Fusion criteria for posterior lumbar interbody fusion with intervertebral cages : the significance of traction spur

Comparison of mMO-TLIF via Midline Incision Versus MIS-TLIF via Wiltse Approach in Lumbar Degenerative Disease

Background

To compare the clinical and radiological outcomes of modified mini-open transforaminal lumbar interbody fusion (mMO-TLIF) via posterior midline incision for "targeted limited dissection" versus minimal invasive transforaminal lumbar interbody fusion (MIS-TLIF) via Wiltse approach in lumbar degenerative diseases.

Methods

A total of 60 consecutive patients in our center from January 2019 to March 2020 were enrolled, including 30 patients who were treated with mMO-TLIF via posterior midline incision and 30 treated with MIS-TLIF through the Wiltse approach. Perioperative parameters were recorded. The questionnaires of Oswestry Disability Index (ODI) and Visual Analogue Score (VAS) were conducted before the operation and after the operation (3 days, 1 week, and 2 years). CT and MRI radiological outcomes were evaluated before the operation and at a 2-year follow-up.

Results

There were no significant differences in the general data, gender, age, and BMI between the two groups. All patients were successfully operated without intraoperative complications. There were significant differences between the two groups in the operation time (p < 0.001) and intraoperative bleeding (p < 0.05). There was no difference in ODI and VAS scores between groups pre- and post-operatively, but they were both significantly improved compared to those before the operation (p < 0.01). At a 2-year follow-up, the paraspinal muscle atrophy and fat infiltration were increased comparing to pre-operation, but the difference was also not statistically significant (p > 0.05). In addition, both the two groups' fusion rates were more than 90% at a 2-year follow-up, however, no difference was detected between the two groups.

Conclusion

mMO-TLIF via midline incision for "targeted limited dissection" could achieve similar clinical and radiological outcomes as MIS-TLIF for lumbar degenerative disease.

Traction Spurs in the Lumbar Spine: A Historical Overview and Future Perspectives

Numerous studies have explored the connection between lumbar osteophytes, their pathophysiology, and instability since Macnab's 1971 report on traction spurs as an indicator of lumbar instability. This study provides a narrative historical overview of traction spurs, a classic finding that suggests lumbar instability. It summarizes the causes of anterior lumbar vertebral osteophytes, the relationship between traction spurs and lumbar spinal instability, and the clinical significance of traction spurs. Vertebral osteophytes are grouped into two categories, namely, traction spurs or claw spurs, which represent different stages of the same pathological process. Traction spurs are indicative of instability and occur in the early stage of disc degeneration, characterized by temporary dysfunction or instability. Traction spur formation following fusion surgery can predict union or nonunion, and it serves as an indicator of preoperative and postoperative segmental instability. The relationship between traction spurs and radiographic instability, as well as their association with imaging findings such as CT and MRI, has been clarified. Additionally, finite element analysis and mechanical testing have been used to investigate the significance of traction spurs. However, further research is needed to verify that traction spurs are an accurate indicator of pre- and postoperative lumbar instability.

Incidence and Predictive Factors of New Onset Postoperative Sacroiliac Joint Pain After Posterior Lumbar Fusion Surgery for Degenerative Lumbar Disease

Introduction

To explore the incidence and predictive factors of new onset postoperative sacroiliac joint pain (PSJP) after posterior lumbar fusion surgery for degenerative lumbar disease.

Methods

Three hundred and sixty-seven patient medical records from January 2020 to December 2021 were retrieved. The patients were divided into two groups: PSJP group and N-PSJP (non-postoperative sacroiliac joint pain group). To investigate potential risk factors for PSJP, HU value (Hounsfield unit value) was assessed on CT scans. ImageJ software was used to assess the fat and muscle of the lumbar multifidus muscle (LMM) in the axial MRI image, the red area was marked as fat and the rest were muscles to calculate the ratio of fatty infiltration. Patient characteristics, surgical variables and radiographic parameters were analyzed statistically.

Results

Twenty of 367 patients were diagnosed with PJSP at postoperative follow-up. Patients with PSJP presented with significantly higher HU value. For surgical variables, PSJP patients received more operations including distal fusion level at sacrum than the N-PSJP group. For radiographic parameters, most of the patients in the PSJP group had more severe fatty atrophic muscle in the LMM compared to the N-PSJP group. There was no statistically significant difference between the two groups in preoperative and postoperative lumbar lordosis (LL), angle of lumbar lordosis of fixed lumbar vertebrae (FV-LL), pelvic incidence (PI), sacrum slope (SS). The bivariate logistic regression model revealed preoperative fat infiltration rate of the LMM, and higher HU value were independently associated with PSJP.

Conclusion

PSJP for degenerative lumbar disease was 5.4%, the predictive factors included preoperative severe infiltration of LMM, distal fusion level at sacrum and higher HU value.

The Significance of Extra-Cage Bridging Bone via Radiographic Lumbar Interbody Fusion Criterion

STUDY DESIGN

Prospective observational study.

OBJECTIVES

We aimed to analysis the distributional patterns of the intra- and extra-cage bridging bone (InCBB and ExCBB) and the significance of ExCBB using suggested lumbar interbody fusion criterion.

METHODS

This study included the patients with planned single-level transforaminal lumbar interbody fusion. We divided bridging bone into InCBB (in void of right or left cage) and ExCBB (outside of cages; anterior, posterior, intermediate, right, or left) and graded bridging scores from 0 to 2 on postoperative 1-year computed tomography. The fusion was defined as at least having one or more graded 2 and the evaluation were conducted twice by 2 raters.

RESULTS

Sixty-five patients were enrolled. All values of intra- and inter-rater reliability in left InCBB, anterior, and posterior ExCBB showed good agreements (≥0.75). Both InCBBs showed similar mean bridging scores (Rt:1.43 vs Lt:1.48), and in ExCBBs, the anterior was the highest (1.43), followed by the posterior (1.14); the right and left were the lowest (0.49 and 0.52 respectively). In subjects determined as fusion (85.4%), complete bridging was observed more in ExCBB (88.8%) than in InCBB (69.9%).

CONCLUSIONS

Given the higher bridging scores in both InCBBs and Ant. ExCBB, bone grafting is important promoting factor to increase the interbody bridging bone regardless of outside or in void of cages. Based on our suggested criterion, ExCBB has a greater proportion compared to InCBBs for determining the fusion and extra-cage bone grafting should be considered as important procedures for interbody fusion.

Long-Term Outcome After Midline Lumbar Fusion for the Treatment of Lumbar Spine Instability Due to Degenerative Disease

BACKGROUND

Midline lumbar fusion (MIDLF) is one promising new surgical technique that has been developed to minimize perioperative damage to the paravertebral stabilizing musculotendinous system. The aim of this study was to assess long-term clinical and radiological effects of MIDLF.

METHODS

This prospective cohort study evaluated patients who underwent MIDLF for degenerative spinal instability. Clinical and radiological examinations were performed before and after surgery. Perioperative and postoperative complications were recorded. Follow-up was 2 years. P ≤ 0.05 was considered statistically significant.

RESULTS

The study included 64 patients (mean age 58.9 ± 10.7 years; 41 women [64.1%]). The most frequent indication for MIDLF was degenerative spondylolisthesis grade I (28 cases [43.8%]); the prevalent spinal segment to be fused was L4-L5 (35 cases [54.7%]). Mean duration of surgery was 148.2 ± 28.9 minutes. Relief of low back pain and leg pain was significant and stable in the postoperative period as assessed by visual analog scale (P < 0.001). Of patients, 86.9% reported fair, good, or excellent outcomes in terms of pain relief based on MacNab score 2 years after surgery. Patients' level of function in activities of daily living improved significantly based on Oswestry Disability Index score: from 66.8 ± 9.8 before surgery to 33.9 ± 16.5 2 years after surgery (P < 0.001). X-rays and computed tomography at 12 months showed interbody fusion in 46 cases (73.4%), inconclusive results in 13 cases (20.3%), and no fusion in 4 cases (6.3%). No damage to neural or vascular structures and no failure of hardware or screw loosening were recorded.

CONCLUSIONS

MIDLF is a safe, efficient method for surgical treatment of lumbar spine instability. Its limited invasiveness contributes to better preservation of paravertebral muscles and enhanced postoperative spinal stability.

Augmenting posterolateral fusion with transforaminal lumbar interbody fusion cage improves clinical outcome, but not fusion rate, of posterior decompression

Objective

This study was performed to compare fusion rates and clinical outcomes of posterior decompression by posterolateral fusion (PLF) versus transforaminal lumbar interbody fusion (TLIF) for treatment of lumbar spinal stenosis.

Methods

This retrospective cohort study involved 157 patients with lumbar spinal stenosis treated with instrumented PLF alone or instrumented PLF combined with TLIF from 2010 to 2018. The patients were divided into two groups: the PLF group (Group A), in which posterior decompression with instrumented PLF was performed, and the cage-augmented group (Group B), in which TLIF was added to the procedures described for the PLF group. Patient outcomes (Oswestry Disability Index, visual analog scale score, and 36-Item Short-Form Health Survey scores) and fusion rates were compared.

Results

The fusion rate was similar between the two groups. Among patients with two- and three-level fusion, improvements in the clinical outcome scores were significantly greater in Group B than Group A.

Conclusion

Combining TLIF with PLF provides better clinical outcomes than PLF alone when multilevel fusion is indicated. TLIF augmentation does not improve the fusion rates in either single- or multi-level surgery.

Application of a novel porous tantalum implant in rabbit anterior lumbar spine fusion model: in vitro and in vivo experiments

BACKGROUND

Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility.

METHODS

Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test.

RESULTS

All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs. 2.83 ± 0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs. 1.23 ± 0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces.

CONCLUSION

This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.

Comparison of unilateral pedicle screw fixation and interbody fusion with PEEK cage vs. standalone expandable fusion cage for the treatment of unilateral lumbar disc herniation

INTRODUCTION

This study was conducted to compare the clinical effects of unilateral pedicle screw fixation and interbody fusion with PEEK cage (UPSFC) and standalone expandable fusion cage (SAEFC) on unilateral lumbar disc herniation.

MATERIAL AND METHODS

From September 2011 to July 2014, a respective investigation was performed on 130 lumbar disc herniation patients treated with SAEFC or UPSFC. The hospital stay, operating time, blood loss, Japanese orthopaedic association scores (JOA), and visual analogue score (VAS) in the two groups were compared using Student's t-test.

RESULTS

The average of follow-up time was 25.6 ±6.4 and 25.2 ±5.8 months, respectively. No significant difference in the postoperative hospitalizsation, intraoperative blood loss, operative time, and postoperative fusion rate was detected between the two groups. VAS score in the UPSFC group was significantly lower than in the SAEFC group at 6 and 12 months after operation (p = 0.014, p = 0.004). X-ray images indicated that the subsidence rate was 8.1% (5/62) in the SAEFC group, while no subsidence was detected in UPSFC group 12 month after operation.

CONCLUSIONS

Both SAEFC and UPSFC are effective techniques. UPSFC may be a better choice for patients with lumbar disc herniation and unilateral limb symptoms of nerve root in view of the advantages of better low back pain relief and low subsidence rate.

Approach to interpret images produced by new generations of multidetector CT scanners in post-operative spine

OBJECTIVE

To reach a practical approach to interpret MDCT findings in post-operative spine cases and to change the false belief of CT failure in the setting of instruments secondary to related artefacts.

METHODS

We performed observational retrospective analysis of premier, early and late MDCT scans in 68 post-operative spine patients, with emphasis on instruments related complications and osseous fusion status. We used a grading system for assessment of osseous fusion in 35 patients and we further analysed the findings in failure of fusion, grade (D).

RESULTS

We observed a variety of instruments related complications (mostly screws medially penetrating the pedicle) and osseous fusion status in late scans. We graded 11 interbody and 14 posterolateral levels as osseous fusion failure, showing additional instruments related complications, end plates erosive changes, adjacent segments spondylosis and malalignment.

CONCLUSION

Modern MDCT scanners provide high quality images and are strongly recommended in assessment of the instruments and status of osseous fusion. In post-operative imaging of the spine, it is essential to be aware for what you are looking for, in relevance to the date of surgery. Advances in knowledge: Modern MDCT scanners allow assessment of instruments position and integrity and osseous fusion status in post-operative spine. We propose a helpful algorithm to simplify interpreting post-operative spine imaging.

Influence of smoking on spinal fusion after spondylodesis surgery: A comparative clinical study

BACKGROUND

Smoking is a risk factor in the process of bone healing after lumbar spondylodesis, often associated with complications that occur intraoperatively or during follow-up periods.

OBJECTIVE

To assess if smokers yield worse results concerning lumbar interbody fusion than non-smokers in a clinical comparative setting.

METHODS

Spondylodesis outcomes in 50 patients, 34 non-smokers (mean 58 years; (range 29-81) and 16 smokers (mean 47 years; range 29-75) were compared preoperatively and one year after spondylodesis surgery using Oswestry-Disability-Index (ODI), visual analogue scale (VAS) and radiological outcome analysis of fusion-success.

RESULTS

Smokers showed a comparable ODI-improvement (p = 0.9343) and pain reduction to non-smokers (p = 0.5451). The intake of opioids was only reduced in non-smokers one year after surgery. Fusion success was significantly better in non-smokers (p = 0.01).

CONCLUSIONS

The results indicate that smoking adversely effects spinal fusion. Particularly re-operations caused by pseudarthrosis occur at a higher rate in smokers than in non-smokers.

Incidence and risk factors of persistent low back pain following posterior decompression and instrumented fusion for lumbar disk herniation

INTRODUCTION

The aim of this study was to explore the incidence and risk factors of persistent low back pain (PLBP) following posterior decompression and instrumented fusion for lumbar disk herniation and to provide references in decision-making and surgical planning for both spinal surgeons and surgically treated patients.

PATIENTS AND METHODS

By retrieving the medical records from January 2013 to December 2016, 221 patients were retrospectively reviewed. Patients were classified as having PLBP if numeric rating scale (NRS) scores were >50 at all postoperative follow-up time points (3 months, 6 months, and 12 months). According to the occurrence of PLBP, patients were divided into two groups: PLBP group and non (N)-PLBP group. To investigate risk values for PLBP, the following three categorized factors were analyzed statistically. Patient characteristics: age, gender, body mass index (BMI), preoperative low back pain, comorbidity, smoking, and drinking. Surgical variables: surgical strategy, surgical segment, the number of fusion levels, surgery time, blood loss, and size of incision. Radiographic parameters: preoperative lumbar lordosis (LL), correction of LL at immediate postoperation, Modic changes, and preoperative paraspinal muscle degeneration.

RESULTS

PLBP was detected in 16 patients and were enrolled into the PLBP group. There was no difference between the two groups in age, gender, BMI, comorbidity, smoking, and drinking. The preoperative low back pain was more severe in the PLBP group than that in the N-PLBP group. There was no difference in surgery time, blood loss, surgical strategy, number of fusion levels, and the size of incision. Surgery segment at L₅-S₁ was more prevalent in the PLBP group than that in the N-PLBP group, and there was no difference in preoperative LL, correction of LL, preoperative lumbar mobility, and Modic changes. The fatty infiltration rate (FIR) was larger in the PLBP group than that in the N-PLBP group. Multivariate logistic regression model revealed that preoperative low back pain (NRS > 35), surgery segment at L₅-S₁, and FIR > 15% were independently associated with PLBP.

CONCLUSION

The incidence of PLBP following posterior decompression and instrumented fusion for lumbar disk herniation is 7.2%, and the risk factors include preoperative low back pain, surgery segment at L₅-S₁, and preoperative paraspinal muscle degeneration.

Long-Term Outcomes of Posterior Lumbar Interbody Fusion Using Stand-Alone Ray Threaded Cage for Degenerative Disk Disease: A 20-Year Follow-Up

Study Design

Retrospective study.

Purpose

To analyze outcomes of posterior lumbar interbody fusion (PLIF) stand-alone cages.

Overview of Literature

PLIF for degenerative disk disease using stand-alone cages has lost its popularity owing to implant-related complications and pseudoarthrosis.

Methods

We analyzed the records of 45 patients (18 women, 27 men), operated between January 1994 and December 1996, with a mean follow-up of 18 years 3 months (20 years 3 months–22 years 3 months). Clinical outcomes were measured using visual analogue score (VAS), Oswestry disability index (ODI), Odom's criteria, and radiological measurements of fusion rate, Cobb angle, and implant-related complications conducted at the preoperative evaluation, hospital discharge, 12-month follow-up, and final follow-up.

Results

Preoperative mean VAS (back) was 6.9 and VAS (radicular) was 7.2, with mean improvements (p <0.05) of 2.9 and 3.1, respectively, at the final follow-up. Median preoperative ODI was 64.5, with a mean improvement to 34 and 42 at the 12-month and final follow-ups, respectively (p <0.05). Odom's criteria at the 12-month follow-up were excellent in 11.2% patients, good in 57.7%, fair in 31.1%, and poor in none of the patients; at the final follow-up, no patient was classified as excellent, 71.1% as good, 22.2% as fair, and 6.7% as poor (p <0.05). Pseudoarthrosis was observed in five patients (11.1%), of whom, three (6.6%) required re-operation. Preoperative disk height was 9.23 mm, which increased to 13.33 mm in the immediate postoperative evaluation and was maintained at 10.0 mm at the final follow-up (p <0.05). The preoperative mean L1–S1 Cobb angle was 34.7°, which changed to 44.7° in the immediate postoperative evaluation and dropped to 39.7° at the final follow-up (p <0.005).

Conclusions

PLIF stand-alone cages were associated with good clinical outcomes. Although the fusion rate was excellent, maintenance of disk heights and a lordotic alignment were not achieved in the long term.

Fate of osteophytes and sclerosis in fused segments after lumbar fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the fate of sclerosis and anterior osteophytes in the fused segments after instrumented lumbar fusion for degenerative lumbar disorders.

SUMMARY OF BACKGROUND DATA

Sclerosis and osteophytosis are well-known radiographical findings, but little is known of their significance with regard to spontaneous resorption after spine fusion.

METHODS

Thirty patients (9 males, 21 females; 60 vertebra; mean age of 66.9 yr [45-86 yr]) were divided into a posterolateral fusion group (n = 14, 28 vertebrae) and a posterior lumbar interbody fusion group (n = 16, 32 vertebrae). Using serial radiographs obtained preoperatively; postoperatively at 3, 6, 12, and 24 months; and last follow-up, sclerotic areas of each involved vertebra were mapped and osteophyte lengths were measured.

RESULTS

Sclerosis and osteophytes decreased with time for the instrumented fusion. The decrease in sclerotic areas and osteophytes length was observed as early as 3 months postoperatively, and the significant changes between each time point were noted in initial 3- and 6-month intervals. In terms of the type of surgery, similar changes were noted in the posterolateral fusion and posterior lumbar interbody fusion groups.

CONCLUSION

Resorption of osteophytes and sclerosis after instrumented spine fusion were observed. Significant resorption was noted at 3 and 6 months postoperatively. As well, most graft bone would be incorporated in postoperative 6 months. Resorption of osteophytes and sclerosis after instrumented spine fusion could be helpful to confirm the successful union.

LEVEL OF EVIDENCE

4.

An analysis of heterotopic ossification in cervical disc arthroplasty: a novel morphologic classification of an ossified mass

BACKGROUND CONTEXT

Although the precise cause of heterotopic ossification (HO) remains unclear, it is certain that it increases with time. The reason why the reported occurrence rate has been given as a wider range is that there were no clinical reports that have addressed the occurrence rate based on the morphology and position.

PURPOSE

The aim of this retrospective study was to determine whether radiological parameters had an influence on the formation of HO and to compare the results after cervical arthroplasty using Bryan (Medtronic Sofamor Danek, Memphis, TN, USA), PCM (Cervitech, Rockaway, NJ, USA), and Prestige LP (Medtronic Sofamor Danek) implants.

STUDY DESIGN/SETTING

A retrospective study.

PATIENT SAMPLE

Eighty-one patients were included.

OUTCOME MEASUREMENT

The occurrence of HO was determined at the four corners of the disc space according to the McAfee classification system. Heterotopic ossifications were classified into Type 1, Type 2, and Type 3 HOs (end plate, traction spur, and teardrop types) based on their morphologic features. The presence of preoperative ossifications, sex, type of device, operated level, hybrid implantation, depth behind the prosthesis, cervical lordotic angle, and segmental angle between the footplates of the prosthesis were assessed as predictors in terms of location and morphologic features.

METHODS

Eighty-one patients after 95 cervical arthroplasties using the Bryan (35 segments), PCM (30 segments), and Prestige LP implants (30 segments) underwent postoperative radiographs or three-dimensional computed tomography with a mean follow-up period of 46, 39, and 30 months, respectively, after the operation.

RESULTS

The overall incidence of all cases and one-level subgroup were 64.2% and 60.3%, respectively. According to the types of device, the incidence of HO was 49% (Bryan), 80% (PCM), and 60% (Prestige). Type 1 HO (62.1%) was found only in the posterosuperior disc space. Type 2 HO (13.7%) was primarily detected in the anterosuperior disc space rather than the posterosuperior disc space (3.2%). Type 3 HO (4.2%) developed only in the anterior disc space. In the anterior disc space, the incidence of Type 2 and Type 3 HOs was highest in the PCM group. In the posterior disc space, the Bryan group showed a lower proportion in the high McAfee class than the other device groups. The occurrence of Type 1 HO in the posterosuperior disc space was significantly related with the presence of preoperative ossification (p=.030), ossification in the ligamentum nuchae (p=.027), male sex (p=.042), and PCM device (p=.012). A well-fitting (p<.002) and less lordotic segmental angle (p<.015) were correlated with Type 1 HO. Implantation in the upper cervical level (p=.016) and hybrid implantation with cage (p=.033) or artificial disc (p=.048) on the upper adjacent level were significant risk factors for anterior Type 2 HO. Cervical lordotic angle at 1 month after surgery had a significant connection with the occurrence of anterior Type 2 HO in both groups of all cases (p=.032) and one-level subgroup (p=.000).

CONCLUSIONS

Type 1 HO developed mostly in the posterior disc space. Type 2 HO was the dominant type in the anterior disc space. Type 3 HO developed only in the anterior disc space. It is certain that both Type 1 and Type 2 HOs are related to biomechanical stresses (compressive force for Type 1 HO and traction force for Type 2 HO). It is suggested that a cervical arthroplasty should be selected in terms of the implant level, hybrid conditions on the upper adjacent segment, disc design vulnerable to the pseudotranslation, the presence of preoperative ossification, and fitting implants to end plates to reduce the development of HO.

Minimally invasive multi-level posterior lumbar interbody fusion using a percutaneously inserted spinal fixation system : technical tips, surgical outcomes

OBJECTIVE

There are technical limitations of multi-level posterior pedicle screw fixation performed by the percutaneous technique. The purpose of this study was to describe the surgical technique and outcome of minimally invasive multi-level posterior lumbar interbody fusion (PLIF) and to determine its efficacy.

METHODS

Forty-two patients who underwent mini-open PLIF using the percutaneous screw fixation system were studied. The mean age of the patients was 59.1 (range, 23 to 78 years). Two levels were involved in 32 cases and three levels in 10 cases. The clinical outcome was assessed using the visual analog scale (VAS) and Low Back Outcome Score (LBOS). Achievement of radiological fusion, intra-operative blood loss, the midline surgical scar and procedure related complications were also analyzed.

RESULTS

The mean follow-up period was 25.3 months. The mean LBOS prior to surgery was 34.5, which was improved to 49.1 at the final follow up. The mean pain score (VAS) prior to surgery was 7.5 and it was decreased to 2.9 at the last follow up. The mean estimated blood loss was 238 mL (140-350) for the two level procedures and 387 mL (278-458) for three levels. The midline surgical scar was 6.27 cm for two levels and 8.25 cm for three level procedures. Complications included two cases of asymptomatic medial penetration of the pedicle border. However, there were no signs of neurological deterioration or fusion failure.

CONCLUSION

Multi-level, minimally invasive PLIF can be performed effectively using the percutaneous transpedicular screw fixation system. It can be an alternative to the traditional open procedures.

Long-term clinical and radiological outcomes following stand-alone PLIF surgery using expandable cylindrical threaded cages in patients with degenerative lumbar spine disease

PURPOSE

Although posterior lumbar interbody fusion (PLIF) using stand-alone cages was a popular arthrodesis method, the effectiveness of using such cages has been questioned. We assessed retrospectively the long-term clinical and radiological outcomes of PLIF surgery using stand-alone cages for the treatment of degenerative lumbar spine disease, the incidences of pseudoarthrosis, and its risk factors.

METHODS

Between May 2000 and May 2005, we performed surgery on 211 patients with degenerative lumbar disease. Among those patients, 180 were clinically and radiologically followed for more than 60 months. All 180 patients underwent postoperative follow-up X-rays, including a dynamic view after 3, 6, 12, 24, and 60 months, and computed tomography (CT) after 24 months. The clinical outcomes were analyzed using the mean numeric rating scale (NRS), Oswestry Disability Index (ODI), and Odom's criteria. The factors affecting the clinical success and non-fusion were also analyzed.

RESULTS

The mean NRS scores for the back and leg were 7.1 and 6.9 preoperatively, and 3.0 and 2.7 at 60 months postoperatively, respectively. The ODI decreased from 29.5 preoperatively to 14.1 at 60 months postoperatively. The clinical success rate was only 74.4% in the Odom's criteria, and the significant factor affecting the clinical success was radiological fusion. The radiological fusion assessment at 24 months postoperatively indicated success at 167 levels (85.2%) and failure at 29 levels (14.8%). Disc height changed from 10.25 mm preoperatively to 15.02 mm immediately postoperatively, and gradually decreased to 12.28 mm for 60 months after surgery. The gradual decrease was statistically significant (p < 0.001). The segmental angle changed from 13.59° preoperatively to 12.85° immediately postoperatively, and to 12.76° 60 months after surgery. There was no statistically significant change of the segmental angle during any time (p > 0.05).

CONCLUSION

The use of PLIF with stand-alone threaded cages in degenerative lumbar disease patients resulted in a long-term clinical success rate of 74.4%. Although the radiological fusion rate was 85.2%, continuous reduction of disc height and poor alignment preservation were observed. We conclude, therefore, that PLIF using only stand-alone cages is a poor surgical option for achieving good alignment and disc height restoration in patients with degenerative lumbar disease.