Knee Joint
The knee is a hinged joint and is comprised of several structures. The femur (thigh bone - the largest bone in your body) extends from the hip to the knee joint. The tibia (shin bone - lower leg bone) connects to the knee joint also, and this area is covered by the patella (kneecap). Articular cartilage covers the bone ends of the femur and the tibia and assists it in allowing for a gliding motion in the joint.The meniscii (lateral and medial meniscus) make up a “C” shaped cartilage that forms an actual cushion inside the joint, thus providing shock absorption. The bones are tethered, or bound together, by supportive ligaments (anterior cruciate, posterior cruciate). Surrounding muscles help move the joint, decrease stress to the joint, and provide additional support. Support and stability in the knee are provided by its four ligaments, which are as follows:
The fibrocartilaginous meniscii of the knee are firmly attached to the tibia anteriorly and posteriorly, but are only loosely attached peripherally. During normal knee movement, they tend to move slightly inward or outward. Normal knee movement consists of a combination of movements (rotation, extension and flexion). These movements are controlled by the ligaments of the knee and by the meniscii, which also aid in shock absorption. Damage to the knee, such as a torn medial meniscus, can prevent normal rotation of the joint. The meniscii serve several purposes which include the control of normal knee motion.
Meniscal tears are the most common of all knee injuries, but the characteristics of each tear are variable. Generally, patients present with a tear of the medial (inside) meniscus, and the history of the injury includes a twisting fall while in a weight-bearing position on their feet. A patient’s description of the injury may include a “popping” sensation, followed by severe pain on the medial (inside) portion of the knee.
If a patient is seen several days to several weeks following the injury, the patient often discusses a sensation of the knee “locking up” or “giving way” and reports that it may be difficult to walk up or down stairs, and that it is difficult to squat.
To assess the damage in the knee, a physician will usually order an x-ray (known as a “plain film”) to rule out injuries in addition to the meniscal tear.
If the meniscal tear is acute, knee immobilization and the dedicated use of ice to decrease edema significantly, will be the treatment of choice. A meniscal tear that presents after the edema has dissipated will benefit from improving muscle tone in the extensor mechanisms of the leg. Most notably, this would include the quadriceps group.
Arthroscopic surgery can be performed on the meniscus with success and most patients can begin resumption of normal activities within 3-6 weeks.
A subluxed patella is more difficult to diagnose. Generally, the patella dislocates laterally, but this can be discerned on x-ray.
A “skyline” or “sunrise” x-ray view can give a physician a good idea of displacement, if any. Clinically, a patient will present with medial knee pain, swelling and/or a description of the knee “giving way.” Sometimes, the patella may appear higher than normal when the knee is flexed (bent). This condition is known as patella alta.
Immobilization of an acutely subluxed patella will run a 4-6 week course concurrently with the use of cryotherapy (ice) to control edema and pain. Later, a course of therapy emphasizing strengthening of the quadriceps group will generally be prescribed.
Strengthening of this area will greatly aid in decreasing future susceptibility to dislocations.
If, however, recurrent dislocations do occur, surgery may become an option. A variety of procedures may be considered in an effort to realign the patella and prevent further episodes of dislocation.
