Continuing on in our clinical series we will move just below the hip to discuss knee pain. The knee can be a very problematic and painful joint. This is supported by the fact that the knee is by far the most commonly replaced joint in our body, being responsible for 54.5% of all joint replacement surgeries. The hip is the next most commonly replaced joint and is responsible for 38.6% of all joint replacements.
Knee Anatomy & Function
The knee functionally is a very stable joint as it primarily moves in one plane of motion (known as the sagittal plane) with flexion (bending the knee) and extension (straightening the knee). There is minimal rotation of our knee joint to help with locking and unlocking the joint as we need it to be in a more locked position when we are standing and obviously unlocked when we are moving (walking, running). The knee is important to walking, running, and standing.
The knee joint, known scientifically as the tibiofemoral joint, connects the thigh bone (femur) to the larger of the two lower leg bones, the tibia. In addition to the tibiofemoral joint, the knee also is formed by the patellofemoral joint, which joins the kneecap, patella, to our femur.
Anatomically, the knee is well stabilized and supported by multiple ligaments some of which include the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). The ACL is one of the most commonly injured ligaments. We frequently hear about these injuries in professional sports, especially in American football. The knee also has two cushions, the medial and lateral meniscus, that help to evenly distribute pressure between the femur and the tibia.
The primary muscles of the knee include the quadriceps and hamstrings. The quadriceps are named as such as they are a group of 4 actual muscles: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. The quadriceps are located in the front of the thigh. They are the primary extensors (straighten the knee) of the knee joint. In addition, the tendon of the quadriceps is responsible for helping to maintain proper positioning of our patella (kneecap). The hamstrings are a group of 3 muscles located on the back of the thigh: the biceps femoris, semitendinosus, and semimembranosus. The quadriceps are the primary flexors (bend the knee) of the knee joint. In addition to the quadriceps and hamstrings the other muscles of the knee joint include the popliteus, gracilis, and sartorius, which assist with rotation of the knee joint.
Let’s Give Our Knees A Break (no not literally!)
The knee is arguably the most stressed joint in our body. However, there are a number of things that we can do to help decrease the overall strain to our knee throughout our lifetime. The knee is one of the most common joints in our body to develop osteoarthritis. Hence, the fact that it is the most common of all surgically replaced joints. Let’s discuss some of the factors to help with the health of our knees.
As discussed, the knee is primarily a stable joint that moves predominantly in one plane (sagittal) with flexion and extension. So being a joint that is built for stability, why do we see so much wear and tear to the knee and such a high prevalence for osteoarthritis. In determining the factors that could displace more stress to our knee, we have to look to its closest anatomical neighbors, the ankle and hip.
The ankle and the hip are both primarily mobile joints. A loss of mobility in either of these joints will likely displace more stress to the knee to compensate for the loss of mobility above or below the knee.
As we have discussed previously, loss of hip mobility is often seen today as a result of extended periods of prolonged sitting, which many of us tend to do relative to our occupations, television, and driving. Other factors that can cause loss of hip mobility include sedentary lifestyle, lack of exercise, and history of hip injury. Another factor that can cause loss of hip mobility is poor core stability, which can also be relative to prolonged sitting, sedentary lifestyle, lack of exercise, and surgery (many abdominal surgeries require a disruption to the core musculature).
Just like the hip, the ankle is also a primary mobile joint, which we have previously discussed in our joint-by-joint approach. Loss of ankle mobility will transfer more demand and stress to our knee. Common causes of loss of ankle mobility include shortening or tension in our calf muscles (gastrocnemius, soleus) or stiffening of our Achilles tendon, prior ankle injuries (such as ankle sprains), bony restrictions, and pes planus (flat feet). In addition to displacing more stress to the knee, limited ankle mobility also limits proper hip function as it has been shown to reduce activation of the gluteal muscles. So, as we can see limited ankle mobility effects the knee from the increased need for mobility compensation by the knee as well as it limits proper hip function with its affect on gluteal activation. Therefore, ankle mobility is very important to reducing stress to our knees.
Common Knee Injuries: How to Lower Our Risk
Let’s take a look at some of the most common knee injuries and how we can help reduce our relative risk to them. Understanding that again, we can never prepare or predict for injuries that are related to direct trauma. However, there are many things that we can do to help reduce are risk to injuries that are related to repetitive stress, let’s take a look.
ACL Injuries
The most well-known injury of the knee is anterior cruciate ligament (ACL) injuries. The majority (80%) of ACL injuries are non-contact injuries. Approximately 350,000 ACL repairs are performed in the US annually. Though we cannot do anything to entirely avoid the potential of an ACL injury, there are a number of things that can be done to help significantly reduce your risk to this type of injury. In fact, research shows that women can reduce their risk of ACL injury by 52% and men can reduce their risk by 85% with an ACL injury prevention program. A good ACL injury prevention program will focus on improving stability around your knee joint, especially in the frontal plane (side to side); improved resistance to muscular fatigue, improving trunk, pelvic, and hip stability (loss of stability in these regions will translate to increased stress to your knee), and maintaining symmetrical strength of the right and left lower limbs. This is done through a training program that includes plyometrics, neuromuscular and strength training, with a particular focus on building strength through unilateral (single sided) exercises.
Patellar Tendinitis
Patellar tendinitis is a commonly diagnosed condition of the knee. Technically speaking, it is a condition where the patellar tendon (which is the distal portion of the quadriceps tendon that goes over our kneecap and attaches to our lower leg bone, tibia) becomes painful most often due to repetitive stress and strain. It is commonly seen in sports that involve jumping, such as basketball and volleyball. Our best defense to reducing our risk to patellar tendinitis is to reduce the demands and stress to the knee joint with jumping. I’m sure by this point you can guess that ankle mobility will be important to reducing stress to the knee with jumping. This is related to the fact that with jumping we will preload our legs to jump by going down into a squat prior to jumping. Without adequate ankle mobility, we will place more stress to our knee to compensate for the lack of ankle mobility, which will displace for stress to our quadriceps muscle, which will become the more dominant muscle with jumping rather than our calf muscles (gastrocnemius and soleus). Jumping in this manner overtime will displace more strain to our patellar tendon and ultimately increase our risk to patellar tendinitis. Maintaining good strength in through the quadriceps and hamstring muscles will also help to unload some stress off of the patellar tendon with jumping.
Iliotibial (IT) Band Syndrome
Last week in discussing hip pain we talked about trochanteric bursitis and how that can be related to tightness of our iliotibial band (IT band, a band of connective tissue that helps with stability of our hip and knee, that runs on the outside of our thigh from the hip to the knee). Tightness of our iliotibial band can also result in a condition known as iliotibial band syndrome. As we discussed in our discussion of hip pain, tension in our iliotibial band frequently results from under activation or weakness in our gluteus medius, which is our primary hip abductor. The gluteus medius also is one of our primary lateral stabilizers of our hip (very important to allowing us to walk and run in a straight line). Without the proper ability to activate or maintain proper strength in our gluteus medius, the iliotibial band will tense to compensate for lateral stability of the hip. When tight, the iliotibial band can rub across an area of our knee known as the lateral epicondyle that can result in lateral knee pain as the IT band becomes inflamed as a result of the irritation from the rubbing against bone. The weakness of the gluteus medius and loss of lateral stability of the hip is probably the most common cause of IT band syndrome. However, there can be some structural and anatomical causes including increased Q angle (the Q angle is the angle that is created between the hip and the knee and the pelvis and the knee, typically the wider the hips the greater the q angle) and pes planus (flat feet). Iliotibial band syndrome is most commonly found in runners and cyclists.
Meniscus Injuries
Another common injury of the knee involves injuries to the meniscus. Again, the meniscus are cartilaginous structures that lie between the two surfaces (femur and tibia) of the knee. Their job is to help evenly distribute pressure throughout the knee joint and help protect the bony surfaces of the knee joint. Meniscus injuries just like ACL injuries can result from contact and non-contact injuries. Obviously, just like any other contact injury there is nothing that we can do to reduce risk to these types of injuries, so our focus is helping to reduce risk to the non-contact injuries. Since the primary role of the meniscus is to help cushion and even pressure to the joint, it would make sense that reducing unnecessary stress to our knee joint would be a sensible approach to reducing our risk of meniscus injuries. Again, maintaining good ankle mobility to reduce the need for compensation by the knee for limited ankle mobility is very important to reducing stress to the meniscus. Strong, mobile hips and good core stability to help improve stability to the knee and reduce compressive load to the knee joint is important to reduce stress. Other factors that can help to reduce the risk of meniscus injury include reducing stress to our knees through weight management and good nutrition. Supplementation with glucosamine has been widely researched to show a decrease of breakdown and degenerative changes of the meniscus.
Osteoarthritis of Knee
Another common factor that is widely seen in the knee is osteoarthritis. This can be a result of a history of a ligamentous injury (such as an ACL injury) or a meniscus injury that impacts the overall stability of the joint increasing the likelihood of degenerative changes and arthritis. Again, reducing unnecessary stress to our knee joint through maintaining good ankle mobility; strong, mobile hips, and good core stability is a great defense against osteoarthritis. Though, we can not entirely eliminate the potential for changes such as osteoarthritis, especially with age. We can certainly slow the onset or progression of these types of conditions and the possibility of these conditions becoming more debilitating or need a joint replacement. Again, weight management can be beneficial in decreasing the stress on our joints and supplementation with glucosamine has been shown to be beneficial in helping to slow the onset or progression of degenerative changes of the knee, such as osteoarthritis.
Treatment & Management of Knee Injuries
Again, just like with any joint-related injuries there are those that are related to direct or blunt trauma. Many of these injuries involve injuries to the ligaments and meniscus of the knee. It is these types of injuries (in addition to non-contact tears of the ACL and meniscus) that may require acute medical care and possibly surgery. However, most injuries of the knee can be managed very conservatively through manual therapy and tissue healing modalities. We have great success with treating and managing many injuries of the knee. Just as important, we teach our patients how to reduce the risk of knee injuries going forward through many of the strategies we have discussed within this post.
Don’t Squat…huh?
Unfortunately, far too often, many people are advised that if it hurts, don’t do it! Now temporarily this may be true and for some may be the correct advice. However, for many this type of advice becomes more self-limiting and reduces our ability to perform functional activities throughout our day making us more sedentary and increasing our risk of more problems. This could not be truer about the knee. Far too often, we are advised to not squat as it may increase stress to our knees. Squatting is a vital movement to life…it is necessary to get onto and off of the toilet!! Therefore, it is not that we should not squat, but we should understand why we are displacing more stress on our knees with our squat that is making a squat difficult or painful. In other words, squatting is not the problem, it is the way that we are squatting that is the problem. Again, poor ankle mobility, poor hip mobility, and poor core stability will all limit our ability to properly squat and displace more stress to our knees. I would agree squatting in this manner should be avoided, however we need to correct the deficiency(s) and improve our ability to squat so that we can continue to perform this movement in a safe and effective manner to reduce stress to our knees. Life is more enjoyable when we can effectively move! This is also seen in the way that we look to build houses and showers without steps as we get older to help us compensate for our inabilities, rather than determining if those inabilities can be improved to allow us to continue to climb and walk effectively reducing our risk to pain and injury while continuing to be able to move.
Experiencing Knee Pain?
If you are experiencing knee pain and want to know if there are other options besides pain management (anti-inflammatory medications, cortisone injections) that may be able to help you and restore your ability to move and live a more active life, please consider scheduling an appointment with our office. Let us help you get back to the life that you deserve! In the meantime, check out the following posts to get a jump start on some exercises that can be very beneficial to your knees!
…Till Next Time!
