A 48-year-old man presented to his primary physician with pain localized to the medial region of the left knee of 6 months' duration. The physical examination was normal. His medical history was unremarkable. He was treated empirically with nonsteroidal antiinflammatory medications and physiotherapy without relief. After 3 months of continuing pain, he was referred to an orthopaedic surgeon who ordered an MRI scan which was interpreted as normal. The patient was maintained on symptomatic treatment for several more months with no substantial improvement. The patient continued to endure the pain and utilise symptomatic treatment for the following couple of years. Three years after initial presentation, he obtained a second orthopaedic opinion and had another MRI scan. The examination was again normal and the MRI interpreted as normal. The patient was maintained on symptomatic treatment with no improvement. Throughout he had no constitutional symptoms.The patient presented to our clinic 5 years after his pain first developed. Physical examination of the knee was normal. There was no instability, no joint line tenderness, no crepitation, and full range of motion. He had considerable atrophy and weakness of the quadriceps muscle. Physical examination of the hip and the spine were normal. There was an area of exquisite pinpoint tenderness medially above the joint line, overlying the adductor canal (Fig.