Delayed total hip arthroplasty after failed treatment of acetabular fractures: an 8- to 17-year follow-up study

Acetabular fractures are serious injuries which can lead to progressive impairment of hip function [1]. Anatomic reduction with rigid internal fixation of the acetabulum has been shown to restore hip function and prevent long-term complications. Unfortunately, many patients with fractures of the acetabulum still suffer posttraumatic arthritis or femoral head necrosis regardless of whether operative or non-operative intervention was chosen as the initial treatment. These irreparable complications may occur as a result of residual articular incongruity, early articular cartilage damage, inaccurate placement of implant fixation, and disruption of femoral head blood provision. Even when near-anatomic reductions are achieved, the reported incidence of posttraumatic arthritis has been varied between 27 and 37% [2], with the incidence of subsequent total hip arthroplasty (THA) ranging from 8 to 23% [2‐4].

When posttraumatic arthritis and femoral head necrosis occur, THA is a rational salvage procedure. Retained internal fixation implants, scar tissue, and residual acetabulum bone defects cause subsequent THAs to be more complex than routine THA [5, 6]. Moreover, the results of these THAs presented to be inferior to THA performed after primary osteoarthritis [7‐9], attributable to the extent of loss of bone stock and abnormal anatomy after trauma [9‐11]. Therefore, some authors recommended that initial open reduction internal fixation (ORIF) is essential to restore the bony anatomy for subsequent THA, decreasing its complexity and improving component survival [12‐14]. Conversely, others have postulated that initial ORIF increases the rate of infection, blood loss, and surgery time [6, 15]. Furthermore, there is no explicit evidence that ORIF improves the success rate of subsequent THA [16].

Additionally, patients with acetabular fractures are generally young and have posttraumatic osteoarthritis that results from a high activity level. A series reports high failure rates of subsequent THA, which have been attributed to younger age and increased activity [9, 11]. Therefore, in those patients, alternative bearing surfaces should reduce polyethylene wear and osteolysis that have been present in previous studies using traditional metal-on-polyethylene (MOP). Recently, modern ceramic-on-ceramic (COC) THA has demonstrated decreased risk of wear-induced osteolysis over MOP and then improved the long-term outcomes of THA [17, 18].

Therefore, the primary aim of the present study was to evaluate the influence of the mode of treatment of fracture, conservative treatment or ORIF, on the clinical outcomes of salvage THA. The secondary aim was to evaluate the long-term results associated with modern COC THA after failed acetabular fractures.

All patients who underwent THA for posttraumatic osteoarthritis or femoral head necrosis due to acetabular fractures during the period from January 1997 to January 2008 were eligible for inclusion in this study. Exclusion criteria were incomplete radiographic or clinical date and without adequate follow-up. Two patients (2 hips) had died of causes unrelated to surgery. Five patients (5 hips) were lost to follow-up. Thus, 33 remaining patients (33 hips) were available for review. Patient demographics and characteristics of the fractures are summarized in Table 1. This study was approved by our institutional review board.

When posttraumatic osteoarthritis develops secondary to acetabular fracture, THA is considered a reliable procedure to relieve pain and restore function [8, 26, 27]. Failed acetabular fractures after non-operative treatment often have bone defects, suffer non-union, or have residual pelvic deformity from malunion [11]. Similarly, following initial ORIF treatment, THA procedures not only faced the same difficulty as non-operatively treated fractures, but they also suffered problems related to previous surgery such as proliferative scar tissue, heterotopic bone formation, or obstructive hardware [6, 8, 9, 28]. In our study, we observed that the surgery duration and blood loss were greater in the ORIF group than in the non-ORIF group. However, no significant difference in average HHS was observed at the final follow-up between the two groups (ORIF group 89 vs non-ORIF 87.9, p = 0.57). In brief, performing a salvage THA following acetabular fracture is a challenging procedure. ORIF prior to THA resulted in more complex surgery which did not improve the final clinical outcome.

Acetabular bone defects and abnormal anatomy are contributing factors to the inferior THA outcomes experienced in the setting of previous acetabular fractures [7, 27]. Weber et al. [8] also demonstrated that large deficiencies in acetabular bone were associated with a poorer rate of long-term outcome after delayed THA. To restore bone stock and minimize acetabular deformity, various reconstruction techniques have been described to treat this issue effectively. IBG, a widely accepted technique for acetabular reconstruction after bone stock loss in revision THA, represents one option. Postoperative longevity of the acetabular component achieved from this technically demanding procedure is well documented in previous literature [29]. Based on this favorable experience, we reconstructed the acetabulum using the IBG technique with a cementless hemispherical cup in this study, obtaining sufficient host bone coverage and stability fixation (Fig. 2). Additionally, our results of THA in patients who were treated with ORIF for acetabular fractures demonstrated that ORIF did not reduce the incidence of bone defects compared with non-ORIF (6/21 vs 7/12, p = 0.09). Furthermore, the incidence of anatomical restoration was 58.3% (7/12) in the non-ORIF group and 42.9% (9/21) in the ORIF group (p = 0.12). It was shown that anatomical restoration was not associated with fracture treatment (r = 0.248, p = 0.163). What is more, there was also no clear evidence that ORIF could improve the long-term outcomes of the subsequent THA. Ranawat et al. [16] also hypothesized that initial ORIF was not an essential procedure before THA and that anatomical restoration was not related to fracture treatment. Moreover, there was an increased risk of infection, peri-articular ossification, and scar tissue, and the presence of retained hardware increased the duration of surgery and blood loss [6, 28].

Ranawat et al. [16] reported that acetabular component survival rate was 97% with aseptic loosening and 79% with revision for any reason. Bellabarba et al. [13] also described a 10-year survival rate of 97% after uncemented acetabular reconstruction. In our study, we demonstrated a cementless acetabular component survival rate of 100% with loosening and 88.9% with revision for any reason, because of two “sandwich” ceramic liner fractures due to part design defects [30, 31]. After performing revision surgery, those two hips had well-fixed implants with no radiolucencies and had good clinical results in the follow-up study. Furthermore, acetabular component survival in both groups was similar regarding any reason at a mean follow-up of 11.5 years (Fig. 3). In brief, complex reconstruction in the non-ORIF group did not affect component survival and none of the hips were revised because of aseptic loosening.

Wear debris from conventional MOP can cause extensive osteolysis, threatening the long-term survival of cementless cups, especially in young patients [32]. Berry and Halasy [33] reported that 67% of revisions were associated with polyethylene wear and osteolysis. Roth et al. [26] reported that survivorship of the acetabular component declined from 87% at 10 years to 57% at 20 years for polyethylene wear or loosening. Similarly, our results revealed that 8 of 12 patients who underwent THA with conventional MOP had partial radiolucent lines at the bone-implant interface (Fig. 4). The most likely explanation for periprosthetic osteolysis in these patients is low patient age (average 45 years) combined with high activity level. Conversely, we did not observe osteolysis in any patient in the ceramic-on-ceramic group. Our previous study demonstrated that THAs using COC suffer significantly reduced wear and demonstrated improved component longevity [17]. On the basis of the data presented, therefore, one could speculate that optimization of long-term results with COC surfaces has the potential to solve the most common problems that result in revision surgery being required in these patients (aseptic loosening and osteolysis).

Our study may have some limitations. First, this was a retrospective study and not a prospective randomized study, which increased the possibility of selection bias. Secondly, the number of patients in the study was relatively small, and further studies involving more participants are anticipated. Finally, the acetabular components used in this study were not uniform and thus may compromise the robustness of the results.

In conclusion, Delayed THA with previous acetabular fractures is a challenging procedure. Our study found the initial fracture treatment does not influence the functional results and component survival of subsequent THA at long-term follow-up. Although acetabular osteolysis was observed in our patients, we believe that cementless THA with modern ceramic bearing surfaces will eliminate periprosthetic osteolysis and further improve long-term results.