Biomechanics, Evaluation and Osteopathic Perspectives of the Knee

00:00 You. We're going to talk about the knees.

00:02 Knees are an interesting joint, part of the lower extremity, and difficult to manipulate because you don't have lots of tools in your armamentarium.

00:13 But what you do have is a lot of patients who have problems.

00:16 So understanding the biomechanics, understanding the history, and witnessing and predicting what's going to happen to the knee is often all you can do.

00:27 So we're going to talk about the knee itself, what makes it up and what we can do and where we can focus.

00:34 So, starting with the anatomy. The knee is an interesting joint.

00:38 It's basically the femur with two grooves with the patella in between, with a whole bunch of articulations held together by ligaments, bursa, and muscles.

00:48 When you look at the articulation, it's a hinge joint.

00:51 You have the tibiofemoral articulation, patellofemoral articulation, and the tibiofibular articulation.

01:02 And the tibia and the fibula are interesting bones.

01:05 Tibia is the flat one anteriorly, and the fibula is the lateral bone that we used to say was only for muscular attachment.

01:15 We're not sure fully what the fibula's role is, but we do know it does help with some of the motion, some of the gliding of the knee, and it's important.

01:26 We're going to talk a lot about the menisci, the medial and lateral meniscai.

01:31 Those are the shock absorbers of the knee.

01:33 Those are the pads that displace the energy so that when you're walking, your pain is not going to be pinched, your pressure is not going to be focused.

01:43 It's going to be splayed, displaced, and allow you to use your whole knee and your whole foot area.

01:49 And we'll discuss the bursa, the bursae little pockets that have synovial fluid in it that will swell with overuse and give you a sense of what's going on.

01:59 So take a look at the picture here, get a sense of the anatomy, use your own body as a model and work on understanding the bones, the muscles and the ligaments that are going to explain where you're going to have problems.

02:13 Again, the bones are easy.

02:16 You have the femur superiorly, you have the tibia, which is the flat bone, and the patella, which is a sesamoid bone.

02:25 It's a bone within the ligament.

02:26 And the fibula, which comes down on the lateral aspect of the leg.

02:32 The muscles and fascia are there.

02:35 The quadriceps are the ones you're going to be focusing on the most, the ones that are going to extend the knee and the quadriceps, vastus, medialis, lateralis, and intermedius, as well as the rectus femoris.

02:52 So the muscle and fascia are important.

02:55 You have both flexors and extensors. You have the quadriceps and the hamstrings in the back causing the flexion.

03:03 And then we'll talk about the ligaments, the anterior cruciate and posterior cruciate ligaments that keep the knee stable, and the medial collateral and lateral collateral that also keep the knee in place.

03:16 So those are the four ligaments we'll talk about that are often injured and need to be paid attention to and often tested for.

03:23 In terms of the joints within the articular capsule, you have the tibiofemoral joint and the patellofemoral joint that are going to help with the hinge motion.

03:35 And you have the superior fibulotibial joint and the knee as well.

03:40 It is a modified hinge joint.

03:43 There is flexion and extension of the knee.

03:45 When there is instability, you're going to have more motion to the sides, which we try and restrict.

03:52 There's some rotation possible, as you notice when you go side to side.

03:57 You'll notice you do get some rotation of the knee, and you're going to have more rotation when it's flexed, which is also when you're more likely to injure the knee because of the laxness of the muscles and the loss of protection.

04:11 The meniscai again allows for stability of the joint.

04:17 They deepen the tibial plateau.

04:19 They give you a substance that will displace energy and force when you're walking.

04:26 It will allow for a smoothness of functioning by decreasing friction.

04:30 It increases the contact area for the femur and absorbs shock.

04:36 When we talk about the medial and lateral menisci.

04:39 We also note how much vascularity it has in each portion, separating into the anterior, middle, and posterior portions of the menisci.

04:49 And the more blood supply you have, the more likely the menisci can heal on their own.

04:57 If you don't have much blood supply and you do injure it, it's going to be a tough injury, and it's not going to be something that's going to heal quickly or easily on its own.

05:07 And often surgical intervention is suggested.

05:10 If you do remove the menisci because of injury or trauma, it doesn't stop you from having normal function, but it does limit the amount of time you can have normal function and increases the likelihood or possibility of having swelling or other abnormalities occur from use of the knees.

05:30 It will also lead to an increased wear and tear on the articular surfaces and increase the risk of developing degenerative joint disease later on in life.

05:40 So the patella is the largest sesamoid bone in the body.

05:44 It floats in the quadriceps tendon, and the quadriceps are the four muscles that will extend the knee.

05:54 The patella will slide vertically along the ridges of the femoral condyles and it does have an articulation. So it's a fulcrum, it helps with motion, it helps with stability, and it gives you the strength to move the leg harder and stronger.

06:13 It does also allow other motions and patellar moves side to side and gives you some freedom.

06:20 The ligaments. There are four ligaments holding the knee together.

06:23 The anterior cruciate ligament, which will prevent anterior displacement of the tibia and prevents hyperextension of the knee.

06:32 Occasionally you see people who will extend greater than 180 degrees.

06:36 There is some ligamentous laxity on occasion and that can occur, but the anterior cruciate ligament keeps it strong, keeps it stable and prevents overextension and stabilizes the knee.

06:50 The posterior cruciate ligament will prevent posterior displacement of the tibia and hyperflexion of the knee.

06:58 The medial collateral are the deep fibers that are attached to the medial meniscus and keep the knee stabilized.

07:05 And the lateral collateral does not attach the lateral meniscus, but it attaches to the fibula, so it does bring the fibula into motion.

07:15 Why are we talking about ligaments and muscles in an osteopathic medicine lecture? Because people will complain of pain, people have trouble functioning, and it's important to know when to use flexion, when to use extension, and how you use knee motion to both affect one joint above the hip and one joint below the ankle.

07:35 So those are important concepts.

07:37 Bursae are the little pockets with synovial fluid.

07:42 They have serous membranes that will secrete a lubricating fluid that eases motion.

07:49 They're found in locations where you have friction and motion.

07:53 They swell up with more use, they shrink up with less use, and it allows the structures in the nay to move freely.

08:01 And it's also a warning sign when you overuse a joint or misuse a joint.

08:06 If you have an unstable or a deviated knee, the bursa in that area will swell up.

08:13 You will also have increased bony deposition in areas of greater friction.

08:18 Wolff's Law, where pressure is going to increase bony formation, is affected by the bursa.

08:23 The bursa gives you a little bit of leeway in that you're not always having the bone on bone friction causing bony growth.

08:32 You're having some bursa, some fluid, some area of separation.

08:38 When you walk the bursa will also affect limitations of motion, and it's important to know that what's possible.

08:47 When you're walking, you need to be able to move the knee about zero to 60 to 70 degrees.

08:52 When you're climbing stairs, you need to be able to get to 80 degrees of motion of the knee to get upstairs.

08:59 When you're going downstairs, you need to get to 90 degrees of motion.

09:05 sitting down, you want to be able to flex the knee a little bit past 90.

09:10 So, 90 to 95 is usually going to be comfortable sitting on a chair or on a couch.

09:17 In order to tie your shoe, you need to be able to flex it to 100 to 110 degrees.

09:23 That's why a lot of people will lose the ability to tie a shoe before they lose the ability to walk up or downstairs or have trouble sitting.

09:32 And lifting objects often takes greater flexion up to 120 degrees.

09:40 So you're going to lose the ability to lift objects comfortably and you're going to be off balance, lifting objects, using other muscles and pulling the skeleton in other ways in order to stabilize yourself, using a wider gait, using your arms and starting to develop different centers of gravity.

10:01 So even though this is the knee that's having the limitation, it affects the functioning of the whole body.

10:08 In assessing the knee, you always look at the tibia and femur in relation to each other.

10:15 So tibial dysfunctions are actually pretty common, tough to treat, and people usually don't think of this as an osteopathic issue.

10:24 They think of it as an orthopedic issue and a bony issue.

10:28 The dysfunctions that we treat osteopathically are typically distal tibia and distal fibula, not the proximal.

10:37 A tibial dysfunction can be when you have the tibia abducted or adducted, whether it goes anterior or posterior.

10:45 Again, the tibial dysfunctions we can treat are going to be the distal ones, and it's usually accessed by sliding the tibia laterally, pushing it out away from the body or medially and anteriorly.

11:02 Typically, I push it more laterally and treat the tibia that way.

11:08 In terms of the fibular dysfunction, you can have anterior or posterior fibular head, and that's the distal fibular head close to the ankle, and it's usually assessed by sliding the fibula anteriorly or posteriorly.