Complications of articular lag screw fixation of femoral capital epiphyseal separations

Four femoral capital epiphyseal separations in three immature dogs were repaired using an articular lag screw procedure. Two millimetre cortical screws were inserted from the articular surface across the fracture site in lag fashion. The screw heads were countersunk below the surface of the articular cartilage to prevent abrasion of the apposing articular surface. Marked osteolysis of the femoral neck was noted between four and eight weeks postoperatively in all cases, and excision of the femoral head and neck was carried out in two cases at six and eight weeks postoperatively. It is believed that the surgery failed because of iatrogenic vascular insult and the development of coxofemoral instability.     

Consequences of capital femoral dyschondroplasia in young adult and skeletally mature broilers

Radiographs revealed defective endochondral ossification in proximal femora of 52 lame broilers. Cartilage retention either involved epiphyseal cartilage close to the articular surface or growth plate cartilage (dyschondroplasia). In at least seven birds proximal femoral lesions were the only abnormalities detected which could have caused lameness. In cases of moderate or severe cartilage retention, fracture lines traversed necrotic cartilage to undermine part or all of the femoral head. Evidence of reparative fibrosis was seen with augmentation of metaphyseal trabeculae by woven bone apposition. Foveal blood vessels aided repair by re-establishing a new ossification centre but in many cases attempts at repair were inadequate.     

Femoral neck fractures and capital epiphyseal separations in cats

In a retrospective study, 47 fractures of the femoral neck and 17 capital epiphyseal separations were recorded in a total of 62 animals over a 12-year period. It was found that cats sustain femoral neck fractures more often than capital epiphyseal separations. Until cats are six months old the vast majority of lesions in the proximal femur are fractures of the neck. Between the ages of six and 12 months both lesions are equally represented. After 12 months of age no capital epiphyseal separations occur and the incidence of femoral neck fractures diminishes appreciably. If left untreated, an acceptable clinical result can be obtained in both femoral neck fractures and capital epiphyseal separations, although the best functional result is achieved in femoral neck fractures. In the present study, spontaneous healing was seen only in femoral neck fractures in cats younger than three months. All cats with capital epiphyseal separations developed hypertrophic pseudoarthrosis.     

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.     

Three-dimensional culture of feline articular chondrocytes in alginate microspheres

Chondrocytes isolated from proximal femoral articular cartilage from 3 adult cat cadavers were expanded in monolayer culture and subsequently cultured in alginate microspheres for 24 days. Cell proliferation and production of proteoglycans in alginate microspheres were observed during day 18 and 24. Quantification of chondroitin sulfates (CS) by capillary electrophoresis revealed that cultured chondrocytes synthesized CS6 but not CS4. Three-dimensional culture using alginate microspheres is a useful in vitro technique to study proliferation and metabolism of chondrocytes; however, further modifications are needed to apply the technique to feline articular chondrocytes.     

Capital femoral epiphyseal infarction in skeletally immature broilers

Varying degrees of capital femoral epiphyseal infarction have been identified in broiler chickens. The extent of vascular occlusion was more extensive than observed in capital femoral dyschondroplasia and growth plate cartilage retention was not a constant finding. Epiphyseal vascular occlusion resulted in growth plate cartilage necrosis. It is suggested that proliferating chondrocyte death and matrix disruption would predispose to epiphyseolysis. Similarities between avian capital femoral epiphyseal infarction and Legg-Calve-Perthes disease have been noted.     

Cartilage thickness measurement in foals

The talus and proximal and distal epiphysis of the humerus, radius, femur, tibia and distal metacarpus of 20 foals aged 0 to 150 days were obtained at necropsy and sawn sagittally into slabs 4 to 8 mm thick. The thickness of the cartilage (articular cartilage and unossified epiphyseal cartilage) was measured in three to five places in each slab, using a sliding calliper. In most epiphyses, the site, or sites, of thickest cartilage was constant in all foals examined. The difference between thickest and thinnest cartilage within one epiphysis was greatest in distal femora and least in distal metacarpi. The sites of most common occurrence of osteochondrosis dissecans in tali and proximal humeri concurred with the site of thickest cartilage in these bones. The most common site of equine osteochondrosis, the middle and distal thirds of the lateral trochlear ridge of femora, is not the location of thickest cartilage in this epiphysis. Haematological epiphyseal osteomyelitis in foals occurs most frequently in the areas where cartilage thickness is greatest in the medial femoral condyle, talus and distal radius.     

The zonal distributions of alkaline phosphatase, adenosine triphosphatase, laminin, fibronectin and chondroitin 4-sulphate in growing rat humerus proximal epiphyseal cartilage: a histochemical and an immunohistochemical study

Although there are many studies about epiphyseal cartilage extracellular matrix (ECM) macromolecules in bone formation, studies of their distribution and role in the mineralization of these components in growing rat humerus proximal epiphyseal cartilage have not been sufficiently detailed. The aim of this study was to determine the distributions of alkaline phosphatase (ALP), adenosine triphosphatase (ATPase), laminin, fibronectin and chondroitin 4-sulphate in growing rat humerus proximal epiphyseal cartilage. The rats were killed by cervical dislocation, and the humeri were removed, sectioned (6 and 10 microm) on a cryotome or paraffin microtome, and stained using histochemical and immunohistochemical methods. ALP and ATPase were markedly observed in the hypertrophy and calcifying cartilage. In addition, ATPase was found to be very strongly positive in the tangential zone of articular cartilage. Results of immunohistochemical staining for laminin, fibronectin and chondroitin 4-sulphate showed that the immunostaining was the heaviest in the tangential zone of articular cartilage. In growing epiphyseal plates, there were differences in the density of these macromolecules of chondrocytes as a function of the maturation process. In conclusion, these ECM macromolecules of epiphyseal cartilage may regulate the cell-cell and cell-matrix interactions as well as the matrix calcification during the ossification of epiphyseal cartilage.     

In vitro characterization of porcine juvenile articular cartilage

Dispersed cell cultures were established from the articular cartilage of the proximal portion of the humerus of young pigs. Articular and epiphyseal portions of the cartilage were separated, minced, and enzymatically dispersed, using bacterial collagenase. Morphologically, 2 cell types were observed, using phase-contrast microscopy. Smaller polygonal cells (32.5 +/- 3.5 microns diameter) containing cytoplasmic granules were found in both areas of the cartilage. In cultures from the articular region, cells grew as monolayer cultures and initially did not demonstrate contact inhibition. In cultures from the epiphyseal region, cells grew in a multilayered manner in a colonial arrangement with cells being released from the center of the colony into the culture medium. Small granular particles (0.03 to 0.08 micron diameter) were secreted by cells in both culture systems. Particle secretion was greater in epiphyseal cultures than in articular cultures with the rate decreasing as confluency was approached. These particles stained positively for lipid and alkaline phosphatase. Acridine orange was also incorporated into the granules. The 2nd cell type, a stellate-shaped cell (60 +/- 7.6 micron diameter), was found mainly surrounding the outside of colonial areas in epiphyseal cultures. These cells did not secrete small granular particles and stained positive for factor VIII. Evaluation of cultures by scanning and transmission electron microscopy further supported the presence of 2 cell types. With scanning electron microscopy, the smaller polygonal cell was characterized by varying sizes of blebs (0.03 to 0.1 micron diameter) associated with the cell membrane and small cytoplasmic processes projecting from the cell's surface.(ABSTRACT TRUNCATED AT 250 WORDS)     

DEVELOPING A TECHNIQUE FOR ULTRASOUND‐GUIDED INJECTION OF THE ADULT CANINE HIP

An accurate method for guiding injections into the canine hip would facilitate diagnostic localization of lameness and targeted treatments. Ultrasound‐guided hip injections are commonly used in humans and large animals. Aims of this prospective study were to describe ultrasound (US) anatomy of the adult canine hip and determine the feasibility and accuracy of intra‐articular placement of injectate using US‐guidance. Seven adult dogs were used to describe US anatomy, five dog cadavers were used to assess the feasibility of the injection technique and 11 dog cadavers were used to assess accuracy of injections. For the accuracy test, 22 joints were injected with iodinated contrast medium by three operators with different experience. With dogs in lateral recumbency, the hyperechoic femoral head surface was identified by following the femoral neck from the greater trochanter or the acetabular rim was localized by following caudally the ilium from the iliac wing.  An anechoic gap between the femoral head and acetabular surface represented the joint. The capsule was visible as a triangular echoic structure and the femoral head articular cartilage appeared as an anechoic band. The needle was inserted axial to the greater trochanter and directed in a dorsolateral–ventromedial direction toward the joint space and then pushed through the capsule. Based on postinjection radiography, accuracy was 81.8% at first attempt and 100% at second attempt. This study indicated that US‐guided injection is a feasible and accurate technique for injecting the adult canine hip. Future studies in live dogs are needed to assess safety and efficacy.     

Age related changes and osteochondrosis in swine articular and epiphyseal cartilage: light ane electron microscopy.

Age related changes and osteochondrosis in swine were studied using light microscopy and electron microscopy in articular cartilage and light microscopy and epiphyseal cartilage of swine from three days to 30 weeks of age. Thickness, cellularity and vascularity of both the epiphyseal and articular cartilage, decreased as the swine aged. Osteochondrotic changes included formation of "plugs" of cartilage indicating localized failure of ossification and separation and space formation in epiphyseal cartilage. Eosinophilic streaks and space formation in epiphyseal cartilage was observed in relation to epiphyseal separation. Electron microscopy showed a continuous fibrillar layer on the surface of the cartilage corresponding to the lamina splendens of light microscopy. This layer increased in the thickness and showed accumulation of amorphous material between the fibrils with aging. In the matrix, the orientation and distribution of the collagen fibers changed with growth and thicker fibers with clear sub banding were more common in older age groups. Also, necrotic cells, glycogen containing bodies and cellular debris were noticed in the matrix of normal cartilage in old animals. Chondrocytes in the younger cartilage showed accumulation of organelles responsible for protein synthesis; while Golgi bodies, vesicles, lysosomes, well developed foot processes and other inclusions were noticed in older cartilage. Cartilage erosions had a clumped and disrupted lamina splendens on the surface and electron lucent patches in the ground substances of the matrix and chondrocyte cytoplasm.     

Evaluation of an Interfragmentary Compression System for the Repair of Equine Femoral Capital Physeal Fractures

Femoral neck and proximal epiphyseal lengths were measured in 37 femurs from 19 cadaver foals that were 1 day to 12 months old to determine the applicability of a human interfragmentary compression system to equine femoral capital physeal fractures. Because components of the implant system are available only in fixed sizes, its use was possible in foals older than 5 weeks of age, but not in younger foals. The 135 degree angle plate conformed best to the equine femur. Femoral capital physeal fractures were created surgically and repaired with the implant system in three foals. Fracture stability was evident clinically and radiographically in all three foals until euthanasia at month 3. At necropsy, the treated femurs were 4, 8, and 27 mm shorter than their mates. Epiphyseal viability was verified in all three foals by tetracycline deposition and new appositional bone growth comparable with that in the contralateral control epiphyses. The treated capital physis was open but reduced in thickness in one foal, disorganized in one foal, and closed in one foal. Fixation by compression with the implant system resulted in stability sufficient for fracture healing and maintenance of epiphyseal viability, although it was associated with reduced longitudinal femoral growth.     

Carbonic anhydrase localization in normal and osteochondrotic joint cartilage of growing pigs.

The histochemical localization of carbonic anhydrase in the normal and osteochondrotic epiphyseal growth cartilage from 15 growing pigs (6 to 18 weeks old) was studied. All animals were clinically normal. The entire thickness of the articular-epiphyseal cartilage complex from the femoral condyles was fixed in 2% glutaraldehyde and embedded in a water-soluble glycolmethacrylate. Sections (1-2 microns) were incubated on the surface of a medium containing cobalt, phosphate, and bicarbonate. A black precipitate formed at sites of enzymatic activity. This method shows the activity of all different isoenzymes of carbonic anhydrase. The specificity was checked by adding the carbonic anhydrase inhibitor acetazolamide to the incubation medium. Osteochondrosis in the epiphyseal growth cartilage was characterized by chondronecrotic areas in resting, proliferative, hypertrophic, and calcifying regions. When the hypertrophic and calcifying regions were involved, insufficient cartilage calcification and focally impaired ossification were seen. The chondronecrotic areas were surrounded by groups of morphologically viable cells, or so-called "clusters." Carbonic anhydrase was present in chondrocytes of hypertrophic and calcifying regions of the normal growth cartilage and in osteoclasts and erythrocytes. No evidence of carbonic anhydrase activity was found in the articular cartilage or in the resting region of normal growth cartilage in any of the pigs. No enzyme activity was found in the osteochondrotic cartilage, either in clusters or dead cells. The lack of carbonic anhydrase in the osteochondrotic cartilage demonstrated in this study may result in an inability to produce the alkaline matrix necessary for calcification and could be one reason for the insufficient calcification typical of this cartilage.     

Excision arthroplasty of the femoral head and neck

An abnormality of the coxofemoral joint is recognized when the articular cartilage sliding interface between the femoral head and the acetabulum is interrupted. The article considers the pathologic conditions that may affect the normal coxofemoral articulation and are responsive to excision arthroplasty. Techniques of excision arthroplasty and the biceps femoris muscle sling technique are described.     

Haematogenous osteomyelitis in cattle

The examination of 70 cattle with haematogenous osteomyelitis resulted in the classification of the bone lesions into two main groups: the physeal type, in which an infection, usually of metaphyseal bone, originated at or near the growth plate, usually in the distal metacarpus, metatarsus, radius or tibia, and the epiphyseal type, in which an infection originated near the junction of the subchondral bone and the immature epiphyseal joint cartilage, most often in the distal femoral condyle epiphysis, the patella and the distal radius. Combinations of physeal and epiphyseal defects and even diaphyseal involvement were occasionally seen. Epiphyseal osteomyelitis was mostly caused by salmonella infection, physeal by Corynebacterium pyogenes, salmonella and other bacteria. The salmonella affected animals were with one exception less than 12 weeks old and the majority had had some previous illness or came from a problem herd. The C pyogenes affected calves were in almost all cases more than six months old. The prognosis of the metaphyseal infection was in general satisfactory, and surgical intervention (osteotomy or sequestrectomy) was often required. The prognosis of the epiphyseal type was grave but two of the three animals in which physeal and epiphyseal defects were accompanied by diaphyseal lesions recovered.     

Surgical remodelling of the femoral trochlea: an experimental study.

Surgical deepening of the groove in the femoral trochlea is a technique commonly employed in the correction of patellar dislocation in dogs. In order to discover how this deep articular defect repairs the operation was studied experimentally in young goats. Observations were made on the appearance of the trochlea and the histologic changes that had taken place after approximately six, 12, and 40 weeks. The abraded groove became filled with fibrocartilage with a relatively smooth surface and it articulated freely with the patella. The majority of the replacement tissues arose by differentiation of the granulation tissue which initially filled the groove, but there appeared to have been some contribution made by the hyaline cartilage at the margins of the groove.     

Physeal dysplasia with slipped capital femoral epiphysis in 13 cats

Separation of the femoral capital epiphysis is associated with severe trauma in most species. This report describes 13 cats with slipped capital femoral epiphysis characterized by a distinctive lesion in the physeal cartilage. The lesion consists of irregular clusters of chondrocytes separated by abundant matrix on both the epiphyseal and metaphyseal side of the cleavage site. The affected population in this study is 85% male, 90% overweight, 23% Siamese, and 4.5-24 months old. The histopathology and demographics are similar to slipped capital femoral epiphysis in humans, which most often affects overweight adolescent boys.     

Treatment of slipped capital femoral epiphysis in cattle: 11 cases (1974-1988)

A mixed population of 11 cattle (7 dairy, 4 beef; 9 male, 2 female) were examined because of acute onset of non-weightbearing hind limb lameness. Radiography revealed slipped capital femoral epiphyseal fracture in all cattle, with the exception of one large bull. Ten of the 11 cattle were treated with open reduction and internal fixation, using intramedullary pins. Cattle affected with slipped capital femoral epiphyseal fracture in previous reports typically have been calves that required forced extraction during dystocia. Cattle in this report were in the following 2 age groups in which trauma was the likely cause: 3 to 5 months and 1.5 to 2.3 years. Follow-up information was provided for 7 of the 10 cattle. Four of the 7 were functional and had no clinical signs of arthritis, abnormal gait, atrophy, scarring, contralateral compensation, breakdown, or other difficulty 6 months after surgical correction. If early diagnosis is achieved, it appears that reduction with intramedullary pinning can provide a good long-term prognosis in cattle when function as breeding animals is important to their future value.     

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.