May 1, 2020 – authored by Robert D. Santrock, MD, FAAOS | WVU University – Today, recognition of hallux valgus as a 3D deformity has motivated the development of a third generation of the Lapidus procedure: the anatomic triplane first TMT arthrodesis. The technique incorporates the giant strides taken by Drs. Lapidus, Sangeorzan, and Hansen and adds the following: correction of the frontal plane rotation (triplanar correction), precision instrumentation for reproducibility, and multiplanar fixation. In that multiplanar fixation has been shown by the AO Institute to be extremely stable, the fixation change attempts to expedite weight-bearing. Because that portion of the foot experiences multiple vectors of force when weight-bearing, multiplanar control is needed. In a study of rapid weight-bearing after anatomic triplane first TMT arthrodesis using multiplanar fixation (Lapiplasty® 3D Bunion Correction™, Treace Medical Concepts, Inc.®, Ponte Vedra Beach, Fla.), at 13 months of follow-up, we showed a maintenance of correction of nearly 97 percent and a nonunion rate of less than 2 percent.1,2
A modern, preoperative radiographic evaluation approach should include an axial sesamoid view, which allows for evaluation of frontal plane rotation. Intraoperatively, the surgeon needs to be mindful of the primary goal of this 3D approach—concentrate on getting the metatarsal-sesamoid complex into the proper biomechanical position. Also, it is important to be aware of the effects of weight-bearing. This joint arthrodesis sits in a peculiar location that sees multiple different vectors of force when weight-bearing. If rapid weight-bearing2 is desired, the fixation construct must be compatible to see those varying forces; otherwise, limited weight-bearing is best. Finally, each case demands a look at intercuneiform instability. That is not an uncommon finding and should be addressed if an intraoperative splay test points to that pathology.
Modern understanding of the 3D aspects of hallux valgus deformity and its pathological contributions from the abnormal TMT joint may “revolutionize” patients’ and surgeons’ options for sustained corrections and cosmetically pleasing results.
Reference Link: https://www.aaos.org/aaosnow/2020/may/clinical/clinical04/