded in plastic, and studied light and electron microscopically. The predominant lesion was chondronecrosis, characterized by chondrocyte death and loss of matrical proteoglycan. Transition from normal to abnormal cartilage was abrupt. Lipid accumulated in chondrocytes within and adjacent to lesions, but not in chondrocytes distant from lesions. Intracellular lipid accumulation was an important feature of the lesion and may play a role in its initiation. It is hypothesized that intracellular lipid accumulation results from hypoxia/anoxia and may precede matrix degeneration, which precedes cell death.

Osteochondritis dissecans of the femoral head of a Pekingese

An 8-month-old male Pekingese was admitted with a 1-month history of right hindlimb lameness and crepitation in the right coxofemoral joint. There was radiographic evidence of a focus of subchondral osteolysis of the right femoral head. The tentative diagnosis was avascular necrosis of the femoral head. The problem was corrected by femoral head ostectomy. Gross and microscopic examination of the femoral head resulted in a diagnosis of osteochondritis dissecans. Osteochondritis dissecans is an uncommon diagnosis both in small breeds of dogs and in the coxofemoral joint.

Osteochondrosis, dyschondroplasia, and osteomyelitis causing femoral head necrosis in turkeys

Femoral head necrosis is a term that has been used, frequently inappropriately, to describe a variety of lesions in the head and proximal femur of poultry. In a survey of causes of lameness in a group of 18,000 tom turkeys, examination of femurs from lame 16-to-30-week-old heavy male turkeys with femoral head necrosis revealed that the lesions could be placed in one of three categories: degeneration of articular or growth plate cartilage and bone, with separation usually between the growth plate and metaphysial bone; avascular necrosis with sequestration and degeneration of an abnormal mass of prehypertrophying cartilage (dyschondroplastic cartilage), with spontaneous fracture and collapse of the femoral head or fracture through the metaphyses or neck of the femur; and osteomyelitis, with necrosis usually beneath the growth plate in the metaphyses. The second and third categories of lesion were frequently found in the proximal tibia as well, so the term long-bone necrosis would be a more suitable morphologic description than femoral head necrosis.

Dyschondroplasia/osteochondrosis of the femoral trochanter in the fowl

Of 104 lame broilers, 12 birds with femoral trochanteric abnormalities were identified by post-mortem and radiographic examination. Defects occurred in ossification of either the trochanteric zenith or its medial aspect. Lesions were identified as dyschondroplasia, osteochondrosis or osteochondrosis dissecans affecting the articular surface of the femoral trochanter. In the absence of concomitant musculoskeletal disease, degrees of lameness can be attributed to trochanteric lesions. Breaches in the medial trochanteric bone plate permit granulation tissue repair of the articular surface. This repair process, however, did not compensate for the loss of articular surface contour and the junction of reparative and normal tissue may be prone to subsequent degeneration.