Type: Clinical photographs illustrating habitual patellar dislocation during knee flexion. Anatomical Region: Left knee joint. Description: A series of three monochrome clinical images (A, B, and C) demonstrating the progression of patellar tracking as the knee moves from extension into flexion. Image A shows the knee in extension, where the patella maintains a seemingly normal anatomical alignment within the trochlear groove. Image B captures the knee at approximately 90 degrees of flexion, revealing a clear lateral subluxation of the patella. Image C shows the knee at 120 degrees of flexion, where the patella is significantly dislocated laterally, creating a prominent soft tissue protrusion on the lateral aspect of the knee and an abnormal joint contour. Educational Focus: This series demonstrates the clinical manifestation of flexion-dependent patellar instability or habitual dislocation, highlighting how dynamic physical examination is essential when static extension views appear normal. Clinical Relevance: Useful for diagnosing patellofemoral tracking disorders, medial parapatellar instability, or high sulcus angles.

This composite of two clinical photographs illustrates dynamic patellar instability in a patient with a history of total knee arthroplasty (TKA). Image 'a' shows the left knee in a state of full extension. In this position, the patella (highlighted by a black circle) appears reduced and centered within the trochlear groove. Image 'b' demonstrates the same knee during flexion, where the patella (highlighted by a black circle) exhibits a clear lateral dislocation, moving out of its normal anatomical alignment toward the lateral aspect of the joint. Long surgical scars are visible on the anterior aspect of the knee and proximal tibia in both views, consistent with previous orthopedic procedures. Surface anatomy also reveals prominent venous vascularity in the lower leg and skin tension changes between extension and flexion. These findings are clinically characteristic of habitual patellar dislocation, often associated with component malalignment or soft tissue imbalance following knee replacement surgery.

This clinical photograph captures an intraoperative view of an open orthopedic surgical procedure on the knee joint, specifically demonstrating a lateral soft tissue release for the treatment of habitual patellar dislocation. The surgical field shows a deep midline incision with significant exposure of the underlying musculoskeletal structures. The patella and patellar tendon are visible, surrounded by dissected soft tissues including vastus muscle fibers and connective fascia. Evidence of active surgical manipulation is present through the visible bone surfaces and blood-tinged tissues. A gloved hand is shown in the foreground holding an electrosurgical unit (bovie) to maintain hemostasis or perform further dissection. Additional metallic surgical instruments and a blue suction or monitoring tube are positioned within the operative site. This image serves as a high-level educational example of the complex soft tissue releases required to achieve anatomical patellar reduction in adolescent patients.