Knee pain can significantly affect your ability to move around, particularly when you need to climb stairs. Pain in the front of your knee is typically related to your patellofemoral joint, where your kneecap sits in front of your thigh bone. Stair climbing increases compression at this joint. "Patellofemoral pain syndrome" is a term used to describe different conditions that commonly cause pain in the front of your knee. See your doctor to accurately diagnose your knee pain.
Kneecap Tracking
Your kneecap is embedded in a thick quadriceps tendon that attaches to your lower leg bone. The kneecap glides along a groove in your thigh bone as you bend and straighten your knee, applying tension to this tendon. Sometimes the kneecap moves out of the groove -- a painful condition called patellar tracking disorder. This can be caused by muscle weakness on one side of your thigh muscles, causing the kneecap to be pulled toward the stronger side.
Your body structure may also contribute to front knee pain when you climb stairs. The angle of pull on your quadriceps tendon is impacted by the alignment of your hips, thigh bone and lower leg bone. This alignment, called the "Q-angle," is typically larger in women than men. A larger Q-angle can pull your kneecap outward, causing it to slide out of the groove as you move your knee. Flat arches in your feet can also cause your kneecap to track improperly. Over time, this can cause pain with daily activities such as stair climbing. It typically subsides with rest.
Tendon Damage
Front knee pain while climbing stairs can be caused by irritation of your patellar tendon. Overuse of your quad muscles in the front of your thigh can cause inflammation of this tendon. These muscles straighten your knee, and keep it from bending too quickly during high-impact activities such as jumping. Patellar tendon overuse is common in athletes and military recruits. Repetitive strain on your patellar tendon causes inflammation, leading to pain and possibly swelling in the front of your knee. Over time, micro-tears can develop in the fibers of your tendon. This type of pain may occur quickly with new physical activity or gradually worsen as activity intensifies, and usually decreases with rest.
Kneecap Arthritis
Cartilage provides padding between bones' surfaces in healthy joints. Arthritis breaks down joint surfaces, causing pain with activity. Chondromalacia patella is a condition that develops as cartilage under your kneecap wears away. Symptoms typically develop over time. Dull, aching pain may be present at rest, while activities may cause sharp pain in the front of your knee. Stair climbing is a particularly aggravating activity with kneecap arthritis.
Osgood-Schlatter Disease
Osgood-Schlatter disease is a condition that affects growing children. This is most common in athletes who run and jump repeatedly. The patellar tendon begins to pull away from the bone due to this repetitive stress, and a large bump develops on the front of the knee, below the kneecap. Pain occurs with activity and decreases with rest. This condition resolves when the child stops growing, but the bony lump is permanent.
Note – This information has been taken from different internet sources.