Heini Paul F, Gahrich Ulla, Orler Rene
Spine Service, Department of Orthopaedic Surgery, Inselspital, University of Bern, Bern, Switzerland.
J Spinal Disord Tech. 2004 Feb;17(1):8-14. doi: 10.1097/00024720-200402000-00003.
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.
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.
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.
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.
当既往手术干预失败和/或侵入性检查（椎间盘造影、小关节阻滞）无法确定或不能明确识别疼痛活动节段时，选择进行腰椎融合术的患者尤其困难。使用外固定器进行试验性固定可能模拟确定性内固定（如融合术），并有助于选择可能获得更好疗效的患者。本研究的目的是明确外固定器暂时缓解背痛是否可预测最终内固定和融合术后背痛的缓解情况。
对63例患者进行回顾性研究，这些患者在使用外固定器评估腰痛问题（索引手术）后长达6年。数据是根据患者在评估期间必须填写的一份方案从病历中收集的，并且在门诊临床调查期间检查实际情况。该方案监测疼痛（视觉模拟评分）、止痛药物使用情况和工作状态。根据前两个参数，将外固定的效果总体评估为阳性、可疑或阴性。在随访时重新评估相同参数。
38例患者的固定试验改善了疼痛状况，11例患者疼痛状况未变，14例患者疼痛加重。38例患者（与上述患者不完全相同）随后接受了确定性融合术，而25例患者未接受手术。30例试验阳性且接受手术的患者中，21例在融合术后情况改善；22例未进一步手术的患者中，8例在随访时情况改善。12例试验阴性的患者中，9例在随访时仍处于不佳状态。
外固定器作为评估腰痛患者的一种工具，是一项昂贵的措施，且有相当大的并发症风险，只有在其他任何措施都无法评估患者情况时，在特定患者中使用才合理。如果试验性固定未显示出益处，无论采取何种治疗措施，患者的情况仍将不佳。因此，外固定器评估的主要价值在于筛选出不应接受手术的患者。试验性固定阳性意味着术后至少两年有72%的机会获得满意疗效，而如果试验性固定显示有改善但未手术，有57%的机会出现一些自发改善。鉴于在我们以及其他系列研究中对这组患者（复杂病史、既往有干预措施）进行“阴性”筛选，所获得的结果似乎是可以接受的，并且在这组患者中使用这种侵入性诊断措施似乎是合理的。由于各单独组中的病例数过少，统计分析未显示出显著差异。
