Acetabular fractures are frequently the result of high-energy injuries [
1,
2]. In an ageing but active population, the incidence of acetabular fractures in elderly patients due to minor trauma is increasing [
3‐
6]. Most acetabular fractures are classified using the Judet and Letournel classification system [
7]. In most cases, treatment of acetabular fractures requires an open surgical fixation of displaced fragments, for which several different approaches and techniques have been described [
7‐
11]. A common long-term complication is osteoarthritis, which occurs in up to 20% of patients with displaced acetabular fractures. An important factor influencing the risk of hip osteoarthritis and functional outcome is post-operative joint congruity. This is of particular importance in fractures that involve the weight-bearing dome of the acetabulum [
1,
2,
12]. A post-operative assessment of fracture reductions is performed using objective radiographic markers of displacement. The criteria by Matta et al. [
13], which focus on any residual displacement of columns, walls and the superior dome, are often used for this purpose [
12,
13]. According to these criteria, a post-operative reduction is graded as anatomical (≤ 1 mm of displacement), imperfect (2 to 3 mm of displacement) or poor (> 3 mm displacement). These objective measures of anatomical reduction and stable fixation of acetabular fractures serve as predictors for joint functional outcome, particularly in the long term [
13‐
16]. Originally, post-operative assessments of fracture reduction were performed using plain radiographs. However, computed tomography (CT) scans provide more accurate information on intra-articular (bone) fragments, residual articular steps and gaps at the joint surface, as well as the severity of marginal impaction. Furthermore, the acetabulum can be viewed from different angles, which provides additional details on the accuracy of the fracture reduction [
17,
18]. Despite these advantages, the process of understanding fracture patterns and assessments of fracture reductions on two-dimensional (2D) CT-generated images remains difficult. The objectivity and reliability of fracture assessments and classifications using 2D CT images have been questioned, and certain radiographic markers, such as the teardrop landmark, are challenging to identify accurately [
19‐
21]. Consequently, it is difficult to form evidence-based recommendations based on these radiographic markers, as the (long-term) outcomes of the objectified residual articular incongruity have not been clearly demonstrated [
21]. A recent study described limited inter-observer reliability for CT scans in the assessment of post-operative acetabular fractures. A complicating factor herein is the lack of a specific standardised measurement technique for assessing post-operative acetabular fractures using CT scans [
18,
21]. The addition of three-dimensional (3D) reconstructions has gained popularity in the identification of fracture patterns and as a training tool [
22]. It was found that 3D CT reconstructions are easier to interpret than axial CT images [
22]. Furthermore, reconstructed 3D models, once they are validated, could also be used as a less complicated, standardised and more reliable method of post-operative acetabular fracture reduction and joint congruity assessment. Thus, it is hypothesised that the contralateral side could be used as a mirrored template for the anatomical configuration of the affected joint. If this method proves to be valid, it could be used as an objective fracture reduction assessment tool. This technique was reported to produce acceptable accuracy and repeatability for other modalities, but not for 3D models [
23,
24]. Therefore, the objective of this study is to investigate whether the right and left acetabula, as reconstructed 3D models, are mirrored duplicates that can be used as a reference model for the contralateral side.