femoral loosening, all of which showed a lucent zone or black line between ..... a fixed supero- lateral triangle of radio-opaque cement and a curved femoral.
LOOSENING
OF
THE
FEMORAL
COMPONENT
AFTER
TOTAL
HIP
REPLACEMENT THE
THIN
MARK
BLACK
PATERSON,
Froni
Review
of the
LINE
radiographs
PHILIP
Queen
of 882
A lexandra
consecutive
AND
THE
SINKING
FULFORD.
ROBIN
Hospital,
HIP
DENHAM
Portsmouth
metal-to-polyethylene
hip
replacements
after
a mean
follow-up of 6.8 years showed 72 cases (8%) of aseptic femoral loosening, all of which showed a lucent zone or black line between metal and cement. In 97% of the series this appeared within two years of the arthroplasty. Progress of loosening was unpredictable and only 24% had significant symptoms. Improved technique with methylmethacrylate cement in Stanmore prostheses had reduced loosening after two years from 7.9% to 0.4%. Methods of detection of early loosening are discussed.
Total
hip
replacement
is one
of the
most
successful
and
rewarding operations ever developed. It provides good early results in over 90#{176}/of cases and most of these will last for 7 to 10 years (Dobbs 1980). The most common cause of late nent (Harris,
failure is loosening of the femoral McCarthy and O’Neill 1982).
A number
ofpapers of the femoral
loosening reported
incidence
ranges
compo-
I I % (Harris
et a!. 1982)
.
to 36% (Carlsson and Gentz 1980) or even 50% at 5.8 years (Ling ci ii!. 1981 ). Most of this large variation stems from diflering radiological and clinical definitions of loosening and varied length of follow-up, but there are also real differences related to the wide range of prostheses and the techniques of insertion. A number of radiological features of the usually painless early loosening of the femoral component have been described. These include 1975),
fractures subsidence
in the cement ofthe prosthesis
Amstutz
1979),
and
or zones
at the
interface
the
(Weber (Gruen,
appearance
and Charnley McNiece and
of radiolucent
of cement
and
adjacent
metal
lines (Carlsson
to the superolateral
femoral prosthesis (Fig. I). A number
one
surgeon
performed
by
It is usually
and
Registrar El IBB.
P. C. Fulford, (‘J’O. 3 Bankside, Alverstoke,
Orthopaedic P012 2NH.
R. A. Denham, Queen Alexandra 3LY. England. Requests ( . 1986 0301
392
OBE, MChOrth, FRCS. Gosport. Hampshire
A total
FRCS. FRCSEd, Consultant Orthopaedic Surgeon Hospital, Cosham, Portsmouth, Hampshire
for reprints should he sent to Mr J. M. H. Paterson. British Editorial Society of Bone and Joint Surgery
620X
86 3047
S2.00
greater
Surgeon England. P06
(RAD).
We
have
of a consecutive replacements, Follow-up
of
all this
studied in the natural
of symptoms.
of
882
AND
total
hip
MATERIALS
replacements
between 1974 and Hospital, Alton,
Portsmouth.
posterolateral
England.
methods.
of their films were then was made to determine
METHODS
Hospital, J. M. H. Paterson. FRCS. SeniorOrthopaedic The London Hospital, Whitechapel. London
the
no large comprehenhas been reported
consistent
surgeon
of the
history of these black lines and any other associated changes. The lines were almost invariably symptomless when first seen, and it was possible to review factors which might influence the incidence both of radiographic
consecutively Mayor Treloar
loosening.
one
and the full series detail. An attempt
in all or most
ofmechanical
using
stem
radiograph radiographic
series is from 3 to I I years (mean 6.8 years) and there has been excellent co-operation from the patients, with over 95% attending for their six-year review. A narrow lucent zone or “black line” between metal and barium-loaded cement was seen in one or more radiographs of 72 of these patients. Their case histories
changes
cases
ofthe
examined the records and radiographs series of 882 metal-to-polyethylene hip
Gentz 1980). It is agreed by most authors that a radiolucent line or zone between radio-opaque cement and the stem of the prosthesis is a useful early sign which will be present
and
curve
on an anteroposterior of papers discuss
changes and their significance, but sive series with reasonable follow-up from
describe series ofcases in which component had occurred. The from
seen
1982 and
All operations
approach
without
were
performed
by RAD at Lord Queen Alexandra were
by a standard
osteotomy
of
the
trochanter.
Operation. The femoral component was cemented, and from 1974 to 1979 40g of barium-loaded CMW cement was inserted by “thumbing” into a cavity prepared with rasps. From 1980 to 1982 the femur was more thoroughly prepared,
with
a meticulous THE
JOURNAL
routine OF BONE
in which AND
JOINT
the
use
SURGERY
of
OF THE
LOOSENING
FEMORAL
COMPONENT
AFTER
films
TOTAL
were
HIP
studied
393
REPLACEMENT
as they
became
available,
to confIrm
the diagnosis and to assess any changes. Thirteen hips which had suffered gross loosening secondary to deep infection (I .5% of882) were excluded from the series. The lucent zone. The radiographs of the 72 hips which showed a black line were studied in detail, and the size of the radiolucent zone in each film was measured vertically in the line of the medial border of the stem of the prosthesis (Fig. 2). A transparent scale and a hand lens were used
and
observers measurement. between sumed
the and
metal direction
results
were
and cement, of subsidence
increases the sensitivity ofthe sised that this measurement “width” of the lucent measurement decrease graphic magnification Fig.
I
Fig.
2
Figure 1 Radiograph to show radiological loosening of a Stanmore prosthesis 1 sears after operation. The lucent zone or “black line” is seen between the cement and the superolateral part ofthe femoral component stern. Figure 2--Diagram to show the measurement of the lucent zone in the line ofthe medial border ofthe stem ofthe prosthesis.
rasps and technique of the Krause.
curettes to clean
was followed the remaining
hone (Halawa ci Krug and Miller
used to improve (Hankin ci a!.
was carefully
placed dried
had produced to ensure that
absolutely
still
until
in the before
has been used. Routine review. radiographically one year. two anteroposterior
an increase the prosthesis
the cement
9 to 10 minutes. In the early part
of
Charnley prosthesis Stanmore prostheses series ended in 1982,
was were a new
All patients six months
had
the
hardened
period
were after
reviewed operation years a few
3.
\1\’i
reported,
preand
result. It should be emphais not the more usual In no series of films did this time. Differences in radioassessed by measuring the
greater
component in each of large differences in the was made in the than
2 mm.
Magni-
fication of the image was also checked on a number films by comparing the known diameter of the prosthetic head with the diameter of its image on the radiographs.
of
Subsidence. An effort was made to detect and record any subsidence of the metal prosthesis in relation to the hone of the femur itself. Subsidence was obvious in all the cases of severe loosening. but attempts to measure this accurately failed to provide repeatable results.
1956
a
clinically and and then at thereafter. The days of opera-
review appointment were specially filed sequence of radiographs for each hip together. and at each review a search
of even a very narrow lucency was radiographs were then re-examined. No
to the prosthesis
completely
being
ance vious
B.
zones
of this interval
in viscosity. Care then remained
made f’r the presence of a black line cement at their superolateral junction.
68
of lucent
different
medullary cavity being filled with
and
VOl
approximates of the
apparent length ofthe whole metal a series of films. Where there were size of this image, an adjustment measurement
by direction shortest
used in 164 hips; later. used in 718 hips. Since this Denham femoral component
years. and every two films taken within
tion and at each so that the full could he displayed was
1981; was
zone. with were
The the
cement from a gun. This cement mass was manually and the stem of the femoral prosfIrmly into the cement mass after early poly-
nierisation was taken after
1978: Lee and Ling 1982). Hydrogen peroxide
a!.
lining
cleaning and secure better haemostasis 1984). A plastic cement excluder of the
Hardinge pattern which was then SOg ofCMW pressurised thesis thrust
by a “scrub-squirt-suck” coarse cancellous
repeatable
at different times. while magnifying
between metal The appearnoted
and preSubsequent
Fig.
3
Fig.
4
Radiographs at 21 years and M years after a Stanmore hip replacement to show the difficulties of measuring subsidence against bony landmarks. In this very obvious case. despite definite loosening. the prosthesis has apparently risen in relation to a line drawn from the top of the greater trochanter at 90 tO the shaft of the femur. The differing magnification. a flexed position and sonic rotation (evidenced by the lesser trochanter) have all contributed to the optical illusion.
394
J. M. H. PATERSON,
P. C. FULFORD,
R. A. DENHAM
RESULTS
Lucent zones. Not one of the 72 hips showed a lucent zone or black line in the film taken within a few days of operation. The black lines seen in later review radiographs varied from 0.5 mm to I 7 mm in vertical size (mean 3.3 mm). The rate of increase of these lines varied from zero to 3 mm per year (mean 0.6 mm per year). This change could
-
this
time after
operation Fig.
S
Diagram relating the width of the lucent zone to the time after operation: records of 72 cases superimposed. Group A show rapid early progression and have all undergone reision. Group B have small. sloss I progressive OF temporarily stationary Iuccnt zones. and few have sn1pton1s.
There
were
four
main
reasons
cantly points
the radiographic on the femur and
for this.
prosthesis
(Figs
graphic
3 and
projection
sible points “pelvis for
4).
altered
for both
the
as men-
between of the image
Third.
measurement. hips” gave
First,
magnification of the could be corrected by of the head. Second, found to alter signifi-
relationship the edges
difference
relationship A film different
often
or obscured the lesser degree It was
the tip of the greater by heterotopic trochanter were
of rotation reluctantly
“fixed” of the
in
radio-
between centred results
repeatable
measurements
sible only from standard positions radio-opaque time
ofthe
Other made
was
accurate,
radiographs taken and projections, placed
in the
variation
signs years
vi
indistinct of the and
would
be
pos-
prospectively or by the
use
with of a
femoral
of loosening. The onset of pain is related to time in in Figure 6. which shows that only 17 hips (23.6%
bone
time after
at the
Fig.
loosening. of films
and especially developing
any between
noted, as were any indications tion ofthe stem. Records. The clinical records
Careful to detect
and
in the cement. and bone were or valgus
and Wessex
computer
of those
angulacards
operation
(years)
6
Diagram relating the first radiological sign of loosening and the onset ofsymptoms to the time since operation. Note that 970/0 of cases had a lucent zone or black line by two years,
examination was other progressive
fractures cement ofvarus
stability
than 97% of the cases in this series had declared themselves: only two of the 72 sinking hips first showed a black line later than two years after operation. Pain and loosening. The onset of pain was nearly always considerably delayed in relation to the early radiographic
operation. of set
between
pos-
reliable
of subsidence
marker
features of each
changes. Lucencies
trochanter
that
the rate of increase Figure 5 illustrates
to show from one
bone. while the contours influenced too much by
of the femur. concluded
unpredictable
and way.
at the two-year follow-up. Time since arthroplasty. The first appearance of a black line was related to the time since arthroplasty (Fig. 6). Almost one-third of the series had shown a black line at the first review only six months after operation. This line was usually very narrow, and nearly always symptomless. Two years after insertion of the prosthesis, no less
centred over one hip. Finally, efforts to find a satisfactory point on the bone ofthe upper femur from which to measure subsidence failed to produce repeatable results. Too
apparently
uniform, either
and deterioration. With reference to the clinical symptoms, it was interesting to note that in 7 ofthe 12 patients who had already had revision operations the radiographic luccnt zone had been under 2 rum in vertical size
(years)
tioned above, there was variable radiographic image. although this reference to the known diameter variation in femoral rotation was
was far from alter dramatically
toms. zone
that
only
with
Pain (Table
24#{176}/a of
lucent correlates I) and
patients symptoms.
zones)
have,
have,
as
as yet,
yet.
developed
developed
symp-
well with both the size ofthe lucent with the rate of increase in size of the
for all 72 patients were examined to confirm the details of operative technique and the onset, severity and course of symptoms which might be referable to loosening. Note was made of patients who were awaiting, or had already
lucent zone (Fig. 7). Thus, no patient among 50 in whom the lucent zone was less than 4 mm had yet experienced significant pain, while only 5 of the 22 patients with a lucent zone larger than 4 mm were pain-free. Similarly, no
undergone.
patient among at an average
loosening.
revision
arthroplasty
for pain
attributable
to
43 in whom the lucent zone had increased of 0.4 mm per year or less had yet experiTHE
JOURNAL
OF BONE
ANt)
JOINT
SURGERY
L(X)SENING Table without zone
I. The pain
Width
oflucent
number related
OF THE
of
patients width of
to
FEMORAL
COMPONENT
with and the lucent
AFTER Table lucent
TOTAL
HIP
395
REPLACEMENT
II. The position of the zone. rate ofdeterioration
prosthesis related to and presence of pain Position
Less
than
4
ione
Pain-free
3
6 7 iim
I
iim
8
and
1
over
Total
55
Mean
width
7
Mean
rate ofincrease
8
Number(#{176}/o)withpain
graphs
soon.
All
had
black
lines
did not develop af’ter arthroplasty.
was
I .8 mm
significant
within
two
significant The mean
in pain-free
hips.
years,
but
and
8.2 mm
four
of
(i;im)
was
there
any
The
of the
mid-zone
ZOne
in those
with
ofthe metal prosthesis was itself sometimes
pain-free
U
cement within
painful
20
12
evidence
commonest
ofcement Failure
revealed
0
tion ofthe x-ray beam. Attitude of the prosthesis.
10 12 14 16 18 20 22 24 26 28 30
rate of increase
of lucent zone (mm/year)
relate
the
rate
ofincrease
ofthc
lucent
zone
to the
presence
of pain.
Fractures of the cement. Definite fractures, other than the lucent zone. could be seen in the radio-opaque cement in only 19 hips. 26% of the series. These transverse black lines were seen most often around the middle third of the stem of the prosthesis. In seven of these cases the fracture was seen to widen as the lucent zone increased in width, confirming. in these cases at least, that while the proximal cement did not move, the distal cement subsided with the metal stem. These fractures were usually seen in association with the larger lucent zones. though this was not always the case. which showed lucent In
none
of
Table
Ill.
of those
No fracture zones larger
the The
which
72
sets
number
(‘ham/er pro.st/1(’.se.s Number of hips Number with lucent .Staii,,iorc
B.
No
of
visible 6 mm.
in six hips
anteroposterior and
radio-
Stanmore
demonstrated
prostheses
radiological
oped
only
zones
10 I
98 26
42 8
zones
94 6
12 2
50 4
when
to the
a wider
was
a fracture
progressive
sinking
cement mass, is a combination
3.
MAY
of hips with lucent
986
which of’
ci a!. (1979), that within some of the
of the remaining away from
cement and stem the fixed supero-
was the cause to see a fracture
ofthe lucent zone in the cement in
this
plane
coincided
The
femoral
lucent
(Table II). The widening ofthe
alignment
shaft
in the
with
the
dinec-
of the prosthesis first
film
was
neu-
zone
that
the others
at the time
of re-
significance of this is uncertain since the zone is probably a product ofboth subsi-
dence and increasing medial drift or varus displacement ofthe prosthesis (Carlsson and Gentz 1980). Type of prosthesis. Although fewer in total number, Charnley prostheses had been used in exactly half the cases that developed black Charnley femoral component inserted
in each
1977
1976
of failure slowly
view (5.8mm as against 2.9mm) and also had a higher incidence of pain and a more rapid rate of deterioration
of loosening
1975
tn-
tral in 62 cases, varus in nine cases and valgus in only one. The radiographs of 72 randomly selected unloosened hip replacements showed much the same distnibution of alignment. However, the loose prostheses which were in a varus position from the beginning had devel-
signs
1974
of the
year
ofthe
1978
1979
3 1
I 0
110 4
94 11
period
under
lines (Table III). Thus, became loose in 22.8% review,
and
the number
1982
Total
1980
1981
0 0
4 0
0 0
0 0
158 36
88 8
114 1
106 0
43 0
711 36
J)ro.st/ie.se.s’
Number Number
68
was than
ofCharnley
subsequently
4(44%)
of the cases was probably because, while could be in any plane. it would be clearly
in relation
7
with
and movement bone. Movement
4
tO
I3(2/%)
Ia and lb ofGruen of the metal stem
three-quarters the fracture
I)iagrani
1.01
and the distal fractured. This
8
Fig.
0.54
of movement
mode
cement,
lateral triangle or black line.
08
5.8
angular block of cement which forms the superolateral boundary of the lucent zone, nor any significant lucency at its interface with the bone inside the greater tro-
the modes offailure is, both pistoning
02 04 6
(n=9)
2.9
(mmir)
chanter.
16
VOl
zone
eight
pain.
24
-
of lucent
until lucent
symptoms size ofthe
28 vi QJ vi
the
17
enced pain. while only 12 out of29 patients with rates of increase greater than 0.4 mm per year were pain-free. Fwelve patients have so far had revision arthroplastics for painful hips, though others will require this them \cars
of
Varus Neutral (n = 62)
0
4 5 iim
width
of prosthesis
Painful
50
illiTi
the
the of
396 cases
J. M. H.
compared
with
5. 1 %
of the
PATERSON,
Stanmore
P. C. FULFORD,
R. A. DENHAM
prostheses.
As Illost of the Charnley prostheses were inserted during the first three years ofthe study. it might be expected that later technical iniprovements unrelated to prosthesis design were responsible fcr the different incidence of loosening of these two prostheses. However, Table III shows that Stanmore prostheses inserted during these early years were less likely to loosen than the Charnley prostheses. \ear of operation. The number of arthroplasties which developed a black line varied greatly from year to year (Table 1975.
Ill). In the earlier years of the study, particularly this was probably a reflection of the relatively poor
results 1977
with
the
onwards,
Charnley
diflerences
cannot he attributed only 8 out of 563
prosthesis. in the
However,
incidence
to the design arthroplasties
from
ofblack
lines
of the prosthesis since were of the Charnley
pattern. striking
A
occurred Stanmore 1979 had Stanmore years
decrease
in
the
incidence
of
loosening
from 1980 onwards. Twenty-three of 292 arthroplasties (7.9#{176}/o) performed from 1977 to a black line at two years; only one of 263 arthroplasties (0.4#{176}/o) showed this feature two
after
dramatic improved
operation change methods
performed
from
coincides with of cementing.
1980 the
to 1982.
This
introduction
the upper diagrams
The appearance of a black line between a fixed superolateral triangle of radio-opaque cement and a curved femoral stern seems to he a useful sign ofearly loosening. It is commonly symptomless. hut as a warning sign itjustitles special follow-up. ifonly to ensure that revision can he considered before there is serious loss of bone stock. use of radio-opaque cement and review with at two years may be important in this this is strongly advised.
Unfortunately. radiolucent, and
more
8
of a Denham replacement with a in the hone of the femur.
of
DISCUSSION
The routine radiography respect. and
Fig. Radiograph straight-stem metal marker
this sign is absent when cement importantly. when a straight-stem
is
femoral to show
shaft. Weber and Charnley present improved support after movement of
the distal cement mass with its metal stem; Ling’s Exeter prosthesis was designed to re-stahilise after minor subsidence. This concept has not been supported by this series of 72 hips with radiographic loosening. The rate of widening of the lucent zone was unpredictable and very variable. There were several cases in which a narrow black line, recognised within a year of arthroplasty and stable rapidly
for a number and became
plateau in this
ofloosening series is not
of years, then painful. Coventry
deteriorated (1981)
between 5 and 10 years. Follow-up yet long enough to be certain whether
prosthesis is used. Under those circumstances. a direct measurement of any subsidence of the prosthesis in relation to bone would be useful. In our series this could not, in retrospect. be accurately measured. Clarke ci a!.
or not this is the case, but Figure 5 suggests oration is unpredictable even after five years. The relationship between lucent zones toms is very similar to that reported elsewhere.
(1976a,b) reported similar difficulties in assessing the wear of acetahular components and devised special jigs to ensure that films were centred accurately. Care with radiographic projection will help. but it seems best to
patients mean
mark metal
the hone at the greater trochanter slug (Fig. 8). A special introducer
with has
a small been
reported
with black follow-up by DeSmet.
Carlsson
taken
dramatic reduction which has followed
Ling thesis mantle
at intervals It has been ci
a!.
1981)
after the operation. suggested (Weber that
a suitably
can subside with to a new position
part of ofstahility
and designed its
Charnley femoral
1975; pros-
damaged cement within the funnel of
and
of this degree. The most
that
deteni-
and sympOfour 72
lines, 76% remained symptom-free of 6.8 years. paralleling the Kramer
and
77% of Carlsson and Gentz zones of4mm or more, 77% and Ilstnup (1978) reported
designed which adds only a few seconds to operating time: any movement of the prosthesis will then be easily detected by comparison of standard single-hip films
quite found a
Gentz
feature in the
(1977)
and
the
(1980). Of hips with lucent were painful: Beckenbaugh 56% with symptoms. and reported
( I 980)
striking
Mantel
at 79%
50%
of this
early use of
study
radiographic improved
for subsidences has
been
the
loosening techniques of
cementing. With the older methods, black lines, if they were to appear. had usually become evident by two years. Since the new techniques have been used, only one THE
JOt!RNAL
OF
BONE
AND
JOINT
SURGERY
