Patellofemoral pain syndrome (PFPS) is a medical diagnosis associated with pain at the anterior knee, including the patella and surrounding soft tissue structures. PFPS is seen across most sports. Common complaints include pain with prolonged knee flexion or with climbing or descending stairs. It is also commonly referred to as chondromalacia.1 Patients with patellofemoral pain may also complain of the knee giving way, which might be a result of quadriceps weakness or patellar instability.2
PFPS is one of the most prevalent diagnoses in the orthopedic setting; in fact, 2.5 million of the 20 million runners in the United States will be diagnosed with PFPS.3 As a result, gaining comprehension in a more efficacious manner is strongly suggested to be advantageous in treating these patients. Much of the literature on PFPS has focused on the diverse contributing factors; however, there are minimal rehabilitation protocols that integrate a multifactorial approach.
It is known to afflict female and youth athletes more than other subpopulations, and is one of the most prevalent diagnoses that require referral to physical therapy. Boling et al.4 studied 1525 participants from the United States Naval Academy and found the incidence rate for PFPS to be 22/1000 during a 2.5-year longitudinal study. Physicians and certified athletic trainers documented cases of PFPS based on diagnostic criteria. These criteria included pain with ascending/descending stairs, hopping/jogging, prolonged sitting, kneeling, and squatting. Furthermore, each patient had to be examined for pain with palpation of the patella or femoral condyles. The examination also served to rule out ligamentous or other soft tissue pathology. The study demonstrated a higher prevalence in females of 2.23:1, which echoes historical data.4
In 240 middle and high school female athletes the presence of PFPS occurred in 16.3 per 100 athletes, which supports the clinical data that young female athletes are the greatest at-risk population for developing patellofemoral pain.5
A 2006 examination of clinical and radiologic tests for patellofemoral pain by Haim et al.6 employed few sensitive tests, which could be validated for PFPS. Haim et al.6 evaluated the following tests: patellar tilt, active instability, patellar apprehension, and patella alta test. They found these four tests to have very low sensitivity (< 50%), but specificity ranges were moderate to high (72% to 100%). Physical examination findings that were deemed significant by the study included increased Q angle (Fig. 22.1), lateral and medial retinacular sensitivity, patellofemoral crepitation, squinting patella, and reduced mobility of the patella. From a radiologic perspective, only patellar subluxation was found to be a significant indicator for PFPS in the subject pool. These findings all highlight the need for a comprehensive examination in order to truly understand the etiology of PFPS with research-based support.
Gender differences in Q-angle. Women (right) exhibit a greater Q angle, increased external tibial torsion, and femoral anteversion. (Reproduced from Griffin LY. Rehabilitation of the Injured Knee. St. Louis, MO: Mosby-Year Book; 1995, with permission from Elsevier.).