Feasibility of anterior pelvic ring fixation alone for treating lateral compression type 1 pelvic fractures with nondisplaced complete sacral fractures: a retrospective study

Introduction

Lateral compression type 1 (LC-1) pelvic fractures represent a broad spectrum of injuries, including minimal ‘buckle’ impaction fractures of the anterior sacrum to comminuted sacral fractures that extend to and through the posterior cortex (Khoury et al., 2008). Surgeons might consider multiple factors when determining whether a fracture of this type would benefit from surgical stabilisation. The most important factor is the surgeon’s assessment of fracture stability. However, evaluating the stability of LC-1 pelvic fractures is difficult, and it is a notable research topic in the field of pelvic stability.

Fracture stability is based on initial displacement shown on static radiographs and displacement observed on post-mobilisation radiographs (Bruce, Reilly & Sims, 2011). However, it is difficult to determine whether LC1 fractures are minimally displaced on radiographs obtained shortly after injury (Burgess et al., 1990; Oransky & Tortora, 2007). In clinical practice, pelvic fracture displacement often tends to be underestimated. It has been reported that the peak compression can be 1.3–2.2 times of the final compression appearing on images obtained in the hospital (Ma et al., 2019). Additionally, 37%–68% of LC-1 fractures are associated with clinically significant instability, and they may require operative treatment (Bruce, Reilly & Sims, 2011; Sagi, Coniglione & Stanford, 2011).

In LC-1 pelvic fractures, most sacral fractures are minimally displaced or nondisplaced (Beckmann et al., 2019). LC-1 fractures with incomplete sacral fractures tend to be stable and can be treated conservatively, but LC-1 injuries with complete sacral fractures may indicate instability of the pelvic ring (Bruce, Reilly & Sims, 2011; Lefaivre, Padalecki & Starr, 2009). As for LC-1 injuries with complete sacral fractures, operative stabilisation may be a good choice (Bruce, Reilly & Sims, 2011; Zwingmann et al., 2019).

However, LC-1 injuries have been treated with anterior fixation only, posterior ring fixation only, or anterior and posterior pelvic ring fixation (Avilucea et al., 2018). Because anterior pelvic ring injuries are usually more severe than posterior pelvic ring injuries and fixation of the anterior pelvic ring can provide enough support against the weight-bearing force, we often choose anterior fixation for LC-1 pelvic factures with complete sacral fractures in our hospital. Thus, the aim of this study was to evaluate the feasibility of anterior pelvic ring fixation alone for treating LC-1 pelvic fractures with nondisplaced complete sacral fractures. We hypothesised that acceptable functional recovery would be achieved with anterior pelvic ring fixation alone.

Methods

Results

The data of 123 patients with LC-1 pelvic fracture and complete sacral fracture were obtained from the 367 patients. All 123 patients underwent anterior pelvic ring fixation for the LC-1 type pelvic fractures and conservative treatment for the sacral fractures. Of these, 67 patients were fixed with screws, 56 were treated with open reduction and plate fixation, 53 were treated with the modified Stoppa approach, and three were treated with the ilioinguinal approach.

After contacting patients and their families, 108 responders returned to the hospital for further consultation. No differences in sex, age, ISS, mechanism of injury, and duration of hospitalisation were observed between the two groups (Table 1). Regarding the mechanism of injury, traffic crash was the main cause of injury in 39% and 40% of patients in the responder and non-responder groups, respectively. Regarding associated injuries, soft tissue injury was the most common type of injury in both groups. The responder group was followed up for an average of 18.37 (range 7–22) months, and the non-responder group was followed up for an average of 19.13 ± 10.39 months, but without the final functional outcomes. The times to weight bearing were 2.99 ± 0.93 and 3.27 ± 1.28 weeks postoperatively in the responder and non-responder groups, respectively. We evaluated the clinical healing time based on the radiographic findings, symptoms, and signs, and all fractures healed by the last follow-up. Times to healing were 14.59 ± 1.76 and 14.00 ± 1.36 weeks in the responder and non-responder groups, respectively. However, two patients showed displacement of their sacral fractures by 2 and 3 mm, respectively, upon bone union.

In 108 respondents, 9 sacral fracture lines passed through Denis zone 1, 27 through zone 1 and zone 2, 51 through zone 2 alone, and 12 through zone 2 and zone 3; 9 fracture lines were located in Denis zone 3 alone.

The average SF-12 functional score of the 108 patients was 48.22, and there was no significant difference in the SF-12 functional score between patients with unilateral pubic ramus and bilateral pubic rami fractures (P = 0.676). There was no difference in the SF-12 functional score between patients with partial and full weight bearing (P = 0.665). There was no significant difference in the SF-12 functional score between patients with ISS <15 and those with ISS ≥15 (P = 0.889). However, the SF-12 functional score was significantly higher in patients younger than 45 years (51.45 ± 9.38) than in those older than 45 years (43.52 ± 8.12, P = 0.000). In addition, the SF-12 functional score was significantly higher in patients without lower limb injury (48.95 ± 9.27) than in those with lower limb injury (42.92 ± 11.32, P = 0.035).

The average Majeed score of the 108 patients was 83.47 ± 9.23. Outcomes were excellent in 52 patients, good in 47, fair in seven, and poor in two. There was no significant difference in the Majeed score between those with unilateral pubic ramus and bilateral pubic rami fractures (P = 0.705). There was no significant difference in the Majeed score between patients with partial and full weight bearing (P = 0.692). There was no significant difference between patients with ISS <15 and those with ISS ≥15 (P = 0.805). However, the Majeed score was significantly higher in patients younger than 45 years (86.52 ± 8.12) than in those older than 45 years (79.05 ± 9.02, P = 0.000), with the former having a higher functional recovery. Additionally, the Majeed score was significantly higher in patients without lower limb injury (84.35 ± 8.42) than in those with lower limb injury (77.08 ± 12.41, P = 0.007, Table 2). A representative patient is shown in Figs. 1A–1F and Figs. 2A–2H.

Discussion

This is the first cases series that focused on isolated anterior pelvic ring fixation for the treatment of LC-1 pelvic fractures. Our study revealed that acceptable functional outcomes can be obtained for LC-1 pelvic fractures with nondisplaced complete sacral fractures by using anterior pelvic ring fixation alone.

Traditionally, it is difficult to evaluate the stability of LC-1 pelvic fractures and determine whether an LC-1 fracture requires operative treatment. Surgeons often have different opinions on the treatment of LC-1 pelvic fractures (Beckmann et al., 2014). Because of unrecognised instability, late displacement of LC-1 fractures treated nonoperatively occurs; therefore, early identification of these unstable injuries might permit earlier surgical intervention to prevent late displacement (Vaidya et al., 2012). In recent years, Sagi et al. formulated a protocol for performing intraoperative radiography to determine fracture stability (Sagi, Coniglione & Stanford, 2011) and developed a strategy using sequential intraoperative examination under anaesthesia (Avilucea et al., 2018). Those studies revealed that some LC-1 fractures show obvious instability. Unfortunately, we did not perform this stress examination to confirm the instability.

Because LC-1 fractures with complete sacral fractures may indicate instability of the pelvic ring (Bruce, Reilly & Sims, 2011; Lefaivre, Padalecki & Starr, 2009), operative stabilisation may be a good choice (Zwingmann et al., 2019). This was the primary reason why we retrospectively analysed patients with complete sacral fractures. Moreover, some studies have reported the use of anterior and posterior fixation for LC-1 fractures (Avilucea et al., 2018; Hagen et al., 2016; Zwingmann et al., 2019). However, we thought that stable fixation of the anterior pelvic ring could change the pattern of LC-1 fractures to that of nondisplaced sacral fractures, which could provide enough support against weight-bearing force. There is no risk of nerve root or blood vessel damage in the posterior approach if fixation of the posterior pelvic ring is not performed. On the basis of the aforementioned reasons, we have used anterior pelvic ring fixation alone for LC-1 pelvic factures with complete sacral fractures in our hospital for the past 5 years.

In our analysis, 15 patients were included in the non-responder group. Those patients were followed up for 19.13 months, but we could not obtain their final function because they either had an excuse (most were too busy) or did not return to the hospital. Therefore, 108 patients were included in the analysis. Functional score results showed that patients with LC-1 pelvic fractures with nondisplaced complete sacral fractures could obtain acceptable clinical results by anterior pelvic ring fixation and conservative treatment of the sacral fractures. According to the confounding factors described in previous studies (Gaffley et al., 2019; Hoffmann, Jones & Sietsema, 2012), we compared the functional outcomes in subgroups by anterior ring fractures, postoperative weight-bearing status, age, ISS, and associated injury. There was no significant functional differences in unilateral and bilateral pubic ramus fractures, in partial and whole weight bearing or ISS <15 and ≥15, between the two subgroups. Age was a confounding factor (Gaffley et al., 2019). The average SF-12 functional scores were 51.45 ± 9.38 and 43.52 ± 8.12 in patients aged >45 years and those ≥45 years, respectively. Moreover, the Majeed scores were 86.52 ± 8.12 and 79.05 ± 9.02 in patients aged <45 years and those ≥45 years, and 62 of 64 patients obtained excellent or good outcomes. Further, a study reported that lower extremity injury is an important factor affecting prognosis (Hoffmann, Jones & Sietsema, 2012). Among our 108 patients, 13 were complicated with lower limb injury with an average SF-12 functional score of 42.92 ± 11.32, whereas 95 without lower limb injury had an average score of 48.95 ± 9.27. The Majeed scores were 77.08 ± 12.41 and 84.35 ± 8.42 in patients with and without lower limb injury, respectively. These data demonstrate that patients’ age and the presence or absence of lower limb injury were important factors for functional recovery, and this finding is consistent with those of previous studies (Gruen et al., 1995; Hoffmann, Jones & Sietsema, 2012), in which young patients with isolated pelvic fractures achieved better function than older patients or those with polytrauma.

Our functional analysis did not emphasise on postoperative plain radiography or the quality of reduction but focused on the function of LC-1 facture patients treated with anterior pelvic ring fixation alone. The relationship between anatomical reduction and the prognosis of pelvic fractures has not been established in current studies (Hessmann et al., 2010; Rommens & Hessmann, 2002). Moreover, all fractures in our study healed by the follow-up, which has indirectly proven the feasibility of anterior pelvic ring fixation alone for treating LC-1 pelvic fractures with nondisplaced complete sacral fractures.

There are some important limitations to this study. Firstly, the study had a retrospective follow-up design, with only an 88% (108/123) response rate, which is low, and we do not know the outcome of 15 patients. Secondly, there was no control group for comparing the main outcome indicators, which makes the findings of this study less convincible and generalisable. Nonetheless, this was the first study to investigate the feasibility of performing only anterior pelvic ring fixation for treating LC-1 pelvic fractures. Our findings may provide a reference for future randomised clinical trials. Thirdly, although there was no significant difference in baseline data between responders and non-responders, information bias could have been introduced by the responders.

Conclusions

Our results indicate that acceptable functional outcomes can be achieved for LC-1 pelvic fractures with nondisplaced complete sacral fractures by using anterior pelvic ring fixation alone. In future studies, a control group seems necessary to further study the effect of sacral fractures on LC-1 fractures.

Supplemental Information