Letter to the Editor concerning "ALIF and total disc replacement versus 2-level circumferential fusion with TLIF: a prospective, randomized, clinical and radiological trial" by Hoff EK, Strube P, Pumberger M et al. (2015). Eur Spine J. Mar 7. [Epub ahead of print

Abstract

We read the article by Eike K. Hoff [1] with great interest. We would like to compliment the authors for their work. As we know, single-level stand-alone ALIF in combination with TDR is a novel surgical technique to treat degenerative disc disease at L4–S1. Although this study has greatly improved our knowledge, we do have some concerns about the study. First, we found that provocative discography was employed to prove the discogenic pain of L4/5. Although discography has the potential to assist in diagnosing disc derangement, consideration of the consistent reports of the high false-positive rates and new findings of accelerated degeneration in discs that undergo discography make it difficult to recommend the procedure for the diagnosis of discogenic back pain. There is evidence to suggest an association between advanced degenerative spondylosis and a history of undergoing provocative discography [2]. The validity of lumbar discography is very much in doubt, which is underscored by a more recent practice recommendation published by the American Pain Society, which suggested that provocative lumbar discography should not be used for making the diagnosis of a discogenic source of pain in the setting of low back pain [3]. The new guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine showed that based primarily on retrospective studies, discography, as a standalone test, is not recommended to formulate treatment strategies for patients with low back pain [2]. However, we found the patients in this study were enrolled from June 2007 through November 2010. It is recommended that discoblock be considered as a diagnostic option during the evaluation of a patient presenting with chronic low back pain in the future according to the guideline [2]. Second, in this study, the fusion rate was estimated employing both plain and extension–flexion radiographs. The fusion criteria were not clearly described. Lack of substantial sclerotic changes in the recipient bone bed, visible bridging bone either through the cage or surrounding it as observed on anterior–posterior or lateral radiographs are criteria from some other studies. And also, it has been demonstrated that CT scan is essential to assess interbody fusions [4]. We have tried to employ X-ray to evaluate the PEEK-cages interbody fusion rate, but finally a thin-layer slicing CT scan had to be performed in the cases where bone fusion on plain radiographs was in doubt [5]. Finally, arthrodesis is a traditional surgical technique and has been regarded as established gold standard for the surgical treatment of refractory low back pain due to lumbar degenerative disc disease. TDR has been proved to have obvious and significant drawbacks in more ways than one. Combined ALIF at L5/S1 and TDR at L4/5 is a relatively new surgical alternative. Though the author concluded that it is a viable surgical alternative for the treatment of two-level DDD in comparison with two-level circumferential fusion, it is strongly recommended that additional long-term follow-up studies are needed to further justify its wide use. & Jianqiang Ni njqspine@163.com