Knee intra-articular loose body causing a compression common peroneal nerve neuropathy with foot drop

We present a unique case of a man in his 60s with a knee intra-articular loose body causing a compression neuropathy on his common peroneal (fibular) nerve (CPN). This neuropathy caused a reduction in function of his leg's motor function causing a foot drop. Through a strong clinical interview and focused clinical examination, the neuropathy was localised, and the diagnosis was reinforced through nerve conduction studies and imaging. The intra-articular loose body was surgically excised after the careful isolation and decompression of the peroneal nerve. This resulted in a marked improvement in the patient's motor function and symptoms, allowing him to ambulate and return to normal function. To our knowledge, this is the first case report of an intra-articular loose body in the knee causing a compression CPN neuropathy with symptoms such as foot drop. We hope this case report aids in guiding management should physicians come across this issue in the future.