Separate Centres Of Ossification Research Articles

Anatomic variations and degenerative changes in the collateral cartilages and middle and distal phalanges of the forelimb in Ardenner colts

Summary The anatomic variations and the degenerative changes in the collateral cartilages and middle and distal phalanges in 6 Ardenner colts were characterized by radiography, scintigraphy, and magnetic resonance imaging (MRI). The radiographic changes were assessed between the ages of 16.5 and 25 months. An anatomic variation of the middle and distal phalanges was demonstrated in some of the colts. MRI examination of the 6 colts revealed an association between the deep digital flexor tendon cross-sectional area and body weight as well as foot circumference. Also, a thin collateral sesamoidean (suspensory navicular) ligament was observed subjectively. The presence of an extensive ossification of the collateral cartilages of the foot was found in these young horses. The ossification was characterized by the existence of 2 separate ossification centers, which had a tendency to unite. The radiographic interphalangeal degenerative lesions seen appear as bone remodeling of the dorsal edges of the middle and distal phalanx, on the insertion sites of collateral ligaments of the distal interphalangeal joint, the digital extensor tendon, and the distal interphalangeal joint capsule.

Variation in the ossification process of the anconeal and medial coronoid processes of the canine ulna

This morphological and radiographic study investigates the ossification process of the anconeal and medial coronoid processes of the ulna in a sample of 142 dogs ranging in age from neonatal to 44 weeks. The anconeal process was noted to develop by appositional ossification, formation of a separate ossification center, or a combination of both. Several developmental stages of the ossification center of the anconeal process as well as its anatomic position and radiographic appearance are described. Differences have been noted in the shape of this ossification center as well as the ossification process itself. The medial coronoid process develops exclusively by appositional ossification. Unlike ossification of the anconeal process, ossification of the medial coronoid process was completed earlier ( P<0.05) in smaller than in the larger dogs. In smaller dogs, both the medial coronoid and anconeal processes were found to be mature by the age of 16 weeks. In the larger dogs, ossification of the anconeal process was completed not before 14 weeks of age and ossification of the medial coronoid process was completed about 6 weeks later.

Clinical significance of ossification of the cartilages of the front feet based on nuclear bone scintigraphy, radiography and lameness examinations in 21 Finnhorses.

Research on the clinical significance of ossification of the cartilages of the foot has been limited, despite the common nature of the condition and conflicting reports in previous literature. Some radiographic features in the ossification of the cartilages, such as incomplete fusion lines between separate centres of ossification and the ossified base, are of clinical significance. The relationships between radiopharmaceutical uptake in bone phase nuclear scintigraphy at the heels (palmar processes of the distal phalanx, including ossification of the cartilages of the foot), radiographic extent and type of ossification of the cartilages and clinical lameness were evaluated retrospectively in 21 Finnhorses (age > or = 4 years) in a total of 36 front feet. No significant relationship between height of the ossifications and radiopharmaceutical uptake at the ipsilateral heels existed. Clearly separate centres of ossification were not associated with increased uptake. Moderately increased uptake was suspected to be associated with ossification of the adjacent cartilage in only one foot. Intense uptake was present unilaterally in 4 horses, at one medial and 3 lateral heels. In 2 of these horses, a unilateral palmar digital nerve block relieved the mild lameness; 2 horses had no obvious lameness but had a history of being stiff or having locomotion problems during high speed trot. At 2 of the lateral heels, an incomplete fusion line was present between a large separate centre of ossification and the base, and the third horse had a high sidebone with bony protrusions, suggestive of chronic entheseopathy in a narrow foot. At the medial heel, an oblique radiograph revealed a faint radiolucent line at the base of the ossification. In all cartilages with intense radiopharmaceutical uptake at the heel and/or lameness, the ossified part of the cartilage was wider and more irregular compared to other ossifications of the front feet of the individual. Increased radiopharmaceutical uptake, associated with a different radiographic appearance from that of other ossifications of the front feet, was a conclusive sign of clinical significance. Obscure locomotion problems were more commonly associated with ossification of the cartilages than true lameness. This information is useful in lameness and prepurchase examinations and is likely also to be applicable to other coldblooded breeds used for athletic purposes.

Radial carpal bone fracture in 13 dogs

SummaryThe authors report 13 dogs with radiocarpal bone fracture. The lesion was bilateral in six cases and unilateral in seven. Clinical and radiographic examination of both the carpal joints was performed. One or two fracture lines, sagittal oblique and dorsal, of the radial carpal bone were detected. CT examination of two radial carpal bones helped in a better visualization of the fracture lines. A dorsal bone fragment of a fractured radial carpal bone was removed in one dog. Histopathology revealed the presence of fibro-connective tissue on the fracture surface of the bone fragment. The fibro-connective tissue did not seem to be the sequel to acute or chronic diseases, nor to any pathological healing process. The cancellous bone of the fragment was normal as was the bulk of the articular cartilage examined. A CT guided biopsy, including the sagittal oblique fracture surface of the radial carpal bone, was also performed. The specimens revealed the presence of immature cancellous bone with diffuse immature cartilage areas. The radial carpal bone has three separate centres of ossification: the primitive radial carpal bone, the central and intermediate carpal bone. The fusion of these centres occurs at 3-4 months of age. Histopathological findings suggest a possible “incomplete fusion” of the centres of ossification rather than a true fracture of the radial carpal bone or alternatively a “fatigue fracture”. A similar condition, involving the distal part of the humerus, was originally reported in several Cocker Spaniel dogs, and more recently in Rottweilers and Labrador Retrievers.

Estimates of heritability for ossification of the cartilages of the front feet in the Finnhorse.

Ossification of the cartilages in the foot is common in coldblooded horses, but prevalence as well as ossification pattern varies between breeds; research on estimation of heritability for the condition has been limited. Our purpose was to calculate estimates of 1) heritability for ossification parameters of the cartilages in the front feet of the Finnhorse and 2) genetic correlations between the different ossification parameters. Estimates of heritability for different ossification parameters of the cartilages in the front feet and of genetic correlations between different parameters were evaluated in data consisting of dorsopalmar radiographs of the front feet and pedigree up to the fourth generation of 964 Finnhorses (age > or = 2 years; 345 females and 619 males). Ossification at the base of the cartilages and total ossification, including separate centres of ossification, were graded 0-5 according to the most proximal point of ossification and the presence of separate centres of ossification was recorded separately. The data were analysed using a model including a fixed sex-age subclass effect and a random animal effect. Variance and covariance components were estimated with the restricted maximum likelihood (REML) method assuming an animal model. Females had more ossification than males and this difference increased with age. The ossification in the medial cartilages progressed significantly with age in females but not in males. In the lateral cartilages, the increase in ossification with age was evident in both sexes. Separate centres of ossification were an incidental finding. Estimates of heritability for the ossification parameters varied slightly between the cartilages as well as between the front feet. For total ossification, the estimates of heritability varied between 0.31 (right lateral) and 0.50 (left medial) and were slightly higher for ossification at the base of the cartilages. High genetic correlations were found for total ossification between the medial and lateral cartilages in the foot and for parallel ossification parameters between the right and left foot. The estimates of heritability were relatively high, and both cartilages and front feet have a similar genetic tendency to ossify. This information is useful in further studies assessing other factors contributing to the ossification process and also in the planning and modifying breeding programmes.

Ossification of the cartilages in the front feet of young Norwegian coldblooded horses.

The purpose of the present study was to evaluate the nature of ossification of the cartilages in the front feet of young, about 2-year-old Norwegian coldblooded horses, and to compare offspring of different sires in this respect. Dorsopalmar radiographs of the front feet of 392 horses (187 female and 205 male) were evaluated for ossification at the base of the cartilage and for separate centres of ossification. The horses were offspring of 45 different sires. Ossification extending above the navicular bone and separate centres of ossification were considered as significant. Minimal to mild ossification at the base of the cartilages was commonly seen, and significant ossification was present in one or more of the cartilages in 11.5% of the horses. The lateral compared to medial cartilages had more ossification and females had more ossification and more separate centres of ossification than males. The prevalence of horses with significant ossifications was significantly higher (46.3%) among offspring of one frequently used stallion than in the group consisting of offspring of 4 other popular stallions (3.5%) and in another group consisting of offspring of other, less frequently used stallions (9.6%). Ossification of the cartilages is considered to have a hereditary background in Norwegian coldblooded horses.

Radial carpal bone fractures in 15 dogs.

Between 1977 and 1992, 15 adult dogs were presented to the Universities of Bristol, Glasgow, Liverpool and London with fractures of the radial carpal bone which had occurred without a known episode of violent trauma. Eleven of the dogs were boxers and the other breeds affected were a Pharaoh hound, rottweiler, springer spaniel and a greyhound. The condition was bilateral in three cases. Eleven dogs were treated surgically by cast immobilisation (four cases), fragment removal (one case), lag screw fixation (three cases), pan-carpal arthrodesis (one case) and lag screw reduction followed by pan-carpal arthrodesis (two cases). The remaining four dogs were treated conservatively with rest and tactical use of non-steroidal anti-inflammatory drugs. Follow-up periods ranged from two months to 11 years. Varying degrees of lameness, which tended to be exacerbated by exercise, persisted in all cases. The radial carpal bone appears to have at least three separate centres of ossification which eventually fuse; their planes of fusion correspond approximately to the two main fracture lines. These areas of fusion could be weak points within the radial carpal bone.

RADIOGRAPHIC APPEARANCE OF THE NAVICULAR BONE AND DISTAL INTERPHALANGEAL JOINT AND THEIR RELATIONSHIP WITH OSSIFICATION OF THE COLLATERAL CARTILAGES OF THE DISTAL PHALANX IN FINNHORSE CADAVER FOREFEET

Radiographic findings in the navicular bone and distal interphalangeal joint as well as the ossification status of the collateral cartilages of the distal phalanx were evaluated in 100 Finnhorse cadaver forefeet. The most common shapes of the proximal articular margin of the navicular bone were convex and straight. Remodeling of the navicular bone was common, especially on the lateral extremity. No bony fragments were identified at the distal flexor margin even though this area appeared irregular in several feet. Several large, rounded or lollipop-shaped synovial invaginations were identified in only six feet. The thickness of the flexor cortex varied considerably, and the corticomedullary junction was uni- or bilaterally indistinct in nine feet. The shape of the sagittal ridge of the flexor cortex was commonly flat but varied. It appeared locally irregular or indistinct in 17 feet, but changes elsewhere along the flexor cortex were rare. Osteophytosis on the dorsal and palmar margins of the distal interphalangeal joint and entheseophytosis on the dorsal aspect of the middle phalanx and on the extensor process of the distal phalanx were common. "Possibly significant" ossification of the collateral cartilages (high sidebones or separate centers of ossification) was present in 36 feet; all grades of ossification in the proximal/palmaroproximal direction as well as palmar ossification were seen. A statistically significant relationship was found between entheseophytosis on the proximal flexor margin of the navicular bone and "possibly significant" ossification. Osteophytosis on the palmarodistal margin of the middle phalanx was more common in feet with a relatively long distal phalanx, suggestive of palmar ossification. Radiographic changes in the navicular bone or in the distal interphalangeal joint did not otherwise appear to be associated with ossification of the collateral cartilages of the distal phalanx in Finnhorses.

Evaluation of the variably ossified collateral cartilages of the distal phalanx and adjacent anatomic structures in the Finnhorse with computed tomography and magnetic resonance imaging.

Six Finnhorse cadaver forefeet were selected to represent radiographically different types and grades of ossification of the collateral cartilages of the distal phalanx. These cartilages and adjacent tissues were evaluated with computed tomography (CT) and high field magnetic resonance imaging (MRI). In CT the internal structure of the cartilages was consistent, but in MRI some differences were noted. The shape of the collateral cartilages and their ligamentous attachments varied. The border between ossified and non-ossified cartilage appeared distinct, with considerable variation in the extent of the ossified area in regard to the cross-sectional area of the cartilage. Ossification originating from the palmar processes and extending in the proximal/palmaroproximal direction, without separate centers of ossification, generally appeared smooth and inactive. Palmar ossification followed the irregular shape of the cartilage. Separate centers of ossification had a medullary cavity or were sclerotic. Presence of a medullary cavity or sclerosis were also found at the base of the cartilages. The incomplete fusion lines between separate centres of ossification and the ossified base of the cartilage varied from congruent and inactive to reactive with marked sclerosis, flared margins and parachondral changes. Incomplete fusion may be clinically significant. Local conformational adaptations of the hoof were also documented with extensive ossification of the collateral cartilage.

Relationship between ossification of the cartilages of the foot and conformation and radiographic measurements of the front feet in Finnhorses

One hundred Finnhorse cadaver front feet were measured and examined both radiographically and visually to report the incidence of various foot problems and their relationship to ossification of the cartilages of the foot. Ossification extending above the proximal border of the navicular bone and/or separate centres of ossification were found in 36 feet, and the lateral cartilages showed more ossification than the medial cartilages. The feet were generally broad with well developed frogs, but the long toe-low heel syndrome was a relatively common finding. Ossification of the cartilages correlated with the length of the heels but was not related to any clinically significant foot abnormalities such as contracted or under-run heels or signs of unequal weightbearing. Ossification of the cartilages did not seem to be either the cause or the result of general conformational adaptations of the front feet.

Effects of sex and age on the ossification of the collateral cartilages of the distal phalanx of the Finnhorse and the relationships between ossification and body size and type of horse

The ossification of the collateral cartilages of the distal phalanx was evaluated in dorsopalmar radiographs of the front feet of 202 Finnhorses (101 females and 101 males, aged six months to 20 years) with reference to the sex, age, body measurements and type of horse. Ossification was more common and more extensive in females than in males from about two years of age. In females, the lateral cartilages were significantly more ossified than the medial cartilages; in males, ossification was more symmetrical in the cartilages of each foot. The amount of ossification increased rapidly during the second and third years of life, and more slowly in adults. The low positive correlation coefficients between ossification and different body measurements of the horse suggested that there was more ossification in large horses, and the correlation between chest-width in adults and the extent of ossification was statistically significant. The working type of horses showed slightly more ossification than trotters and riding horses. Ossification variables, which included ossification at both the base of the cartilage and at the possible separate centres of ossification (total ossification of individual cartilages and `possibly significant' ossification in the front feet), were found to be most satisfactory for expressing the extent of ossification.

Progression and association with lameness and racing performance of radiographic changes in the proximal sesamoid bones of young Standardbred trotters

Radiographic examination of the metacarpo- and metatarsophalangeal joints was performed on 753 Standardbred trotters (6-21 months of age): 21 showed obvious changes in 26 proximal sesamoid bones on lateromedial projection. The radiographic changes were divided into 6 different types: (1) irregular abaxial margin (8 horses); (2) enlargement of the sesamoid bone (6 horses); (3) 'fracture' or separate centre of ossification of the apex (4 horses); (4) vertical, non-articular fracture of the plantar part of the sesamoid bone (1 horse); (5) a small bony fragment located in a defect in the apical part of the bone (2 horses); and (6) multiple areas of decreased radiodensity (1 horse). Each horse displayed only one type of radiographic change except for one which possessed those of types 3 and 5. Follow-up radiographic examination of 21 of the 26 affected proximal sesamoid bones at approximately 6-month intervals revealed a reduction in the changes in 13 bones and an unaltered condition in 8. Lameness examination was performed on 16 of the 21 horses at 3 years of age and 14 (87.5%) were observed to be lame, but detected lameness did not seem to be referrable to the sesamoid changes. Earnings after the racing season as 3- and 4-year-old horses showed no differences (P > 0.05) between horses with radiographic changes in the proximal sesamoid bones and those without such changes.

Radiographic evaluation of ossification of the collateral cartilages of the third phalanx in Finnhorses

Of 462 Finnhorses (age 1-20 years) evaluated and graded (scale 0-5) radiographically for ossification of the collateral cartilages of the 3rd phalanx of the front feet, 22.9% were totally free from sidebones (Grade 0), and 49.1% had minimal or mild ossification (Grade 1 or 2) at the base of 1 or more of the cartilages. Moderate ossification (Grade 3) was present in 10.2% of the horses, whereas ossification was advanced (Grade 4) or extensive (Grade 5) in 17.8%. In most horses > 1 cartilage was affected and 7.6% of the horses had separate centres of ossification in 1 or more of the cartilages. Large sidebones and separate centres of ossification were more common in females than in males (P < 0.001). The incidence of large sidebones was lower in young females (1-3 years) than in mares 4-6 years of age (P < 0.05), but did not increase significantly with age when young horses, 4-6 years of age, were compared with older ones. Grade 4 and 5 sidebones as well as separate centres of ossification were more common in the lateral than in the medial cartilage (P < 0.001), but no difference was observed in this respect between the front feet.

Post natal development of the canine elbow joint: a light and electron microscopical study

The elbows of 13 puppy cadavers were dissected, samples were taken for light and electron microscopy, and the thickness of the articular cartilage of the distal humerus and proximal ulna was measured. Throughout post natal development differences were found in the arrangement of the growth plate and articular chondrocytes. At birth, the articular surface had remnants of a fibrous limiting membrane that was continuous with the perichondrium, a finding not previously recorded in dogs. Orientation of the collagen fibrils within the matrix of the articular cartilage was initially lacking but became established by three weeks. In the humerus cartilage canals were present up to 12 weeks old. The articular cartilage of the humeral condyle varied in thickness across the joint surface, being thicker on the medial than on the lateral side; it was also thicker at the apex of the medial coronoid process. These regions of thick cartilage correspond with the sites where cartilage defects arise in elbow osteochondrosis. No histological evidence was found that the medial coronoid process of the ulna is a separate centre of ossification.

Separate centre of ossification of the lateral malleolus with instability of the ankle joint

Four cases of recurrent instability of the ankle joint are reported. The instability was associated with a separate centre of ossification of the lateral malleolus and abnormal movement between the ossicle and the distal fibula. All patients were successfully treated by surgery: two underwent internal fixation and ligamentous reconstruction and two, ligamentous reconstruction after removal of the ossicle.

Morphological variations of the ulnar styloid process

P.A. radiographs of both wrists were taken in 400 normal individuals to study the configuration of the styloid process of the ulna. Five different morphological variations were noticed, the commonest being an elongated process (102 wrists). Medially deviated (41 wrists), parrot beaked (27 wrists) and hypertrophic (16 wrists) patterns were less common. One person had bilateral unfused separate ossification centres for the ulnar styloid. There was no correlation between the length of the styloid process and ulnar variance.

Morphological Variations of the Ulnar Styloid Process

P.A. radiographs of both wrists were taken in 400 normal individuals to study the configuration of the styloid process of the ulna. Five different morphological variations were noticed, the commonest being an elongated process (102 wrists). Medially deviated (41 wrists), parrot beaked (27 wrists) and hypertrophic (16 wrists) patterns were less common. One person had bilateral unfused separate ossification centres for the ulnar styloid. There was no correlation between the length of the styloid process and ulnar variance.

ON NAVICULAR DISEASE IN THE HORSE

Osseous bodies associated with the impar ligament have been reported to be chip fractures of the distal margin of the navicular bone and a radiographic finding in navicular disease. This study demonstrates that chip fractures do exist along the distal margin of the navicular bone and that there are, in addition, three other processes by which bone tissue may develop in the impar ligament: (i) ossification secondary to ligamentous damage, (ii) separate centers of ossification within the impar ligament, and (iii) ossification of cartilage particles in adjacent synovial tissue.

Polycarpaly and other abnormalities of the wrist in chondroectodermal dysplasia: the Ellis-van Creveld syndrome.

Radiographs of 45 wrists of 23 patients who had chondroectodermal dysplasia (CED) showed variable wrist malformations, which we grouped into eight categories. In each patient, the wrists tended to be similar but seldom identical; in six patients they were sufficiently dissimilar that we classified the malformations in their two wrists into separate categories. A ninth carpal bone was present in the wrists of all patients who were five years old or older (42 of 45 wrists). It was located in the distal row, medial to the hamate bone and proximal to the fifth and sixth metacarpals. A tenth carpal bone was found in six wrists. Unlike the ninth carpal bone, it varied in location. All of the carpal bones were deformed, and two or three separate ossification centers of the hamate were found in some individuals. Fusions between the capitate, the hamate, and the ninth carpal bone were present by the last available examination in 71% of the 45 hands: these included fusions between the capitate and hamate in 7%, between the hamate and the ninth carpal bone in 47%, and between all three bones in 18%.

Instability of the ankle due to a separate centre of ossification in the lateral malleolus

A case of recurrent instability of the ankle is reported. It was associated with a separate centre of ossification in the lateral malleolus. While such extra ossification centres for both malleoli are recognized, they have not hitherto been incriminated as a cause of instability. The successful treatment of this case is described and the incidence and significance of separate ossification centres for the malleoli are discussed.