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Patellofemoral pain syndrome

Patellofemoral pain syndrome can be defined as retropatellar or peripatellar pain resulting from physical and biochemical changes in the patellofemoral joint. It should be distinguished from chondromalacia, which is actual fraying and damage to the underlying patellar cartilage. Patients with patellofemoral pain syndrome have anterior knee pain that typically occurs with activity and often worsens when they are descending steps or hills.

It can also be triggered by prolonged sitting. One or both knees can be affected. Consensus is lacking regarding the cause and treatment of the syndrome. The patella articulates with the patellofemoral groove in the femur. Several forces act on the patella to provide stability and keep it tracking properly (Figure 1).

A common misconception is that the patella only moves in an up-and-down direction. In fact, it also tilts and rotates, so there are various points of contact between the undersurface of the patella and the femur. Repetitive contact at any of these areas, sometimes combined with maltracking of the patella that is often not detectable by the naked eye, is the likely mechanism of patellofemoral pain syndrome. The result is the classic presentation of retropatellar and peripatellar pain.

This pain should not be confused with pain that occurs directly on the patellar tendon (patellar tendonitis). Many theories have been proposed to explain the etiology of patellofemoral pain. These include biomechanical, muscular and overuse theories. In general, the literature and clinical experience suggest that the etiology of patellofemoral pain syndrome is multifactorial.

CAUSES
FIGURE 2. Pes planus, or flat foot (left), in a non­weight-bearing state. Loss of the medial arch with weight-bearing (right) causes the ankle to "roll" medially. To compensate, the femur or tibia rotates internally, increasing valgus and stressing the patellofemoral mechanism. Arch supports can help with this problem.

Biomechanical Problems and Muscular Dysfunction
No single biomechanical factor has been identified as a primary cause of patellofemoral pain although many have been hypothesized. Some of the more popular theories are discussed in the following sections.

Pes Planus (Pronation)
The terms "flat feet" and "foot pronation" are often used interchangeably. Technically speaking, foot pronation is a combination of eversion, dorsiflexion and abduction of the foot. This condition often occurs in patients who lack a supportive medial arch (Figure 2). Foot pronation causes a compensatory internal rotation of the tibia or femur (femoral anteversion)¹¹ that upsets the patellofemoral mechanism. This is the premise behind using arch supports or Prescription Orthotics in patients with patellofemoral pain.

Pes Cavus (High-Arched Foot, Supination).
Compared with a normal foot, a high-arched foot provides less cushioning for the leg when it strikes the ground. This places more stress on the patellofemoral mechanism, particularly when a person is running. Proper footwear, such as running shoes with extra cushioning and an arch support, can be helpful. (It is preferable to purchase such footwear from a reputable athletic shoe store with knowledgeable staff.)

Muscular Causes
The potential muscular causes of patellofemoral pain can be divided into "weakness" and "inflexibility" categories Weakness of the quadriceps muscles is the most common factor with tightness in the hamstrings also being involved.

Symptoms
Cinema sign (pain in the knee when sitting for long periods of time)
The other symptom frequently reported is pain ascending or descending stairs and hills

What can you do
Exercises for patellofemoral pain are based on the muscular causes.Quadriceps strengthening is most commonly recommended because the quadricep muscles play a significant role in patellar movement. Hip, hamstring, calf and iliotibial band stretching may also be important. The decision to incorporate these additional exercises depends on an accurate physical examination.

Guidance from a physical therapist can be helpful, but patients need to adhere to the therapist's recommended home program and should not expect overnight success. Patients may not experience improvement of symptoms for six weeks or much longer, and the syndrome may recur.

What the Physical Therapist may do
Following a full functional assessment the problematic musculoskeletal structures will be addressed
An exercise programme will be prescribed to strengthen and lengthen the relevant areas affected
Taping of the knee cap (patella) in some cases may help
If a dysfunctional gait / foot is found as in the case of Pes Cavus / Planus to be the causative factor Prescription Orthotics will be prescribed in order to correct the dysfunction and improve gait