Meniscus Tear

General Anatomy of the Knee

The knee is an important weight-bearing joint of the body and allows us to walk, run, jump and squat. The knee is composed of 4 bones: femur, tibia, fibula, and the patella. The knee has 2 main articulations: one between the femur and tibia and the other between the patella and the femur. The knee is encapsulated by a joint capsule filled with synovial fluid that lubricates the joint. Within the knee there are other structures to help give the joint stability such as ligaments, menisci, fatty deposits, bursas and articular cartilage. There are also muscles, fascia and connective tissue that surround the knee to aid in the stability of the joint.

There are 2 menisci located in the knee – the medial meniscus and lateral meniscus. These c-shaped structures help support the knee joint and cushion the femur on the tibia.

Meniscus Injury

An injury to the meniscus can happen when twisting or rotating the knee, such as pivoting or sudden stopping and turning. Other activities such as deep squats or lifting heavy items can also cause the meniscus to tear. Traumatic meniscus injuries are common in athletes that play contact sports such as football and hockey. As people get older, people may suffer from degenerative meniscus tears. Degenerative tears happen because the tissue of the meniscus starts to gradually wear out, making it more prone to injury. Therefore, the meniscus can tear with little or no trauma with activities such as walking or climbing stairs.

Risk factors:

  • Age
  • Performing activities that involve twisting and pivoting
  • Participating in contact sports
  • Overuse
  • Alignment of the knee
  • Overweight

Common Symptoms

  • Pain
  • Giving way/locking of the knee
  • Loss in range of motion including blocking/jamming
  • Difficulty with weight-bearing
  • Swelling

IS DIAGNOSTIC IMAGING USEFUL?

Diagnosis of a meniscus injury can be made by combination of patient history, physical examination, and diagnostic imaging.   The most accurate diagnostic test is MRI.

  • X-ray – can only see bones and joints.   Therefore, useful to rule out any osteoarthritis,  fractures, and dislocations. Cannot diagnose meniscal injuries.
  • Ultrasound – can be used as a screening test but resolution not sufficient to see extent of meniscus tear.
  • MRI – provides high definition imaging to visualize soft tissue structures such as the meniscus. Used to confirm where the tear is and how severe.


Prognosis

Although in theory, the location, type, and severity of tear shall determine outcome, but unfortunately,   because most meniscus tears are at the back portion (posterior) of knee, the torn meniscus is jammed or “sandwiched” in the knee joint by the femur and the tibia.  This causes pain particularly in standing and bending.    In small proportion of sufferers, the tear can be managed by conservative management but for many,   the torn piece has to be removed by arthroscopic surgery, where the surgeon would “clean” the knee joint using video camera and surgical instruments through small holes.     Most patients are discharged home the same day and where indicated,  are referred for physiotherapy for post-op rehabilitation.