OVERUSE SYNDROMES
Overuse syndromes are caused by repetitive trauma to the knee over a period of time, which leads to peripatelar pain and includes tendonitis of the patellar tendon and chondromalacia of the patella.
PATELLOFEMORAL DYSFUNCTION
Patellofemoral pain is a common complaint of baseball players and often occurs after repetitive activity, such as stair climbing, prolonged squatting, sprinting, weight training, and other activities that increase patellofemoral forces. Of all the joints in the human body, the patellofemoral joint is subjected to the highest forces. In order to resist these high contact stresses the articular cartilage of the patella is also the thickest in the human body. Patellofemoral pressures are the highest between 60˚ and 90˚ of flexion. At flexion angles >90˚, tendofemoral contact plays an important role in reducing patellofemoral contact pressures. Because of the delicate balance between enormous joint reaction forces and contact area, any imbalance will lead to aberrant loading of the patella with resulting symptoms.
The exact reason for pain is unknown, but it may be due to repetitive microtrauma, which leads to chondromalacia of the patella and or trochlear groove. Inappropriate patellofemoral articular balance from malalignment, patellofemoral incongruency, or dynamic imbalance, such as a weak vastus medialis oblique, may predispose one to chondromalacia. In addition, mechanical imbalalance of the foot and ankle, such as hyperpronation of the foot during foot strike may predispose the patella to maltrackingand subsequent symptoms.
TREATMENT
Initial treatment is conservative and emphasizes reduction of activity with quadriceps and hamstring flexibility and strengthening. If a lower extremity imbalance exist, shoe orthotic inlays with a medial heel wedge and arch support may be needed. Long arc exercises, such as forceful knee extensions from a hyperflexed position, will aggravate the condition and should be avoided. Quadriceps strengthening includes quadriceps setting, straight leg raises, and short arc extensions avoiding the terminal 30˚ of extension because of the high patellofemoral contact pressures. Iso-kinetic exercises that impose high loads on the patellofemoral joint should be avoided.
