Clinical interpretation of cysts in the popliteal space using computerised tomography

The use of computerised tomography in the examination of the knee joint has made it possible to investigate popliteal cysts much more precisely, particularly as regards incidence, localisation, size, shape and above all their possible relationship with other pathological conditions. In 315 examinations, 60 patients (19.5%) were found to have cysts in the popliteal space of whom only 9 were unassociated with any other pathology of the knee. Fifty-five (91.6%) of these cystic dilatations were semimembranosus bursae. The two pathogenetic theories which are favoured at the moment were considered in the light of our findings, but it appears from our experimental work that both could be valid.