Background: Acetabular fractures result from violent trauma, and their incidence has been increasing in recent years. The Kocher-Langenbeck surgical approach is used for the internal fixation of displaced fractures of the posterior structures of the acetabulum. The quality of the reduction and the stability of osteosynthesis directly influence the function of the repaired acetabulum. In the surgical management of acetabulum fractures, 3D printing of a bone model is increasingly used during preoperative planning by trauma surgeons worldwide.

Questions: Is there a difference in the surgical time of the Kocher-langenbeck reduction and fixation of the posterior structures of the acetabulum between 3D printing (which allows for shaping of the reconstruction plate prior to surgery) and the conventional technique? Are there any differences in complications between the two techniques? Are there any short-term differences in the functional and radiographic scores between 3D printing and the conventional technique? Methods: 109 consecutive patients who sustained fractures of the acetabulum were screened for inclusion. 43 patient were studied. The first group (G1) consisted of 20 patients who underwent prior molding of the osteosynthesis plate on a 3D-printed model. The second group (G2 or control group) included 23 patients who underwent surgery using the conventional technique. We compared surgical time, intraoperative blood loss, the difference between pre- and postoperative hemoglobin, and the onset of early infection, paralysis of the sciatic nerve, and deep vein thrombosis.

This randomized, prospective study included 109 consecutive patients who were treated for fractures of the acetabulum between September 2016 and February 2019 at our institution. This study was approved by the ethics committee at our institution and verbal and written informed consent was obtained from all patients. The final analysis included 43 patients (33 males and 10 females) who underwent the Kocher-Langenbeck approach for the reduction and fixation of the posterior structures of the acetabulum.

The patients were divided into two groups. Group 1 (G1) consisted of 20 patients who underwent preoperative molding of the osteosynthesis plate on a 3D printed model of the pelvis. Group 2 (G2 or control group) included 23 patients who underwent surgery using the conventional technique.

All patients were examined in the outpatient department via clinical and radiographic evaluation at 3, 6, 12, and 24 weeks postoperatively, then every 6 months thereafter. A standard radiographic assessment including three views (AP, iliac oblique, and obturator oblique) and a pelvic CT scan were obtained for all patients at the last follow-up visit. The reductions were classified as one of three types: anatomical (residual displacement <1 mm), imperfect (residual displacement 1 to 3 mm), and poor (residual reduction >3 mm). Clinical outcomes were assessed using the modified Harris Hip score. Bone consolidation was obtained in all cases. Clinical and radiographic results at the last follow-up as well as the minimum follow-up duration were evaluated by one surgeon who did not participate in the surgical management of the patients.

Inclusion Criteria:

• Fractures of the posterior structures of the acetabulum
• treatment using the Kocher-Langenbeck approach.

Exclusion Criteria:

• age over than 60 years
• treatment approach other than the Kocher-Langenbeck's ( eg orthopedic method)
• open fractures of the pelvis
• fractures of the acetabulum older than 3-weeks
• polytrauma with/or multiple fractures.
• unavailability for follow-up
• insufficient clinical and radiographic data.

No: There is not a plan to make IPD available.

Clinical and radiographic results at the last follow-up were evaluated by one surgeon who did not participate in the surgical management of the patients