What is Patellofemoral Osteoarthritis?

The patellofemoral joint (PFJ) is one of the two joints which make up the knee complex. The patella (kneecap bone) is located at the front of the knee and is responsible for increasing the strength and power of the quadriceps.

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The patellofemoral joint (PFJ) is one of the two joints which make up the knee complex. The patella (kneecap bone) is located at the front of the knee and is responsible for increasing the strength and power of the quadriceps (the large muscle group at the front of the thigh).

The patellofemoral joint is created by the patella (kneecap bone) and the femoral condyles of the femur (two large bony prominences located at the end of the long bone of the upper thigh). These two bony prominences create a central concave ‘V’ shaped groove (known as the trochlea) which perfectly fits the back of the patella, which has a reciprocally convex shape.

Risk factors associated with patellofemoral osteoarthritis include:

• Sex – recent studies have shown a slightly increased rate of patellofemoral osteoarthritis in women (13.6 to 24%) compared with men (11 to 15.4%) (Kanazawa et al., 2017)
• Age – patellofemoral osteoarthritis is most commonly observed from the fifth decade onwards (Kanazawa et al., 2017)
• Hip muscle weakness – strength deficits in the hip can adversely affect lower limb alignment and have been shown to significantly increase the risk of patellofemoral osteoarthritis (Souza et al., 2009)
• Femoral structure – the upper end of the femur (the long bone of the thigh) forms the ball of the hip joint. In some people the angle of this ball-shaped end of the femur is altered. This is called femoral anteversion and has been linked with increased risk of patellofemoral osteoarthritis (Souza et al., 2009)
• Patella position and structure – if the back of the patella does not align within the trochlea of the femoral condyles precisely, adverse pressure is piled on the articular cartilage resulting in osteoarthritic change
• Weight – high body mass index (BMI) has been linked to the onset of osteoarthritis
• Repetitive overloading of the patellofemoral during certain types of activity such as running, jumping and hopping
• Poor foot biomechanics – excessive pronation (flat foot) can result in increased pressure through the PFJ