Diagnosis: Knee Banger Part 1 (The What?!)

Our first in depth analysis of a member’s question is in regards to a recent traumatic injury to his knee.  He fell and banged his knee two days ago and now it hurts to walk.  The puzzle begins in my mind.

The worst case scenerio is that there is a fracture that can be confirmed through a x-ray. The Knee Ottawa Rule helps me determine if this needs urgent medical attention or if this is something I can fiddle around with and manage at the clinic.  X-Ray is advised if he presents with ONE of the following: 1) over 55 years of age 2) tenderness over the fibula head 3) isolated tenderness to the knee cap (patella) 4) inability to take more then 4 steps 5) limited knee bending (flexion) past 90 degrees.  Take note that the amount of pain, swelling and/or bruising does not matter in this case.  He confirms that there is no suspicion for fracture.  Phew!  A fracture will slow him down for at least six to eight weeks.

If I was to breakdown how he fell, it sounds like a compressive impact of his knee, especially the knee cap, to the ground.  The knee cap, also known as the patellofemoral joint, functions like a pulley system.  A pulley consists of a circular shaped object with a groove design around the edge that allows a rope to sit in it.  The front thigh muscle, quadriceps, and the tendon below the patella is the rope.  The patella is the pulley with actual groove like surface.  When a pulley has too much tension on it, the rope will dig into the groove and be slow to glide called causing friction.

Where am I going with this?  There is a special test that mimics the compressive force of the fall called the McConnell test.  You push your patella firmly (the tension) into your knee when it is bent at varying angles.  Let’s use 90 degrees since it’s close to the knee angle of our club member when he fell.  This will be painful or uncomfortable.  If not, contract your quadriceps by stiffening that muscle and this tends to replicate the pain with sitting or walking.  In reality, it’s not the patellofemoral joint and its cartilage that is causing the pain but the supporting ligaments and tissue that is irritated.

There is one more structure I am curious to know about.  It is called the bursa.  I am not talking about the large city in Turkey (you like the quick geography lesson ?) but the fluid filled sac located throughout our body.  There are a few of them within the knee, but the one that I am interested in is located right under the patella tendon called the infra patella and pre patellar bursa.  Imagine a water balloon made out of a material that can be tossed around and not break so easily.  The water property helps it resist forces at high impact and pliable at low impact or tension.  The bendable nature of the bursa helps with reducing friction and complement the pulley patella system.

The impact of a fall can be too much and it irritates the bursa.  There is no special test besides poking and pushing to test if it is the pain source.  The reason I bring it up is that it is important in managing the pain, which will be the next part of this series.  A low sustained force, like prolonged kneeling, can irritate the bursa.  This is often called “plumber’s knee” or “housewife’s knee”.

I hope this article allows you to determine what is going on to the knee when there is a compressive “knee banger” injury.  Stay tuned to part two where I explain how to self treat and reVITALize yourself from a fall onto your knee.  In the meantime, ice and avoid keeping the knee in prolonged position like sitting is advisable.  Keep the stunts to the professionals everyone.