Radiographic Parameters in Diagnosis of Posterior Ligamentous Complex Injury

Background and Aim: Diagnosing the status of the posterior ligament complex (PLC) plays an essential role in the management of patients with thoracolumbar fractures. In this study, due to the inefficiency of existing imaging modalities in the accurate detection of PLC damage, we investigated the relevance of some imaging parameters to specific guidelines for rapid PLC injury detection. Methods and Materials/Patients: In this study, 50 patients with and 50 patients without PLC injury were included. MRI, CT scan, and radiographic imaging of the thoracolumbar spine (T12-L1) were evaluated. The thoracolumbar injury classification systems such as Denis, TLICS (Thoracolumbar Injury Classification and Scoring System), and McCormack Load Sharing and radiographic parameters such as Superior Inferior Endplate Angle (SIEA), Body Height (BH), Local Kyphosis (LK), Interspinous Distance (ISD), and Interpedicular Distance (IPD) were investigated in these patients for each imaging method. Statistical analysis was performed using SPSS (Version 21). Result: The ISD and LK and BHp (Body Height Posterior) were significant predictors of PLC injury. On radiographs, the mean LK with and without PLC damage was 25.67° and 20.92°, respectively (p<0.001). The ISD difference was 6.75 mm in cases with PLC damage and 2.84 mm in cases with an intact PLC (p<0.0001). In CT images, the mean LK was 25.77° in cases with PLC damage and 18.63° in cases with an intact PLC (p<0.037). The ISD difference was 4.14 mm in patients with PLC damage and 2.19 mm in patients without PLC damage (p<0.002). The BHp difference was 9.44 mm in cases with PLC damage and 11.09 mm in cases without PLC damage (p<0.002). Conclusion: The current study suggests formulating a predictive radiological index to identify PLC injury successfully. These guidelines can be very helpful in emergency room decision-makings, especially when the cost, availability, and time of performing MRI are important concerns in patients with multiple trauma.

Assessment of Interobserver Variability for CT Scan–Based Evaluation of Posterior Ligament Complex Injury in Thoracolumbar Fractures: An International Multicenter Pilot Study

Study Design: A multicenter, pilot study, for radiological assessment of thoracolumbar spine fractures was performed with the participation of 7 centers in Africa, Europe, Asia, and South America as a part of the AO Foundation network. Objectives: To determine the interobserver variability for computed tomography (CT) scan–based evaluation of posterior ligament complex (PLC) injury in thoracolumbar fractures. Methods: Forty-two observers including 1 principal investigator at each participating center performed variability assessment. Each center contributed toward a total of 91 patient images with A3 or A4 thoracolumbar burst fractures (T11-L2) with or without suspected PLC injury. Pathological fractures, multilevel injuries, obvious posterior bony element injury and translation/dislocation injuries were excluded. Ten patients were randomly selected and commonly reported CT parameters indicating PLC injury, including superior inferior endplate angle, vertebral body height loss, local kyphotic deformity, interspinous distance and interpedicular distance were assessed for variability. Observer values were compared with an experienced gold rater in spinal trauma. Analysis of variability was performed for all observers, between the principal investigators and also between observers participating in each center. Results: The studied parameters showed considerable variability in measurements among all observers and amongst all participating centers. The variability between the principal investigators was lower, but still substantial. The deviation of observer measurements from the gold rater were also significant for all CT parameters. Conclusions: CT-based radiological parameters previously reported to be suggestive of PLC injury showed considerable variability and magnetic resonance imaging verification of a PLC injury in all doubtful cases is suggested.

Short-segment decompression and fixation for thoracolumbar osteoporotic fractures with neurological deficits

Objective We assessed our results of short-segment decompression and fixation for osteoporotic thoracolumbar fractures with neurological deficits. Methods We evaluated 20 elderly patients (age, 60–89 years; mean, 73.2 years) with osteoporotic thoracolumbar fractures and neurological deficits. They underwent short-segment decompression and fixation and followed up for 40.6 (range, 24–68) months. A visual analog scale (VAS) and the Oswestry Disability Index (ODI) were used to measure back pain and disability. We also analyzed patients’ radiologic findings and neurological status. Perioperative and postoperative complications were recorded. Results At the latest follow-up, the average VAS score for back pain and ODI scores had significantly improved. The radiologic assessment showed significant improvements in local kyphosis, anterior vertebral height, and the vertebral wedge angle compared with the original measures. Neurological function also improved in 18 of 20 patients. No major complications occurred perioperatively. Our techniques included preservation of the posterior ligament complex, decortication of facet joints for fusion, no tapping to increase the screw insertional torque, pre-contouring of the rods according to the “adaptive” curve obtained from postural reduction, and postoperative spinal bracing. Conclusions Posterior short-segment decompression and fixation could be an effective surgical option for osteoporotic thoracolumbar burst fractures with neurological deficits.

The effect of posterior polyester tethers on the biomechanics of proximal junctional kyphosis: a finite element analysis

OBJECTIVE Proximal junctional kyphosis (PJK) remains problematic following multilevel instrumented spine surgery. Previous biomechanical studies indicate that providing less rigid fixation at the cranial aspect of a long posterior instrumented construct, via transition rods or hooks at the upper instrumented vertebra (UIV), may provide a gradual transition to normal motion and prevent PJK. The purpose of this study was to evaluate the ability of posterior anchored polyethylene tethers to distribute proximal motion segment stiffness in long instrumented spine constructs. METHODS A finite element model of a T7–L5 spine segment was created to evaluate range of motion (ROM), intradiscal pressure, pedicle screw loads, and forces in the posterior ligament complex within and adjacent to the proximal terminus of an instrumented spine construct. Six models were tested: 1) intact spine; 2) bilateral, segmental pedicle screws (PS) at all levels from T-11 through L-5; 3) bilateral pedicle screws from T-12 to L-5 and transverse process hooks (TPH) at T-11 (the UIV); 4) pedicle screws from T-11 to L5 and 1-level tethers from T-10 to T-11 (TE-UIV+1); 5) pedicle screws from T-11 to L-5 and 2-level tethers from T-9 to T-11 (TE-UIV+2); and 6) pedicle screws and 3-level tethers from T-8 to T-11 (TE-UIV+3). RESULTS Proximal-segment range of motion (ROM) for the PS construct increased from 16% at UIV−1 to 91% at UIV. Proximal-segment ROM for the TPH construct increased from 27% at UIV−1 to 92% at UIV. Posterior tether constructs distributed ROM at the UIV and cranial adjacent segments most effectively; ROM for TE-UIV+1 was 14% of the intact model at UIV−1, 76% at UIV, and 98% at UIV+1. ROM for TE-UIV+2 was 10% at UIV−1, 51% at UIV, 69% at UIV+1, and 97% at UIV+2. ROM for TE-UIV+3 was 7% at UIV−1, 33% at UIV, 45% at UIV+1, and 64% at UIV+2. Proximal segment intradiscal pressures, pedicle screw loads, and ligament forces in the posterior ligament complex were progressively reduced with increasing number of posterior tethers used. CONCLUSIONS Finite element analysis of long instrumented spine constructs demonstrated that posterior tethers created a more gradual transition in ROM and adjacent-segment stress from the instrumented to the noninstrumented spine compared with all PS and TPH constructs. Posterior tethers may limit the biomechanical risk factor for PJK; however, further clinical research is needed to evaluate clinical efficacy.