Both-column fractures, characterised by lines developing on multiple planes, are the most complex of all acetabular fractures [9,10,11,12,13]. The detachment of the entire weight-bearing articular surface from the sacroiliac joint is truly pathognomonic of this injury [9,10,11]. This injury is often caused by lateral direct impact, which is accompanied by central dislocation of the femoral head. In the treatment of such fracture, the specific injury of the acetabular wall, especially the posterior wall, must be defined, as it can affect the surgical approach and prognosis. In addition, we should also consider secondary congruence that might have impact on the indication for surgery. This state would allow hip joint contact stresses to be evenly distributed throughout the articular surfaces. The long-term results after nonoperative management of both-column fractures is better than other fracture patterns that affect the weight-bearing surface of the acetabulum [14,15,16].
There are various classification schemes for acetabular fractures [14, 17,18,19,20,21,22], but the Judet-Letournel classification system remains the most widely accepted [14, 17]. The both-column fracture maps can also be helpful to better understand the existing classification system. The OTA/AO classification system [18] divides acetabular fractures into three categories (group A, group B and group C), each of which includes three subcategories (1, 2, and 3). Pierannunzii et al. [23] classified both-column fractures into two subcategories (type I and II) based on the fracture line morphology (T- or Y-sharped). In our study, the both-column fractures of fracture line A and C were consistent with C2 and type I, those of fracture line B and C were consistent with C1 and type II, and those of the posterior column fractures involving the sacroiliac joints were consistent with C3. In addition, the fracture maps in this study revealed common fracture patterns in the anterior and posterior columns of both-column. The incidence of low anterior column fracture was slightly higher than that of high anterior column fracture.
The choice of surgical approach depends on a variety of factors that include the type of fracture, the direction of fracture displacement, whether accompanied by posterior wall fracture, the conditions of soft tissue and surgeon’s individual preference. The Ilioinguinal approach has been found to be effective in the management of both-column fractures. The specific procedure is that the anterior column fracture is directly reduced through this approach and the posterior column fracture is indirectly reduced, but the premise is that the posterior column fracture is only an isolated large fragment [2, 15]. A single conventional anterior approach is not a good way to deal with posterior wall fractures when double column fractures are combined with posterior wall fractures. Surgical indications for fixation of posterior wall fractures include hip instability, marginal impaction of the articular surface, and intra-articular fragments [24]. Because of the involvement of the posterior wall, some authors recommend the simultaneous addition of Kocher-Langenbeck approach or two-staged procedures for both-column fractures [25, 26]. However, extensile approaches have been reported to be associated with higher rates of complications [25,26,27,28]. To optimize treatment and reduce complications, it has been necessary to use limited exposures and understand the common fracture patterns in both-column fractures. Our understanding is that low anterior column fracture (fracture line A in the study) can be reduced and fixed through Stoppa approach, while high anterior column fracture (fracture line B in the study) can be treated through Ilioinguinal approach or combined Stoppa and iliac fossa approach (Fig. 5).
In this study, we identified a Y-shape region with a high incidence of comminution composed of three major fracture lines; these included (1) the fracture line from the point near the anterior superior spine towards the ischial spine, (2) that from the iliac crest to the acetabular roof, and (3) that traversed posterior wall. Furthermore, in the cases of both-column fractures we studied, posterior wall fractures tended to be concomitant. The most common pattern was a fracture line traversing posterior wall.
These results can facilitate the identification of critical locations at which to access displaced fractures. Surgeons can apply our study results to guide the placement of implants for optimal screw purchase and internal fixation. Additionally, we can also combine anatomical parameters of the pelvis with the main fracture lines to design a novel internal fixation device, which is the focus of further research in the future.
Our study has several limitations. First, it was a retrospective review of prospectively gathered data for a small number of patients. Second, our analysis did not take potential variability in anatomy and injury mechanism into account. Third, some hemipelvis images did not match the hemipelvis model perfectly. Finally, fracture lines drawn on the hemipelvis model could slightly differ from true fracture morphology.