Supra-ilioinguinal versus modified Stoppa approach in the treatment of acetabular fractures: reduction quality and early clinical results of a retrospective study

Acetabular fractures pose a great surgical challenge for orthopaedic trauma surgeons. Surgical management of displaced acetabular fracture has become the gold standard after the early work of Letournel [1]. The goals of treating an acetabular fracture are to restore the congruity and stability of the hip joint. Most should agree that anatomic reduction of weight bearing surface and concentric reduction of the hip joint is essential for long-term satisfactory results [2]. The type and nature of the acetabular fracture substantially influence which approach is used [1, 3].

The modified Stoppa approach (anterior intra-pelvic approach, AIP) allows for conveniently exposing the quadrilateral plate and the corona mortis (anastomosis of the external iliac vessel with obturator vessel) [4‐6]; however, the rectus abdominis obstructs the surgical visualization and makes reduction and fixation at a further location. Moreover, anterior fracture with the iliac crest fracture usually must be accessed by an additional window of the ilioinguinal approach [7, 8].

The ilioinguinal approach is one of the standard approaches for the treatment of acetabular fractures [9]. With this approach, the inner side of the acetabulum, especially the quadrilateral plate cannot be visualized directly during the surgery. Furthermore, it causes great trauma to the patient and is prone to complications, such as inguinal hernia [10, 11]. A new intra-pelvic approach, the supra-ilioinguinal approach, beyond the classical ilioinguinal was introduced in order to make it easier to manage the acetabular fracture involving the quadrilateral plate [12]. Unlike another similar surgical approach, the pararectus approach [13, 14], it directly incises the rectus abdominis instead of the rectus sheath, which may reduce the occurrence of iatrogenic injury of the peritoneum and abdominal wall hernia. In addition, this approach is located more laterally, no additional incisions are needed to fix the iliac crest fracture of the high anterior column fracture.

In this retrospective study, we compared the supra-ilioinguinal approach and the modified Stoppa approach for the treatment of acetabular fractures. Our specific aims were to confirm the efficacy of the supra-ilioinguinal approach through comparing the operative time, intraoperative haemorrhage, postoperative complication rates, anatomic reduction quality and hip function recovery between the two approaches.

After institutional review board approval, a consecutive cohort of 60 patients with acetabular fractures at a level 1 trauma centre from September 2014 to October 2017 were treated operatively using supra-ilioinguinal approach (group A) and modified Stoppa approach (group B), respectively. The patients were regularly followed up for at least 1 year. The distribution of the fractures according to Letournel-Judet classification is shown in Table 1. Simple posterior wall fracture and patients who were not appropriate for surgery for any other reasons were excluded. The radiographs and medical records of these patients were retrospectively analysed.

Group A contained 36 (26 males and 10 females) patients with a mean age of 43.4 (range 23–71, SD 13.6) years old; open reduction and fixation was performed using the supra-ilioinguinal approach, while modified Stoppa approach was used in group B which contained 24 (16 males and 8 females) patients with a mean age of 44.5(range 23–78, SD 14.4) years old. The mechanism of injury was traffic accident and fall from height (≧3 m). Combined injuries included pelvic fracture on the contralateral side, extremity fracture, spine fracture, pleural effusion and craniocerebral injury. The fracture patterns in group A were 4 for anterior column and/or anterior wall, 5 for transverse, 5 for T-type, 9 for anterior column with posterior hemitransverse, and 13 for both columns. The fracture patterns in group B were 3 for anterior column and/or anterior wall, 3 for transverse, 5 for T-type, 6 for anterior column with posterior hemitransverse, and 7 for both columns. The mean time from injury to operation was 7.1 (range 3–20, SD 3.4) days and 7.2 (range 3–15, SD 3.0) days, respectively. Demographic data is presented in Table 1. The operative time, intraoperative haemorrhage, perioperative complications and follow-up data were documented.

This is the first direct comparison of the surgical features, complications, radiographic and clinical results of the new supra-ilioinguinal approach and the widely used modified Stoppa approach for the surgery of acetabular fractures. In this study, operative time and the intraoperative haemorrhage of the supra-ilioinguinal approach were significantly shorter and less than the modified Stoppa approach. This result could be reasonably elucidated by the exposed clear vision and easy operation of the supra-ilioinguinal approach. The rate of complication, anatomic reduction and hip function recovery by the two approaches had no significant statistical difference. In consideration of the classic and widely used of the modified Stoppa approach [6, 7, 18] for acetabulum fracture, it would be accepted to achieve the similar fracture reduction and function recovery for the supra-ilioinguinal approach.

As with other joint fractures, it is widely recognized that the functional results of the hip and the risk of post-traumatic arthritis after surgical treatment of acetabular fractures are mainly determined by the quality of the reduction and the following solid fixation [19, 20]. Direct buttressing of the quadrilateral plate and the acetabular dome becomes urgent with the increased incidence of the elderly osteoporotic acetabular fractures [21, 22]. The supra-ilioinguinal approach provides a wide visualization from the anterior sacroiliac joint to the pubic symphysis, thus allows direct visualization of the quadrilateral plate [12]. However, there is currently no research data to support the reliability of this approach. It is difficult to compare the effects of different surgical approaches on acetabular fracture reduction, because there is no validated algorithm for the radiographic measurement of gaps and steps to assess the quality of reduction [23]. The Matta criteria is initially used for measurements on postoperative plain radiographs not on CT images. Moreover, none of the previous studies have described the details (where, what and how should be measured) for measuring residual displacement on CT images. To this end, Diederik et al. [16, 24] proposed a standard method, and their study indicates the critical cut-off value to define a poor reduction is greater for gap displacement (5 mm) but smaller for step displacement (1 mm) as assessed on CT. In general, the practice of grading acetabular fracture reduction based on CT measurements is still controversial. But we believe that the residual displacement measured by the standardized method can still reflect the quality of the reduction. On the postoperative CT of groups A and B, the mean gap was 2.3 mm and 2.1 mm, and the mean step was 0.8 mm and 1.0 mm, respectively. There was no significant difference in gap (P = 0.689) and step (P = 0.512) (Table 3). The results of large series of patients operated by the modified Stoppa approach have been reported by several authors. Sagi et al. [6] described 50 cases of which 92% had an excellent or good reduction of acetabular fractures; Anderson et al. [25] reported an 82% anatomic reduction rate and Shazar et al. [11] described 103 cases of which 82.5% anatomic reduction rate. In our study, satisfactory reduction (anatomical and imperfect reduction) rate was 88.9% in group A, while 87.5% in group B which is comparable to theirs. There was no statistical difference (P = 0.974).

There were 8 (22.2%) patients with acetabular fracture who were treated with KL approach in group A (25% were elementary), and 7 (29.2%) patients in group B (25% were elementary) were treated with an additional KL approach (Table 2), with no statistical difference (P = 0.543). Clinical results at the last follow-up were evaluated using the Merle D’Aubigne-Postel score system: 88.9% in group A and 87.5% in group B were graded good or excellent (P = 971). This is in agreement with results of previous reports [7, 11, 25].

The operative time and intraoperative haemorrhage was shorter and less of the supra-ilioinguinal approach, when the anterior approach was calculated separately, which was similar to that in other studies [11, 12]. This may be due to fewer surgical incision extensions and a more convenient reduction operation (Table 2). The modified Stoppa approach provides improved exposure of the quadrilateral surface and posterior column [6]. However, as this is a midline approach, it does not expose the iliac wing and the anterior wall of the acetabulum and cannot deal with fractures of the anterior 1/3 of the iliac bone and the anterior wall of the acetabulum. Thus, an additional lateral window (20 cases, 83.3%) of the ilioinguinal approach is required for the application of reduction clamps and insertion of posterior column lag screws through a pelvic brim plate in the supra-pectineal position.

The overall incidence of postoperative complications in the two groups (16.7% in group A and 20.8% in group B, P = 0.683) was comparable. Increased lateral iliac window may increase complications such as deep infections, although it did not occur in our study. The complication of fat liquefaction of incision was comparable, and neither patient developed a more serious infection. Prophylactic use of antibiotics may play an important role. Another important limitation of the modified Stoppa approach is the remarkable rectus tension which increases traction difficulty and may strangle the iliac vessels and lead to a high risk of injury and thrombotic lesion. In patients who underwent surgery with the modified Stoppa approach, 2 (8.3%) patients had DVT and 1 (4.2%) patient had external iliac vein injury due to excessive traction of the iliac vessels. However, only 2 (5.6%) patients had with DVT in group A. These results stress that the exposure of the iliac vessels may increase awareness of protection and improve management of vascular injury (laceration and thrombotic lesion) [7]. Most articles indicate that nerve injury is one of the frequent postoperative complications of acetabular fracture surgery, with rates ranging from 2 to 26% [6, 26]. The major nerve including femoral and sciatic nerve was not injured in our study, but there was 3 (8.3%) lateral femoral cutaneous nerve injury in group A and 1 (4.2%) obturator nerve palsy in group B. These nerve palsy recovered at 3 to 12 months of follow-up. No inguinal hernias occurred in either group.

The supra-ilioinguinal approach can easily deal with acetabular fractures involving the quadrilateral plate and the anterior wall of the acetabulum without mini-incision at the iliac crest like Keel [13, 14] used in the pararectus approach. Since the incision is quite close to the quadrilateral plate, it is more convenient to reduce and fix the fracture thus reducing intraoperative bleeding and lower the risk of complications like neurovascular injury. Compared to the modified Stoppa/iliac approach, the supra-ilioinguinal approach provides a better exposure of the anterior 1/3 of the iliac bone or sacroiliac joint injuries and enables the optimal downward reduction force to be applied in the reduction of the superior displacement of the anterior column fracture at the pelvic brim. It can be a better choice for patients with a history of lower abdominal disease like caesarean section, bladder injury or surgery. A potential disadvantage of the supra-ilioinguinal approach might be for the treatment of bilateral acetabular fractures whereas it can be operated using a single incision by the modified Stoppa approach. The supra-ilioinguinal approach is contraindicated in fractures with posterior-only patterns. It is not suitable for obese patients or those presenting with abdominal distension, ileus or bowel obstruction.

The main shortcoming of this study is that it is a retrospective study, which makes it lower in evidence level. Randomized prospective study involving a larger number of cases and long-term follow-up are needed to estimate whether the supra-ilioinguinal approach is comparable to or superior to the standard approach in terms of functional outcomes and the incidence of hip osteoarthritis.

Compared with the modified Stoppa approach, the supra-ilioinguinal approach provides a closer visualization to the quadrilateral plate, the operative time was shorter and the intraoperative haemorrhage was clearly less. It is at least equal to or could be a better choice to deal with complicated acetabular fractures especially involving the quadrilateral plate and the anterior one third of the iliac bone.