Pain below the knee is common, affecting individuals across various activity levels. This complex region houses numerous bones, muscles, tendons, and ligaments that facilitate movement and support body weight. Discomfort can arise from diverse origins, including repetitive strain from physical activities or underlying medical conditions.
Key Structures Below the Knee
The lower leg, extending from the knee to the ankle, contains two main long bones: the tibia and the fibula. The tibia, often called the shin bone, is the larger, weight-bearing bone on the front and inner side of the leg. The fibula runs parallel to the tibia on the outer side, contributing to ankle stability rather than significant weight bearing. These bones provide the framework for various muscles.
Lower leg muscles are divided into compartments. The calf muscles (gastrocnemius and soleus) at the back of the leg point the toes downward and propel the body forward. Muscles on the front, like the tibialis anterior, lift the foot. Tendons connect these muscles to bone, including the patellar tendon (kneecap to tibia) and the Achilles tendon (calf muscles to heel bone). The pes anserine tendons, from three hamstring muscles, insert on the inner side of the tibia below the knee.
Pain in the Front and Side of Your Lower Leg
Pain experienced along the front or outer side of the lower leg often stems from conditions related to overuse or repetitive stress.
Medial tibial stress syndrome, or shin splints, is a common issue. It causes diffuse pain along the inner tibia, usually in the lower half of the shin. It develops in runners or those who abruptly increase activity, often due to repetitive impact or inadequate footwear.
Patellar tendinopathy, or “jumper’s knee,” causes pain directly below the kneecap where the patellar tendon attaches to the tibia. It results from repetitive stress and micro-tears within the patellar tendon, common in athletes requiring frequent jumping (e.g., basketball, volleyball). Pain worsens with activities like jumping, running, or squatting.
Osgood-Schlatter disease primarily affects adolescents, causing pain and swelling just below the kneecap at the tibial tuberosity, where the patellar tendon attaches. It is an inflammation of the growth plate at this site, exacerbated by repetitive quadriceps traction during growth spurts. A tender lump often develops, with pain intensifying during physical activity.
Stress fractures of the tibia or fibula are tiny bone cracks from repetitive mechanical stress without adequate repair time. Pain is localized to a specific spot, worsening with activity and improving with rest. Common in long-distance runners or military recruits, they link to sudden training load increases, surface changes, or insufficient bone density.
Pain in the Back and Inner Lower Leg
Discomfort localized to the back or inner aspect of the lower leg, below the knee, can indicate several distinct conditions.
A calf muscle strain involves tearing muscle fibers in the gastrocnemius or soleus muscles at the back of the lower leg. It causes sudden, sharp calf pain, often with bruising, swelling, and difficulty bearing weight. It occurs during activities involving sudden acceleration or forceful push-offs.
Pes anserine bursitis is inflammation of the bursa, a small fluid-filled sac, on the inner side of the knee, about two inches below the joint line. It causes pain and tenderness over this inner knee area, often worsening with activity or at night. It associates with overuse, tight hamstrings, obesity, or knee osteoarthritis.
A Baker’s cyst, also known as a popliteal cyst, is a fluid-filled sac that forms behind the knee. Though behind the knee joint, it can cause fullness, pressure, or pain radiating into the upper calf. These cysts typically result from underlying knee joint problems, such as arthritis or meniscus tears, which generate excess synovial fluid. Discomfort often increases with full knee extension or flexion.
Achilles tendinopathy affects the Achilles tendon, connecting the calf muscles to the heel bone, though pain can be felt higher in the lower calf. It involves degeneration and inflammation within the tendon, causing pain, stiffness, and tenderness along its length. Symptoms worsen in the morning or after inactivity, aggravated by repetitive activities like running or jumping.
When Pain Below the Knee is Serious
While many causes of lower leg pain are benign, certain symptoms warrant immediate medical evaluation due to their serious nature.
Deep vein thrombosis (DVT) is a blood clot in a deep vein, most commonly in the calf or thigh. Symptoms include throbbing pain, swelling, warmth, and reddish or darkened skin, typically in one leg. It is serious because the clot can break loose and travel to the lungs, causing a life-threatening pulmonary embolism.
Compartment syndrome is a serious condition where pressure within lower leg muscle compartments builds to dangerous levels. Acute compartment syndrome is a medical emergency, often from trauma, causing severe, unrelenting pain disproportionate to the injury, with tightness, numbness, or tingling. Chronic compartment syndrome, often exercise-induced, presents similar symptoms that resolve with rest.
Nerve entrapment or compression, such as peroneal nerve entrapment, can cause pain, numbness, or weakness in the lower leg and foot. The peroneal nerve, near the fibula head, can be compressed by trauma, tight casts, or prolonged pressure, leading to foot drop. Persistent numbness, tingling, or muscle weakness requires professional investigation.
Seek medical attention for lower leg pain if you experience sudden, severe pain, inability to bear weight, or significant swelling that does not subside. Other red flag symptoms include numbness, tingling, or weakness in the foot or toes; signs of infection like fever, spreading redness, or warmth; and pain that worsens or does not improve with rest. This information serves as a guide and does not replace professional medical advice or diagnosis.