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.     

Evaluation of the proximal portion of the femur as an autogenous cancellous bone donor site in dogs.

The proximal portion of the femur was evaluated as a source of autogenous cancellous bone in dogs. Bilateral oval cortical defects were created in the lateral subtrochanteric area of the femur in 16 dogs. Cancellous bone was removed and the weight recorded. Cancellous bone was similarly harvested from the proximal portion of the humerus in 7 of these dogs. Subtrochanteric femoral defects in 11 dogs were randomly assigned to receive cancellous bone graft obtained from the femur (n = 4) or the humerus (n = 7). Subtrochanteric defects in 5 dogs were not grafted. Radiographic assessment of subtrochanteric defects was performed at 4-week intervals, and histologic assessment at 4, 8, 16, and 24 weeks after surgery. Nongrafted donor sites healed by ingrowth of trabecular bone during the first 12 weeks after surgery. By week 24, the lateral cortical wall had reformed, but remodeling was incomplete. Donor sites grafted with cancellous bone healed similarly, but with more rapid healing and more complete remodeling evident by week 24. Although the mean weight of cancellous bone harvested from the proximal portion of the femur (0.82 +/- 0.22 g) was significantly (P less than 0.05) less than that harvested from the proximal portion of the humerus (1.38 +/- 0.29 g), there was no qualitative histologic or radiographic difference in bony healing of grafted defects. We determined that the proximal portion of the femur can be safely used to provide moderate amounts of cancellous bone, and that a second bone graft can be collected from the same subtrochanteric donor site after 12 weeks.     

Histomorphometric analysis of articular cartilage, zone of calcified cartilage, and subchondral bone plate in femoral heads from clinically normal dogs and dogs with moderate or severe osteoarthritis

OBJECTIVE: To quantify and compare the microscopic changes in articular cartilage (AC), zone of calcified cartilage (ZCC), and subchondral bone plate in femoral heads from clinically normal dogs and dogs with moderate or severe osteoarthritis. SAMPLE POPULATION: Femoral heads from clinically normal dogs (n = 16) and dogs with moderate (24) or severe (14) osteoarthritis. PROCEDURES: Femoral heads were allocated to 3 categories (normal, moderate, or severe osteoarthritis) on the basis of radiographic findings, macroscopic findings, and histologic grade determined by use of a modified Mankin scale. Equally spaced 2-mm sections were cut in each femoral head in a coronal or transverse plane. Thickness of the AC, ZCC, and subchondral bone plate was recorded. RESULTS: Mean thickness of AC was significantly greater in samples with moderate and severe osteoarthritis than those considered normal. Mean thickness of the ZCC was significantly greater in samples with moderate and severe osteoarthritis than those considered normal. Mean thickness of the subchondral bone plate in samples with severe osteoarthritis was significantly greater than those with moderate osteoarthritis and those considered normal. A significant decrease in AC thickness was detected in the proximomedial area of femoral heads with severe osteoarthritis, compared with those considered normal. CONCLUSIONS AND CLINICAL RELEVANCE: A cause and effect association between thickening of subchondral structures and thinning and loss of the overlying AC was not detected. Changes in AC were associated with changes in the subchondral bone plate, which is compatible with the theory of adaptation in response to altered load distribution.     

Alterations in bone remodeling in the femur after medullary reaming and cemented hip arthroplasty in dogs.

OBJECTIVE: To determine whether medullary reaming alone, or followed by cemented hemiarthroplasty, influenced porosity, vascularity, and new bone formation in the proximal portion of the femur in dogs. ANIMALS: 12 adult mixed-breed dogs. PROCEDURE: Unilateral femoral head and neck excisions were performed, followed by femoral medullary reaming in 6 dogs and femoral medullary reaming and cemented hemiarthroplasty in 6 dogs; the contralateral femur was used as a control. All dogs were euthanatized 28 days after surgery, and femurs were harvested. Vascularity, porosity, and new bone formation were quantified for all femurs of dogs from both groups at 3 proximal-to-distal levels, 3 regions (periosteal, midcortical, and endosteal), and 4 quadrants (cranial, caudal, medial, and lateral) of the femur. RESULTS: Medullary reamed and cemented hemiarthroplasty femurs had significant increases in vascularity and porosity at all levels and in new bone formation at levels 2 and 3. Porosity was increased significantly in the periosteal region of the cemented hemiarthroplasty (9.7+/-0.7%), compared with control (2.3+/-0.2%) and medullary reamed (8.4+/-0.7%) femurs. Porosity was increased in the caudal and medial quadrants in the medullary reamed and cemented hemiarthroplasty femurs; vascularity results were similar. CONCLUSION: Increased porosity, vascularity, and new bone formation in reamed and cemented hemiarthroplasty-treated femurs supports the theory that surgical trauma associated with medullary reaming is an important factor in early cortical bone loss after hip arthroplasty. CLINICAL RELEVANCE: Femoral remodeling associated with reaming and broaching is appreciable but may be only a temporary response, whereas other factors may be responsible for chronic cortical bone loss.     

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.     

Vascular and Morphologic Changes in Canine Femora after Uncemented Hip Arthroplasty

The effects on femoral remodeling of medullary reaming and insertion of a porous endopros-thesis in uncemented hip arthroplasty (UHA) were measured. A unilateral hip hemiarthroplasty (HA) was performed in 12 dogs, with six dogs receiving full-sized and six dogs receiving undersized femoral endoprostheses. A prosthetic head and neck, or acetabular cup, was not implanted. A control group of six dogs underwent femoral head and neck excision (FHNE) only. All dogs were killed 4 weeks after the surgical procedure. Porosity, vascularity, and bone formation were quantified in each femur of the dogs that had been operated on and in each femur of two unoperated dogs. Full-sized did not differ from undersized HA bones in vascularity, porosity, or bone formation. Femurs in which hemiarthroplasties had been performed (full-sized and undersized) had a three-fold increase in porosity, vascularity, and bone formation compared to the contralateral and the FHNE femurs. Changes in porosity and vascularity were greatest (p < .05) at the metaphyseal level and in the medial and caudal quadrants. There was a strong correlation (R² 0.77 to 0.93, and p − .0001) between the increase in porosity and vascularity. These results support the hypothesis that medullary reaming followed by uncemented prosthetic stem implantation contribute to remodeling of the proximal portion of the femur after UHA.     

Assessment of bone mineral density of the femoral head in dogs with early osteoarthritis

OBJECTIVE: To compare the bone mineral density (BMD) of the proximal portion of the femur in dogs with and without early osteoarthritis secondary to hip dysplasia. ANIMALS: 24 dogs (3 Greyhounds, 6 Labrador-Greyhound crossbreeds, and 15 Labrador Retrievers). PROCEDURE: Computed tomography (CT) of the pelvis, including a bone-density phantom, was performed for each dog. Centrally located transverse CT slices and a computer workstation were used to identify 16 regions of interest (ROIs) in the proximal portion of the femur. For each ROI, the mean Hounsfield unit value was recorded; by use of the bone-density phantom and linear regression analysis, those values were converted to equivalent BMD (eBMD). Mean eBMD values for the subchondral and nonsubchondral ROIs in dogs with and without osteoarthritis (determined at necropsy) were compared. A mixed-model ANOVA and post hoc linear contrasts were used to evaluate the effects of osteoarthritis, breed, and sex on the BMD value. RESULTS: At necropsy, osteoarthritis was detected in 14 hip joints in 9 dogs; all lesions included early cartilage fibrillation. After adjusting for breed and sex, eBMD in subchondral ROIs 8 and 12 (adjacent to the fovea) were 8% and 6% higher, respectively, in osteoarthritis-affected dogs, compared with unaffected dogs; in the nonsubchondral ROIs, eBMD was 10% higher in osteoarthritis-affected dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with findings in unaffected dogs, increased eBMD in hip joints of dogs with early osteoarthritis supports a strong relationship between the subchondral and epiphyseal regions and articular cartilage in the pathogenesis and progression of osteoarthritis.     

Changes in the Proximal Femur and Coxofemoral Joint Following Intramedullary Pinning of Diaphyseal Fractures in Young Dogs

We report radiographic changes and clinical results seen in the proximal femur and coxofemoral joint of 7 young dogs following intramedullary pinning. Changes seen radiographically included coxa valga, a small malformed femoral head, a short thin femoral neck, and coxofemoral subluxation. Epiphyseal trauma, ischemia, and mechanical impairment of normal femoral neck growth due to presence of the intramedullary pin are discussed as possible etiologic factors.     

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.     

COMPARATIVE STRUCTURAL ANALYSIS OF THE CANINE FEMORAL HEAD IN LEGG-CALVÉ-PERTHES DISEASE

The goal of this study was to examine the microarchitecture of the trabecular bone of the canine femoral head using microcomputed tomography (micro-CT) technology. Specifically, we assessed changes seen in the femoral head in dogs with Legg-Calvé-Perthes disease and compared this with changes seen in dogs with hip dysplasia and coxofemoral luxation. Femoral heads from healthy animals were examined as a control. In total, 38 femoral heads were studied. Rules for defining spherical volumes (region of interest) for determination of the structural parameters within the trabecular structure were established using micro-CT images. The following parameters were determined directly in three dimensions: bone volume fraction, surface volume fraction, trabecula thickness, trabecular count, trabecular spacing, and connectivity. Characteristic femoral head changes were found for each condition. An unexpected result was found that contradicts the prevailing understanding of Legg-Calvé-Perthes disease. Instead of observing a thickening of the bone trabeculae caused by layering of new bone matrix on top of necrotic trabeculae, we observed an increase in trabecular count and a smaller trabecular thickness. From this it may be concluded that trabecular regeneration is more prominent or prevails over the characteristically described layering processes in the revascularization and repair processes occurring in this illness.     

Coxofemoral arthroscopy and total hip arthroplasty for management of intermediate grade fibrosarcoma in a dog

OBJECTIVE: To report the use of arthroscopy and total hip arthroplasty (THA) for management of intermediate grade fibrosarcoma of the femoral head in a dog. STUDY DESIGN: Clinical case report. ANIMAL: A 6-year-old spayed female Rottweiler presented for evaluation of acute-onset of lameness of the right pelvic limb of approximately 10 days duration. METHODS: Coxofemoral arthroscopy was performed to obtain fine needle aspiration and Jamshidi biopsy of a lytic lesion of the femoral head. A cemented THA was performed removing as much of the femoral neck and proximal femur as possible while not compromising implant or joint stability. RESULTS: Histologic evaluation of specimens from the femoral head and neck remnants confirmed an intermediate grade fibrosarcoma. Fifteen months after THA, subjectively there was normal use of the right limb with only limited decrease in range of motion and mild muscular atrophy. Radiographs demonstrated stationary positioning of the THA implants. CONCLUSIONS: Arthroscopy of the coxofemoral joint is an effective diagnostic tool for evaluation of disease of the articular structures and canine total hip replacement may be an appropriate means of limb salvage in rare cases of disease of the femoral head. CLINICAL RELEVANCE: This case provides support for the use of coxofemoral arthroscopy as a diagnostic tool as well as an aid in acquiring representative intraarticular tissue samples. Additionally, the case presented demonstrates the potential use of THA as a limb sparing technique in cases of disease affecting the femoral head of dogs.     

1例猫股骨头颈部骨折的诊断和治疗

犬猫单纯的股骨头颈部骨折临床上较少,其发病原因是骨盆或股骨受到直接或间接的外力导致,也常继发于髋关节发育不良导致的骨质疏松,轻微的外力就可造成动物的股骨头颈部骨折。介绍了猫股骨头颈部骨折的临床症状、诊断及治疗过程,以供参考。     

Proximodistal alignment of the canine patella: radiographic evaluation and association with medial and lateral patellar luxation

Objectives— To evaluate the contribution of proximodistal alignment of the patella to patellar luxation, and to evaluate the structures contributing to proximodistal alignment of the patella relative to the femoral trochlea.
Study Design— Retrospective study using a convenience sample.
Animals— Medium to giant breed dogs (n=106).
Methods— Medical records and stifle radiographs of 106 dogs were reviewed. Radiographic measurements evaluated the proximodistal alignment of the patella with respect to the femoral trochlea, distal aspect of the femur, and proximal aspect of the tibia. Measurements were compared between dogs with clinically normal stifles (controls; n=51 dogs, 66 stifles), and dogs with a clinical diagnosis of medial patellar luxation (MPL, n=46 dogs, 65 stifles) or lateral patellar luxation (LPL, n=9 dogs, 11 stifles) using ANOVA.
Results— In dogs with MPL, the ratio of patellar ligament length (PLL) to patellar length (PL) was increased, as was the ratio of the distance from the proximal aspect of the patella to the femoral condyle (A) to PL ( P <.0001). Dogs with LPL had a decreased A:PL ( P =.003) and an increased ratio of the proximal tibial length (PTL) to distal tibial width (DTW; P =.009).
Conclusions— MPL is associated with a relatively long patellar ligament and patella alta in medium to giant breed dogs. LPL is associated with a relatively long proximal tibia and patella baja. Values for PLL:PL>2.06 and A:PL>2.03 are suggestive of the presence of patella alta, whereas a value for A:PL<1.92 is suggestive of patella baja.
Clinical Relevance— Measurements of both PLL:PL and A:PL are recommended in dogs with patellar luxation, and surgical correction should be considered in those with abnormal values.     

Dual-energy X-ray absorptiometry in canine legg-Calvé-Perthes disease

Radiographic examination and subsequent dual-energy X-ray absorptiometry scans of the hips were performed in seven dogs with monolateral Legg-Perthes-Calvé disease to quantify bone changes produced by osteonecrosis in the proximal femur on the affected and unaffected side. All dogs were found to be affected with grade 2 and 3 of the radiographic classification proposed by Ljunggren. Bone mineral density (g/cm(2)) of the femoral neck and proximal femoral metaphysis were evaluated on the affected and unaffected side; we detected no differences in bone mineral density for both regions of interest within the population studied in relation to gender, body weight and side analysed nor between the affected and the unaffected limb. We therefore assume that radiographic areas of decreased density in the proximal femoral epiphysis during chronic stages of Legg-Calvé-Perthes disease do not alter the global mineral content of the scanned region.     

Removal of infected canine cemented total hip prostheses using a femoral window technique

OBJECTIVE: To evaluate a femoral window technique for retrieval of cemented total hip prostheses. STUDY DESIGN: Retrospective clinical study. ANIMALS: Twelve dogs with infection of a cemented modular total hip prosthesis. METHODS: Implant removal was performed by an extended craniolateral approach to the hip and proximal femur without trochanteric osteotomy. The femoral cement mantle was fragmented and removed with simple orthopedic instrumentation by a lateral femoral window that was repaired using cerclage wires. Surgical technique, intraoperative and postoperative complications, bacterial culture results, histopathologic findings, and completeness of cement removal were recorded. Follow-up radiographs were taken 5 to 9 weeks postoperatively. Long-term follow-up information was obtained by client questionnaire. Functional outcome was assessed by scoring ability to stand, sit, walk, run, play, climb stairs, and get into a car. RESULTS: Prosthesis retrieval was performed 2 to 41 months after implantation (median, 14 months). Complete removal of femoral cement was achieved in 10 dogs. A nondisplaced femoral fissure, extending proximally from the window, was an intraoperative complication in 2 dogs. Staphylococcus spp was most commonly isolated (6 dogs) from interfacial membrane samples. Systemic antibiotic therapy, dependent on susceptibility testing, was administered for 3 to 10 weeks postoperatively. There was radiographic evidence of osteotomy healing at 5- to 9-week reassessment. Recurrence of osteomyelitis was not observed. Long-term functional outcome was considered mildly abnormal. CONCLUSIONS: The lateral window was an effective technique for retrieval of retained femoral cement. CLINICAL RELEVANCE: Removal of an infected prosthesis using this technique generally resulted in a clinical outcome comparable to that with ab initio femoral head and neck excision.     

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.     

Complications of transposition of the fibular head for stabilization of the cranial cruciate-deficient stifle in dogs: 80 cases (1982-1986)

Over a 5-year period, fibular head transposition was performed in 85 stifles in 80 dogs with rupture of a cranial cruciate ligament. The most common complication during surgery was iatrogenic fracture of the fibular head or neck (10 dogs; 12.5%), and the most common postoperative complication was seroma formation at the lateral aspect of the proximal portion of the tibia overlying the pin (6 dogs; 7.5%). Sixty-nine of 80 owners were contacted for follow-up evaluation of lameness 6 months to 5 years after surgery; 51% reported excellent results, 39% good results, and 10% fair results. Fifty-six dogs were available for long-term follow-up examination; all dogs had some degree of medical thickening of the stifle, 27 (48%) had crepitus, 4 (7%) had signs of pain, and 2 (3.5%) had moderate cranial drawer instability on manipulation of the joint. Results were good or excellent in 90% of the dogs.     

Cutaneous hybrid cyst in four dogs

Cutaneous hybrid cysts were recognized in 4 dogs. The lesions were solitary, asymptomatic, and occurred over the head, neck, proximal thigh, and lumbar region. These cysts were not accompanied by other disease processes, and did not recur following surgical excision. Histologically, the hybrid cyst is characterized by epidermal differentiation in its upper portion, and trichilemmal differentiation in its lower portion.