Fabiano Ribeiro MS, Fernando Tavares MS, Antonio Tenor, Jaques Waisberg MD
apresentação no Congresso da Academia Americana de Ortopedia - LAS VEGAS - 2009
INTRODUCTION
The process of fracture repair involves both local and systemic factors. Systemic osteogenic response has been observed to stimulations distant from the fracture site, such as lesions to bone marrow and/or blood loss. The objective of the present study was to assess the influence of systemic osteogenic response caused by distant stimulation of bone marrow, in consolidation of a bone gap.
METHOD
A total of 36 young adult male New Zealand White rabbits were employed, having a mean weight of 2.9kg (2.5 to 3.3kg). The animals were randomly assigned into three groups (A, B and C) containing twelve animals each. Venous drain was performed on the member using an elastic bandage and tourniquet at the base of the foreleg. Group A animals, while still under the original anesthetic, were subjected to bone marrow stimulation by partial ablation of the left femur through aspiration of 3ml of content from the medulla canal using a 20ml syringe and biopsy puncture needle. The material collected from the femoral medullary canal was discarded. In Group B, while still under the original anesthetic, bone marrow was stimulated by introducing a 1.5mm-thick Kirschner wire into the left femoral medulla canal. Group C, which constituted the control group, underwent no distant stimulation of bone marrow. All of the rabbits were sacrificed at the end of the fourth post-operative week. The lower forelegs of the animals were then dissected, and radii resected together with the ulna.
Histomorphometric Study
For each animal, the areas of cartilaginous, osseous and fibrous tissue were summed to yield total bony callus area. The proportional area of each tissue type was obtained by calculating the ratio between the area of tissue in question, divided by the bony callus area.
Radiographic Study
Weekly radiographs were analyzed according to the Lane and Sandhu radiographic scoring system and assessed for bone consolidation evolution at the ostectomy site by an orthopedist blinded to the study data.
RESULTS
At study end-point, the groups with distant bone marrow stimulation had a lesser number of bone cells compared to the control group. On radiographic studies, no difference in evolution of consolidation was evident between the groups.
DISCUSSION
An increasing number of studies on bone consolidation and influence of growth factors have been conducted in a bid to accelerate recovery of patients with fractures. Authors have carried out experiments in an attempt to identify substances produced by the organism which are linked to bone formation.
The difference between the present results and those of the literature may be explained by the following arguments: a) the scarcity of studies involving this type of experiment; b) the low number of experiments conducted in rabbits; c) the use of diverse methodological criteria by previous studies; d) reduced bleeding during the surgical procedure by tourniquet use.
CONCLUSION
Under the conditions of the present experiment and in the light of results obtained, it was concluded that distant bone marrow stimulation, associated with reduced intra-operative bleeding, negatively influenced bone gap consolidation in rabbits.
