Surgical Navigation: Tibia plateau fracture with knee osteoarthritis

Quick case summary

A while ago a troubling case presented itself: a patient with proximal tibia fracture, with basically little to no cartilage remaining anywhere. The tibia plateau was damaged (quite an understatement at least from my experience), and the pieces broken off started to absolve in the surrounding tissue. The task, as usual, was to plan the total knee arthroplasty with proper alignment, and create patient-specific surgical guides.

What made the situation even more difficult was that apparently the patient could not be scanned according to the protocol in use, due to the limitations caused by the joint deformity. However, the unusual placement of the lower limb - not even close to being straight - on the CT scanning table did not affect the outcome. Sure, the usual viewing angles in the software didn’t make much sense anymore, but the orientation was consistent throughout. The pre-operational planner was prepared for such a case: the assistance of local inertia axes for every individual bone segment really made the difference.

The images show:

• the pre- and post-op X-rays,

• the precision of the cuts (blue: planned versus green: actual) after the mesh-to-mesh registration of the pre- and post-op 3-D femoral and tibial model pairs were accomplished (possibly more on this process later),

• as well as the mesh models of the inserted prosthesis components (colored grey on both images).

The pre-op proximal tibia is displayed as semi-transparent for a better view of the ‘underlying’ tibial prosthesis component. Regarding the accuracy of the resections, usually any value between 0°-3° is considered to be of good quality.
(Apparently “3” seems to be the magic number to hit even when it comes to relative distance in such cases, measured in millimeters of course).