Histological and enzyme histochemical study on the injured knee meniscus in human.

The activity and distribution of 10 enzymes was determined in the ruptured knee meniscus of 23 patients, when meniscus was operatively removed. The activities of NADH and SDH indicating oxydative energy metabolism were low in the ruptured meniscus as well as in the synovium close to it. On the contrary, NADPH and LDH, indicating anaerobic energy metabolism and G-6-PDH as an indicator of pentose-phosphate shunt, showed moderate or high activity. The activities of GLDH, ATPase, AcPase, AlPase, and LAPase were low in the meniscus tissue, but moderate and sometimes high in synovial tissue and fibroblasts close to the meniscus. In the vascular walls these enzyme activities all were moderate or high indicating reparative capacity in the peripheral, vascularized part of meniscus. The age of the patients as well as the time interval between the trauma and the operation was not in relationship with enzyme activities studied.