What is patellofemoral pain syndrome?
Patellofemoral pain syndrome (PFPS), or better known as runners knee, is a general diagnosis to describe pain that is located at the patella-femoral joint. In other words, PFPS is pain at the front of the knee that stems from the articulation between the knee cap and femur. Pain is typically worse with running, squatting, sitting for long periods of time, and walking up/down stairs. Other causes of knee pain located at the front of the knee include chondromalacia patella, patellar tendonitis, and osteoarthritis of the knee. It is in your best interest to have a professional, such as chiropractor or physiotherapist, correctly diagnose your knee pain to ensure that your rehabilitation efforts are effective because the treatment strategy changes for each condition.
Understanding patella biomechanics and the compressive forces with knee flexion.
At full knee extension there is minimal to no contact of the patellar and the trochlear groove of the femur. In other words, when the knee is straight there is minimal contact and, thus, minimal compressive forces between the patella and the trochlear groove. The trochlear groove is essentially a depression in the femur to guide the patella downwards during knee flexion (heel to butt).
At the start of knee flexion, the patella glides downwards and begins to make contact with the trochlear groove of the femur. This contact is when the compressive forces initiate at the patellofemoral joint.
The compressive forces peak rapidly between 30 to 60 degrees of knee flexion.1 For this reason, it is logical why PFPS pain is typically worse with prolonged sitting and weight bearing movements such as squatting or walking up or down stairs.
To be clear, in a healthy knee, these compressive forces are normal and the patellofemoral joint is built to handle this stress. However, if there is damage to the articulating surfaces of the patella or femur, it may exacerbate the pain.
Poor Patellar Tracking
The soft tissues surrounding the patella can prevent the patella from tracking down the trochlear groove optimally and can lead to wear and tear of the articular cartilage. Most cases of dysfunctional patellar tracking are due to a tight IT band and tight lateral reticulum with vastus medialis weakness. This combination deviates the patella laterally and the individual and is bearing more force on one side of the patella. Therefore when participating in activity which requires knee flexion, one side of the patella is working over time and the other side of the patella is taking a vacation. This unequal workload is what leads to inflammation and, ultimately, pain at the front of the knee.
Essentially, the overall goal is to:
- minimize patella and femoral compressive force while restoring proper knee biomechanics
- maintain strength of the hips while rehabilitating the knee
The Romanian deadlift will maintain the strength of the core, glutes and hamstrings while allowing the knee to heal. The Romanian deadlift is a deadlift variation where you start from the top portion of the dead lift and lower the weight using the hips with minimal knee flexion and then return to neutral. The compression forces of the patella-femoral joint are very small due to the lack of knee flexion associated with the movement.
To restore proper alignment of the patella without stressing the patellofemoral joint during acute symptoms, terminal knee extension is a good place to start. Terminal knee extension strengthens the vastus medialis and offsets the pull of the IT band and lateral retinaculum on the patella. To add to the therapeutic effect of terminal knee extension, the patella has minimal contact with the trochlear groove during the exercise and, thus, mitigates the compression forces between the structures. Below is a video describing how to perform terminal knee extension.
In addition to strengthening the vastus medialis, I recommend also decreasing the tension of the IT band which pulls patella laterally. In my previous blog, I mentioned that the tensor fascia lata (TFL) and 1/3 of the gluteus maximus both attach to the IT Band. When these muscles become tight or restricted, there is an increase in amount of tension/tightness of the IT band due to their common insertion.2 Therefore your strategy should include lengthening these structures to regain neutral patellar alignment. I included videos below on how to do so.
By no mean is this a complete rehabilitation program for runner’s knee. This is just a starting point to understand the mechanism of the injury and how to begin the rehabilitation process. I suggest you book an appointment with a professional, such as chiropractor or physiotherapist, to aid you in your journal of back to optimal function.
- Kisner, C., & Colby, L. A., 2012. Therapeutic exercise: Foundations and techniques (7th ed.). F.A. Davis., pp. 773
- Kisner, C., & Colby, L. A., 2012. Therapeutic exercise: Foundations and techniques (7th ed.). F.A. Davis., pp. 720