Spontaneous and bilateral necrosis of the femoral head in a young experimental beagle dog

This report describes the pathological characterizations of a rare case of necrosis of the femoral head that was spontaneous, bilateral, avascular and nontraumatic. A 14-month-old beagle dog was presented with pain in the hind limbs. At necropsy, the articular surface in the bilateral femoral head was markedly irregular. There were no gross abnormalities other than in the hip joints. Microscopically, a wide range of trabecular bone necrosis localized in the subchondral area was observed in both femoral heads. In the right femoral head, fibrosis and proliferative vessels were noted in the subchondral area. The articular cartilage was thickened irregularly, but there was no evidence of cartilage necrosis. The bone marrow adjacent to the affected area showed severe depression. In the metaphysis, atrophic bone marrow, but not bone necrosis, was observed. This was a rare case of spontaneous necrosis of the femoral head in an experimental beagle dog.     

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.     

Magnetic resonance imaging of the femoral head of normal dogs and dogs with avascular necrosis.

The purpose of this study was to describe the appearance of the femoral head of normal, young, small breed dogs, and dogs with avascular necrosis using low-field (0.3 T) magnetic resonance (MR) imaging. Images of the femoral heads were obtained in the dorsal plane, and included T1-weighted spin-echo, T2-weighted fast spin-echo, fast spin echo-inversion recovery, and fluid attenuated inversion recovery pulse sequences. MR imaging features of the asymptomatic femoral heads and necks included uniform high signal intensity compared with muscle on T1- and T2-weighted images. There was either uniform enhancement or no enhancement on postcontrast T1-weighted images. The MR imaging findings of dogs affected with avascular necrosis differed from those of asymptomatic dogs. Typically, the affected dogs had inhomogeneous intermediate to low-signal intensity within the femoral head and neck compared with muscle on T1-weighted images, inhomogeneous enhancement of the femoral head and/or neck on postcontrast T1-weighted images, and inhomogeneous low- to high- signal intensity within the femoral head and neck on T2-weighted images.     

Long term follow-up of avascular necrosis of the femoral head in the dog

In a clinical study of 35 dogs with avascular necrosis of the femoral head, 60 per cent were Yorkshire terriers; the mean age of 33 of the dogs at onset of clinical signs was seven months. The dogs had the following signs: muscle atrophy (n = 25), shortening of the affected leg (n = 14), pain on passive movement of the hip joint (n = 28), and crepitation of the hip joint (n = 8). Radiographic findings were irregular density and flattening of the femoral head in combination with degenerative joint disease. Conservative treatment consisted of exercise therapy, and surgical treatment of a standard femoral head and neck excision. In 17 of the dogs the results of therapy were evaluated with the help of a questionnaire. It is concluded that femoral head and neck excision is indicated when conservative treatment fails to lead to clinical improvement within four weeks. Femoral head and neck excision has a good long term prognosis; however, slight intermittent lameness may remain.     

Femoral Head and Neck Fractures in the Dog and Cat: A Review of 115 Cases

Case histories of 115 dogs and cats with fractures of the femoral head or neck, were reviewed; these animals had been presented to the Ohio State University Veterinary Hospital between 1969 and 1976. Signalment, fracture type by anatomic location, fracture to fixation interval, surgical approaches used, methods of surgical repair, surgical complications, and final results of surgical repair were examined. Avascular necrosis of the femoral head was not a clinically significant problem following internal fixation in this study. Most animals had very good to excellent limb function following fracture repair.     

Osteonecrosis of the femoral head of laboratory animals: the lessons learned from a comparative study of osteonecrosis in man and experimental animals

Animal models of osteonecrosis of the femoral head are indispensable to the understanding of successful treatment modalities for avascular necrosis of the femoral head in adults and in children with Legg-Calvé-Perthes disease. Many of these models adequately reflect the current "vascular deprivation" theory regarding the etiology of the disease. In addition to spontaneous occurrence, surgical- and corticosteroid-induced models are suitable, common experimental ones. Osteonecrosis of spontaneously hypertensive rats appears to be due to defective bone formation and compression of the arteries entering the femoral head at its lateral facets by daily weight-bearing loads. Successful modeling of surgical-induced femoral capital necrosis can be a challenge in animals with a dual epiphyseal blood supply. High doses of corticosteroids are a pivotal risk factor in the development of osteonecrosis. The pathogenesis of corticosteroid-induced osteonecrosis likely resides in reduced blood flow. Steroids may reduce blood flow by numerous mechanisms, including marrow adipocytic hypertrophy leading to sinusoidal compression, venous stasis and, eventually, obstruction of the arteries, and arterial occlusion by fat emboli and lipid-loaded fibrin-platelet thrombi. Other, less common varieties of osteonecrosis include those secondary to endotoxin-induced disseminated intravascular coagulation, immune reactions, immoderately low or high temperatures, and high-impact-related injuries. Common to these diverse forms of osteonecrosis are fibrin thrombi clogging arterioles and small arteries.     

Venous drainage of the femoral neck in Legg Perthes disease and in hip dysplasia. A clinical and experimental study in the dog and pig

Three clinical cases of canine avascular femoral head necrosis and 4 cases of hip dysplasia were examined using intraosseus femoral neck venography. The contrast medium passed initio the diaphyseal bone marrow in all cases. Three growing dogs and 7 growing pigs were examined with the same method, before and after experimental ligation of the femoral veins. Before the venous tamponade, no contrast medium was visible in the femoral neck. The venography performed immediately after ligation showed contrast flow into the femoral neck similar to that seen in the clinical cases of Legg Perthes disease or hip dysplasia. However, a collateral circulation developed within 7 weeks. No more contrast-flow into the diaphysis was observed after that time.Although osteomedullography shows that both in Perthes disease and in hip dysplasia venous drainage has failed, venous tamponade may not induce the onset of the disease.Key words: hip dysplasia, Legg Perthes disease, osteomedullography     

Histomorphometric analysis of the proximal portion of the femur in dogs with osteoarthritis

OBJECTIVE: To describe cancellous architecture of the proximal portion of the femur in dogs with osteoarthritis. ANIMALS: 30 dogs with coxofemoral osteoarthritis. PROCEDURE: All dogs had femoral head and neck excision or total hip arthroplasty. Histomorphometry software was used to analyze computer images of 100-microm-thick coronal and transverse plane sections of the head and neck of the femur. Histologic preparations of coronal and transverse sections of articular cartilage were graded. RESULTS: Bone volume/total volume, trabecular thickness, trabecular number, and bone surface/total volume were significantly higher in the femoral head than femoral neck. Trabecular alignment (anisotropy) and separation were significantly higher in the femoral neck than femoral head. Anisotropy was significantly increased in the medial portion of the femoral head in the coronal plane and in the cranial portion of the femoral neck in the transverse plane, compared with healthy dogs. The medial half of femoral head cartilage that overlies the proximomedial cancellous bone region had significantly more degraded cartilage than the lateral half. Histologic grades for cranial and caudal halves of femoral head articular cartilage were similar. CONCLUSIONS AND CLINICAL RELEVANCE: Most findings were similar to those in healthy dogs. Greater trabecular alignment in the proximomedial region of the femoral head and craniolateral region of the femoral neck in dogs with osteoarthritis suggests an altered transfer of load through the coxofemoral joint. Greater cartilage degradation on the medial half of the femoral head supports an association between increased trabecular alignment and cartilage degradation.     

Histomorphometric analysis of the proximal portion of the femur in healthy dogs

OBJECTIVE: To describe the cancellous bone architecture of the head and neck of the femur in healthy dogs by use of automated histomorphometry techniques in conjunction with histologic grading of articular cartilage. ANIMALS: 30 mature male dogs with healthy coxo-femoral joints PROCEDURE: Dogs were 1.5 to 4 years old and weighed 27 to 37 kg. Computer images of fine-detail radiographs of 100-microm-thick coronal and transverse plane sections of the head and neck of the femur (14 dogs) were analyzed by use of histomorphometry software. Statistical comparisons among histomorphometric indices of 4 regions were performed. Histologic preparations of coronal and transverse plane sections of femoral head articular cartilage (16 dogs) were graded. Median grades for lateral, medial, cranial, and caudal halves of the femoral head articular cartilage were determined. RESULTS: Bone volume/total volume, trabecular thickness and number, and bone surface/total volume were significantly higher in the femoral head than in the femoral neck. Anisotropy (trabecular alignment) and trabecular separation were significantly higher in the femoral neck than in the femoral head. Anisotropy was significantly higher in the caudal half of the femoral neck than in the cranial half. Cartilage had histologic grades indicating health without significant differences among lateral, medial, cranial, and caudal halves of femoral head cartilage. CONCLUSIONS AND CLINICAL RELEVANCE: A predictable cancellous architecture in the head and neck of the femur is associated with healthy cartilage.     

ESTIMATION OF SOFT TISSUE INTERPOSITION AFTER FEMORAL HEAD AND NECK EXCISION IN DOGS USING VENTRODORSAL PELVIC RADIOGRAPHY

Extended-hip ventrodorsal pelvic radiographs performed on 16 dogs after femoral head and neck excision, with (n = S) and without (n = 8) biceps femoris interpositional muscle flaps, were used to estimate the relative amount of soft tissue interposition between the femoral ostectomy site and acetabulum. A linear measurement was made of the shortest distance between the femoral ostectomy and the acetabulum. The linear measurement was capable of determining the presence of biceps femoris muscle flaps in most dogs prior to flap atrophy or necrosis, but failed to be predictive of limb function as determined by functional limb usage grading, force plate analysis, and thigh circumference measurements.     

Observations on femoral head abnormalities in broilers

Detachment of the proximal femoral cartilaginous epiphysis was observed in broilers that were being down-graded at slaughter as a result of haemorrhage into thigh musculature. A traumatic aetiology is proposed with injury occurring at catching. Examination of field case material, and birds culled from a commercial flock of the same strain, revealed that physeal lesions are not infrequent in proximal femora. Clefts and areas of matrix necrosis occurred in normal and dyschondroplastic physeal cartilage. Clefts were thought to result from repetitive minor trauma insufficient to cause total detachment of the cartilaginous epiphysis. Total detachment may result from an acute traumatic episode or be a consequence of pre-existing physeal lesions. A traumatic aetiology suggests that in such cases the terms fracture separation or traumatic epiphyseolysis of the cartilaginous epiphysis are more appropriate than femoral head necrosis or degeneration.     

Histomorphometric analysis of the proximal portion of the femur in dogs with moderate osteoarthritis

OBJECTIVE: To describe the histomorphometric properties of epiphyseal and metaphyseal trabecular bone of the proximal portion of the femur of dogs with moderate osteoarthritis. SAMPLE POPULATION: Proximal portions of a femour from 24 dogs. PROCEDURE: The proximal portion of a femur was obtained from each dog. Eleven and thirteen specimens were sectioned in the transverse and coronal planes, respectively. Three evenly spaced sections from each specimen were chosen, surface stained, and digitized, and the stained areas were preferentially selected. Custom software was used for histomorphometric analysis of each section. A mixed-model analysis was used to evaluate the effect of slice location and region on 6 parameters, and a Fisher protected t test was used when differences were detected. RESULTS: There was a significant difference between the femoral head and femoral neck for all parameters tested. In coronal sections, the femoral neck was significantly more anisotropic than the femoral head. In transverse sections, the craniolateral region of the femoral neck was significantly more anisotropic than the caudomedial and craniomedial regions. CONCLUSIONS AND CLINICAL RELEVANCE: There is a predictable cancellous microarchitecture in the proximal portion of femurs from dogs with moderate osteoarthritis. Trabeculae are more numerous, thicker, and closer together but more randomly arranged in the femoral head than in the femoral neck. Dogs with moderate osteoarthritis had an increase in trabecular anisotropy in the craniolateral region of the femoral neck. However, there was no corresponding increase in trabecular alignment of the proximomedial region of the femoral head. Results support an association between trabecular alignment and the progression of osteoarthritis.     

Effect of triple pelvic osteotomy on the proximal femoral geometry in dysplastic dogs

Triple pelvic osteotomy (TPO) is one of the surgical procedures for use to try to reduce subsequent degenerative joint disease or modify the progress of hip dysplasia in young dogs. Joint force and pressure distribution were changed by this procedure. Therefore, the aim of this study was to find out whether the remodeling of proximal femur exists or not after TPO in dysplastic dogs. Ten femora from five young dysplastic mongrel dogs, treated unilaterally with TPO using 20° canine pelvic osteotomy plates, were used. One year after TPO, neck-proximal shaft angle, femoral head, neck, diaphyseal and mid-shaft diameters, total femoral, femoral neck axis, and intertrochanteric, femoral head offset lengths as well as the lengths from head center to lateral margin of greater trochanter and to proximal femoral axis were measured from the bone. The significant differences between treatment and control side were determined in Norberg angle, neck-proximal shaft angle, neck diameter, diaphyseal diameter, mid-shaft diameter, length from head center to proximal femoral axis and femoral head offset length. In conclusion, although small number of cases was used, it was determined that the aforementioned variables are affected by TPO. So, these variables may be supply additional information about the changes to the joint following TPO in dysplastic dogs.     

Orthotopic Osteochondral Transplantation of the Canine Proximal Femur

An 18-week study was conducted to evaluate orthotopic osteochondral transplantation of the proximal femur in the dog. Eighteen dogs were divided into 3 groups of 6 each. The first group received autografts, the second received fresh allografts, and the third received grafts that had been frozen in a bone bank for 24–28 days. The grafts were fixed in position using dynamic compression plates. The grafted limbs were maintained in a sling and thus were nonfunctional and non-weight bearing throughout the 18-week study. Postoperatively the dogs were given oral tetracycline to assess osteo- cyte viability. The dogs were radiographed at 2–week intervals and 1 dog in each group was euthanatized every 3 weeks. The femurs were examined using standard histopathologic and fluorescent labeling techniques. All femoral heads were luxated by the 2nd postoperative week. The bones of all the femoral heads underwent avascular necrosis and degenerative changes were present in the transplanted cartilage by the 6th postoperative week. During the first 18 weeks following transplantation there was little radiographic and histologic difference among the 3 types of grafts regarding the nature and rate of bone healing. Based on the data obtained from techniques utilized in this study, the femoral head, neck, and articular cartilage did not survive, while the femoral diaphysis did survive the transplantation process. Different techniques may alter to some degree the results obtained.     

A Comparison of Standard Femoral Head and Neck Excision and Femoral Head and Neck Excision Using a Biceps Femoris Muscle Flap in the Dog

Sixteen normal 20 to 30 kg dogs had standard femoral head and neck excision (8 dogs) or femoral head and neck excision with interposition of a biceps muscle flap (8 dogs). Lameness lessened at week 6, and did not differ between groups; neither group returned to a completely normal gait. Weightbearing decreased on the operated pelvic limb compared to controls (forceplate analysis). Weightbearing force of the muscle flap dogs was significantly less at weeks 6 and 16 than that of the standard femoral head and neck excision dogs. The operated limb of both groups was shortened; shortening was significantly greater for the muscle flap group. Hip extension was limited in both groups. Both groups had decreased (more acute) hip, stifle, and hock angles measured in standing position. Thigh muscle atrophy was more pronounced in the muscle flap group at week 6. More soft tissue was interposed in the muscle flap group at necropsy compared to the group with standard femoral head and neck excision, but the difference was not statistically significant. Skeletal muscle fibers were present in the interposed fibrous connective tissue of the muscle flap group, and the healed surfaces were smoother than those of the standard femoral head and neck excision group.     

Influence of femoral head and neck conformation on hip dysplasia in the German Shepherd dog.

We investigated the prevalence of an anatomic variant of the proximal femur, termed the broomstick-like femoral head and neck formation, and its influence on the Féderation Cynologique Internationale (FCI) hip dysplasia score in 294 German Shepherd dogs. One-hundred and eighty (61%) of the 294 dogs in our study had this anatomic variant. The calculated area of the femoral heads in dogs with a broomstick-like conformation was 4.5 +/- 0.6 cm2 on the hip-extended view. In dogs with a normal femoral head, the calculated area of the femoral head was significantly larger at 4.8 +/- 0.6 cm2 (P < 0.05). In the frog-leg view, there was no significant difference in femoral head area between dogs with the broomstick-like conformation and normal dogs. There was no difference in the antetorsion angle between dogs with broomstick-like conformation and normal dogs. There was also no difference in the distraction ratio between the two phenotypes. The official FCI hip score was similar in dogs with and without the broomstick-like conformation. The average heritability of the broomstick-like conformation was 0.3 +/- 0.1, suggesting heritable influence. We conclude that the broomstick-like conformation is a common finding in the German shepherd dog and has genetic base. The broomstick-like conformation does not appear to be associated with the presence of canine hip dysplasia and it can therefore be assumed to be a normal anatomic variant.     

Subchondral cystic lesions (osteochondrosis) of the femoral heads in a horse

Bilateral subchondral cystic lesions of the femoral head in a horse resulted in lameness. The lesions had resulted in degenerative disease in the left coxofemoral joint. The cause of lameness was confirmed by use of intra-articular anesthesia, joint fluid analysis, and radiography. Subchondral cystic lesions involving the femoral head should be considered in the differential diagnosis of equine lameness localized in the upper portion of the hind limb.     

Internal fixation of femoral head and neck fractures in the cat

A quick surgical approach for internal reduction and fixation of femoral head and neck fractures is described. The results and reasons for preferring this technique to femoral head and neck excision are discussed.