Comparison of titanium and polyetheretherketone (PEEK) cages in the surgical treatment of multilevel cervical spondylotic myelopathy: a prospective, randomized, control study with over 7-year follow-up

Purpose

Anterior cervical discectomy and fusion (ACDF) with titanium- or polyetheretherketone (PEEK)-cage reconstruction is widely used in the treatment of cervical spondylotic myelopathy (CSM). This study was to compare outcomes of titanium and PEEK cages in the treatment of multilevel CSM.

Methods

Between November 2002 and December 2004, a total of 80 patients with 3-level CSM were randomized in a 1:1 ratio to titanium group and PEEK group. The overall follow-up period of the patients ranged from 86 to 116 months (average 99.7 months). Clinical and radiological results were compared between titanium group and PEEK group.

Results

At the final follow-up, the clinical outcomes including JOA score, NDI score, and the excellent and good rates of clinical outcomes in the PEEK group were better than those in the titanium group. More loss of the Cobb angles and the intervertebral height was observed in the titanium group, resulting in the radiological parameters in the titanium group becoming inferior to the PEEK group at the final follow-up. Cage subsidence rates were 34.5 and 5.4 % in the titanium and PEEK groups, respectively. Fusion was observed in all patients of two groups at the final follow-up. Two patients presented with cage dislocation without clinical symptoms in the titanium group.

Conclusions

In surgical treatment of multilevel CSM, PEEK cage is superior to titanium cage in maintenance of intervertebral height and cervical lordosis, resulting in better clinical outcomes in the long-term follow-up.     

Radiological and clinical outcomes of novel Ti/PEEK combined spinal fusion cages: a systematic review and preclinical evaluation

Purpose

The primary objective of this paper was to provide a systematic review of the available clinical studies of Ti/PEEK combined cages in spinal interbody fusion surgeries, focusing on their radiological and clinical outcomes. A secondary aim was to provide a review and evaluation of the in vitro and preclinical studies reported on Ti/PEEK-coated implants.

Methods

A systematic search of the literature was performed in March 2015 via three databases: Medline, Embase and Cochrane library. The following key search terms were combined with synonyms to identify relevant articles: “spinal fusion,” “PEEK,” “titanium” and “cage.”

Results

The novelty of this intervention translates into a paucity of clinical trials, albeit the results of the seven clinical studies that met the criteria for inclusion are promising. All studies reported rate of fusion as a primary outcome. Two studies reported slightly improved fusion in the experimental Ti/PEEK combination cohort, one study identical fusion (91.7 %) and three studies excellent fusion (96, 100 and 94 %) in the Ti/PEEK cohort, although no differences reached statistical significance.

Conclusions

Clinical studies at this early stage demonstrate that Ti/PEEK implants are safe and efficacious, exhibiting similar fusion rates and clinical outcomes compared to the current standard PEEK. There is clinical evidence substantiating the improved radiographic fusion of Ti/PEEK, albeit the differences were not significant. This field is promising, gaining substantial popularity, and further clinical trials are needed in the future to establish Ti/PEEK cages as a mainstay of clinical practice.

     

Single-stage debridement and spinal fusion using PEEK cages through a posterior approach for eradication of lumbar pyogenic spondylodiscitis: a safe treatment strategy for a detrimental condition

Background

Pyogenic infections of the lumbar spine are a rare but critical pathology, yet with considerably high mortality rates. In cases indicating surgical therapy, the implantation of titanium cages or autologous bone grafts represent today's gold standard. Although non-metallic implants such as poly-ether-ether-ketone (PEEK) have proven to be advantageous in diverse degenerative conditions, their saftey and practicability in lumbar spine infection remains questionable. Moreover, the efficacy of a single-step radical debridement of the infected disc space with subsequent fusion from a strictly posterior approach continues to be an issue of debate. We therefore sought to evaluate the feasibility, clinical and radiological outcome of a single-step TLIF procedure using oblique PEEK cages in the surgical management of patients with lumbar pyogenic spondylodiscitis.

Methods

From January 2009 through December 2013, all patients meeting the indication for surgical treatment of lumbar pyogenic spondylodiscitis were included. Patients demonstrating intact cortical bone on preoperative CT received a single-step radical debridement of the infected intervertebral disc space, posterior screw-and-rod instrumentation and implantation of an oblique PEEK cage using the TLIF technique. Oral antibiotics were continued for 12 weeks postoperatively and clinical and radiological results recorded throughout a minimum 1-year clinical follow-up.

Results

A total of 104 patients were admitted to receive surgical therapy for lumbar pyogenic spondylodiscitis. Within this patient population, 18 patients met the diagnostic criteria to receive the implantation of an oblique PEEK cage. Pathogens were detected in 13 cases with Staph. aureus being the predominant causative organism. All patients were discharged to recover in their domestic environment. Throughout the first year of clinical and radiological follow-up and beyond, none of the 18 patients demonstrated any signs of residual neurologic deficits or recurrent infection. Furthermore, two-plane conventional X-rays showed no significant implant subsidence or failure at any of the given time-points in up to 5 years postoperatively.

Conclusions

In patients meeting the criteria for surgical treatment of lumbar pyogenic spondylodiscitis, the implantation of PEEK cages using a single-step TLIF approach is a safe and feasible procedure. Based on our experience, the concern of a recurrent infection when implanting non-metallic cages may be refuted in carefully selected patients.

     

Risk factors for subsidence in anterior cervical fusion with stand-alone polyetheretherketone (PEEK) cages: a review of 82 cases and 182 levels

Introduction

To determine risk factors for subsidence in patients treated with anterior cervical discectomy and fusion (ACDF) and stand-alone polyetheretherketone (PEEK) cages.

Materials and methods

Records of patients with degenerative spondylosis or traumatic disc herniation resulting in radiculopathy or myelopathy between C2 and C7 who underwent ACDF with stand-alone PEEK cages were retrospectively reviewed. Cages were filled with autogenous cancellous bone harvested from iliac crest or hydroxyapatite. Subsidence was defined as a decrease of 3 mm or more of anterior or posterior disc height from that measured on the postoperative radiograph. Eighty-two patients (32 males, 50 females; 182 treatment levels) were included in the analysis.

Results

Most patients had 1–2 treatment levels (62.2 %), and 37.8 % had 3–4 treatment levels. Treatment levels were from C2–7. Of the 82 patients, cage subsidence occurred in 31 patients, and at 39 treatment levels. Multivariable analysis showed that subsidence was more likely to occur in patients with more than two treatment levels, and more likely to occur at treatment levels C5–7 than at levels C2–5. Subsidence was not associated with postoperative alignment change but associated with more disc height change (relatively oversized cage).

Conclusion

Subsidence is associated with a greater number of treatment levels, treatment at C5–7 and relatively oversized cage use.     

Transforaminal lumbar interbody fusion (TLIF) versus posterolateral instrumented fusion (PLF) in degenerative lumbar disorders: a randomized clinical trial with 2-year follow-up

Purpose

The aim of the present study was to analyze outcome, with respect to functional disability, pain, fusion rate, and complications of patients treated with transforaminal lumbar interbody fusion (TLIF) in compared to instrumented poserolateral fusion (PLF) alone, in low back pain. Spinal fusion has become a major procedure worldwide. However, conflicting results exist. Theoretical circumferential fusion could improve functional outcome. However, the theoretical advantages lack scientific documentation.

Methods

Prospective randomized clinical study with a 2-year follow-up period. From November 2003 to November 2008 100 patients with severe low back pain and radicular pain were randomly selected for either posterolateral lumbar fusion [titanium TSRH (Medtronic)] or transforaminal lumbar interbody fusion [titanium TSRH (Medtronic)] with anterior intervertebral support by tantalum cage (Implex/Zimmer). The primary outcome scores were obtained using Dallas Pain Questionnaire (DPQ), Oswestry disability Index, SF-36, and low back pain Rating Scale. All measures assessed the endpoints at 2-year follow-up after surgery.

Results

The overall follow-up rate was 94 %. Sex ratio was 40/58. 51 patients had TLIF, 47 PLF. Mean age 49(TLIF)/45(PLF). No statistic difference in outcome between groups could be detected concerning daily activity, work leisure, anxiety/depression or social interest. We found no statistic difference concerning back pain or leg pain. In both the TLIF and the PLF groups the patients had significant improvement in functional outcome, back pain, and leg pain compared to preoperatively. Operation time and blood loss in the TLIF group were significantly higher than in the PLF group (p < 0.001). No statistic difference in fusion rates was detected.

Conclusions

Transforaminal interbody fusion did not improve functional outcome in patients compared to posterolateral fusion. Both groups improved significantly in all categories compared to preoperatively. Operation time and blood loss were significantly higher in the TLIF group.     

Pyogenic lumbar spondylodiscitis treated with transforaminal lumbar interbody fusion: safety and outcomes

Purpose

Our aim was to study the safety and outcomes of posterior instrumentation and transforaminal lumbar interbody fusion (TLIF) for treating pyogenic lumbar spondylodiscitis.

Methods

Retrospective analysis was performed on prospectively collected data of 27 consecutive cases of lumbar pyogenic spondylodiscitis treated with posterior instrumentation and TLIF between January 2009 and December 2012. Cases were analysed for safety, radiological and clinical outcomes of transforaminal interbody fusion using bone graft?±?titanium cages. Interbody metallic cages with bone graft were used in 17 cases and ten cases used only bone graft. Indications for surgical treatment were failed conservative management in 17, neurodeficit in six and significant bony destruction in four.

Results

There were no cases reporting cage migration, loosening, pseudoarthrosis or recurrence of infection at a mean follow-up of 30 months. Clinical outcomes were assessed using Kirkaldy–Willis criteria, which showed 14 excellent, nine good, three fair and one poor result. Mean focal deformity improved with the use of bone graft?±?interbody cages, and the deformity correction was maintained at final follow-up. Mean pre-operative focal lordosis for the graft group was 8.5° (2–16.5°), which improved to 10.9 °(3.3–16°); mean pre-operative focal lordosis in the group treated with cages was 6.7 °(0–15°), which improved to 7°(0–15°) .

Conclusion

TLIFs with cages in patients with pyogenic lumbar spondylodiscitis allows for acceptable clearance of infection, satisfactory deformity correction with low incidence of cage migration, loosening and infection recurrence.

     

Comparative effectiveness of PEEK rods versus titanium alloy rods in lumbar fusion: A preliminary report

Background

Posterior lumbar instruments made of titanium and its alloys could change the physiological distribution of load at the instrumented and adjacent segments, which is a main cause of implant failure, non-fusion and adjacent segment degeneration. Posterior lumbar rods made of polyetheretherketone (PEEK) which is a semirigid alternative to titanium and its alloys have been introduced in lumbar fusion. This prospective study compared the radiological and clinical outcomes of patients undergoing lumbar fusion with PEEK rods versus titanium alloy rods.

Methods

Using transpedicular fixation and lumbar fusion, 21 patients were treated with titanium alloy rods (TI group), and 20 patients with PEEK rods (PEEK group). Radiological and clinical outcomes were evaluated, including the status of the implanted instruments, fusion rate, lumbar lordosis angle (LA), disc space height (DH), visual analog score (VAS) for lower back pain (VAS-BP) and leg pain (VAS-LP), Japanese Orthopedic Association scoring system (JOA score) and complications.

Results

Clinical VAS-BP, VAS-LP and JOA scores were significantly improved at 3 months, 6 months, and 1 year postoperatively as compared with preoperative scores in both groups (p?<?0.05), with similar levels of improvement observed at the same time points postoperatively between the two groups. The overall fusion rate was 100 % at the 1-year follow-up for both groups. No significant differences in lumbar lordosis angle were found preoperatively, 1 week and 1 year postoperatively in both groups (p?>?0.05). The postoperative increase of disc space height and loss of disc space height during the follow-up showed a similar extent of change between both groups (p?>?0.05).

Conclusions

PEEK rods offer a similar radiological and clinical efficacy as titanium alloy rods. PEEK rods, as a semirigid implant with unique characteristics, may be an effective alternative treatment for patients with degenerative lumbar disease in lumbar fusion.     

Expandable titanium cages for anterior column cervical reconstruction and their effect on sagittal profile: a review of 48 cases

Background

Expandable cervical cages have been utilised successfully to reconstruct the cervical spine for various conditions. However, to date there are only limited data on their influence on cervical sagittal profile. In this retrospective study, we present our experience with performing anterior cervical corpectomy in one or two levels using expandable titanium cages in order to achieve stable reconstruction and restoration of cervical lordosis.

Methods

A case series of data from 48 consecutive patients (20 men, 28 women; mean age 61 years) operated upon in a 5-year-period is retrospectively reviewed. Standard anterior single- or two-level cervical corpectomy, fusion and spinal reconstruction were performed, including placement of an expandable titanium cage and an anterior cervical plate. The mean follow-up was 23 months (range, 8–42 months). Outcome was measured by clinical examinations and visual analogue scale (VAS) scale; myelopathy was classified according the Nurick grading system. Radiographic analysis comprised several parameters, including segmental Cobb angle, cervical lordosis, subsidence ratio and sagittal cage angle. Computed tomography was done 1 and 2 years after surgery; cervical spine radiographs were obtained 3, 6, 12 and 24 months after surgery.

Results

In 38 patients (79 %) osseous fusion or stability of construct could be demonstrated in the 2-year follow up examination. The mean restoration of segmental Cobb angle as well as cervical lordosis amounted to 7.6° and 5.4° respectively, both being statistically significant. Furthermore, a profound correction (10° or more) of the sagittal cervical curve was shown in 15 patients.

Conclusion

Regarding the restoration of the physiological sagittal cervical profile, expandable cervical cages seem to be efficient and easy to use for cervical spine reconstruction after anterior corpectomy. Donor-site-related complications are avoided, fast and strong reconstruction of the anterior column is provided, resulting in satisfactory fusion rates after 2 years.     

Evaluation of a polyetheretherketone (PEEK) titanium composite interbody spacer in an ovine lumbar interbody fusion model: biomechanical,microcomputed tomographic,and histologic analyses

Background Context

The most commonly used materials used for interbody cages are titanium metal and polymer polyetheretherketone (PEEK). Both of these materials have demonstrated good biocompatibility. A major disadvantage associated with solid titanium cages is their radiopacity, limiting the postoperative monitoring of spinal fusion via standard imaging modalities. However, PEEK is radiolucent, allowing for a temporal assessment of the fusion mass by clinicians. On the other hand, PEEK is hydrophobic, which can limit bony ingrowth. Although both PEEK and titanium have demonstrated clinical success in obtaining a solid spinal fusion, innovations are being developed to improve fusion rates and to create stronger constructs using hybrid additive manufacturing approaches by incorporating both materials into a single interbody device.

Comparison in the same intervertebral space between titanium-coated and uncoated PEEK cages in lumbar interbody fusion surgery

BackgroundsDisadvantages of polyetheretherketone (PEEK) cages are their smooth and hydrophobic surfaces and their lack of osteoconductivity. Titanium (Ti) coated PEEK cage has been innovated to overcome these potential concerns. However, few well-designed studies have investigated the efficacy of Ti-coated PEEK cage on interbody fusion in humans. This study aimed to evaluate the efficacy of Ti coating on bone ongrowth at bone–implant surface by simultaneously comparing Ti-coated and uncoated PEEK cages in the same intervertebral space.MethodsThis study is a prospective comparative study for the two different cages. Twenty-six subjects who underwent one-level instrumented posterior lumbar interbody fusion (PLIF) were included. Two PEEK cages [a plasma-sprayed Ti-coated (PTC-PEEK) and an uncoated PEEK cage] were inserted in the same intervertebral space. Fusion rates, cage subsidence, and vertebral cancellous condensation (VCC) around the cage, which indicates bone growth on the surface of each cage, were assessed by thin-slice computed tomography (CT) immediately (within 1 week) and at 3 months postoperatively. A functional radiograph was obtained at 3 and 12 months postoperatively.ResultsTwenty-three subjects showed solid fusion at 3 months postoperatively (fusion rate, 88%). Cage subsidence was not observed. VCC was often observed around the PTC-PEEK cage as evaluated by completely synchronized CT images between immediately and at 3 months postoperatively. Quantified VCC around the cage was significantly larger in the PTC-PEEK cage than in the uncoated PEEK cage (P = 0.01).ConclusionsThe Ti-coated PEEK cage exhibits radiographic signs, suggesting bone ongrowth, as represented by VCC around the cage compared with that around the uncoated PEEK cage. The Ti-coated PEEK cage has the potential to promote solid fusion and to improve clinical outcomes in lumbar interbody fusion surgery.     

An analysis of fusion cage migration in unilateral and bilateral fixation with transforaminal lumbar interbody fusion

Purpose

To investigate if instrumentation (unilateral vs. bilateral fixation) has an effect on the rate of fusion cage migration.

Methods

This clinical study of transforaminal lumbar interbody fusion involved a prospective group of 116 patients who were randomly assigned to either unilateral (n = 57) or bilateral (n = 59) fixation. Fourteen were lost to follow-up (11 from the unilateral group and 3 from the bilateral group).

Results

The unilateral fixation group consisted of 20 male and 26 female patients. In the unilateral group, the mean age was 53.5 years (range, 18–77), and the preoperative diagnosis consisted of degenerative disc disease, with or without herniated disc (n = 44), and degenerative spondylolisthesis with spinal stenosis (n = 2). The bilateral fixation group consisted of 20 male and 36 female patients. In the bilateral group, the mean age was 55.7 years (range, 26–82), and the preoperative diagnosis consisted of degenerative disc disease, with or without herniated disc (n = 40), and degenerative spondylolisthesis with spinal stenosis (n = 16). A total of 17 cases of cage migration were found; of these, 11 were from the unilateral group and 6 from the bilateral group, resulting in rates of cage migration of 23 and 11 % (p = 0.03), respectively. In regard to migration cases, 5 were male and 12 were female. Ages ranged from 27 to 79 years (mean age, 55 years).

Conclusion

We conclude that unilateral fixation is not stable enough to prevent fusion cage migration in some patients who undergo TLIF.     

Failure of a polyether-ether-ketone expandable interbody cage following transforaminal lumbar interbody fusion

Purpose

Expandable cages are a more recent option for maintaining or restoring disc height and segmental lordosis with transforaminal lumbar interbody fusion (TLIF). Complications associated with expandable cages have not yet been widely reported. We report a case of postoperative failure of a polyether-ether-ketone (PEEK) expandable interbody device used during TLIF.

Methods

A 50-year-old man presented with severe back and right leg pain after undergoing L4-5 and L5-S1 TLIFs with expandable cages and L3-S1 posterior instrumented fusion. Imaging showed retropulsion of a portion of the interbody cage into the spinal canal causing nerve compression. Displacement occurred in a delayed manner. In addition, pseudoarthrosis was present.

Results

The patient underwent re-exploration with removal of the retropulsed wafer and redo fusion.

Conclusions

Expandable cages are a recent innovation; as such, efficacy and complication data are limited. As with any new device, there exists potential for mechanical failure, as occurred in the case presented.

     

Transforaminal lumbar interbody fusion with one cage and excised local bone

Introduction

The effect of transforaminal lumbar interbody fusion (TLIF) with one cage and excised local bone were investigated in 52 patients with a mean follow-up of 18.2 months.

Method

The clinical outcomes including the modified Prolo scale and a visual analog scale (VAS), and radiological assessments including the ratio of interbody graft area, fusion rate, posterior disk height (PH), and the lordosis angle (LA) of the motion segment were studied.

Results

According to a modified Prolo scale, 90.4% of the patients obtained either excellent or good results. The VAS significantly decreased postoperatively. There was significant postoperative improvement of the PH and LA, and no significant loss of the PH and LA was found at final follow-up. The fusion rate in this series was 96.6%.

Conclusion

In conclusion, TLIF with one cage and excised local bone grafting can provide satisfactory treatment outcomes and solid interbody fusion without harvesting and grafting autologous iliac bone.     

Comparison of stand-alone polyetheretherketone cages and iliac crest autografts for the treatment of cervical degenerative disc diseases

Background

Anterior cervical decompression and fusion (ACDF) is a widely accepted surgical procedure for the treatment of cervical degenerative disc diseases. This retrospective study was designed to analyze and compare the efficacy and outcomes of anterior cervical fusion using stand-alone polyetheretherketone (PEEK) cages and autogenous iliac crest grafts with the anterior cervical plating system.

Methods

A total of 72 consecutive patients suffering from cervical degenerative disc diseases treated with ACDF from June 2005 to Dec 2008 were enrolled in the study. Patients in group A (40 patients, 64 segments) had anterior interbody fusion with stand-alone PEEK cages and patients in group B (32 patients, 51 segments) with autogenous iliac crest graft combined with anterior plate fixation. The operative time and intraoperative blood loss were recorded. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system; cervical lordosis, intervertebral height, and cervical fusion status were assessed on X-ray and computed tomography.

Findings

The mean follow-up period was 17.3 months in the stand-alone cage group and 23.2 months in the autologous iliac crest graft group. The operative time and intraoperative blood loss in group A were much less than those in group B (p?

Conclusions

The stand-alone PEEK cage is a good substitute for fusion in patients with cervical disc disease; it can effectively restore the cervical physiological curvature and the intervertebral height, facilitate radiological follow-up, cause few complications, and leads to satisfactory outcomes.

     

Does partial coating with titanium improve the radiographic fusion rate of empty PEEK cages in cervical spine surgery? A comparative analysis of clinical data

Background

Anterior cervical diskectomy and fusion (ACDF) is a well-established surgical treatment. Several types of intervertebral spacers can be used, but there is increasing evidence that PEEK cages yield insufficient fusion and thus less clinical improvement. The study aim was to assess the outcomes of single-level ACDF with an empty PEEK cage partially coated with titanium.

Methods

This prospective multicenter single-arm clinical study collected follow-up data at 6, 12, and 18 months. A post hoc comparison was made to closely matched patients from another similar trial treated with identically designed, empty, uncoated PEEK cages.

Results

There were 49 of 50 patients (98%) who met the MCID of 3+ points of improvement on VAS pain or had an 18-month VAS?≤?1. Yet even by 18 months post-op, only 40 of 50 (80%) PEEK?+?Ti patients achieved complete bony fusion. The PEEK?+?Ti group (n?=?49) seemed to have somewhat better fusion scores and significantly better pain relief at 6 M than the matched controls (n?=?49), but these differences did not persist at 12 M or 18 M. Patients (with either implant) who achieved complete bony fusion had significantly better improvement of pain at 6 M and disability at 6 M and 12 M than patients that remained unfused.

Conclusions

ACDF is effective treatment for cervical myelopathy and radiculopathy. Although this and other studies show that titanium fuses better, partial coating of a PEEK cage does not improve the fusion rate sufficiently or confer other lasting clinical benefit. PEEK cages fully coated with titanium should be tested in prospective randomized comparative trials.

Trial registration

Prospective, multicenter, single-arm clinical observational study without an individual Trial registration number. Study design and post hoc data analysis according to the “PIERCE-PEEK study”, ISRCTN42774128, retrospectively registered 14 April 2009.

     

A comparative study between local bone graft with a cage and with no cage in single posterior lumbar interbody fusion (PLIF): a multicenter study

Objective

A retrospective study was performed to compare the clinical and radiological results between local bone graft with a cage and without using a cage in patients treated with posterior lumbar interbody fusion surgery.

Methods

A total of 115 consecutive patients who underwent PLIF in three institutions were evaluated from December 2005 to December 2010. 53 patients received PLIF with local bone graft combined with using one PEEK cage, and 62 patients received the PLIF with local bone graft without using a cage. The clinical data and perioperative complications of the patients in the two groups were recorded. Preoperative and postoperative radiographs were taken to calculate the disc height and the interbody bony fusion rate. Functional outcome was assessed using the Kirkaldy-Willis criteria at the follow-up time. The results between the cage group and no cage group were compared.

Results

The mean follow-up time was 19 months in no cage group and 18.5 months in cage group (P = 0.716). 20.9 % of patients (13 cases) in no cage group and 20.7 % of patients (11 cases) in cage group developed surgical complications perioperatively (P = 0.978). 51.6 % patients in no cage group got excellent functional outcome at the final follow-up while 54.7 % patients in cage group (P = 0.944). The mean interbody bony fusion time was 7.5 ± 4.5 months in no cage group and 8 ± 3.5 months in cage group (P = 0.841). According to the radiographs measurement, no significant difference was found for the disc height at each level between the two groups at the final follow-up.

Conclusion

Local bone graft without a cage is as beneficial as that with a cage for PLIF. Comparing with local bone graft using a single cage, we believe that the purely local bone graft is a more ideal way in single PLIF.     

Bony ingrowth potential of 3D-printed porous titanium alloy: a direct comparison of interbody cage materials in an in vivo ovine lumbar fusion model

Background Context

There is significant variability in the materials commonly used for interbody cages in spine surgery. It is theorized that three-dimensional (3D)-printed interbody cages using porous titanium material can provide more consistent bone ingrowth and biological fixation.

Bone union rate with recombinant human bone morphogenic protein-2 versus autologous iliac bone in PEEK cages for anterior lumbar interbody fusion

Purpose

Autologous iliac crest bone graft (ICBG) is the gold standard material for spinal fusion. Bone graft substitutes, such as recombinant human bone morphogenic protein 2 (rhBMP-2) have been developed to promote spinal fusion and address morbidity issues related to ICBG harvesting. The objective of this study was to compare bone fusion rates after anterior lumbar interbody fusion (ALIF) between ICBG and rhBMP-2 by examining thin-cut computed tomography (CT) images at the one year follow-up.

Methods

Fifty one patients (62 levels) who underwent single- or two-level ALIF via the video-assisted minimally invasive anterior approach in our institution were assessed. Radiolucent cages were inserted in all cases. Each cage has a middle beam delimiting two chambers. Grafting was performed as follows: one chamber was filled with autologous ICBG, and the other chamber was filled with 6 mg of rhBMP-2. Thin-cut CT-scan multiplanar reconstruction analyses were performed to assess the rate and quality of bone fusion at one year of follow-up.

Results

Fusion was observed in 55 levels (88.7 %), with significant differences in fusion rates with rhBMP-2 and ICBG (71 % vs. 88.7 %) (P=0.001). Osteogenesis in the rhBMP-2 chamber had a centripetal pattern in all cases, leaving a central void in 97.7 % of cases representing 38.3 % of the surface of its chamber (range 0–80.3 %). In ICBG chambers, graft resorption was present in 44.4 %, representing 9.8 % of the chamber surface (range 0–52.2 %).

Conclusion

RhBMP-2 was inferior to ICBG in terms of rate and quality of bone fusion in one- or two-level ALIF.     

Influence of transforaminal lumbar interbody fusion procedures on spinal and pelvic parameters of sagittal balance

Introduction

Restitution of sagittal balance is important after lumbar fusion, because it improves fusion rate and may reduce the rate of adjacent segment disease. The purpose of the present study was to describe the impact of transforaminal lumbar interbody fusion (TLIF) procedures on pelvic and spinal parameters and sagittal balance.

Materials and methods

Forty-five patients who had single-level TLIF were included in this study. Pelvic and spinal radiological parameters of sagittal balance were measured preoperatively, postoperatively and at latest follow-up.

Results

Age at surgery averaged 58.4 (±9.6) years. Mean follow-up was 35.1 months (±4.1). Twenty-nine percent of the patients exhibited anterior imbalance preoperatively, with high pelvic tilt (17.6° ± 7.9°). Of the 32 (71%) patients well balanced before the procedure, 22 (70%) had a large pelvic tilt (>20°), due to retroversion of the pelvis as an adaptive response to the loss of lordosis. Three dural tears (7%) were reported intraoperatively. Interbody cages were more posterior than intended in 27% of the cases. Disc height and lumbar lordosis at fusion level significantly increased postoperatively (p < 0.05 and p < 0.001). Pelvic tilt was significantly reduced (p < 0.01) postoperatively, whereas the global sagittal balance was not significantly modified (p = 0.07).

Conclusion

Single-level circumferential fusion helps patients reducing their pelvic compensation, but the amount of correction does not allow for complete correction of sagittal imbalance.     

A minimum 2-year comparative study of autologous cancellous bone grafting versus beta-tricalcium phosphate in anterior cervical discectomy and fusion using a rectangular titanium stand-alone cage

Although titanium stand-alone cages are commonly used in anterior cervical discectomy and fusion (ACDF), there are several concerns such as cage subsidence after surgery. The efficacy of β-tricalcium phosphate (β-TCP) granules as a packing material in 1- or 2-level ACDF using a rectangular titanium stand-alone cage is not fully understood. The purpose of this study is to investigate the validity of rectangular titanium stand-alone cages in 1- and 2-level ACDF with β-TCP. This retrospective study included 55 consecutive patients who underwent ACDF with autologous iliac cancellous bone grafting and 45 consecutive patients with β-TCP grafting. All patients completed at least 2-year postoperative follow-up. Univariate and multivariate analyses were performed to examine the associations between study variables and nonunion after surgery. Significant neurological recovery after surgery was obtained in both groups. Cage subsidence was noted in 14 of 72 cages (19.4 %) in the autograft group and 12 of 64 cages (18.8 %) in the β-TCP group. A total of 66 cages (91.7 %) in the autograft group showed osseous or partial union, and 58 cages (90.6 %) in the β-TCP group showed osseous or partial union by 2 years after surgery. There were no significant differences in cage subsidence and the bony fusion rate between the two groups. Multivariate analysis using a logistic regression model showed that fusion level at C6/7, 2-level fusion, and cage subsidence of grades 2–3 were significantly associated with nonunion at 2 years after surgery. Although an acceptable surgical outcome with negligible complication appears to justify the use of rectangular titanium stand-alone cages in 1- and 2-level ACDF with β-TCP, cage subsidence after surgery needs to be avoided to achieve acceptable bony fusion at the fused segments. Fusion level at C6/7 or 2-level fusion may be another risk factor of nonunion.