THE PATELLOFEMORAL JOINT
In general, the greater the muscle force, the greater the joint reaction force. In PF joint, the quadriceps muscle force increases with knee flexion. During relaxed upright standing; minimal quadriceps muscle force are required to counterbalance the small flexion moments about the PF joint. Level walking requires little knee flexion, the reaction force was low. During knee flexion; the centre of gravity shifts farther from the centre of rotation. Hence increase in flexion is counterbalanced by the quads muscle force. As the quads muscle force rises PF joint reaction force also rises. In the middle of stance phase when flexion is the greatest, the PF reaction forces value reaches it’s peak value is one half the body weight. During stairs climbing and descent, at the point when knee flexion reached a maximum of about 60 degrees, the peak value for joint reaction force equaled 3.3 times the body weight.
When knee is extended, the lower part of patella rests against the femur. As the knee is flexed to 90 degrees, the contact surface between the two surface between the patella. This increase in contact surface with knee flexion to some extent compensate for the large PF joint force. Patients with patellofemoral joint derangements experience increased pain when performing activities that requires large amount of knee flexion.
The patellofemoral joint (PFJ) is one compartment of the knee that is frequently affected by osteoarthritis (OA) and is a potent source of OA symptoms.
Treatment of PFJ consists of (i) quadriceps muscle retraining; (ii) quadriceps and hip muscle strengthening; (iii) patellar taping; (iv) manual PFJ and soft tissue mobilisation; and (v) OA education.
Resistance and dosage of exercises are tailored by participant's functional level and clinical state.
* we have not mentioned about the bio-physical modalities that one may chose while treating patients a in a OPD set up.