The present invention provides a novel concept of modular instrument for tibial resection in knee replacement surgery. It provides accurate alignment thereby improving the accuracy of the surgery and makes the surgery easier to perform.The present invention has two modules: Extramedullary (EM), which works on extramedullary referencing principle, and intramedullary (IM), which works on intramedullary referencing principle.These two different modules (intramedullary and extramedullary) are combined in a single modular cutting instrument.The integration allows use of both the referencing principles and reduces the limitations that occur when the principles are used in separate instruments. The present invention provides and ensures more accurate use of both extramedullary and intramedullary referencing principle