Accident, injury, and overuse are some of the common root causes of pain on the side of the knee. Resulting conditions affecting the ligaments, meniscus, cartilage, and additional structural aspects of the knee can lead to pain along the inside or outside of the joint. Identification and proper treatment of the condition can help reduce and limit knee pain.
Sudden jolts to the side of the knee, a fall resulting in a twisting action, or disease can lead to damage to the collateral ligaments supporting the knee joint. Collateral ligaments, including the lateral collateral ligament (LCL) and the medial collateral ligament (MCL), can become torn or pulled, resulting in pain. Diseases related to the ligaments, such as Pellegrini-Stieda syndrome, which affects the medial collateral ligament, can lead to pain on the side of the knee as well.
The shearing action from a sharp turn often results in damage to the knee’s menisci. This cartilaginous tissue helps cushion the knee joint, and can become torn during injury or wear out over time. Injury to the menisci of the knee can result in inflammation and pain.
Arthritic conditions, such as osteoarthritis and rheumatoid arthritis, can result in pain across the entire knee, including along the sides. Osteoarthritis is a result of deteriorating cartilage, while rheumatoid arthritis is a result of inflammation within the joint. Some cases may be so severe that a total knee replacement is required.
Overuse injuries include those affecting the iliotibial band on the outside of the knee. Often seen in runners and other athletes who change training regimens, iliotibial band syndrome may also cause pain along the outside of the thigh. In addition to the inflammation of the iliotibial band itself, iliotibial band syndrome can cause inflammation of the bursa within the knee joint, resulting in pain on the side of the knee.
Beyond the common causes of pain along the inside or outside of the knee, several rare conditions may cause pain on the side of the knee. Infection of the bone is possible and would present with other symptoms, such as fever and chills. Tumors within the joint are also rare, but possible.
Bearing weight on the knee can exacerbate inner and outer knee pain. A treatment regimen including ice, rest, and elevation can help decrease pain and spur healing. Other treatment options include immobilization devices, such as braces and splints. Surgery may be necessary in the case of serious injuries.