The Role of 3D Printing in the Positioning of the Glenoidal Component in Total Shoulder Arthroplasty. An Experimental Study

The total shoulder arthroplasty is the surgical treatment when the non-surgical treatment fails. The key point of this procedure is the correct implantation of the glenoidal component to avoid the loosening and to promote long term survival of the implant. Despite of the use of medical images resources in pre-operative planning, this procedure continues to be challenging due to difficulties in the correct spatial positioning of the components. The 3D print brought the possibility to reproduce the anatomy of the patient being helpful in the pre-operative planning, due to the real tridimensional characteristics. The objective of this study is to evaluate the positioning of the glenoidal component in total shoulder arthroplasty comparing the use of TC scans and anatomic 3D print models, from patients with shoulder osteoarthritis, in the pre-implantation planning. From nine consecutive patients submitted to a total shoulder arthroplasty were generated 54 3D print scapula models, used for implant polyethylene glenoid component, hiding the anatomic parameters like in a real surgery, done by three intervenors in a randomized way, using in the pre-operative planning the correspondent CT scans or the anatomic 3D printing scapula. The angular positioning in anteroposterior view and axillary view related to the scapula body, was evaluated with X-Ray, and measured by tree independent evaluators. It was no significant difference when comparing the measures of angulation of the implantation of glenoidal components in osteoarthritis scapula models, when comparing the use of the TC scans or the 3D print scapula models in pre-implantation planning, with exception founded in one intervenor, in anteroposterior view, in favor of 3D printing model. When comparing the use of 3D printed scapula and TC scans for planning the implantation of glenoidal component in total shoulder arthroplasty, both methods proved to be equivalent.