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Abstract

An isometer for determining isometric graft tunnel placement for lateral side surgical augmentation or reconstruction for anterolateral or posterior lateral rotary knee instability. This graft tunnel placement isometry assessment and measurement device is designed to be used with a graft and an extra-articular technique that restores rotatory, lateral, and anterior/posterior knee stability when used by itself or in combination with intra-articular ACL/PCL reconstruction. The isometer includes an elongated body with a slider rod that slides horizontally within the body and a cannulated fixed stylus attached transversely to the first end of the elongated body. Within that cannulated fixed stylus is a guide pin that slides freely but that can also be fixed using a fixed-stylus set screw. Similarly, a cannulated movable stylus is attached transversely to the first end of the slider rod, and within that cannulated movable stylus is a guide pin that slides freely but that can also be fixed using a movable-stylus set screw. There is a pointer encircling the slider rod that slides with the slider rod, but whose position along the slider rod can also be adjusted manually. The slider rod may also have a rotatable member that allows each end of the slider rod to rotate relative to the other end. The rotatable member obviates slider rod impingement during operation. To determine rotary knee isometry during knee reconstructive surgery, the guide pins are positioned over previously identified lateral reconstruction tunnel sites. The guide pins are then driven into the bone tunnel sites and the knee put through a full range of motion by flexing and extending the knee while the isometer position is maintained and the pointer movement is monitored. If movement of the pointer is unacceptably large, the guide pins are re-set, re-positioned and re-driven into different pre-identified lateral reconstruction tunnel sites, and pointer movement during full range motion is again monitored until movement is acceptably small.

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First Claim