We report a rare case of an intracortical chondroma in the region of the medial femoral condyle of the femur extending into the femoral sulcus and the patellofemoral joint.A sixteen year old Asian boy presented with repeated episodes of right sided anterior knee pain and giving way over a three year period. The patient had been treated previously for multiple bony swellings at another hospital and a diagnosis of multiple enchondromatosis had been made. Examination revealed that the patellofemoral compression test was positive with fullness over the medial eminence of the femur in the region of the trochlear groove.Pre-operative X-rays and MRI scan showed the presence of an intracortical lesion over the medial femoral condyle extending into the femoral sulcus. The lesion demonstrated intermediate signal intensity on T1 and high intensity on T2 weighted images with variable low signal intensity foci due to the presence of a calcified matrix. The patient underwent arthroscopic examination. An intra-articular lesion (2cmx 3cm.) was identified and excised through a mini-arthrotomy. The lesion was entirely intra-articular arising from the medial femoral condyle proximal to the femoral sulcus, extending partially into the supra-patellar pouch. Histopathological examination confirmed the presence of a low grade cartilaginous neoplasm best diagnosed as an atypical chondroma. At a two year follow up appointment the patient was found to be asymptomatic with no evidence of radiological recurrence.

Although there have been several reports of periosteal chondromas developing around the knee the majority deal with soft tissue chondromas in para-articular locations or intra-cortical tumours in extra-articular regions. Our tumour is unique due to its intra-articular and intracortical location. A detailed review of the literature of this rare tumour is presented with a pictorial presentation of the case including arthroscopic radiological and histopathological findings.