Fractures of the acetabulum result from high-energy trauma and rarely are associated with a proximal femoral fracture. According to the fracture sites of the proximal femur, we divided these injuries into three groups: acetabular fractures with femoral head fractures, femoral neck fractures and intertrochanteric fractures. In this study, similar to acetabular fracture with femoral head (or neck) fracture, almost all patients were victims of high-impact trauma (e.g., a traffic accident or a fall from a tall height). In addition, 6/18 patients also had a dislocated hip joint. Some patients with acetabular fractures present with hip joint dislocations that most commonly result from high-impact trauma and damage to hip joint stability[14, 15]. This indicates that after causing fractures at two sites around the hip, the impact from the trauma still may not be fully absorbed and may cause the hip joint to be dislocated[7, 16–18]. According to the Evans classification, most intertrochanteric fractures are type 3 or type 4, which are considered unstable[19, 20]. The most common type of acetabular fracture is a posterior wall fracture, which has a weaker influence on stress distribution but a stronger influence on the stability of the hip joint[13, 21, 22].
Because they result from high-impact, intra-articular injuries, acetabular fractures with ipsilateral intertrochanteric fractures always present innate difficulties for surgeons in terms of their management[9, 11, 18, 23]. In this study, all patients received surgical treatment. However, instead of an emergency surgery, all patients received their operations several days after injury when he or she was hemodynamically stable and well prepared for surgery. During this period, patients were treated with bone traction. If the fractures were combined with a dislocated hip joint, the patient was not treated with an emergency closed reduction because the continuity of the femur was damaged, thus making closed reduction quite difficult. The reduction of the hip joint was achieved together with the surgical treatment of the fractures. For acetabular fractures, surgical treatment is not always necessary[24–27] because in some cases, fractures are considered stable without displacement, and the fracture has little influence on the weight-bearing function of the hip joint[28–30], such as a small fracture fragment (no more than 1/3 of the area of the posterior wall) without displacement on the posterior wall. If the fracture is considered unstable with displacement greater than 2 mm, surgical treatment should be performed to achieve anatomical reduction to avoid the potential incidence of posttraumatic arthritis[31–33]. However, in some situations in which the fracture is comminuted and cannot be anatomically reduced, the fracture fragments are resected to avoid the formation of intra-articular free bodies[34–36]. Reconstruction plates and screws were the most commonly used internal fixation for acetabular fractures. The treatment principle for intertrochanteric fracture combined with an acetabular fracture is similar to an isolated intertrochanteric fracture. Intertrochanteric fractures are generally considered unstable[3, 8]; thus, surgical treatment has been performed in all patients. If a patient received surgical treatment for an acetabular fracture, the intertrochanteric fracture could be treated by the same incision (or with some extension). Otherwise, the intertrochanteric fracture could be treated with a minimally invasive surgical procedure (closed reduction and internal fixation). In the past, dynamic hip screws were commonly used for intertrochanteric fracture fixation, and more recently, intramedullary nails and plates (with screws) have been commonly used. By the surgical or conservative treatment described above, both acetabular and intertrochanteric fractures achieved bony healing in all patients.
However, fracture healing does not always equal a satisfactory prognosis. In this study, the majority (12/17, 70.6%) of patients achieved a satisfactory clinical outcome (excellent-good results, Harris score ≥ 80 points). However, there were still 5 patients with poor outcomes. Among them, 4 patients had developed avascular necrosis of the femoral head, 3 of whom converted to total hip arthroplasty. For the remaining patient, the Harris score was only 77 points. One patient developed severe posttraumatic arthritis (Kellgren-Lawrence grade 3) in her affected hip joint. It seems that the incidence of complications, especially avascular necrosis, is the main cause of poor clinical outcomes. As we know, an isolated acetabular fracture might cause avascular necrosis of the femoral head, but the incidence rate is relatively low[29, 37]. In a recent study, the incidence of avascular necrosis was 5.6% after traumatic acetabular fracture. When combined with proximal femoral fractures, the incidence rate of avascular necrosis might increase[13, 38]. It has been reported that when an acetabular fracture is identified in a patient, a combined femoral head fracture or femoral neck fracture usually indicates a greater possibility of avascular necrosis and nonunion[4, 6]. However, unlike these two kinds of fractures, an isolated intertrochanteric fracture rarely causes avascular necrosis. This kind of extracapsular fracture has only a limited effect on the blood supply of the femoral head. However, in this study, avascular necrosis was identified in 4/17 patients. We also found that dislocation of the hip joint was identified in 3 of these 4 patients. Furthermore, in our Cox regression models, dislocation of the hip joint was the sole independent risk factor for poor outcomes. Although some recent studies have shown that early reduction of the dislocated hip joint was not found to have as favorable an impact in terms of avascular necrosis[1, 13, 14], it is generally accepted that the rapid reduction of a hip dislocation is important to reduce the likelihood of avascular necrosis. This case series indicated that delayed reduction might be a potential cause of poor outcomes. In addition, we found that most cases of avascular necrosis are identified within 3 years after the injury.
We have several limitations in this study. First, this is a retrospective study with a small sample size, which may not have accounted for some important information and potential risk factors. Second, with serious injuries such as the fractures examined herein, patients often have additional injuries, but we did not account for any additional injuries in the analysis. Third, we found that hip dislocation was an independent risk factor for poor patient outcomes. However, all cases of dislocation of the hip joint were reduced several days after injury; thus, we cannot analyze whether an early reduction could be helpful in reducing the incidence of avascular necrosis and further improving the prognosis of patients.