Keywords
arthroscopy - epidemiology - knee - suture
Introduction
Meniscal ramp lesions are commonly associated with anterior cruciate ligament (ACL)
ruptures. A ramp lesion consists of meniscosynovial or meniscocapsular ruptures, which
can be difficult to diagnose arthroscopically from the anterior compartment, and which
significantly increase the anteroposterior and rotational instability of the knee
when compared to isolated ACL lesions.[1]
[2]
[3]
[4] Initially studied by Hamberg (apud Strobel[5]), the term “ramp lesion” was firstly attributed to these lesions to differentiate
them from other classical lesions of the posterior part of the medial meniscus.
Although there is a long history of recognition of meniscal ramp lesions, the topic
has been little studied in recent decades. This lack of previous importance attributed
to the topic is a consequence of factors such as the low sensitivity of magnetic resonance
imaging (MRI), with a high number of false-negatives, insufficient knowledge about
its biomechanical consequences, and an intuitive sense that these lesions can heal
spontaneously.[3]
[6] In addition, the lesion is located in a “blind spot” of the posteromedial compartment
of the knee, which makes it difficult to visualize through conventional arthroscopic
portals, requiring the surgeon to have a more accurate technical ability to access
and repair.[7] In 2014, Sonnery-Cottet et al.[8] introduced the concept of “occult lesions”, for meniscal ramp lesions that are not
visible by conventional arthroscopic approaches, proposing a systematic exploration
of the posterior segment of the medial meniscus by a posteromedial arthroscopy route.
The precise diagnosis of ramp lesions is also a challenge for radiologists. In 2017,
DePhillippo et al.[9] published an article showing a poor correlation between imaging and arthroscopy,
with more than half of the cases being underdiagnosed preoperatively. Edema in the
bone marrow in the posteromedial region of the medial tibial plateau appears to be
a suggestive radiological sign, being present in 72% of the cases of meniscal ramp
lesion.[9]
Although there are still no data on the epidemiology of ramp lesions in the Brazilian
population, the international literature shows an incidence between 9% and 24% in
ACL reconstructions (ACLRs).[1]
[6]
[7]
[10] The aim of the present study is to evaluate the incidence and epidemiological profile
of meniscal ramp lesions in patients undergoing ACLR, and to identify possible risk
factors associated with these lesions.
Materials and Methods
A retrospective analysis of the data of 824 ACLRs was performed through a consultation
of hospital records. The inclusion criterion was patients submitted to primary or
revision ACLR between July 2014 and April 2020. Patients undergoing concomitant surgeries,
such as multiligament reconstructions or osteotomies, were excluded. Preoperatively,
all patients had a complete rupture of the ACL, diagnosed based on clinical examination
and MRI scans. The study was approved by plataforma Brasil under CAAE number 27216819.2.0000.5496
Surgical Technique
The surgical procedures were performed by two surgeons who are specialists in knee
surgery and have great experience in ACLRs. The patients were positioned in a standard
way for arthroscopy ([Figure 1]). Meniscal and/or clinker lesions were addressed before ligament reconstruction.
Fig. 1 Lateral view of the position of the lower limb during reconstruction of the anterior
cruciate ligament (ACL), with the foot resting on the operating table, lateral support
at the level of the tourniquet, and the knee at 90o of flexion.
Initially, arthroscopic exploration of the knee compartments was performed. In cases
on which there was any sign of meniscal instability, such as increased anterior displacement
under traction, or when a fissure was observed in its lower leaflet, an investigation
was carried out in the posteromedial compartment, as proposed by Sonnery-Cottet et
al. [8] For the evaluation of the posteromedial compartment of the knee, the arthroscope
is maintained in the anterolateral portal and inserted through a space in the intercondyle
defined by the medial femoral condyle, posterior cruciate ligament (PCL), and tibia
([Figure 2]).
Fig. 2 Arthroscopy image of the space in the defined intercondyl through which the arthroscope
is inserted to access the posteromedial compartment of the knee. The correct point
is identified in the center of a triangle (in red) formed by the medial femoral condyle
(MFC), the posterior cruciate ligament (PCL), and the tibia.
In cases in which a meniscus fissure (ramp injury) was observed, repair was performed.
When there was also suspicion of the presence of a hidden ramp injury (type D),[11] meniscal integrity was tested with a needle, and then with a probe, inserted through
a posteromedial portal. The preparation of the posteromedial portal was made through
transillumination, which assistis in the visualization of veins to nerves that must
be preserved ([Figure 3]). The shaver blade was then inserted through the posteromedial portal, and both
surfaces of the lesion were scraped ([Figure 4]).
Fig. 3 Details of the opening of the posteromedial portal, with the arthroscope inserted
in the posteromedial compartment of the knee. (A) The use of transillumination prevents iatrogenic injury to vessels and nerves. (B) The needle is inserted in the direction of the lesion, to define the best point
to create the portal. (C) Under direct view, the portal is created with the use of a scalpel blade.
Fig. 4 Arthroscopy image, with the arthroscope located in the posteromedial compartment
of the knee, evidencing the meniscal ramp lesion. The scraping and regularization
of the edges of the meniscal ramp lesion is performed with a shaver blade. The outer
portion of the medial meniscus (OMM) and the inner portion of the medial meniscus
(IMM) are clearly visualized in the image.
For the sutures, a 25o suture hook (SutureLasso, Arthrex, Naples, FL, United States) loaded with an absorbable
monofilament thread no. 1 (PDS, Ethicon, Inc., Somerville, NJ, United States) was
used. The preparation of the stitches with sliding knots was carried out with the
help of a knot pusher ([Figure 5]). The satisfactory and stable repair was confirmed by evaluation using the probe
inserted through the anterolateral and posteromedial portals. Finally, the ACLR procedure
was performed with the preparation of independent anatomical tunnels (outside-in),
according to the Chambat technique.[12]
[13] Patients submitted to ramp lesion repair followed the same rehabilitation protocol.
Fig. 5 Arthroscopic image of the suture in the repair of the ramp lesion through the posteromedial
portal of the knee. (A) The 25o suture hook (SutureLasso, Arthrex, Naples, FL, United States) is inserted through
posteromedial portal for the repair of the lesion. (B) The suture is performed with the use of simple stitches, and with the aid of a knot
pusher (B).
Statistical Analysis
The quantitative variables were described by means and minimum and maximum values.
The qualitative variables were described by the distribution of absolute and relative
frequencies (%). The analysis of the relationship among the qualitative variables
was performed by the Chi-squared association test. The total and yearly proportions
of cases were analyzed by the incidence rates and their respective 95% confidence
intervals (95%CIs), and they were calculated by dividing the number of confirmed cases
and the aggregate of the population exposed in the period and expressed by 100. The
level of statistical significance adopted was of 5%, and the data were analyzed using
the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows,
IBM Corp., Armonk, NY, United States) software, version 24.0.
Results
The total number of patients submitted to ACLR included in the present study was 824.
Meniscal ramp lesion was observed and repaired in 87 (10.6%) patients. The characteristics
of the patients diagnosed with ramp lesion are shown in [Table 1].
Table 1
|
Characteristics
|
With injury – n (%)
|
No injury – n (%)
|
p-value
|
|
Gender
|
|
|
|
|
Male
|
76 (87.3%)
|
631 (85.6%)
|
0.718
|
|
Female
|
11 (12.7%)
|
109 (14.4%)
|
|
Laterality
|
|
|
|
|
Right
|
61 (70.1%)
|
403 (54.7%)
|
0.008*
|
|
Left
|
26 (29.9%)
|
337 (45.3%)
|
|
Ligament reconstruction
|
|
|
|
|
Primary
|
80 (91.9%)
|
694 (94.2%)
|
0.562
|
|
Revision
|
7 (8.1%)
|
43 (5.4%)
|
|
Age (years)
|
|
|
|
|
< 20
|
6 (6.9%)
|
102 (13.8%)
|
0.053
|
|
20–30
|
44 (50.6%)
|
267 (36.2%)
|
|
31–40
|
26 (29.9%)
|
255 (34.6%)
|
|
> 40
|
11 (12.6%)
|
119 (15.4%)
|
|
Average
|
29.9 (17–49)
|
31.4 (13–71)
|
|
Injury time (months)
|
|
|
|
|
≤ 3
|
28 (32.2%)
|
362 (49.1%)
|
0.008*
|
|
4–6
|
14 (16.1%)
|
102 (13.8%)
|
|
7–12
|
15 (17.2%)
|
79 (10.7%)
|
|
13–24
|
14 (16.1%)
|
58 (7.9%)
|
|
> 24
|
16 (18.4%)
|
136 (18.5%)
|
|
Average
|
16.4 (1–120)
|
19.7 (1–360)
|
Of the total number of patients with meniscal ramp injury, 76 (87.3%) were male, and
11 (12.7%), female. The mean age in this group was of 29.9 years (range: 17 to 49
years). From the 87 ACL reconstructions with associated ramp injury, 80 (91.9%) were
primary surgeries, and 7 (8.1%) were reviews, but with no statistical significance
between the groups (p = 0.562). Regarding laterality, the right knee was affected in 61 cases (70.1%),
and the left knee in 26 (29.9%), which was statistically significant (p = 0.008). The time between the lesion and ACLR was also statistically significant
(p = 0.008). In cases in which there was ramp injury, this time was of up to 3 months
(28 cases; 32.2%); between 4 and 6 months (14 cases; 16.1%); between 7 and 12 months
(15 cases; 17.2%); between 13 and 24 months 14 cases; 16.1%); and longer than 24 months
(16 cases; 18.4%), with an average of 16.4 months (range: 1 to 120 months). In cases
in which ramp lesions were not diagnosed, 362 (49.1%) had up to 3 months of injury;
102 (13.8%), from 4 to 6 months; 79 (10.7%), from 7 to 12 months; 58 (7.9%), from
13 to 24; and 136 (18.5%), for more than 24 months, with an average of 19.7 months
(range: 1 to 360 months).
Trauma related to sports or physical activities accounted for 76 (87.4%) of the total
number of cases. Among these, soccer was the most frequent cause, with 68 cases (78.2%)
(p = 0.599). Wrestling was the cause of 3 cases (3.4%); basketball, of 1 case (1.1%);
and other sports, such as volleyball, handball, rugby and cycling, of 4 cases (4.7%).
Among the causes not related to sports, there were 11 cases (9.3% of the total): 7
(5.9%) due to falls, and 4 (3.4%) due to traffic accidents ([Table 2]).
Table 2
|
Non-sport-related trauma
|
With injury – n (%)
|
No injury – n (%)
|
p
-value
|
|
Fall
|
7 (5.9%)
|
64 (54.2%)
|
0.939
|
|
Traffic accident
|
4 (3.4%)
|
43 (36.5%)
|
|
Total (100%)
|
11 (9.3%)
|
107 (90.7%)
|
|
Sport-related trauma
|
With injury – n (%)
|
No injury – n (%)
|
p
-value
|
|
Soccer
|
68 (9.6%)
|
548 (77.6%)
|
0.599
|
|
Wrestling
|
3 (0.4%)
|
25 (3.5%)
|
|
Basketball
|
1 (0.1%)
|
14 (2.0%)
|
|
Other
|
4 (0.7%)
|
43 (6.1%)
|
|
Total (100%)
|
76 (10.8%)
|
630 (89.2%)
|
The annual incidence rate is illustrated in [Table 3], and shows that, apart from 2018 (5.2%), there was a progressive increase in the
incidence of ramp injuries, ranging from 4.0% in 2014 to 20.6% in 2019.
Table 3
|
Year
|
Total exposed (n)
|
Ramp lesion (n)
|
Incidence (%)
|
95%CI
|
|
LL
|
UL
|
|
2014
|
124
|
5
|
4.00
|
1.70
|
9.10
|
|
2015
|
89
|
4
|
4.50
|
1.80
|
11.00
|
|
2016
|
110
|
12
|
10.90
|
6.40
|
18.10
|
|
2017
|
104
|
12
|
11.50
|
6.70
|
19.10
|
|
2018
|
116
|
6
|
5.20
|
2.40
|
10.80
|
|
2019
|
281
|
48
|
20.60
|
15.10
|
21.90
|
|
Total
|
824
|
87
|
10.60
|
8.60
|
12.80
|
Discussion
The main findings of the present study were the incidence of meniscal ramp lesions
in 10.6% of the patients with ACL injuries, and the highest incidence among those
with chronic ACL lesions. Other authors reported values between 9% and 24%.[1]
[6]
[9]
[10]
[14]
[15]
[16] Bollen[6] and Di Vico et al.,[15] reported lower incidences, of 9.3% and 9.6% respectively. Both studies included
a smaller sample, respectively of 183 and 115 patients. Liu et al.,[10] with a sample of 868 patients, observed an incidence of 16.6%, which is closer to
that found in the present study. The studies that found the highest incidences were
those by Seil et al.[14] and by Sonnery-Cottet et al.,[1] both with 24% of cases of ACL injury, and analyzing 224 and 3,214 patients respectively.
This great variation in the results found in the literature may be the result of certain
factors, such as the experience and ability of the surgeons to diagnose the lesion
during the arthroscopic procedure, and the number of patients included in the sample.
It was evident in the present study that there was an important annual increase in
the incidence of ramp injuries, from 4% to 20.6%. This is attributed to the fact that
the more familiar and experienced the surgeon is in investigating and repairing this
injury, the greater the number of diagnoses.[17]
The follow-up of patients submitted to ACLR, with the medial meniscus initially considered
healthy, showed that some patients still degrade the medial meniscus, although the
knee seems clinically stable.[18] This demonstrates that part of the lesions are underdiagnosed.
Regarding risk factors, it is known that the time between injury and ACLR is associated
with an increasing incidence of medial meniscus lesions.[1]
[19]
[20] Church and Keating[21] found an increase in the number of all types of meniscal lesions after twelve months,
recommending early ACLR to avoid these lesions. Liu et al.[10] showed that, within 24 months between the ACL injury and surgery, there was an increase
in the incidence of ramp injuries. In the present study, we identified that, of the
cases in which this time was shorter than 3 months, 32.2% had meniscal ramp lesion,
while 49.1% had no signs of injury. In chronic cases, with a time longer than 3 months,
there was a proportional increase in cases with ramp injury (67.8%) compared to cases
in which the meniscus was intact (50.9%) (p = 0.008).
Regarding the review cases, the literature[22]
[23]
[24] shows that knees submitted to ACL review have more intra-articular lesions than
knees submitted to primary reconstruction. Wright et al.[25] showed that up to 90% of the ACL revision cases presented a meniscal or condral
lesion, while 57% had both lesions at the time of surgery. Like Sonnery-Cottet et
al.,[1] we chose to include in the study patients submitted to ACL review, seeking to evaluate
whether this could also be considered a risk factor. Interestingly, the data found
in the present study did not show a higher incidence when it comes specifically to
meniscal ramp lesions in review cases (p = 0.562).
Despite the incidence of 10.6% of ACL reconstruction surgeries, the annual incidence
in the period studied ranged from 4.0% in 2014 to 20.6% in 2019. This escalation in
the number of cases draws attention, and may demonstrate a significant learning curve
in the diagnosis and treatment of these lesions. Therefore, we recommend the establishment
of routine systematic inspections of the posteromedial compartment of the knee in
ACL reconstructions, especially in chronic cases.
The present study has some limitations. During the first years, some cases may have
been underdiagnosed, due to the learning curve, presenting an incidence slightly below
the real one. Moreover, although both surgeons had great experience in ACLRs, they
were not necessarily at the same point of the learning curve for the diagnosis and
repair of meniscal ramp lesions during the period studied. This may have influenced
the final result and the annual incidence. Another possible bias is the fact that
both surgeons are right-handed, which may justify the greater number (statistically
significant) of right laterality, perhaps because it was easier from a technical point
of view, or because of the preference of the surgeons in the first cases. The present
study also has strengths, such as the significant sample (824 patients) compared to
the samples of other similar epidemiological studies in the literature. The fact that
the study involved more than one service strengthens the article, which analyzes the
epidemiology of these lesions under the same arthroscopic exploration protocol, however,
in different regions of the Brazilian territory. In any case, further epidemiological
studies should be conducted in different centers and regions of Brazil. With a more
information and data from different knee surgeons, there will be a better understanding
of the risk factors and the incidence of meniscal ramp injuries among the Brazilian
population.
Conclusion
The incidence of meniscal ramp lesions was of 10.6% in ACLRs, being more frequent
in chronic lesions. The annual incidence in the period studied ranged from 4.0% in
2014 to 20.6% in 2019.
