A modular implant system comprising: an intramedullary implant having a shaft a first modular implant part having first and second opposing surfaces and an inner core section; a second modular implant part having first and second opposing surfaces and an inner core section, wherein the first and second modular implant parts are engageable and, when engaged, the inner core sections of the first and second modular implant parts collectively define an inner core of the modular implant system that has a shape that corresponds to a shape of a portion of the intramedullary implant; a third modular implant part having first and second opposing surfaces and an inner core section; and a fourth modular implant part having first and second opposing surfaces and an inner core section, wherein the third and fourth modular implant parts are engageable and, when engaged, the inner core sections of the third and fourth modular implant parts collectively define an inner core of the modular implant system that has a shape that corresponds to the shape of the portion of the intramedullary implant, and wherein the second surfaces of the third and fourth modular implant parts are engageable with the second surfaces of the first and second modular implant parts, such that the third and fourth implant parts are arrangeable on the first and second modular implant parts in a stacked configuration wherein the first modular implant part includes a hole and the third modular implant part includes a first locking hole, and wherein when the first modular implant part is stacked on the third modular implant part, the hole and the first locking hole of the third modular implant part are aligned; wherein the system further comprises a fixation member insertable through the hole and into the first locking hole of the third modular implant part, the fixation member being configured to engage the first locking hole of the third modular implant part and lockingly join the first modular implant part to the third modular implant part and wherein the modular implant parts of the system are rotatable about the shaft of the intramedullary implant. an intramedullary implant having a shaft a first modular implant part having first and second opposing surfaces and an inner core section; a second modular implant part having first and second opposing surfaces and an inner core section, wherein the first and second modular implant parts are engageable and, when engaged, the inner core sections of the first and second modular implant parts collectively define an inner core of the modular implant system that has a shape that corresponds to a shape of a portion of the intramedullary implant; a third modular implant part having first and second opposing surfaces and an inner core section; and a fourth modular implant part having first and second opposing surfaces and an inner core section, wherein the third and fourth modular implant parts are engageable and, when engaged, the inner core sections of the third and fourth modular implant parts collectively define an inner core of the modular implant system that has a shape that corresponds to the shape of the portion of the intramedullary implant, and wherein the second surfaces of the third and fourth modular implant parts are engageable with the second surfaces of the first and second modular implant parts, such that the third and fourth implant parts are arrangeable on the first and second modular implant parts in a stacked configuration wherein the first modular implant part includes a hole and the third modular implant part includes a first locking hole, and wherein when the first modular implant part is stacked on the third modular implant part, the hole and the first locking hole of the third modular implant part are aligned; wherein the system further comprises a fixation member insertable through the hole and into the first locking hole of the third modular implant part, the fixation member being configured to engage the first locking hole of the third modular implant part and lockingly join the first modular implant part to the third modular implant part and wherein the modular implant parts of the system are rotatable about the shaft of the intramedullary implant.