Patellofemoral pain occurs in the front of the knee. Approximately one-third of knee pain is related to the patellofemoral joint, writes Jay Lieberman in the "AAOS Comprehensive Orthopaedic Review." A clinician is able to generally diagnose the most common pathologies by taking a history, performing a physical examination and ordering the appropriate imaging and lab studies. Patellofemoral pain can result from a variety of pathologies, including fracture.
Patellofemoral Pain Syndrome (PFPS)
Patellofemoral pain syndrome (PFPS) is a common pathology leading to anterior knee pain. Drs. Fredericson and Yoon of Stanford University say that approximately 25 percent of sports knee injuries are related to PFPS. Although the actual cause of the pain is unknown, most clinicians, notes Waryasz and McDermott of Tufts University School of Medicine, believe the pain is due to maltracking of the patella during knee flexion and extension. Physical therapy is helpful in approximately two-thirds of patients. Pain can be unilateral or bilateral. Symptoms can occur going up or down stairs, walking, running, or sitting for long periods of time. According to Waryasz and McDermott, patellofemoral pain syndrome can occur to a variety of muscular and anatomic imbalances, at either the hip or knee joint, and, therefore, a prevention program aimed at creating balanced strength and flexibility at the hips and knees can help to possibly prevent symptoms.
Patellofemoral Osteoarthritis
Osteoarthritis can affect any joint in the body. The patellofemoral joint can develop arthritis over time, affecting either the patella or the femur on the articulating surface as the cartilage wears down. The cartilage that covers the bone can wear down, and there can eventually be bone rubbing on bone during range of motion of the joint. The pain from osteoarthritis does not necessarily correlate with the imaging findings. Findings on imaging may include osteophytes (extra bone growth), subchondral sclerosis (thickening noticed on x-ray), bony cysts and joint space narrowing. There have been innovations in recent years for patellofemoral replacements and total knee replacements, which doctors may use as treatment, once more conservative measures have failed.
Patellar Tendinitis
Patellar tendinitis is a common condition that causes tenderness directly over the patellar tendon, distal patella and tibial tuberosity (the site of insertion for the patellar tendon). It can be due to overuse or have an onset for no known reason. Patellar tendinitis is also known as jumper's knee, as it is common in basketball and volleyball players.
Bursitis
Bursitis is a condition where the small, fluid-filled pads that cushion bones, tendons and muscles near the joint become inflamed. Bursitis is typically due to overuse and repetitive motion. There are over 10 bursa that can become inflamed near the patellofemoral joint, including the pes anserine bursa and the prepatellar bursa. Treatment includes rehabilitation, nonsteroidal anti-inflammatories and, occasionally, steroid injections.
Rheumatoid Arthritis
Inflammatory arthritis refers to rheumatologic manifestations that can occur around any joint. Rheumatoid arthritis (RA) is a common cause of inflammation that can affect the knee joint, specifically, the patellofemoral joint. There is an autoimmune destruction of the joint aimed at the synovial tissue of the joint. RA can cause more than just joint manifestations. Laboratory testing can help with the diagnosis.
Patellar Dislocation/Subluxation
The patella can often be dislocated or partially dislocated (subluxation), leading to a painful condition. Dislocation/subluxation can be acute or chronic and recurring. The medial patellofemoral ligament is a restraint to lateral dislocation and is often torn or stretched. There is an increased risk of long-term osteoarthritis in patients who have had a dislocation or subluxation episode.
Fracture
Fractures can occur to either the patella, tibia or femur, causing anterior knee pain. A simple x-ray can help to diagnose a fracture if there is an acute trauma. Patellar fracture can occur in a variety of patterns that require different treatments, ranging from simple immobilization to surgical repair.
References
- "Current Diagnosis and Treatment in Orthopaedics"; Harry Skinner; 2006
- "AAOS Comprehensive Orthopaedic Review"; Jay Lieberman; 2009
- Dynamic Medicine: Patellofemoral Pain Syndrome (PFPS)
- Am J Phys Med and Rehab: Physical Examination and Patellofemoral Pain Syndrome
