femoral head blood flow in femoral neck fractures - Bone & Joint

FEMORAL

HEAD

FEMORAL

AN

ANALYSIS

M.

HARPER,

50 patients

M.

Glenfield

with fractures

R.

General

of the femoral

FLOW

IN

FRACTURES

INTRA-OSSEOUS

From

We studied

NECK

USING

W.

BLOOD

PRESSURE

BARNES,

P.

Hospital,

neck,

MEASUREMENT

J.

GREGG

Leicester

33 intracapsular

and 17 extracapsular.

Intra-

osseous pressure was measured by a transducer within the bone to quantify blood flow, and intracapsular pressure by a needle introduced into thejoint space. The mean intracapsular pressure was lower in the extracapsular fractures. In these, the mean intraosseous pressure in the femoral head was unchanged by aspiration of the joint. However in the intracapsular fractures aspiration produced a significant decrease in intra-osseous pressure and an increase in pulse pressure within The results blood The

major

femora!

flow by relieving complications neck

avascular

the femoral head. suggest that aspiration

are

necrosis.

of intracapsular

haematoma

produced

of intracapsular failure

of

Avascular

fixation, necrosis

may

fractures

of the

nonunion

and

be caused

by

PATIENTS We

studied

extracapsu!ar pacted or minimally measurements were

arterial

pressure recorder.

pressure

alone,

but

the two; it can be shown to parallel relationship between bone blood pressure has been 1964; Shim, Hawk cannot reflected

demonstrated and Yu 1972);

be made in this way by changes in pressure.

a combination

in animals direct flow

but

changes

in

W. M. Harper, FRCS Ed, Smith and Nephew Trauma Fellow, Department ofOrthopaedic Surgery M. R. Barnes, BSc, Senior Physicist, Department of Medical P. J. Gregg, FRCS, MD, Professor of Orthopaedic Surgery UniversityofLeicester SchoolofMedicine, Glenfield General Groby Road, Leicester, England. Correspondence

should

be sent

to Mr

©

W. M.

1991 British Editorial Society of Bone 0301-620X/91/1071 $2.00 J Bone Joint Surg [Br] 1991 ; 73-B :73-5.

VOL.

73-B,

No.

1, JANUARY

1991

of

bone blood flow. The flow and intra-osseous

and

Harper. Joint

Surgery

(Azuma measures flow

are

Research Physics Hospital,

AND

50 patients

damage to the retinacular vessels at the time of fracture or, possibly, by the tamponade effect of an intracapsular haematoma (Soto-Hall, Johnson and Johnson 1964; Kristensen, Kiaer and Pedersen 1989). We have investigated the vascularity of the femoral head following proximal femoral fractures, using intra-osseous pressure as an indicator of bone blood flow. Intra-osseous pressure is not a measurement of or venous

an increase

in femoral

head

tamponade.

1 7 were

the fracture was multiple cannulated

with

METHODS proximal

and 33 displaced made under fixed, either screws.

femoral

fractures:

intracapsular (nine imand 24 displaced). All anaesthesia and before by

a sliding

screw

or

Intracapsularpressure was measured with a 125 mm, 1 8 G spinal needle and three-way tap attached to a 1 50 cm manometer tube. This was connected to a Gould P50

insertion

transducer and then to an The system was flushed of the

needle.

Pressures

amplifier and chart with saline before were

measured

with

reference to a zero level with the tap open to atmosphere and placed at the level of insertion of the needle. The joint space was approached anterolaterally, guided by image intensification. After all readings had been taken, the intracapsu!ar placement of the needle was confirmed by injection of 1 ml of radio-opaque dye (Niopam). For displaced fractures, pressures were measured after the fracture had been reduced, which often required the leg to be internally rotated, whilst in the remainder the pressures were measured with the hip in neutral position. The hip was not moved during the pressure recordings. Intra-osseous pressure was measured with a purpose-built stainless steel probe 2 mm in diameter.

(Gaeltec Ltd) 120 mm in length The pressure sensor was 2 mm

and from 73

W. M. HARPER,

74

the tip ; it faced sideways. This catheter-tip records the pressure at the site of interest intermediate manometer tubing and taps. The can then

be zeroed before insertion correct with respect to

M. R. BARNES,

P. J. GREGG

transducer with no transducer

; all measurements atmospheric pressure.

are A

standard transducer/catheter system would have made it very difficult to establish an accurate zero reference, because of uncertainty as to the position of the end of the

Fig.

catheter inside the femoral head. Another advantage of the method is that the size, shape and rigidity of the probe makes it easy to introduce through a guide wire hole, while its radio-opacity makes it possible to achieve precise amplifier

placement. The transducer and chart recorder to

recordings. In each central guide confirmed

hip, the probe wire channel

by image

Table II. aspiration

Readings

Changes ofthejoint

pressu

and

taken

pulse

pressure

and

offluid

Intracapsular n=33

38.13 SDl7.6l

6.84 SD4.36

Extracapsular n = 17

38.43 SD 13.52

8.14 SD 4.94

femoral

head

pulse

before

pressure

and

Mean

After

Difference

Before

After

Difference

4.56 SDI1.8

5.l8t SD5.9

5.84t SDS.79

0.65 SD 1.72

Extracapsular n = 17

49.06 SD 18.3

49.94 SD 19.9

0.88 SD6.2

7.94 SD4.4

7.82 SD4.62

0.12 SD 0.48

0.038

used

pressures paired

were

measured

before and intracapsular

after aspiration (Table II). fractures, the mean pressure

from the joint. There were no significant differences in the mean or pulse pressures recorded in either type of fracture in the trochanteric region (Table I), or in the femoral head (Table II). In extracapsular fractures, there were no significant differences in the mean or pulse pressures in the head

pre&sure

However, in in the femoral

head fell by 4.56 mmHg and the mean pulse pressure rose by 0.65 mmHg following aspiration (Table II); these changes are statistically significant for both mean pressure (p = 0.037) and for pulse pressure (p = 0.038).

t-tests.

was difficult to quantify because once the had been perforated there was a slow leak

pulse

(mmHg)

40.4l SD2O.0

0.037

region

after

Before

tP

trochanteric

pressure

44.97 SD26.8

The mean intracapsular pressure before aspiration was 23.07 mmHg (SD 39.1) in extracapsular fractures, and 30.03 mmHg (SD 47.48) in intracapsular fractures. The hip was aspirated with a 20 ml syringe until the intracapsular pressure fell to zero. The exact amount of aspirated cortex

in the femur

Intracapsular n = 33

*p

recording.

Mean

Mean

RESULTS

blood lateral

pressure of the

Fracture

intra-osseous

testing

neck

pressure

Fracture

in the

re(mmHg)

from the trochanteric region and from the head before and after aspiration of the hip. From the readings the pulse pressure was taken as the amplitude between the maximum and minimum of the waveform, and the mean pressure as the mid-point between them (Fig. 1). Intracapsular

I. Intra-osseous fracture of the

after

the was

were

in mean space Mean

simultaneously. Statistical

Table

is connected to an provide permanent

was inserted through and its placement

intensification.

Intra-osseous

1

DISCUSSION Intra-osseous pressure measurement has been used by other authors as a means of measuring bone blood flow (Azuma 1964 ; Shim et a! 1972), but earlier methods were restricted by technical shortcomings. The method we describe, using a catheter-tip pressure transducer, has the advantage that the pressure sensor is in direct contact with gave

the site to be measured. far greater reproducibility

This

technique in our hands.

An initially surprising finding was intracapsular pressure in some extracapsular should

the

increased fractures.

Theoretically

there

but these fractures are almost always a fall, and local trauma may produce an therefore less surprising that some of these develop an effusion or a haemarthrosis. standard deviations in the results are a

OF BONE

bleeding

and

joint space, produced by effusion. It is patients may The large

THE JOURNAL

be no direct

is easier

AND

JOINT

into

the

SURGERY

FEMORAL

feature

of all work

makes

direct

However, reproducible place,

involving

intra-osseous

comparison in

each if the

as in our

are altered and will be reflected

between

individual pressure

study.

HEAD

BLOOD

pressures

individuals

subject is recorded

Therefore

if external

will

cause

an increase

Crawfurd

in pressure;

in the joint reach levels

et al 1988)

cavity, after an sufficiently high

that

sustained increases levels no higher than

Stromqvist

et

al

sular neck,

abolition

fractures

However,

there

pulse

in

our

pressure

fracture, may the flow of blood

series that

where has

the

been

capsule

little

intracapsular high

intracapfemoral intraintact.

evidence

in man

that these intracapsular pressures can stop or decrease the bone blood flow to the femoral head. Stromqvist et a! (1988) showed indirectly, using bone scanning techniques, that some femoral heads had an increased uptake following may have 24

aspiration influenced

hours

after

Kristensen aspiration intracapsular not

VOL.

aspiration

However, : the hips

and

after

other factors were scanned osteosynthesis.

et al(1989) showed increases in P02 following of the hip in two of nine patients with fractures, but intracapsular pressures were

measured. The fall

73-B,

of the hip. this result

No.

mean

I, JANUARY

intra-osseous

1991

of intracapsular

being

due

by removal the associated

to relief

fractures of an

of an intracapsular increase in pulse

as showing

an increase

after of the

may

initial

be

venous

haematoma. pressure may

in bone

add further evidence that an in the presence of a damaged

circulation ischaemia

blood

flow.

intracapsular intra-osseous

an intracapsular fracture, may cause femoral head which can be reversed by

aspiration of the joint. If this is to prevent death, then it should be performed as soon

osteocyte as possible

the fracture.

We acknowledge the assistance of the Smith and Nephew Research Foundation, Richards Medical and Glaxo Laboratories. Although none ofthe authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, foundation, educational institution, or other non-profit institution with which one or more of the authors is associated. REFERENCES Azuma

pressure

that

H. Intraosseous pressure as changes in bone marrow. Angio/ogy

we

a

measure of haemodynamic 15:396-406.

1964;

Crawfurd EJP, Emery RJH, Hansell DM, Capsular distension and intracapsular fractures of the femur. J Bone Joint Surg

Shim 58, Hawk marrow 353-60.

HE, Yu WY. cavity pressure

Phelan M, Andrews 8G. pressure in subcapital [Br] 1988 ; 70-B :195-8.

NW. Intraosseous P02 in femoral of blood flow after aspiration of fractures. Acta Orthop Scand 1989;

The relationship of bone. Surg

between blood flow and Gyneco/ Obstet 1972 ; 135:

Soto-Hall R, Johnson LH, Johnson RA. Variations in the intra-articular pressure of the hip joint in injury and disease : a probable factor avascular necrosis. J Bone Joint Surg [Am] 1964; 46-A :509-16. Stromqvist B, Nilsson LT, Intracapsular pressures neck. J Bone Joint Surg

Egund

N, Thorngren

in undisplaced [Br] 1988 ; 70-B

K-G, fractures :192-4.

in

Wingstrand H. of the femoral

Svalastoga E, Kiaer T, Jensen PE. The effect of intracapsular and extension of the hip on oxygenation of the juvenile epiphysis: a study in the goat. J Bone Joint Surg [Br] B :222-6.

pressure femoral 1989; 71-

Swiontkowski MF, Tepic 5, Perren SM, Moor R, Ganz R, Rahn BA. Laser Doppler flowmetry for bone blood flow measurement: correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow. J Orthop Res 1986; 4:362-71. Vegter

in

as

75

Kristensen KD, Kiaer T, Pedersen neck fracture ; restoration hemarthrosis in undisplaced 60:303-4.

is probably

direct

aspiration

Our results haematoma,

after

work with juvenile Vegter and Lubsen 1989) has shown that

0 to 200 mmHg. good evidence

obstruction Similarly,

FRACTURES

(Soto-Hall

pressures can occur after fractures of the more particularly in relatively undisplaced

capsular

pressure : venous

changes in the femoral head. well above diastolic have been literature (Crawfurd et a! 1988;

1988);

pressures varied from There is therefore

after

be interpreted this

in intracapsular pressure, even to 40 mmHg in the rabbit, can produce

hypoxia and ischaemic Intracapsular pressures reported in the clinical

NECK

interpreted

are same

of the

increased

intracapsular to obstruct

to the femoral head. Experimental animals (Swiontkowski et a! 1986; 1987 ; Svalastoga, Kiaer and Jensen

report

conditions

of arterial flow will be reflected by abolition pressure (Azuma 1964). It has been suggested by various authors et a! 1964;

; this

blood flow, pressure.

In individual cases changes in intra-osseous probably do reflect changes in bone blood flow obstruction

IN FEMORAL

difficult.

the values from the

cause a change in bone by changes in intra-osseous

FLOW

J, Lubsen epiphysis after study in juvenile

CH.C. Fractional transient increase rabbits. J Bone

necrosis of injoint pressure Joint Surg [Br]

the femoral head : an experimental 1987 ; 69-B :530-5.