Prebending of osteosynthesis plate using 3D printed models to treat symptomatic os acromiale and acromial fracture

Abstract

Background: A symptomatic os acromiale can lead to impingement syndrome and rotator cuff tendinopathy. An acromion fracture is often part of a more complex scapular trauma that needs stabilisation.

Methods: We developed a new technique using a three-dimensional (3D) model and a distal clavicle reconstruction plate to treat os acromiale and acromion fractures. Our hypothesis was that such an approach would be a useful addition to the existing techniques. First, a 3D model of the acromion was printed, then an osteosynthesis plate was pre-bent to fit the exact shape and curve of the acromion. We tested this technique and present reports on five patients, three with os acromiales and two with acromial fractures. We followed these patients during their rehabilitation and evaluated them using the Constant-Murley and the Disabilities of the Arm, Shoulder and Hand scores.

Results: In every case the fracture or non-union healed. If the surgery was performed before additional damage (such as an impingement syndrome) occurred, we saw that the patient's pain completely disappeared. This new technique also has other advantages because the surgeon can prepare the entire operation in advance, which reduces the duration of surgery. Another advantage of using a 3D model is that it can also be used to inform the patient and the surgical team about the planned operation.

Conclusion: This new technique using a preoperative patient-customized plate is a good alternative for use in open reduction and internal fixation, particularly if the patient has no other conditions.

Keywords: 3D printing; Acromial fracture; Case report; Os acromiale; Osteosynthesis plate.

Fig. 1

Process of 3D printing. A 3D CT scan (DICOM file) was converted into a file the printer could recognise using InVesalius freeware. Rhinoceros 5 and Netfabb Pro were used to segment the desired area of interest, after which Meshmixer was used to extract a surface from this area (meshing) and for further processing of the image (correction, solid assembly and support). A 3D print was made using the MakerBot Replicator 2X Experimental printer

Fig. 2

Bending the osteosynthesis plate based on the 3D print. A correction was made to lift the anterior acromion and to prevent further impingement on the rotator cuff

Fig. 3

Course of the surgery. The patient was placed in the beach-chair position without a tourniquet (left). A longitudinal incision was made along the scapular spine to visualise the entire os acromiale or acromial fracture (middle). The osteosynthesis plate was fixed anteriorly with angle-stable screws and posteriorly with angle-stable screws and at least one cortical compression screw to compress the fracture (right)