Anatomy of the Knee


The knee joint is taken for granted by most people at least, that is, until injury occurs. It is the largest of all of the joints in the body but, because of its complex anatomical structure, is highly susceptible to injury.

Some 200,000 knee injuries per annum in the USA alone involve the anterior cruciate ligament (ACL) with non-contact mechanisms being the primary source. ACL injuries are devastating as they render the knee unstable. Further, females are 2 to 8 times more likely than males to suffer an ACL injury. Understanding the anatomy of the knee is therefore critical in determining how and why these injuries occur and what can be done to prevent them.

Women should also read the section here on preventing knee injuries as this gives them some immediate focus exercises to prevent this dreadful injury occurring.

Here’s a diagram of the knee that explains what and where the various ligaments are:

Anatomy of the Knee

Anatomy of the Knee

ACL = Anterior Cruciate Ligament (this has gone on me)

MCL = Medial Collateral Ligmanet (also gone) – this is on the inside of my right knee

LCL = Lateral Collateral Ligament (also gone – outside of my right knee)

PCL = Posterior Cruciate Ligament (this is the good news, it’s OK on me)

The stability of the knee largely depends on these four major knee ligaments (the tough, elastic tissues that hold two or more bones together.)

The MCL and LCL have sufficient blood flow to heal themselves when torn. The ACL and PCL form a cross within the center of the knee and are constantly bathed by the synovial fluid. They have little blood flow and failure of either is extremely serious in that a) that will render the knee completely unstable, b) expensive reconstructive surgery will likely be required to repair the tear and c) between 6-12 months of post surgery rehabilitation will be required to yield a full strength, working knee. Fortunately, the PCL is much stronger than the ACL and consequently much less likely to tear.

Day 3

For me, it’s MRI day where I get confirmation on the early diagnosis that my ACL, MCL and LCL are all torn with the PCL intact.

I’m still unable to put any kind of weight on my right leg and the process of using crutches is painful on my hands and armpits. Just getting up in the morning is exhausting. Hopping into the shower and then standing on one leg is already getting to be hugely tiresome. Sleeping with my leg elevated on pillows and being unable to turn over is also proving to be a challenge. I continue trying to get the swelling down with bags of frozen peas and other improvised icing devices.

Day 5

Today I review the MRI scan with Dr McCarty. The swelling is still awful but I’m hoping he can sneak me into surgery over the next few days and I can start on the road to recovery.

I’ve been very positive so far but today was a setback. The early diagnosis is confirmed but Dr McCarty wants my MCL to heal before surgery such that I have better range of motion. He also said that he can’t operate with so much swelling on my knee. Surgery is set for 3 to 4 weeks hence assuming I make good progress in physio in the meantime. I’ve booked a course of pre-surgery physio at the Boulder Center for Sports Medicine starting in a week and running twice a week with a focus on range of motion and reduction in swelling. I’m to check in again with Dr McCarty in 10 days or so where he’ll further assess my preparedness for surgery.

One good thing to come out of today was the replacement of my lightweight knee brace with a seriously neat DonJoy TROM Adjuster Knee Brace. This is a great device that I hope will give me the strength and confidence to move from hopping on my crutches to some semblance of walking. Also, I now have an Aircast cooling system to take the swelling out of my knee. This allows me to compress and ice at the same time and is something I would highly recommend for anybody suffering an ACL injury or equivalent.

Of course I’m still taking some ridiculously strong painkillers which keeps the pain down and the best advice I’ve received so far is not to let the pain get ahead of you. That means taking the painkillers before the pain resurfaces and, if necessary, setting your alarm for the middle of the night to take your next dose. This has ensured that I have been largely pain free since my ACL injury if not somewhat uncomfortable and inconvenienced!