Meniscus Tear of the Knee Joint

Knees are among the hardest-working joints in the body. They bear our weight, allow us to walk, run, jump and twist smoothly. Within the joint are two C-shaped soft tissue structures called the ‘menisci’, which act somewhat similar to shock absorbers between the thigh bone (femur) and shin bone (tibia). When a meniscus is torn, it can lead to pain, swelling, and loss of normal functions, significantly impacting activities of daily living and athletic performance.

Let’s try to understand everything about meniscus tears: what they are, how they happen, signs to watch out for, and the best ways to treat them.

What is a Meniscus?

Meniscus in the knee joint is a specialized, crescent-shaped piece of fibrocartilage that plays a vital role in joint function and stability. They are located between the femur (thigh bone) and the tibia (shin bone). There are two menisci in each knee:

• Medial meniscus: located on the inner part of the knee.

• Lateral meniscus: located on the outer part of the knee.

  
  

The menisci are crucial for normal functioning of the joint because they play a vital role in evenly distributing the body weight across the knee joint, provide stability, and protect the cartilage from wear and tear. When a meniscus gets torn, the smooth function of knee is disrupted, leading to symptoms like pain, catching, locking, or giving way.

What are different parts and zones of a meniscus?

Each meniscus is a C-shaped structure divided into 5 parts:

Anterior Root, Anterior Horn, Body, Posterior Horn and Posterior Root.

Roots, as the name suggests, are where the meniscus is anchored to the bone. Meniscus is attached to the joint capsule at the periphery and has a free edge inside. Pressure exerted by the thigh bone on the knee joint during standing, walking, jumping is evenly distributed by the meniscus throughout the joint in the form of ‘hoop stresses’.

Meniscus receives its blood supply from periphery i.e. capsular side, hence the is divided into three zones:

1. Red-Red Zone: it is the most peripheral part, which has a rich blood supply & hence a good healing potential

2. Red-White Zone: it is the middle part, which has somewhat poor blood supply & hence the chances of healing are slightly less

3. White-White Zone: It is the innermost zone, and because it does not have a vascular supply, it has no potential to heal even if repaired.

How does a meniscus tear occur?

It can happen in any active individual, but certain activities and risk factors increase the likelihood. Common causes are:

• Twisting movements: Sudden twisting of the knee, especially when the foot is planted on the ground and the knee is bent

• Lifting weights, jumping, sudden deceleration while running

• Sports Injuries: Contact sports like football, basketball and sports requiring pivoting activities (change of direction), such as badminton, skiing

• Degeneration: In older individuals, the quality of the meniscus weakens over time, making it more prone to tears with minor injuries or even with normal activities.

What are different types of tears?

The nature of the tear often dictates the treatment plan. Some common morphological types include:

• Longitudinal tear: tear parallel to the long axis of meniscus, exiting either on superior or inferior surface or both

• Radial tear: Starts from the inner edge and propagates towards the periphery

• Horizontal tear: Split in the meniscus horizontally forming a cleavage and rarely a parameniscal cyst near the periphery

• Bucket-handle tears: It’s a large longitudinal tear, in which the inner fragment often flips into the intercondylar notch leading to locking of the joint

• Flap tears: Part of the torn meniscus becomes unstable and leads to sudden ‘catch’

• Complex tears are morphologically irregular, comprised of a combination of 2-3 tear types, and usually not amenable to repair.

What are the symptoms?

Usual presenting history is a twist of the knee associated with hearing a popping sound followed by sudden onset of pain and eventual swelling over the knee. In older individuals, tears are a result of an overuse rather a single traumatic episode.

Symptoms can vary depending on the severity and type of tear. The common ones include:

• Pain: especially while getting up from sitting position, walking, stair climbing, squatting

• Swelling: typically develops in the first 24 to 48 hours and gradually disappears over next few weeks

• Restricted movements: a bucket handle tear can present as a flexion deformity i.e. inability to completely straighten the knee

• Catching or Locking sensation: feeling of knee getting stuck in certain position.

• Instability: A sensation of knee ‘giving way’ or buckling

How is it diagnosed?

Diagnosis is made by corroborating clinical and radiological findings:

• Physical Examination:

  • Joint line tenderness is one of the easiest and most sensitive tests, although it is not very specific. It can be performed even in acute settings.

  • Special tests like the McMurray test or Thessaly test can be performed in chronic cases but they are provocative tests and hence can cause significant pain to the patient

• Imaging:

  • X-rays are first line of investigation and help to rule out bony fractures

  • MRI (Magnetic Resonance Imaging) is the gold standard for visualizing meniscus tears, their pattern, extent, grade and associated soft tissue injuries. In chronic cases, it helps to confirm the grade of cartilage wear and arthritis.

What is the prognosis of a meniscus tear? What happens if it is left untreated?

 A meniscus tear disturbs normal biomechanics of knee joint. As weight bearing and other activities continue, dysfunctional meniscus fails to distribute the load evenly across the joint. This leads to increased contact pressures over the articulating surfaces of the bones and early wear off of the protective cartilage. Eventual result is early arthritis of the knee joint. Once the arthritis starts to set in, it is more difficult to manage it, especially in younger age group.

How is a meniscus tear treated?

There is no single treatment modality which can suit every patient. It needs to be customised based on various factors. Patient related factors include age, weight, alignment of the leg, time since injury, activity level and functional demands. Tear related factors include size, location, type of tear, associated ligamentous or cartilage injuries, grade of arthritis in the joint.

A)   Non-Surgical Treatment:

Conservative management is typically preferred in older individuals with low functional demands, those who have advanced arthritis in the joint and those who are unfit for a surgery due to other health issues. In absence of these factors, acute small (<5mm) tears, especially in the periphery (red-red zone) deserve a chance of conservative trial.

Treatment strategy includes:

• Rest: avoiding activities that aggravate the pain

• Ice: applying ice packs to reduce inflammation

• Compression: Using an elastic crepe bandage or knee cap to limit the swelling

• Elevation: Keeping the leg raised

• Physical Therapy: started once the acute pain is in control. It involves exercises to regain the joint movements and strengthen the muscles around the knee.

B)    Surgical Treatment:

Surgery is indicated at the earliest in:

• Locked knee / inability to fully bend or straighten the knee

• Repetitive feeling of sudden catching

• Bucket handle tear with inner fragment flipped into the notch

• Persistent pinpoint joint line pain

In today’s world, all meniscal problems can be efficiently dealt with by arthroscopic (key-hole) surgery.

Surgical options include:

1. Partial Meniscectomy: Removal of the damaged part of the meniscus. It mainly relieves the mechanical symptoms but fails to restore the native meniscus function and joint biomechanics. It is a preferred choice in tears that are beyond repair or won’t heal even if repaired, e.g. complex tears, degenerative tears, tears in the white-white zone.

2. Meniscus Repair: This is the most preferred and feasible option in most of the tears. It involves suturing the torn meniscus with high-strength sutures. Various minimally invasive methods can be utilised to achieve a stable repair and predictable healing.

Meniscus repair surgery is only half job done as it requires its own time to heal post-surgery. Rehabilitation is longer compared to a meniscectomy. Supervised physiotherapy is the key to a successful outcome.

3. Meniscus Allograft Transplant: In rare cases where most of the meniscus has been lost or removed in a younger patient, a meniscus allograft can be procured from a soft tissue bank and transplanted into patient’s joint. It involves certain additional risks such as graft rejection and is quite an expensive option.

What is the recovery timeline post-surgery?

• Meniscectomy: Patient is allowed to walk full-weight bearing from the next day. It usually takes 4 to 6 weeks to get back to the daily routine. Physiotherapy and exercises help in quicker recovery.

• Meniscus Repair: Although it varies with the type of tear and stability of the repair, patient needs to be completely non-weight bearing for initial 4-6 weeks. It takes roughly 8 to 12 weeks to get back to routine activities. Return to sports is typically at 6 to 9 months. A well-structured supervised rehabilitation program is essential for a complete recovery and successful return to sports.

How to prevent meniscus tears?

Although it is difficult to control the natural degeneration process of the joint, risk of sustaining acute tears can be reduced.

• Strengthening the muscles of hip, thigh & knee; especially the quadriceps & hamstrings.

• Following the right technique during sporting activities

• Wearing appropriate footwear

• Warming up and stretching before playing sports or exercising

• Avoiding sudden twisting movements

• Not ignoring a dull aching pain in the knee till it blows out of proportion

To summarise..

A meniscus tear can be a frustrating and painful injury, but with the right diagnosis and timely treatment, most patients achieve a complete recovery.

Early intervention is the key. Ignoring symptoms can lead to more severe damage and a longer recovery period.

If you're experiencing knee pain, instability or locking, don't wait! Consulting an orthopaedic surgeon on time can get you back to the activities you love faster.

Your knees are designed to move. Help them keep you healthy!

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