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TUNNEL POSITIONING IN REMNANT SPARING DOUBLE BUNDLE ACL RECONSTRUCTION — A 2-YEAR STUDY OF MRI TUNNEL POSITIONS, CLINICAL OUTCOMES AND TUNNEL CONFLUENCE

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  • Orthopaedics wa, perth
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TUNNEL POSITIONING IN REMNANT SPARING DOUBLE BUNDLE ACL RECONSTRUCTION — A 2-YEAR STUDY OF MRI TUNNEL POSITIONS, CLINICAL OUTCOMES AND TUNNEL CONFLUENCE

Abstract and Figures

Purpose: The purpose of this study is to examine the outcomes of a cohort of patients who have undergone a new surgical technique for anterior cruciate ligament (ACL) tunnel targeting using the footprint of the torn ACL as soft tissue markers. This is in the setting of anatomical ACLR with remnant preservation. Methods: This retrospective single center cohort study was conducted on patients undergoing a primary ACLR between August 2008 and February 2013. A total of 103 patients underwent ACLR with a remnant sparing technique with non-radiological soft tissue targeting of femoral and tibial tunnels. Exclusion criteria included skeletal immaturity, concomitant meniscal repair or ligament surgery, knee malalignment, delayed presentation ((Formula presented.)6 months post injury) and incomplete medical insurance. At 2 years all patients had gadolinium MRI scan, plain film X-ray, and a clinical assessment including KT-1000 arthrometry, and the following outcome scores; Tegner, IKDC (subjective/objective), Lysholm, Cincinnati and ACL Quality of Life. Results: A total of 44 patients (18 males, 26 females; mean age 30.9 years (Formula presented.)/(Formula presented.)11.8) were enrolled within the study. About 93.2% of the participants achieved an IKDC objective rating of A or B. The mean scores for outcome measures were; IKDC Subjective (84.9(Formula presented.)(Formula presented.)/(Formula presented.)(Formula presented.)11), Tegner (6.1(Formula presented.)(Formula presented.)/(Formula presented.)(Formula presented.)2), Lysholm (87.2(Formula presented.)(Formula presented.)/(Formula presented.)(Formula presented.)11.3), Cincinnati (358.1(Formula presented.)(Formula presented.)/(Formula presented.)(Formula presented.)40.8) and ACL Quality of Life (75.4(Formula presented.)(Formula presented.)/(Formula presented.)(Formula presented.)19). There were no graft failures at follow up. No patients had a loss of full extension (Formula presented.). All tunnels were positioned satisfactorily. Almost half of all femoral tunnels (47.8%) and 30.4% of tibial tunnels were confluent at the joint surface. Conclusions: This series demonstrates that anatomical double tunnel ACLR using non-radiological guided remnant retention technique, provides satisfactory 2-year clinical outcomes and is a safe and effective option. Targeting tunnels to be within the native remnant leads to high rates of tunnel confluence.
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TUNNEL POSITIONING IN REMNANT SPARING DOUBLE
BUNDLE ACL RECONSTRUCTION |A 2-YEAR STUDY OF
MRI TUNNEL POSITIONS, CLINICAL OUTCOMES AND
TUNNEL CONFLUENCE
Travis M. Falconer
Perth Orthopaedic & Sports Medicine Center
31 Outram Street, West Perth, Western Australia 6005
travis.falconer@perthortho.com.au
Satyen Gohil
Orthopaedics WA, Suite 15 Wexford Medical Centre
3 Barry Marshall Parade, Murdoch WA 6150, Australia
Louise Tusak
Perth Orthopaedic & Sports Medicine Center
31 Outram Street, West Perth, Western Australia 6005
William H. Breidahl
Perth Radiological Clinic, 127 Hamersley Rd,
Subiaco WA 6008, Australia
Peter T. Annear
Perth Orthopaedic & Sports Medicine Center
31 Outram Street, West Perth, Western Australia 6005
Received 7 December 2015
Revised 26 June 2016
Accepted 27 June 2016
Published 25 August 2016
Correspondence to: Travis M. Falconer, Perth Orthopaedic & Sports Medicine Center, 31 Outram Street, West Perth, Western
Australia 6005.
Journal of Musculoskeletal Research, Vol. 19, No. 1 (2016) 1650004 (15 pages)
© World Scientic Publishing Company
DOI: 10.1142/S0218957716500044
1650004-1
ABSTRACT
Purpose: The purpose of this study is to examine the outcomes of a cohort of patients who have
undergone a new surgical technique for anterior cruciate ligament (ACL) tunnel targeting using the
footprint of the torn ACL as soft tissue markers. This is in the setting of anatomical ACLR with remnant
preservation. Methods: This retrospective single center cohort study was conducted on patients un-
dergoing a primary ACLR between August 2008 and February 2013. A total of 103 patients underwent
ACLR with a remnant sparing technique with non-radiological soft tissue targeting of femoral and
tibial tunnels. Exclusion criteria included skeletal immaturity, concomitant meniscal repair or ligament
surgery, knee malalignment, delayed presentation (>6 months post injury) and incomplete medical
insurance. At 2 years all patients had gadolinium MRI scan, plain lm X-ray, and a clinical assessment
including KT-1000 arthrometry, and the following outcome scores; Tegner, IKDC (subjective/objec-
tive), Lysholm, Cincinnati and ACL Quality of Life. Results: A total of 44 patients (18 males, 26 females;
mean age 30.9 years þ/11.8) were enrolled within the study. About 93.2% of the participants
achieved an IKDC objective rating of A or B. The mean scores for outcome measures were; IKDC
Subjective (84.9 þ/11), Tegner (6.1 þ/2), Lysholm (87.2 þ/11.3), Cincinnati (358.1 þ/40.8) and
ACL Quality of Life (75.4 þ/19). There were no graft failures at follow up. No patients had a loss of
full extension >5. All tunnels were positioned satisfactorily. Almost half of all femoral tunnels (47.8%)
and 30.4% of tibial tunnels were conuent at the joint surface. Conclusions: This series demonstrates
that anatomical double tunnel ACLR using non-radiological guided remnant retention technique,
provides satisfactory 2-year clinical outcomes and is a safe and effective option. Targeting tunnels to be
within the native remnant leads to high rates of tunnel conuence.
Keywords: Anterior cruciate ligament; Remnant sparing; Double bundle; Tibial tunnel; Femoral
tunnel; ACLR.
INTRODUCTION
Injury to the anterior cruciate ligament (ACL) has
potentially devastating immediate and long-term
consequences and occurs relatively frequently
with a one-year incidence of around 35 per
100,000 people.
12
The focus of the orthopedic
surgeon and the general public over the past 30
years on this injury has made for a quickly
evolving topic. Debate still remains over whether
using a double bundle anatomical technique and
retaining remnants of the torn ligament offer the
patient better outcomes, given the technical
challenge of the technique and the risk of
tunnel malposition and early graft failure or
impingement.
Since ODonghue
19
rst identied the ACL to
be the main contributor to anterior knee stability,
there have been many advances in the anatomical
and biomechanical understanding, surgical tech-
nique and a trend toward replicating the normal
or anatomical kinematics with reconstructions.
A double bundle anatomical reconstruction is
more technically demanding
22
than its single
bundle counterpart. While biomechanical studies
support this concept,
23,26
clinical trials are yet to
display a signicant benet to the patient. As
such there still remains a state of clinical equi-
poise regarding whether recreating the two
functional bundles of the ACL is advantageous
to the patients and their long-term recovery.
Similarly, the remnant material from the torn
native ACL has been identied to contain many
components, such as vasculature, mechan-
oreceptors and free neural ends,
7,9,11,12
that could
be advantageous in graft healing, ligamentization
and potentially early return to activity. The
combination of double bundle anterior cruciate
ligament reconstruction (ACLR) and retaining
this remnant could also be additionally chal-
lenging and may compromise tunnel position,
T. M. Falconer et al.
1650004-2
overcrowd the notch area, cause tunnel conu-
ence and ultimately affect outcomes if not per-
formed correctly. Only one previous case study
reports this combination technique using intrao-
perative uoroscopy and arthroscopic remnant
splitting to conrm tunnel positions
31
and avoid
such complications. Splitting the remnant may
lessen biological and proprioceptive function.
Avoiding remnant repair and intraoperative
uoroscopy may reduce operative time. We have
recently developed a technique of performing
four tunnel double bundle ACLR with remnant
sparing, without splitting the remnant or using
uoroscopy intra-operatively.
This study examines a cohort of patients that
have undergone a double tunnel anatomical re-
construction with ACL remnant preservation.
This technique uses the footprint of the torn ACL
and its remnant as soft tissue markers for tunnel
placement. The purpose of this study is to
examine the outcomes of this cohort of patients
who have undergone a new surgical technique
for ACL tunnel targeting using the footprint of
the torn ACL as soft tissue markers. We hy-
pothesize that using this technique tibial tunnel
positions will be comparable to the outcomes of
similar studies using bony anatomy or radiolog-
ically guided techniques. We also hope to dem-
onstrate comparable two-year clinical outcomes
with this technique, and satisfactory outcomes in
those patients who have MRI evidence of tunnel
conuence.
MATERIALS AND METHODS
This retrospective single center cohort study was
conducted with institutional ethics committee
approval on patients undergoing a primary an-
terior cruciate ligament reconstruction between
August 2008 and February 2013. A total of 103
double bundle remnant sparing ACL recon-
structions were performed during this period.
They were contacted to take part in a clinical re-
view focusing upon ligamentous stability, a
gadolinium MRI scan and plain lm radiographs.
Patients were only included if they consented
to gadolinium MRI scans at 1 and 2 years post-
operatively and a clinical review. Exclusion cri-
teria included skeletal immaturity, concomitant
meniscal repair or ligament surgery, knee mala-
lignment, delayed presentation (>6 months post
injury) and incomplete medical insurance. Those
who did not consent or were excluded were
compared for age and sex to the patients included
in the study.
Surgical Technique
An arthroscopy assisted anatomical double bun-
dle reconstruction technique was performed with
the patient supine, with a high tourniquet and the
leg free from a brace in a side bolster. A diag-
nostic arthroscopy was performed and meniscal
and chondral surgery completed. Semitendinosis
and gracilis tendons were harvested using a
23 cm transverse incision 1 cm proximal to the
pes ancerinus insertion. Each tendon was strip-
ped of muscle and doubled over itself onto a
20 mm closed loop Endobutton (Smith and
Nephew), the tails whipped-stitched together
with 1 vicryl. The grafts were pre-tensioned after
diameter measurement.
In preparing the intercondylar notch only un-
stable tibial remnant tissue was removed from
the ACL stump. This was performed at 90and
30of knee exion, the latter position to identify
anteriorly subluxed tissue. The ligamentum
mucosum and obstructing fat pad tissue was
resected. A 2 2 cm square window was cleared
of soft tissue off the posterior lateral wall of the
notch in the 1:30 oclock position (left knee) with
the knee at 90exion (Fig. 1).
The position of the anteromedial bundle (AMB)
was marked with an awl 5 mm from the posterior
Tunnel Positioning in Remnant Sparing ACLR
1650004-3
wall, in the 1:30 oclock position with respect to
the proximal (deep) notch clockface and with re-
spect to the existing footprint. The position of the
posterolateral bundle (PLB) was then marked
with an awl using the AMB position as a reference.
It was marked using a blunt probe 8 mm along a
line drawn from the AMB position, 30inferiorly
to the long axis of the femur. This point is ap-
proximately 5 mm from the medial and posterior
edges of the lateral femoral condyles articular
cartilage margin and within the PLB footprint.
An accessory central and inferior medial portal
(Fig. 2) was created and with the knee hyperexed
femoral tunnel drilling through this portal to
avoid remnant damage and creates satisfactory
tunnel lengths (>35 mm). A blunt trochar through
the medial portal is used to protect the remnant
during drilling if needed. Tunnels were prepared
for 20 mm closed loop Endobutton xation. In-
complete visualization during femoral tunnel
preparation neccessated switching the arthro-
scope to a medial viewing portal. Prepared tun-
nels are shown in Fig. 3.
The tibial tunnels were prepared using the
ACL director drill guide, elbow aimer and bullet
guide (Smith and Nephew Pty. Ltd, product
codes 72205517, 72205518 and 72205525) with the
knee in 90exion. For the AMB the jig was set to
65with the tibial entry just medial to the tibial
tuberosity 3 cm below the joint line. The tip of the
jig was then placed centrally in the tibial stump
8 mm posterior to the anterior margin of the ACL
stump (Fig. 4). The guide wire was advanced to
blisterbut did not penetrate the stump. For the
PLB tunnel, the elbow jig was set at 45the tibial
entry alongside the MCL, 2 cm below the joint
line (Fig. 5). For this tunnel the jig elbow is placed
to abut the posterolateral margin of the ACL
tibial insertion. The tip of this guidewire is
Fig. 1 Shaved medial wall of lateral femoral condyle. Fig. 2 Retained remnant and placement of accessory port.
Fig. 3 Prepared and drilled femoral tunnels.
T. M. Falconer et al.
1650004-4
advanced until visualized exiting the remnant
posterolaterally. The targeting technique for the
tibial tunnels aims for both tunnels to remain
within the remnant and remnant footprint
avoiding graft-notch impingement.
The PLB tunnel is prepared rst with size ap-
propriate reamers. The AMB tunnel is rst
reamed carefully to complete the bony tunnel
only but not advancing within the remnant. A
4.2 mm full radius resecter shaver canalizes the
remnant, through the tibial tunnel (Fig. 6),
advancing in line within the remnant by varus/
valgus and knee exion angle adjustment. The
grafts are passed in sequence with the PLB pas-
sed rst. Figures 7and 8show the grafts in the
nal exed and extended positions, respectively.
The knee was cycled 15 times with graft under
maximal manual tension. The AMB was xed at
45of exion Intrax screw (DePuySynthes Pty.
Ltd.) and the PLB was xed at 20of exion
Milagro Advance screw (DePuySynthes Pty. Ltd.).
Fig. 4 Elbow targeting job for the tibial AMB.
Fig. 5 Elbow jig abuts PL corner of tibial ACL remnant.
Fig. 6 Shaver through remnant to ensure safe graft passage.
Fig. 7 The remnant, AMB and PLB (left to right).
Tunnel Positioning in Remnant Sparing ACLR
1650004-5
Post-operative Rehabilitation
All patients were placed in a resting extension
splint for two weeks allowing crutch weight
bearing as tolerated. Inpatient exercises focused
on regaining knee range of motion, patella mo-
bility and swelling reduction. Patients were
allowed to cease the use of the brace once their
knee effusion had resolved. They were com-
menced on closed chain exercises, hydrotherapy
and stationary cycling at six weeks. At four
months post-operatively they commenced jog-
ging, progressing to change of direction exercise
and sport specic exercises by six months. They
were then commenced on full sport and pivoting
activities at 912 months post-operatively.
Clinical Assessment
All patients had a minimum of 2 years follow up
(23.9 years). Their clinical assessment was per-
formed by a single experienced physiotherapist.
Range of motion was measured using a goni-
ometer with loss of extension dened as an in-
ability to achieve full extension (0). Lachmans,
Pivot Shift and Anterior drawer tests were per-
formed in conjunction with KT-1000 instru-
mented arthrometry (MEDmetric, San Diego,
CA). Questionnaires included the International
Knee Documentation Committee (IKDC) Subjec-
tive and Objective score, Tegner Activity Score,
Cincinnati Knee Rating System, Lysholm Knee
Scale, ACL Quality of Life Score (ACL QOL). The
time taken to return to sport and every day life
activities was also recorded.
Radiological Follow-up
All patients were assessed using a gadolinium
magnetic resonance imaging (MRI) at 1 and 2
years post-operatively and plain lm radio-
graphs. All MRI scans were performed on a 1.5 T
MRI (Signa Excite, GEMedical Systems, Milwau-
kee, Wis) using a dedicated 8 channel knee coil.
Imaging was conned to 2 mm thick slices with a
0.5 mm gap between each slice and coronal, axial
and sagittal sequences were performed. Oblique
axial T1w (TR ¼640 ms, TE ¼16 ms) fat sup-
pressed sequences were obtained through the
graft pre and post IV gadolinium. MRI was used
to assess the signal intensity of the ACL grafts,
tunnel positions, graft impingement, cyclops
lesions, progressive tunnel widening and tunnel
conuence.
Signal noise quotient (SNQ) was used as a
measure of graft vascularity as previously de-
scribed by Weiler et al. in 2001.
30
This patient
cohort had gadolinium-enhanced MRI scans be-
cause they were also part of a larger co-existent
case-control study examining graft vascularity
and healing.
Tibial tunnel positions were assessed using the
sagittal slice best showing the tibial insertions
with reference to Amis & Jacobs line as previ-
ously described by Columbet et al.
5
Femoral
tunnels were assessed using plain lm lateral
X-ray combined with the sagittal slice of the
femur best showing the femoral insertions. This
method was adapted from the Radiographic
Fig. 8 Final graft position.
T. M. Falconer et al.
1650004-6
Quadrant Method as described by Bernard et al.
4
SNQ was used an assessment of the grafts vas-
cularity as previously described.
13
In this study,
we have measured the SNQ of the AMB, the PLB
and the PCL, pre and post contrast at 1 and 2
years post-operatively.
Tunnel widening was dened as interval
change in tunnel diameters across the 1 and 2
year MRI scans as measured on the sagittal MRI
scan 1 cm below the chondral surface. Tunnel
conuence was dened as overlap of the tunnels
at the joint surface interface resulting in no bony
bridge between them. Cyclops lesions and their
sizes were also noted.
14
A single experienced
musculoskeletal specialized radiologist reported
all MRI scans.
RESULTS
Demographics and Operating Time
A total of 44 patients were enrolled into this
study and received the remnant preserving
ACLR technique with soft tissue targeting. The
mean age of the participants was 30.9 years
(þ/11.8) and there were 18 males and 26
females reviewed. A total of 20 of the recon-
structions were of the left knee and 24 of the right
knee. The mean operating time, as recorded by
video arthroscopy was 45 min (þ/12). Of the 59
patients who were not included in the study, 32
were male and 21 were female with an average
age of 28.1 years (þ/10.6).
Knee Range of Motion and Laxity
There were no patients with a recorded loss of
full extension greater than 5. A total of
12 (27.3%) patients had loss of full extension
(05). All patients regained exion to within 5
of the contralateral side. The mean side-to-side
anterior laxity difference of the group measured
by the KT-1000 arthrometer was 0.7 mm
(þ/1.2), with 97.7% of all patients having a
negative Pivot Shift Test. The clinical results are
summarized in Table 1.
Nine out of 44 patients (20.4%) had a graft
with a negative side-to-side arthrometer reading.
Three out of these nine had a loss of full exten-
sion, one patient with 4and the other two with
a loss of 5. Their mean scores compared to the
whole cohort are displayed in Table 2. None of
these patients were symptomatic, complained of
impingement type symptoms or required surgery
to improve knee extension.
Clinical Outcome Measures
Overall satisfactory outcomes were achieved
with 93.2% of the participants achieving a rating
of A or B on their IKDC Objective rating. The
mean scores for the the IKDC Subjective Score
(84.9), Tegner Activity Scale (6.1), Lysholm Knee
Score (87.2), Cincinnati Knee Score (358.1) and the
ACL Quality of Life Score (75.4) are summarized
in Table 1.
Tunnel Positions and Tunnel Conuence
Tibial tunnels were satisfactorily positioned
(AMB ¼39.1 þ/5.4; PLB ¼54.3 þ/6.1) ac-
cording to the method described by Columbet
et al.
5
(normal values being 36% for the AMB and
52% for the PLB along Amis & Jacobs Line). The
femoral tunnels were also satisfactorily posi-
tioned according to a modied Radiographic
Quadrant Method.
14
The normal heights and
depths within the quadrant were dened as 75%
and 75% for the AMB and 66% and 50% for the
PLB, respectively. These results are summarized
in Table 1and Figs. 9and 10 demonstrate these
methods as well as illustrating the normal ana-
tomical positions and the mean positions
achieved in our study.
Tunnel Positioning in Remnant Sparing ACLR
1650004-7
Almost half of all femoral tunnels (47.8%) and
30.4% of tibial tunnels were conuent at the joint
surface and 8 patients had conuence of both on
both femur and tibia. The mean distance between
the tunnels and their size are displayed in Table 1.
MRI Findings
The SNQ at 2 years for the AMB (2.6 þ/1.1)
PLB (3.0 þ/1.3) and PLB (1.9 þ/0.4) and their
trends over the two-year period are summarized
in Fig. 11. They demonstrate that while the SNQ
for both the AMB and the PLB is decreasing with
time it does not demonstrate the same low SNQ
as the native PCL. The AMB has higher SNQ at
both the 1 and 2-year follow up. There was no
evidence of progressive tunnel widening or sy-
novitis on MRI. There were 2 MRI Cyclops
lesions identied at the 1-year scan and only one
of these remained present at the 2-year scan.
Table 1 Summary of Clinical and Radiological Outcomes.
Clinical Measures Data (n=44)
Anterior laxity KT1000 (mean þ/SD) (mm) 0.7 þ/1.2
Pivot Shift Test (%)
ve 97.7
þve 2.3
Extension loss (>5) (%) 0
Mean operating time (video recording) (min) 45 þ/12
Outcome scores Data (n¼44)
IKDC Objective Score (%) A 52; B 41; C 4.5; D 2.3;
IKDC Subjective Score (mean þ/SD) 84.9 þ/11.0
Tegner 6.1 þ/2.0
Lysholm 87.2 þ/11.3
Cincinnati 358.1 þ/40.8
ACL Quality of Life 75.4 þ/19.0
Radiographic results Data (n¼23)
Tunnel Positions (See Figs. 9and 10)
Tibia (% of AP distance according to Amis & JacobsLine*ref)
AMB 39.1, PLB 54.3
Femur (% according to Radiographic Quadrant Method*ref)
Tunnel Sizes (mm) AMB Height 74.0, Depth 70.4
PLB Height 59.2, Depth 49.8
Tibia AMB 9.0
PLB 7.2
Femur AMB 7.3
PLB 6.6
Mean distance between center of tunnels (mm) Tibia 8.0
Femur 7.9
Conuence (%) Tibia 30.4
Femur 47.8
Both tunnels 17.8
Evidence of synovitis Nil
Evidence of progressive tunnel widening Nil
T. M. Falconer et al.
1650004-8
Complications
There were no graft ruptures in our cohort and all
grafts were intact on MRI scanning. One patient
had some mild symptoms of instability with a
positive pivot shift and a KT-1000 difference of
5 mm. Two patients returned to theater. One was
for a meniscal tear 12 months after their recon-
struction. The other patient had symptoms of
graft impingement and required an arthroscopic
notchplasty 4 months post-ACL reconstruction.
At the 2-year follow up, she had normal range of
motion compared to her contralateral side. One
(a) (b)
Fig. 9 (Color online) Tibial tunnel positions. (a)- position of anteromedial (AMB) bundle. Blue represents the anatomical
position and yellow the mean of the study group. (b)- position of posterolateral (PLB) bundle. Blue represents the anatomical
position and green the mean of the study group.
Table 2 Summary of Mean Patient Outcomes in those Patients with Tight Grafts
(negative KT 1000 SSD) Compared to those with Normal Grafts (positive KT 1000 SSD).
Clinical Measures Tight Grafts (n=9) Cohort (n=35)
Anterior laxity KT1000 (mean þ/SD) (mm) 0.73 0.9 þ/1.2
Pivot Shift Test (%)
ve 100 97.7
þve 0 2.3
Extension loss (>5) (%) 3/9 (33%) 0
Outcome Scores Tight Grafts (n¼9) Cohort (n¼35)
IKDC Objective Score (n) A 5; B 3; A 18; B 15;
C0;D1; C2;D0;
IKDC Subjective Score (mean) 87.3 84.4
Tegner 6.7 5.9
Lysholm 92.9 81.4
Cincinnati 365.6 356.2
ACL Quality of Life 74.2 75.7
Tunnel Positioning in Remnant Sparing ACLR
1650004-9
patient was found to have a cyclops lesion on his
2-year MRI scan. This was not symptomatic and
not associated with any loss of extension or graft
impingement.
DISCUSSION
Recent meta-analysis reports anatomic double
bundle ACLR results in greater knee stability, less
graft failures and less re-operation rates when
compared with single bundle ACLR.
8,10,28,29
Sec-
ondly, a remnant sparing ACLR technique may
offer easier tunnel positioning, improved graft
biology and better post-operative knee proprio-
ception.
7,9,11,21
While the authors acknowledge
the clinical advantages of a combined anatomic
double bundle remnant sparing ACLR technique
are not yet dened, this is the rst paper report-
ing the minimum 2-year results while introduc-
ing and validating a new tunnel positioning
approach using the intact remnant and not direct
vision or intraoperative image intensier. This
study conrms satisfactory tunnel positions
(Table 1) when compared to anatomical mod-
els.
4,5
The clinical results were comparable with
Signal Noise Quotient
0
1.9
3.8
Time
1 year 2 years
AMB PLB PCL
Fig. 11 Trends for SNQ for the AMB, PLB and PCL over
time.
(a) (b)
Fig. 10 (Color online) Femoral tunnel positions. (a)- position of anteromedial (AMB) bundle. Blue represents the anatomical
position and yellow the mean of the study group. (b)- position of posterolateral (PLB) bundle. Blue represents the anatomical
position and green the mean of the study group.
T. M. Falconer et al.
1650004-10
remnant and non-remnant sparing anatomic
double bundle ACLR (Table 2). We also demon-
strated that when using the remnant, footprint
and bony anatomy for tunnel placement, it is
highly likely that tunnels are conuent at the joint
surface interface. We have also seen similar SNQ
and comparative graft vascularity to other pre-
viously published data where remnant tissue is
kept.
13,25
The main aim of this study was to validate
graft tunnel placement guided solely by the intact
ACL remnant and not by using remnant spitting
with direct vision or radiological guidance
(Table 1). While tibial tunnels are solely remnant
guided, we recognize that our technique for
femoral tunnel positioning makes use of both the
remnant and notch anatomy, and therefore is not
a new technique. The use of the Radiographic
Quadrant Method to measure our femoral tun-
nels again conrmed satisfactory positions with
this technique.
There have been various techniques described
for retaining the ACL stump, mostly in the set-
ting of single bundle reconstructions.
1,2,1618,20
These have all involved detaching the proximal
ACL stump to gain visualization of the femoral
tunnels. Because we are using the intact remnant
margins and not the tibial footprint or the bony
notch anatomy to guide tunnel positions we are
able to leave as much of the remnant intact as
possible. This allows maximal preservation of
free neural endings, vasculature and mechan-
oreceptors to take advantage of their theoretical
benets.
There are a few key points in our surgical
technique that allow maximal preservation of the
ACL stump. Firstly when passing our guide wire
for the AMB, the guide pin blisters but does not
penetrate the tissue. Secondly when the reamer is
passed over the guide wire care is taken to just
breach the bone and not the remnant. The shaver
is then used to complete the tunnel and allow
adequate passage of the graft without disrupting
the remnant. In the technique most similar to
ours, Yasuda et al.
31
describes splitting the rem-
nant to assess guide wire placement and gently
passing the reamer over the guide wire in to the
joint, both of which could further damage the
remnant. In the article by Kim et al.
15
they de-
scribe changing the direction of the reamer to
anti-clockwise before entering the joint and
passing the entire graft through the tibial tunnel
to minimize this damage.
Secondly, we use an accessory inferior medial
portal for targeting and reaming the femoral
tunnels. This is a more central portal allowing a
different view into the notch wall which allows
access for the reamer past the remaining remnant
without damaging it. In contrast Yasuda et al.
31
uses a trans-tibial technique which may com-
promise femoral tunnel positioning.
27
Our results reassure us that with this tech-
nique we can forgo the use of intra-operative
uoroscopy and still adequately position the
tunnels. This also has the added benetof
shortened tourniquet time (45 þ/12 versus 101
þ/19 min) when compared to Yasudas tech-
nique.
31
We presume that this difference in
tourniquet time is because time is taken to use the
uoroscopy and readjust the guide wire, coupled
with the fact that we use independent drilling of
femoral and tibial tunnels, compared to the more
technically demanding trans-tibial femoral dril-
ling described by Yasuda.
There has been some debate in the literature
about the ideal tibial tunnel position ACLR. Bedi
et al.
3
has investigated the outcomes of non-ana-
tomic versus anatomic positioning of the tibial
graft. These authors recommended placement of
the graft within the central portion of the native
remnant stump, which is in keeping with the
benets of our described surgical technique.
We acknowledge that we have analyzed our
post-operative tibial tunnel positions using a
Tunnel Positioning in Remnant Sparing ACLR
1650004-11
cadaveric model
5
which may be a limitation
within our study, however we feel these results
show that our positions are satisfactory.
The effect of combining anatomical recon-
struction and remnant sparing techniques are less
known. Yasuda et al.
31
and Kim et al.
15
described
the only other study to date that has used double
tunnel remnant retention technique. Yasuda and
colleagues also found tight grafts on KT-1000
testing with a mean KT-1000 side to side differ-
ence of 0.7 mm, which was equivalent to our
ndings. Kim et al. however demonstrated laxity
measures more in keeping with studies using a
non-remnant sparing double tunnel technique
with a KT-2000 mean of 1.65 mm. It is unclear
why the laxity of the grafts in both Yasudas
study and ours is signicantly smaller that other
studies in the literature using a non-remnant
sparing technique. Table 3, taken from Yasudas
article
31
highlight the fact that tight grafts may be
a result of this surgical technique, particularly the
remnant sparing aspect. It has not however been
established if the remnant sparing technique is
associated with tighter grafts.
1,13
Yasuda reported 98% of all patients in their
study to have IKDC Objective ratings of A or B.
We also found that over 93% of our patients
achieved this rating. Yasuda also reported no
graft failures at their follow up in keeping with
our ndings. These low rates of failure and sat-
isfactory knee scores seen in our study and that
by Yasuda et al.,
31
could be related to increased
vascularity and biological healing.
Our study had 9 patients (20%) with grafts that
were tighter than their contralateral normal knee.
While 3 of these had loss of extension, none re-
quired notchplasty or arthrobrosis surgery. The
two-year outcome scores of these nine patients
were satisfactory and were slightly higher in their
mean compared to the grafts with positive KT
100 SSD, as demonstrated in Table 2, however
numbers are too small to draw signicant con-
clusions. The combination of remnant sparing
double bundle ACLR may lead to over-constraint
of the knee. The position of graft tensioning may
contribute to this problem. We have since moved
to tensioning both grafts in 20of exion. In-
creased joint contact pressures from over-con-
straint in ACLR may lead to early chondral
change and early osteoarthritis, which is a con-
cern in this subset of patients.
Just as there have been many different surgical
techniques for remnant sparing described, there
are also a myriad of classications for the
remaining stump of the ACL. This remnant has
been classied according to scarring to the sur-
rounding structures
6
as well as the percentage
of the native ACL remaining intact.
2,13
We did
Table 3 Comparisons of Anterior Laxity Measurements in Recently Published Studies with Hamstrings Grafts.
(Adapted from Yasuda et al.
31
)
Authors No. of Patients Mean Side-to-Side Anterior Laxity (mm) Pivot-Shift Test (Negative/Total) (%)
Yasuda et al. (2006) 72 1.1 87.5
Aglietti et al. (2007) 75 1.4 84.0
Muneta et al. (2007) 68 1.4 85.3
Kondo et al. (2008) 328 1.2 81.3
Jarvela et al. (2008) 77 1.3 81.8
Siebold et al. (2008) 49 1.0 97.1
Streich et al. (2008) 49 1.1 95.8
Aglietti et al. (2010) 70 1.2 85.0
Yasuda et al. (2012) 44 0.7 81.8
Falconer et al. (2015) 45 0.7 97.8
T. M. Falconer et al.
1650004-12
not classify the remnant in this study, however all
surgeries were within six months of the injury.
This was in keeping with Ahn
2
and colleagues
ndings that there was better incorporation of
the graft if early surgery was performed, before
any mechanoreceptor deterioration is able to
occur.
7
We did not expect to see such high rates of
tunnel conuence in our study. The theoretical
concerns regarding tunnel conuence include
poor graft-bone ingrowth, progressive osteolysis
and tunnel widening, less biomechanical stabili-
ty, higher failure rates and difculty in the revi-
sion setting. We saw MRI conuence rates of
30.4% on the tibia, 47.8% on the femur and 17.8%
on both, which is higher than that previously
reported in the literature (1923%).
24
We did not
however see any progressive tunnel widening
between the 1-year and 2-year MRI scans. There
were no signicant differences in graft laxity or
any of the clinical outcomes when we compared
patients with any tunnel conuence to those
without, although the numbers are too small to
meaningfully compare. We suggest that many of
the perceived problems with tunnel conuence
may in fact just be theoretical. A larger series may
benet further understanding of this issue.
It has previously been described that there is a
high incidence of MRI cyclops lesions with a
remnant sparing single bundle technique.
13,14
The
incidence of MRI cyclops lesions in this study
was low at both the 1-year (8.7%) and 2-year
(4.3%) follow-ups. We propose that because we
used a different technique during notch prepa-
ration these lesions were avoided. By debriding
the notch in the 30position unstable remnant
tissue subluxed anteriorly under the fat pad can
be identied and material that could contribute
to a cyclops lesion is removed. We think that
this method has resulted in a lower number of
cyclops lesions in this cohort.
Short of performing histological examinations
from biopsies at second look arthroscopies, it is
very difcult to accurately assess the vascularity
of the graft. The correlation with gadolinium en-
hanced MRI signals was rst described in the
sheep model by Weiler et al.
30
In the paper by
Gohil et al.,
13
MRI SNQ was used to compare graft
vascularity between remnant retention and stan-
dard debridement techniques. In their prospective
randomized study, they found that SNQ was
signicantly better in the remnant retention tech-
nique at two months. It is not possible to compare
our results to those taken by Gohil as the absolute
values of SNQ are a fraction and dependent on the
individual MRI machine being used and the as-
sociated signals. The trends of a negative linear
correlation reported appear to reect the results
that we found in our study. Our results also
demonstrated a higher SNQ in the PLB compared
to the AMB as previously reported.
25
This difference may provide a mechanism for
double bundle failures. Further research in this
eld is required to make any correlations with
early graft vascularization, ligamentization,
healing and potentially an early return to activity.
Our study had a number of limitations. We had
a relatively small sample size and no control
group for comparisons. Although the patient co-
hort were acute ACL reconstructions (<6 months)
the remnant spared was not classied. The use of
the Radiographic Quadrant Method using a
combined image from the MRI and plain lm
X-ray has not been validated and will need further
investigation.
CONCLUSION
This case series demonstrates that anatomical
double tunnel anterior cruciate ligament recon-
struction using medial portal drilling and non-
radiological guided remnant retention technique,
Tunnel Positioning in Remnant Sparing ACLR
1650004-13
provides satisfactory tunnel positions, two-year
clinical outcomes and is a safe and effective op-
tion. Targeting tunnels to be within the native
remnant leads to high rates of tunnel conuence,
although the clinical signicance of this is
uncertain.
The tibial tunnel placement in this technique
was guided solely by the intact tibial ACL rem-
nant. Satisfactory tibial tunnels were maintained
using this technique and reinforcing that radio-
logical guidance or splitting or debriding of the
ACL stump were not required. We recognize that
our technique for femoral tunnel positioning
makes use of both the remnant and notch anat-
omy and is not totally remnant guided, and
therefore not a new technique. The use of the
Radiographic Quadrant Method to measure our
femoral tunnels again conrmed satisfactory
positions with this technique.
We represent that this submission is original
work and is not under consideration for publi-
cation with any other journal.
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Tunnel Positioning in Remnant Sparing ACLR
1650004-15
... Arthroscopic-assisted, double-tunnel ACLR was performed as previously described by Falconer et al [22,23]. The patients in the CONTROL group had the knee cycled 15 times with the graft under maximal manual tension. ...
Article
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The paper compares hamstring autograft with a "hybrid" graft of hamstrings and a small LARS ligament in ACL reconstruction patients. The paper concludes ACLR utilizing a hybrid autologous/LARS® construct facilitated accelerated rehabilitation without evidence of increased failure or early graft stretch. Additionally, there was no clinical difference in functional outcome scores between the HYBRID and CONTROL groups. Although not statistically significant, the HYBRID group had an unacceptably high re-operation rate at 2-years post ACLR, and is therefore not recommended as a surgical technique by the primary author. The refinement of ACLR to facilitate patients’ safe and early return to previous levels of function presents a topic for future research.
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Article
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Article
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Article
The anterior cruciate ligament has a complex fiber anatomy and is not considered to be a uniform structure. Current anterior cruciate ligament reconstructions succeed in stabilizing the knee, but they neither fully restore normal knee kinematics nor reproduce normal ligament, function. To improve the outcome of the reconstruction, it may be necessary to reproduce the complex function of the intact anterior cruciate ligament in the replacement graft. We examined the in situ forces in nine human anterior cruciate ligaments as well as the force distribution between the anteromedial and posterolateral bundles of the ligament in response to applied anterioi tibial loads ranging from 22 to 110 N at knee flexion angles of 0–90°. The analysis was performed using a robotic manipulator in conjunction with a universal force-moment sensor. The in situ forces were determined with no device attached to the ligament, while the knee was permitted to move freely in response to the applied loads. We found that the in situ forces in the anterior cruciate ligament ranged from 12.8 ± 7.3 N under 22 N of anterior tibial load applied at 90° of knee flexion to 110.6 ± 14.8 N under 110 N of applied load at 15° of flexion. The magnitude of the in situ force in the posterolateral bundle was larger than that in the anteromedial bundle at knee flexion angles between 0 and 45°, reaching a maximum of 75.2 ± 18.3 N at 15° of knee flexion under an anterior tibial load of 110 N. The magnitude of the in situ force in the posterolateral bundle was significantly affected by knee flexion angle and anterior tibial load in a fashion remarkably similar to that seen in the anterior cruciate ligament. The magnitude of the in situ force in the anteromedial bundle, in contrast, remained relatively constant, not changing with flexion angle. Significant differences in the direction of the in situ force between the anteromedial bundle and the posterolateral bundle were found only at flexion angles of 0 and 60° and only under applied anterior tibial loads greater than 66 N. We have demonstrated the nonuniformity of the anterior cruciate ligament under unconstrained anterior tibial loads. Our data further suggest that in order for the anterior cruciate ligament replacement graft to reproduce the in situ forces of the normal anterior cruciate ligament, reconstruction techniques should take into account the role of the posterolateral bundle in addition to that of the anteromedial bundle.
Article
During an arthroscopic examination for an anterior cruciate ligament (ACL) reconstruction, there is a relatively thick remnant ACL tibial stump attached to the posterior cruciate ligament (PCL) or rarely remained between the femur origin and the tibia insertion. We thought that preservation of the remnant ACL original bundle might promote graft healing or be helpful in preserving the proprioception and function to stabilize the knee. Therefore, we established a remnant preservation procedure without additional instruments during an ACL reconstruction using a bio-cross pin (RIGIDfix system®: Mitek, Johnson & Johnson, USA) for the femoral tunnel fixation. The remnant ACL was sutured (usually three stitches) using a suture hook (Linvatec, Largo, FL), and both ends of the sutures were pulled to the far anteromedial (AM) portal. These sutures protected the remnant tissue during the ACL reconstruction because medial traction of these sutures can provide a wide view during the reconstruction. After the femoral and tibial tunnel formation, these sutures were pulled out to the inferior sleeve of the cross pin using a previously inserted wire loop via an inferior sleeve. After graft passage, a superior cross pin was first fixed and tibial fixation was then performed. Finally, inferior cross pin fixation was performed and ties were made at the entrance of the inferior cross pin.
Article
To determine whether double-bundle anterior cruciate ligament reconstruction leads to better restoration of anterior and rotational laxity and range of motion than single-bundle reconstruction. A search was performed in the Medline, Embase, CINAHL, and Cochrane databases. All randomized, quasi-randomized, and observational clinical trials that reported the outcome of double- versus single-bundle anterior cruciate ligament reconstruction were included in our meta-analysis. The primary outcomes were anterior laxity (KT arthrometer; MEDmetric, San Diego, CA), pivot shift, and range of motion. Subgroup analyses were performed for more than 2 years' follow-up, anatomic reconstruction, and nonanatomic reconstruction. The quality of the included studies was scored by use of the GRADE Checklist. Included 12 studies in this meta-analysis, 5 of which were randomized. There was a statistically significant difference in favor of double-bundle reconstruction for anterior laxity (KT arthrometer difference, -0.6 mm), Lachman test (64% risk reduction of positive Lachman), and pivot-shift test (69% risk reduction of positive shift). Similar results were found for the subgroup with more than 2 years' follow-up and anatomic reconstructions. There were no significant differences for the subgroup with nonanatomic reconstructions, except a 2.6 times risk increase of extension deficit with nonanatomic double-bundle reconstruction compared with nonanatomic single-bundle reconstruction. Most of the included studies were found to have at least one serious limitation in study design. In comparison with single-bundle reconstruction, double-bundle reconstruction showed less anterior laxity, as measured by the KT arthrometer and Lachman test, and better rotational laxity, as measured by the pivot-shift test. The majority of the included studies had at least one major limitation in study design that decreased the quality of the study. Level I, meta-analysis.