There are several reasons someone might present with knee pain. One of the many reasons is a faulty patellofemoral joint. The patella is the anatomical name for the kneecap and the patellofemoral joint is the name of joint formed by the junction of kneecap and underlying femur or thigh bone. It is not a synovial joint like that of the hip or the underlying knee joint, but a sliding joint. Its function is to provide increased leverage for greater force and power of the quadriceps muscle as it extends the knee as well as protection of the knee against compressive forces. For clients with knee pain the patellofemoral joint must be evaluated properly to find the best treatment plan. I would like to address three pathologies of the patellofemoral joint that could be the cause of someone’s knee pain.
Injury to the Infrapatellar fat pad
The infrapatellar fat pad is a fatty soft tissue that sits between the front part of synovial lining of the knee joint and the patellar tendon. Because of this location the fat pad can become wedged between the tibia and the patella especially with pressure on the kneecap as with chronic kneeling or a direct blow to the patella. These repetitive blows to the fatty tissue of the fat pad causes capillary hemorrhaging within the tissue and swelling. The compliant of pain is below the kneecap around the patellar ligament. The symptoms also might include stiffness, weakness and painful knee extension.
Patellofemoral Stress Syndrome
Abnormal tracking of the patella in the femoral or (trochlear) groove will lead to knee pain. There exists an anatomical groove in the femur bone in which the patella should slide along, called the femoral groove. Patellofemoral Stress Syndrome results from an excessive lateral departure of the patella in the femoral groove. This usually occurs because of some fault in either the lateral or medial structures that hold the kneecap in place. The client usually presents with tenderness along the lateral side of the patella, some slight swelling, a dull ache and usually cracking and popping sounds of the knee. Additionally, the patella will be painful or at least apprehensive when it is forced laterally. Treatment for patellofemoral stress syndrome must include proper evaluation of the medial and lateral structures that support and control the patellar position. Some of the structure that need to be evaluated include the muscle length of the hamstring and gastrocnemius, shortening of the lateral retinaculum, shortening of the iliotibial band, excessive pronation, medial quadriceps insufficiency and/or weakness, and strength of hip adductors. These are just a few of the examples that can cause a patellar tracking issue and should be evaluated be a trained eye.
If abnormal tracking of the patella in the femoral groove is not corrected early, then there is a probability it can lead to softening and deterioration of the articular cartilage on the back of the patella, termed chondromalacia. It is possible for some clients to develop chondromalacia that actually have good patella tracking, however poor tracking is the primary etiological factor. The client with chondromalacia presents with pain in the front of the knee while running, ascending and descending stairs and squatting. Additionally, there is mild reoccurring swelling around the kneecap and sometimes patients describe a sensation when bending or extending the knee. Moreover, sometimes the client will develop degenerative arthritis on the medial facet of the patella. Some authors have staged the progression of chondromalacia. Stage 1 defined as swelling and softening of the articular cartilage; Stage 2 defined as fissuring of the softened articular cartilage; and Stage 3 defined as deformation of the surface of the patella causing fragmentation of the soft tissue.
If you suspect you have a patellar femoral pain syndrome, getting it checked out sooner rather than later can prevent you from dealing with a more complex problem. It is wise to consult with a skilled physical therapist who can properly evaluate your specific problem and direct you to the most efficient and comprehensive treatment plan.