P. THOMAS,. I. G. TURNER,. C. B. JONES. From the. Westminster. Hospital and the Royal. National. Orthopaedic. Hospital,. London. Four types of prosthetic.
PROSTHETIC
ANTERIOR IN
From
the
A COMPARISON
OF
NEIL
P. THOMAS,
Westminster
Hospital
Four types of prosthetic Dacron composite, Dacron
All the knees
showed
intra-osseous
bony
portion,
incorporation
first
use
of a prosthetic
TYPES
I. G.
the
OF
TURNER,
Royal
Zealand white were examined
REPLACEMENT
C.
National
B. JONES
Orthopaedic
Hospital,
London
cruciate ligament (carbon fibre, carbon fibre and were assessed at three, six and 12 months after
rabbits. The synovium and both intra-articular macroscopically, by light microscopy and
and there was no significant
Dacron
the
of its outer
80 years ago, but it is only have been used in significant
FOUR
LIGAMENTS
growth
and intraby scanning
into the intra-articular
part of
and xenograft did not appear to be suitable materials in this animal model. The short-term ingrowth of fibrous tissue only into the periphery of the sheath in its
whereas
was they
RABBIT
and
mild synovitis,
The
THE
replacement for the anterior alone and bovine xenograft)
implantation in the knees of New osseous portions of the ligaments electron microscopy. any ligament. Carbon fibre composite ligament showed
CRUCIATE
ligament
showed
progressive
fibrous
tissue
ingrowth
with some
fibres.
anterior
cruciate
in the last numbers.
ligament 15 years that This arises
partly from the increased frequency of anterior cruciate ligament injury and consequent disability, and partly from dissatisfaction with the results of autologous repair operations for instability. The latter often require a long rehabilitation period and rate at five years (Odensten,
may have Lysholm
Friedman et al. 1985). A wide range of materials augment the anterior cruciate polydioxanone, trafluorethylene,
few
is available ligament.
nylon, polypropylene, Dacron (polyethylene
polyester, carbon fibre, and various combinations are
a 30% to 40% and Gillquist
reports
of the
failure 1983;
to replace or These include
expanded polyteterepthalate) or
tendon or ligament xenografts, of synthetic materials. There results
of animal
experiments
and
Fig. The
four
carbon
prosthetic fibre/Dacron
clinical N. P. Thomas, Basingstoke RG24 9NA,
FRCS, Consultant District Hospital, Park England
Orthopaedic Prewett,
Surgeon Basingstoke,
Hampshire
I. G. Turner, PhD, Lecturer in Biomedical Engineering Institute of Orthopaedics, Royal National Orthopaedic Brockley Hill, Stanmore, Middlesex HA7 4LP, England. C. B. Jones, Westminster England. Requests
©
FRCS, Senior Orthopaedic Hospital, Horseferry
for
reprints
should
be sent
Editorial Society $2.00
to Mr
of Bone
N. and
in the study: carbon fibre
conflict.
We
a,
b,
bovine xenograft; tow; d, Dacron.
have
examined
the
response to four different prosthetic materials knees with emphasis on intra-articular and reactions.
MATERIALS SW 1 P
2AP,
The
P. Thomas. Joint
often
c,
Hospital,
four
in Figure
1987 British 030l-620X/87/2041
312
Registrar Road, London
data
biological in rabbits’ intra-osseous
ligaments used composite;
1
Surgery
each carbon
types
AND
of prosthetic
METHODS
ligament
we used
are shown
1.
The carbon fibre of 5000 filaments
ligament comprised three of uncoated, high-strength
tows, dry
fibre.
THE
JOURNAL
OF BONE
AND
JOINT
SURGERY
PROSTHETIC
Fig. Scanning osseous collagen material
ANTERIOR
CRUCIATE
The
terephthalate
comprised
uncoated, high-strength dry carbon drawn into a braid of ICI terylene
polyester. with an
Each S-twist
Eight
filaments
of
fibre. This delustered
end consisted of 92 filaments assembled and each ply consisted of 92 filaments
assembled with a Z-twist. The approximately 15 p. The polyethylene terephthalate was of 4 mm high-strength type,
filament
diameter
(Dacron)
with
each
was
ligament tip tubed in
polyethylene for easy insertion. The outer sheath was a tube of knitted, double-velour Dacron sewn at four corners to give an “H”-beam envelope which contained a core
of four woven Dacron tapes. The xenograft was a bovine tendon whose intermolecular cross-links had been treated with The
resultant
stabilised
cally resistant to mechanical, degradation, and it was claimed biological prosthesis. In all, 24 female New between six and 1 2 months
collagen
was
natural glutartheoreti-
Zealand white rabbits were used, six for each
of age type of
using 4% fluothane mixture. The fur and
the
skin
General
by mask, was shaved
prepared
with
anaesthesia
was
and maintained from the right aqueous
induced
with lower
chlorhexidine.
a 2% limb A
medial parapatellar incision and approach allowed the patella to be dislocated laterally. The anterior cruciate ligament was identified and excised. Drill holes were made in the femur and tibia at the “anatomical” attachments and the prosthetic ligament was introduced. It was sutured with unabsorbable sutures at the exit of the drill holes, in moderate tension with the knee in 1 5#{176} of flexion. A dressing was applied and the leg held in an elastoplast dressing for 10 days. VOL.
69-B.
appropriate, was used, microscopy
NO.
2, MARCH
1987
killed
at each
of three, two
fibre/Dainto the in the top
six and
I2
animals
in
were and
made of intra-
of the synovium, eosin and, where
Miller’s stain. Conventional with the addition of scanning for the majority of the sections.
microscopy electron
RESULTS Carbon fibre.Intra-articular. completely in its intra-articular
less
marked the
cuffapproximately carbon fibre bone almost months this
individual this
I 50 p and
the
400
p
thick
and
surrounded the carbon cuff approached the tow fibres and groups of them
matrix,
and fibrous were seen
“neoligament” and six-month but this was
but
some
fibres
were
implant. The carbon and were infiltrated
tissue, but in the tissue presence
fibre/Dacron
was growing a fibrous-tissue
600 p thick between the bone and the 2). At six months this layer appeared
(Fig.
the site of the more separated
despite Carbon
ligament had ruptured portion in all six animals
at 12 months. At three months collagen carbon fibres and there was
Intra-osseous.
into
The
was no evidence of any The synovium in the threeshowed heavy carbon staining,
to be between
ofoperation.
were
osseous course. These, and sections were stained with haematoxylin and
between
ligament.
Technique
rabbits
portion of a carbon fibroblastic ingrowth bone can be seen
months from operation so that there were each ligament/time subgroup. Transverse and longitudinal sections each ligament in both its intra-articular
and there formation. specimens
chemical and biological that it would form a true
3
Transverse section of the intra-osseous cron ligament at three months showing outer Dacron fibres (lower left). Normal right corner (Miller’s stain x I I).
composite
40 000
the same tow was
aldehyde.
313
RABBIT
Fig.
carbonfibre/pth’ethvlene
ligament)
IN THE
2
electron micrograph of a transverse section of the intraportion of a carbon fibre ligament at three months showing A, growing between the fibres: and B, the thick cuff of fibrous between the carbon tow and the surrounding bone ( x 120).
(Westminster
LIGAMENTS
a cuffof
lamellar
fibre tow. At 12 more closely. Both were incorporated seen fibres with
remote had fatty
from become marrow
no complete haversian systems growing into the carbon fibres
of the
cuff
composite
of lamellar
(Westminster
bone.
ligament).
Four ligaments were intact, one had an incomplete rupture at six months, and one a complete rupture at 12 months. Where there had been a rupture, Intra-articular.
N. P. THOMAS,
314
I. G. TURNER,
C. B. JONES
Fig. 4 Scanning osseous surface around
the
electron micrograph of a transverse section of the intraportion of a carbon fibre/Dacron ligament at 12 months. The of the ligament shows a layer of fibrous tissue (A) contoured the outer Dacron sheath (B) ( x 180).
synovium
other normal
Fig. 5
was
specimens with mild
heavily
stained
the synovium synovitis on
with
carbon.
In
the
was macroscopically microscopy.
Scanning electron micrograph of a transverse section of the intraosseous portion of a Dacron ligament at six months. There is diffuse infiltration
was was
of the
outer
(
sheath
x
macroscopically normal, present microscopically A
Intra-osseous.
intervals.
There
27).
though a mild in all specimens.
similar picture was no ingrowth
synovitis
was seen at all time into the ligament, and a
At three months the fibroblastic material seen around the prosthetic sheath was confirmed to be collagen by Miller’s stain (Fig. 3). There was a little microscopic ingrowth; this was confirmed by scanning electron microscopy. There was no progression at six
synovial lining was frequently seen at the interface between ligament and bone. At 1 2 months the ligament could easily be lifted from its bony canal, though in one specimen there was a profuse fibroblastic proliferation of
months and at 1 2 months seen to conform to rather polyethylene terephthalate
tissue into the outer at one year showed the ligament from
Intra-osseous.
the fibrous tissue sleeve was than to penetrate the sheath of (Fig. 4).
Dacron. Intra-articular. Four specimens were intact, and two had sustained small partial ruptures. At six and 12 months a white film of variable thickness covered the ligament but there was no evidence of significant ingrowth. The synovium was macroscopically normal, though microscopy showed mild non-specific inflammatory blood vessel Intra-osseous.
tic tissue
changes formation.
such
as hyperaemia
At three months there ingrowth into the periphery
and
part ofthe ligament. a continuous fibrous the bone (Fig. 8).
The micrograph layer separating
DISCUSSION The materials use and their the reaction
tested in this study have all been in clinical biocompatibility has been established, but to each of them was different.
increased
had been fibroblasof the sheath, the
outermost fibres being spread apart by fibrous tissue with some prosthetic fibres embedded in bone. At six months the ligament was enveloped in a richly vascular connective tissue with multinucleate giant cells and macrophages while its outer coat had become more diffusely infiltrated by fibrous tissue (Fig. 5). At 12 months there was almost complete dispersion of the fibres at the interface with a continuation of ingrowth which seemed to push apart but not penetrate the central tapes. Although this ingrowth was not bony in nature, some of the outer fibres were incorporated in bone (Fig. 6). Bovine xenograft. Intra-articular. Three ligaments were intact and three showed partial rupture. No ingrowth had
occurred
in any
specimen
(Fig.
7). The
synovium
Scanning electron micrograph osseous portion of a Dacron penetration of fibrous tissue
THE
of a transverse section of the intraligament at 1 2 months. There is extensive between the tapes ( x 24).
JOURNAL
OF
BONE
AND
JOINT
SURGERY
PROSTHETIC
The
mechanical
strength
and
ANTERIOR
biological
CRUCIATE
inertness
LIGAMENTS
IN THE
315
RABBIT
of
were the features responsible for its initial choice by Jenkins, who showed its potential as a biodegradable ligament scaffold at extra-articular sites in sheep (Jenkins et al. 1977). Some workers have coated the carbon fibre for easier handling and to prevent early carbon
fibre
degradation (Alexander et al. 1982; Weiss et al. 1985) while others have used it in an extra-articular position to augment an autologous repair (Lemaire 1985). It has not been clearly established whether “neoligament” formation could reliably occur in an intra-articular situation (Jenkins 1985; G#{244}recki, Ku and Salomon 1986). The
safety
of
has
Dacron
been
confirmed
by
20
years’ experience in cardiovascular surgery (Turner, Hoffman and Weinberg 1982). The observation that dense fibrous tissue grew into vascular grafts instigated a modification in their structure which resulted in im-
Scanning osseous
proved
fibrous
strength,
and
this
material
was
tested
as
a
electron micrograph portion of a xenograft
layer
ingrowth
natural
the ligament
( x
from
1985).
within
the
graft
Short-term (Abbink has not
indicates
of the intraa continuous
the surrounding
material,
anterior the bony
clinical and been
bone.
and
cruciate tunnels
No
bovine ligament (McMas-
successes
have
Kramer 1986), though as satisfactory (Good,
Gillquist 1985, unpublished The finding ofgeneralised
knees
section showing
30).
used to replace the incorporated within
reported follow-up and
seen
clefts
xenograft had been ter
separating
was
of a transverse at 1 2 months
a response
data). synovitis
in these
to foreign
was variable but always present. there was less response to liberated
been longer Odesten rabbits’
materials
which
It was interesting carbon fibre after
that one
year than at three months. No carbon fibre was found in any of the lymph nodes examined. All four prosthetic ligaments showed a disappointing amount of tissue ingrowth into their intra-articular portions, indicating that this articular
behaviour is much sites. Within the bony tunnels
long-term Fig. Anterior showing
potential Lesker
7
view ofa xenograft in situ no covering or ingrowth.
and ingrowth, fibrous although
at six months,
prosthetic ligament (Meyers, Grana 1979). It is now recommended for augmentation
and
of a repair rather than as a replacement (Park, Grana and Clitwood 1 985). The Westminster composite prosthesis was developed in response to initial disappointment with
intra-articular
carbon
Jones and Thomas covering would breakage the ment”
of
and
allow
fibrous
on
its own
It was thought that a Dacron the carbon fibre from early tissue
to penetrate
prosthesis, enabling the formation this hypothesis was to be tested.
to the core of a “neoliga-
biological progressive Xenografts 69-B.
developed as a answer to the reported reactions and the deterioration of synthetic polymers in vivo. are said to be invaded by host tissue along the tendons
NO.
2.
MARCH
or
ligaments
1987
were
likely
fixation
Response
was
when it occasional
occurred, areas
slow
than is a key with
was of bony
at
extra-
factor
in
all materials predominantly ingrowth were
seen. Fibrous tissue invaded the carbon fibre, but was virtually absent in the xenograft and did not progress in the composite Westminster ligament. Further comments on these findings should await mechanical testing of the bone-ligament-bone system. The Dacron coat of the Westminster ligament has now been given a more open weave for clinical use.
(Aichroth,
;
Xenografl
VOL.
1986). protect
fibre
results.
less
small
The scope of our study was limited by the use animal and some work with larger animals
started, can that
so that be tested. uncoated
for the failure
prostheses From carbon
anterior cruciate to produce
disintegrates. synovium may worry
of the
standard
our preliminary work fibre is not a suitable ligament, mainly a “neoligament”
“human”
of a has size
we consider replacement because of its before it
The long-term effects of carbon on the are probably benign though the appearance the surgeon at re-operation (Rushton, Dandy
316
N.
P.
THOMAS.
and Naylor 1983). Bovine xenograft appeared relatively little reaction at either intra-articular osseous
The
sites
outer
ligament
after 1 2 months, except coat of the composite
even Dacron
appeared
to have
too
tight
I. G.
to produce or intrain one animal. Westminster
a weave
to allow
adequate ingrowth at either site, so the basic design hypothesis remains untested. The Dacron ligament showed progressive fibrous tissue ingrowth at least into its sheath in its intra-osseous part, though the intraarticular response was variable. Before there is even more widespread clinical use of intra-articular prosthetic replacements for the anterior cruciate ligament, we consider that their biological and mechanical properties should be more fully investigated. The placing of these materials under weight-bearing conditions in heavy demands reaction, creep,
but and
an intra-articular on them, not only also
bending
in the
mechanical
environment places in terms of biological factors
of strength,
fatigue.
TURNER,
C.
Jones CB, Thomas NP. Carbon fibre and in the prosthetic reconstruction of the anterior J Bone Joint Surg [Br] 1986:68-B:841.
Alexander H, Parsons JR, Smith G, Fong R, Mylod A, Anterior cruciate ligament replacement with filamentous Proceedings of the 28th Annual Orthopaedic Research New Orleans, Louisiana, 1982:45.
MJ, Sherman OH, RJ. Autogenic anterior
Friedman
struction
of the
knee:
Dacron cruciate
Weiss AB. carbon. Society,
Fox JM, Del Pizzo W, Snyder SJ, cruciate ligament (ACL) anterior a review. C/in Orthop 1985:196:9-14.
Ferkel recon-
G#{243}reckiA, Ku, Salomon Z. ACL reconstruction with carbon fibres in animal experiments. In : Trickey EL, Hertel P. eds. Surgery and arthroscopv ofthe knee. First European Congress of Knee Surgery and Arthroscopy, Berlin 1984. Berlin etc: Springer-Verlag, 1986:238.
DHR.
Jenkins
Orthop
Ligament
induction
by filamentous
carbon
fiber.
C/in
1985:196:86-7.
Jenkins DHR, Forster 1W, McKibbin B, RiliVs ZA. tendon and ligament formation by carbon implants. Surg [Br] 1977:59-B:53-97.
Induction J Bone
Lemaire
with
M.
fibers:
Reinforcement four
McMaster WC. substitution 196:196-201.
years
tendon
and
C/in
Orthop
cases.
ligaments
carbon
1985:196:169-74.
A histologic assessment of canine with bovine xenograft. C/in
Odensten M, Lysholm distal iliotibial instability. C/in Park
anterior Orthop
cruciate 1985:
J, Giliquist J. Long-term band transfer (DIT) Orthop 1983:176:129-35.
for
follow-up study anterolateral
of a knee
JP, Grana WA, Clitwood JS. A high-strength Dacron augmentation for cruciate ligament reconstruction : a two-year canine study. C/in Orthop 1985:196:175-85.
N, Dandy
histological ligament 308-9.
REFERENCES Turner
Weiss
of 1300
of Joint
JF, Grana WA, Lesker PA. Reconstruction of the anterior cruciate ligament in the dog : comparison of results obtained with three different porous synthetic materials. Am J Sports Med 1979:7:85-90.
Rushton
Abbink EP, Kramer FJK. Preliminary report on the use of bovine xenograft in knee instability problems. In: Trickey EL, Hertel P, eds. Surgery and arthroscopv ofthe knee. First European Congress of Knee Surgery and Arthroscopy, Berlin 1984. Berlin etc: Springer-Verlag 1986:241.
JONES
Aichroth PM, composites ligament.
Meyers The authors would like to thank Mr E. L. Trickey for providing the impetus necessary to initiate the study, Mr P. M. Aichroth for his encouragement and the Westminster Hospital Orthopaedic Department Research Fund for financing the project. We greatly appreciate the facilities provided by Professor H. Ellis and his Surgical Unit at the Westminster Hospital and particularly Ms Marketa Dickinson for her painstaking work on the histological sections. Our thanks are also due to Dr Branfoot for his help in interpretation of the histology, Mr J. Greenough for help with the illustrations and Professor J. T. Scales for his general co-operation.
B.
DJ, Naylor findings after with carbon-fibre.
CPE. The clinical, arthroscopic and replacement of the anterior cruciate J Bone Joint Surg [Br] 1983:65-B:
RJ, Hoffman HL, Weinberg SL. Knitted Dacron double velour grafts. In : Stanley JC, ed. Biologic and synthetic rascular prostheses. New York etc: Grune & Stratton, 1982: 509-22.
AB, Blazina ME, Goldstein replacement with an absorbable early clinical experience. C/in
THE
JOURNAL
AR, Alexander copolymer carbon Orthop 1985:196:77-85.
OF
BONE
AND
H. Ligament fiber scaffold:
JOINT
SURGERY
