Knee joint and related structures

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Applied Anatomy

Meniscal tears

The medial meniscus is more commonly torn because it is less mobiile.

  • Peripheral tears bleed- red tears
  • Central tears don't bleed- white tears

Cruciate Ligament injuries

  • Anterior cruciate more commonly affected as its more fixed

Collateral ligament sprains or ruptures

  • Occur because of forced twisting: Abduction or adduction

Arthritis of the knee joint


  • Osteoarthritis, septic arthritis, synovitis,


  • Clergyman's knee - infrapatella bursa
  • Housemaids knee - pre patella bursa

Unhappy triad

This simultaneous tear of three structures attached to each other:

•  Medial meniscus

•  Anterior cruciate ligament

•  Tibial collateral ligament

It is a common injury among footballers, and occurs during forceful abduction and lateral rotation of the leg. These movements cause excessive tension on the medial aspect of the knee.


Surgical Approach

  • The knee joint is widely exposed from the front on either side of the patella by incisions through the vasti and alongside the patella and its ligaments

  • Exposure of the back of the knee joint capsule through the popliteal fossa involves opening up the interval between the tibial nerve and Semimembranosus

  • The nerves and   vessels are displaced laterally

  • The medial head of gastrocnemius is detached.

Knee aspiration

Usually carried out from the side at the upper margin of the patella, the needle entering the suprapatella bursa.


Injection into the knee

Joint is entered at the lower border of the patella on either side of the patella ligament. Care must be taken not to damage menisci or joint surfaces.



This is the examination of the knee cavity using scope. The approach is usually on the lateral side of the patella ligament.


The knee joint is clinically five joints in one. Because lesions in other joints can cause symptoms in the knee joint, and also because of its complexity, the joint can clinically be looked as made up of:

  • Medial tibio-femoral joint
  • Lateral tibio-femoral joint
  • Patellofemoral joint
  • Proximal tibio-femoral joint
  • Hip joint