Changes in intraosseous pressure and medullary blood rheology following drilling decompression in rabbits with intraosseous hypertension

Yujin TANG; Minan LU; Shengcai PAN

ABSTRACT

BACKGROUND:

In clinic, many orthopaedic diseases are related to abnormal increase of intraosseous pressure, such as, avascular necrosis of femoral head and osteoarthritis and so on. Percutaneous bone puncture and other methods can decrease intraosseous pressure and release clinical symptoms immediately. Analysis on the changes in intraosseous pressure and medullary blood rheology following drilling decompression can further recognize the occurrence and development of intraosseous pressure

OBJECTIVE:

To observe the changes in intraosseous pressure and medullary blood rheology following drilling decompression in rabbits.

DESIGN:

A randomized and controlled trial.

SETTING:

Department of Orthopaedics, Affiliated Hospital of Youjing Medical College for Nationalities.MATERIALS This experiment was carried out at Orthopaedic Department, Affiliated Hospital of Youjing Medical College for Nationalities between March and December 2005. Totally 30 New Zealand purebred white rabbits, of either gender, weighing (2.16±0.35) kg, were provided by Experimental Animals Center of Guangxi Medical University.

METHODS:

① Animals grouping and modeling 30 rabbits were randomly divided into 2 groups model group and experiment group with 15 in each group. Intraosseous pressure models of the proximal right tibia were created on the rabbits in the two groups and drilling decompression was performed in the proximal tibia of rabbits in the experiment group. ②Measurement of intraosseous pressure of proximal tibia After rabbits were anesthetized, needle for measuring blood pressure was pricked into the medullary canal at 0.5 cm internal plane up at the tubercle of right tibia.Intraosseous pressure of two groups was measured before and 2 days after decompression with BL-410 biologic functional system. ③ Measurement of medullary blood rheology Before and 2 days after drilling decompression,medullary blood was extracted and blood rheology was measured with Blood Perfusion Monitor R80 (Vertebral plate type, Version 5.0) in the experiment group.MAIN OUTCOME

MEASURES:

Value of intraosseous pressure and medullary blood rheology before and after drilling decompression in the proximal right tibia.

RESULTS:

All the 30 rabbits entered the stage of result analysis. ①Measurement of intraosseous pressure intraosseous pressure was significantly lower after drilling decompression in the proximal right tibia in the experiment group than in the model group (P ＜ 0.01). It approached normal value of intraosseous pressure of control side [(2.50±0.39) kPa]. Intraosseous pressure in the experiment group was significantly lower after than before drilling decompression (P ＜ 0.01). ② Measurement of medullary blood rheology Medullary blood viscosity, plasm viscisity, whole blood reduced low-shear viscosity, red cell rigidity index, whole blood high-shear relative viscosity, whole blood low-shear relative viscosity, erythrocyte deformation index and erythrocyte aggregation index at the proximal end of tibia following drilling decompression were significantly lower than those before drilling decompression (P ＜ 0.05 or 0.01). Medullary erythrocyte sediment rate and erythrocyte hematocrit did not change significantly (P ＞ 0.05).

CONCLUSION:

Drilling decompression in proximal right tibia can obviously decrease intraosseous pressure, dilute medullary blood and decrease blood viscosity.