Design of custom acetabular components: influence of the type of defects on the design

Options for treatment of massive acetabular defects are very diverse and continue to be a challenge for the surgeon. Although custom implants do not perform well over other reconstruction methods, design variability offers wide option for reliable primary fixation. There were performed 115 acetabular reconstructions with custom implants in Russian Scientific Research Institute of Traumatology and Orthopedics named after R.R. Vreden of the Ministry of Health of the Russian Federation from 2015 to 2019 years. The aim of our study was to clarify and define main types of custom implants which were used for reconstruction of extensive acetabular defects. Despite the most defects refers to such categories as 3 A , 3 B according to Paprosky and pelvic ring discontinuity, the type of custom implants was determined to a greater extent by the geometry of the defect. Custom implants were used as augmentation of posterior, anterior or superior wall in the cases when the medial wall was saved. When medial support was absent, custom implants had bridge-like fixation and antiprotrusion properties. In the most severe cases, in the absence of support and connection with the axial skeleton, custom acetabular component had iliac flange and a stem that was fixed in the posterior parts of the iliac body. The main design types of the presented constructions are represented by augments, threeflange and flanged constructions with a stem. Along with patient-specific acetabular reconstruction various design types wided primary screw fixation options, allowed us to find optimal hip rotational center position and acetabular cup orientation yet at planning stage. Custom designing of acetabular implants lets combine different fixation options of various acetabular implant types.