A knee lateral view X-ray is a side-view radiograph taken with the knee slightly flexed to show joint alignment, the patellofemoral relationship, femur, tibia, fibula, and surrounding soft-tissue shadows. It helps detect fractures, dislocations, joint-space narrowing, loose bodies, effusions, and osteoarthritic changes. It's commonly used alongside an AP (front) view for comprehensive assessment of trauma, pain, or degenerative disease.

Position patient lateral recumbent with the affected knee closest to the detector, or supine with the knee rolled onto its side. Flex the knee about 20–30° so the patella is perpendicular to the image receptor and femoral condyles are superimposed. Center the central ray to the knee joint (≈1 cm distal to the medial femoral condyle), perpendicular to the receptor. Include distal femur and proximal tibia/fibula; shield gonads.

A lateral view of the knee joint space is a side X‑ray projection showing the femur, tibia and patella in profile to assess joint space width, articular cartilage loss, osteophytes, fractures and effusion. It evaluates tibiofemoral and patellofemoral alignment, detects fluid in the suprapatellar recess, and helps quantify joint space narrowing for osteoarthritis or trauma assessment.

Clinical criteria suggesting lateral knee pathology include localized lateral joint‑line or fibular‑head tenderness, swelling/effusion, mechanical symptoms (locking/catching), pain on weight‑bearing, reduced range of motion, and inability to bear weight. Specific exam findings: increased laxity with varus‑stress testing (LCL injury) and pain or clicking with external‑rotation McMurray or Thessaly tests (lateral meniscal tear).

A lateral view on an X‑ray is an image taken from the side, with the X‑ray beam passing laterally through the body to a detector on the opposite side. It presents structures in profile, reducing overlap seen on frontal views and helping assess depth, displacement, or anterior–posterior relationships. It’s commonly used for chest, spine and joint evaluation with the patient standing, sitting, or lying on their side.

A lateral knee X-ray can show typical osteoarthritis findings — joint‑space narrowing, osteophytes, subchondral sclerosis or cysts, and bone‑on‑bone contact, often in the patellofemoral or tibiofemoral compartments. X‑rays detect bony changes, so early cartilage loss or soft‑tissue problems may be missed. If symptoms persist despite normal X‑rays, clinical review or MRI may be needed.