Failure of external spinal skeletal fixation to improve predictability of lumbar arthrodesis

External transpedicular spine fixation in severe spondylodiscitis - salvage procedure

Specific and non-specific infections of the spine are rare. Due to their potential for severe instabilities, deformities and the impairment of neurological structures, the treatment is often prolonged and needs an interdisciplinary management. The clinical presentation is uncharacteristic, therefore diagnosis is often delayed. There are no prospective randomized studies for therapy recommendation. The surgical concept includes eradication of the infection and the reliable stabilization of involved segments. This concept is successful in most cases of endogenous vertebral osteomyelitis. The therapy of the exogenous spine infections after macro and micro surgery is more difficult, due to the critical wound situation and the involvement of the posterior parts of the spine. In these cases, infection-associated instability of the anterior part is complicated by critical posterior wound conditions.

We present three cases of severe exogenous vertebral infections, where temporary external transpedicular spine fixation was used for salvage procedure, till soft tissue conditions have permitted a definitive internal stabilization.

Clinical decision making in spinal fusion for chronic low back pain. Results of a nationwide survey among spine surgeons

Objectives To assess the use of prognostic patient factors and predictive tests in clinical decision making for spinal fusion in patients with chronic low back pain. Design and setting Nationwide survey among spine surgeons in the Netherlands. Participants Surgeon members of the Dutch Spine Society were questioned on their surgical treatment strategy for chronic low back pain. Primary and secondary outcome measures The surgeons' opinion on the use of prognostic patient factors and predictive tests for patient selection were addressed on Likert scales, and the degree of uniformity was assessed. In addition, the influence of surgeon-specific factors, such as clinical experience and training, on decision making was determined. Results The comments from 62 surgeons (70% response rate) were analysed. Forty-four surgeons (71%) had extensive clinical experience. There was a statistically significant lack of uniformity of opinion in seven of the 11 items on prognostic factors and eight of the 11 items on predictive tests, respectively. Imaging was valued much higher than predictive tests, psychological screening or patient preferences (all p<0.01). Apart from the use of discography and long multisegment fusions, differences in training or clinical experience did not appear to be of significant influence on treatment strategy. Conclusions The present survey showed a lack of consensus among spine surgeons on the appreciation and use of predictive tests. Prognostic patient factors were not consistently incorporated in their treatment strategy either. Clinical decision making for spinal fusion to treat chronic low back pain does not have a uniform evidence base in practice. Future research should focus on identifying subgroups of patients for whom spinal fusion is an effective treatment, as only a reliable prediction of surgical outcome, combined with the implementation of individual patient factors, may enable the instalment of consensus guidelines for surgical decision making in patients with chronic low back pain.

Minimally Invasive Fusion and Fixation Techniques

Instrumented fusion plays an important role in treating a variety of degenerative and traumatic diseases of the spine. Traditional open techniques have been associated with a high degree of approach-related morbidity because of muscle retraction and blood loss. A variety of minimally invasive techniques have been developed for instrumentation of the entire spine. Advances in our understanding of the cellular and molecular mechanisms for stable bony fusion should promote the use of even less invasive techniques in the future.

Temporary external transpedicular fixation of the lumbosacral spine: a prospective, longitudinal study in 330 patients

STUDY DESIGN

In this study, 330 patients with incapacitating low back pain underwent temporary external transpedicular fixation (TETF) of the lumbosacral spine in a prospective trial.

OBJECTIVE

To evaluate TETF as a test for selecting suitable candidates for segmental spinal fusion.

SUMMARY OF BACKGROUND DATA

Few studies regarding TETF have been published, and contradictory results concerning predictive value and morbidity were reported.

METHODS

All patients were tested with the external fixator in two different positions: fixation and nonfixation. Before and during the test and at follow-up examination, pain was assessed on a Visual Analogue Scale (VAS). The TETF test was considered to be positive if the VAS score in the fixation state was 30 or more points lower than in the nonfixation state. Hence, a positive test would imply the decision to perform segmental lumbosacral fusion. When the reduction was less than 30 points, the test was negative. Individual pain reduction and working capacity were taken as measure of outcome.

RESULTS

Most of the patients in this study (62%) underwent spinal surgery previously. The positive and negative TETF groups were quite similar, but a large within-group variation was found. Within the fusion group of 123 patients, improvement in VAS scores and improvement in working capacity were not significantly better for the positive TETF group in comparison with the negative TETF group.

CONCLUSION

In this heterogeneous group of chronic patients with low back pain, TETF of the spine (including a placebo trial) does not appear to be of value in selecting suitable candidates for spinal fusion.

Accuracy of the clinical examination to predict radiographic instability of the lumbar spine

Forty-nine patients with low-back pain referred for flexion-extension radiographs due to suspicion of lumbar instability were studied to examine the relationship between the clinical presentation and the presence of radiographic instability of the lumbar spine. Patients had a mean age of 39.2 (+/-11.3) years, with a mean Oswestry score of 20.4% (+/-13.3). The median duration of symptoms was 78 days. All patients underwent both a radiographic and clinical examination. The reliability of the radiographic variables was high, while the reliability of clinical variables ranged from moderate to good. Twenty-eight patients (57%) had radiographic instability based on published norms. Clinical variables related to the presence of radiographic instability were age, lumbar flexion range of motion, total extension range of motion, the Beighton scale for general ligamentous laxity, and segmental intervertebral motion testing. The presence of at least 53 degrees of lumbar flexion or a lack of hypomobility with intervertebral motion testing resulted in a positive likelihood ratio of 4.3 (95% CI: 1.8, 10.6), for predicting radiographic instability. The results of this study indicate that various factors from the clinical examination are useful for predicting radiographic instability. If the findings of this study can be replicated, these clinical factors could be used to inform treatment decision-making without a sole reliance on radiographic assessment.

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 14: brace therapy as an adjunct to or substitute for lumbar fusion

Although conflicting reports have been presented in the literature regarding the utility of lumbar braces for the prevention of low-back pain, most Class III medical evidence suggests that these supports used prophylactically do not reduce the incidence of low-back pain or decrease the amount of time lost from work in the general working population. Among workers with a history of a back injury, their use appears to decrease the number of work days lost due to back pain. Lumbar braces appear to be an effective treatment for acute low-back pain in some populations. They do not appear to be effective in the chronic low-back pain population. If a brace is used, rigid braces offer some benefit over soft braces. There are no data to suggest that relief of low-back pain with preoperative external bracing predicts a favorable outcome following lumbar spinal fusion. No information is available on the benefit of bracing for improving fusion rates or clinical outcomes following instrumented lumbar fusion for degenerative disease.

The External Fixator

BACKGROUND

The selection of patients with low back pain for fusion is especially difficult when previous surgical interventions failed and/or invasive tests (discograms, facet blocks) do not allow or do not clearly identify the painful motion segment. Test fixation with an external fixator may mimic a definite internal fixation, such as a fusion, and may help select patients for a more favorable result. The purpose of the study was to clarify if temporary back pain relief by external fixation is predictive for back pain relief after final internal fixation and fusion.

METHODS

A retrospective study of 63 patients up to 6 years after evaluation of low back pain problems with an external fixator (index operation) was conducted. The data were collected from the charts based on a protocol that patients had to fill in during evaluation, and the actual state was checked during a clinical investigation at the outpatient clinic. The protocol monitored pain (Visual Analog Scale), pain medication, and work status. Based on the first two parameters, the effect of external fixation was defined as a general estimation as positive, doubtful, or negative. The same parameters were reassessed at follow-up control.

RESULTS

In 38 patients, the immobilization test did improve the pain situation, in 11 it remained unchanged, and in 14 the pain got worse. Thirty-eight patients (not identical with the above) underwent definitive fusion afterward, whereas 25 were not operated on. Twenty-one of 30 patients with a positive effect undergoing surgery showed an improved situation after fusion, and 8 of 22 patients without further operation were improved at follow-up. Nine of 12 patients with a negative immobilization test did stay in a bad situation at follow-up.

CONCLUSION

The external fixator as a tool for evaluation of patients with low back pain is an expensive measure with a considerable complication risk and only justified in selected patients when any other measure fails to assess and evaluate a patient's situation. If the test fixation reveals no benefit, the patients will remain in a bad situation whatever the therapeutic measure will be. Therefore the main value of the external fixator assessment is the selection of these patients that should not undergo surgery. A positive test fixation means a 72% chance for a satisfactory outcome at least two years after surgery, whereas without surgery the chance for some spontaneous improvement is 57% if the test immobilization did show some improvement. With respect of the "negative" selection of this group of patients (complex history, previous interventions) in our as well as in others series, the obtained results seem acceptable and the use of this invasive diagnostic measure in this group of patients seems justified. Statistical analysis did not show differences of significance as the numbers in the individual groups was too small.

Three-dimensional stabilization provided by the external spinal fixator compared to two internal fixation devices: a biomechanical in vitro flexibility study

We performed an in vitro study to investigate the stabilization (i.e. motion reduction) provided by the external spinal fixator (ESF), and to compare the three configurations of the ESF with two internal fixation techniques. Six human cadaveric lumbar spine specimens (L3-S1) were subjected to multidirectional flexibility testing in six configurations: (1) intact, (2) ESF in neutral, (3) ESF in distraction, (4) ESF in compression, (5) translaminar facet screw fixation, and (6) internal transpedicular fixation. Both the ESF and the internal fixation systems stabilized the specimens from L4 to S1. In each testing configuration, pure bending moments of flexion-extension, bilateral axial rotation, and bilateral lateral bending were applied to the uppermost vertebra stepwise to a maximum of 10 Nm. The rigid body motion between the vertebrae was measured using an optoelectronic camera system, and custom software was used to calculate the intervertebral rotations. For each applied motion in all testing configurations, the total range of motion (ROM) of L4-S1 is reported. All three ESF configurations stabilized the spine significantly when compared to the intact specimen. The ESF in compression provided significantly more stabilization in flexion-extension than the two other ESF configurations, but no other significant differences were found between the three ESF modes. In flexion-extension the ESF stabilized the spine significantly when compared with the two internal fixation devices. Only in bilateral lateral bending was the ESF inferior to internal transpedicular fixation in providing stabilization. The results of the present study suggest that the ESF provides a high degree of stabilization for preoperative assessment of selected low back pain patients. Whether other non-mechanical factors affect the pain relief experienced by the patients remains unknown.

Is there a connection between the clinical response after an external fixation test or a subsequent lumbar fusion and the pre-test intervertebral kinematics?

STUDY DESIGN

Evaluation of a possible correlation of clinical symptoms of chronic low back pain (LBP) patients before and after application of external spinal fixation (ESF) with three-dimensional motion patterns.

OBJECTIVE

To determine whether the intervertebral kinematics in chronic LBP patients correlate with pain relief after stabilization of the suspected painful segments.

SUMMARY OF BACKGROUND DATA

Chronic LBP is a complex clinical entity with mechanical, biochemical, and psychosocial components. Although clinically controversial, ESF has been shown to reduce intervertebral motion, and thus, it provides a mechanism to investigate the mechanical aspect of LBP.

METHODS

Thirty-four chronic LBP patients were tested with ESF of the suspected painful segments. The subjective pain relief experienced by the patients during the test and 2 years after spinal fusion surgery was determined, along with the Oswestry Disability Index. Before removal of ESF, the three-dimensional intervertebral kinematics of the painful segments (specifically range of motion, coupling patterns, and motion asymmetries) were analyzed with a precision optoelectronic camera system during active trunk motions. A series of linear correlations were performed between the clinical measures and the motion parameters.

RESULTS

The subjective pain relief during the ESF test was nominally, but not significantly, associated with lateral bending asymmetry ( = 0.22) and "abnormal" axial rotation-lateral bending coupling ( = 0.13). The improvement in the Oswestry Disability Index both post-test and at 2 years after lumbar fusion surgery was significantly correlated with the extension range of motion ( = 0.049 and = 0.036, respectively) and the extension-to-flexion range of motion ratio ( = 0.035 and = 0.044, respectively).

CONCLUSIONS

The "abnormal" motion patterns of chronic LBP patients did not correlate with subjective pain relief after ESF of the suspected symptomatic levels or with the midterm outcome of subsequent lumbar fusion surgery. The results suggest that preserved motion of the symptomatic segments before surgery is positively correlated with the clinical result of the subsequent spinal fusion in case of a positive ESF test result.