Physical Therapy Series: Knee Pain
25% of adults have knee pain and its prevalence has increased over 65% in the last 20 years. 15% of adults over 60 years old have symptomatic arthritis which results in 10-15 million doctors visits annually. In my practice, the most common reason for visits in older patients is arthritis and degenerative meniscal tears. In younger patients, the most common reason visits involving knee pain is sport or work injuries. In either case, almost all knee ailments will benefit from physical therapy. Even the worst injuries that require surgery to repair ligaments or tendons, or arthritis that may need a knee replacement will require physical therapy to have a good result. Minor injuries will often require therapy to fully recover or to prevent the injury from recurring. In middle aged and older patients we often see a wide range in pain and symptoms compared to the amount of arthritis or other findings on x-ray or MRI. Some patients with arthritis have severe pain and others are asymptomatic even though they have similar findings on radiological studies. I have frequently discussed that some patients have lower levels of chronic inflammation which allows them to tolerate joint damage. Another factor in how much knee pain one may experience is patients with strong and flexible knees tolerate more joint damage, have less symptoms, and recover from injury faster. You will often hear me say “there are people out there running marathons with knees that look like yours”. This is where physical therapy comes into play in the “preventive phase”, the “injured phase”, and the “recovered phase”. I discussed in the therapy blogs on back pain and shoulder pain that I wish everyone took a few minutes each week to do shoulder and back exercises to prevent injury. This is not always the case with knees. If you have ever done therapy for your knees, or you watch the videos in this blog you may see that many of the exercises are already in your daily routine if you are active. Most functional strength classes will strengthen your legs and maintain mobility similar to therapy exercises. Many manual labor jobs will incorporate these same motions. However, if you are not active you should consider some of these programs to prevent future knee problems. If you have ever had a knee injury, you should consider a functional strength program or a home therapy program to prevent future problems.
Many knee issues are successfully treated with surgery. ACL tears requiring reconstruction or meniscus tears requiring repair or removal are the most common surgeries in young and middle aged patients. Many of these patients make a full recovery, but should be aware they are not completely out of the woods because most meniscus, tendon, and ligament surgeries are associated with future arthritis. Now that’s not to say these surgeries cause arthritis. In fact, the arthritis would be much worse if you did not have surgery, but even the best surgery does not result in the perfect anatomy with which you were born. Therefore even if you are fully recovered you should make every effort to maintain your strength and mobility after any surgery - this is where PT comes into play. You should also maintain your ideal weight as extra weight will wear down your knee more quickly and make the damage less tolerable.
A common misconception is that running is bad for your knees. Research shows that this is not the case and that running will actually strengthen normal, healthy knees. On the other hand, and I believe this may be where the misconception comes from, running could accelerate arthritis in previously injured knees. This does not mean that someone who has had an arthroscopic meniscectomy, ACL reconstruction, or has early arthritis should not run, but they should consider cross training instead of just long distance running in an effort to limit damage to their knees as they age. For some ideas on how to be a runner without running long distances repetitively read my blog “I Ran Today”.
Causes of Knee Pain
Why do so many people have knee problems? This video discusses this question from an evolutionary biology standpoint, but the video is somewhat mistitled. The knee is actually an amazing design, but we may be asking too much of it. Our knees are similar to other primates but we put more force on our knees as we have evolved to walk upright. The force which was once on four joints is now carried by two. A striding gait is more efficient for upright walking but requires a narrow pelvis. However, our pelvis needs to be big enough to deliver our big brained babies. This conflict results in human child birth being far more dangerous than other primates. This is the reason for C-sections. The argument can be made that the greatest medical contribution to humanity has been OB/GYNs making birth far safer in modern times. The balance between a wide pelvis for birth and a narrow pelvis for walking results in knee alignment that can be prone to injury.
A major reason for knee issues is our increasing life span. As a species, a human's goal is to have as many healthy children and grandchildren as possible to pass on our genes. However, we are now living much longer than our biological function requires so we are outliving our knees. Our big brains have developed a world where food scarcity is rare which is a great accomplishment in certain aspects but results in our increasing weight which puts further force on the knees. Finally, our work and athletic activities result in further knee trauma. Ligament and cartilage injuries like ACL tears can occur from forceful contacts that are more common in modern sports. Many injuries however, are non-contact injuries which can occur from quick changes of direction, sudden deceleration, or jumping. These movements are common in modern sports, but are also a part of many activities in life. Knee injuries are more likely if there is any muscle imbalance in the core or hips, or when these muscles are fatigued. These are issues that can be improved with a proper injury prevention program.
ACL Injuries
While an ACL injury can occur in anyone, female athletes are 8 times more likely than men to have ACL tears. The following video gives several theories why this is but no research has made a definitive conclusion. Some theories are related to anatomical differences with women having wider pelvises, thinner ACLs, and smaller ACL notch (the notch in the femur where the ACL attaches). Other theories relate ACL injuries to women having more flexible joints and to changes in laxity related to hormone fluctuation at different times during the menstrual cycle. There is also some evidence women have weaker quadricep muscles compared to their hamstrings whereas men are more balanced. What has been proven is women can train to decrease the incidence of ACL tears. The following video explains these theories.
The following is an ACL tear prevention program. This can be a part of practice or workouts. It would be beneficial to men and women.
The 7 Exercises for ACL Strengthing:
Squat
Jump Squat
Lateral bound
Step Up
Hamstring curl
Ball walkout
Deadlift/ Romanian Deadlift
Patella Pain
Another common problem in knees is patellar (kneecap) maltracking. In younger patients, this issue results in patellar chondromalacia (inflamed patellar cartilage) ,and in older patients this results in patellofemoral arthritis. The patella is supposed to track centrally in the femoral groove. Weak or imbalanced quadricep muscles or weak hip muscles can cause the patella to track slightly to the outside. This maltracking results in pain and ultimately arthritis of the kneecap as the years add up. We often see this as young as preteens due to lack of quadricep development. Patients complain of pain going up or down steps and kneeling. The main treatment is always physical therapy.
Exercises for Patella Pain:
Patellar mobilization
Leg Lift and leg Lift with foot externally rotated
Hip Abduction
Hip Hike- Hip Abduction
Stair Step
Reverse Lunge
Band Walk and Lateral Band Walk- you can do this without a band
Meniscal Tears
Meniscal tears are a common reason for knee pain. In younger patients, the injury is usually a forceful trauma and the treatment is usually surgery. Older patients often have degenerative tears of the meniscus. Any injury to the knee could cause a meniscal tear or aggravate a previously asymptomatic tear. An MRI will confirm the tear but it will not always determine the stability of the tear. If the tear is unstable it will flip in and out of the joint often causing locking. Locking is when the joint gets stuck as opposed to just stiff. Therapy can help degenerative meniscal tears recover nonoperatively and in the postoperative period if patients require surgery. Research is showing that degenerative tears that do not cause locking do not benefit from arthroscopic surgery which is another reason it is important to commit to therapy.
Exercises for Meniscus Tears:
Heel Slide
Quad set- Isometric quad strengthening exercise
Straight leg raise
This is a simple and effective program for meniscus tears as well as recovery for knee arthroscopy and partial meniscectomy.
Knee Arthritis
Ultimately the knee develops arthritis as many of us age. Basically the cartilage thins, cracks, and flakes off. When you hear someone say the surgeon scraped out the arthritis they mean the surgeon shaved down the flaking cartilage. This means they have less cartilage moving forward. Cartilage can only be replaced when the cartilage loss is in a small area of the knee. As I stated before, a strong and flexible knee is tolerant of a far greater degree of arthritis. Therapy will often help a patient with more severe arthritis avoid or at least delay surgery. If someone ultimately needs knee replacement surgery the therapy was not a waste of time. These patients who are strong and flexible will have a much quicker and better recovery.
Mobility Exercises for Knee Arthritis:
Heel slides flexion/extension
Strengthening Exercises for Knee Arthritis:
Band quad exercise- you can do these without a band
Seated knee knee extension
Wall squat- adjust to the level of your strength
Lateral step down- this requires some balance so use a chair or a wall if needed
Functional Exercises for Knee Arthritis:
Walking or biking
Squat
Calf raises- strengthening your lower leg will help your gait tolerate some knee arthritis
Side plank- strengthening your core will help you tolerate some degree of knee arthritis
Strengthening Exercises for Knee Arthritis:
Knee extension exercises
Knee flexion exercises-Child's pose
Knee pain can often make patients inactive as they age. Think of the knees as the tires on the car. A car needs to be driven even if the tread on the tire is wearing down or the engine will rust. The human body needs to be active even if the knees are wearing down or the body will develop far greater issues like heart and lung diseases. Maintaining a healthy weight and working to keep your knees strong and flexible will go a long way toward aging gracefully.