The lateral meniscus is the cartilage cushion on the outer side of the knee. In my practice, I often explain to patients that it works like a shock absorber, load distributor, and stabilizer inside the joint. When it is injured, the knee may become painful, swollen, unstable, or mechanically blocked during movement.[1][2]
In Bangladesh, I commonly see lateral meniscus injuries after football, cricket, badminton, gym twisting, stair slips, motorcycle-related falls, and sudden pivoting movements. But not every lateral meniscus problem is caused by one big injury. Some patients, especially older adults, develop degenerative tears over time as the tissue becomes weaker and less resilient.[1][3]
What Makes the Lateral Meniscus Different
The knee has two menisci: the medial meniscus on the inner side and the lateral meniscus on the outer side. The lateral meniscus is more mobile than the medial meniscus. That mobility gives it some protection, so it is generally less commonly torn in isolation. However, it is frequently involved in traumatic knee injuries, especially when there is an associated ACL injury.[2]
StatPearls notes that the lateral meniscus is important for shock absorption, load transmission, lubrication, and stability. Damage to it may increase joint stress and contribute to later cartilage degeneration or osteoarthritis.[2]
One important point I want Bangladeshi patients to understand is that a “cartilage tear” in the knee often refers to the meniscus, not the smooth joint surface cartilage. The treatment and recovery can be very different depending on the exact structure involved.
How Lateral Meniscus Injuries Happen
Lateral meniscus injuries can happen in two broad ways.
Acute Traumatic Tear
This usually occurs when the knee is bent and the body twists over a planted foot. Sudden rotation with axial load is a classic mechanism. It can happen during sports, road traffic falls, or abrupt directional changes.[1][2]
Degenerative Tear
This is more common in older adults. The meniscus becomes worn over time, and sometimes a simple movement, such as getting up from a chair or turning awkwardly, is enough to produce pain and a tear pattern in already weakened tissue.[1][2]
The AAOS also notes that sports-related meniscus injuries often occur along with ligament injuries, especially ACL tears.[1] That is why I never assess a suspected meniscus tear in isolation without also checking stability.
Common Symptoms of a Lateral Meniscus Tear
Patients do not all present the same way, but common symptoms include:
- pain on the outer side of the knee
- swelling or stiffness
- pain with twisting, squatting, or pivoting
- catching or clicking inside the knee
- locking of the knee
- feeling that the knee is not moving normally
- difficulty fully bending or straightening the knee[1][3][4]
According to AAOS, many patients can still walk after a tear, and some athletes even continue briefly, but over the next two to three days the knee often becomes stiffer and more swollen.[1] This delayed swelling pattern is something I see often in Dhaka after sports injuries.
When the Problem May Be More Serious
Not all lateral meniscus injuries are emergencies, but some features should make you seek evaluation sooner:
- a twisting injury followed by swelling
- inability to fully extend the knee
- repeated locking
- major joint swelling
- inability to bear weight
- the sensation that the knee is giving way
- associated pop at the time of injury
- suspected ACL injury with instability[1][3][4]
If the knee is hot, red, and swollen without a clear injury, I also think beyond a meniscus tear and consider infection, gout, or inflammatory arthritis.[3]
How I Evaluate Suspected Lateral Meniscus Injury
When I evaluate patients with this complaint, I begin with the history because the mechanism often gives the first clue.
Mechanism of Injury
A planted foot with twisting is very suggestive. A dashboard injury, fall, or sports pivot can point toward a traumatic tear, sometimes with additional internal derangement.[4]
Location of Pain
Pain along the outer joint line raises suspicion for lateral meniscus involvement, especially if it is reproducible on examination.[1]
Mechanical Symptoms
Catching, clicking, and especially locking matter. A locked knee may indicate a displaced tear that needs more urgent attention.[3][4]
Swelling Pattern
Effusion after injury can suggest internal derangement. The AAFP notes that positive physical findings with acute effusion increase the likelihood of significant internal knee pathology.[4]
What the Physical Examination Looks For
On examination, I usually assess:
- lateral joint line tenderness
- effusion
- range of motion
- pain during squatting
- ligament stability
- meniscal provocative tests such as McMurray and sometimes Thessaly if appropriate[1][4]
AAOS highlights joint line tenderness and McMurray testing as important parts of meniscal assessment.[1] The AAFP review also notes that an abnormal McMurray or Thessaly test strongly suggests meniscal injury, while a normal Thessaly test may help lower suspicion in some settings.[4]
That said, a painful swollen knee may limit these tests during the first visit. In real practice, sometimes I reassess once the swelling and guarding improve.
Do You Need X-Ray or MRI?
X-Ray
An X-ray will not show the meniscus itself, but it is still useful to look for fracture, alignment issues, and osteoarthritis.[1][4]
