Patellofemoral Joint (PFJ) pain is the most common knee problem and accounts for 25% of all knee injuries and is more common in females than males.(1)  Conservative treatments may consist of stretching, strengthening, balance exercises, and working on biomechanics.  But the individual dealing with the injury or the person treating that individual should consider appropriate interventions while avoiding exacerbation of symptoms and injury.

In this article, I will focus on quadriceps muscle strengthening as one aspect of conservative treatment.  Usually during a pain flareup an individual will more likely avoid certain positions leading to weakness of the leg muscles and eventually poor mechanics.  To avoid the progressive weakening of the quadriceps muscles it is important to complete exercises.  What exercises would be okay to complete without overly stressing the patellofemoral joint?

An article I just reviewed assessed the force of the patella on the femur during common rehabilitation exercises for the knee; the squat and seated knee extension.  The study showed that completing a squat from 0-45 degrees of knee flexion and seated knee extension from 90-45 degrees of knee flexion would be optimal to avoid overly stressing the PFJ.  Complete 10 repetitions 2-3 times a day and increase 5 repetitions every two weeks until you are able to complete 25 repetitions of each exercise without pain.  These exercises should be incorporated into the initial stages of PFJ rehabilitation until an individual is able to go up and down stairs or transitioning from sitting to standing from a chair without pain.  Then these exercises may be progressed to the full ranges.

Squats from 0-45 Degrees of Knee Flexion

Seated Knee Extension from 90-45 Degrees of Knee Flexion


1. Sueki D, Brechter J. Orthopedic Rehabilitation Clinical Advisor. Maryland Heights, MO: Mosby, Inc.; 2010.

(Click the link below for access to the article)

Patellofemoral Joint Stress During Weight-Bearing and Non-Weight-Bearing Quadriceps Exercises

Purpose: To compare patellofemoral joint stress among weight bearing and nonweight bearing quadriceps exercises.

Methods: They assessed the knee musculature of squatting exercise (weight bearing) and two nonweight bearing knee extension exercises (seated knee extensions with variable resistance and seated knee extensions with constant resistance).  They used 10 subjects (5 male and 5 female) who did not have knee pain.

Results: They found that the squat produced significantly higher PFJ stress from 90-60 degrees knee flexion.  They reported that the two nonweight bearing exercises had significantly higher stresses from 30-0 degrees knee flexion.  And more specifically that the variable resistance produced significantly less stress than the constant resistance.

Limitations: There were 5 limitations with this study.  First, they only studied healthy individuals so the results should not be generalized to other populations.  They did not compare the exercises to a gold standard.  The researchers did not control the trunk position during the squat exercise which could change the muscle activity of the quadriceps.  They considered the segmental accelerations during the nonweight bearing exercises negligible and were not factored into the calculations.  Finally, they only studied concentric muscle activation and recommended that future studies assess eccentric muscle contractions.