Download The Anatomy of the Medial Patellofemoral Ligament

n Review Article
The Anatomy of the Medial Patellofemoral
Ligament
Thai Q. Trinh, MD; Jason R. Ferrel, MD; Jared C. Bentley, MD; Robert N. Steensen, MD
abstract
Recurrent patellar dislocation is observed in many patients treated nonoperatively following primary dislocation. Injury to the medial patellofemoral
ligament (MPFL) is reported in the majority of patients following dislocation.
There is an increased interest in repair or reconstruction of the MPFL for patients experiencing recurrent instability. The femoral attachment of the MPFL
is critical in determining graft behavior following reconstruction. The femoral
attachment can be determined by referencing local anatomy, fluoroscopic
imaging or on the basis of desired graft-length changes. This article reviews
the anatomy of the MPFL, with a focus on its femoral insertion site as it pertains to anatomic, isometric, and anisometric reconstruction. [Orthopedics.
201x; xx(x):xx-xx.]
R
ecurrent lateral patellar dislocation is noted to occur in approximately 44% to 71% of patients
treated nonoperatively following primary
dislocation.1-5 The medial patellofemoral
ligament (MPFL) is the primary soft tissue restraint to lateral translation of the
patella and is considered the “essential
lesion” of patellar dislocation.6,7 Previous
studies have reported injury to the MPFL
in 95% to 100% of patients following
acute dislocation.8-10 This has led to an
interest in repair or reconstruction of the
MPFL for patients experiencing recurrent
patellar dislocation. Although numerous
reconstruction techniques have been reported, the femoral attachment site of the
reconstructed graft is critical in determining graft behavior throughout range of
motion. The purpose of this article is to
review the literature reporting the femoral
attachment site of the MPFL and to analyze the effect of this site on graft behavior during reconstruction.10-15
Anatomy
Understanding of the femoral insertion
point of the MPFL continues to evolve.
Previous studies of the femoral insertion
point have described varying relationships
with the medial epicondyle, adductor tubercle, medial collateral ligament (MCL),
posteromedial capsule, and adductor magnus tendon.6,9,11,14-19 In general, the MPFL
spans from the area containing the medial
femoral epicondyle to the superior onethird or one-half of the medial border of
the patella.20 Feller et al16 dissected 20
MONTH/MONTH 201x | Volume xx • Number X
cadaveric knees and described the MPFL
attaching to the femur along the anterior
aspect of the medial epicondyle. In contrast, Tuxøe et al9 described the femoral
origin arising distal to the adductor magnus tendon along the anterior aspect of the
adductor tubercle in 39 cadaveric knees.
Superficial fibers of the MPFL were noted
to arise from the posteromedial capsule
in 100% of knees, while a portion of the
distal fibers joined the MCL in 82% of
knees.9
Smirk and Morris21 evaluated 25 cadaveric knees and noted the femoral attachment of the MPFL was most commonly observed along the posterior aspect
of the medial epicondyle (84%), approximately 1 cm distal to the adductor tubercle. Forty-four percent of knees possessed
an isolated MPFL attachment site. The
remaining knees possessed a wider atThe authors are from the Department of Orthopaedics (TQT, JRF, RNS), Mount Carmel Medical Center, Columbus, Ohio; and The Steadman
Hawkins Clinic of the Carolinas (JCB), Greenville, South Carolina.
The authors have no relevant financial relationships to disclose.
Correspondence should be addressed to:
Thai Q. Trinh, MD, Department of Orthopaedics,
Mount Carmel Medical Center, 793 W State St,
Columbus, OH 43222 (Thai.Trinh.12@gmail.
com).
Received: May 8, 2016; Accepted: August 23,
2016.
doi: 10.3928/01477447-20170223-03
1
n Review Article
tachment site including an area posterior
to the adductor magnus tendon (20%), the
adductor magnus tendon itself (12%), the
adductor tubercle (4%), or a combination
of all three (4%). The remaining 4 knees
(16%) had an attachment anterior to the
medial epicondyle. In contrast, Steensen
et al19 noted the femoral attachment as the
entire length of the anterior aspect of the
medial epicondyle, with the inferior portion of the MPFL and the superior portion
of the MCL in direct contact in 100% of
knees.
Nomura et al14 recognized some controversy by identifying the MPFL femoral
attachment superoposterior to the medial
epicondyle just distal to the adductor tubercle in 20 knees. Superficial fibers extended to the posteromedial capsule, while
the deep fibers inserted directly onto bone
in all knees. Variable insertions onto the
superficial MCL were also identified in
50% of knees.14 Contrary to the study by
Smirk and Morris,21 the MPFL was not
observed to insert onto the adductor magnus tendon.14 LaPrade et al18 (8 knees) and
Philippot et al15 (23 knees) both described
the femoral attachment proximal and posterior to the medial epicondyle between the
adductor magnus tendon and the superficial MCL. Philippot et al15 also reported
a strong relationship between the MPFL
and MCL in 40% of knees, similar to the
findings reported by Steensen et al19 and
Nomura et al.14 No specimens possessed
insertions onto either the posteromedial
capsule or the adductor magnus tendon.15
Fujino et al10 documented the femoral insertion of the MPFL 10 mm distal to the
adductor tubercle along the long axis of
the femur in 31 cadaveric knees using a
combination of gross pathology and 3-dimensional computed tomography reconstructions. The insertion area of the MPFL
occupied approximately 56.5±169 mm2 in
that study.10
Two studies17,20 described the MPFL
as the confluence of 2 independent bundles. Baldwin20 evaluated 50 cadaveric
knees and described 2 independent femo-
2
ral origins. One was a transverse origin
from a bony groove between the medial
epicondyle and the adductor tubercle. The
other was an oblique decussation from
the leading edge of the superficial MCL.
Kang et al,17 however, described “functional bundles” with a common origin
distal to the adductor magnus tendon and
proximal to the MCL attachment. These
bundles, termed the inferior straight and
short oblique bundles, inserted onto the
superior and middle portions of the patella, respectively.17
On the basis of these studies, there appears to be some variability in the femoral attachment site of the MPFL (Table).
Although authors generally agree that the
femoral attachment site can be found near
the medial epicondyle (Figure 1), variability exists in the insertion area as well
as the ligament’s relationship with the
adductor tubercle, MCL, posteromedial
capsule, and adductor magnus tendon. It
is unknown how these relationships affect
the function of the MPFL in both normal
knees and those of patients with recurrent
patellar instability.
mal to a perpendicular line that intersects
the posterior aspect of Blumensaat’s line)
may more closely replicate the anatomy
of the native MPFL.
Wijdicks et al24 found the attachment
8.9 mm distal and anterior from the adductor tubercle on lateral radiographs of 11
knees. They reported that the radiographic
landmark of the femoral origin was located
in the anterior-proximal quadrant formed
by an extension of the posterior cortical
line and a horizontal line that intersects
the posterior aspect of Blumensaat’s line.
A high rate of inter- and intraobserver reliability was reported using this method for
femoral tunnel placement. Despite using a
similar quadrant referencing system, Barnett et al25 found the native MPFL femoral
insertion to be only 3.8 mm anterior to the
posterior cortical line—in contrast to Wijdicks et al,26 who reported 8.8 mm—and
0.9 mm distal to the posterior portion of
Blumensaat’s line. A significant relationship between limb rotation and the distance
of the femoral attachment from the posterior cortical line was observed.
Radiologic Evaluation
The isometric behavior of the MPFL
has been studied by several investigators.
Smirk and Morris21 evaluated 4 specimens
and considered isometric behavior to be
present if there was less than a 5-mm difference in length through the arc of motion from 0° to 120°. They found the most
isometric portion of the ligament to be
from the native patellar site to a point 1
cm anterior to the native femoral attachment. Steensen et al19 studied 11 cadaveric knees, evaluating if there were pairs
of points in the native attachments that
would be isometric. They measured length
change between 3 points (ie, superior,
middle, and inferior) of the native femoral origin and 3 similar points on the native patellar attachment. Length between
all combinations of femoral and patellar
points was measured at 0°, 30°, 60°, 90°,
and 120° of flexion. Although some pairs
did not show isometry, the combination of
Radiographic landmarks have been described to assist intraoperative placement
of the femoral attachment during MPFL
reconstruction (Figure 2).22 In a 2007 cadaveric study of 8 knees, Schöttle et al22
reported that the radiographic origin of
the MPFL could be identified on a lateral
radiograph of the knee 1 mm anterior to
an extension of the posterior cortical line
and 2.5 mm distal to a perpendicular line
intersecting the posterior origin of the medial femoral condyle. Using these radiographic landmarks, Redfern et al23 argued
that the point of intersection described
by Schöttle et al22 consistently placed the
femoral origin anterior and distal (2.5 mm
and 0.6 mm, respectively) to that of the
native MPFL. The authors23 suggested
that a femoral attachment placed more
posteriorly (0.5 mm anterior to the posterior femoral cortical line and 3 mm proxi-
Isometry
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Table
Summary of Studies Reporting the Anatomy of the Medial Patellofemoral Ligament
Mean
Thickness,
mm
Study
Specimen (No.)
Mean Length,
mm
Femoral Insertion
Patellar Insertion
Baldwin20
Cadaveric (50)
59.8±4.8
10.6±2.9 mm
(femoral attachment)
28.2±5.6 mm (patellar attachment)
-
Bony groove between
adductor tubercle
and medial epicondyle
Upper two-thirds
of patella
Feller et al16
Cadaveric (20)
-
-
-
Anterior to medial
epicondyle
Superomedial
border
Fujino et al10
Cadaveric (31)
-
-
-
10.6±2.5 mm distal
to adductor tubercle
along the long axis
of femur
-
LaPrade et al18
Cadaveric (8)
65.2
-
-
10.6 mm proximal and 8.8 mm
posterior to medial
epicondyle
1.9 mm anterior and
3.8 mm distal to adductor tubercle
Midpoint of ligament attached
41% of total
patellar height
Nomura et al14
Cadaveric (20)
58.8±4.7
12.0±3.1 mm (midportion)
0.44±0.19
Philippot et al15
Cadaveric (23)
57.7±5.8
12.2±2.6 mm
(femoral attachment)
24.4±4.8 mm (patellar attachment)
-
10.7±3.3 mm posterior and proximal to
medial epicondyle
11.2±5.9 mm anterior
and distal to adductor tubercle
Smirk and
Morris21
Cadaveric (25)
58.3
(range, 47.2-70.0)
-
-
Posterior portion of
Superomedial
medial epicondyle, 1
patella (88% of
cm distal to adducknees)
tor tubercle
Steensen et al19
Cadaveric (11)
-
17 mm at patellar
insertion
15.4 mm at femoral
origin
-
Anterior aspect of
medial epicondyle
6.1 mm from
superior edge
of patella to
superior edge
of MPFL
Tuxøe et al9
Cadaveric (39)
53
(range, 45-64)
19 mm (femoral
attachment)
-
Adductor tubercle
proximal to medial
collateral ligament
and distal to adductor magnus
Proximal twothirds of medial
patella
Width
9.5±1.8 mm proximal 27%±10% of
and 5.0±1.7 mm
patellar height
posterior from center
of medial epicondyle
61% of anteroposterior length of medial
femoral condyle
Upper half of
medial edge of
patella
Abbreviation: MPFL, medial patellofemoral ligament.
the superior femoral point to the inferior
patellar point showed relative isometry
(ie, less than 2 mm) between 0° and 90° of
flexion. Stephen et al27 reported the femoral attachment point midway between the
medial epicondyle and the adductor tubercle in 8 knees. During length testing, they
found that changes in position proximally
or distally had a larger effect than changes
anteriorly or posteriorly. Additionally, the
MONTH/MONTH 201x | Volume xx • Number X
authors27 reported that the femoral attachment was approximately 60% and 50% of
the total anteroposterior dimension from
the anterior and distal margins of the medial femoral condyle, respectively.
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A
B
Figure 1: Coronal (A) and sagittal (B) 3-dimensional computed tomography reconstruction showing the
femoral insertion site of the medial patellofemoral ligament (blue) in relation to the adductor tubercle (red)
and medial epicondyle (yellow).
Figure 2: Radiographic landmarks for placement of the femoral tunnel during reconstruction of the medial
patellofemoral ligament according to Schöttle et al22 (A), Redfern et al23 (B), and Wijdicks et al24 (C). Note
the crossing sign, indicating the presence of trochlear dysplasia.
Victor et al28 found the MPFL attachment site to be in a bony depression
proximal and posterior to the medial
epicondyle and distal and anterior to the
adductor tubercle using computed tomography for 12 cadaveric specimens.
The distance between attachment sites
decreased with increasing degrees of
flexion. A difference in length of 1 mm
was noted between 0° and 40°, 2.6 mm
4
between 0° and 90°, and 2.4 mm between
90° and 120° of flexion. The change in
tendon length was nearly linear between
40° and 120° of flexion.28
An in vivo study using magnetic resonance imaging to analyze MPFL length
changes in 20 patients was performed by
Higuchi et al12 in 2010. They found slight
changes in MPFL length between 0° and
60° and a decreased distance from 60° and
higher. The authors, therefore, advocated
for graft tensioning at 60° of flexion to
replicate the native biomechanics of the
MPFL. In a similar in vivo study by Yoo
et al,29 computed tomography scans of 10
patients revealed length changes between
4 femoral points and 2 patellar points. The
most isometric graft spanned from a point
midway between the medial epicondyle
and the adductor tubercle to a patellar
point located 45% of the distance between
the superior pole and the equator. In contrast to the study performed by Higuchi
et al,12 the authors29 recommended graft
tensioning at 30° of flexion on the basis of
their ideal virtual graft placement showing tightening until 30° of flexion with
progressive relaxation thereafter.
Tateishi et al30 reconstructed the
MPFL in 27 patients using a femoral site
between the medial epicondyle and the
adductor tubercle. The authors used intraoperative isometric testing and plain
radiographs to assess the position of their
femoral tunnel. Following isometric reconstruction of the MPFL (defined as
less than 5 mm of length change), they
compared the distance between the femoral and patellar insertion points on a lateral radiograph at terminal extension and
120° of flexion. Their findings implied
that 10 grafts elongated with flexion, 8
shortened, and 9 were isometric. A correlation with decreased motion at 4 and 8
weeks was noted in the patients with increased graft length with flexion.30
Discussion
Medial patellofemoral ligament reconstruction has emerged as a promising
treatment for recurrent patellar dislocation.31-33 There remains some uncertainty
as to the ideal site for femoral attachment
of the reconstructed ligament and how to
surgically achieve the desired position.
The current authors reviewed the literature on the anatomy of this ligament.
There is a trend to place the native attachment site between the medial epicondyle
and the adductor tubercle.
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Surgical goals can vary as one can attempt anatomic, isometric, or anisometric
graft placement. There may be benefits
and drawbacks to each approach. Anatomic reconstruction relies on previous
literature reporting cadaveric dissection
and/or radiologic guidance to aid graft
placement. As highlighted, there is some
variability to the findings of these studies and surgeons must choose the method
they consider most reliable on the basis of
available evidence. Studies reporting radiographic landmarks for femoral tunnel
placement have generally been limited by
the number of specimens included. These
studies often do not report the presence or
absence of abnormal anatomic factors often seen in patients with recurrent patellar
dislocation.34 It is possible that these studies report the native location of the MPFL
attachment in normal knees, which may
not be completely applicable for patients
with recurrent instability. Additionally, if
an anatomy-altering procedure, such as a
tibial tubercle osteotomy or trochleoplasty, is performed, the native anatomy of the
femoral attachment may no longer be an
appropriate site for graft attachment.
Intraoperative isometry testing may allow one to choose a femoral tunnel position that results in either an isometric or
anisometric graft. An isometric femoral
site may allow the reconstructed ligament to perform through the entire arc of
motion. This may be particularly helpful
when patella alta is present, as the native
ligament may be elongated (“MPFL longa”) and may become lax before trochlear
engagement. Isometric placement may
avoid overtensioning of the graft, as it can
be fixed while the patella is engaged in the
trochlea and would still be appropriately
tensioned when the knee is in extension
and the patella is no longer engaged. Isometric graft placement may also be advantageous when performing concomitant
procedures such as a tibial tubercle osteotomy or trochleoplasty, as the resultant
graft can be positioned to accommodate
the altered anatomy.
Anisometric placement may more
closely replicate the natural function of
the ligament. One must cautiously place
the graft to achieve the desired anisometry. It is important to avoid overtensioning the graft, which may result in an increase in patellofemoral contact forces
and potential graft failure.21,35 In a series
of 20 patients (23 knees), Thaunat and
Erasmus35 reported satisfactory results
following MPFL reconstruction with an
anisometric graft. The authors placed their
femoral tunnel using intraoperative isometry testing. At 3 months, 9 of 20 patients
possessed an extensor lag, which resolved
in all but 1 patient at 24 months. No patients in this series experienced recurrent
dislocation. The authors cautioned against
overtensioning the graft, especially in the
setting of preexisting patella alta. This
highlights a potential technical error for
MPFL reconstruction using an anisometric graft.35
current patellar instability are screened
for contributing anatomic factors (eg,
patella alta, increased femoral anteversion, increased tibial tubercle-trochlear
groove distance, and trochlear dysplasia)
and may undergo concomitant procedures
that alter the native anatomy of the patellofemoral joint. Isometric graft reconstruction allows for a reproducible femoral attachment site regardless of whether
the surrounding anatomy is being altered.
Although knowledge about patellar dislocation and associated anatomic factors is
expanding, there remain areas that are not
completely understood. Further research
could offer increased insight into treatment of this difficult problem.
Conclusion
2. Mäenpää H, Huhtala H, Lehto MU. Recurrence after patellar dislocation: redislocation
in 37/75 patients followed for 6-24 years.
Acta Orthop Scand. 1997; 68(5):424-426.
To the authors’ knowledge, there are
currently no studies comparing outcomes
between anatomic, isometric, or anisometric MPFL reconstruction. Patients
with recurrent dislocation of the patella
have a high prevalence of abnormal anatomic factors, including patella alta,36-38
increased Q-angle,39 rotational deformities,40 and trochlear dysplasia,39,41 which
may change the validity of previous cadaveric studies reporting the anatomy of
the MPFL insertion site. Isometric and
anisometric graft placement both may
have their strengths and weaknesses, with
no comparative research to support one
method over the other. The current authors
prefer a reconstruction resulting in an isometric MPFL graft. The rationale for this
includes the ability to create a graft of
appropriate tension throughout the arc of
motion while avoiding the potential technical errors associated with anisometric
graft reconstruction and those techniques
relying solely on radiographic landmarks.
Additionally, patients presenting with re-
MONTH/MONTH 201x | Volume xx • Number X
References
1. Camanho GL, Viegas Ade C, Bitar AC, Demange MK, Hernandez AJ. Conservative versus surgical treatment for repair of the medial
patellofemoral ligament in acute dislocations
of the patella. Arthroscopy. 2009; 25(6):620625.
3. Mäenpää H, Lehto MU. Patellar dislocation:
the long-term results of nonoperative management in 100 patients. Am J Sports Med.
1997; 25(2):213-217.
4. Palmu S, Kallio PE, Donell ST, Helenius
I, Nietosvaara Y. Acute patellar dislocation
in children and adolescents: a randomized
clinical trial. J Bone Joint Surg Am. 2008;
90(3):463-470.
5. Smith TO, Song F, Donell ST, Hing CB.
Operative versus non-operative management of patellar dislocation: a meta-analysis.
Knee Surg Sports Traumatol Arthrosc. 2011;
19(6):988-998.
6. Conlan T, Garth WP Jr, Lemons JE. Evaluation of the medial soft-tissue restraints of the
extensor mechanism of the knee. J Bone Joint
Surg Am. 1993; 75(5):682-693.
7. Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation
in the human knee. Am J Sports Med. 1998;
26(1):59-65.
8. Sallay PI, Poggi J, Speer KP, Garrett WE.
Acute dislocation of the patella: a correlative pathoanatomic study. Am J Sports Med.
1996; 24(1):52-60.
9. Tuxøe JI, Teir M, Winge S, Nielsen PL. The
medial patellofemoral ligament: a dissection
study. Knee Surg Sports Traumatol Arthrosc.
5
n Review Article
2002; 10(3):138-140.
10. Fujino K, Tajima G, Yan J, et al. Morphology of the femoral insertion site of the medial
patellofemoral ligament. Knee Surg Sports
Traumatol Arthrosc. 2015; 23(4):998-1003.
11. Amis AA, Firer P, Mountney J, Senavongse
W, Thomas NP. Anatomy and biomechanics
of the medial patellofemoral ligament. Knee.
2003; 10(3):215-220.
12. Higuchi T, Arai Y, Takamiya H, Miyamoto T,
Tokunaga D, Kubo T. An analysis of the medial patellofemoral ligament length change
pattern using open-MRI. Knee Surg Sports
Traumatol Arthrosc. 2010; 18(11):14701475.
13. Nomura E, Horiuchi Y, Kihara M. Medial
patellofemoral ligament restraint in lateral
patellar translation and reconstruction. Knee.
2000; 7(2):121-127.
14. Nomura E, Inoue M, Osada N. Anatomical
analysis of the medial patellofemoral ligament of the knee, especially the femoral attachment. Knee Surg Sports Traumatol Arthrosc. 2005; 13(7):510-515.
15. Philippot R, Chouteau J, Wegrzyn J, Testa R,
Fessy MH, Moyen B. Medial patellofemoral
ligament anatomy: implications for its surgical reconstruction. Knee Surg Sports Traumatol Arthrosc. 2009; 17(5):475-479.
16. Feller JA, Feagin JA Jr, Garrett WE Jr. The
medial patellofemoral ligament revisited: an
anatomical study. Knee Surg Sports Traumatol Arthrosc. 1993; 1(3-4):184-186.
17. Kang HJ, Wang F, Chen BC, Su YL, Zhang
ZC, Yan CB. Functional bundles of the medial patellofemoral ligament. Knee Surg Sports
Traumatol Arthrosc. 2010; 18(11):15111516.
18. LaPrade RF, Engebretsen AH, Ly TV, Johansen S, Wentorf FA, Engebretsen L. The anatomy of the medial part of the knee. J Bone
Joint Surg Am. 2007; 89(9):2000-2010.
19. Steensen RN, Dopirak RM, McDonald WG
III. The anatomy and isometry of the medial patellofemoral ligament: implications
for reconstruction. Am J Sports Med. 2004;
32(6):1509-1513.
20.Baldwin JL. The anatomy of the medial
patellofemoral ligament. Am J Sports Med.
6
2009; 37(12):2355-2361.
21. Smirk C, Morris H. The anatomy and reconstruction of the medial patellofemoral ligament. Knee. 2003; 10(3):221-227.
22.Schöttle PB, Schmeling A, Rosenstiel N,
Weiler A. Radiographic landmarks for femoral tunnel placement in medial patellofemoral
ligament reconstruction. Am J Sports Med.
2007; 35(5):801-804.
23. Redfern J, Kamath G, Burks R. Anatomical confirmation of the use of radiographic
landmarks in medial patellofemoral ligament reconstruction. Am J Sports Med. 2010;
38(2):293-297.
24. Wijdicks CA, Griffith CJ, LaPrade RF, et al.
Radiographic identification of the primary
medial knee structures. J Bone Joint Surg
Am. 2009; 91(3):521-529.
25. Barnett AJ, Howells NR, Burston BJ, Ansari
A, Clark D, Eldridge JD. Radiographic landmarks for tunnel placement in reconstruction of the medial patellofemoral ligament.
Knee Surg Sports Traumatol Arthrosc. 2012;
20(12):2380-2384.
26.Wijdicks CA, Westerhaus BD, Brand EJ,
Johansen S, Engebretsen L, LaPrade RF.
Sartorial branch of the saphenous nerve in
relation to a medial knee ligament repair or
reconstruction. Knee Surg Sports Traumatol
Arthrosc. 2010; 18(8):1105-1109.
27.Stephen JM, Lumpaopong P, Deehan DJ,
Kader D, Amis AA. The medial patellofemoral ligament: location of femoral attachment
and length change patterns resulting from
anatomic and nonanatomic attachments. Am
J Sports Med. 2012; 40(8):1871-1879.
28. Victor J, Wong P, Witvrouw E, Sloten JV,
Bellemans J. How isometric are the medial
patellofemoral, superficial medial collateral,
and lateral collateral ligaments of the knee?
Am J Sports Med. 2009; 37(10):2028-2036.
29. Yoo YS, Chang HG, Seo YJ, et al. Changes in
the length of the medial patellofemoral ligament: an in vivo analysis using 3-dimensional computed tomography. Am J Sports Med.
2012; 40(9):2142-2148.
30. Tateishi T, Tsuchiya M, Motosugi N, et al.
Graft length change and radiographic assessment of femoral drill hole position for medial patellofemoral ligament reconstruction.
Knee Surg Sports Traumatol Arthrosc. 2011;
19(3):400-407.
31. Ahmad R, Calciu M, Jayasekera N, Schranz
P, Mandalia V. Combined medial patellofemoral ligament reconstruction and tibial
tubercle transfer results at a follow-up of 2
years. J Knee Surg. 2017; 30(1):42-46.
32. Longo UG, Berton A, Salvatore G, et al. Medial patellofemoral ligament reconstruction
combined with bony procedures for patellar
instability: current indications, outcomes,
and complications. Arthroscopy. 2016;
32(7):1421-1427.
33. Schneider DK, Grawe B, Magnussen RA, et
al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations:
a systematic review and meta-analysis. Am J
Sports Med. 2016; 44(11):2993-3005.
34. Steensen RN, Bentley JC, Trinh TQ, Backes
JR, Wiltfong RE. The prevalence and combined prevalences of anatomic factors associated with recurrent patellar dislocation:
a magnetic resonance imaging study. Am J
Sports Med. 2015; 43(4):921-927.
35.Thaunat M, Erasmus PJ. The favourable
anisometry: an original concept for medial patellofemoral ligament reconstruction.
Knee. 2007; 14(6):424-428.
36. Simmons E Jr, Cameron JC. Patella alta and
recurrent dislocation of the patella. Clin Orthop Relat Res. 1992; 274:265-269.
37. Neyret P, Robinson AH, Le Coultre B, Lapra
C, Chambat P. Patellar tendon length: the factor in patellar instability? Knee. 2002; 9(1):3-6.
38. Insall J, Goldberg V, Salvati E. Recurrent
dislocation and the high-riding patella. Clin
Orthop Relat Res. 1972; 88:67-69.
39. Dejour H, Walch G, Nove-Josserand L, Guier
C. Factors of patellar instability: an anatomic
radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994; 2(1):19-26.
40. Hawkins RJ, Bell RH, Anisette G. Acute patellar dislocations: the natural history. Am J
Sports Med. 1986; 14(2):117-120.
41.Dejour H, Walch G, Neyret P, Adeleine
P. Dysplasia of the femoral trochlea [in
French]. Rev Chir Orthop Reparatrice Appar
Mot. 1990; 76(1):45-54.
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