Annals of Clinical & Laboratory Science 35:449-452 (2005)
© 2005 Association of Clinical Scientists
Effect of Femoral Nutrient Artery Ligature on Radionuclide Uptake in Rabbits
Xiaofeng Zeng,
Weiju Lu,
Jianning Zhao,
Ting Guo and
Bin Li
Department of Orthopaedics, Jinling Hospital, Nanjing University Medical School, Nanjing, PR China
Address correspondence to Xiaofeng Zeng, M.D., Department of Orthopaedics, Jinling Hospital, 305 East Zhongshan Rd., Nanjing 210002, People’s Republic of China; tel 86 25 8481 7280; fax 86 25 8454 7309; e-mail: zengxiaofeng{at}msn.com.
 |
Abstract
|
|---|
To elucidate the effect of damaging the nutrient artery to a long bone, we used radionuclide imaging to survey the change of femoral blood supply after ligating the nutrient artery in rabbits. The radionuclide uptake of the femoral shaft, upper and lower metaphysis, and epiphysis decreased significantly at 1 hr postoperation (0.66, 0.74, 0.81, respectively, p <0.05), were close to normal on day 4 (0.96, 0.98, 1.02, respectively, p >0.05), slightly exceeded the contralateral level at 9 and 12 days, and returned to normal on day 16. This study shows that ligation of the nutrient artery of a long bone leads to an immediate decrease in the bone blood flow. However, so long as anastomoses among other bone vessels are intact, the recovery rate is speedy, and long-term, serious disorders of the bone blood supply do not ensue.
Keywords: nutrient artery, femoral blood supply, radionuclide imaging, long bone vasculature
|
Introduction
|
|---|
The nutrient artery is an important source of blood to long bone, nourishing most of the diaphyseal cortex of a long bone and anastomosing with the metaphyseal arteries at each end of the medullary cavity [1–5]. The nutrient artery may be damaged during surgical operations or trauma. The effect of nutrient artery impairment on long-bone blood supply remains poorly understood. Therefore, the present work was undertaken to explore the changes in long-bone blood supply using a radionuclide imaging technique after ligation of the femoral nutrient artery in rabbits.
|
Materials and Methods
|
|---|
Animals and surgical techniques.
Japanese white rabbits (age, 8–10 mo, n = 12), weighing an average of 1.88 kg (range, 1.72 to 2.24 kg), were randomly divided into 2 groups: controls (6 rabbits) and ligation-treated (6 rabbits). Maturity was confirmed by radiographic demonstration of closure of the distal femoral epiphysis. Institutional Review Board Approval was obtained before the study was undertaken.
In a preliminary study using angiography and anatomic dissection, we found that there is only one nutrient artery in the femur of rabbits, and its entry is situated about one cm below the trochanter minor. The 6 rabbits in the ligation-treated group were anesthetized with sodium pentobarbital (30 mg/kg, iv). A longitudinal anteromedial incision was made in both proximal thighs of each rabbit to expose the nutrient artery, which was ligated on one side. Rabbits in the control group received neither anesthesia nor operation.
Bone imaging.
Bone scans were performed on the day of operation, and on the 4th, 9th, 12th, 16th, and 20th days after operation. The animals were not anesthetized and were positioned supine on the scanning table. The hind legs were extended and rotated slightly externally so that they were placed symmetrically and directly under the collimator of the gamma camera (GZB, Ministry of Aeronautics and Astronautics Industry, Beijing), which was connected to a computer for storage of the imaging data on a magnetic disc.
Dynamic and static scans were included in the bone scintigraphy. At time zero, a bolus injection (74MBq/kg body wt) of 99mTc methylene diphosphonate (99mTc: Nuclide Research Institute, Sichuan; MDP: Red Flag Pharmaceuticals, Shanghai) was given in a rabbit ear vein, and the computer immediately recorded dynamic scans, comprising serial 3-sec images for 60 sec. After 4 hr, the computer recorded the static scans of the hind legs. Dynamic and static scans were obtained for all rabbits in the control and ligation-treated groups.
Scan analysis.
GCCS-89 software (Qinghua University, Beijing) was used to analyze the scans. The shaft and the upper and lower metaphysis and epiphysis (ME) of the femur and tibia were selected as the regions of interest (Fig. 1
). The mean radioactivity (counts/sec) per pixel in each region of interest and the ratios of radioactivity counts on the ligated side vs the contralateral side were calculated.
View larger version (23K):
[in this window]
[in a new window]
|
Fig. 1. Dynamic bone imaging of the bilateral hind limbs of a rabbit at 1 hr after ligation of the nutrient artery to the right femur. The blocks with white outlines delineate the regions of interest, comprising the shaft and the upper and lower metaphysis and epiphysis of both femurs and tibias. The white arrow points to the shaft of the right femur. Note a significant reduction of the radionuclide uptake (99m-Tc-MDP) in the shaft of the right femur, compared to the contralateral femur.
|
|
Statistics.
ANOVA and the Newman-Keuls test were used to compare the count ratios at serial time-intervals post-operation; Student’s t-test was used to test for significant differences between corresponding means in the control and ligation-treated groups. Each data set was tested for normality and homogeneity of variance, to satisfy the requirements of ANOVA.
|
Results
|
|---|
Table 1 lists the mean ratios for radioactivity counts of one side to the other side on the dynamic scans and static scans of tibias of the control group and of the treated group post-ligation of the femoral nutrient artery. These data show that ligating the femoral nutrient artery did not affect the blood supply of the tibia. There were no significant differences of blood supply between the tibias of the control and ligation-treated rabbits.
View this table:
[in this window]
[in a new window]
|
Table 1. The ratios of the radioactivity counts in one tibia to the concurrent radioactivity counts in the contralateral tibia of the same rabbit. (n = 6 rabbits/group; mean ± SE).
|
|
After femoral nutrient artery ligation, the radioactivity counts of the shaft, the upper ME, and the lower ME were reduced significantly on day 1. The resumption of blood supply was speedy, since the values on day 4 were significantly increased compared with those on day 1 (Table 2).
View this table:
[in this window]
[in a new window]
|
Table 2. The ratios of the radioactivity counts in the ligated femur at the specified time post-operation to the pre-operative counts in the same femur. (n = 6 rabbits/group; mean ± SE).
|
|
The dynamic scans showed that the radioactivity counts of the shaft and the two ME of the ligated femur decreased significantly at 1 hr post-operation, were close to the normal level on day 4, and exceeded the contralateral level slightly on days 9 and 12. The reductions of the count ratios in the 3 bone segments were different, being greatest in the shaft, intermediate in the upper ME, and lowest in the lower ME. The ratios returned to normal on day 16.
The static scans showed that the radioactivity counts of the 3 bone segments were reduced on day 1, exceeded the contralateral level on day 4, continued to increase at 9 days, came down at 12 and 16 days, and returned to normal at 20 days. The sequential alterations of the dynamic and static scans were similar but not identical; the values of the static images consistently exceeded those of the dynamic images on days 1 to 12.
|
Discussion
|
|---|
The retention of the bone-seeking radionuclide in bones is influenced by the bone blood flow and by the nature of the bone matrix [6,7]. The bone blood flow is the most important factor in dynamic bone scans, while the static bone scans reflect both factors [6,8]. Recent experimental studies confirm that radioactivity counts of dynamic bone-imaging over the first min after iv injection of the radionuclide are an indicator of osseous blood flow; the static bone scans do not exactly reflect the bone blood flow, since they are also influenced by the bone matrix [8–11].
In our experiment, dynamic bone scans showed that radionuclide uptake of the 3 bone segments of the ligated femur decreased significantly at 1 hr post-operation; the mean reductions of the count ratios were greatest in the shaft, intermediate in the upper ME, and lowest in the lower ME (0.66, 0.74, 0.81, respectively; p <0.05). The count ratios were close to normal on day 4 (0.96, 0.98, and 1.02, respectively; p >0.05), increased slightly at 9 and 12 days, and returned to normal on day 16.
The experimental results showed that the progressive changes of the static scans were similar to those of the dynamic scans, but the reason why the count ratios of the static images exceeded those of the dynamic scans is unclear.
As dynamic bone imaging during the first min post-injection is an indicator of osseous blood flow, the significant decrease of radionuclide uptake at 1 hr post-ligation shows that the nutrient artery is important for the normal bone blood supply. The finding that the blood supply of the nutrient artery was different in 3 bone segments is consistent with a previous study [12]. The mechanism whereby blood flow of the ligated femur recovered rapidly at 4 days is probably the compensatory dilatation of the other bone arteries. Previous studies showed numerous anastomoses among the 3 bone arteries, so that if blood flow in one artery is impaired, flow in the other arteries increases [13–16]. This compensatory mechanism requires intact anastomoses. The results of the present study are consistent with these observations.
The blood supply of the ligated femur exceeded the contralateral level at 9 and 12 days, probably because the nutrient artery ligature caused ischemic injury of the ligated femur, which led to an inflammatory response and resulted in an increase of the bone blood supply. Because ligating the nutrient artery caused ischemic injury of the 3 bone segments to varying degrees, the increases of blood flow and the recovery times were different (Table 2
). As the radioactivity counts of the region of interest comprised the entirety of the bone and associated soft tissues, counts from the soft tissues were added to both the ligated and contralateral femur. A method to correct for the soft tissue counts needs further investigation.
In summary, the blood flow of the bone nutrient artery is an important part of the whole bone blood supply, and injury to the nutrient artery leads to a decrease in the bone blood flow. However, so long as anastomoses among bone vessels are intact, the recovery rate is speedy and long-term disorders of the bone blood supply do not ensue.
|
References
|
|---|
- Cuthbertson EM, Siris E, Gilfilian RS. The effect of ligation of the canine nutrient artery on intramedullary pressure. J Bone Joint Surg Am 1964;46:781–788.[Medline]
- Grundnes O, Reikeras O. Acute effects of intramedullary reaming on bone blood flow in rats. Acta Orthop Scand 1993;64:203–206.[Medline]
- Lopez-Curto JA, Bassingthwaighte JB, Kelly PJ. Anatomy of the microvasculature of the tibial diaphysis of the adult dog. J Bone Joint Surg Am 1980;62:1362–1369.[Medline]
- Rhinelander FW. The blood supply of the limb bones. In: Scientific Foundations of Orthopaedics and Traumatology (Owen R, Goodfellow H, Bullough PG, Eds): Heinemann, London, 1980; pp 127–150.
- Strachan RK, McCarthy I, Fleming R, Hughes SP. The role of the tibial nutrient artery. Microsphere estimation of blood flow in the osteotomised canine tibia. J Bone Joint Surg Br 1990;72:391–394.
- Lavender JP, Khan RA, Hughes SP. Blood flow and tracer uptake in normal and abnormal canine bone: comparisons with Sr-85 microspheres, Kr-81m, and Tc-99m MDP. J Nucl Med 1979;20:413–418.[Abstract/Free Full Text]
- Paradis GR, Kelly PJ. Blood flow and mineral deposition in canine tibial fractures. J Bone Joint Surg Am 1975;57:220–226.[Medline]
- Nutton RW, Fitzgerald RH Jr, Kelly PJ. Early dynamic bone-imaging as an indicator of osseous blood flow and factors affecting the uptake of 99mTc hydroxymethylene diphosphonate in healing bone. J Bone Joint Surg Am 1985;67:763–770.[Medline]
- Aronson J. Temporal and spatial increases in blood flow during distraction osteogenesis. Clin Orthop 1994;301:124–131.
- Hughes SP, Lemon GJ, Davies DR, Bassingthwaighte JB, Kelly PJ. Extraction of minerals after experimental fractures of the tibia in dogs. J Bone Joint Surg Am 1979; 61:857–866.[Medline]
- Nutton RW, Fitzgerald RH Jr, Brown ML, Kelly PJ. Dynamic radioisotope bone imaging as a noninvasive indicator of canine tibial blood flow. J Orthop Res 1984; 2:67–74.[Medline]
- Shim SS, Copp DH, Patterson FP. Measurement of the rate and distribution of the nutrient and other arterial blood supply in long bones of the rabbit. J Bone Joint Surg Br 1968;50:178–183.
- Johnson RW Jr. A physiological study of the blood supply of the diaphysis. Clin Orthop 1968;56:5–11.[Medline]
- Nelson GE Jr, Kelly PJ, Peterson LF, Janes JM. Blood supply of the human tibia. Am J Orthop 1960;42:625–636.
- Rhinelander FW. The normal microcirculation of diaphyseal cortex and its response to fracture. J Bone Joint Surg Am 1968;50:784–800.[Medline]
- Rhinelander FW. The normal circulation of bone and its response to surgical intervention. J Biomed Mater Res 1974;8:87–90.
Top
Abstract
Introduction
