Knee Sprains

• A sprain on your knees means you have stretched or torn one or more knee ligaments. Its causes are twisting and hyperflexion of the knees. If your thigh muscles are weak, this could lead to knee sprains, too. Symptoms of knee sprains are swelling, feeling loose or unstable around the knees, pain with movement and a snapping sound in the knee. You may also find straightening the leg difficult and you cannot seem to walk without limping. 
  
  

Knee Strains

• Strains are another common form of knee injury caused by overuse. They can cause you pain, swelling and bruises around the injured area. They are not as severe as a knee sprain.
  
  

Tendonitis

• Tendonitis is an inflammation involving the tendon. The sheath around the tendon may be inflamed and painful. It is caused by overuse. You know if you have tendonitis if you feel pain or tenderness when you walk and extend or lift your leg.
  
  

Swelling

• Excessive fluid can accumulate in the membrane surrounding the kneecap. This condition is caused by overuse.
  
  

Dislocation of the Kneecap

• Twisting or torsion on the knee can result in kneecap slipping out of the groove on the thighbone. The common signs to watch for are a popping and the feeling that the kneecap is out of place. If the kneecap is dislocated, seek medical attention at once.
  
  

Fractures

• Jumping injuries can include fracture of the surface of the tibia (a leg bone). People with osteoporosis or weak bones can easily have fractures involving the knee bones during an exercise. Those who do not have weak bones still have the possibility of tiny fractures in the bone.
  
  

Warning

• Your knee can only take a certain amount of stress. If you have been putting a lot of stress to it and push it to its limit, chances are you will get knee injuries. Exercises can help you to tone and build muscle. However, if you overdo it you could injure your knees and suffer an excruciating pain for days. If you continue to have knee problems you may need to consult with your doctor or physical therapist.