We used the Cochrane Collaboration guidelines [15
] to develop the following methods, with results reported according to the QUOROM checklist [33
]. Electronic searches of MEDLINE (1950 - present), EMBASE®
(1980–present), and the Cochrane Central Register of Controlled Trials (most recent edition) were performed in April 2009, to identify trials (Table ). Trials with the following characteristics were included: (1) randomized, quasirandomized, or controlled clinical trials; (2) patients with confirmed nonpathologic thoracolumbar (T10-L3) burst fractures based on CT and plain AP and lateral radiographs; (3) patients with no neurologic deficit; (4) comparison of nonoperative and operative management (regardless of the type of treatment); (5) participants 18 years and older; and (6) full text. Trials including patient groups with neurologic deficits or examining multiple interventions were included if examined separately. There were no restrictions on language or publication date. Articles were assessed independently by two authors (SRG, SA). When inclusion was unclear based on abstracts, full text articles were retrieved. Disagreements were resolved by discussion, and a third investigator (IAH) acted as arbitrator when necessary.
The following outcomes were extracted at baseline and last followup where available: Primary outcomes: (1) pain, measured using subjective scales, eg, VAS (0–100, 0 = no pain, 100 = worst pain); (2) function and quality of life, measured using validated indices eg, RMDQ (0 = no disability, 24 = severe disability) [39
] and Greenough Low Back Outcome Score (0 = severe disability, 75 = no disability) [23
]. Secondary outcomes assessed were: (1) return to work; (2) kyphosis progression, measured in degrees based on radiographic evaluation; (3) spinal canal stenosis progression determined by CT evaluation of the percentage of canal compromise at the midsagittal spinal canal diameter at the fracture level; (4) complications, divided into general (eg, thromboembolism, pneumonia, wound infection, urinary tract infection), neurologic deterioration, and need for later surgery; (5) costs, and (6) length of hospital stay (days).
Data extraction was performed independently by two authors (SRG, SA), and included data regarding study type, participants, methods, interventions, and outcome measures. Data were managed using Review Manager (RevMan) 5 software (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). If reported data were inadequate, we attempted to contact authors for supplementary information. We contacted Shen et al. [43
] and Hitchon et al. [26
] to obtain individual patient data, and Siebenga et al. [45
] regarding the outcomes of patients who had neurologic complications in the nonoperative group, but we received data from only the latter. Data were extracted using an intention-to-treat basis to include original study participants, where possible.
A quality assessment of each trial was performed independently by two authors (SRG, SA), with disagreements resolved by discussion. This included evaluation of allocation sequence, allocation concealment, blinding, loss to followup, and completeness of outcome reporting [15
] (Table ).
Descriptive statistics were used for baseline trial characteristics. VAS pain, RMDQ score, kyphosis, and return to work were pooled where data were available from at least two trials. When individual patient data were available, data were analyzed by intention-to-treat before pooling of outcomes was performed. Mean differences were used for continuous outcomes and odds ratios for dichotomous outcomes. Appropriate measures of precision were extracted for the purposes of this analysis including standard error, standard deviation, p value, or a 95% confidence interval. Meta-analysis was performed using the random effects model. The inverse variance method was used for continuous outcomes and the Mantel–Haenszel method for dichotomous outcomes. Our main analyses present data only from RCTs. We performed sensitivity analyses by including data from nonrandomized studies to explore whether our findings for pain, function, and deformity were robust. We also chose a priori to perform a sensitivity analysis using fixed-effects meta-analysis, which does not adjust for any statistical heterogeneity found. Heterogeneity (a measure of between-study differences that are not attributable to chance) was estimated using the I2 statistic. Results were reported with corresponding 95% confidence intervals and p values. STATA version 10.1 (StataCorp, College Station, TX, USA) was used for analyses.
We identified four trials that satisfied our inclusion criteria: two RCTs [45
], one quasiRCT [45
], and one controlled clinical trial [26
] (Fig. ). An overview of each study is provided, with sample sizes reflecting the number of patients at the start of each trial, including those lost to followup (Table ).
The study criteria are shown.
A multicenter RCT [45
] was performed of short-segmented posterior stabilization with pedicle screws inserted above and below the fracture level, in association with autogenous bone grafting, physiotherapy, and hyperextension orthoses (3 months) postoperatively. Autogenous bone was grafted from the posterior pelvic crista for transpedicle spongioplasty or posterolateral monosegmental fusion. Fifteen of 17 implants were removed at 9 to 12 months. This treatment was compared with bed rest (5 days minimum), hyperextension orthoses (3 months), and physiotherapy. However, this small trial was limited to a specific fracture (AO Type A3), with the unconventional inclusion of L3 (n = 3) and L4 (n = 1) fractures. The authors also admitted that failure to screen patients by MRI potentially led to missed detection of a posterior column injury in the nonoperative group, possibly skewing pain, function, and kyphosis results. Moreover, bias cannot be excluded as a result of unclear randomization, allocation concealment, and blinding. There was a small loss to followup (two of 34; 6%).
In another multicenter RCT [51
], the mode of operation was at the discretion of the surgeon, and consisted of anterior or posterior arthrodesis and instrumentation, and autologous bone grafting, without formal attempt at decompression. The posterior operative approach involved two to five levels of posterolateral spinal arthrodesis with pedicle screw-hook instrumentation and autologous iliac crest bone grafting, whereas the anterior approach involved two-level fibular and rib-strut construct arthrodesis with local autologous bone grafting and instrumentation. The method of bone grafting was not specified. Nonoperative treatment consisted of either a body cast (8–12 weeks) followed by thoracolumbosacral orthoses (4–8 weeks) or thoracolumbosacral orthoses alone (12–16 weeks). Before either surgery, cast, or orthoses, there was a period of bed rest (2–5 days). Although randomization appears adequate (computer-generated), allocation concealment and blinding are unclear. There is risk of attrition bias, with 11% loss to followup. The study group also was heterogeneous, with patients having multiple-level and single-level fractures, and multiple treatment options.
In a pseudoRCT [43
], short-segment posterior fixation (using pedicle screws above and below the fracture), autogenous bone grafting, and facetectomy were compared with a hyperextension brace (3 months). Autogenous bone was grafted from the posterior iliac crest and the bone inserted between the laminae and between adjacent transverse processes. The study was limited by a short followup (24 months) and inadequate sequence generation, with patient self-selection bias. Patients originally were assigned randomly, but seven were reassigned to nonoperative treatment after refusing surgery. Similarly, allocation concealment and blinding were unclear. There was a 4% loss to followup (three of 83) and intention-to-treat was not used in analysis. Furthermore, there was incomplete reporting of hospital charges, canal stenosis, and mechanism of injury.
In a prospective controlled clinical trial [26
], patients (n = 31) were allocated according to clinical and radiographic parameters. Criteria for nonoperative treatment included angular deformity less than 10°, residual spinal canal greater than 50% as measured on CT, and anterior body height greater than 50% of the posterior height. Operative treatment was used when angular deformity measured greater than 10° and residual spinal canal was greater than 50% of normal. Operative treatment consisted of decompression, stabilization via pedicle screws, and autologous bone fusion, followed by ambulation using polyester or acrylic thoracolumbar orthoses (3–5 months). Decompression was via a transpedicle approach, costotransversectomy, or through a lateral extraperitoneal approach. Autologous bone fusion occasionally in conjunction with allogenic banked bone was performed, although the source and method of grafting were not specified. Nonoperative treatment included recumbency (1–6 weeks) followed by ambulation wearing thoracolumbar orthoses (3–5 months). However, the heterogeneous cohort included patients with neurologic deficits, and reporting did not differentiate between patients who were neurologically intact managed operatively and nonoperatively except in terms of management costs. The neurologic status in the operative and nonoperative groups was dissimilar (p = 0.0001), with only a small number of patients who were neurologically intact treated operatively (n = 5) compared with nonoperatively (n = 26). Followups also were dissimilar with means of 21 and 9 months for the operative and nonoperative groups, respectively. Moreover, allocation concealment and blinding were unclear.
Individual patient data were available from two RCTs [45
], in which 79 patients (41 operative, 38 nonoperative) were identified (Table ). This does not include data for those lost to followup. The mean age of these 79 patients was 41.5 years, male to female ratio was 2:1, and mean followup was 47 months (range, 24–118 months). The majority of fractures were at T12-L1, accounting for 78% of fractures. Falls (44%) and motor vehicle accidents (35%) were the most common mechanisms of injury. Default quantitative analyses included data only from RCTs, whereas sensitivity analyses were performed using data from the quasiRCT.
Baseline characteristics of patients included in individual patient data meta-analysis
There was a difference in age but no between-group differences in gender, mechanism of injury, level of fracture, or length of followup (Table ). There also were no differences in baseline measurements of the main outcome measures of pain (mean difference [MD] = 0.8; p = 0.77; 95% CI, −4.4–6.0), function using the RMDQ score (MD = 0.6; p = 0.13; 95% CI, −0.2–1.3), or degrees of kyphosis (MD = 0.21; p = 0.91; 95% CI, -3.5–3.9).