Preventing Anterior Knee Pain and Yoga

Patellofemoral pain syndrome (PFPS) is the most common overuse injury of the lower extremity 1, 2. PFPS is a condition characterized by pain surrounding the kneecap associated with activities involving lower limb loading (eg, walking, running, jumping, stair climbing, and prolonged sitting and kneeling (yoga!)). There are many factors that can lead to PFPS3. These include:

1. ) Alignment: the angle your thigh bone (femur) connects to the shin bone (tibia), the way the knee cap (patella) fits onto your femur, and the way your ankle and foot line up with the shin bone.

2.) Muscle strength: the muscles that influence the hips, knees and ankle all influence your alignment and knee function.

3.) Muscle tightness: if the muscles that cross the knee and attach to the patella are tight, it will cause increased compressive forces and may also influence how the patella moves.

There is not always an obvious reason why someone has anterior knee pain. PFPS is often associated with higher impact activities, but may occur in yoga. Regardless of whether practicing yoga aggravates your knees, learning more about the patellofemoral joint may help you improve your alignment and avoid unnecessary strain and pain.

The knee bone’s connected to…

The knee is made up of three bones: the thighbone (femur), the shinbone (tibia), and the kneecap (patella). The patella is a large sesamoid bone (a bone embedded within a tendon) and protects the knee from direct trauma. It also acts as a fulcrum for extension of the quadriceps so we can effectively straighten and bend our knee. The patella sits in the trochlear groove or fossa at the distal thigh and becomes more congruent with the femur as the knee bends into flexion. It may help to imagine a train on a track. The patella represents the train and the trochlear groove representing the track. Where the patella sits on the knee is called the patellofemoral joint (train on the track) – one of the most complex joints in the body.

The knee has 16 muscles that influence its mechanics and function. Some of the muscles that cross the knee also influence the hip, and others influence the ankle. It’s important to consider both your hip and your ankle alignment during yoga because of the direct relationship both have on proper knee function. The most relevant muscles to consider for knee stability are those that cross the knee: the quadricep group and the hamstrings. The gluteals (buttocks) and the peroneal muscles (ankle evertors) are also relevant due to the effect they have on hip and ankle alignment.

When you perform standing poses such as Warrior II or crescent pose (a lunge type position), it may help to lessen the bend so the knee is behind rather than beyond the ankle to prevent excessive strain to the patellofemoral (PF) joint. The amount of force placed on the PF joint increases with increasing knee flexion. The more we bend, the more compressive force we place on and behind the patella. This is not a problem in a healthy knee because the congruency of the back of the patella to the distal part of the thigh bone is normally snug, dispersing the forces through a larger surface area. However, if our thigh bone rolls in, or our shin bone rolls in or out, congruency can be affected as the patella moves up, tilts, or shifts to the outside (the train begins to tilt on the track or the track tilts away from the train). Poor “patellar tracking” increases the forces through the PF joint, the PF tendon and the connective tissue surrounding this bone.  It can lead to degeneration of cartilage and irritation of soft tissue.  Ultimately both the ‘train’ and the ‘track’ become damaged.

Tips for a comfortable knee in yoga

If you struggle with keeping the knee (patella) pointing directly forward during lunge type poses, try these tips:

1) Angle the front foot in slightly before stepping back (big toe in very slightly and heel out).  Turning the foot in slightly will help to align the outside part of your foot with the long end of your mat. In this alignment, you can better engage your outside hip muscles by attempting to push your heel bone inwards and foot outwards (abduction).

2) Lengthen the lunge. Stepping back further in a lunge position (if hip flexibility allows) has been shown to lessen the force through the PF joint4.

3) Lean the body slightly forward from the hips. With the shoulders slightly in front of the hips, forces are transferred towards the hip rather than your quadriceps and knee.

If you feel like your knee is aligned properly, you’ve tried these tips and continue to feel pain, it may be due to muscle or connective tissue tightness. If the patella (train) doesn’t move well and is pressed tightly against your bones (track), it will irritate the prepatellar bursa (fluid sac that protects tendons from rubbing against bones), retinaculum surrounding the patella, and the cartilage under the patella. None of these forces is good.  In this case, working on flexibility and mobility of the muscles that cross the knee and the knee cap itself are often helpful. Poses that stretch the outside portion of the hips (the iliotibial band) like reclined spinal twist are often beneficial.

In poses such as triangle, where the leg is straight, micro bend the knee and press through the ball of the front foot to activate the gastroc muscle group in your calf. This action will assist in stabilizing the knee and take pressure off the patellar tendon. Also gently pressing the heel of the front foot inward to activate the hip external rotators helps to line up hip, knee, ankle and limit hip internal rotation.

Patellar tracking problems can be problematic in not only triangle or lunge poses, but also yoga poses such as bow. When performing Bow Pose (on belly, backbending and grabbing both ankles with hands), Dancer Pose or any variation of these poses where you grab your feet or foot, it helps to activate your thigh muscles (quadriceps) by gently pushing the feet into the hands to activate a reflex called the myotactic stretch reflex. This reflex results in the muscle relaxing as it is being stretched so it can lengthen rather than resist being lengthened. If we simply grab our feet, it can squash our back, but also it makes the effort more passive, and our muscles may respond by actually tightening when we are trying to stretch them. If you feel a worsening of symptoms with increased knee flexion, poses such as hero (sitting on shins with knees fully bent) are not advised. Increased pressure can result in further irritation to the joint and surrounding structures. Modifying these poses with props such as sitting on a block, or avoiding these poses all together is a good idea. Yoga should never hurt.

Putting it all together

In summary, if you have anterior knee pain, make sure you consider where your patella is facing in your poses. It should always be in line with your hips and your ankles. Modify poses and use props if necessary to lessen the bend in the knee or to compensate for muscle weakness. If you struggle with your knee rolling in standing poses, work on building up your gluteal strength. Bridge Pose and Bird Dog have been proven to be superior in isolating gluteal muscles. Performing balance poses can be an effective way to strengthen the leg and ankle. When standing on one leg, try to grip with your toes slightly to strengthen the arch of the foot. You may need to hold onto something or place the toes of the elevated leg down until you can maintain your balance with good form.  If you still have pain despite these fixes, you may benefit from seeing a specialist.

Practicing SMART SAFE yoga means protecting your precious knees by keeping the train running smoothly on the track!
 

Reprinted with permission of Dr. Matthew Taylor and smartsafeyoga.com.

Christine Carr is the owner of Synergy Physical Therapy and Yoga, Inc. in Evergreen, Colorado. She incorporates both physical therapy and yoga in her work helping clients (synergyptyoga.com). She has been a physical therapist for 18 years and a yoga therapist for 11 years. Christine has studied with various yoga teachers and styles being drawn most to the Iyengar lineage and therapeutics in general. She now assists workshops in therapeutics for both the Professional Yoga Therapy Studies and Rachel Krentzman’s Yoga for a Happy Back Program. Her passion for learning and contributing to her field led her to Dr. Matthew Taylor, PT, PhD, E-RYT 500 for whom she is now contributing articles for his SmartSafeYoga blog.

References

1. http://www.jospt.org/doi/pdf/10.2519/jospt.2010.0302

2.Journal of Orthopaedic Sports Physical Therapy, 2012, Volume: 42 Issue: 2 Pages: 81-A12 doi:10.2519/jospt.2012.3803

3.http://www.ncbi.nlm.nih.gov/pubmed/14669964

4.http://www.ncbi.nlm.nih.gov/pubmed/18978453

5.http://www.jospt.org/doi/full/10.2519/jospt.2013.4116#.VY3dnGA-BQN