Computer Vision AG-Blog

The Lexicon of Ligaments: Understanding Knee Injuries

Stefan Voser — Wed, 15 Jul 2026 13:06:49 GMT

PCL…Public Limited Company? Printer Control Language? Python Coding Layer?

MCL and LCL? These are Roman numerals…right?

If—like me--you’re not in the field of orthopedics, you might wonder what these abbreviations stand for. I was familiar with the letters ACL in relation to knee injuries, but only because ACL sprains and tears are so common, especially in athletes.

So what do all these baffling letters mean in medicine?

ACL= Anterior Cruciate Ligament: The ACL runs diagonally down the front of the knee. The ACL prevents the tibia (shinbone) from sliding out in front of the femur (thighbone) and provide stability in the knee when the body is rotating. People with visible scars running vertically down the front of their kneecaps might have had surgery to repair an ACL tear.
PCL= Posterior Cruciate Ligament: The PCL runs vertically down the back of the knee. It prevents the tibia (shinbone) from sliding out behind the femur (thighbone). Injuring your PCL requires a powerful force, like the impact of hitting your bent knee against your dashboard in a car accident.
MCL = Medial Collateral Ligament: The MCL runs along the inside of the knee. Its function is to prevent the leg from extending too far inward. Direct contact from a kick or other impact to the outside of the knee can push the knee sideways, putting pressure on the MCL on the inside of the knee.
LCL = Lateral Collateral Ligament: The LCL runs along the outside of the knee. Its function is to prevent the leg from extending too far outward. Severe impacts to the inside of the knee can strain the LCL, causing the ligament to tear.

There are a ton of ways in which a person could injure the ACL. ACL sprains are common in a wide range of sports activities, and the characteristic loud pop, sudden instability, and immediate swelling are telltale signs that you’ve seriously injured your ACL.

MCL injuries are nearly as common as ACL injuries, and make up large percentage of knee injuries in contact sports like hockey or American football. Orthopedic surgeons categorize MCL injuries in three grades:

Grade 1 — Minor injury with minimally torn ligament fibers. Some tenderness and minor pain.
Grade 2 — Moderate injury with a partial tear. Noticeable looseness in the knee when moved by hand accompanied by major pain, tenderness, and sometimes swelling at the inside of the knee.
Grade 3 — Severe injury with complete tear. Considerable pain and tenderness at the inside of the knee; some swelling and marked joint instability. This severity of injury is frequently accompanied by a tear of the ACL.

To diagnose the severity of the injury, evaluation by an orthopedic specialist is necessary, often in conjunction with MRI. Because it creates a clear picture of the soft tissues in the knee, MRI has an accuracy rate of nearly 90 percent in determining whether and how badly a medial collateral ligament is torn.

LCL injuries are categorized by similar gradations. They are less common than MCL injuries, and they also do not heal as well. While MCL injuries rarely require surgery, severe LCL tears may require surgery followed by physical rehabilitation.

LCL tears rarely occur in isolation; they usually happen in conjunction with another knee injury. Unlike most knee ligament tears, which occur frequently during high-impact sports, isolated LCL tears ironically sometimes result from the attempt to achieve certain seated yoga poses such as the full lotus or Eka Pada Sirasana (in which the foot is placed behind the head).

Even if you’re not an aspiring yogi or a rugby player, mild to moderate knee injuries are quite common, and it can be helpful to know which ligaments are where.

What is Lumbar Spinal Stenosis?

Stefan Voser — Wed, 15 Jul 2026 13:05:44 GMT

Stenosis comes from a Greek word that means "narrowing." Lumbar Spinal Stenosis refers to a condition when the spinal canal and/or neuroforaminal become narrow and compress the spinal cord and/or nerve roots. Compression of the cord/nerves causes inflammation and pain.

If you feel pain in your lower back which makes it difficult to walk any distance or find that you need to lean forward to relieve pressure on your lower back, particularly if this is accompanied by pain or numbness in your legs, calves, or buttocks, then you may want to visit your doctor, as these are symptoms which can lead to Lumbar Spinal Stenosis.

What causes Lumbar Spinal Stenosis?

Lumbar Spinal Stenosis is usually a result of degenerative disease or injury in the spine. The most common cause is osteoarthritis (i.e., spondylosis), a condition in which cartilage that cushions joints starts to degenerate. Osteoarthritis mostly affects people who are typically age 50 or older. Some patients are genetically disposed to development of spinal stenosis as they may have someone who has osteoarthritis in their family. In addition to that, women have a higher risk of developing spinal stenosis than men, according to the National Center of Biotechnology Information (NCBI).

To diagnose Lumbar Spinal Stenosis, your doctor may do a full physical exam, as well as asking you about your symptoms and the pain you feel. The doctor may also order imaging tests such as X-Rays, CT and/or MRI scans, or other studies such as a bone scan, myelogram, or Electromyofgraphy (EMG). For patients with a history of and physical examination findings consistent with degenerative lumbar spinal stenosis, MRI is recommended as the most appropriate noninvasive test to confirm the presence of anatomic narrowing of the spinal canal or nerve root impingement. Furthermore, artificial intelligence can be also used to manage the diagnosis, prognosis, and outcome prediction of spinal disease.

Current and Potential Future Treatments

Arthritis or nerve specialists, surgeons, and physical therapists are among those healthcare professionals that can help you if you have Lumbar Spinal Stenosis. A common approach to treating lower back pain is doing some physical therapy-type exercises to strengthen your back, stomach, and leg muscles. A doctor may also prescribe some medicines that could relieve pain and swelling. In extreme cases, steroid injections into the spine could be recommended; however, steroid injections don't work for everyone. One risk of repeated steroid injections is that they can weaken nearby bones and connective tissue, so you can only get these injections a few times a year.

There are also some alternative treatments like massage therapy, acupuncture, cranial-sacral therapy, and chiropractic adjustments that could help you cope with the pain caused by the lumbar spinal stenosis.

Most patients with spinal stenosis respond well to nonsurgical treatments and do not require surgery. However, if other prescribed treatments have not helped or you are disabled by your symptoms, your doctor may give you a surgical recommendation. The surgery is performed to reduce the pressure on the neural structures by providing more room for the spinal cord, cauda equina, and/or nerve roots.

Currently, clinical trials are underway to test the use of stem cells to treat degenerative spinal disease, an approach that is sometimes called regenerative medicine.

Understanding Meniscus Tears, One of the Most Common Types of Knee Injuries

Stefan Voser — Tue, 14 Jul 2026 12:20:42 GMT

Have you ever imagined what would happen if you could not do routine tasks like walking up and down stairs, jogging, running, hiking, kneeling and other activities because of the pain you have in your knee?

Although we may not pay a lot of attention to our knees, they play a very important role. This plain hinge joint allows your legs to support your full body weight and enables you to make all kind of movements, like twisting and turning. The knee is the one of the largest joints in the human body, and it is also the most complex and vulnerable to being injured.

Anatomy of the Knee

How much do you know about the knee? Here’s a brief anatomy lesson.

The knee consists of some primary parts. First, there are the four bones: the femur or thigh bone, patella or kneecap, tibia or shinbone, and fibula or calf bone. The knee joint is formed where the thigh bone, kneecap and shinbone meet. Ligaments make up the next part of the knee. Ligaments join the knee bones and help to provide stability to the knee. Tendons, the third part of the knee joint, connect the bones of the knee to the leg muscles so that the knee joint can move. Muscles help to stabilize, extend and flex the knee joint. Lastly, there is cartilage. There are two types of cartilage found in the knee. Articular cartilage, which is located within the knee, coats the end of the bones in the knee joint to ensure the smooth gliding surface to the bones. Between your thighbone and shinbone, there is second type of cartilage called menisci, individually called meniscus, that provides a cushion (C-shaped) and joint stabilizer between the weight-bearing bone surfaces in the knee. Although the meniscus is tough and flexible, it is relatively easy to damage. The meniscus has blood supply in the periphery (about 30 percent of the substance), and because of this, a damaged meniscus could be healed if the injury hits somewhere in the blood flow zone.

Meniscus Tear

There are some common findings in patients with knee pain, and one of them is called a meniscus tear. It can happen when someone makes a sudden movement, like twisting or turning the upper leg while the foot is planted and the knee is bent. These kinds of risky movements that put strain on the knee are mostly done by athletes engaged in sport activities like football, volleyball, baseball and skiing; therefore, athletes involved in these kinds of sport activities are at higher risk for meniscus tears. Older individuals are also at an increased risk, irrespective of activity level. According to a study published in the New England Journal of Medicine (NEJM), the risk of incurring a meniscus tear increase with increasing age as the result of the natural course of meniscal degeneration.

Diagnosing Meniscus Tears

Common symptoms of meniscal tears include pain, swelling, and the feeling that your knee cannot support you anymore or cannot be moved. If left untreated, these symptoms will eventually lead you to see the doctor. Your doctor will examine your knee and may perform several tests to evaluate the meniscal tear. After that, radiological imaging may be ordered to double check or confirm the result of the physical examination. Magnetic resonance imaging (MRI) provides an accurate and less invasive way to detect meniscus tears and may avoid the surgical risks of arthroscopy, another way to diagnose meniscus tears. By utilizing the energy from radio waves and a strong magnetic field to provide detailed images of both hard and soft tissue within the knee, MRI gives a good picture of the size of a meniscus tear and detects where it is located. Thanks to new techniques, MRI could enable full knee exams to be performed in 5-10 minutes.

Since fast but accurate interpretation is expected and important, radiologists may use machine learning and deep learning, subcategories of artificial intelligence (AI), to cope efficiently with image analysis.

Lumbar Spinal Stenosis

Stefan Voser — Tue, 14 Jul 2026 12:08:17 GMT

They say that you don’t appreciate what you’ve got until it’s gone, and this is certainly true when it comes to the human body. Aging causes atrophy and loss of elasticity of many systemic tissues ranging from those that make up the lenses of our eyes, to arteries of our hearts, to the frontal cortex of our brains. The muscles, tendons and ligaments that hold our frames together are no exception.

However, there is one important tissue of the musculoskeletal system that many people rarely think about: cartilage. There are three types of cartilage:

Elastic cartilage - a springy type of cartilage that gives shape to our ears and the tips of our noses
Hyaline cartilage - a springy, tough, and elastic cartilage found around the windpipe and between the ribs and joints
Fibrocartilage - the toughest type of cartilage, found between the bones of the hip and pelvis as well as between the discs and vertebrae of the spine

It is this third type of cartilage, or rather the lack of it, that is so often the cause of chronic back pain, especially in older adults. Age-related changes to cartilage and related tissues can result in the following:

Degenerative disc disease: Just as the pillows in our beds get more compressed with usage over time, the discs of our spine can become brittle and flattened. Discs may bulge out or vertebrae may no longer sit properly on top of each other, both of which can also cause compression on the spinal cord.
Ligament thickening: Our spinal ligaments can ossify (turn from ligament to bone). This can lead to a narrowing of the space between the vertebrae and spinal cord.
Spinal osteoarthritis: The fibrocartilage that covers the facet joints (which connect the backs of the adjacent vertebrae) can become inflamed and degenerate. When this happens, sometimes the impinged vertebrae can form bone spurs in the body’s attempt to repair itself. Bone spurs, or osteophytes, are tiny, pointed outgrowths of bones. Although they are not painful in and of themselves, they can irritate or grow into the space around the spinal cord. Sometimes a compression of the spinal nerves results.

All of these conditions can result in spinal stenosis, a narrowing of the space in the spinal canal. According to the National Center for Biotechnology Information database, acquired lumbar spinal stenosis is a “significant cause of disability in the elderly” with a prevalence of 19.4% for populations aged between 60-69 years of age. It is also the most common cause of spinal surgery in patients over 65 years old.

Classic symptoms of lumbar spinal stenosis include pain exacerbated by prolonged walking or standing, numbness, tingling, and muscle weakness. Although most cases of spinal stenosis tend to have a gradual onset, severe cases, typically injury-induced, can result in loss of motor function in the legs. The most extreme instance of lumbar spinal stenosis, the rarely occurring cauda equina syndrome, can result in loss of control of bladder and bowels and require immediate surgery.

Because any prolonged pressure on spinal nerves can result in crippling pain and possible permanent damage, it is vital for clinicians to accurately diagnose and treat spinal stenosis. Non-contrast MRI is most commonly used to determine the extent of the narrowing of space in the spinal canal.

There are lots of things that disappear as we age. In the case of lumbar spinal stenosis, that missing thing is empty space.