Minimally invasive transforaminal lumbar interbody fusion: one surgeon's learning curve

Background contextThe published literature has not characterized the surgeon's learning curve with the technically demanding technique of a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).PurposeTo characterize based on intra- and perioperative parameters, the learning curve for one spine surgeon during his initial phases of performing an MIS TLIF.Study design/settingRetrospective analysis of a single institution and single surgeon experience with the unilateral MIS TLIF technique between July 2008 and April 2011.Patient sampleSixty-five consecutive patients, with at least 1 year of follow-up, who underwent a unilateral, single-level, index MIS TLIF for the diagnosis of degenerative disk disease or lumbar spinal stenosis with grade I or II spondylolisthesis were analyzed based on data obtained from the medical records and postoperative imaging (computed tomography).Outcome measuresPostoperative radiographic assessment of fusion at 1 year via computed tomography. Surgical parameters of surgical time (skin-skin, minutes), anesthesia time (induction-extubation, minutes), estimated blood loss (mL), intravenous fluids during surgery (mL), intraoperative complications (durotomy), and postoperative complications (pseudarthrosis, implant failure, malpositioned implants, graft-related complications) were also assessed.MethodsThe senior author's first 100 consecutive MIS TLIFs were evaluated initially. Patients undergoing revision or multilevel surgery were excluded leaving a total of 65 consecutive primary MIS TLIFs. The first 33 patients were compared with the second 32 patients in terms of radiographic arthrodesis rates, surgical parameters, and intra-/postoperative complications. A two-tailed Student t test was used to assess for differences between the two cohorts where a p value of less than or equal to .05 denoting statistical significance. Pearson's correlation coefficient was used to determine any association between the date of surgery and surgical time.ResultsAverage surgical time, estimated blood loss, intraoperative fluids, and duration of anesthesia was significantly longer in the first cohort (p<.05). There were no significant differences in intraoperative complications (two durotomies in both groups) or length of stay. There was no significant difference in postoperative complications at final follow-up based on computed tomography analysis (11 vs. 9, p=.649). In the first cohort, these complications included two cases of radiographic pseudarthrosis: one case of graft migration and one case of medial pedicle wall violation necessitating two revision surgeries. There were two cases of pseudarthrosis and one case of an early surgical site infection identified in the second group requiring three revision surgeries. Last, four cases of neuroforaminal bone growth were demonstrated, two in each cohort. Pearson's correlation coefficient demonstrated a negative correlation between the date of surgery and surgical time (r=?0.44; p<.001) estimated blood loss (r=?0.49; p<.001), duration of anesthesia (r=?0.41; p=.001), and intravenous fluids (r=?0.42; p=.001).ConclusionsThe MIS TLIF is a technically difficult procedure to the practicing spine surgeon with regard to intra- and perioperative parameters of surgical time, estimated blood loss, intravenous fluid, and duration of anesthesia. Operative time and proficiency improved with understanding the minimally invasive technique. Further studies are warranted to delineate the methods to minimize the complications associated with the learning curve.     

Neuroforaminal chondrocyte metaplasia and clustering associated with recombinant bone morphogenetic protein-2 usage in transforaminal lumbar interbody fusion

Background contextRecombinant human bone morphogenetic protein-2 (rhBMP-2) is commonly used to augment posterior and interbody spinal fusion techniques and has many reported side effects. Neuroforaminal heterotopic ossification (HO) is a known cause of postoperative leg pain, but the pathohistologic composition of this material is not well understood.PurposeThe purpose of this article was to report the histologic composition of a case of HO and lumbar radiculopathy after transforaminal lumbar interbody fusion with rhBMP-2.Study design/settingThis is a case report.Patient sampleThis is a single patient case report.Outcome measuresThe outcomes considered were physician-recorded clinical, physiological, and functional measures.MethodsA retrospective review of a single patient was performed. Clinical, radiographic, and pathologic specimens were reviewed and are reported.ResultsA 69-year-old woman presented with low back pain and right leg radicular pain associated with L4–L5 stenosis and a recurrent facet cyst. After attempted nonsurgical care, she underwent an L4–L5 revision decompression with interbody and posterolateral fusions including off-label rhBMP-2. Postoperatively, her symptoms resolved for approximately 7 months but then returned in association with right L4–L5 foraminal HO. The ectopic tissue was notably larger than suggested by preoperative computed tomographic scan. It was decompressed, which then improved her symptoms. Histologic examination of the specimen revealed three discrete tissue types: a nonspecific fibrovascular stroma; immature osteoid and woven bone; and chondrocyte metaplasia with chondrocyte clustering.ConclusionsNeuroforaminal HO formation is a reported side effect associated with the off-label use of rhBMP-2 for posterior lumbar interbody fusion. The mechanism of formation and the composition of this material are not well understood but may involve a chondrocyte differentiation pathway.     

Systematic review and meta-analysis of minimally invasive transforaminal lumbar interbody fusion rates performed without posterolateral fusion

The need for posterolateral fusion (PLF) in addition to interbody fusion during minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) has yet to be established. Omitting a PLF significantly reduces overall surface area available for achieving a solid arthrodesis, however it decreases the soft tissue dissection and costs of additional bone graft. The authors sought to perform a meta-analysis to establish the fusion rate of MIS TLIF performed without attempting a PLF. We performed an extensive Medline and Ovid database search through December 2010 revealing 39 articles. Inclusion criteria necessitated that a one or two level TLIF procedure was performed through a paramedian MIS approach with bilateral posterior pedicle screw instrumentation and without posterolateral bone grafting. CT scan verified fusion rates were mandatory for inclusion. Seven studies (case series and case-controls) met inclusion criteria with a total of 408 patients who underwent MIS TLIF as described above. The mean age was 50.7 years and 56.6% of patients were female. A total of 78.9% of patients underwent single level TLIF. Average radiographic follow-up was 15.6 months. All patients had local autologous interbody bone grafting harvested from the pars interarticularis and facet joint of the approach side. Either polyetheretherketone (PEEK) or allograft interbody cages were used in all patients. Overall fusion rate, confirmed by bridging trabecular interbody bone on CT scan, was 94.7%. This meta-analysis suggests that MIS TLIF performed with interbody bone grafting alone has similar fusion rates to MIS or open TLIF performed with interbody supplemented with posterolateral bone grafting and fusion.     

Minimally-invasive technique for transforaminal lumbar interbody fusion (TLIF)

Minimal access surgical techniques have been described for diskectomy and laminectomy procedures performed through tubular exposures. Tubular exposures, however, restrain visibility to a fixed diameter and require co-axial instrument manipulation. An independent blade retractor system has been developed to overcome the obstacles of working through a tube. Decompression and circumferential fusion can be accomplished through this minimal access exposure via a combination of laminectomy and transforaminal lumbar interbody fusion (TLIF) coupled with minimally invasive pedicle screw fixation. Herein, we describe a minimally-invasive technique for TLIF exposure. Illustrations, intraoperative photographs, and fluoroscopic images supplement this technique. We found that the described minimally-invasive system provides comparable exposure to the traditional-open techniques with the benefits of minimally-invasive techniques. Additionally, it does not have the added constraints of a tubular system. We were able to perform TLIFs without any additional complications. Minimal access decompression and TLIF can be performed safely and effectively using this minimally-invasive system. Besides the retractor system, no additional specialized instruments are required. An operative microscope is not required, in fact, all our cases were performed using operative loupes. The light attachment provides superb visbility without the discomfort of having to wear a headlight. Thus far we have found no added risks or complications using this system. We are currently working on long-term analysis and follow-up to further evaluate this systems efficacy.     

Awake spinal fusion

‘Awake spinal fusion’ is a novel approach to spine surgery that combines modern anaesthetic and surgical technique resulting in improved patient satisfaction and overall outcomes. Along with techniques of regional anaesthesia, minimally invasive or endoscopic surgical techniques are used to minimize surgical dissection and blood loss. Although, it is a relatively new concept with limited supporting evidence till date, it may prove to be highly effective in reducing post-operative hospital stays, in-hospital complications and cost of surgery while at the same time expediting recovery and rehabilitation. The current review focuses on techniques, advantages, limitations and the available evidence on awake spinal fusion.     

改良TLIF技术治疗腰椎管狭窄症的早期疗效研究

目的探讨在保留脊柱棘突韧带复合体的基础上,改良后的TLIF技术治疗退行性腰椎管狭窄症的疗效。方法回顾性分析我们2009年8月～2011年3月,采用改良后的TLIF技术治疗28例患者,其中男13例,女15例,病程6个月～7年;年龄43～75,平均9．2岁,其中L2/3间隙2例;L3/4间隙17例;L4/5n间隙15例;L5／S1间隙2例;伴L4椎体Ⅰ°滑脱6例;伴cobb角大于15。的退变性腰椎侧凸3例。根据术前影像学资料,三节段融合1例、二节段融合19例、单节段融合9例。全部进行椎弓根钉棒系统内固定,双侧开窗减压,完整保留棘上韧带、棘间韧带,切除增生黄韧带及部分增生内聚的小关节突,突出的椎间盘组织,椎间隙以行自体骨并单枚Cage融合。术中注意保证棘突、棘上韧带及棘间韧带的完整性。术后1-3天佩戴腰围下床活动。结果术后平均随访14个月,术前术后JOA改变量及VAS评分改变量有明显差异（P〈0．01）,随访x线片显示椎间植骨融合良好,无明显腰椎不稳征象。内固定系统无折断和松动,滑脱复位无丢失。结论保留腰椎后侧韧带复合结构,两侧开窗切除增生骨质、黄韧带,椎间盘椎管及神经根管彻底减压的改良TLIF技术,既能解除神经组织的压迫,又保留了后侧韧带复合体的完整,不仅可以有效的保护椎管内神经组织,而且很大程度上维持了脊柱原有的生物力学基础,进一步减少了手术创伤,是治疗腰椎管狭窄症的一种有效手术方法,临床治疗效果满意。     

经椎间孔椎体间融合术治疗双节段腰椎退行性疾病的中期疗效

目的探讨经椎间孔椎体间融合术﹙TLIF﹚治疗双节段腰椎退行性疾病的中期疗效。方法自2005年9月~2009年3月,25例双节段腰椎退行性病变患者进行TLIF术治疗。其中男17例,女8例。年龄42~68岁,平均56.5岁。病程1.0~12年,平均3.4年。其中L3~L511例,L4~S114例。术前VAS评分为8.3±0.7分,ODI评分45.4±2.0分,改良Prolo评分8.5±2.1分。结果手术时间180~240分钟,平均206.2±51.5分钟。术中出血420~600 ml,平均503.2±30.5ml。住院天数14~30天,平均21.3±2.2天。所有病例随访时间2.5~5.5年,平均4.8年。术后腰背功能评分与术前比较有显著性差异﹙〈0.05﹚。改良Prolo评分优15例,良8例,可1例,差1例,总优良率92%。本组25例50个融合节段,术后1年三维CT扫描,有43个节段融合,融合率86%。术后3例发生切口浅表皮肤感染,2例连杆滑脱。无螺钉松动,断裂,假关节形成和椎间融合器下沉等并发症。结论 TLIF治疗双节段腰椎退变疾病中期疗效满意,具有较高的融合率,长期结果还需进一步随访。     

改良TLIF治疗腰椎退变性疾病

目的探讨改良TLIF治疗腰椎退变性疾病的疗效。方法用改良TLIF手术治疗L3～S1退变性疾病患者24例,共融合40个节段,其中单节段8例,双节段16例。男14例,女10例;年龄56～78岁,平均64.6岁。退变性滑脱伴椎管狭窄6例,峡不连性滑脱4例,退变性腰椎管狭窄症10例,巨大椎间盘脱出合并椎间失稳4例。术中根据病情需要,采用椎管扩大减压后切除整个下关节突,切除上关节突上部的内侧半,部分开放椎间孔后壁,椎间隙自体微粒骨打压植骨,Cage斜向中线40°方向植入椎间隙,辅以椎弓根螺钉固定完成改良TLIF。结果术中无并发症发生,24例均获得随访,时间12～20个月,平均17.4个月。所有患者于术后1年随访时均达椎体间融合,无螺钉断裂和Cage移位、沉陷。10例腰椎滑脱者滑脱完全复位并维持良好。根据JOA评分法,本组术前(13.8±4.1)分,末次随访时(24.9±3.0)分,临床改善程度达优16例,良6例,可2例,平均改善率79.5%。结论改良TLIF扩大了手术适应证,贯彻了TLIF技术的设计思想和微创理念,使操作更加简单、安全,用于下腰椎退变性疾患的治疗效果满意。