Knee Pain - Patellofemoral Pain Syndrome

There are various types of knee conditions / pain. However, for the sake of length (of which this article will be long enough) and that of testing the reading endurance of you (the reader), I will mainly focus on the most common knee condition (whilst providing links to others). The knee condition I feel worth addressing in detail (because I see it to be most common) is a condition known as Patellofemoral Pain Syndrome (PFPS); also been phrased as either Patellofemoral Joint Syndrome, Anterior Knee Pain, Maltracking Patellae, Patella Pain Syndrome, Runner's Knee or Chondromalacia Patellae (thinning and softening of the articular cartilage under the patella and/or lateral or medial femoral condyles). 

Patellofemoral pain syndrome can be defined as a Retro-patellar (behind the knee cap) or Peripatellar (around the knee cap) pain, resulting from physical and biomechanical changes on the Patellofemoral joint. The condition is usually the result of the kneecap (patella) not tracking / gliding smoothly through the femoral groove when the leg is bent and straightened (see Fig. 1 below).

 

 

 Fig. 1:

People that have PFPS have anterior (front) knee pain that typically occurs with activity and often worsens when going up/down steps or hills, squatting, kneeling, running or other jarring activities that involve knee bending. The pain can occur with sitting for prolonged periods of time and affect one or both knees at the same time (however, usually one).

Patellofemoral pain syndrome can also be more common during adolescence, due to the long bones growing faster than the muscles, tendons and ligaments... thereby putting excess stresses on joints. Active children who do not stretch the appropriate muscles are predisposed to patella malalignment / irritation.

 

This condition could potentially be multifactorial (have many causes)... meaning it could be muscle related (i.e. imbalance/weakness/flexibility), structural related (bone/joint issues) with associated biomechanical factors (i.e. adverse joint angles, movement and subsequent forces directing excess stress to soft tissues and joints)... but possibly related to one prime cause i.e. lower limb function (i.e. foot function) or hip function (i.e. weak hip muscles) [or possibly an element of both]... which is good, as if you address the primary cause the other issues will gradually resolve.

The potential muscular cause of Patellofemoral pain can be divided into "weakness" and "inflexibility". Weakness of the quadriceps muscles is the most often area of concern... with the Vastus Medialis / Vastus Medialis Oblique (VMO) being the usual culprit. Weakness of the VMO (Vastus Medialis Oblique) allows the patella to track too far laterally... thus trauma on the underneath surface (see Fig. 1 above). The VMO is difficult to isolate, and may need specific strengthening exercises to strengthen the muscle. Also, there may be tightness associated with the lateral part of the quadriceps muscle i.e. the larger and stronger Vastus Lateralis muscle... which could potentially pull the knee cap (patella) sideways laterally... thus both of which contributing to the lateral maltracking over the femoral groove (see Fig. 2 below). Hence a combination of strengthening the medial side of the quadricep (Vastus Medialis - VMO) along with stretching / massaging the lateral side of the quadricep (Vastus Lateralis) will help resolve the muscle related component of this injury (see exercise video below). 

Adductor muscles of the hip play a role in the stability of the pelvis, which can cause an external rotation which may result in compensatory foot pronation (see Fig. 2 below). A simple stretch can improve muscular efficiency as well as developing strength in the Glutes (buttock muscle region) to help stabilise hip whilst running can be very effective. Improvements in hip flexion strength combined with increased Iliotibial Band and Iliopsoas flexibility are associated with excellent results in patients with Patellofemoral pain syndrome.

Tight Calf muscles can also lead to compensatory foot pronation... and like the hamstrings they can increase the posterior force on the knee.

 

♦♦♦ Therefore, with the above possible factors involved, it is important to be adequately assessed (i.e. via a Biomechanical Assessment) to make sure the pain is properly diagnosed and the causes are found and addressed... for effective treatment. 

Fig. 2:

 ♦ Symptoms:

- Knee pain is usually felt under and/or around knee cap.

- Pain is felt after sitting with knee bent.

- Pain may be felt after running down hill or walking down steps.

- Pain may be felt on squatting and kneeling.

 

 ♦ Causes:

The patella (kneecap) rests in the femoral groove of the thighbone (femur). Maltracking of the patella irritates the femoral groove (as well as underside of patella) and then pain is felt. This maltracking can be caused by the following:

- The patella sitting too high in the femoral groove which may be due to tight quadriceps muscles.

- Growth spurts (in adolescence) due to the long bones (i.e. Femur) growing faster than the muscles, tendons and ligaments... thereby potentially putting excess stresses on joints. 

- High arch feet which provide not enough shock absorption.

- Functionally or structurally 'flat feet' can affect the tracking of the patella over the femoral groove due to the act of excess pronation (therefore excess medial rotation of lower limb).

- Worn cartilage in the knee joint reduces shock absorption.

- Knock knees (Genu Valgum) can also affect the tracking of the patella over the femoral groove.

- Tight muscles, e.g. hip adductors, quadriceps (in particular Vastus Lateralis), hamstrings and calf muscles can affect the tracking of the patella.

- Weak muscles, e.g. quadriceps - in particular the Vastus Medialis (VMO) branch of the quad. muscle can cause the patella to track out of alignment.

- Running too much on a cambered surface also affects the tracking of the knee joint as well as old, worn out running shoes (poor wear pattern).

- Inappropriate running shoes for that particular sportsperson / athlete.

- Women can be predisposed to this injury due to their wider pelvic girth (i.e. higher Q angle).

- Sudden increase in running mileage and / or hill training.

 

It can sometimes be vague as to which is the root/primary cause... a bit like the chicken/egg scenario if you like (what contributed to what first), but if you do not control a present potential pathologic foot function (providing one exists), the outcomes will rarely hold just by focusing on the hip (i.e. Glutes) and Quad (i.e. Vastus Medialis) musculature alone (thus symptoms may return).


♦ Treatment:

- When symptoms first develop, it may be of help to ice the area for 15 - 20 min. after the activity.

- Running should be decreased to reduce stress and encourage healing.

- Avoid downhill running.

- Avoid exercises where the knee is bent too often under strain / load (i.e. step / stair climbing).

Quadricep exercises - Strengthening and Stretching i.e. straight leg lefts, knee extension exercises etc... (particularly strengthen the medial quad. muscle - VMO). There are many various ways to stretch and strengthen the Quad. muscle group... the following is the best video I could find to demonstrate some of these...

 

Massage (and stretch) possible tight lateral Quad. / thigh region (i.e. Vastus Lateralis, Iliotibial Band), as well as posterior muscles (i.e. calf muscles and hamstrings). Massaging via a Foam Roller (see Fig. 3 and 4 below) is very beneficial when intending to massage areas such as the Vastus Lateralis and Iliotibial Band...

                       Fig. 3:                                                        Fig. 4:

 

  

- Do not wear old, worn-out shoes with poor wear (sole) pattern... this will contribute to faulty lower limb (foot) mechanics / movement.

- Orthotics may be required if there is a biomechanical condition, e.g. excess pronation (i.e. excess medial rotation of lower limb). Research has indicated that providing a more conducive lower limb function via aiding more conducive foot mechanics will help the muscles (i.e. Vastus Medialis) activate more efficiently to help optimally control knee function thus reducing the risk of Patellofemoral related pain arising.     

- Strapping: to help keep the Patella in a better position... as well as help increase Vastus Medialis (VMO) activation. The following instructions is of one technique which can be an effective way to do this - Patella Strap (link). However, the following video demonstration is likely more effective for specific Patellofemoral Pain Syndrome...

 

 

- If symptoms persist, the Podiatrist may order diagnostic imaging studies, such as X-rays, Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans for deeper investigation to assess any damage to the structure of the knee and the tissues that connect to it... which may be indicative of other knee related pathologies, such as...

- Osgood-Schlatter Disease.

- Patellar Tendinitis.

- Prepatellar Bursitis.

- Plica Syndrome.