Facts on File Encyclopedia of Health and Medicine

knee injuries 331

COMMON KNEE INJURIES

Injury Common Causes Key Symptoms
anterior cruciate LIGAMENT(ACL) sudden twisting of the knee or blow to the pop or snap felt and heard
sprain front of the knee swelling
mild PAIN
“loose” feeling to knee
inability to bear weight on the leg

hyperextension direct blow to the front of the knee pain with hyperextension
soreness after knee returns to normal
extension

lateral collateral ligament (LCL) impact to the inside of the knee pain
sprain pop or snap felt and heard
knee buckles to the outside

medial collateral ligament (MCL) impact to the outside of the knee pain
sprain pop or snap felt and heard
knee buckles to the inside

meniscus tear sudden rotation of the upper body with the pain
foot planted clicking or locking within the knee
instability of the knee

patella DISLOCATION impact to the side of the patella pain
fall that jars the side of the patella patella obviously out of position, usually
to the side of the knee
inability to bend the knee

patella FRACTURE sharp blow to the patella severe pain and swelling
inability to move the knee or bear weight
on the leg

patellar TENDONrupture stumbling in an attempt to avoid a fall pain
landing after a jump from considerable height tenderness to touch at point of rupture
difficulty bending or extending the lower
leg
displaced patella

PATELLOFEMORAL SYNDROME long-term repetitious movement of the knees pain with bending or extending the knee
such as with running and bicycling
poor conditioning

posterior cruciate ligament (PCL) impact or blow to the front of the knee pop or snap felt and heard
sprain swelling
mild pain
“loose” feeling to knee
inability to bear weight on the leg