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In this scenario, the child is presenting with specific symptoms: left hip and knee pain, a limp, and limited internal rotation and abduction of the left hip. These findings are characteristic of Legg-Calve-Perthes Disease, a condition where the blood supply to the femoral head is temporarily disrupted, leading to avascular necrosis.

In Legg-Calve-Perthes Disease, the classic presentation includes hip pain that may radiate to the knee, and the child often exhibits limited range of motion, particularly in internal rotation and abduction. This limitation occurs due to the involvement of the hip joint and the developmental changes associated with the necrosis and subsequent healing processes.

The age of the child, as well as the described symptoms and examination findings, aligns perfectly with Legg-Calve-Perthes Disease, making it the most likely diagnosis in this case. Other conditions may present with hip pain and altered mobility but would typically show different physical examination findings or demographics that do not fit this child's profile as accurately. For instance, slipped capital femoral epiphysis usually presents with a different pattern of limitation, and transient synovitis often does not lead to the same degree of limitation in range of motion.