Patellofemoral pain syndrome (PFPS) is a painful condition of knee where the pain is felt around and behind knee cap and aggravated by at least one of the following activities like, running, climbing stairs or squatting. Also complains of knee stiffness following prolong sitting in knee flexed position. It is a common cause of knee pain in adolescent and adult younger than 60 years. It is a very common overuse injury of knee cap.
Knee cap forms a joint named patellofemoral with trochlea of femur. It acts a lever for quadriceps muscle excursion and reduce energy requirement for this muscle in knee extension and deceleration. The joint is stabilized by quadriceps muscle specially by its vastus medialis portion, patellar tendon, MPFL retinaculum and other bands around it.
Female sex and activity like running, jogging, squatting and frequent use of stairs are the established risk factor for developing patellofemoral pain syndrome. Patellar instability plays a major role in developing PFPS. Quadriceps weakness, dynamic valgus of knee, where knee collapse medially from excessive valgus on weight bearing, foot deformities like flatfoot, fore foot eversion and pronation deformity also contribute in PFPS development. Foot deformity lead to internal rotation of tibia and contributes to development of dynamic valgus of knee. Dynamic valgus increases lateral force on patella thus contributes to patellar maltracking. Dynamic valgus is very common in female athlete so PFPS is also common.
Diagnosis of PFPS is purely clinical. Complain of pain during squatting is the most sensitive finding. Fluid collection in knee joint, redness and increase temperature at knee are never associated with patellofemoral pain syndrome. Imaging are done for exclusion of other cause of anterior knee pain like chondromalacia patellae, trauma, infection or other cause of anterior knee pain where clinically suspect. Physical examination to elicit patellofemoral pain like clerk test patellar tilt test help in diagnosis. Examination of gait, posture, foot deformity, wear pattern of footwear, quadriceps power, hamstring muscle flexibility all can give clue in finding contributory factor of PFPS development.
Most common other diagnosis along with PFPS are chondromalacia patellae and patellofemoral arthritis others are traumatic injury of patellar cartilage, trochlear dysplasia, patellofemoral arthritis, Hoffa’s syndrome, quadriceps tendinopathy, patellar tendinopathy plica syndrome, iliotibial band syndrome etc.
Physical therapy is the one and only solution for patellofemoral pain syndrome. Analgesics and other measures are recommended for short term pain relief. Kinesiotaping of patella helps in symptomatic relief during acute phase along with analgesics. Corrective foot orthotics are recommended along with physical therapy to improve gait and kinematics of knee. Knee braces does not help much and there is no role of surgical intervention. Non resolving of symptoms beyond 6-8 weeks render imaging test like x-ray or MRI to find other cause of patellofemoral pain.