Rare case of postero medial reconstruction of knee for non traumatic instability

Postero medial corner of knee has been studied in detail recently and understanding of its role in knee stability has increased. Anatomical reconstruction of the postero medial corner has been undertaken more frequently for traumatic instabilities. A case of non traumatic instability of a knee is rarely encountered. Our case had rotatory instability of postero medial corner of left knee without any traumatic history or features suggestive of generalised ligamentous laxity. In our case the structures of the postero medial corner namely the posterior oblique ligament, semimembranosus and the capsule were intact but found lax. The osteochondroma from the proximal tibia was resected followed by advancement of the posterior oblique ligament more distally and double breasting of the postero medial capsule. The patient had excellent result with no residual instability.