Trochanteric intra-osseous venography in femoral neck fractures in the dog

A study of femoral neck fracture repair using a recombinant human bone morphogenetic protein-2 directional release system

OBJECTIVE

Significant difficulties are caused by the delayed union of femoral neck fractures. To address this issue, we designed a new device that applies recombinant human bone morphogenetic protein-2 (rhBMP-2) to promote fracture union.

METHODS

A cannulated screw with holes was used to deliver rhBMP-2 to the fracture site. Fibrin glue was used as an adhesive agent to hold rhBMP-2 in the vicinity of fracture. RhBMP-2 was protected with polylactide-glycolide acid microspheres. RhBMP-2 release was evaluated to determine the effect of the improved screws.

RESULT

When polylactide-glycolide acid microspheres were used, 3.65% of the rhBMP-2 was released in the first 2 h, 5.17% was released within 8 h, and 8.95% was released within 24 h. In the microsphere + fibrin glue group, 1.15% of the rhBMP-2 was released in the first 2 h, 1.75% was released within 8 h, and 6.68% was released within 24 h. Over 42 days, about 76.75% of the rhBMP-2 was released when using fibrin glue, which was lower than the amount released using microspheres alone (91.75%). In dog, a faster repair rate was observed on the side with the improved screw than on the side with traditional screw.

CONCLUSION

The directional release system described here can improve the process of fracture healing and is a promising technique for repairing femoral neck fracture.

Can we improve fixation and outcomes in the treatment of femoral neck fractures? The use of pharmaceuticals

Femoral neck fracture rates are on the rise with an estimated 500,000 occurring annually by 2040. Despite the mainstay of open reduction and internal fixation, nonunion rates of up to 33% have been reported for displaced femoral neck fractures. Recently, increasing attention has been focused upon the role of osteobiologics to stimulate fracture repair. This article looks at the role of these anabolic compounds and discusses their potential future roles in augmenting the treatment of this condition.

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.

The healing of femoral neck fractures in dogs. The use of intraosseous venography and India ink staining

This study evaluates healing fractures of the femoral neck in dogs by using standard radiography, intraosseous venography, India ink staining and histology. The 45 animals were divided into three groups, one of which was not treated, but in the other two the fracture was fixed with a screw or two Kirschner wires. Our results suggest that, when intraosseous venography was positive India ink injection was also positive, and the late phase of fracture healing was reached.

[Phlebography of the femoral head following femoral neck fracture]

The incidence of avascular necrosis (AVN) of the head of the femur after transcervical fracture is 30-60%, depending on the diagnostic methods used. A poor outcome in AVN is not inevitable, since early diagnosis and treatment with prolonged non-weightbearing can produce satisfactory revascularisation without deformity. Nineteen patients with fractures of the femoral neck treated with internal fixation were assessed after operation by per-osseous phlebography. Weightbearing was allowed, irrespective of the state of union of the fracture, only if this test was positive. Of 13 patients who were allowed to bear weight after consolidation of the fracture, only one developed avascular necrosis. A further six patients were treated by non-weightbearing for up to eight months. Only one, in whom the fracture did not unite, developed avascular necrosis. The average time to union was 3.2 months, and the time to weightbearing was 4.1 months. This small difference, taking into account the low incidence of AVN (2 out of 19 or 10.5%, has led us to suggest a fresh approach to fractures of the femur neck in which the indications for immediate arthroplasty are restricted if the patient can tolerate prolonged non-weightbearing. Revascularisation may be assessed with phlebography and weightbearing allowed when this becomes positive. This approach should diminish the incidence of advanced AVN of the femoral head, and widen the indications for internal fixation.