Implantable limb lengthening nail driven by a shape memory alloy

摘要

An implantable intramedullary bone lengthening device for correction of limb length deficiencies without a need for transcutaneous connections. The implantable intramedullary bone lengthening nail has an implantable housing, an adjustment mechanism attached to the telescoping cylinder housing, and a drive assembly attached to the housing and the adjustment mechanism for transmitting an expansion force to the adjustment mechanism. The implantable housing may be sealed, encapsulating the unit. The intramedullary bone lengthening nail is inserted into the intramedullary cavity of a bone, which may have been enlarged by reaming. The implantable housing of the intramedullary nail is formed from two telescoping cylinders and is affixed at either end to the bone using pins. The adjustment mechanism is attached to both cylinders of the housing and includes a mechanism for expanding the nail and a ratcheting mechanism for regulating the expansion. The drive assembly includes a shape memory alloy to provide an expansion force. The drive mechanism transmits the expansion force in response to an external signal to the adjustment mechanism.