Introduction

The surgical treatment of lumbosacral instabilities remains a challenge to this date. Several surgical options, including the S2 alar iliac (S2AI) screw, iliosacral screws, sacral bars and sacral plates have been developed since the Galveston technique was first described by Allen and Ferguson1,2. In 1994 the lumbopelvic fixation (LPF) was introduced by Kaech and Tranz as a combination of horizontal and vertical osteosynthesis and was later modified by Schildhauer et al.3,4. Since its first description, the lumbopelvic fixation technique has been used to treat instabilities of the lumbopelvic region and is widely established. The technique has been analyzed with regards to safety, reliability, intra- and postoperative complications, radiographical, and neurological outcome. Lumbopelvic fixation has been proven to provide high stability, allowing early weight-bearing and making this technique useful in high-grade instabilities, deformity fixations, sacral tumor resections, and displaced fracture fixation. On the other hand, the technique is criticized for its high rate of wound complications and infections5,6,7. However, the literature is lacking in studies reporting the functional outcome of patients who underwent lumbopelvic fixation. We therefore assessed the functional outcome after lumbopelvic fixation using the SMFA (short musculoskeletal functional assessment) score and performed a literature review.

Patients and methods

This study has been approved by the local ethics committee of the Ruhr-University Bochum (No. 16-5711-BR). All methods were performed in accordance with the relevant guidelines and regulations. Written informed consent was obtained from all patients. The last consecutive 50 patients who underwent a LPF from January 1st 2011 to December 31st 2014 were identified and administered the SMFA questionnaire. Inclusion criteria were: (1) patient underwent LPF at our institution, (2) complete medical records, (3) minimum follow-up of 12 months. Out of the 50 recipients, 22 questionnaires were returned. Five questionnaires were incomplete and therefore seventeen were included for analysis (Fig. 1). The following data were ascertained from the patient’s medical records: gender, age, etiology, associated injuries, American Society of Anaesthesiologists’ (ASA) classification, level of surgery, type of surgery, complications and trauma mechanism (low- vs. high-energy trauma). Low-energy trauma was defined as a result of falling from standing height or low height less than 1 m, while high-energy trauma was defined as any other type of trauma (e.g. motor vehicle accident or falling from heights).

Figure 1
figure 1

Flow diagram (SMFA questionnaires).

Full size image

SMFA questionnaire

The SMFA questionnaire is a patient-based survey that has been demonstrated to be a valid and reliable tool in the assessment of functional impairments. The questionnaire consists of 46 items within two main groups (functional and bother index) that assess functional impairment over the last week. The functional index represents daily activities, emotional status, mobility and arm-hand function. Higher scores indicate a greater degree of dysfunction or bother8,9.

Statistical analysis

Univariate analysis was performed to compare demographics, surgical characteristics, complications, and SMFA scores. To assess for statistical differences between groups an unpaired Students t-test was used when appropriate. Fisher’s exact test was performed to determine the significance of categorial data. For continuous outcomes, simple linear regression was used. Statistical significance was set at p < 0.05. Data were analyzed using SPSS version 22.0 (SSPS Inc, Chicago, IL).

Ethical approval

The study has been approved by the local Ethical Committee.

Results

In our patient population, the mean age was 60.3 years (32–86 years). Nine males (52.9%) and 8 females (47.1%) fulfilled the inclusion criteria. Follow-up averaged 26.9 months (14–48 months). Six patients (35.3%) suffered a low-energy trauma (ground-level fall or fall < 1 m) and 11 patients (64.7%) suffered a high-energy trauma (traffic accident or fall > 1 m). Patients in the low-energy group were significantly older compared to patients in the high-energy group (72.2 vs. 53.8 years; p = 0,030). Five patients (29.4%) suffered multiple injuries, fractures of the lower extremities in two cases, one fractured acetabulum, one traumatic brain injury, and one vertebral fracture. The vast majority of patients underwent a LPF from L5 to pelvis (82.4%). A bilateral LPF was performed in 12 patients (70.6%) (Table 1). Postoperative complications occurred in five cases including three wound healing complications.

Table 1 Overview SMFA score results.
Full size table

Analyzing the SMFA score, no significant gender-related differences were found in daily activities (56.4 vs. 82.2; p = 0.82), emotional score (46.8 vs. 54.0; p = 0.536), arm/hand score (31.6 vs. 40.6; p = 0.588), mobility (47.5 vs. 72.6; p = 0.127), function (46.2 vs. 63.9; p = 0.199) and bother score (53.9 vs. 64.8; p = 0.389).

Compared to patients with low-energy trauma, patients suffering from high-energy trauma showed significantly lower scores in “daily activities” (89.6 vs. 57.1; p = 0.031), “mobility” (84.7 vs. 45.5; p = 0.015) and “function” (74.9 vs. 43.4; p = 0.02). Patients with a concomitant injury had significantly higher scores in “emotional” (41.1 vs. 72.1; p = 0.002), “mobility” (50.7 vs. 80.0; p = 0.021), “function” (46.1 vs. 74.6; p = 0.009) and “bother” (50.0 vs. 79.2; p = 0.009). Patients with higher ASA score showed higher SMFA scores throughout all sub-scores. No significant differences in SMFA scores were found with respect to etiology (fall vs. motor vehicle accident), operative treatment, and complications (Table 1).

Literature review

The search term “lumbopelvic fixation or triangular osteosynthesis or spinopelvic fixation” was used in the database PubMed (access date: 06/20/20). Studies reporting the following functional outcome scores were included: SMFA, SF-36, EuroQol-6D, EQ-5D, ODI, Majeed, Hannover Pelvis Outcome Score, VAS, and/or a description of the neurological outcome. Exclusion criteria were as follows: (1) not reporting LPF, (2) biomechanical, anatomical, technical report (3) not trauma-related, (4) reviews and case reports, (5) article not available or (6) no functional outcome was reported.

This search resulted in 490 articles, of which 393 were excluded by title. After a full text review, a total 29 studies reporting functional outcome after lumbopelvic fixation remained (Fig. 2).

Figure 2
figure 2

Flow diagram (“Literature review” section) “Lumbopelvic Fixation” (access date 06/20/2020).

Full size image

Of the 29 studies, 25 were retrospective cohort analysis.

The cohort size throughout all studies was small, with a total number of included patients of 401 (223m/78f), averaging 17.2 patients per study with an average age of 34.1 years and an average follow-up of 26.5 months (Table 2).

Table 2 Mastersheet Literature Review on Functional Outcome in Lumbopelvic Fixation.
Full size table

Discussion

The aim of this study was to analyze functional outcomes after lumbopelvic fixations in patients with traumatic instabilities and discuss the results in the context of the existing literature.

SMFA

Using the SMFA, Jones et al. analyzed 15 patients (mean age 39 years, follow-up 23 months; 4/5 ISS > 15) with unstable sacral fractures treated with lumbopelvic fixation and found long-term dysfunction compared with normative SMFA. The permanent dysfunction and bother index sub scores were similar to chronic spinal disorders and lower extremity osteoarthritis10. By comparison, our results found higher scores over almost all sub-scores, suggesting a higher impairment. This might be explained by the distinctly higher mean age (60 vs. 39 years) in our cohort. Interestingly, in our cohort we found a significant higher impairment (daily activities, mobility, function) in patients suffering from a low-energy trauma compared to patients suffering from a high-energy trauma. This might also be explained by the significantly higher age (72.2 vs. 53.8 years; p = 0.030) of the low-energy group. The only other study evaluating functional outcome after lumbopelvic fixation using the SMFA questionnaire was reported by Sagi et al. The author treated 40 patients (mean age 39 years, follow-up 18 months) with vertically unstable pelvic injuries. The indexes improved from 6-months to the 12-months follow-up, but the majority of the patients were still showing higher impairment compared to the population mean. However, 37 of 40 patients were able to return to work and/or schooling7.

EQ-5D

Mobility is an important factor affecting patient’s daily activities and quality of life11,12. There are only few studies reporting quality of life in patients who underwent lumbopelvic fixation. Gribnau et al. reported 8 patients who underwent either lumbopelvic fixation with or without transsacral plating, iliosacral screw fixation, or transsacral plate osteosynthesis. The mean follow-up was 36 months in their study and life quality was measured using the EuroQol-6D. The mean EQ-VAS score was 70 (50–80). The authors reported that mood disorders, pain and mobility were influencing general health status13. Xie et al. reported on 15 patients after high-energy trauma with U-shaped sacral fractures (mean age 28.8 years) who underwent lumbopelvic fixation and sacral decompression. At follow-up (22.7 months; 9–47 months) all patients reported pain. The average preoperative EQ-5D was 0.203 (0.144–0.279) and postoperatively 0.786 (0.636–0.819)14. As already stated by Gribnau et al., the impact of the operative treatment on the long-term morbidity after unstable sacral fractures is difficult to assess due to often present concomitant injuries in those patients.

Oswestry disability index (ODI)

The ODI is a valid and widely used outcome measure in the management of spinal disorders15. De Lure reported on the use of a modified technique for lumbopelvic fixation in their series of 11 patients with lumbopelvic instabilities. Two patients showed minimal disability, four a moderate disability, and three a severe disability at final follow-up (35.5 months). In their cohort of ten patients with traumatic spinopelvic instabilities, Dalbayrak observed an improved ODI from 91.2 preoperatively to 24.4 at follow-up (39.2 months).

Majeed score/hannover pelvis outcome score (POS)

The Majeed pelvic score is a non-validated self-reported outcome score assessing five dimensions including standing, pain, work, sitting and sexual intercourse. The reported Majeed scores are mostly favorable ranging from 62 to 86.7. Three studies reported a less favorable outcome in the Majeed score. Nonne et al. reported an average Majeed score of 62. However, it should be noted that three of the five reported patients suffered a spinopelvic dissociation. Lindahl reported two studies with a fair functional outcome. Both studies consisted of polytraumatized patients with an average Injury Severity Score (ISS) of 40 and 41, respectively. For comparison, the average reported ISS among all included studies was 28.5 (Table 3). An association of traumatic spinopelvic dissociations with a high ISS scores has been described before4,13,16,17. In our series, all patients with concomitant injuries showed a significant worse outcome in five out of six dimensions (except Arm/Hand score) compared to patients without any associated injuries (Table 1).

Table 3 Majeed score/ISS score.
Full size table

The reported Pelvis Outcome Scores ranged from fair (Lindahl et al.) to good (Ayoub et al., Table 2). Ayoub et al. reported a satisfactory outcome in 67.9% of the 28 patients with displaced spinopelvic dissociation and sacral cauda equina syndrome. They analyzed factors affecting the final pelvic outcome using the Pelvis Outcome Score and showed that outcome was significantly better in patients with Roy-Camille type II fractures (vs. type III fractures), road traffic injuries, males, initial transverse fracture kyphosis angle < 40° and a primary direct decompression. Furthermore, they reported significant improvement of sacral fracture kyphosis (58.3° vs. 13.6°, p = 0.001), and no loss of reduction was observed at the final follow-up18. Lindahl et al. demonstrated a correlation between radiographical results and clinical scores. 74% of patients with “excellent” radiographical results had a good clinical outcome, whereas the majority (59%) of the patients with just a “good” radiographical result had a poor clinical outcome. The authors also observed an association of post-operative kyphosis with the POS. Patients with poor POS had significantly higher kyphosis (29° vs. 17°, p = 0.018) compared to patients with good POS19.

Gibbons score/neurological outcome

The Gibbons classification is widely used to assess neurological deficits in patients with sacral fractures and was reported in 15 out of 29 studies20. Throughout the analyzed studies, average improvement in the Gibbons classification from pre-operative status to follow-up examination was 1.0 (0.2–1.7; Table 4). Two studies reported significantly lower improvement in their cohorts. Jazini et al. excluded patients who needed open decompression from their study and Futamura’s patients already had very little neurological deficit pre-operatively (1.1).

Table 4 Gibbons classification improvements reported in the literature.
Full size table

The current literature is conflicted with respect to the question of surgical timing and the treatment of neurological deficits. Schildhauer et al. could not find an association between the timing of decompression and neurological recovery5. Lindahl et al. confirmed these results and showed that laminectomy does not improve bladder or bowel function in patients who underwent decompression19,21. Nevertheless, early and adequate fracture realignment, stabilization of the lumbosacral junction, as well as direct and indirect nerve decompression is still considered to be best medical practice. The reported occurrence of nerve injury in U-shaped sacral fractures ranges up to 94.3%22. Most authors agree that early surgical decompression, incomplete nerve injury, and stable fixation is related to better neurological results18,23. Furthermore, incomplete neurological injuries are more likely end up in full recovery. Schildhauer et al. reported that 36% of patients with one or more disrupted sacral nerve root recovered fully, whereas 86% of patients with non-disrupted nerve roots achieved a complete recovery of bowel and bladder function5. In a study by Lindahl et al. analyzing 36 patients with spinopelvic dissociation, permanent neurological deficits were more likely in patients with complete transverse sacral fracture displacement versus patients with incompletely displaced sacral fractures. They concluded the degree of initial translational displacement of transverse sacral fractures determines neurological recovery and clinical outcome19. Furthermore, several factors have been found to be not associated with neurological recovery or outcome including fracture type, soft-tissue lesion (Morel-Lavallee), mechanism of injury, surgical decompression, timing of surgery, age, and sex. These results are in contrast to those of Ayoub et al. who reported better outcomes in patients of male gender, road traffic injuries, initial transverse fracture kyphosis angle < 40°, and with a Roy-Camille type II fracture compared to a type III fracture18.

Even though other fixation options such as the iliosacral screw fixation (ISF) or the S2 alar iliac (S2AI) screw are useful options, their feasibility is limited in patients with unstable sacral fractures. In addition to the biomechanical advantages of the lumbopelvic fixation technique, which allows early weight-bearing, Kelly et al. showed, in their study comparing ISF vs. LPF in U/H-Type sacral fractures, that the LPF technique is used more often in younger patients and patients with higher Roy-Camille classification24. Therefore, we believe LPF and ISF to be synergistic tools, which are often used in different scenarios and patients.

However, reported functional outcomes suggest that patients who underwent lumbopelvic fixation for traumatic instabilities often suffer functional impairment and do not reach normative data again. Neurological deficits have a major impact on patient’s life quality. The severity of reported injury types, as well as the associated injuries in these often polytraumatized patients often do not allow an accurate pre-operative neurological examination. Furthermore, the significance of neurological recovery is questionable since reporting studies are mostly small retrospective cohort analysis with high variability in reported injuries, surgical techniques, and outcome measures16. Prospective clinicals trials with long-term follow-up represent an opportunity for further research in this area.

Limitations

This study has several limitations. The is single center study is of retrospective design and the sample size is relatively small. Therefore, important data points might have been missed and conclusions should be drawn carefully. Lumbopelvic fixation is a technique which has been used for several different indications. Patients with instabilities in this region requiring LPF often suffer from associated injuries after high-energy trauma. Furthermore, the SMFA questionnaire is limited in analyzing lumbopelvic region related impairments. Similar to the SF-36, this questionnaire only allows for general functional impairments to be clearly detected and distinguished. However, other outcome score such as the Hannover pelvis outcome scale (POS) and the Majeed score are non-validated. This is the first study focusing on an analysis of the functional outcome in patients who underwent lumbopelvic fixation for traumatic instabilities.

Conclusion

Our results suggest that patients with older age and those with concomitant injuries show a greater impairment according to the SMFA score. Several different outcome scores are used in the mostly small retrospective studies and conclusions should be drawn carefully. However, even though mostly favorable functional outcomes were reported throughout the literature, patients still show some level of impairment and do not reach normative data at final follow-up.