Use of 3D Planning and Patient-specific Guides for Proximal Humerus Corrective Osteotomy Associated With Shoulder Prosthesis Implantation in Proximal Humeral Varus Malunion.

Humeral stem prosthesis implantation in case of proximal humerus varus malunion (type 1D fracture sequelae) is often complicated by greater tuberosity fracture and by posterosuperior rotator cuff iatrogenic damage. Moreover, the varus malunited humeral head could lead to scapular impingement and reduce the range of motion. To address this problem, we introduced a new surgical procedure consisting in a proximal humerus osteotomy, planned with three-dimensional (3D) preoperative virtual surgery, and performed with patient-specific surgical guides, to correct humerus deformity before the implantation of the prosthetic humeral stem. A 3D evaluation of the deformity, based on the comparison to the healthy contralateral side or to anatomical standard values, is firstly performed. The metaphyseal osteotomy is then planned and virtually performed. To faithfully reproduce the planned correction, 3D printed surgical guides are prepared. Before the surgery, it is advisable to perform a simulation of the planned osteotomies to verify their real feasibility and to find any critical issues. Preliminary outcomes of this surgical technique are encouraging, but formal studies are warranted to validate its clinical utility and longevity of results.