S.I.O.T. 2007; 33(suppl.1) : 8238-8242
ACL Reconstruction Using Artificial Ligament:
Five Years Follow Up
G. Cerulli et at.
Summary: Aim of the study was to evaluate the results of anterior cruciate ligament reconstruction
with Lars® artificial ligaments at a five-years follow-up.
25 patients have undergone anterior cruciate ligaments reconstruction using synthetic tissue and the
all-inside surgical technique. The operation was proposed to symptomatic, motivated subjects who
needed quick recovery to return to sport or working activities.
For the individual clinical evaluation the VAS, KOOS and IKDC forms were used. An expert neutral
"observer examiner" performed the objective clinical evaluation. The subject also had a biomechanical
functional assessment: arthrometrical, isokinetics and stabilometrical.
The subjective clinical evaluation, which result from the assessment forms used, shows positive
results in over 90% of the cases. Similar results were observed following the objective clinical
evaluation. The biomechanical evaluation showed excellent or good recovery in the majority of cases.
The authors conclude that Lars® artificial ligaments are, in carefully selected cases, a valid alternative
to the autografts and allografts.
Key Words: graft, synthetic tissue, anterior cruciate ligament, all inside technique
Introduction: In the second half of the 90'S the artificial ligaments started again to be taken into
account in the anterior cruciate ligaments reconstruction. The new artificial ligament was accepted
from most of the orthopedics surgeons with skepticism in consideration of the bad experiences of the
80's. In the next years a better knowledge of the causes of failures and an analysis of the literature
took us and other orthopedics surgeons to consider again the possibility of using the synthetic tissue
as graft. This choice came out based on the following considerations:
.. Not all the cases operated in the 80's were failed: some subjects had good subjective and
objective results even after a long year follow up, such as some patients operated with
artificial ligament made of Dacron and clinically evaluated in the 2000 from our group;
.. Multifactor causes are responsible for the failures of the ACL reconstructions, such as the
surgical technique which was more aggressive and less accurate and the structural
organization of the materials used;
.. The improvement of the surgical techniques more accurate and less invasive;
.. The experience of the surgeon and of the Industry that made better surgical instruments and
new advanced materials;
.. The consideration that autografts and allografts commonly used are not the best solution
.. The structure and the organization of the new artificial ligament generation as well as the
mechanics characteristics: the high resistance to the traction force
.. The results, at short term follow up, that carne up at the end of the 90' and at beginning of the
2000 from the international literature using the synthetic ligament as graft in the human,
especially the absence of post-op synovitis and the recovered knee stability, with satisfaction
of the patients.
We have been started in the 2001 using the new Lars® synthetic ligament in ACL reconstruction in
well selected cases: subjects over 40 yrs old, symptomatic, motivated, with a need of faster recovery
and with short time to spend for the rehabilitation. In a second phase and in special cases, such as
the chance of the life or for personal motives we reconstructed the ACL with the synthetic graft in
patients less the 40 yrs old.
After the first cases, where we used the bi-tunnel out-in technique with metallic interference screws as
fixation device, we started using our new technique named all-inside technique. This technique works
very well with the artificial ligament since it is less invasive (saving of bone and soft tissue) and with a
double fixation system in the bone tunnels: press-fit and interference, using special titanium screws
modified at the extremities made by Lars®. The post-op protocol it is not heavy for the patient: elastic
band for the first week, range of motion of the knee not limited from the day after surgery; a faster
rehabilitation program for recovering muscles strength and proprioception'. The full recovery time for
returning to sport and work activities is shown to be around 30-40 days. The post-op protocol was the
same for all the patients involved in the study.
Materials and Methods: We have been checking a group of 25 patients, operated in the 2002 of ACL
reconstruction with synthetic ligament. All patients have been evaluated at the end of the 5 yrs follow
up. The exclusion criteria on patient selection were: lesion of the ACL and PCL at the same time;
lesion of the contra lateral ACL and with previous or next reconstruction of the contra lateral ACL. The
group took into account did not have other problems that could affect the results of the ACL
reconstruction.
We evaluated 7 female and 18 male with a mean age of 46 yrs (min 30 yrs, max 60 yrs). The mean
weight was 75,6 kg (min 54 kg, max l13kg), while the mean high was 174 cm (min 160 cm, max 187
cm).
The left side was interested in 13 cases and the right side in 12.
For the subjective clinical evaluation have been used different forms:
.. The VAS scale, to quantify the subjective pain of the operated knee, through a standard
scale, with a score from 0 (no pain) to 10 (maximal pain). The subject was invited to cross out
with a pen the score that better represented his pain;
.. The KOOS, which is a form to evaluate many subjective parameters such as: symptoms
(swelling, limitation of the R.O.M.); stiffness of the knee (in the morning and during the day),
pain (during the rest or daily activities), daily activities (walking, getting up from the bed, going
up and down stairs, dressing etc), sport activities (bending on the knees, running, jumping,
cutting off, squatting), quality of the life in relation to the knee (change of the lifestyle, no trust
on the operated knee). The patient had to cross the spots that better represented the answer
to each question.
.. The IKDC (International Knee Documentation Committee), which is a form that, with a score,
put in evidence the limitation of the patient into the daily and sport activities, and symptoms
associated. The maximal score is 100 (excellent) and shows the better healthy condition in
terms of limitations and symptoms, a score under 100 allows to make 4 groups of evaluation:
optimum; good; quite good; bad.
The clinical evaluation of the knee was done from a Blind Observer, well known orthopedic surgeon
and researcher: Prof. R. Lorentzon from University of Umea (Sweden). He has evaluated different
parameters of the operated knee in comparison to the contra lateral: R.O.M. (full or partial, for deficit
of flexion or extension), knee swelling. He has then performed specific tests to look at the knee
stability and ACL
functions:
.. Lachman test, using the following criteria for the evaluation: (--negative); (+- slightly positive);
(++- moderate positive); (+++ positive)
.. Pivot shift test, with the same scale for the evaluation (---; +--; ++-; +++) and the same
judgment for the knee instability, (no instability, slightly, moderate, high instability)
The same observer has also evaluated, side to side, the muscles trophysm at the level of the thigh,
measuring 10 cm from the base ofthe patella using the following evaluation scale: no ipotrophysm,
slightly ipotrophy « 1cm), moderate ipotrophy (between 1 and 2 cm), severe ipotrophy (> 2cm).
At the end of the evaluation, Prof. Lorentzon gave his personal judgment on the clinical status for
each patient: excellent, very good, good and bad. We decided to add at the clinical evaluation also a
biomechanical functional assessment to achieve and quantify infonnation regarding the knee stability,
muscle strength and the capability to the position control. The biomechanical evaluations have been
performed in the lab Let People Move in Perugia.
The arthrometical analysis of the knee stability was done, side-to-side, using a KT 2000, getting data
at 15-20-30 Libras and at manual maximum. Three trials were performed for each patient and the
average of those was taken into consideration. For the evaluation of the knee stability, we looked at
the values obtained at 30 Libras and at manual maximum (universally recognized as more significant
values) and we considered three groups, based on the data acquired side to side: group a) 2mm and 4mm (bad), the last group is to be
considered as instable knee and as a failure of the ACL reconstruction. The muscle strength of the
knee extensors and flexors was tested with an isokinetic machine: the Kin-Com. The exam was
performed side to side, in concentric at the speed of90/sec. and with a knee excursion ranged from
10° to 90°. The values obtained of the pick of strength of the flexors and extensors on the operated
knee were put in comparison and expressed in percentage as well as the data recorded from the
flexors and extensor side to side.
To look at the capability to control the position, a stabilometric analysis has been perfonned using a
force platform (Bertec), with rectangular shape and dimension of 40cm X 60cm. The patient was
invited to stand on one leg in the middle of the platform, without shoes and with a slight flexion of the
knee (30°), for 10 sec., with specific software the data were acquired and analyzed and a graphic
elliptic representation of the oscillation area was obtained. Also for this test the comparison was done
side to side. More is wider the elliptic area, less in the capability to control the position and of course
worst is the result.
Results: The 25 patients were invited to participate to this study by a phone call, all of them was
enthusiastic to get in the follow up, that behavior was for us a positive sign in terms of compliance of
the patients, since in 2002 we proposed to those patients the new generation of the synthetic graft for
the ACL reconstruction combined with the new-all inside technique.
Regarding the work activity of the cases studied we found a wide variety of jobs: from the
housewives, employers, to the medical doctors. The level of activity can be considered: IKDC IV
(sedentary), in the 32% of cases; type III (not heavy manual work and not straining sport activity such
as running; gym; swimming; cyclette) in the 40% of cases, while in the 28% of the cases the
functional needs, job and sport related were higher. In particular regarding the sport activity, we tested
a high level athlete who has been judged in the study as excellent result. 20% of the patients did not
answer to the question regarding the sport activity so we considered those patients as not practicing
any sport.
The mean time between the injury and the surgical treatment was 10 months (min 2
months, max 144 months); however in the 52.6% of the cases the surgery was
performed in 3 months from the injury.
Regarding the subjective judgment, the results of the evaluation forms filled out are the following:
.. The VAS scale used to look at the type and intensity of the pain was filled out from all the
patients studied. The mean value was 0.5.72% of the patients crossed the value 0 (no pain).
20% (5 cases) from 0.5 and 3 (slight pain); while 2 patients (8%) gave respectively 4.5 and
5.5 (moderate pain).
.. The analysis of the KOOS form, showed the following results: symptoms 89.3, pain 95.5, daily
activity 91.9 and sport activity 85.8.
.. In the IKDC form the average result was 84.3%. The knee was considered normal or quite
normal in the 96% of the cases. Only in one case the result was bad in terms of pain and
function of the operated knee.
The clinical evaluation done by Prof. R. Lorentzon, showed results extremely interesting: there was no
swelling in 92% of the cases (23 subjects), and slight pain in 8% (2 subjects). The range of motion of
the operated knee compared to the contra lateral was full in 92%; in 4% slightly reduced, in particular
was recorded a deficit of 15° of knee flexion angle. Only one case complained giving way of the
operated knee. The muscular trophism at the level of the thigh was normal or slightly normal lcm and 50.00 mm2 . The average of the results of the elliptic area on the operated
side was 223.0936 mm2 and 264.1836 mm2 on the other side.
The isokinetic evaluation with Kin-Com of the pick of strength in concentric of the flexor and extensor
muscles on the operated side compared to the control side, showed in over 60% better results on the
operated side. In particular the extensor strength resulted better in 64% (16 cases), while only in the
36% resulted higher in the control side, with differences of strength between 0-10% in 6 cases (24%),
between 10-25% in 3 cases (12%), while in no case we hade differences over 25%. Also for the flexor
muscles no significant difference has been found; the strength was over 25% side to side. Better
results have been found on the operated side in 68% (17 cases), values less than 10% in 6 cases
(25%) and between 10-25% in 2 cases (8%). It has been calculated the relationship between extensor
and flexor of the same side for each side; on the operated side the relationship was normal (6%-80%)
in 6 cases (24%); a decreasing of 40-59% in 18 cases (72%), while the difference was important
(>80%) in 1 case (4%). The same relationship on the control side was normal in 4%; a difference
ranged from 40% to 59% in 92 % of the cases and in only 1 case the difference of strength was over
80%.
Conclusion: Based on the results of our study with a five years follow-up and on the data of the
International Literature, we can say that the new generation of Lars® artificial ligament used as graft
in the ACL reconstruction is an" happy reality", although actually the choice of the patients are
selective. The five years follow-up, in our opinion is a sufficient period to judge the results, as "
scientifically" valid. We did not experience the bad complications of the 80's; no one of the patients
had significant swelling of the knee as signs of chronic post-op synovitis, and the objective and
subjective results were positive in over 95%. However the positive evaluation from the neutral
examiner observer is another positive result on the final evaluation. From the 25 cases tested, only
one of them had bad results, based on the clinical and instrumental evaluation, which showed
residual knee instability. It is important to point it out the results in using the biological graft as
autograft or allograft are the same or even worse. We think that based on structural and mechanic
characteristics of the artificial ligament, to be considered as JAB (Intra Articular Brace), they have to
be implanted on subjects over 40 yrs old, symptomatic and with the need of a faster recovery time.
The other indications are to be considered as an exception to evaluate case by case. The typical
example is a top level athlete that practices a sport activity that put his ACL at higher risk of lesion,
and that a faster recovery time is needed for an important chance of his life such as world
championship or Olympics game. In those cases the use of the synthetic ligament to reconstruct the
ACL is justified in patients less than 40 yrs old. We have to look at the data coming out from the
literature and do not have fear in using the new generation of synthetic ligaments. Considering that
the autograft and allograft actually are not the best solution and waiting for new solutions in ACL
reconstruction, the synthetic graft can be for sure one of the choices.
We can assure the patients that this new synthetic graft will never be responsible of synovitis and will
provide knee stability. It has been demonstrated in laboratory study that this ligament has a wear
resistance of 22 million of cycles, that corresponds about at 10 years of straining using. The graft is
biocompatible and in the next future it will be bioactive. We are collaborating with other research
groups to make a new bioactive ligament, where the fibers of polyethylene terephthalate (PET) and
bioactive groups attached on the synthetic ligament can link the growth factors; the adhesive proteins
and the type I collagen as well as the fibroblasts. This research project is in progress; the laboratory
studies are already done and we are testing this new graft on animals. The preliminary histological
data are brilliant and promising for the future. The synthetic graft combines very well with the all
inside technique, an innovative less invasive technique, based on the respect of the tissue with a valid
fixation system. If the technique is well performed and the patient selection is well done we can
assure the patients on the final results, which are show positive in 95% of the cases. The post-op
rehabilitation program it is not so heavy and in about 40 days the patient can start working and
returning to sport without any problem. As demonstrated, the majority of the patients treated are
satisfied of the results obtained.
Acknowledgments: The authors thank Ronny Lorentzon MD, PhD (Umea, Sweden); Fabio Vercillo
MD (Perugia, Italy); E. Canonico (Perugia, Italy) and A. Archilletti (Perugia, Italy) for assistance in
data collection and processing.
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