PFPS is a term used to describe pain felt behind the knee cap where your thigh bone (femur) and knee cap (patella) articulate to form the patello-femoral joint. The patella lies within the femoral groove and normally glides up and down as your knee bends and straightens. When there is poor alignment of the patella (meaning it moves more to one side) it starts to rub against the surface of the femur. As this places the joint under excessive stress and irritation it results in pain and dysfunction during activities such as going up/down stairs, squats, hopping and even running. PFPS normally has a gradual onset rather than due to a traumatic event.
Mal-alignment of the patella can be due to a number of factors including muscle imbalance, poor biomechanics and sudden increases/changes in physical activity. The quadriceps (thigh) muscle is attached to the patella via the patella tendon. The vastus medialis oblique (VMO) muscle is responsible for pulling the patella inwards and the vastus lateralis (VL) muscle helps to pull the patella outwards. If there is an imbalance or delayed activation of the VMO then the patella will move laterally within the femoral groove. Weakness in your hip muscles can cause the knee to deviate inwards again resulting in the patella to move laterally.
Poor foot posture may also contribute to the cause of PFPS. For e.g. a person with flat feet causes the knee position to sit/twist inwards thus impeding on proper alignment of the patella. Tight structures surrounding the knee cap including the ITB and lateral retinaculum will also cause the patella to pull laterally.
Research has shown that conservative treatment is effective for PFPS. A physiotherapy treatment program will be guided by the patients goals such as return to sport and other functional activities and will incorporate most of the following management strategies:
– In the acute phase of PFPS your Physiotherapist may recommend a period of rest
– Muscle re-training to strengthen the quadriceps, especially of the VMO, hamstrings and hip muscles
– Modalities such as taping is often an effective short-term solution to assist in aligning the patella
– Foot biomechanics will also be addressed and you may require orthotics if warranted
– Addressing tight structures with soft tissue massage will also assist in proper tracking of the patella