Acta Orthopaedica Scandinavica
ISSN: 0001-6470 (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/iort19
Effect of physical activity on muscle and bone
blood flow after fracture: Exercise andtenotomy
studied in rats
Oliver Grundnes & Olav Reikerås
To cite this article: Oliver Grundnes & Olav Reikerås (1991) Effect of physical activity on muscle
and bone blood flow after fracture: Exercise andtenotomy studied in rats, Acta Orthopaedica
Scandinavica, 62:1, 67-69, DOI: 10.3109/17453679108993096
To link to this article: https://doi.org/10.3109/17453679108993096
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Acta
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Orfhop Scand 1991: 62(1): 67-69 - -~
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Effect of physical activity on muscle and bone
blood flow after fracture
Exercise and tenotomy studied in rats
Oliver Grundnes and Olav ReikerAs
In male Wistar rats, a transverse osteotomy of the production were also recorded. There were no dif-
midshaft of the left femur was performed. The rats ferences in bone or muscle blood flow between the
were allocated to three groups: 1) one that under- three groups. An increase in total bone and muscle
went a 4-week training program 4 weeks after the blood flows was seen on the osteotomired side. In
osteotomy, 2) one that had a tenotomy of the left weight-bearing rats, the callus area was more vas-
Achilles tendon to prevent weight bearing, and 3) cular as compared with the diaphyseal bone. No
one that had normal function and activity. Eight correlation between callus mass and callus flow
weeks after the osteotomy, total bone, proximal was found. Our results support the concept that
diaphyseal, callus, and muscle blood flows were blood supply is mandatory for fracture healing;
measured using the microsphere technique. Initial however, other factors seem to be decisive for the
and final body weights, bone weight, and callus rate of healing.
..
Department of Orthopedics, Institute of Clinical Medicine, UIniversity Hospital, N-9012Tromse, Norway
The current concept of fracture healing is mainly drill and starting from the osteotomy site-produc-
based on two variables: stability and blood supply. ing proximal and distal fragments) to a diameter of
In experimentally fractured bones, normal function 1.5 mm. The burred residue was not rinsed out. A
and full weight bearing accelerate bone healing 1.6-mm-diameter steel pin was used for intra-
(Sarmiento et al. 1977, Terjesen and Svenningsen medullary nailing, and finally the wound was closed
1986, 1988). in two layers.
Our present study was designed to evaluate the In the nonweight-bearing group, the ipsilateral
effect of different degrees of activity and weight Achilles tendon was cut just proximal to its insertion
bearing on muscle and bone blood flows in a site. Thus, although these rats were permitted full
fractured long bone. mobility of the limb, weight bearing was impossible.
To prevent the Achilles tendon from regaining its
function, a new tenotomy was performed 4 weeks
after the first operation. The animals in the control
and exercise groups resumed partial weight bearing
Material and methods
a few days postoperatively, and full weight bearing
The study was performed on 30 male Wistar rats was regained after approximately 2 weeks. Tenoto-
(MgllegArd Avlslaboratorium, Eiby, Denmark) mized rats moved their operated on limb with ease;
weighing 326 (313-340) g. The rats were assigned however, weight bearing was insufficient throughout
to either an exercise, a nonweight-bearing, or a the experimental period, as was intended
control group. After intraperitoneal anesthesia Four weeks after the osteotomies, the exercise
(fentanyl-fluanisone, 0.1 mL/lOO g body weight), group started their training program in a dark room
the left femur was exposed between the lateral on a treadmill with a 10 percent set inclination. Both
vastus and hamstring muscles. A partial transverse the treadmill speed and the duration of training were
osteotomy at the midshaft of the bone was gradually increased until the rats were running 2
performed with a fine-toothed circular saw blade h/day at a speed of 20 m/min.
mounted on an electric drill, and then the bone was Eight weeks after the osteotomy, bone and muscle
manually broken. A periosteal elevator was passed blood flows were measured using the microsphere
underneath the middle part of the femur, as is done technique (Morris and Kelly 1980). A polyethylene
for protection of the soft tissues when performing catheter (PE-50) was led through the carotid artery
osteotomies. The medullary cavity was successively and placed in the aortic root for injection. Radio-
reamed (using steel burrs mounted on the electric labeled microspheres (New England Nuclear, I4'Ce)
68 Acta Orfhop Scand 1991: 62(1): 67-69
of 15 f 0.05 pn diameter were used, and each Table 1. Total bone and muscle blood flow (mUminxl00 9.’)
in the exercise, nonweight-bearing, and control groups 8
injection consisted of 350,000 spheres suspended in weeks after osteotomy. Median (25-75 percentiles)
0.9 percent saline. The distal artery was cannulated
with a polyethylene catheter (PE-10) and connected Fractured Nonfractured
to a Harvard infusion-withdrawal pump for refer- side P-value side
ence sampling at a rate of 195 mL/min. The super-
Bone blood flow
ficial layers of the vastus lateralis were used to Exercise group 29 (20-43) c 0 005 14 (6 8-27)
measure muscle blood flow. This muscle consists of Nonweight-
mixed red and white fibers, which minimize the bias bearing group 24 ( 1 3-58) Z.0 005 11 (5 G26)
Control group 27 (12-32) < 0 005 8 9 (7 0-20)
concerning diversion of the blood flow between red
Muscle blood flow
and white muscle fibers after exercise. Exercise group 14 (9 8-26) NS 9 7 (5 6-23)
Finally, the animals were killed, and the left and Nonweight-
right femurs were dissected free from all the soft beannggroup lO(99-19) NS 17 (10-38)
Control group 9. (6.615) NS 6.6 (3 2-1 7)
tissue and then dried and weighed. The frontal and
transverse diameters of the callus mass were meas-
ured with a sliding caliper, and the quantity of the
callus was expressed as the cross-sectional area,
Table 2. Fractional bone blood flow mUmin x 100 9.’ in the
assuming it to be an ellipse. The bones were placed exercise, nonweight-bearing, and control groups 8 weeks
in counting vials together with the reference samples after osteotomy. Median (25-75 percentiles)
and counted in a Pacard Auto-Gamma Scintillation
Spectrometer. Total bone flow was first determined, Proximal
after which a proximal diaphyseal part and the callus diaphysis P-value Calius area
area were separated for fractional blood flow Exercise group 27 (17-34) < 0 005 72 (36-88)
estimates. Nonweight-bearing
For statistical evaluations, we used the nonpara- group 29 ( 1 8 4 1 ) 0.09 50 (21-87)
Control group 26 (14-37) < 0 005 43 (27-58)
metric Kruskal-Wallis test, comparing several
means. To evaluate differences between the two
limbs, we used the Wilcoxon rank-sum test. P <
0.05 was considered significant. Data are presented
with medians and 2.5-75 percentiles. Muscle blood flow did not differ in any group
(Table 1). The flow ratio between the fractured side
and the control side showed a 17 percent increase in
muscle blood flow to the operated on side in the
ResuIts nonweight-bearing group, and 28 percent and 20
percent, respectively, in the exercise and control
The weight gain in the exercise group was 152 groups ( P = 0.05).
(132-172) g, which was 31 percent less than the
increase found in the control group ( P < 0.05).
No differences in total bone blood flow were
found between the three groups. The total fractured
bone blood flow was increased in all three groups
Discussion
(Table 1). Further, no differences were found in the The lower weight gain in the exercise group was
fractional bone blood flow between the three groups. deemed sufficient to confirm the effects of the
In the exercise and control groups, the blood flow training program (Forwood and Parker 1986,
was increased in the callus area when compared Sommer 1987).
with the diaphyseal bone, whereas the difference in The present method using radioactive micro-
the nonweight-bearing group was not significant spheres for bone-blood flow measurements is well
(Table 2). established (Morris and Kelly 1980, Tondevold and
The external callus area was 61 (53-82) mm2 in Biilow 1983, Li et al. 1989). In our study, the osteo-
the exercise group, 79 (53-93) mm2 in the non- tomies were pinned after reaming the medullary
weight-bearing group, and 80 (71-106) mm2 in con- cavity, with destruction of the intramedullary
trol group. No statistical differences were found. vessels and part of the corticalis (Dankwardt-
Regression analysis showed no correlation between Liliestrom et al. 1969). This induced damage stim-
callus area and callus blood flow (Y = 0.1612). ulates periosteal osteogenesis, as is reflected in the
Acta Orthop Scand 1991: 62(1): 67-69 69
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increased total bone blood flow. Sim et al. References
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