Dislocated Knee - Patella Malalignment/Dislocation
The normal patella should track in the groove of the femur in a relatively straight manner, but sometimes the patella can slip out of place due to injury or congenital abnormalities in the shape of the knee.
This slippage may be very minor, or you may actually see that the patella is in the wrong position. If it slips all the way out of position this is called dislocation. If it only partially slips this is called subluxation.
Patella Realignment
Tibial Tuberosity Transfer with Lateral Release
The knee is made of three bones, the kneecap (patella), the shin bone (tibia) and thigh bone (femur). To make the movement smooth and pain free, these bones are covered with a layer of cartilage on their contact surfaces. The patella is also held in place by a broad tendon and one of the largest muscles in the body. This tendon mechanism connects the thigh muscle (quadriceps) to the shin bone (tibia) just below the knee joint. The patella and patella tendon together with the quadriceps muscle are responsible for the ability to stand, walk, jump, kneel and navigate stairs. To do all of this, a normal functioning kneecap slides up and down a groove on the end of the femur as the knee bends. For stability, this groove (the patellofemoral articulation) is designed to guide the kneecap down the center of the knee joint and slide evenly within the groove. The groove varies in people, sometimes it is steep and in other people it is very shallow. The tendon can also be aligned to the inner or outer side of the knee. The ligaments on either side of the knee cap can be loose of tight. When the grove is shallow or the tendon is mal-aligned, the kneecap can jump over the edge of its groove. Occasionally this is worsened by a direct result of trauma or a sports injury. An injury of this type can weaken the soft tissue support for the kneecap in its groove and subluxation or dislocation can occur more easily. When this happens frequently, it causes pain and disability. In recurrent patella subluxation the patient complains of a sensation of knee cap dislocation or “giving way.” Sometimes the feeling is difficult to describe and it can be confusing since other knee problems (like ligament or cartilage tears) also cause the sense of giving way. Physical examination of the knee with the findings of pain along the outside or under the kneecap or mal-tracking of the patella with squatting bending or stairs can help make the correct diagnosis. Treatment: In those patients where tightness of one part of the tendon over powers the other the patella tends to subluxate toward the tight side (it is almost always lateral tightness). When the diagnosis is clear, one type of surgery to improve alignment and stability involves using the arthroscopy to release the tight tissue on the outer side of the patella (a “lateral release.”) Releasing the tighter side often decreases the subluxation, reduces the pressure on the cartilage, decreases pain and improves function. Other patients have both tightness on the outer side of the knee and a mal-position of the tibial insertion of the patella tendon. The tendon mal-alignment also pulls the knee cap to one side. The distance between the center of the grove and the location of the tendon insertion on the tibia helps us to decide if this is an important factor in this problem. In those cases, moving the bony attachment point is the best way to control the kneecap’s position in its groove. In the tibia tubercle realignment procedure (also known as a tibia tubercle transfer), the location at which the tendon attaches to the tibial tubercle (the bony prominence below the patella) is moved forward and toward the inner side. It is then held in place with two screws. The screws hold the bone in place while it heals and help the patient become active sooner. The procedure is done in a special way to avoid some of the pitfalls of older methods used to correct this problem. The end effect of this procedure is to hold the patella within its normal grove, correcting the tendency for it to slide out of position to the outer or lateral side with a quicker recovery than traditional corrections. Dr. Reznik does this as a minimally invasive procedure using the arthroscope to prepare the knee and a smaller incision for the movement of the bone attachment. He does this as an outpatient procedure avoiding a hospital stay and allowing the patient to recover in the comfort of their own home. Recovery Plan: Below are helpful tips when planning surgery and the recovery at home. Pain Control: Take medication as prescribed by Dr Reznik. Please call our office with any questions regarding your medication. Use ice machine as directed and elevate leg above heart level. This will decrease swelling and help with a common complaint of “throbbing” pain associated with a tibial tuberosity, lateral release procedure. Immobilizer: You will need a knee immobilizer for 2-3 weeks to protect the knee. When the knee is more stable you will change into a knee hinge brace. Most patients can start full weight bearing as symptoms allow after 3 weeks while wearing the hinge brace. Diet: You may resume a regular diet when you return home. Most patients start with tea or broth adding crackers or toast, then a non-spicy sandwich. If you become nauseated, check to see if one of your medications is upsetting your stomach, most narcotics can. If your stomach feels acidy, try Tums, Zantac or Pepcid AC to settle it and drink some clear liquids. Avoid grapefruit, tomato and orange juice since they have a high acid content. Lungs: After surgery you are encouraged to deep breathe and cough frequently (at lease 3-4 times per day). This will reduce mucous from building up in your lungs, and will reduce the small risk of developing a post anesthetic pneumonia even further. Dressing and Bleeding: After a tibial tuberosity transfer and a lateral release, a moderate to amount of blood tinged drainage (mostly Novocain used in the knee before during the procedure for post op pain control) is common. Sometimes this is brought on by the first few times the knee is bent or after the first few steps at home. You may need to reinforce the dressing during the first 24 – 48 hours. Applying pressure to area will help reduce this drainage. Important Precautions with Ice Machine Use- Always keep a thin gauze or cloth between the skin and the cooling pad. Do not allow the pad to contact the skin directly as this may cause frostbite.
- After the first dressing change, inspect the skin regularly and notify our office staff if there are any sign of changes in skin appearance or increasing redness.
- Change the ice and water when you are unable to maintain a temperature of 48-52 degrees. Lower temperatures may damage the skin.