Osteotomy wedge angle - Aiming to achieve perfection with new device: Pre-clinical stage.

INTRODUCTION

The surgical execution of osteotomy requires precision in measuring the wedge angle. The pre-operative planning methods are plenty and so are few devices for high tibial osteotomy. But struggle happens for those bony areas other than proximal tibia where alignment correction is needed. The new device is proposed to address this surgical problem. The ease of measuring angle for bony wedge angle, in any bone, independent of its width and in any plane, is the question being solved with the proposed devices.

METHODS

Two jig instruments have been shown in the study. First one the curved with direct angle measuring marking in degrees on the body. K wire is accepted through the tower exactly showing the desired angle. The second jig instrument is flat design with marking in millimeters. This device works on trigonometric principle of sum of angles of any triangle is equal to 180°. The jig can be removed leaving the k wires in place to complete the final osteotomy once confirmed.

RESULTS

It's a pre-clinical stage study. The saw bone models show encouraging measurements and perfect execution of angle at the osteotomy site.

DISCUSSION

HTO has been researched a lot with many options of surgical devices. The criticism of using known devices is the variable accuracy, especially for the smaller width of tibial metaphysis. One major limitation of these available instruments is they can be used only for proximal tibial metaphysis. For any other surgical sites like distal femur, distal tibia, distal humerus or tibial slope correction neither these HTO jigs will work nor there is any available universal instrument as such. The common misconception of one degree equal to 1 mm does not stand true at all bony sites. Hence there was a need to solve this problem with universal jig. I have designed two new devices which are currently at pre-clinical stage. The curve device has limitations which get corrected in straight device. The philosophy changes from one direct measurement with two tips of wires forming the angle in a curved device to indirect measurement by simple trigonometric calculation in a straight device. The proposed new device would work in any bone, for any trapezoidal wedge shape osteotomy using simple user-friendly k wires.