Posterior lumbar interbody fusion for degenerative spondylolisthesis: restoration of sagittal balance using insert-and-rotate interbody spacers.

BACKGROUND CONTEXT: Although satisfactory clinical outcomes have been reported for degenerative spondylolisthesis using a variety of surgical techniques, its optimal management remains controversial. Laboratory and clinical evidence is emerging that if fusion surgery is undertaken, improved short- and longer-term outcomes may be achieved by correcting any sagittal deformity present. The insert-and-rotate posterior lumbar interbody fusion (PLIF) technique, first described by Jaslow in 1946, may enable surgeons to safely and effectively correct sagittal balance through a single posterior approach. PURPOSE: To examine the clinical outcomes and determine whether the focal sagittal imbalance associated with a degenerative lumbar spondylolisthesis can be safely and effectively corrected using a posterior distraction/reduction technique and insert-and-rotate interbody fusion spacers. STUDY DESIGN/SETTING: A prospective, single-cohort, observational study of the clinical outcomes and retrospective radiological review, in a series of 34 patients with degenerative spondylolisthesis, who underwent surgery between September 2000 and October 2002. PATIENT SAMPLE: Mean age of 65.1 years (range, 35 to 82 years). Thirty-two of the 34 patients underwent surgery principally for the relief of radicular leg pain. The principal indication for the fusion was the prevention of anticipated postdecompression instability in 68% of the patients. Mean preoperative slip was 20.0% (range, 12% to 33%). Mean preoperative focal lordosis was 13.2 degrees. OUTCOME MEASURES: Patients were administered pre- and postoperative clinical outcome surveys recording Visual Analogue Pain Score (VAS), Low Back Outcome Score (LBOS), Short Form (SF)-12 and patient satisfaction questionnaires. Pre- and postoperative measurements of the percentage slip and lumbar lordosis of the involved segments were available on 17 patients. Statistical analysis was done using a two tailed, paired t test. SURGICAL METHODS: Decompressive laminectomy was followed by reduction of the spondylolisthesis using intervertebral disc space distraction and pedicle screw instrumentation. The vertebral bodies were supported with bilateral intervertebral lordotic spacers, inserted on their sides and rotated 90 degrees before placing bone graft to either side of them, within the disc space. RESULTS: Mean follow-up time was 21.2 months (range, 12-32 months). No patients were lost to follow-up. Mean preoperative measures of VAS and LBOS of 5.3+/-2.2 and 24.8+/-15.6, respectively, improved to 2.2+/-2.1 (p<.001) and 44.8+/-18.0 (p<.001) at last follow-up. Thirty-one of 34 patients (91%) considered their outcome to be good or excellent. Mean preoperative slip reduced from 20.2% to 1.7% (92% correction, p<.001). Mean focal lordosis increased from 13.1 to 16.1 degrees (26.0% increase, p=.01). There were no device-related procedural complications. Postoperatively, three patients developed an ileus and one a possible deep wound infection, which settled on antibiotics. One patient required extension of his fusion at 12 months for adjacent segment stenosis. CONCLUSIONS: This series suggests that PLIF for degenerative spondylolisthesis using an insert-and-rotate technique can yield high levels of patient satisfaction with low levels of complications and substantial deformity correction using a posterior only approach. Longer-term outcome studies are required regarding the relevance of the restoration of spinal balance.     

Posterior lumbar interbody fusion (PLIF) with cages and local bone graft in the treatment of spinal stenosis

Posterior lumbar interbody fusion (PLIF) implants are increasingly being used for 360 degrees fusion after decompression of lumbar spinal stenosis combined with degenerative instability. Both titanium and PEEK (PolyEtherEtherKetone) implants are commonly used. Assessing the clinical and radiological results as well as typical complications, such as migration of the cages, is important. In addition, questions such as which radiological parameters can be used to assess successful fusion, and whether the exclusive use of local bone graft is sufficient, are frequently debated. We prospectively evaluated 30 patients after PLIF instrumentation for degenerative lumbar spinal canal stenosis, over a course of 42 months. In all cases, titanium cages and local bone graft were used for spondylodesis. The follow-up protocol of these 30 cases included standardised clinical and radiological evaluation at 3, 6, 12 and 42 months after surgery. Overall satisfactory results were achieved. With one exception, a stable result was achieved with restoration of the intervertebral space in the anterior column. After 42 months of follow-up in most cases, a radiologically visible loss of disc space height can be demonstrated. Clinically relevant migration of the cage in the dorsal direction was detected in one case. Based on our experience, posterior lumbar interbody fusion (PLIF) can be recommended for the treatment of monosegmental and bisegmental spinal stenosis, with or without segmental instability. Postoperative evaluation is mainly based on clinical parameters since the titanium implant affects the diagnostic value of imaging studies and is responsible for artefacts. The results observed in our group of patients suggest that local autologous bone graft procured from the posterior elements after decompression is an adequate material for bone grafting in this procedure.     

路椎间打压植骨融合治疗腰椎滑脱症的临床观察

目的探讨后路椎体间打压植骨融合术治疗腰椎滑脱症的临床疗效。方法 2001年1月-2008年7月,采用后路椎体间打压植骨融合术治疗36例腰椎滑脱患者,观察术前、术后及末次随访时的滑脱角、滑脱率、椎间盘高度指数,计算术后滑脱复位率和融合率;采用日本矫形外科学会（Japanese Orthopaedic Association,JOA）评分和Oswestry功能障碍指数（Oswestry disability index,ODI）进行临床疗效评估。结果所有患者获得13～25个月随访,平均随访16.8个月。术后JOA评分和ODI均优于术前,差异有统计学意义（P〈0.05）;末次随访与术后比较,差异均无统计学意义（P〉0.05）。术后的滑脱角、滑脱率和椎间隙高度指数较术前有明显改善,差异有统计学意义（P〈0.05）;而末次随访与术后比较,差异无统计学意义（P〉0.05）。将术后与末次随访的JOA好转率和滑脱复位率分别进行比较,差异无统计学意义（P〉0.05）。所有滑脱节段全部融合,无内固定松动、断裂及神经并发症。结论后路椎体间打压植骨融合术是治疗腰椎滑脱症的有效方法之一。     

Postoperative spondylitis after posterior lumbar interbody fusion using cages

The recommended surgical options for postoperative wound infections after instrumented spine surgery include a wide debridement and irrigation with antibiotics. In most cases, implant removal is not recommended for a solid fusion. However, there are few reports on the treatment choices for persistent postoperative wound infections following a posterior lumbar interbody fusion (PLIF) using cages. This paper reviewed ten patients referred to our department, who underwent revision surgery for a postoperative, deep infection after a PLIF with cages. The surgery included an anterior radical debridement and interbody fusion with removal of all implants. The clinical and laboratory results, including a bacteriologic study for the causative organism and the radiological changes, were analyzed. All patients complained of persistent severe back pain after the primary surgery. MRSA was the main organism found in these patients (five cases). Complete bony fusion was obtained in nine patients (90%). In one patient, back pain and radiating pain prevented him from returning to his original work. Despite the anterior interbody fusion with an autogenous iliac bone graft, all cases had a complete collapse of the intervertebral disc space, without a dislodgement or collapse of the graft bone. The mean loss of the height and lordosis in the involved segment was 12.7 mm (range 4–46 mm) and 5.6° (range 0–15°), respectively. Anterior radical debridement with the removal of all implants would be an effective way to manage patients with postoperative spondylitis after a PLIF using cages.     

Biological cages

Restoring a stable anterior column is essential to achieve normal spinal biomechanics. A variety of mechanical spacers have been developed and advocated for both anterior and posterior approaches. The ability to radiographically assess the "biology" of bone incorporation in these mechanical (metal) spacers is an inherent limitation. The femoral ring allograft (FRA) and posterior lumbar interbody fusion (PLIF) spacers have been developed as biological cages that permit restoration of the anterior column with a machined allograft bone (biological cage). Test results demonstrate that the FRA and PLIF Spacers have a compressive strength over 25,000 N. The pyramid shaped teeth on the surfaces and the geometry of the implant increase the resistance to expulsion at clinically relevant loads (1053 and 1236 N). The technique of anterior column reconstruction with both the FRA and the PLIF biological cages are discussed. Clinical experience with the PLIF biological cage (10 patients) and the FRA biological cage (90 patients) has not revealed any graft migration, infection, or subsidence. Additional posterior instrumentation may increase the stability of the motion segment, but the degree of stability necessary to achieve a biological union remains unclear. The incorporation of these biological cages can be monitored by conventional radiographic techniques. The method of insertion preserves the vertebral end-plates and can be performed by a minimally invasive or standard open procedure.     

Biological cages

Restoring a stable anterior column is essential to achieve normal spinal biomechanics. A variety of mechanical spacers have been developed and advocated for both anterior and posterior approaches. The ability to radiographically assess the “biology” of bone incorporation in these mechanical (metal) spacers is an inherent limitation. The femoral ring allograft (FRA) and posterior lumbar interbody fusion (PLIF) spacers have been developed as biological cages that permit restoration of the anterior column with a machined allograft bone (biological cage). Test results demonstrate that the FRA and PLIF Spacers have a compressive strength over 25,000 N. The pyramid shaped teeth on the surfaces and the geometry of the implant increase the resistance to expulsion at clinically relevant loads (1053 and 1236 N). The technique of anterior column reconstruction with both the FRA and the PLIF biological cages are discussed. Clinical experience with the PLIF biological cage (10 patients) and the FRA biological cage (90 patients) has not revealed any graft migration, infection, or subsidence. Additional posterior instrumentation may increase the stability of the motion segment, but the degree of stability necessary to achieve a biological union remains unclear. The incorporation of these biological cages can be monitored by conventional radiographic techniques. The method of insertion preserves the vertebral end-plates and can be performed by a minimally invasive or standard open procedure.     

同种皮质骨融合支架的研制及临床应用

目的研究同种皮质骨融合支架行后路椎间融合术治疗腰椎滑脱的临床疗效。方法对12例腰椎滑脱患者,用同种皮质骨融合支架行后路椎体间融合加内固定术。根据手术前后的椎间隙高度的变化和JOA评分,观察临床疗效。结果12例均获得随访,时间3-6个月,术后椎间隙高度明显恢复,无神经系统并发症,无融合支架脱出,切口无感染,JOA评分术后改善率为93.5%。结论该手术保留的骨性终板有利于防止植入物陷入椎体,能有效地维持椎间隙高度。术中无须取自体骨,且植骨面积最大化,有利于融合,植骨内固定一次完成。同种皮质骨融合支架置入牢固,具有骨传导和骨诱导作用,手术操作简单,是一种良好的椎间融合材料。     

Outcome of one-level posterior lumbar interbody fusion for spondylolisthesis and postoperative intervertebral disc degeneration adjacent to the fusion

STUDY DESIGN: Review of the clinical and radiologic records of patients who underwent one-level posterior lumbar interbody fusion (PLIF) at L4-L5. OBJECTIVE: To determine whether adjacent intervertebral disc degeneration after PLIF affects the clinical results, and whether preoperative caudal disc (L5-S1) degeneration affects postoperative clinical results. SUMMARY OF BACKGROUND DATA: There is little reliable information in the literature regarding clinical results and adjacent disc degeneration after PLIF. METHODS: Forty-five patients who underwent L4-L5 PLIF for spondylolisthesis with more than 5 years of postoperative observation were included in this study. PLIF was performed in conjunction with posterior instrumentation. The posterior lumbar intervertebral grafting was performed using both autograft and a ceramic spacer. Intervertebral disc heights at L2-L3, L3-L4, and L5-S1 were measured before and after surgery. The patients were divided into two groups based on the presence or absence of the preoperative L5-S1 narrowing. Correlation between clinical status evaluated by the recovery rate of the Japanese Orthopedic Association (JOA) score and disc heights were determined. RESULTS: All intervertebral disc heights adjacent to the fusion decreased after surgery (P < 0.05). However, no significant correlation was seen between clinical results estimated by the recovery rate and postoperative disc narrowing. There was also no significant difference in clinical results between patients with or without preoperative L5-S1 narrowing. CONCLUSIONS: There is no evidence from the results that postoperative narrowing of the adjacent disc and preoperative narrowing of the L5-S1 disc affects the clinical outcome of L4-L5 PLIF.     

后路椎体间融合术治疗腰椎节段性不稳定

目的：探讨后路椎体间融合术(PLIF手术)治疗腰椎节段性不稳定的临床疗效，比较不同种类的椎间融合技术。方法：本组采用3种PLIF手术治疗腰椎节段性不稳定患者72例，共82个节段。其中椎体滑脱28例，间盘突出合并节段性不稳定19例，不稳定型椎管狭窄25例。3种椎间融合技术包括：单纯植骨、双侧椎问支撑器、单侧斜行椎间支撑器，术中均采用椎弓根固定系统辅助，后2种方法中在安放内置物的同时，均辅以椎间自体骨屑植骨。结果：术后随访6个月～5年8个月，平均3年6个月。4～6个月后均达骨性愈合，无固定螺钉松动、断裂及再滑脱现象。患者的腰痛、下肢疼痛症状均有明显缓解，绝大多数病人恢复原正常的工作和生活。VAS疼痛分值术前平均为7.4分，术后下降至3.1分。功能评定结果：优41例，良24例，可7例，差0例，优良率为90．28％。结论：PLIF手术是治疗腰椎不稳症的一种可靠手段，只要把握手术适应证，可以取得满意的结果。     

不同植骨融合术治疗腰椎滑脱症的疗效比较分析

目的：比较3种不同植骨融合术治疗腰椎滑脱症的疗效。方法：自2006年1月至2008年12月共收治腰椎滑脱症患者85例,男36例,女49例;年龄38～65岁,平均51.8岁。采用3种手术方法：后外侧植骨融合术32例（A组）、后路椎体间植骨融合术28例（B组）、前路椎体间植骨融合术25例（C组）。疗效评定采用Nakai评分标准,骨性融合标准采用Suk标准判断。结果：所有患者均获得随访,随访时间均不少于2年。A组：优19例,良9例,中4例;B组：优16例,良9例,中3例;C组：优14例,良8例,中3例。A、B、C组的融合率分别为68.8%（22/32）、92.9%（26/28）、92.0%（23/25）。B、C组的椎间隙高度维持及融合率均优于A组（P〈0.05）。结论：对于治疗腰椎滑脱症,前路及后路椎体间植骨融合术在椎间隙高度维持及融合率优于后外侧植骨融合术,但腰椎滑脱症病情及伴随并发症多样化,应具体根据患者滑脱类型、程度、有无椎间盘突出及神经症状等做出相应的选择。     

单侧与双侧后路椎体间融合术治疗腰椎间盘突出伴腰椎不稳的疗效比较

目的比较单侧和双侧后路椎体间融合术(PLIF)治疗腰椎间盘突出伴腰椎不稳的临床疗效。方法手术治疗51例腰椎间盘突出伴腰椎不稳患者,其中行单侧PLIF治疗26例(单侧组),行双侧PLIF治疗25例(双侧组),比较两组的手术时间、术后并发症、临床疗效满意率和植骨融合率。结果手术时间:双侧组(168±20)min,单侧组(94±18)min;术中出血量:双侧组(750±41)ml,单侧组(450±40)ml;术后输血:双侧组7例,单侧组均未输血;以上各项两组比较差异均有统计学意义(P0.05)。术中硬膜囊撕裂:双侧组1例,单侧组无。术后神经根痛加剧:双侧组2例,单侧组1例。患者均获得随访,时间14~30个月。临床疗效优良率:双侧组为84.0%(21/25),单侧组为92.3%(24/26),差异有统计学意义(P0.05)。植骨融合率:双侧组为92.0%,单侧组为96.1%,差异无统计学意义(P0.05)。结论单侧PLIF治疗腰椎间盘突出伴腰椎不稳创伤小,并发症少,临床疗效满意率优于双侧PLIF。     

后路椎弓根固定270°椎间融合治疗腰椎滑脱

目的探讨经后路单侧后外侧融合基础上,单枚BAKcage斜向置人或后路椎体间植骨融合的270°融合治疗峡部裂型腰椎滑脱症的临床疗效。方法2004年8月至2007年8月,对19例峡部裂型腰椎滑脱按Meyerding分度,Ⅰ度滑脱12例,Ⅱ度滑脱7例,分别采用椎弓根螺钉复位固定单侧后外侧融合并单枚cage椎体间融合（A组）或椎弓根螺钉复位固定单侧后外侧融合并椎体间植骨融合（B组）两种270。融合方法治疗。结果19例病人术后随访时间12～24个月,平均18个月。joA评分总体满意率为95％,其中A组为100％,B组为91．7％,两者无显著性差异。19例病人均完全复位,随访复位无明显丢失。所有病人均无内固定松动断裂、cage明显后移沉降和神经根及马尾损伤等并发症。全部病人术后1年随访均获得骨性愈合。最终随访椎间隙高度平均减少1．2mm,B组较A组明显。结论两种后路270。植骨融合方式加椎弓根螺钉复位固定治疗峡部裂型腰椎滑脱对后柱破坏少,具有较高稳定性,均能获得满意疗效并能明显降低内固定松动断裂和复位丢失率,提高脊柱融合率。     

Posterior lumbar interbody fusion

This paper reports the posterior lumbar interbody fusion (PLIF) that has been performed on fourteen patients. It includes 6 cases of spondylolytic spondylolisthesis, 3 cases of degenerative spondylolisthesis, 2 cases of postoperative recurrence of lumbar disc protrusion, 2 cases of unstable prolapse of intervertebral disc, 1 cases of consequent spinal canal stenosis after lumbar lamina fusion. As a result 92 per cent of the operations are successful. The method of operation and it's modification are reported in detail. The indication of operation and the evaluative criteria of interbody bone union discussed. The intact of lumbar posterior structures, the condition of bone grating bed, the quality and disperse of bone graft are main factors that influencing bone union. Bleeding from venous plexus of spinal canal and from vertebral cancellous bone, injury of lumbosacral nerve root and cauda equina are the main surgical complications that should be stressed.     

Preliminary experience with anterior cervical microdiscectomy and interbody titanium cage fusion (Novus CT-Ti) in patients with cervical disc disease

BACKGROUND: Although the use of intervertebral fusion after anterior microdiscectomy in cervical disc disease remains controversial, a new surgical device is proposed for use in intervertebral fusion instead of bone graft. METHODS: This retrospective study at the Department of Neurosurgery, Cardarelli Hospital, Naples, from January 1993 to December 1998, compares the results of surgery on 58 patients with anterior microdiscectomy and intervertebral bone graft fusion (Group A) (ADIBG) with a group of 52 patients who underwent anterior microdiscectomy and intervertebral titanium cage fusion (Group B) (ADITC) in cervical radiculopathy and spondylotic myelopathy.In both groups a "radical discectomy" was performed under the operating microscope. In group A, interbody fusion was performed with autologous tricortical bone graft. In group B, a new type of titanium device (Novus CT-Ti) was used (Sofamor Danek Group). RESULTS: There was no collapse or extrusion of the device and no complications at the donor site (the bone fragments used to fill the cage were taken from osteophytes or vertebral body fragments).The use of this device provides immediate stabilization, reduces or eliminates pain, promotes bone fusion between the vertebrae adjacent to the cage by allowing bone growth through the cage, reestablishes and maintains the intervertebral space, reduces the average hospitalization time, and allows a quicker return to work. CONCLUSIONS: Patients who underwent ADITC did well and benefited from the surgery. Those who underwent ADITC did better than those who underwent ADIBG in regard to function, relief from pain, and complications.Early and good stability of the cervical spine seems to be the main advantage of using titanium cages.     

后路椎体间打压植骨治疗老年人腰椎退变性疾病的临床报道

目的 探讨椎体间微粒骨打压植骨治疗老年人腰椎退变性疾病的手术技术和初期临床疗效报道。方法 本组为2002年5月～2004年8月在对28位60岁以上老年人腰椎退变性疾病患者手术治疗的同时进行椎体间微粒骨打压植骨融合。观察手术前后的症状、体征、影像学上的腰椎前凸角、椎间隙高度指数的变化,以及手术后CT检查椎体间植骨面积,同时随访6～26个月观察初期临床疗效和融合率。结果 几乎所有患者手术后原症状和体征均得到缓解,影像学上的腰椎前凸角、椎间隙高度指数都有明显恢复,手术后6～26个月,脊柱融合率达到96．4％。没有发生植入骨的吸收、移位和沉陷。并发症主要为术中硬脊膜撕裂、神经根牵拉以及出血多等。结论 后路减压、固定、椎体间微粒骨打压植骨融合治疗老年人腰椎退变性疾病早期临床疗效满意。     

退行性脊柱侧凸的手术治疗及相关文献回顾

目的　在回顾手术治疗退行性脊柱侧凸进展的基础上 ,探讨椎弓根螺钉系统在退行性脊柱侧凸矫治的策略 ,并评价其疗效。方法　 1999年 7月～ 2 0 0 2年 7月 ,本院骨科连续治疗 32例退行性脊柱侧凸患者 ,其中 7例先行一期前路脊柱松解 ,二期后路多节段椎弓根螺钉矫形 ,后外侧植骨融合 ;16例行后路椎管减压、PLIF椎体间支撑融合、椎弓根螺钉矫形内固定、后外侧植骨融合术 ;9例行后路椎管减压、椎板截骨短缩、椎弓根螺钉矫形内固定、后外侧植骨融合术。结果　本组围手术期没有出现切口感染 ,2例术后出现肺部感染症状 ,4例出现症状对侧的下肢痛 ,经过对症处理后好转。本组全部病例随访 18个月～ 3年 ,平均 2 .4年。全部病例无断钉、断棒 ,无交界性后凸。术前、术后及 18个月随访时进行Oswestry评分 ,统计结果表明术后和 18个月随访时ODS评分与术前有显著性差异 (P >0 .0 5 )。结论　在充分减压的前提下 ,椎弓根螺钉三维矫正技术对退行性脊柱侧凸可达到满意的纠正 ,重建脊柱稳定性 ,适当的前路松解和椎体间支撑性植骨有利于矢状面畸形的改善 ,减少神经并发症的发生     

Outcome of single level instrumented posterior lumbar interbody fusion using corticocancellous laminectomy bone chips

Background:

Interbody fusion surgery has been considered by many to be a treatment of choice for instability in lumbar degenerative disc disease. A posterior lumbar interbody fusion (PLIF) has the advantages of spinal canal decompression, anterior column reconstruction, and reduction of the sagittal slips from a single posterior approach. The PLIF using double cage was a standard practice till many studies reported comparable results and lesser complications with single cage. Iliac crest was considered as an appropriate source of bone graft until comparable spinal fusion rates using local bone graft and cage emerged. Till date, there has been no report of corticocancellous laminectomy bone chips alone being used for spinal fusion. In this paper, we present radiologic results of single level instrumented PLIF, where in only corticocancellous laminectomy bone chips were used as a fusion device.

Materials and Methods:

It is a retrospective cohort study of 35 consecutive patients, who underwent single level instrumented PLIF surgery, wherein only locally obtained bone chips was used for spinal fusion. The average follow-up was 26 months. The indications for the surgery were as follows: 19 patients had disc herniations, with back pain of instability type, normal disc height on radiology. Ten patients had grade 1 spondylolisthesis, with significant back pain and translational instability on radiography. Three patients were redo spine surgeries, and three patients had healed spondylodiscitis with significant back pain and instability. All patients were regularly followed up and decision of spinal fusion or no fusion was taken at 2 years using modified criteria of Lee.

Results:

Of total 35 patients, there were 24 males and 11 females, with a mean age of 41 years. There were 16 patients with definitive fusion, 15 patients with probable fusion, 04 patients with possible pseudoarthrosis, and no patient had definitive pseudoarthrosis. The mean time for fusion to occur was 18 months. The average loss of disc height, over 2 year follow up, was only 3 mm in 8 patients. Three patients had a localized kyphosis of more than 3° at the fusion level. The average blood loss was 356 ml and average operating time was 150 min.

Conclusion:

Corticocancellous laminectomy bone chips alone can be used as a means of spinal fusion in patients with single level instrumented PLIF. This has got a good fusion rate.     

Posterior lumbar interbody fusion for lytic spondylolisthesis: restoration of sagittal balance using insert-and-rotate interbody spacers.

BACKGROUND CONTEXT: The role of surgical correction of sagittal plane deformity in cases of lytic spondylolisthesis remains controversial. While some early evidence is emerging of the possible short- and long-term benefits of restoring spinal balance, many surgeons have been concerned about the associated risks. The insert-and-rotate posterior lumbar interbody fusion (PLIF) technique, first described by Jaslow in 1946, may enable surgeons to safely and effectively correct sagittal balance through a single posterior approach. PURPOSE: To determine whether the focal kyphosis and subluxation associated with a lytic lumbosacral spondylolisthesis can be safely and effectively corrected using a single-stage posterior distraction/reduction technique and insert-and-rotate interbody fusion spacers. STUDY DESIGN/SETTING: A prospective, single cohort, observational study of the clinical outcomes and retrospective radiological review, in a series of 18 consecutive patients with lytic spondylolisthesis Grades I to IV, operated between September 2000 and December 2002. PATIENT SAMPLE: Mean age of 50.2 years (range, 15.5 to 77.8 years). Principal indication for surgery was relief of radicular pain secondary to foraminal stenosis in 16 of 18 patients, and back pain was the principal symptom in 2 patients. Mean preoperative slip was 30.2% (range, 9% to 78%). Mean preoperative focal lordosis was 10.6 degrees (range, -12 to 33 degrees). OUTCOME MEASURES: Minimum 12-month follow-up was available on all patients except one, who died of unrelated causes after his 6-month visit. Patients completed Visual Analogue Pain Score (VAS), Low Back Outcome Score (LBOS), Short Form (SF)-12 and patient satisfaction questionnaires. Pre- and postoperative measurements of the percentage slip and lumbar lordosis of the involved segments were available on 13 patients. SURGICAL METHODS: Decompressive laminectomy was followed by reduction of the spondylolisthesis with the aid of intervertebral disc space spreaders and supplementary pedicle screw instrumentation. The vertebral bodies were supported with bilateral intervertebral lordotic spacers made from carbon fiber, titanium mesh or polyether-ether-ketone (Medtronic Sofamor Danek, Memphis, TN). These were inserted on their sides and rotated 90 degrees before placing bone graft to either side of them, within the disc space. RESULTS: Mean follow-up was 17.3 months. Mean preoperative measures of VAS and LBOS of 5.0+/-2.3 and 29.3+/-16.4, respectively, improved to 2.9+/-3.0 (p=.01) and 42.6+/-20.1 (p=.005) at last follow-up. Fifteen of 18 patients (83.3%) considered their outcome to be good or excellent. Mean preoperative slip reduced from 30.2% to 6.2% (p=.001). Mean focal lordosis improved from 10.6 to 18.1 degrees (p=.02). Lumbar lordosis (L1-S1) did not change, but the lordosis of the lumbar segments above the fusion reduced from 46.8 to 34.9 degrees (p=.02). There were no serious implant or procedural complications. Postoperatively, there was a delayed and temporary weakness of ankle dorsiflexion in a patient with Grade IV spondylolisthesis. CONCLUSIONS: This series suggests that PLIF using an insert-and-rotate technique can yield satisfactory clinical outcomes and substantial deformity correction using a posterior only approach and with low levels of serious or permanent complications. Longer-term clinical outcome and comparative studies are required regarding the importance of the restoration of spinal balance.     

Are 2 cages needed with instrumented PLIF? A comparison of 1 versus 2 interbody cages in a military population

Bovine biomechanical data have demonstrated adequate stability of a single threaded interbody cage when combined with a unilateral facet screw during posterior lumbar disc excision and interbody fusion (PLIF). Instrumented PLIF surgery using 1 versus 2 interbody cages was studied in 35 military men with disc disease and chronic low back pain. All patients underwent instrumented PLIF with bilateral diskectomy and partial facetectomy, pedicle screws, autogenous iliac crest bone graft, 1 or 2 interbody cages, and posterior lateral fusion. After an average of 15 months' follow-up, the 2-cage group had a higher rate of dural tear, but rates of other complications, hospital stay, fusion rates, pain levels, functional outcomes, and patient satisfaction were good and did not differ between groups. Costs were higher for the 2-cage group by 1728 dollars per patient.     

Experience in posterior lumbar interbody fusion: unicortical versus bicortical autologous grafts

Over the past seven years, 96 PLIF operations were performed with the autologous bone graft method. In 44 cases, unicortical bone grafts were obtained from the posterior iliac crest area. In the remaining 52 cases, bicortical bone grafts were obtained from the anterior iliac crest. The failure rate in the patients treated by interbody fusion with the unicortical posterior iliac crest graft was 11.8%. The failure rate in patients treated by interbody fusion with bicortical bone grafts was only 1.9%. The patients were ambulatory three to four days after the operation. In cases of spondylolysis and spondylolisthesis, interbody fusion should be coupled with some manner of posterior internal fixation. The extraction of two pieces of bicortical bone from the anterior iliac crest, measuring 1.2 cm or 1.3 cm by 2.5 cm, may cause weakness of the pelvic bone. Therefore, the bicortical grafting in PLIF should be limited to severely disabled patients with complete spinal canal stenosis or very large myelographic defects.