In case of a luxating patella, the patella (kneecap) slides out of its normal position. The luxating patella is also often called patella dislocation or kneecap dislocation. When a kneecap dislocates, bones, cartilage and ligaments of the knee can be damaged. A subluxation of the patella is given if the patella slides out but returns quickly.
A luxating patella often causes strong, stinging, suddenly emerging pain accompanied by a swelling of the knee. People often realize their kneecap dislocating and the knee or lower leg sagging making the joint unstable. It is then no longer able to withstand stress, and the kneecap is very sensitive to pressure. Only by watching the knee, the kneecap dislocation is visible.
Symptoms of the luxating patella in short:
A luxating patella can have several causes. One cause may be an accident forcing the kneecap to dislocate. This can happen during falling down or being hit against the knee. If an external force causes patella dislocation, it is called traumatic patella dislocation. Even if the patella returns to its normal position, often instability is the result that makes recurrent patella dislocations possible.
Kneecap dislocation can also occur without any accident. This so-called habitual patella dislocation is probably caused by congenital deformations or malposture of kneecaps, legs (bowlegs or knock-knees), the groove of the patella or of the ligaments often in combination with a muscular imbalance of the thighs.
A luxating patella is visible with the naked eye since the patella has clearly slided out. But it is also possible that the kneecap slides out and quickly slides back (subluxating patella). In any case, a comprehensive orthopedic examination is necessary to examine the damage of the knee.
Often imaging procedures like MRI are used to differentiate different diseases that may cause similar or the same symptoms like the luxating patella. The best method to differentiate between different injuries is MRI.MRI enables us to visualize very different structures during one examination like muscles, ligaments, tendons, cartilage and bones. If it is necessary, we do also apply a well-tolerated contrast agent to improve the visibility of certain structures.
A luxating patella can be treated conservatively or surgically. If patients are suffering from a patella dislocation that has caused only minor damage in adjacent parts of the knee, the kneecap is manually adjusted by a physician until it has reached its normal position while stretching the leg. If conservative means like physiotherapy and strengthening of leg muscles or wearing a special bandage are not sufficient, or if it is a severe or habitual patella dislocation with major damage of adjacent structures, knee surgery is often inevitable.