The patella is the largest sesamoid bone in the body. It has two articular surfaces with thick articular cartilage due to its heavy loads. The patella articulates with the femur and more specifically with the femoral trochlea – a kind of “groove” – creating the patellar knee joint. As long as the patella remains in the groove during flexion and extension, one can walk, run, sit and stand. When the patina slips out of the groove, joint pain and problems arise.
The patella connects the muscles in the front of the femur with the tibia. When bending and extending the knee, the patella is pulled up or down. As mentioned above, the femur has a notch or groove called the femoral trochlea. The patella articulates and moves through this groove. However, if this groove is shallow or uneven, the patella may slip, resulting in dislocation. Even a direct blow can cause dislocation of the patella.
The knee is blocked and can no longer support body weight
There is pain in the front of the knee increased with activity
Pain in seated position
Cracking during movement
During the physical examination, the orthopedist asks the patient to walk, stretch and bend his knee. A careful examination of the area around the patella follows, as well as measurements for its alignment.
Radiographs: They are useful for assessing the patellar-femoral anatomy (how they fit together) and to exclude other lesions.
If the patella is dislocated, the first step is to bring it back to place. Sometimes the reset is performed automatically. Other times the orthopedist must apply a gentle force to push the patella into place.
Patellar dislocation can cause damage to the articular surface of the patella and femur leading to additional pain and osteoarthritis. Arthroscopic surgery can correct this condition.
If the patella is partially dislocated, it can be preserved with special exercises and splints. The exercises will help strengthen the femoral muscles, so that the patella remains aligned.
Cycling is often recommended as part of physiotherapy. In addition, special splints can help the patient to heal. The goal is to get the patient back to their daily activities within one to three months.
Surgery may be necessary in cases where the patella is unstable. With surgery, the patella is aligned either by repairing and reinforcing the patellotibial ligaments or by releasing the ligaments that pull the patella out of position.