Comparative study between anterior symphyseal platting and percutaneous symphyseal screws for treatment of traumatic symphyseal diastasis

Symphyseal diastasis accounts for 13–16% of pelvic ring injuries [1]. Symphyseal diastasis, or fracture of the superior and inferior pubic rami, whether on one side or both, are signs of failure of the anterior pelvic ring [20]. Disruption of the symphysis pubis will cause pelvic ring instability and is a consistent indication of anterior pelvic ring fixation if the symphysis pubis diastasis is more than 25 mm [14, 20]. According to the Young and Burgess Classification System, symphysis diastasis results from anteroposterior compression injury (APC) [9]. Surgical treatment of unstable pelvic fractures aims to restore pelvic stability through accurate anatomic reduction and stable pelvic fixation. The stable pelvic fixation will reduce the pain and allow the patient early ambulation and early return to work. It will decrease patient morbidity, which ranges from 5 to 20% following pelvic fractures [21, 34]. Adequate reduction and fixation of the displaced symphyseal disruption is essential to restore stability and alignment of the pelvic ring. The anterior pelvic ring provides about 30% of pelvic stability [3]. Plating is the standard method of fixation of symphysis diastasis. Other methods of fixation are tension band wiring (two cancellous bone screws and wire loops) and absorbable suture materials [9, 15]. Open osteosynthesis of the symphysis pubis through conventional plates is not a complication-free technique. Its advantages are open reduction, and plating allows direct anatomic reduction, improved stability, and low morbidity and does not routinely require implant removal. Its disadvantages are extensive exposure, which may lead to complications such as blood loss, bladder injury, neural or vascular injury, wound healing problems, and heterotopic bone formation [5]. Fixation failure for symphysis plating ranges from 12 to 75%, loss of reduction occurs from 7 to 24%, and revision rates range from 3 to 9% [5, 7, 23]. To reduce these complications, several other techniques have been reported, including external pelvic fixation, percutaneous cannulated screw fixation, and minimally invasive plate osteosynthesis. Recently, percutaneous reduction and fixation of pelvic fractures have been employed to treat various pelvic ring and acetabulum injuries. The advantages of percutaneous fixation are shorter operative times, less blood loss, and lower surgical site infection rates compared to traditional open approaches [12, 21, 28]. The current study aims to compare the clinical and radiological outcomes of treatment of symphysis pubis diastasis using symphyseal plating and percutaneous symphyseal screws.

We aimed to evaluate the clinical and radiological outcomes of treatment of symphysis pubis diastasis using both methods of fixation.

Fifty patients were included in this study. Forty-three patients were males (group A: 22 males—group B: 21 males). The mean age for group A patients was 35.4 years, while the mean age for group B was 37.7.

The mechanism of injury for both groups was motor vehicle accidents in 33 cases, falling from height in 11 cases, and motorcycle accidents in 6 cases. Average days for surgery were 4.11 days for group A and 4.2 days for group B. All patients have followed up for at least two years. Table 1.

In group A, a four-holed 4.5 mm reconstruction plate was used for fixation in twenty patients while a five-holed 4.5 mm reconstruction plate was used in six cases. Regarding posterior pelvic injury, iliosacral screw was used in 15 cases, anterior iliac plating in three cases, and lateral compression screw was used in three cases (two cases from the anterior approach and one case from the posterior approach).

In group B, two partially threaded cancellous screws (diameter 7.3 mm) were used for fixation of the anterior pelvic ring in all cases. Regarding posterior pelvic injury, iliosacral screw was used in 14 cases, anterior iliac plating in two cases, and lateral compression screw was used in five cases (3 cases from the anterior approach and 2 cases from the posterior approach).

Our results were statistically significant regarding operative time, intraoperative blood loss, number of intraoperative x-ray shots, length of incision, and vertical pelvic displacement according to Henderson horizontal reference lines. Table 2.

The mean pre-operative VAS score was 9 ± 1 for group A, while the immediate mean post-operative score was 4.5 ± 1. The mean postoperative score at a minimum of two years of follow-up was 1.4 ± 0.5.

The mean pre-operative VAS score was 9 ± 1 for group B, while the immediate mean post-operative score was 4 ± 1. The mean postoperative score at a minimum two-year follow-up was 1.1 ± 0.2.

The mean post-operative symphyseal diastasis at the last follow-up for group A was 0.869, while the mean post-operative symphyseal diastasis at the last follow-up for group B was 0.612. (P value was insignificant = 0.15117). Figures 4 and 5.

There is no statistically significant difference between both groups regarding the Majeed scoring system.

Using Henderson horizontal reference lines, four cases in group A had vertical displacement of more than 1 cm at the last follow-up visit, while there were no recorded cases of vertical displacement in group B. Table 3.

Five patients in group A (19%) showed metal failure in the form of plate breakage, screw loosening, and screw backing out. Plate removal was done in three patients (11.5%), and the other two patients refused another surgery. Figure 6.

In Group B, one case showed implant failure (4%) and loss of reduction in the form of screw backing out and widening of the symphysis pubis at three months postoperatively. Screw removal was done, and application of external fixators for one month, and the patient refused to do another surgery. Figure 7.

Two patients in group A (7.5%) had infections at the incision site, which were treated with antibiotics and daily dressings and resolved adequately. No recorded cases of infection in group B. Table 4.

Open reduction and internal fixation have become the standard and preferred method for fixing pelvic and acetabular fractures. Symphyseal plating via a Pfannenstiel approach is the standard method of fixation of symphysis diastasis. Advantages of open reduction and fixation are direct anatomic reduction, low morbidity, low infection rate, low incisional hernia rates, and does not routinely require implant removal [6, 12, 17]. Its disadvantages are extensive exposure, which may lead to complications such as blood loss, neurovascular injury, wound healing problems, heterotopic bone formation, lateral incision extension in large obese patients, and this can increase the risk of damage to inguinal canal and its contents. One of the advantages of open pelvic approaches is the removal of retropubic haematoma caused by traction of the prevesical venous plexus; however, in percutaneous pelvic techniques, the retropubic hematoma was probably always absorbed without consequences, and it did not affect our results [6, 12, 17].

Percutaneous procedures, which aim to achieve anatomical reduction and shrink incisions, have recently been developed and are expected to lower open procedures’ dangers [29]. Percutaneous screw fixation in pelvic fractures has replaced traditional methods of pelvic ring fixation. The Percutaneous technique for insertion of the iliosacral screw was first described by Rout et al. [22]. The advantages of percutaneous fixation of symphysis diastasis include less blood loss, minimal invasiveness with small incision size, and short operative time with experienced surgeons. Disadvantages are excess exposure to radiation with using an intraoperative C-arm, long operative time in learning surgeons, and the need for experienced surgeons.

Traditional open reduction and internal fixation using reconstruction plates have been widely used for traumatic symphysis pubis diastasis [24, 25]. Biomechanical studies have reported that symphyseal plating is an effective method to stabilize the anterior pelvic ring [27], and satisfactory outcomes have been confirmed in published case series [10, 11, 26]. There are recent clinical trials describing the fixation of symphyseal diastasis using percutaneous screws and recommending percutaneous screws for symphysis pubis fixation [5, 9, 17, 34].

The symphysis pubis is a fibrocartilaginous joint. It consists of a disc that is positioned between the articular surfaces of the pubic bones. Under physiological settings, it can move a little bit, often by up to 2 mm and rotating 1 degree in adults. In multiparous females in particular, a larger degree of mobility can be observed [2]. Some authors stated that normal physiological movement is restricted when the pubic symphysis is rigidly fixed. The metalwork of the symphysis may eventually be stressed by physiological micro-motion, which could lead to implant failure like screw loosening or plate breaking and symphyseal diastasis. Therefore, it appears that a significant implant failure rate with a low revision rate is a unique characteristic of the plating of traumatic symphysis diastasis [2, 30].

O’Neill et al. [19] in their biomechanical study to compare percutaneous screw fixation versus plate osteosynthesis for fixation of pubic symphysis diastasis, they reported that symphyseal screws may be a viable alternative to classically described symphyseal plating.

Zheng et al. [35] evaluated the biomechanical characteristics of seven fixation methods to treat symphysis pubis diastasis using finite element analysis. They concluded that dual cannulated screw fixation is the best fixation method for traumatic symphysis pubis diastasis that offers ideal outcomes to maintain stability and prevent failure biomechanically. The single plate with crossed symphyseal screws and dual symphyseal plates methods had a better and more effective fixation method than single plate fixation.

The intramedullary method of cannulated screw fixation is responsible for its biomechanical advantage. It was previously established that intramedullary nailing had a lower failure rate than a plate and could lessen the implant’s stress load. To prevent implant failure, care had to be taken precisely where the stress was concentrated at the screw-plate contact site and in the middle of the cannulated screw [31].

In their biomechanical study, Yao et al. compared fixation of symphysis diastasis using a single plate (4-hole and 5-hole), double plates (4-hole and 5-hole), and a single screw (cannulated screw 7.3 mm diameter, double parallel screw (cannulated screw 6.5 mm diameter), and double-crossed screw (cannulated screw 6.5 mm diameter). They reported that single or double plate fixation achieved greater stiffness than single screw fixation, while double screw fixation, either in parallel configuration or crossed configuration, achieved greater stiffness than single or double plating techniques. They concluded that stabilization of the posterior pelvic ring is mandatory to restore overall pelvis stiffness [33].

Cano-Luis et al. performed a cadaveric biomechanical study to assess the use of two cannulated screws with a 6.5 mm diameter for the fixation of Tile B1 and B3 fractures. They compared the displacement of the symphysis pubis of the normal and injured pelvis (fixed with screws) under 300 N and found no difference, and the injured pelvis fixed with two screws can resist displacement and rotational forces [4].

Yu et al. performed a biomechanical study and compared fixation of symphysis diastasis with a single screw and traditional anterior plating. They found a lower maximal displacement with plating compared to single screw fixation. Their retrospective case-control study compared symphysis diastasis fixation in Tile B1 patients treated with single percutaneous screw fixation (24 patients) and traditional symphysis pubis plating (27 patients). They concluded that the two groups had no significant difference in implant failure, wound infection, or revision surgery. They observed a significant improvement in intraoperative blood loss, operative time, and scar length in the percutaneous screw fixation group [34]. Our results were similar to Yu et al. regarding significant improvement in intraoperative blood loss and operative time, but in our study, we had more implant failure in the symphyseal plate group than in the group of symphyseal screw group.

By comparing the clinical and radiological results of both groups, we found that both methods of fixation had the same functional outcome with relative superiority of percutaneous symphyseal screw group (group B) over symphyseal plating group (Group A) regarding the Majeed scoring system. This is attributed to the increased failure rate in the symphyseal plate group (five cases, 19%). The visual analogue score (VAS) was statistically significant for both groups. This is explained as fracture stability; either by plate or screw, will actually reduce the pain and improve clinical symptoms.

Regarding radiological evaluation or fracture union (in cases with posterior pelvic injury), there was no statistical difference between the two groups. Both groups had a close ratio (the symphyseal plate group was 45.4 days while the symphyseal screw group was 44.1 days). We depend on Henderson horizontal reference lines to evaluate vertical displacement of pelvic fractures. Comparing the preoperative and immediate postoperative measurements for each group was statistically significant, and this represents the residual displacement or adequacy of reduction. While comparing the immediate and last follow-up measurements, we can see the incidence of the failure rate. It was insignificant for group B, but it was significant for group A, and this was affected by the incidence of failure rate in group A.

Comparing the postoperative measurement at last follow-up for both groups was statistically significant, and this means that the failure rate of symphyseal plating (Group A) is higher than that of symphyseal screws (Group B).

The most observed differences between both groups are the amount of intraoperative blood loss, operative time, length of incision, number of x-ray shots (representing x-ray radiation exposure), and vertical displacement of pelvic fracture. It was highly significant between both groups. The small amount of intraoperative blood loss in symphyseal screw fixation (Group B) is attributed to the small incision of screw insertion compared to the large incision needed in the symphyseal plate group (Group A) to do the reduction of symphysis diastasis and place the four holed or five holed reconstruction plate. The operative time was long in the first three cases in the symphyseal screw group (Group B), and it shortens gradually with increased surgeon experience and familiarity with the technique, and finally the operative time in the symphyseal screw group (42.3 min) is shorter and significantly less than in the symphyseal plate group (Group A) (58.3 min).

The surgery with symphysis pubis reduction and percutaneous fixation of screws is dependent mainly on intraoperative C-arm X-ray fluoroscopy, hence more radiation exposure than symphysis pubis plating. However, this is one of the limiting factors for the use of percutaneous screw fixation. Small-sized skin incision is one of the percutaneous technique benefits (Group B). It was statistically significant between both groups.

Wound infection was observed in two cases in the symphyseal plate group, while no cases of wound infection were observed in the symphyseal screw group. This can be explained by two causes: the incision size and long operative time in the symphyseal plate group. These may contribute to the relatively high rate of infection in the symphyseal plate group. Our results were similar to Mu et al. [17], Chen et al. [5], and Yu et al. [34]. They reported less intraoperative blood loss and shorter operative time and skin scar in cases of percutaneous symphyseal screw fixation.

Both methods are valid for fixation of traumatic symphysis diastasis. Both techniques yielded similar functional outcomes. Metal failure was more evident in patients treated with symphyseal plating (5 cases (19%)), and this was accompanied by more increases in vertical pelvic displacement. The percutaneous screw technique (group B) has the advantage of a short operative time, less blood loss, and minimally invasive surgery with smaller incision size than the symphyseal plating techniques. Despite the technique having the advantage of being minimally invasive, the high exposure to radiation and long operative time are considered limiting factors for applying the new technique. However, with increasing the learning curve and the experience of the operating surgeon, the time for operation and the amount of radiation exposure decreased gradually. These are the main reasons making the orthopaedic surgeons not perform percutaneous reduction and screw fixation of symphysis pubis diastasis. Patients with abdominal herniation, open wounds, irritable testis, bladder injury, and surgical site skin infection are contraindications for percutaneous symphyseal screw fixation [17]. Gentle closed reduction and a persistent urine catheter can help to avoid bladder incarceration during percutnaous symphseal pubis reduction.

Limitations of the study include a small sample size. Despite we had a satisfactory result compared to the existing studies in the literature, we encourage other authors to perform large prospective randomized trials comparing all types of symphyseal diastasis fixation to have more data on the best method of stabilization of symphyseal disruption.

Both techniques showed favorable results. The group with symphyseal plating showed a higher failure rate than the group with percutaneous screw fixation. The symphyseal screw group had shorter operative time, smaller incision, and less intraoperative blood loss than the symphyseal plating group but more radiation exposure. The symphyseal screw technique is a technically demanding technique and requires a high learning curve. It involves more radiation exposure, especially in inexperienced surgeons.