Differences in graft orientation using the transtibial and anteromedial portal technique in anterior cruciate ligament reconstruction: A magnetic resonance imaging study

Abstract

The purpose of this study was to evaluate differences in graft orientation between transtibial (TT) and anteromedial (AM)
portal technique using magnetic resonance imaging (MRI) in anterior cruciate ligament (ACL) reconstruction. Fifty-six patients
who were undergoing ACL reconstruction underwent MRI of their healthy and reconstructed knee. Thirty patients had ACL reconstruction
using the TT (group A), while in the remaining 26 the AM (group B) was used. In the femoral part graft orientation was evaluated
in the coronal plane using the femoral graft angle (FGA). The FGA was defined as the angle between the axis of the femoral
tunnel and the joint line. In the tibial part graft orientation was evaluated in the sagittal plane using the tibial graft
angle (TGA). The TGA was defined as the angle between the axis of the tibial tunnel and a line perpendicular to the long axis
of the tibia. The ACL angle of the normal knee in the sagittal view was also calculated. The mean FGA for group A was 72°,
while for the group B was 53° and this was statistically significant (P<0.001). The mean TGA for group A was 64°, while for the group B was 63° (P=0.256). The mean intact ACL angle for group A was 52°, while for the group B was 51°. The difference between TGA and intact
ACL angle was statistically significant (P<0.001) for both groups. Using the AM portal technique, the ACL graft is placed in a more oblique direction in comparison
with the TT technique in the femoral part. However, there are no differences between the two techniques in graft orientation
in the tibial part. Normal sagittal obliquity is not restored with both techniques.

Full text

KNEE
Differences in graft orientation using the transtibial
and anteromedial portal technique in anterior cruciate ligament
reconstruction: a magnetic resonance imaging study
Michael Elias Hantes ÆVasilios C. Zachos Æ
Athanasios Liantsis ÆAaron Venouziou Æ
Apostolos H. Karantanas ÆKonstantinos N. Malizos
Received: 19 October 2008 / Accepted: 23 January 2009 / Published online: 24 February 2009
ÓSpringer-Verlag 2009
Abstract The purpose of this study was to evaluate dif-
ferences in graft orientation between transtibial (TT) and
anteromedial (AM) portal technique using magnetic reso-
nance imaging (MRI) in anterior cruciate ligament (ACL)
reconstruction. Fifty-six patients who were undergoing
ACL reconstruction underwent MRI of their healthy and
reconstructed knee. Thirty patients had ACL reconstruction
using the TT (group A), while in the remaining 26 the AM
(group B) was used. In the femoral part graft orientation
was evaluated in the coronal plane using the femoral graft
angle (FGA). The FGA was defined as the angle between
the axis of the femoral tunnel and the joint line. In the tibial
part graft orientation was evaluated in the sagittal plane
using the tibial graft angle (TGA). The TGA was defined as
the angle between the axis of the tibial tunnel and a line
perpendicular to the long axis of the tibia. The ACL angle
of the normal knee in the sagittal view was also calculated.
The mean FGA for group A was 72°, while for the group B
was 53°and this was statistically significant (P\0.001).
The mean TGA for group A was 64°, while for the group B
was 63°(P=0.256). The mean intact ACL angle for
group A was 52°, while for the group B was 51°. The
difference between TGA and intact ACL angle was sta-
tistically significant (P\0.001) for both groups. Using the
AM portal technique, the ACL graft is placed in a more
oblique direction in comparison with the TT technique in
the femoral part. However, there are no differences
between the two techniques in graft orientation in the tibial
part. Normal sagittal obliquity is not restored with both
techniques.
Keywords Anterior cruciate ligament reconstruction 
Transtibial technique Anteromedial portal technique 
Magnetic resonance imaging
Introduction
According to many anatomical studies, femoral attachment
of the anterior cruciate ligament (ACL) lies deep and low
on the medial wall of the lateral femoral condyle [2,6,23].
Correct position of the femoral tunnel is a critical point for
a successful single bundle ACL reconstruction. In the
sagittal plane the femoral tunnel must be in the posterior
quadrant of the Blumensaat line [5,19]. The importance of
correct position in the sagittal plane in ACL reconstruction
recognized many years ago and incorrect position of the
femoral tunnel yields poor clinical results [8,14,15].
However, the importance of correct position of an ACL
graft in the coronal plane has been underestimated. In the
last years, many authors demonstrated the biomechanical
advantages of recreation of the obliquity of the ACL graft
(like the native ACL) in the coronal plane [13,18,21,22].
In addition, it has been shown that a vertically oriented
graft in the coronal plane is associated with poor clinical
results resulting in a persistent pivot shift [16].
Paper presented at the 6th Biennial ISAKOS Congress, Florence,
ITALY, 2007 and 12th ESSKA 2000 Congress, Innsbruck, Austria
2006.
M. E. Hantes (&)V. C. Zachos A. Liantsis 
A. Venouziou K. N. Malizos
Department of Orthopaedic Surgery, Medical School,
University Hospital of Larissa, University of Thessalia,
Mezourlo, 41110 Larissa, Greece
e-mail: hantesmi@otenet.gr
A. H. Karantanas
Department of Radiology, University Hospital,
University of Crete, Heraklion, Greece
123
Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886
DOI 10.1007/s00167-009-0738-8

The most popular technique for femoral tunnel creation
in ACL reconstruction is the transtibial (TT) technique
[10]. Using this technique the femoral tunnel is drilled
through the tibial tunnel and therefore, position of the
femoral tunnel is dictated by the tibial tunnel. According to
many surgeons correct placement of the femoral tunnel can
be achieved using the transtibial technique [13,22].
However, as it has been demonstrated by Arnold et al. [3]
transtibial femoral tunnel drilling does not reach the ana-
tomical site of the ACL insertion at 10 o’clock. Usually
with this technique, a position corresponding between 11
and 12 o’clock position could be reached and the graft is
placed in a relatively vertical position. In order to over-
come these problems many authors recommend the antero-
medial (AM) portal technique [9,11]. Using this technique,
the femoral tunnel is drilled through the AM portal while
the knee is placed in maximum flexion between 125°and
130°. In this way, the surgeon has more freedom to place
the graft in the anatomical position (deep and low in the
notch) at 10 or even 9.30 o’clock. Therefore, an oblique (or
more horizontal) placement of the graft is achieved close to
the course of the native ACL.
The primary goal of this retrospective comparative study
was to evaluate graft orientation after ACL reconstruction,
using the TT and AM technique for femoral tunnel creation
by the same surgeon. The magnetic resonance image (MRI)
was chosen as the most accurate imaging modality to
evaluate graft position and orientation in both the sagittal
and coronal plane. Our hypothesis was that the AM tech-
nique would provide a more oblique placement of the graft
which is more close to the anatomy of the ACL in com-
parison to the TT technique, in this single surgeon’s series.
A secondary aim was to investigate graft orientation in the
sagittal plane and to compare the reconstructed with the
normal knee.
Materials and methods
Fifty-six patients who underwent arthroscopic ACL
reconstruction by a single surgeon with a four-strand band
hamstring (HS) tendon autograft and identical type of fix-
ation (for both the femoral and tibial part) were
retrospectively enrolled in this study. All patients were
operated in our institution from January 2002 to May 2004.
Patients who underwent other major operations in the
affected knee were excluded from the study. Finally,
patient’s agreement to have a postoperative MRI of their
operated knee and an intact ACL of their contralateral knee
were necessary for inclusion in the study.
Two distinct patient groups were defined. Patients
operated between January 2002 and March 2003 underwent
ACL reconstruction using the TT technique. This group
consisted of 30 patients. In the second group which con-
sisted of 26 patients, ACL reconstruction was performed
through the AM portal. This group of patients operated
between March 2003 and May 2004. From March 2003, the
senior surgeon changed his technique form TT to AM.
Surgical technique
Both the semitendinosus and gracilis tendons were used for
ACL reconstruction. Graft harvesting was performed
through a 2.5-cm longitudinal incision using a tendon
striper. A standard anterolateral portal is used for diag-
nostic arthroscopy and an anteromedial portal as a working
portal. The ACL stump is debrided using arthroscopic
scissors and a full radius shaver. A curette is used to per-
form a notchplasty and to debride the notch.
The tibial tunnel is then created. With the knee at 90°of
flexion, the endoscopic aimer is inserted to the knee
through the anteromedial portal and is adjusted to 50°. The
entry point of the tibial tunnel was placed between the
anterior part of the medial collateral ligament and the tibial
tubercle. The ACL stump, the PCL and the inner rim of the
anterior horn of the lateral meniscus are used as landmarks
to identify the optimal position. A guide pin is then drilled
into the joint and a cannulated reamer equal to the graft
diameter is used to create the tibial tunnel. The technique
was identical for both (TT and AM) groups.
In the TT group, the femoral tunnel was drilled through
the tibial tunnel. To do this a femoral guide with an
appropriate offset (e.g., with an 8-mm graft a femoral guide
with a 5-mm offset is used) is introduced into the joint
through the tibial tunnel and it was placed in the posterior
aspect of the notch. Flexion of the knee was approximately
70–90°. Then a K-wire was placed in a position which has
been determined by the femoral guide (usually at approx-
imately the 11 o’clock position for the right knee or at
approximately the 1 o’clock position for the left knee). The
K-wire was then over-drilled with a reamer corresponding
to the size of the graft diameter and to a depth of 30 mm.
Graft fixation was performed with 2 RigidFix pins (DePuy
Mitek, Raynham, MA) in the femoral tunnel. The Rigidfix
guide frame was inserted into the femoral tunnel through
the tibial tunnel. Tibial fixation was performed with the
Intrafix system (DePuy Mitek, Raynham, MA).
In the AM group the femoral tunnel was drilled through
the anteromedial portal. The knee was placed in maximum
flexion between 125°and 130°. Again, a femoral guide
with an appropriate offset is introduced into the joint
through the anteromedial portal. With the aim of the
femoral guide a K-wire is then placed into the center of the
anatomic insertion of the ACL (usually at approximately
the 10 o’clock position for the right knee or at approxi-
mately the 2 o’clock position for the left knee). With the
Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886 881
123

knee in full flexion the K-wire is over-drilled with a reamer
corresponding to the size of the graft diameter and to a
depth of 30 mm. Graft fixation was performed with 2
RigidFix pins (DePuy Mitek, Raynham, MA) in the fem-
oral tunnel. However, the Rigidfix guide frame was
inserted into the femoral tunnel through the anteromedial
portal in this group of patients. Similarly, tibial fixation
was performed with the Intrafix system (DePuy Mitek,
Raynham, MA).
MRI protocol and measurements
All patients included in this study, underwent an MRI
examination on both the operated and the non-operated
knee at least 1 year after ACL reconstruction. Both legs
were positioned in the gantry. The examined knee was
placed in the coil in full extension and 10–15°of external
rotation with a supporting device to assure comfort and
immobilization. MRI was performed with a 1.0-T MR
imager (Philips Intera; Philips Medical Systems, Best, The
Netherlands) by using a quadrature coil. The MRI protocol
included one pulse sequence (T1-w Spin Echo) in sagittal,
coronal, and transverse planes and the parameters were as
follows: 550/15 (TR ms/TE ms), matrix of 304 9512,
field of view 16 914 cm, four signal excitations, 4-mm
slice thickness for the coronal and sagittal acquisitions and
500/20 (TR msec/TE msec), matrix of 304 9512, field of
view 16 cm 914 cm, three signal excitations, 3-mm slice
thickness for the transverse acquisition. No fat suppression
was applied to avoid susceptibility artifacts from the pre-
vious operation (ACL reconstruction). The main imaging
protocol included the sagittal and coronal planes. For the
operated leg, an image in the coronal plane that showed the
femoral tunnel in almost its entire length was used. Also, in
the sagittal plane an image that showed the tibial tunnel in
almost its entire length was used. For the non-operated leg
an image in the sagittal plane that showed the intact ACL
was used.
Orientation of the ACL graft was calculated in
the coronal plane using the femoral graft angle (FGA); the
FGA was defined as the angle between the axis of the
femoral tunnel and the joint line (Fig. 1). In the sagittal
plane, graft orientation was calculated using the tibial graft
angle (TGA); the TGA was defined as the angle between
the axis of the tibial tunnel and a line perpendicular to the
long axis of the tibia (Fig. 2). In the non-operated leg, the
angle of the intact ACL was calculated by two lines: a line
perpendicular to the long axis of the tibia and a line along
the intact ACL. One senior musculoskeletal radiologist and
one orthopedic surgeon blinded to the procedure performed
all the measurements.
Fig. 1 The femoral graft angle (FGA) is shown on this coronal MRI
image. A line parallel to the axis of the femoral tunnel and the joint
line were used to calculate the FGA. In this case the FGA is 57°(ACL
reconstruction with AM portal technique)
Fig. 2 The tibial graft angle (TGA) is shown on this sagittal MRI
image. A line parallel to the axis of the tibial tunnel and a line
perpendicular to the long axis of the tibia were used to calculate the
TGA. In this case the TGA is 64°(ACL reconstruction with TT
technique)
882 Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886
123

Statistics
The independent samples ttest was used for comparison
between the groups. The data were analyzed with the
SPSS statistical package (SPSS ver.12, Chicago, Illinois).
To determine interobserver variability, interclass correla-
tion coefficient was calculated. Significance was set at
P\0.05.
Results
There were 28 males and 2 females with a mean age of
25.6 years in the TT group and 26 males and 4 females
with a mean age of 27.2 years in the AM group. The mean
time for the MRI study was18.4 months (range 15–26) for
the TT group and 22.6 months (range 17–28) for the AM
group.
The mean FGA for the TT group was 71°(76°–66°)
while for the AM group it was 52°(46°–59°). This dif-
ference was statistically significant (P\0.001) (Fig. 3).
The mean TGA for group was 64°(57°–67°), while for the
AM group it was 63°(57°–66°) but this was not statisti-
cally significant (Fig. 4). The mean angle of the intact ACL
angle for the TT group A was 52°(45°–54°), while for the
AM group was 51°(46°–56°) (Fig. 5). The difference
between TGA and intact ACL angle was statistically sig-
nificant (P\0.001) for both groups.
The interobserver variability regarding MRI measure-
ments were excellent with intraclass correlation coefficients
of 0.91, 0.95 and 0.94 for the FGA, TGA and intact ACL
angle, respectively.
Discussion
In this study, two different techniques for femoral tunnel
creation in ACL reconstruction were evaluated. Our study
demonstrated that the AM technique results in a signifi-
cantly more oblique femoral tunnel in the coronal plane in
comparison to the TT technique. The femoral tunnel was
approximately 20°more vertical in the TT group in com-
parison to the AM group and this was statistically
significant. According to biomechanical studies an oblique
femoral tunnel placement in the coronal plane improves
rotatory knee stability in comparison to a more vertical
position [18,21]. Probably the biomechanical and clinical
advantages of the obliquity of the graft in the coronal plane
are due to its anatomic placement, low in the notch in the
anatomical footprint of the native ACL. This position
usually corresponds to the so-called 10 o’clock position.
Placement of the graft high in the notch results in a more
vertical graft. This position usually corresponds to the
so-called 11 or even 11.30 o’clock position. In our study,
graft obliquity was not determined by the o’clock
description because this system lacks precision and is
dependent on subjective interpretation to some extent.
Measurement of graft obliquity was performed in our study
by using the MRI images and consistent landmarks (axis of
the tunnel and a vertical line to the joint line). This method
Fig. 3 Comparison of graft obliquity in the coronal plane between
(a) a reconstructed knee with the TT technique (FGA is 73°) and (b)a
reconstructed knee with the AM portal technique (FGA is 48°)
Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886 883
123

is objective and accurate, since interobserver variability
was excellent according to our results.
Loh et al. [18] as well as Scopp et al. [21] demonstrated
in cadaver biomechanical models that reconstructing the
femoral tunnel at the oblique anatomic origin of the ACL,
rotational stability of the knee is more effectively restored.
Clinically, a vertically oriented graft is related to residual
pivot shift although anterior tibial translation can be
restored. Lee et al. [17] reported that in a subset of patients
with a vertical graft orientation, clinical results (pivot shift,
KT-1000 measurements) and Lysholm score was signifi-
cantly worse in comparison to patients with a more oblique
graft placement. Similarly, Jepsen et al. [14] found that a
change in the femoral tunnel placement from 1 o’clock
position to 2 o’clock position (more oblique graft) results
in a significant difference in the scores on the IKDC
evaluation form. Therefore, a better clinical result could be
expected in patients with an oblique orientated graft.
Unfortunately, we cannot correlate our MRI findings with
the clinical results at that time since the two groups of our
patients are under clinical evaluation and the clinical
results will be reported in the near future.
According to our results, the TT technique is less ideal
in comparison to AM technique to create an oblique fem-
oral tunnel in the coronal plane. Arnold et al. [3]ina
cadaver study found that using the TT technique (through a
correctly placed tibial tunnel) the graft is placed in a non-
anatomical position higher in the notch in most of the
cases. Similarly, in other cadaver studies it was found that
using the AM portal technique the center of the femoral
tunnel is significantly closer to the center of the femoral
ACL footprint in comparison to the TT technique [7,16].
However, other surgeons report that an oblique femoral
tunnel can be obtained with the TT technique [19]. Sim-
mons et al. [13] reported that it is possible for the surgeon
to place the femoral tunnel at 60°in the coronal plane with
the transtibial technique if he/she controls the angle of the
tibial tunnel. To achieve this one has to create the entry
point of the tibial tunnel at the junction of the superior
border of the pes anserine tendons and anterior border of
Fig. 4 Comparison of graft obliquity in the sagittal plane between (a)
a reconstructed knee with the TT technique (TGA is 67°) and (b)a
reconstructed knee with the AM portal technique (FGA is 62°)
Fig. 5 The intact ACL angle (from a normal knee) is shown on this
sagittal MRI image. In this case the ACL angle is 46°
884 Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886
123

the medial collateral ligament. In this way a more oblique
tibial tunnel is created and it is easier to reach the anatomic
origin of the ACL [20]. In our study, the entry point of the
tibial tunnel was placed between the anterior part of the
medial collateral ligament and the tibial tubercle and
probably this fact affected our results. However, limitations
still exist with the TT even by modifying the entry point of
the tibial tunnel. As is has been shown by Heming et al.
[12] it is possible to achieve a proper position of the ACL
graft using the TT technique, but the tibial tunnel must start
close to the joint line (only 14 mm inferior to the joint
line).
Ahn et al. [1] using the TT technique and hamstring
autograft for their ACL reconstruction found a mean
coronal graft angle of 17°in their MRI study which is
similar to our results with the TT group. However, com-
parison to our AM group is not possible because they did
not use the AM technique in their study. In another MRI
study, Lee at el. [18] reported similar results with a mean
coronal graft of 16.5°and good clinical results. Interest-
ingly, in the same study, patients with a more vertical graft
(mean coronal angle of 10.5°) had worse results.
In the sagittal plane, neither technique was effective to
restore normal ACL obliquity. According to our results,
graft obliquity in reconstructed patients with the TT and
AM was similar and significantly more vertical in com-
parison to the native ACL. Our results, are in accordance
with other studies (using similar MRI protocols) which
reported graft obliquity in reconstructed patients between
63°and 70°[1,4,17]. In our opinion, this problem is
created because the surgeon chooses to place the tibial
tunnel slightly posterior to the anatomic ACL insertion in
order to avoid roof impingement. Another explanation
might be that many surgeons prefer to drill their tibial
tunnel in a more vertical way because they think that a
tunnel of sufficient length is achieved in this way. How-
ever, a more oblique tunnel in the sagittal plane can
produce also a sufficient length of the tibial tunnel as it has
been shown by many authors [13,22]. This means that the
surgeon is not able to reproduce the orientation of the
native ACL in the sagittal plane using the techniques which
are available today. Although it has been reported that
anterior–posterior knee displacement is restored, we
believe that a vertical graft in the sagittal plane may
influence graft function and there is room for improvement
regarding our surgical technique.
There are some limitations of this study. First of all its
retrospective nature had less scientific significance. There
was no randomization and no clinical correlation. However,
our study has the advantages of a consecutive series of
patients, operated by the same surgeon using the same graft
and fixation technique. In addition, MRI was chosen as the
most accurate imaging modality to evaluate graft position
and orientation in both the sagittal and coronal plane.
Conclusion
Our results showed that in our hands, the AM portal tech-
nique in ACL reconstruction results in a significantly more
oblique femoral tunnel in the coronal plane in comparison to
the TT technique. This is because drilling the femoral tunnel
independent of the tibial tunnel the surgeon has more free-
dom to place the graft in an anatomical (more oblique)
position close to the native ACL. However, graft obliquity in
the sagittal plane could not be restored with either technique
and the graft was significantly more vertical than the normal
ACL. The clinical results will be reported in the future in a
long-term follow-up study to determine if there is any clin-
ical implication of these findings.
References
1. Ahn JH, Lee SK, Yoo JC, Ha HC (2007) Measurement of the
graft angles for the anterior cruciate ligament reconstruction with
transtibial technique using postoperative magnetic resonance
imaging in comparative study. Knee Surg Sports Traumatol
Arthrosc 15:1293–1300
2. Arnoczky SP (1983) Anatomy of the anterior cruciate ligament.
Clin Orthop Relat Res 172:19–25
3. Arnold MP, Kooloos J, van Kampen A (2001) Single incision
technique misses the anatomical femoral anterior cruciate liga-
ment insertion: a cadaver study. Knee Surg Sports Traumatol
Arthrosc 9:194–199
4. Ayerza MA, Muscolo DL, Costa-Paz M, Makino A, Rondon L
(2003) Comparison of sagittal obliquity of the reconstructed
anterior cruciate ligament using magnetic resonance imaging.
Arthroscopy 19:257–261
5. Bernard M, Hertel P, Hornung H, Cierpinski T (1997) Femoral
insertion of the anterior cruciate ligament. Radiological quadrant
method. Am J Knee Surg 10:14–21
6. Colombet P, Robinson J, Christel P et al (2006) Morphology of
anterior cruciate ligament attachments for anatomic reconstruc-
tion: a cadaveric dissection and radiographic study. Arthroscopy
22:984–992
7. Gavriilidis I, Motsis EK, Pakos EE, Georgoulis AD, Mitsionis G,
Xenakis TA (2008) Transtibial versus anteromedial portal of the
femoral tunnel in anterior cruciate ligament reconstruction: a
cadaveric study. Knee 15:364–367
8. Getelman MH, Friedman MJ (1999) Revision anterior cruciate
ligament reconstruction surgery. J Am Acad Orthop Surg 7:189–
198
9. Hantes ME, Dailiana Z, Zachos VC, Varitmidis SE (2006)
Anterior cruciate ligament reconstruction using the Bio-TransFix
femoral device and anteromedial portal technique. Knee Surg
Sports Traumatol Arthrosc 14:497–501
10. Harner CD, Fu F, Irrgang JJ, Vogrin TM (2001) Anterior and
posterior cruciate ligament reconstruction in the new millennium:
a global perspective. Knee Surg Sports Traumatol Arthrosc
9:330–336
Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886 885
123

11. Harner CD, Honkamp NJ, Ranawat AS (2008) Anteromedial
portal technique for creating the anterior cruciate ligament fem-
oral tunnel. Arthroscopy 24:113–115
12. Heming J, Rand J, Steiner M (2007) Anatomical limitations of
transtibial drilling in anterior cruciate ligament reconstruction.
Am J Sports Med 35:1708–1715
13. Howell SM, Gittins ME, Gottlieb JE, Traina SM, Zoellner TM
(2001) The relationship between the angle of the tibial tunnel in
the coronal plane and loss of flexion and anterior laxity after
anterior cruciate ligament reconstruction. Am J Sports Med
29:567–574
14. Jespen CF, Lundberg-Jensen AK, Faunoe P (2007) Does the
position of the femoral tunnel affect the laxity or clinical outcome
of the anterior cruciate ligament reconstructed knee? A clinical
prospective randomized, double-blind study. Arthroscopy
23:1326–1333
15. Johnson DL, Swenson TM, Irrgang JJ, Fu FH, Harner CD (1996)
Revision anterior cruciate ligament surgery: experience from
Pittsburgh. Clin Orthop Relat Res 325:100–109
16. Kaseta MK, DeFrate LE, Charnock BL, Sullivan RT, Garrett WE
Jr (2008) Reconstruction technique affects femoral tunnel
placement in anterior cruciate ligament reconstruction. Clin
Orthop Rel Res 466:1467–1474
17. Lee MC, Seong SC, Lee S, Chang CB, Park YK, Jo H, Kim CH
(2007) Vertical femoral tunnel placement results in rotational
knee laxity after anterior cruciate ligament reconstruction.
Arthroscopy 23:771–778
18. Loh JC, Fukuda Y, Tsuda E, Steadman RJ, Fu FH, Woo SL
(2003) Knee stability and graft function following anterior cru-
ciate ligament reconstruction: comparison between 11 o’clock
and 10 o’clock femoral tunnel placement. Arthroscopy 19:297–
304
19. Pinczewski LA, Salmon LJ, Jackson WF, von Bormann RB,
Haslam PG, Tashiro S (2008) Radiological landmarks for
placement of the tunnels in single-bundle reconstruction of the
anterior cruciate ligament. J Bone Joint Surg Br 90:172–179
20. Raffo SC, Pizzarello P, Richmond JC, Pathare N (2008) A
reproducible landmark for the tibial tunnel origin in anterior
cruciate ligament reconstruction: avoiding a vertical graft in the
coronal plane. Arthroscopy 24:843–845
21. Scopp JM, Jasper LE, Belkoff SM, Moorman CTIII (2004) The
effect of oblique femoral tunnel placement on rotational con-
straint of the knee reconstructed using patellar tendon autografts.
Arthroscopy 20:294–299
22. Simmons R, Howell SM, Hull ML (2003) Effect of the angle of
the femoral and tibial tunnels in the coronal plane and incre-
mental excision of the posterior cruciate ligament on tension of
an anterior cruciate ligament graft: an in vitro study. J Bone Joint
Surg Am 85:1018–1029
23. Takahashi M, Doi M, Abe M, Suzuki D, Nagano A (2006)
Anatomical study of the femoral and tibial insertions of the
anteromedial and posterolateral bundles of human anterior cru-
ciate ligament. Am J Sports Med 34:787–792
886 Knee Surg Sports Traumatol Arthrosc (2009) 17:880–886
123