AO Technical Commission Approved

Expert Modular Aiming Device (ModAD)

The current standard technique for distal locking is the freehand technique. The surgeon needs to be experienced in order to hit the hole correctly and he/she is exposed to a lot of radiation. Furthermore, there is a lack of C-arms in certain regions.

The Expert Modular Aiming Device (ModAD) is a purely mechanical aiming support which enables image-intensifier-free locking for the distal interlocking of the expert tibial nail (ETN), expert lateral femoral nail (LFN), expert retrograde/antegrade femoral nail (R/AFN), and the expert humeral nail. The ModAD cannot be used for TFN, PFN, or PFNA.

With a rigid aiming device, the nail-tip locking of an intramedullary nail cannot be performed with the required precision due to the deformation of the nail during insertion. An analysis of this deformation shows a spread of the UTN tip position of more than 19 mm in the sagittal plane and 14 mm in the frontal plane. The torsion of the titanium nail is insignificant and can be ignored.

Based on the above mentioned issues, an aiming device for nail-tip locking was developed, which can correct nail deformation in the sagittal and frontal planes. The reference point for the adjustment is the nail surface at the distal end of the nail. Aiming arm length as well as special spacers are intraoperatively calibrated to the chosen nail prior to insertion of the latter.

After nail insertion, the position of the locking holes can be determined by establishing contact of a spacer tip with the nail surface. Drilling and screw insertion can then be performed as in proximal locking, using sleeve systems through the aiming arm.

Different aiming arms, aiming arm extensions, L-spacers, etc, exist for the different nail geometries and locking options of the different expert nail systems.

Hazards and labeling

Due to varying countries’ legal and regulatory approval requirements, consult the appropriate local product labeling for approved intended use of the products described on this website. All devices on this website are approved by the AO Technical Commission. For logistical reasons, these devices may not be available in all countries worldwide at the date of publication. 

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