The lateral view of the knee is a side radiographic projection that visualizes the patella, femoral and tibial condyles, joint space, and adjacent soft tissues. Typically taken with slight knee flexion and the X‑ray beam perpendicular to the joint, it detects fractures, dislocations, joint effusion, osteochondral injuries, and assesses alignment. It complements anteroposterior and skyline views for comprehensive evaluation.

For a lateral knee X‑ray the central ray is typically directed 5–7° cephalad, with the knee flexed about 20–30° (mediolateral projection). This angle helps superimpose the femoral condyles and open the joint space; it may be increased slightly (about 10°) for larger thighs or to achieve proper alignment.

A lateral knee X‑ray can show signs of osteoarthritis — joint space loss, osteophytes, subchondral sclerosis or cysts — and helps assess bone alignment. However, X‑rays show later bony changes and give limited detail on cartilage or soft tissue, so early arthritis or inflammatory causes may be missed. Clinical assessment and, if needed, weight‑bearing views or MRI help confirm diagnosis.

A 3‑view knee X‑ray includes anteroposterior (AP), lateral, and a skyline (axial/patellar) view. Together they show bone alignment, joint spaces, fractures, patellar position and the patellofemoral joint, and signs of osteoarthritis or effusion. These complementary projections improve detection of subtle fractures, dislocations and cartilage space narrowing, guiding diagnosis and management after trauma or persistent knee pain.

A lateral knee problem refers to pain or dysfunction on the outer side of the knee. Common causes include iliotibial band friction, lateral collateral ligament injury, lateral meniscal tear, bursitis or osteoarthritis. Symptoms are localized pain, swelling, catching, instability or reduced weight‑bearing. Diagnosis uses clinical exam and imaging. Treatment ranges from rest, physiotherapy, anti‑inflammatories and injections to surgery for severe structural damage.

A lateral knee radiograph is reliable for assessing bony alignment, dislocations, obvious fractures, joint effusion, and patellar positioning. However it can miss occult or non-displaced fractures and cannot reliably evaluate cartilage, cruciate ligaments, or menisci. If clinical suspicion persists despite a normal lateral view, CT is better for subtle bone injuries and MRI is superior for soft-tissue pathology.