Abstract
Patellofemoral syndrome (PFS) is one of the most common conditions in sports medicine and is the most common diagnosis of anterior knee pain. PFS is a clinical diagnosis with an absence of other pathologies. Mainstay of treatment is a comprehensive conservative approach as outlined in this chapter. Rarely is surgical intervention required.
Keywords
anterior knee pain syndrome, chondromalacia patellae, knee joint, patellofemoral pain syndrome, patellofemoral syndrome
| Synonyms | |
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| ICD-10 Codes | |
| M17.9 | Osteoarthritis of knee, unspecified |
| M13.861 | Other specified arthritis, right knee |
| M13.862 | Other specified arthritis, left knee |
| M13.869 | Other specified arthritis, unspecified knee |
| M23.50 | Chronic instability of knee, unspecified knee |
| M23.51 | Chronic instability of knee, right knee |
| M23.52 | Chronic instability of knee, left knee |
| M25.561 | Pain in right knee |
| M25.562 | Pain in left knee |
| M25.569 | Pain in unspecified knee |
| M22.2X1 | Patellofemoral disorders, right knee |
| M22.2X2 | Patellofemoral disorders, left knee |
| M22.2X9 | Patellofemoral disorders, unspecified knee |
| M22.3X1 | Other derangement of patella, right knee |
| M22.3X2 | Other derangement of patella, left knee |
| M22.3X9 | Other derangement of patella, unspecified knee |
| M22.40 | Chondromalacia patellae, unspecified knee |
| M22.41 | Chondromalacia patellae, right knee |
| M22.42 | Chondromalacia patellae, left knee |
Definition
Patellofemoral syndrome (PFS) is the most common ailment involving the knee in both the athletic and the nonathletic population. In sports medicine clinics, 25% of patients complaining of knee pain are diagnosed with this syndrome, and it affects women twice as often as men. Yet despite the common occurrence of this disorder, there is no clear consensus on the definition, etiology, and pathophysiology. The most common theory is that the syndrome is an overuse injury from repetitive overload at the patellofemoral joint. This increased stress results in physical and biomechanical changes of the patellofemoral joint. The literature has focused on identification of risk factors leading to altered biomechanics to produce poor patellar tracking in the femoral trochlear groove and thus stress at the patellofemoral joint. Possible pain generators include the subchondral bone, retinacula, capsule, and synovial membrane. Historically, the histologic diagnosis of chondromalacia, or deterioration of the cartilage, had been associated with PFS. However, chondromalacia is poorly associated with the incidence of PFS.
Symptoms
The patient with PFS will complain of diffuse, vague ache of insidious onset. The anterior knee is the most common location for pain, but some patients describe posterior knee discomfort in the popliteal fossa. The discomfort is aggravated by prolonged sitting with knees flexed (“theater” sign) as well as on ascending or descending of stairs and squatting because these positions place the greatest force on the patellofemoral joint. The patient may also experience pseudolocking when the knee momentarily locks in an extended position.
Physical Examination
The examination focuses on identification of risk factors that contribute to malalignment and rules out other pathologic processes associated with anterior knee pain. Tenderness to palpation at the medial and lateral borders of the patella may be appreciated. A minimal effusion may also be present. The results of manual testing for intra-articular disease, such as the Lachman (anterior cruciate ligament) and McMurray (meniscal) maneuvers, will be negative.
The presence of femoral anteversion, tibia internal rotation, excessive pronation at the foot, increased Q angle, and inflexibility of the hip flexors, quadriceps, iliotibial band, and gastrocnemius-soleus should be determined. The patella position (baja or alta, internal or external rotation) should also be assessed with the patient sitting and standing. Each of these factors has either a direct or an indirect influence on the tracking of the patella with the femur ( Fig. 74.1 ).
The Q angle is the intersection of a line from the anterior superior iliac spine to the patella with a line from the tibial tubercle to the patella ( Fig. 74.2 ). This angle is typically less than 15 degrees in men and less than 20 degrees in women. An increased angle is associated with increased femoral anteversion and thus patellofemoral joint torsion. However, a consensus on the importance of an increased Q angle is lacking. Tight hip flexors, quadriceps, hamstrings, and gastrocnemius-soleus will increase knee flexion and thus patellofemoral joint reaction force. A tight iliotibial band will increase the lateral pull of the patella through the lateral retinacular fibers. Isometric hip strength was not shown to be a predisposing component of PFS pain in women. It is imperative to assess each of these components in the lower extremity kinetic chain to prescribe a tailored physical therapy program for each individual ( Table 74.1 ).
