Case 1. Adult Anterior Knee Pain (AKP) – acute overuse. The Index Case

My approach to the investigation and management of Anterior Knee Pain changed drastically in 1990, as a result of a moment of insight during the arthroscopy of a very fit paratrooper who had developed this symptom complex when he drastically increased the intensity of his triathlon training several months before.

He was going to be released from the armed forces because of this pain. Among the fittest I have ever seen, he was training with the goal of winning the competition to be the fittest in the Canadian armed forces - at that time, an annual contest.  He had vastly increased his training intensity as he started to prepare. This pain appeared after a couple of weeks - and it just didn't go away. It was several months down the road after this pain had begun that I saw him in my office. As part of his release processing, my role as the head of orthopaedics was to verify diagnoses and intervene where possible. 

When I examined him everything was completely normal in the knee except for one positive physical finding - when I pushed on his knee just below the patella with my thumbs and extended the knee as I was holding the leg this elicited substantial pain about his patella. This observation is now called the 'Hoffa's Test', and it is the only reliable confirmatory finding on the physical exam for AKP.

In those days Anterior Knee Pain was not something that we were traditionally able to cure or particularly help. Seldom were the symptoms made much better by the operations we were doing in the '80s and early '90s - and sometimes we made things worse.

I call this the 'Index Case' because of what happened in his arthroscopy, and the immediate disappearance of his pain on simply removing the infrapatellar plica.


Surgical Findings

At arthroscopy I found that the knee was pristine, but there was a small zone of inflamed synovium adjacent to the bony attachment point of a normal-appearing but rope-like infrapatellar plica, a structure that was considered at that time to be an embryological remnant of no mechanical, nutritional, or clinical importance. It was common practice at that time to simply remove it because it was in the way of examining the other structures in the knee.

What triggered my attention during the arthroscopy was that the infrapatellar plica, sitting right beside this area of inflammation, showed subtle changing tension with knee motion. This observation, a form of "Eureka moment", focused my attention, suggesting that the structure had an actual mechanical function.

I surgically released the infrapatellar plica  at its femoral attachment, and removed any fibrous remnants of the structure.

The patient had rapid and permanent pain relief.


So what had I done that interrupted this man's pain?

With the remarkable result, I began scoping patients with this recalcitrant problem and resecting any infrapatellar plica, and confirmed that most were relieved of their pain. In the many years that followed we undertook research that established the concepts that I now present in this course.