Meniscal
tears of the knee are a frequent diagnosis among many sports injury settings.
Meniscal tears have accumulated great amounts of complications, a reason why understanding the risk factors for
meniscal tears is important, providing for a quicker and more accurate diagnosis
of injury. Lesions to the meniscus commonly occur in many sport scenarios where
tremendous dynamic demands are placed against the knee during distinct movements. Also, meniscal tears may occur within the workplace where constant and repetitive motions can develop issues.
Simple activities, such as standing, lifting, squatting, kneeling and
sitting, are considered to increase the risks of experiencing damage to the meniscus. The
time between ACL, or anterior cruciate ligament, ruptures and surgical
reconstruction procedures have also been acknowledged to increase the chance for meniscal
lesions. Various components contributing to this type of injury have been identified, however, there’s limited research to support them.
Scientists at the University of Amsterdam, published a systematic review
along with a meta-analysis, which investigated several key risk factors for
meniscal tears.
The menisci are two semilunar ridge-like structures, which are located on the medial and lateral surface of the tibial plateau. The menisci
function by allowing the convex surface of the femur to articulate on the
concave surface of the tibia. In addition, the menisci enable the conversion
of weight as well as the absorption of shock during dynamic movements, acting
to protect the articular cartilage. Meniscal lesions can be distinguished as
acute or degenerative, manifesting in different forms, such as a bucket handle
tear, a horizontal tear, or a degenerative tear.
Anterior View of Right Knee
Superior View of Tibial Plateau and Forms of Meniscal Lesions
Acute Risk Factors for Meniscal Lesions
In one study, weight bearing after an individual experienced trauma, was determined to pose a moderate danger in the development of meniscal tears. Researchers from Lund University in Sweden identified that individuals with an ACL injury who engaged in non-weight bearing activities were less likely to experience further damage to the meniscus. Often, ACL injuries occur in load bearing positions which frequently result in higher joint compression forces of the tibiofemoral compartment. Thus, the well-known term, the unhappy triad, has been more appropriately termed the unhappy compression injury. The unhappy triad refers to trauma involving the ACL, medial collateral ligament and the medial meniscus. It’s ultimately essential to stabilize the joint of the knee through the use of conservative or surgical procedures to prevent additional compression against the meniscus. It was concluded that weight bearing during an injury revealed a moderate chance of injury to the meniscus, however, the authors were unable to determine whether a considerable effect existed.
Degenerative Risk Factors for Meniscal Tears
Two research studies determined that an individual’s body mass index, or
BMI, may be consequential with degenerative meniscal changes. Scientists
from Boston University evaluated the BMI of 991 participants, of which 565 were
female and 426 were male. The assessment concluded that females with a
meniscal tear had a considerably higher BMI, approximately 29.9 percent, than
females without meniscal damage, approximately 27.9 percent. However, there
were no statistical differences in body mass index for males, with or without
meniscal damage. An identical research study distinguished a considerable difference
in meniscal tears among participants with a BMI of 25 to 30 kg/m2, a 76 percent
of incidence, when compared to participants with a BMI of less than 25 kg/m2,
with a 34 percent of incidence. It was concluded, through statistical analysis,
that a BMI greater than 25 kg/m2 produced a greater classification for meniscal
damage than those with a lower BMI. It’s important to keep in mind that these
statistics don’t simply involve individuals of obese proportions but it also
includes those who maintain a greater muscle mass as well as increased body
mass.
As previously recognized in other studies, age is considered to be a critical
element for these particular knee injuries. Researchers have confirmed that
older individuals may in fact experience greater meniscal trauma. For instance,
approximately 19 percent of females and 32 percent of males ranging from 50 to
59 years of age, faced meniscal destruction, in comparison to 51 percent of
females and 56 percent of males ranging from 70 to 90 years of age, who
presented meniscal trauma. The researchers concluded that people aged 60 years
old and over were considerably more probable to suffer from degenerative
meniscal tears than someone under 60 years of age. Regardless, the results of
the study failed to explain that individual’s younger than the age group
provided for the study could also sustain meniscal tears. As a matter of fact, knee
complications can also be considered to be some of the most prevalent types of
youth injuries, although further research is required to properly determine the
statistics of youth athletes with meniscal lesions.
Furthermore, gender has also been determined to be an essential risk
factor for injuries to the meniscus, as identified in other studies. Additional
research from the Boston University evaluated the relationship between meniscal
tears, pain and osteoarthritis in 154 patients with identified symptoms of knee
osteoarthritis. Using MRI scans, the end results demonstrated that 91 percent
of individuals presented a medial or lateral meniscal tear, in which males were
identified with a significantly higher prevalence of meniscal lesions than
females. Another study distinguished the features of meniscal lesions in 991
individuals through the utilization of MRI scans. Again, males demonstrated a
considerably higher incidence of meniscal tears among all age groups, although
females diagnosed with meniscal degeneration were categorized within the 70 to
90 years of age group. Whether the higher occurrence of injury in males was due
to greater participation in sport or due to occupational activities, such was not
determined in the study.
Three distinct research studies found that kneeling and squatting for
more than one hour per day could influence the development of meniscal tears. Individuals
whom participate in certain trades or professions, such as carpentry, electrician
and plumbing, positions which have widely been occupied by males, repetitively
and constantly kneel and squat as a part of their average work day. Research
carried out at Southampton University in England determined that 59 participants
experienced locking of the knees where 29 were exposed to kneeling and 30 were
exposed to squatting in their workplace. Of these 59 individuals, some which
may have crossed over in both categories, 69 percent and 73 percent correspondingly
consulted an orthopedic surgeon. These participants reported engaging in
frequent kneeling and squatting positions while at work, however, several
participants also reported participating in specific sports, such as football,
which is also considered another risk factor for meniscus lesions.
Sitting for more than two hours per day was believed to decrease the
risk of meniscal tears. Two studies conducted by the same leading author from
Southampton University, focused to determine the risks of sitting. Also,
sitting for extended periods of time was believed to incline an individual to
develop other knee conditions, such as patellofemoral pain, also referred to as
movie/theatre sign, of which sitting is believed to be a risk factor. Although
studies concluded that sitting doesn’t increase the chance of further damaging
meniscal tears, it was determined to potentially create issues on other areas
of the knee.
Standing or walking for more than two hours per day for 12 months before
experiencing symptoms, as compared to less than two hours per day, were thought-out
to influence the development of meniscal lesions. Two additional research
studies evaluated the effects of standing and walking for extended periods of
time. The results concluded that from 71 participants who were disclosed to
prolonged standing or walking for more than two hours per day, 54 percent had
consulted an orthopedic surgeon due to symptoms of meniscal damage. In
comparison, walking and standing was concluded to be effective, in terms of
energy expenditure, mechanical bone loading, cardiovascular fitness and overall
health, apart from other perspectives.
Walking more than two miles per day within 12 months before symptoms,
was determined to have a very low chance of causing meniscal lesions. The
health benefits of walking outweigh the possibility of knee injuries and
therefore, should not be excluded otherwise unless the symptoms prevent the
individual from participating.
Moreover, climbing more than 30 flights of stairs per day within the 12
months prior to the onset of pain and discomfort, was found to considerably
affect the individual, aside from climbing stairs 30 times per day, lead to an
increased possibility of knee injuries. During a study, 17 male participants
reported meniscal related symptoms, such as locking, when climbing stairs, with
59 percent resulting in a consultation with an orthopedic surgeon.
Carrying an excess of 10 kg, 25 kg and 50kg more than 10 times per week
concluded in two studies that there was a significant effect against the
structures of the knees, increasing the risk of a meniscal lesion.
Acute and degenerative meniscal tears were examined in a current
research study. Utilizing a community sample of 2,806 males in the south of
England, by means of a questionnaire, 1,404 participants answered where 762 described experiencing prior symptoms of knee injury. Of the 762 participants with
symptomatic knees, 127 claimed feeling symptoms of locking during one or more
occupational activities, which lasted longer than 24 hours. The results concluded the potential increased risk of meniscal lesions within the 20-59 age group category.
Laxity of the Knee Joint
Anterior
cruciate ligament, or ACL, injuries where there’s an extended period of time
till an athlete will receive reconstructive surgery have been well recorded as
an influence towards the development of meniscal lesions. An ACL deficient knee
requires the menisci to function accordingly as a stabilizing component along
the posterior-anterior, valgus-varus and internal/external rotation movements. While
rehabilitation methods such as chiropractic adjustments and manual mobilization
and manipulation techniques, or physical therapy may be utilized to help
improve an individual’s symptoms as well as increase the strength of the
surrounding structures. However, a majority of meniscal injuries may require
surgical interventions to properly repair them. Researcher’s findings coincided
with previous research concluded that an ACL deficient knee posed a risk to
meniscus trauma but identified that this was consistent with the medial but not
lateral meniscus. The authors of the research study stated that this altered
consistency may be due to the medial meniscus being fixed to the joint capsule.
In comparison, the lateral meniscus is not firmly attached to the joint capsule,
acquiring more mobility within the joint which explains the difference in
injury incidence.
It was recognized that from 3,475 individuals with previous ACL injuries,
1,638, approximately 47 percent, were diagnosed with meniscal tears. The
authors added that for each month that went by for individuals that experienced
an ACL rupture, there was an exponential chance of meniscal trauma of only 1
percent. Additionally, the presence of a degenerative meniscal lesion increased
an individual’s risk of suffering further trauma to the knee by 1.6 to 2.0
percent.
The Risk of Playing Sports with Meniscal Tears
In conclusion, numerous factors have been recognized as
potential risk components which might predispose an individual to experience a
greater incidence of meniscal tears. An injury to the meniscus can be experienced by anyone within the general population and athletes alike and these should not
be ruled out to only develop in a single sub-group based on other research
studies. Ultimately, the classified risk factors tremendously were established to possibly increase the
chance for an individual to experience specific types of knee injuries. Although
several research studies cover a large variety of risk factors for the general
population and athletes, these were very limited as the majority were only backed by a few studies.
By Dr. Alex Jimenez
