Medial buttressing of the quadrilateral surface in acetabular and periprosthetic acetabular fractures
Authors: Rommens Pol Maria , Herteleer Michiel , Handrich Kristin , Boudissa Mehdi , Wagner Daniel , Hopf Johannes Christof 
Published: December 2020

Background
In geriatric acetabular fractures, the quadrilateral plate is often involved in the fracture pattern and medially displaced. Open reduction and internal fixation (ORIF) includes reduction of the quadrilateral plate and securing its position. In this study, the concept of medial buttressing in acute and periprosthetic acetabular fractures is evaluated.

Materials and methods
Patients, who sustained an acetabular fracture between 2012 and 2018, in whom ORIF with a specific implant for medial buttressing was performed, were included in the study. Patients were divided in two groups; acute acetabular fractures (group 1) and periprosthetic acetabular fractures (group 2). Demographics, type of fracture, surgical approach, type of implant for medial buttressing, comorbidities, general and surgical in-hospital complications and length of hospital stay were recorded retrospectively. The following data were collected from the surviving patients by telephone interview: EQ-5D-5L, SF-8 physical and SF-8 mental before trauma and at follow-up, UCLA activity scale, Parker Mobility Score and Numeric Rating Scale.

Results
Forty-six patients were included in this study, 30 males (65.2%) and 16 females (34.8%). Forty patients were included group 1 and six patients in group 2. The median age of patients of group 1 was 78 years. Among them, 82.5% presented with comorbidities. Their median length of in-hospital stay was 20.5 days. 57.5% of patients suffered from in-hospital complications. The concept of medial buttressing was successful in all but one patient. ORIF together with primary total hip arthroplasty (THA) was carried out as a single stage procedure in 3 patients. Secondary THA was performed in 5 additional patients (5/37 = 13.5%) within the observation period. Among surviving patients, 79.2% were evaluated after 3 years of follow-up. Quality of life, activity level and mobility dropped importantly and were lower than the values of a German reference population. SF-8 mental did not change. The median age of patients of group 2 was 79.5 years, all of them presented with one or several comorbidities. The median length of in-hospital stay was 18.5 days. 50% of patients suffered from in-hospital complications. The concept of medial buttressing was successful in all patients. 5 of 6 patients (83.3%) could be evaluated after a median of 136 weeks. In none of these patients, secondary surgery was necessary. Quality of life, activity level and mobility importantly dropped as well in this group. SF-8 mental remained unchanged.

Conclusion
In geriatric acetabular fractures with involvement and medial displacement of the quadrilateral plate, medial buttressing as part of ORIF proved to be reliable. Only 13.5% of patients of group 1 needed a secondary THA within 3 years of follow-up, which is lower than in comparable studies. Despite successful surgery, quality of life, activity level and mobility dropped importantly in all patients. The loss of independence did however not influence SF-8 mental values.