British Medical Bulletin Advance Access published January 31, 2013
Meniscal root tears: from basic science
to ultimate surgery
Rocco Papalia†, Sebastiano Vasta†, Francesco Franceschi†,
Stefano D’Adamio†, Nicola Maffulli‡*, and Vincenzo Denaro†
†
Department of Orthopaedic and Trauma Surgery, Campus Biomedico University of Rome,
Via Alvaro del Portillo 200, Rome, Italy, and ‡Centre for Sports and Exercise Medicine,
Barts and The London School of Medicine and Dentistry, Mile End Hospital, 275 Bancroft Road,
E1 4DG London, England
Sources of data: PubMed, Cochrane Library, Google Scholar and Ovid Medline
were searched in July 2012 to find literature on MRT tears. We reviewed the
literature on biomechanics, imaging features and current treatments of these
tears. Twenty-seven appropriate articles were identified and included in the
study: 6 biomechanical studies, 11 imaging-based investigations for diagnosis,
1 study on clinical diagnosis and 9 studies about treatment.
Areas of agreement: MRTs are infrequent, accounting for 10.1% of all
arthroscopic meniscectomies. When the damage occurs to the roots, the
transmission of the circumferential hoop tension is impaired and, consequently,
the menisci tend to be displaced anteriorly and posteriorly, altering the
biomechanics and possibly the kinematics of the knee.
Areas of controversy: Although the importance of the integrity of the meniscal
roots is well established, their diagnosis and treatment are still controversial.
*Correspondence address.
Centre for Sports and
Exercise Medicine, Barts
and The London School
of Medicine and
Dentistry, Mile End
Hospital, 275 Bancroft
Road, E1 4DG London,
England. E-mail:
n.maffulli@qmul.ac.uk
Growing points: Biomechanical and clinical studies demonstrate that surgical
repair of acute, traumatic meniscal root injuries fully restores the biomechanical
features of the menisci, leading to pain relief and functional improvement. The
current available surgical techniques for the meniscal root repair (suture anchors
and pullout repair) are comparable.
Level of evidence: IV.
Keywords: meniscus/meniscal root/knee arthroscopy/meniscal root repair
Accepted: January 7, 2013
British Medical Bulletin 2013; 1–25
DOI:10.1093/bmb/ldt002
& The Author 2013. Published by Oxford University Press.
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Background: In meniscal root tears (MRTs), the disruption of collagen fibers that
provide hoop strength results in extrusion of the menisci, altering their
biomechanical properties. Clinical diagnosis is difficult, but magnetic resonance
imaging usually allows to identify the lesion. Located into the vascularized zone
of the meniscus, management is preferentially arthroscopic, aimed at repairing
the lesions with arthroscopic transosseous sutures or suture anchors.
R. Papalia et al.
Introduction
Anatomy
The main functions of menisci are absorption and transmission of the
loads increasing the congruity between the femoral condyles and the
tibial upper surface. To absolve these functions, perfect stability and
biomechanical integrity of menisci are required to be strongly attached
to the tibial plateau and be hold in situ.6,7 Each meniscus has two
roots, one anterior and one posterior. The anterior root of the medial
meniscus inserts into the tibial intercondylar crest, the anterior root of
the lateral meniscus in front of the lateral tubercle. The posterior roots
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Menisci stabilize passively the knee, improve joint congruency and distribute the axial loads.1 The most common tears, involving the body
and horns, may lead to the development of cartilage degenerative
changes or accelerate their progression.2 – 5 When the damage occurs to
the posterior root, the transmission of the circumferential hoop tension
is impaired, and, consequently, the menisci tend to be displaced anteriorly and posteriorly,6,7 altering the biomechanics and possibly the
kimematics of the knee. Controversial in their etiology, tears to the
meniscal root are usually chronic, secondarily to degenerative changes
commonly observed in elderly patients, as expression of osteoarthritis.8,9 These tears, which are mainly of a degenerative nature, have to
be considered in the context of other disorders, including the lesions of
the medial collateral ligament (MCL), knee dislocations, reverse
Segond fracture and marginal fractures of the medial tibial plateau.10
Although clinical diagnosis is challenging, magnetic resonance
imaging (MRI) is sensitive and specific. Treatment is somewhat controversial: partial meniscetomy, preferred in the past, improves considerably symptoms and the evidence on its long-term effects on promoting
degenerative changes and frank osteoarthritis is still scanty.9,11 – 13 On
the contrary, as meniscal roots are well vascularized, the current trend
is to be minimally invasive, using arthroscopic approaches aimed at
repairing the lesion with transosseous sutures or suture anchors. From
the literature, some controversial points have emerged. Therefore, we
review systematically the literature to clarify some topical issues,
namely whether surgical repair restores the biomechanical properties of
an intact menisci and what is the best suture system to repair these
lesions. Also, we report on anatomy, biomechanical properties,
imaging features and current strategies of management of meniscal
tears. The process of articles selection is reported on Figure 1.
Meniscal root tears
insert into the posterior intercondylar area close to the tibial insertions
of the anterior and posterior cruciate ligaments; the insertion of the
lateral posterior root is relatively variable.14 The strongest root is
anterolateral, and the weakest is anteromedial.15
Pathogenesis
Etiologically, meniscal root tears (MRTs) may occur in an acute
setting, usually resulting from a traumatic insult, or they may be the
consequence of a chronic process, as a natural consequence of degenerative osteoarthritis. Understanding the actual etiology is essential to
plan appropriate management that may vary according to the cause of
the tear. An acute trauma, somewhat rare, usually occurs with the knee
hyperflexed while squatting down,8 or may result from multiligamentous injuries of the knee.13 The best approach is surgical repair
of the lesion, to correct the position of the meniscus and restore the
native biomechanics of the joint. On the other hand, chronic tears,
which are common, are often misdiagnosed, especially when multicompartmental osteoarthritis is expressed. Therefore, management has
to focus on how to recognize and manage the cause of the degeneration, rather than only repair the lesion. MRTs are more frequent to
the medial meniscus, particularly the posterior compartment, the area
designed to absorb most of the compressive forces applied on the knee.
The partial immobility of the posterior horn, related to the adhesion of
the medial meniscus to the MCL, makes this portion of meniscus more
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Fig. 1 Flow-chart illustrating the articles selection process.
R. Papalia et al.
susceptible to be damaged by axial and radial forces.16,17 A recent observational study of Hwang et al.18 reported that in females, higher
BMI, greater varus mechanical axis angle and lower sports activity
level are intrinsic risk factors predisposing to medial meniscus posterior
root tear. Interestingly, this study reported that oriental postural positions including the lotus position and squatting showed no contribution
to increased risk of medial MRT. The authors advanced the hypothesis
that intrinsic risk factors (similar to those that predispose to osteoarthritis) predispose to medial MRT. Finally, drilling the tibial tunnel too
laterally may lead to the disruption of the anterior root and horn of
the lateral meniscus.19
Both in animal and human specimens, menisci function as stabilizers of
the knee (Table 1).1,2,6,7,8 – 13 Allaire et al.,7 in a cadaveric study,
observed that a tear of the posterior root of the medial meniscus modifies markedly the tibiofemoral joint contact pressures and the kinematics
of the knee. A posterior root tear results in a 25% increase in peak
contact pressure, a significant increase when compared with the value
observed on the intact, controlateral side (P , 0.001), but similar to
the peak of contact pressure recorded following total medial meniscectomy. When the root is repaired, the peak contact pressure is restored.
In terms of kinematics, a root tear, similarly to a total medial meniscectomy, increases the external rotation and lateral translation of the
tibia on the femur and changes the varus alignment. Therefore, repairing a posterior root of the medial meniscus improves all the above-cited
biomechanical and kinematic parameters. In a human cadaveric
study,20 investigating the effects of avulsion of the posterior horn of
the medial meniscus showed that this lesion increases significantly the
posterior medial displacement of the meniscus from its anatomical position, decreasing instead the displacement anteriorly. A statistically significant increase in the gap formation was also recorded. Repairing the
medial meniscal root (MMR), native conditions are restored. Seo
et al.,21 in a study on 11 porcine knees, measured the mean contact
area and the peak tibiofemoral contact pressure at all angles of knee
flexion, showing significantly lower mean contact area and significantly
higher peak tibiofemoral contact pressures when a radial tear was
simulated. Interestingly, when compared with an unrepaired knee, the
pullout suture technique was demonstrated to reduce significantly the
peak contact pressure and increase the contact area from 30 to 908 of
knee flexion; no significant changes were recorded from 0 to 158.
Similarly, Marzo and Gurske-DePerio22 rated higher values of peak
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Biomechanics
Study
Material
Technique
Results
Conclusion
Clinical relevance
The effect of a
non-anatomic repair
of the meniscal horn
attachment on
meniscal tension and
to show that the
circumferential
tension of the
meniscus affects the
local stress of the
cartilage
8 porcine
knees
The tension at the horn
attachment was assessed
with the horn attachment at
its anatomic position and
repeated with the horn
attachment being displaced
medially or laterally by
3 mm. Then the local
deformation of the cartilage
under a femorotibial
compressive load was
measured at different levels
of meniscal hoop tension
Placing the horn attachment
3 mm medially decreased the
tension at the horn
attachment by 49 –73%,
depending on flexion angle
and femorotibial load. Lower
levels of meniscal hoop
tension caused increased
deformation of the cartilage
(P , 0.05), indicating increased
local stress
A non-anatomic
position of the horn
attachment strongly
affects conversion of
femorotibial loads
into circumferential
tension
There seems to be
only a narrow window
for a mechanically
sufficient repair of
root tears
Seo et al.21
To evaluate the
result of radial tears
at the root of the
posterior horn of
the medial meniscus
(PHMM) in terms of
tibiofemoral contact
mechanics and the
effectiveness of
pullout sutures for
such tears
11 mature
pig knees
After practicing a radial tear
at the root of the PHMM,
pullout sutures in the radial
tears of the medial meniscus
were used to repair. The
knees were tested at five
different angles of flexion
(08, 158, 308, 608, and 908)
under a 1500-N axial load. A
pressure sensor was used to
measure medial tibiofemoral
contact area and peak
tibiofemoral contact pressure
The mean contact area was
significantly lower, and the
peak tibiofemoral contact
pressure was significantly high
in knees with simulated radial
tears at all angles of knee
flexion when compared with
knees with intact menisci
(P , 0.0001)
Although repair of
tears of the PHMM
with the pullout
suture technique
aids in significantly
reducing
tibiofemoral peak
contact pressure
between 30 and 908,
it remains
significantly high at
0 and 158 of flexion
Pullout sutures for
radial tears at the root
of the PHMM may
lead to an increase in
peak medial
tibiofemoral contact
pressure and may be
prone to mechanical
failure, especially
during the stance
(loading) phase of
gait (mean, 158 of
flexion)
Marzo and
Gurske-DePerio22
To evaluate the
tibiofemoral contact
area and the peak
contact pressures
after the MRT repair
8 freshfrozen
human
cadaveric
knees
Tibiofemoral peak contact
pressures and contact were
measured in the intact knee,
after inducing MRT and after
repair by suture through a
transosseous tunnel
Avulsion of the posterior horn
attachment of the medial
meniscus resulted in a
significant increase in medial
joint peak contact pressure
(from 3841 to 5084 kPa) and a
significant decrease in contact
area (from 594 to 474 mm2).
Repair of the avulsion resulted
in restoration of the loading
profiles to values equal to the
control knee, with values of
3551 kPa for peak pressure and
592 mm2 for contact area
MRTs lead to
deleterious
alteration of the
loading profiles
The repair technique
described restores the
ability of the medial
meniscus to absorb
hoop stress and
eliminate joint-space
narrowing, possibly
decreasing the risk of
degenerative disease
Stärke et al.
Continued
Meniscal root tears
Page 5 of 25
Objective
23
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British Medical Bulletin 2013
Table 1 Overview of the biomechanical studies.
Hein et al.
20
Kopf et al.15
British Medical Bulletin 2013
Objective
Material
Technique
Results
Conclusion
Clinical relevance
To observe and
measure medial
meniscus (MM)
displacement in the
native knee, after
transection of the
MMR and after one
method to repair the
transected meniscal
root
7
fresh-frozen
human
cadaveric
knees
The knees were tested under
three conditions: native,
avulsed and repaired. Four
measurements were
obtained: meniscal
displacement anteriorly,
medially, posteriorly and gap
distance between the root
attachment site and MM
after transection and repair
The medial displacement of
the avulsed MM (3.28 mm) was
significantly greater
(P , 0.001) than the native
knee (1.60 mm) and repaired
knee (1.46 mm). Gap
formation is significantly
larger in the avulsed when
compared with repaired state
at 0 (P , 0.02) and 1800 N
(P , 0.02) and also larger with
loading in both avulsed
(,b0.05) and repaired
(,b0.02) conditions
Medial meniscal
posterior root
avulsion (MMRA)
results in a gap that
allows the meniscus
to displace and
extrude medially
from the joint.
Surgical fixation of
the posterior horn as
close as possible to
its root attachment
restores medial ME
to pre-avulsion or
smaller value
The clinical
significance of these
results substantiate
the theoretical, but
yet unproven
relationship between
MMRA and MM
extrusion seen on MRI
To evaluate the
maximum failure
load of the native
meniscal roots
(anteromedial,
posteromedial,
anterolateral, and
posterolateral) and
of three commonly
used meniscal root
fixation techniques
(two simple stitches,
modified Kessler
stitch and loop
stitch)
16
fresh-frozen
human
cadaveric
knees
The maximum failure load of
the 4 human native meniscal
roots was evaluated using 64
human meniscal roots.
Additionally, the maximum
failure load of the 3 fixation
techniques was evaluated on
24 meniscal roots: (i) two
simple stitches, (ii) modified
Kessler stitch and (iii) loop
stitch using a suture shuttle
The average maximum failure
load of the native meniscal
roots was 594 + 241 N
(anterolateral: 692 + 304 N;
posterolateral: 648 + 140 N;
anteromedial: 407 + 180 N;
posteromedial: 678 + 200 N).
The anteromedial root was
significantly weaker than the
posterolateral and
posteromedial roots (P ¼ 0.04
and P ¼ 0.01, respectively).
Regarding fixation techniques,
the maximum failure load of
the two simple stitches was
64.1 + 22.5 N, the modified
Kessler stitch was
142.6 + 33.3 N and the loop
was 100.9 + 41.6 N
The native
anterolateral root
was the strongest
meniscal root, and
the anteromedial
root was the
weakest meniscal
root. The modified
Kessler stitch was the
strongest technique
when compared
with the loop and
the two simple
stitches
Because the tested
fixation methods
restored the strength
of native meniscal
roots, rehabilitation
after meniscal root
fixation should
proceed cautiously
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Study
R. Papalia et al.
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Table 1 Continued
British Medical Bulletin 2013
Rosslenbroich
et al.24
To evaluate the
structural properties
of an arthroscopic
refixation technique
for MRTs
30
fresh-frozen
porcine
knees
The structural properties of
transtibial tunnel
reconstruction using one or
a double suture technique
were determined after a
cyclic loading protocol and
compared with an intact
posterior horn as control
group
Elongation after cyclic testing
was significantly lower for
intact and two suture
technique when compared
with single suture technique.
Stiffness was significantly
higher for intact constructs
with a mean of 53.7 (+6.5) N/
m and two suture technique
with 44.8 (+9.9) N/m when
compared with one suture
technique with a mean of 37.1
(+5.4) N/m. In elongation and
stiffness, no differences were
found between intact and two
suture technique. Ultimate
failure loads were 325.6 (+77)
N for the intact, 273.6 (+45.6)
N for two suture technique
and 149.8 (+24.3) N for the
one suture technique
The transtibial single
suture technique
showed significantly
higher elongation
and lower stiffness
and failure load
after cyclic loading
when compared
with the intact,
whereas a two
suture technique
showed no
difference in
elongation and
stiffness, however,
lower failure load
This arthroscopic two
suture technique
combines the
advantages of a
minimal-invasive
technique for
meniscal refixation of
the posterior horn,
providing sufficient
stability necessary for
the meniscal tissue to
heal
Meniscal root tears
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R. Papalia et al.
Clinical diagnosis
The clinical diagnosis of MRT is generally difficult. Patients may experience joint line pain, effusion and loss of knee flexion. The routinely
used meniscal tests are positive, and typically the McMurray test may
be positive without a mechanical click.25 However, there are no specific clinical signs, and, therefore, MRI and arthroscopic assessment are
necessary to make a definitive diagnosis. Arthroscopically, the ‘lift-off’
test of the posterior horn with a probe could help to definitely identify
the lesion.26
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contact pressure and lower readings of contact area when the posterior
root of the medial meniscus was avulsed from its insertion, with the
tendency of the posterior compartment of the medial tibiofemoral joint
to be overloaded, with the lateral compartment being relatively intact.
The transosseous suture technique restores the biomechanical properties essentially to those of the native knees. Stärke et al. 23 studied
whether a non-anatomical repair of the meniscal horn may change the
meniscal tension: measurements were made with the horn attached in
an anatomic position and displaced 3 mm medially or laterally from its
anatomical insertion. When the attachment site was displaced medially,
tension was decreased and the meniscal ring was expanded; when sited
laterally, the tension at the root attachment was significantly increased,
with higher local stress and predisposition to cartilage deformation.
When the meniscal root is repaired too tightly, the meniscus is overstressed. A human cadaveric study describing three different techniques
of repair of meniscal roots (two simple stitches, modified Kessler stitch
and loop stitch)15 showed that the anterolateral root is the strongest,
the anteromedial is the weakest, and the Kessler stitch technique presents better biomechanical properties than the loop and two simple
stitch configurations. However, none of the three techniques investigated was able to restore the strength of the native roots. A recent
study24 compared the structural properties of a transtibial tunnel reconstruction using a one or a double suture technique, using an intact posterior horn as control group. The transtibial single suture technique
showed significantly higher elongation and lower stiffness and failure
load after cyclic loading when compared with the intact structure.
A two suture technique showed no difference in elongation and stiffness; however, lower failure load was evident. The authors hypothesized that their technique could provide the stability necessary for the
meniscal tissue to heal.
Meniscal root tears
MRI diagnosis
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Despite the great efforts to find out and validate imaging criteria to
diagnose MRTs, there are not enough data yet to draw definitive
conclusions (Table 2). Anyhow, MRI demonstrated to be a sensitive
system to investigate this unique injury. Image findings in coronal and
sagittal MRI planes are proved to be reliable in diagnosis and axial
plane16,27,28 (Fig. 2). T2 weighted images are widely considered the
best sequence to display these tears showing maximum sensibility and
sensitivity values.29
Many authors investigated the relationship between the presence and
extension of meniscal extrusion (ME) showed on magnetic resonance
(MR) images and the eventual incidence of MRT. Costa et al.30 first
described the strong correlation between MRI-visible major ME
(3 mm), rather than minor (3 mm) and the occurrence of MRT
(P , 0.001). Then, Lerer et al.16 investigated and validated the statistical significance of ME as a diagnostic sign in MR images for MRT
(P , 0.0001). In a later study by Choi et al.,31 there was still evidence
of the close relation between increasing displacement (3 mm) and occurrence of arthroscopically confirmed posterior root tear (P , 0.001)
and severity of the eventual chondral lesion (P , 0.001). Finally,
Magee32 with a similar research came to the same conclusions, recording high prevalence of MRT in patients showing considerable extrusion
of medial meniscus on MRI. Choi et al.28 compared MRI findings of
several arthroscopically diagnosed medial MRTs to a simple medial
meniscus tear control group to find significant accuracy in the root tear
group (P , 0.05) and surprisingly describing axial plane as helpful in
diagnosis of MRT as other planes. Kijowski et al.33 recorded equivalent performance in detecting medial MRT (P ¼ 0.17–1.00) using
routine MR protocol versus FSE-Cube sequence, whereas FSE-Cube
had significantly lower sensitivity (P for detecting lateral meniscal tears
,0.05). Further studies by Kijowski’s group34 also showed how poor
outcome of an arthroscopic partial meniscectomy could be predicted
preoperatively by investigating image signs characteristic of MRT and
the related severity of meniscal exstrusion at MR imaging. Lee et al.29
had two radiologists retrospectively review MRIs from patient, who
had then undergone arthroscopic procedures to prove statistical high
sensitivity and substantial interobserver agreement in interpretation
and diagnosis of radial tears of MMR (k ¼ 0.93). De Smet et al.35
found that sensitivity and specificity of standard MRI criteria for diagnosis of a posterior root tear of lateral meniscus were 93 and 89%, respectively, after retrospective investigation of images using arthroscopy
as the reference standard. Lee et al.36 showed how all 36 surgically
Objective
Patient population
Outcome measures
Results
Conclusion
Choi
et al.28
MRI-based diagnosis
Study group: 30 patients
affected by MRTs;
control group: 30
patients affected by
medial meniscal tear
without MRTs
The radial tear on the meniscal
root of the medial meniscus in
the axial plane, the presence of
the truncation sign in the coronal
plane and the ghost meniscus
sign in the sagittal plane. ME in
the coronal plane was also
evaluated
The respective sensitivity, specificity,
positive predictive value and
negative predictive value were 93.3,
100, 100 and 93.8% for the axial
plane; 90, 100, 100 and 90.9% for
the coronal plane; 96.7, 96.7, 96.7
and 96.7% for the sagittal and 63.3,
90, 86.4 and 71.1% for the ME
The investigated features
are highly diagnostic for
MRTs, in particular the
axial plane is helpful to
detect medial MRT
Kijowski
et al.34
MRI-based diagnosis with a
three-dimensional isotropic
resolution intermediate
weighted fast spin-echo
sequence (FSE-Cube) when
compared with a routine
magnetic resonance protocol
at 3.0 T. The gold standard
was knee arthroscopy
250 patients who
underwent subsequent
knee arthroscopy
Axial frequency selective
fat-suppressed T2-weighted fast
spin-echo sequence, a coronal
intermediate-weighted fast
spin-echo sequence, a coronal
frequency selective
fat-suppressed
intermediate-weighted fast
spin-echo sequence, a sagittal
intermediate-weighted fast
spin-echo sequence, a sagittal
frequency selective
fat-suppressed T2-weighted fast
spin-echo sequence and a sagittal
FSE-Cube sequence
FSE-Cube and the routine MR
protocol had similar sensitivity
(95.5%/95.3%, respectively, P ¼ 0.94)
and similar specificity (69.8%/74.0%,
respectively, P ¼ 0.10) for detecting
156 medial meniscal tears. FSE-Cube
had significantly lower sensitivity
than the routine MR protocol
(79.4%/85.0%, respectively,
P , 0.05), but similar specificity
(83.9%/82.2%, respectively, P ¼ 0.37)
for detecting 89 lateral mensical
tears. For lateral meniscal tears,
FSE-Cube had significantly lower
sensitivity (P , 0.05) than the
routine MR protocol for detecting
19 root tears, but similar sensitivity
(P ¼ 0.17 –1.00) for detecting all
other tear locations and types
The power to diagnose
medial meniscal tear was
comparable between the
two techqinues; on the
contrary, lateral meniscal
tear and in particular
lateral MRTs were better
diagnosed by the routine
MR protocol
Choi
et al.31
To evaluate the relation
between ME on MRI and
tearing of the posterior root
of the medial meniscus
248 patients who
underwent knee
arthroscopy
The presence and extent of a ME
of 3 mm or greater was
considered pathologic.
Arthroscopic findings were
compared with respect to the
extent of ME
127 patients (51.2%) had a medial
ME of 3 mm or greater. Posterior
root tears were found in 66 (26.6%).
The mean ME in patients with root
tear was 3.8 + 1.4 mm, whereas the
mean extrusion of those who had
no root tear was 2.7 + 1.3 mm. An
association between pathologic ME
and root tear (P , 0.001) was found
Considerable ME
(.3 mm) can be
associated with tearing
of the medial meniscus
root
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Study
R. Papalia et al.
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Table 2 Overview on studies about imaging-based diagnosis.
16 patients affected by
tear of the posterior
root of the lateral
meniscus, compared to
45 patients with intact
posterior root of the
lateral meniscus
The root on the coronal and
sagittal images were assessed in
three locations: on the lateral
slope of the tibial eminence, at
the level of the lateral
intercondylar tubercle and
between the lateral and medial
intercondylar tubercles that are
also called the tibial spines
The sensitivity and specificity for
diagnosis of a root tear were 93 and
89%, respectively
The standard MR criteria
of meniscal distortion
and signal to the surface
can be used to diagnose
lateral meniscal root
tears
Lee
et al.29
Reliability and accuracy of
MRI for MRTs diagnosis
192 patients who
underwent arthroscopy
and MRI of the knee
were retrospectively
reviewed
The evaluated criteria were the
presence of an area of diffuse
high signal intensity in posterior
MMR on a sagittal image and of
linear or band-like vertical areas
of high signal intensity extending
through the posterior MMR on a
coronal or axial image
The sensitivity, specificity and
accuracy of MRI for one reader were
90% (26 out of 29), 94% (154 out of
163) and 94% (180 out of 192) and
for the other reader were 86% (25
out of 29), 95% (155 out of 163) and
94% (180 out of 192). Interobserver
agreement for radial tears of the
MMR was very high (k ¼ 0.93)
MRI-based diagnosis is
reliable and accurate.
Coronal T2-weighted
imaging is the most
useful MRI sequence
Kijowski
et al.33
MRI-based identification of
features negatively affecting
the clinical outcomes of
arthroscopic partial
meniscectomy
100 patients undergoing
arthroscopic partial
meniscectomy
Overall severity of knee joint
degeneration and severity of
each feature of joint
degeneration were assessed with
Boston Leads Osteoarthritis Knee
scoring system. Tear length was
measured, and type of meniscal
tear was classified
Poorer clinical outcome after
arthroscopic partial meniscectomy
(APM) was associated with greater
severity of cartilage loss and bone
marrow edema in the same
compartment as the meniscal tear,
greater severity of ME, greater overall
severity of joint degeneration, a MRT
and a longer meniscal tear at
preoperative MR imaging.
A significantly (P , 0.05)
increased relative risk
that a patient would not
definitely improve after
APM was observed, if a
MRT was present
Magee32
To correlate MR
examinations showing MEs
.3 mm beyond the tibial
margin with arthroscopic
findings
300 knee MRIs were
retrospectively reviewed
using knee arthroscopy
as reference standard
All patients underwent MRI of
the knee in coronal, axial and
sagittal planes on a 3T GE Signa
scanner. MR examinations were
reviewed for medial ME.3 mm
from the medial tibial plateau on
coronal images at the midpoint
of the medial femoral condyle.
Examinations positive for MEs
were assessed for the presence of
MRTs
42 demonstrated medial ME.3 mm.
Of these 42 patients, 34 had
meniscal degeneration, complex
tear or a large radial tear near to or
involving the meniscal root on MR
examination. A total of 33 of these
tears described on MR examination
were seen at arthroscopy. A total of
24 of these tears were root tears,
seven were complex tears and two
had severe meniscal degeneration.
There was one root tear described
on MR examination that was not
seen on arthroscopy
ME is highly prevalent in
MRTs on MR
examination, whereas it
is uncommon in patients
without ME. There may
be a subset of patients in
which the meniscal root
is stretched rather than
torn, resulting in ME
without a meniscal tear
present
Continued
Meniscal root tears
Page 11 of 25
MRI-based diagnosis of MRTs
retrospectively reviewing
MRI of patients who
underwent knee arthroscopy
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British Medical Bulletin 2013
De Smet
et al.35
Table 2 Continued
Patient population
Outcome measures
Results
Conclusion
Lee
et al.36
RMI-based diagnosis of MRTs
and the correlation of
medial MRT with other
associated knee
abnormalities
39 patients affected by
medial MRTs
arthroscopically
confirmed
Retrospective evaluation of Knee
MRI. Criteria for the diagnosis of
medial MRT required a tear
within 5 mm from the tibial
attachment site of the anterior or
PHMM
All 36 radial tears could be correctly
diagnosed by MRI, with findings
showing ghost sign on sagittal
images in 100% (36 out of 36),
vertical linear defect on coronal
images in 100% (36 out of 36) and
radial linear defect on axial image
in 94% (34 out of 36). However, all
3 complex tears were misdiagnosed
as radial tears on MRI. Moreover,
medial MRTs displayed a strong
association with DJD in 97% (38 out
of 39).
A high association
among medial MRTs and
DJD, cartilage defects of
the medial femoral
condyle and medial MEs
(.3 mm) were found
Lerer
et al.16
Assessment and evaluation
of a possible relationship
among medial ME (MME)
and DJD, and MME and
MMR pathology radial tear
and joint effusion
205 MR imaging
examinations of the
knee prospectively
evaluated
MME, medial compartment
marginal osteophytes, medial
joint space articular cartilage loss,
joint effusion, medial meniscal
tear and MMR pathology were
assessed. MME 3 mm was
considered abnormal
A strong association was found
(P , 0.0001) between .3 mm MME
and medial joint line osteophytosis
(77%), medial compartment
articular cartilage loss (69%), MMR
pathology (64%) and radial tear
(58%) when compared with knees
without these findings. Fifty-one
percentage of cases with a
moderate/large joint effusion had
,3 mm MME
MME .3 mm is strongly
associated with DJD,
MMR pathology and
radial tear
Costa
et al.30
Assessment and evaluation
of the relationship among
medial ME and severe
degeneration, large radial
tears, complex tears and
tears involving the meniscal
root
105 knee MRI
On mid-coronal images, extrusion
of the medial meniscus was
quantified in millimeters. A
separate, independent review of
the meniscus evaluated
degeneration severity and tear
(type and extent)
Tears involving the meniscal root
were seen in 3% (1 out of 34) with
minor extrusion and 42% (30 out of
71) with major extrusion (P , 0.001).
Substantial medial
meniscus extrusion
(.3 mm) is associated
with severe meniscal
degeneration, extensive
tear, complex tear, large
radial tear and tear
involving the meniscal
root
Yao
et al.3
MRI relationship between
‘presumptive subarticular
stress related’ and meniscal
disorders
1948 MRI evaluations of
the knee in 1850
patients
Standardized MRI imaging
protocol were utilized to assess
patients. The criterion for a PSSR
lesion was a subchondral marrow
edema pattern encompassing a
more focal, low-signal zone
adjacent to or contiguous with
the subchondral cortex
Twenty-five PSSR lesions were
identified among 1948 MRI
evaluations of the knee. Radial and
posterior root tears were more
common in knees with PSSR lesions
than in other knees with meniscal
tears (53% vs. 26%, P , 0.01)
PSSR lesions are
associated with meniscal
tears and, more
specifically, with
meniscal tear patterns
that dramatically
increase contact forces
across the knee joint
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British Medical Bulletin 2013
Objective
R. Papalia et al.
Page 12 of 25
Study
Meniscal root tears
discovered meniscal radial tears could be correctly detected by independent operators on preoperative MRIs during a retrospective study,
whereas all 3 complex tears involving posterior roots were misdiagnosed through their interpretation of images. Schlossberg et al.37
reported that most cases of pure ‘bucket handle’ tears of the medial
meniscus are diagnosed by central displacement of the fragment, rather
than ME in MR images, this last sign being related with lesions involving MRTs instead. Yao et al.3 data demonstrated that presumptive subarticular stress-related lesions, which are clearly recognizable on MRI,
are often associated with radial and posterior root tears (P , 0.001).
Because an acute root tear in the vascular zone has high chance to
heal after appropriate repair,38 it should be useful to easily differentiate
between an acute and a chronic injury at MRI scans. However, there
are no specific signs that allow to differentiate an acute from a chronic
root tear. Lerer et al.16 reported a high correlation between medial ME
and degenerative joint disease (DJD). The same authors advanced the
hypothesis that medial ME is likely a cause, rather than a consequence
of DJD. According to Lee et al.36 and Harper et al.,39 there are four
characteristic signs for detecting posterior root tears: truncated triangle,
cleft, marching cleft and ghost meniscus signs (Fig. 3). The use of all
four signs increased the detection rate for radial tears to 89%.39
British Medical Bulletin 2013
Page 13 of 25
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Fig. 2 MRI showing a ME.
R. Papalia et al.
Clinical features
The management of tears of the meniscal root is still controversial
(Table 3). Traditionally, partial or total meniscectomy is performed
even though the absence of the medial meniscus leads up to 25% increase in the tibio-femoral peak contact pressure.7,40 Therefore, new
strategies have been successfully proposed to address these tears such as
suture anchors, pullout or transosseus sutures (Figs 4 and 5). A retrospective study9 showed that partial meniscectomy improves significantly
the mean Lysholm score (from a preoperative value of 53 to postoperative value of 67), but radiographic findings and cartilage status
may deteriorate over time. Lee et al.41 assessed clinical, radiographic
and arthroscopic outcomes in patients undergoing pullout suture for
repair of a tear of the posterior root of the medial meniscus. At 2 years
from surgery, the Lysholm and Hospital for Special Surgery Scores were
significantly improved from their preoperative status (P , 0.0001), and
the Kellgren and Lawrence assessment was increased of one point in
only one patient. Ten of the 20 patients underwent second-look arthroscopy that showed a complete healing of all repaired menisci, with no
further cartilage lesions. From the comparison of partial meniscetomy
(28 patients) and pullout suture repair (30 patients),42 significantly
improved Lysholm and International Knee Documentation Committee
(IKDC) scores were observed in all patients, but repair provided significantly better scores and induced less degenerative changes and lower
Page 14 of 25
British Medical Bulletin 2013
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Fig. 3 MRI image showing a ‘ghost sign’.
Objective
Patients
Technique
Results
Conclusion
Kim et al.42
To evaluate functional
and radiographic results
of arthroscopic suture
anchor repair for
posterior root tear of
the medial meniscus
(PRTMM) and compared
with pullout suture
repair
51 consecutive patients
underwent arthroscopic
repair of PRTMM. 6 were
lost to follow-up, leaving
45 patients, with 22 in
group 1 and 23 in group
2
The repair techniques
were pullout suture
repair for group 1 and
suture anchor repair for
group 2
At 2 years post-operatively, both groups
showed significant improvements in
function (P , 0.05) and did not show
significant differences in Kellgren–
Lawrence grade (P , 0.05) when compared
with preoperatively. Mean ME of
4.3 + 0.9 mm (group 1) and 4.1 + 1.0 mm
(group 2) preoperatively was significantly
decreased to 2.1 + 1.0 mm (group 1) and
2.2 + 0.8 mm (group 2) post-operatively
(P , 0.05). At MRI, the gap distance at
PRTMM was 3.2 + 1.1 mm in group 1 and
2.9 + 0.9 mm in group 2 preoperatively
(P , 0.05)
The results show
significant functional
improvement in both the
groups. Reduction in ME
seems to be appropriate to
preserve its protective role
against progression of
cartilage degeneration
after complete healing at
PRTMM
Shelbourne
et al.45
To evaluate the
long-term radiographic
and subjective results of
patients with posterior
lateral meniscus root
tears (PLMRTs) left in
situ
Thirty-three patients
who had isolated
PLMRTs and .5 years
objective and subjective
follow-up were
evaluated and compared
with a matched control
group without meniscal
tears
Patients were evaluated
subjectively and
objectively using the
IKDC criteria
The mean subjective total score was
84.6 + 14 in the study group versus
90.5 + 13 in the control group (P ¼ 0.09).
Radiographs showed lateral joint-space
narrowing rated as normal in 19, mild in
10, moderate in 3, and severe in 1 versus
the control group that was normal in 28
and mild in 5 patients. The measured
amount of lateral joint-space narrowing
when compared with the other knee was
1.0 + 1.6 mm in the study group versus
0 + 1.1 mm in the controls on 458 flexed
posteroanterior radiographs (P , 0.006)
Although a mean of 1 mm
of joint-space narrowing
was seen in the study
group, there were no
significant differences in
subjective scores when
compared with matched
controls
Kim et al.43
To investigate the
clinical, radiologic and
arthroscopic findings of
pullout repair in medial
MRT and to compare
the results of pullout
repair and partial
meniscectomy
58 consecutive patients
with medial MRT who
underwent partial
meniscectomy (M group,
n ¼ 28) or pullout repair
(R group, n ¼ 30)
The patients were
evaluated by the Lysholm
knee score, IKDC
subjective knee score,
joint space narrowing
and Kellgren– Lawrence
grade on simple
radiographs. Medial ME
and the state of the
meniscus and articular
cartilage on MRI were
documented
Lysholm and IKDC scores improved
significantly in both groups (P , 0.05).
However, the R group had better Lysholm
and IKDC scores and less joint space
narrowing and progression of the
Kellgren– Lawrence grade than the M
group did (P , 0.05). In a subgroup analysis
of the R group, medial ME on MRI
decreased from 3.13 to 2.94 mm. Of the
patients, 28 (93.3%) showed complete or
partial healing of the meniscus. On MRI, 6
(20%) showed arthrosis progression. On
Arthroscopic pullout repair
of a medial MRT gave
significantly better clinical
and radiologic results than
partial meniscectomy and
sound healing with
restoration of hoop
tension of the meniscus
was observed on MRI and
second-look arthroscopy
Continued
Meniscal root tears
Page 15 of 25
Study
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British Medical Bulletin 2013
Table 3 Overview on studies about MRTs surgical treatment.
Study
Objective
Patients
Technique
Results
second-look arthroscopic examinations in
14 patients in the R group, 9 (64.3%)
showed normal fixation strength, 10
(71.4%) had normal restoration of hoop
tension, 5 (35.7%) showed arthrosis
progression and 2 (6.7%) had repeat tears
of the meniscus
A radiographic evaluation using the criteria
of Kellgren and Lawrence at final follow-up
showed an increase in radiographic grade
by 1 grade in only 1 knee. On the
second-look arthroscopies performed in 10
knees (47.6%), all repaired menisci had
healed completely without additional
chondral lesions in the knee. The mean
Hospital for Special Surgery scores
improved from 61.1 preoperatively to 93.8
at final follow-up (P , 0.0001), and the
mean preoperative Lysholm knee scores
improved from 57.0 to 93.1 at final
follow-up (P , 0.0001)
Conclusion
To evaluate the
short-term clinical
efficacy of arthroscopic
pullout suture repair in
treating posterior root
tears of the medial
meniscus
20 consecutive patients
(21 knees) treated by
arthroscopic pullout
suture
Clinical results by use of
the Lysholm knee and
Hospital for Special
Surgery scores and
radiographic grade were
evaluated, both
preoperatively and at
final follow-up. In
addition, the
second-look arthroscopic
findings for 10 knees
were analyzed
Ozkoc
et al.9
To define the clinical
features and
characteristics of radial
tears in the root of the
PHMM and to report
the outcome of
arthroscopic treatment
67 patients (70 knees)
All patients were treated
with arthroscopic partial
meniscectomy. Results of
MRI and surgical findings
of the study subjects
were analyzed and the
clinical results were
graded with the Lysholm
knee scoring scale and a
questionnaire. Radiologic
evaluation consisted of
preoperative and at the
latest follow-up
radiographs
The mean Lysholm score improved from a
preoperative value of 53 to a value of 67.
The average preoperative Kellgren –
Lawrence radiograph grade was 2 (range
0 –3 points), a value that increased to 3
(range 2 –4) at the latest follow-up that
showed a significant worsening. At MRI,
tears could be demonstrated in only 72.9%
of the patients, the rest of whom
demonstrated degeneration and/or fluid
accumulation at the posterior horn without
a visible meniscal tear
Partial meniscectomy
provides symptomatic
relief in most cases, but
does not arrest the
progression of
radiographically revealed
osteoarthritis
Lee et al.8
To determine the effect
of a radial tear on
degenerative medial
meniscus posterior horn
tear extrusion and to
identify predictors of
102 knees with medial
meniscus posterior horn
tears. Tears were
classified as root (n ¼ 17)
and non-root (n ¼ 85)
tears or as radial (n ¼ 46)
Groups were compared
in terms of absolute and
relative ME and the
proportion of knees with
major (.3 mm) extrusion
The radial group had greater mean
absolute (4 + 1 vs. 3 + 1 mm, P ¼ 0.001)
and relative (31 + 11 vs. 23 + 12%, P ¼
0.031) extrusion than the non-radial group.
The radial group also had a greater
proportion of major extrusions than the
ME was greater and more
severe in knees with a
radial tear component
than in knees without a
radial component. ME in
osteoarthritic knees was
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British Medical Bulletin 2013
Lee et al.41
Arthroscopic pullout
suture repair is an
effective treatment for
alleviating meniscal
symptoms
R. Papalia et al.
Page 16 of 25
Table 3 Continued
British Medical Bulletin 2013
medial meniscus
extrusion
and non-radial (n ¼ 56)
tears
Ahn et al.14
The authors reported
their experience with
the technique of
arthroscopic all-inside
repair for PLMRT
29 knees, 12 were of the
radial tear with oblique
flap, 4 were longitudinal
cleavage, 4 were of the
T-shape tear and 9 were
inner loss type
All-inside repair for the
radial root tear of Lateral
Meniscus
Second-look arthroscopy was performed on
8 patients at mean 20.1 months (range, 14 –
32 months) after surgery. Almost complete
healing was observed in the 8 patients
during second-look arthroscopy, even in
the white –white zone. The mean
subjective IKDC evaluation was 89.4 + 8.6.
The objective IKDC evaluation showed that
27 of the 29 (93%) patients had an overall
rating of normal and almost normal. The
mean Lysholm score was 92.8 + 3.7
PLMRT must be managed
with different method
with tears of other areas
because the tear
configuration is complex
than simple looking
Ahn et al.6
To evaluate the
effectiveness of
all-inside repair of
posterior lateral
meniscus root
full-thickness tears
27 patients affected by
anterior cruciate
ligament reconstruction
and PLMRT
All-inside repair of the
posterior lateral meniscus
root concomitant with
anterior cruciate
ligament reconstruction
There was no post-operative effusion,
joint-line tenderness, or positive McMurray
provocation testing observed at the last
follow-up. No statistically significant
improvement was observed in the coronal
plane in the 18 follow-up MRI scans
(P ¼ 0.096); however, sagittal extrusion
improved significantly (P ¼ 0.007)
After repair of PLMRTs,
MRI showed that the
displaced lateral meniscus
was reduced, mainly in the
sagittal plane
Jung et al.44
To evaluate the
subjective and objective
outcomes after repair of
medial MRTs
13 patients with a root
tear of the medial
meniscus
All-inside repair using a
suture anchor
Improvements in both the Tegner activity
level and Lysholm score were statistically
significant (P ¼ 0.001 and P ¼ 0.000,
respectively). Mean extrusion of the
mid-body of the medial meniscus was
3.9 mm (range, 2.2 –7.1 mm) preoperatively
and 3.5 mm (range, 1.2– 6.1 mm)
post-operatively. Extrusion was not
significantly decreased.
Follow-up MRI was
performed in 10 patients.
Five (50%) patients
showed complete healing;
2 of these 5 patients
showed complete healing
with isointense signal of a
normal meniscus and 3
showed intermediate
signal tissue at the
previous tear site without
any high signal cleft or
ghost sign. Four (40%)
patients showed partial
healing and 1 (10%)
showed no healing
Meniscal root tears
associated not only with
degenerative meniscal tear
but also with osteoarthritis
severity
Page 17 of 25
non-radial group (74% vs. 26%; P ¼ 0.016).
In contrast, the root tear and non-root tear
groups were similar in terms of mean
absolute (3 + 1 vs. 3 + 1 mm, P ¼ n.s.) and
relative (30 + 7 vs. 26 + 13%; P ¼ n.s.)
extrusion and in terms of proportion with
major extrusions (59 vs. 55%; P ¼ n.s.)
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R. Papalia et al.
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Fig. 4 Image showing pullout suture repair.
Fig. 5 Image showing suture anchor repair.
progression of the Kellgren –Lawrence grading over partial meniscectomy (P , 0.05). At second-look arthroscopic assessment, 9 of 14
patients (64.3%) who had undergone pullout repair presented normal
fixation strength, hoop tension was normal in 10 (71.4%), osteoarthritis
had progressed in 5 (35.7%) and repeated tears of menisci occurred in 2
(6.7%). Comparing functional and radiographic features after arthroscopic pullout suture (22 patients) and suture anchor (23 patients)
Page 18 of 25
British Medical Bulletin 2013
Meniscal root tears
Non-operative management
Non-operative management has been investigated in two studies. Lee
et al.8 reported that the incidence and degree of major extrusion
(.3 mm) were similar in knees with and without root tears, whereas a
radial tear was associated with a higher degree of MRT, than in knees
without a radial component. Shelbourne et al.45 reported that, after a
mean 10 years of follow-up, patients with a posterior lateral MRT left
in situ did not show significant differences in subjective scores when
compared with a control group, although a mean of 1 mm of jointspace narrowing was seen.
British Medical Bulletin 2013
Page 19 of 25
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repairs for management of tear of the posterior root of the medial meniscus,43 subjective evaluation and functional scores were significantly
improved from baseline status in both groups with no intergroup
differences (P , 0.05); radiographic findings were not significantly different from preoperative assessment in both groups (P , 0.05).
Post-operatively, on MRI scans, the gap distance at the tear site and
the ME were significantly reduced in both groups (P , 0.05), with no
significant intergroup difference. Cartilage degeneration progressed in
patients with incomplete meniscal healing, regardless of the repair performed. Encouraging results were reported by Jung and colleagues in a
study on 13 patients affected by medial meniscus posterior root tear
and treated with all-inside repair using 1 suture anchor, with 50% rate
(5 out of 10 patients) of complete healing at the MRI control.44
Concerning the lateral meniscus, Shelbourne et al.45 showed that prognosis does not change when a tear of the posterior root tear is left
in situ at the time of an anterior cruciate ligament reconstruction.
In this study, after anterior cruciate ligament (ACL) reconstruction,
33 patients with a tear of the posterior root of the lateral meniscus had
no significantly different subjective or objective scores than 33 patients
with no meniscal involvement, but joint-space narrowing was worse
for patients with MRTs. Ahn et al.14 evaluating 29 patients undergoing
arthroscopic all-inside repair for tears of the posterior root of the
lateral meniscus reported that the mean subjective IKDC was 89.4 +
8.6, and 27 of 29 patients (93%) were ranked as normal or almost
normal at objective IKDC assessment. Second-look arthroscopy, performed in 8 of the 29 patients, showed complete healing of the lesion
in all cases. In a subsequent study2 of the same authors, the postoperative MRI demonstrated that the extrusion of the lateral meniscus
was significantly reduced (P ¼ 0.007) on 18 patients undergoing
all-inside repair of the posterior lateral meniscus root concomitant with
anterior cruciate ligament reconstruction.
R. Papalia et al.
Post-operative management
The post-operative management of patients who underwent surgical
repair of MRT is a challenging time. Particular attention should be
paid before allowing patients for full extension and full weight bearing
because the integrity of the repaired meniscal root could be threatened
by an early rehabilitation.
Two authors41,43 were found to report on their post-operative protocol (Table 4).
Few studies reported on post-operative complication related to meniscal
root repair (Table 5). Mostly, they comprehend failure of the root
re-fixation and progression of the degenerative changes. Vyas and
Harner46 reported on the possibility that an insufficient reverse
Table 4 Post-operative management of patients who underwent surgical repair of MRT.
Study
Protocol
Kim
et al.43
A long cylinder leg cast is applied in the fully extended position for 2 weeks. At 2 weeks
post-operatively: non-weight bearing and a hinged post-operative brace and flexion of
the knee to 308 for the next 2 weeks. Thereafter, flexion is increased by 158 per week until
the sixth week to allow range of motion of 908. Deep flexion is forbidden until week 8
postopertively. Partial weight bearing allowed at 6 weeks post-operatively, followed by
full weight bearing at 8 weeks. Further flexion, squatting and return to sports are allowed
after 6 months.
Lee
et al.41
A long cylinder leg cast is applied for 2 weeks in a fully extended position, and a limited
motion brace is subsequently applied to control motion. Quadriceps sets and leg raises
several times daily are started. Patients are allowed for passive motion after the first 2
weeks and active motion up to 908 after the first 4 weeks. Flexion is progressively
increased by 108 a week until the eighth week to allow a range of motion of 1308. Partial
weight bearing is allowed at 6 weeks post-operatively, followed by full weight bearing at
8 weeks. Full flexion and squatting are allowed after 6 months.
Table 5 Complications of meniscal root repair
Page 20 of 25
Study
Complications
Jung
et al.44
One out of 10 patients showed no healing. One patient experienced a loosened suture
anchor at 8 months post-operatively. One patient suffered from a superficial infection
caused by methicillin-resistant Staphylococcus aureus at 6 weeks post-operatively after
high tibial osteotomy and meniscal root repair. The infection was managed by parenteral
antibiotics and debridement
Kim et al.42
Incomplete healing: 6 out of 17 in group 1; 2 out of 14 in group 2. Progression of
cartilage degeneration: 4 out of 17 in group 1; 2 out of 14 in group 2
British Medical Bulletin 2013
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Operative complications
Meniscal root tears
notchplasty could lead to inadequate availability of root tissue to fix,
iatrogenic ACL injury or damage of the neurovascular bundle of the posterior knee. Finally, there are generic complications associated with
knee surgery such as infection, arthrofibrosis and deep vein thrombosis.
Discussion
British Medical Bulletin 2013
Page 21 of 25
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MRTs are infrequent, accounting for 10.1% of all arthroscopic meniscectomies.9 However, the incidence is underestimated because they are
difficult to diagnose. Firstly described by Pagnani et al. in 1991,13 the
interest for these lesion has progressively grown. Essential for the
correct function of the knee,1 – 3 meniscal root disruptions may lead to
biomechanical effects that are comparable to those observed after total
meniscectomy.7 The posterior root of the medial meniscus is most frequently involved, probably in relation to the high load bearing that
stresses the posterior portion of this meniscus.47 In addition, as the
medial meniscus is generally subjected to greater loads than the lateral
meniscus, it is predisposed to increased risk of injury and degeneration
over time.17,30 Tears of the lateral roots are observed in 8 –10% of
patients with ACL disruption.35,48 The insult may be traumatic, especially in young patients,49 or, more commonly, expression of a degenerative process, in elderly patients.50
Diagnosis is challenging, complicated by the absence of specific signs
and symptoms, except in acute cases, when the extrusion is easily palpated over the anteromedial aspect of the knee, applying a varus stress
to the knee. In this case, a medial meniscus root tear may be suspected.25 However, diagnosis is based on MRI: a ME is a sign of a
MRT. An extrusion is considered pathologic when greater than 3 mm,
as found up to 64% of cases with patients with a MRT.16 Although
MRTs could be identified on both coronal and sagittal magnetic resonance images, such lesions are more clearly identifiable on two consecutive coronal magnetic resonance images.29 Once the presence of a
MRT has been detected, concomitant degenerative damage to the cartilage has to be assessed to understand which patients could benefit
from root repair. Because the meniscal root is vascularized,38,51 it can
be repaired. In acute cases, when severe cartilage damage has been
excluded, the root should be repaired to restore the circumferential
hoop tension, essential to guarantee the biomechanical functions of
weight bearing and shock absorption.
Many surgical options have been proposed. Most of the literature is
on the treatment of the medial MRTs. Partial or total meniscectomy,
commonly used in the past, relieves symptoms in most of patients, with
R. Papalia et al.
Page 22 of 25
British Medical Bulletin 2013
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no effect on the progression of the osteoarthritis.9 Recently, the pullout
suture52 and the suture anchor techniques53 have been proposed.
Pullout sutures reattach the detached portion of the meniscus to the
tibia through a tibial tunnel from the anteromedial cortex of the proximal tibia to the insertion site of the posterior horn of the meniscus,
using an ACL tibial drilling guide. Differently from a partial meniscectomy, pullout sutures restore the hoop tension of the menisci and lead
to better clinical and radiologic results,43 whereas similar results were
found at 2 years by Lee et al.41 Suture anchors may also be used to
repair these lesions and, as observed for pull-out sutures, significantly
improve the baseline condition,42 reduce ME and restore the knee function. Suture anchors are more advantageous than pullout suture
because they do not require a tibial tunnel, often technically demanding, especially for patients to undergo ACL surgery. Also, using a
suture anchor technique, it is possible to control adequately the tension
when securing the knots. Among suture technique of root fixation,15
the modified Kessler stitch provides a stronger fixation than loop and
two simple stitches. None of these three suture fixation models restores
the strength of the native roots, and, consequently, cautious rehabilitation has to be followed.
When the meniscal root is reattached non-anatomically, the conversion of femorotibial loads into circumferential tension may be altered,
with functional impairment of the knee. Therefore, the reattachment
should be more anatomical as possible.23
In our opinion, acute, traumatic MRTs should be repaired to restore
meniscal function and prevent osteoarthritis progression. Surgeon
should perform the technique with which they feel more confident, assuming that suture anchors and pullout techniques are comparable. On
the contrary, when these tears are present in the context of chronic cartilage degeneration, partial meniscectomy would be more indicated to
relieve symptoms. Although these lesions are considered to have the
same deleterious biomechanical effects as total meniscectomy, further
studies could be helpful to draw definitive conclusion inherent to their
diagnosis and surgical management. In conclusion, we propose the following treatment algorithm (Fig. 6).
About the post-operative period, in agreement with other
authors,41 – 43,54 the following protocol is suggested for the postoperative management of patients who underwent surgical repair of
meniscal root.
For the first two post-operative weeks, an articulated full length leg
brace is used, blocked in the fully extended position. Knee flexion is
then passively started (0–308) for 2 weeks, and afterward, it is allowed
a progressive increase of 208 per week until full flexion is recovered.
Active flexion is allowed after the fourth post-operative week in a safe
Meniscal root tears
Fig. 6 Treatment algorithm.
Conflict of interest
None declared.
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