Patient outcomes after decompression and instrumented posterior spinal fusion for degenerative spondylolisthesis

Kinematic Characteristics and Biomechanical Changes of Lower Lumbar Facet Joints Under Different Loads

Objective

To explore the kinematic biomechanical changes and symmetry in the left and right sides of the facet joints of lumbar spine segments under different functional loads.

Methods

Participants (n = 10) performing standing flexion and extension movements were scanned using computed tomography (CT) and dual fluoroscopy imagine system. Instantaneous images of the L₃–S₁ vertebrae were captured, and by matching a three‐dimensional CT model with contours from dual fluoroscopy images, in vivo facet joint movements were reproduced and analyzed. Translations and rotations of lumbar vertebral (L₃ and L₄) facet joints of data were compared for different loads (0, 5, 10 kg). The participants performed flexion and extension movements in different weight‐bearing states, the translations and angles changes were calculated respectively.

Results

From standing to extension, there were no statistical differences in rotation angles for the facet joint processes of different vertebral segment levels under different weight loads (P > 0.05). Mediolateral axis and cranio‐caudal translations under different weight loads were not statistically different for vertebral segment levels (P > 0.05). Anteroposterior translations for L₃ (1.4 ± 0.1 mm) were greater than those for L₄ (1.0 ± 0.1 mm) under the different load conditions (P = 0.04). Bilaterally, mediolateral, anteroposterior, and cranio‐caudal translations of the facet joints under different weights (0, 10 kg) for each segment level (L₃ and L₄) were symmetric (P > 0.05). From flexion to standing, there were no statistical differences in rotation angles for different weights (0, 5, 10 kg) for each level (L₃ and L₄) (P > 0.05). There were no statistical differences between mediolateral, anteroposterior, and cranio‐caudal translations at each segment level (L₃ and L₄) under different loads (P > 0.05). Under the condition of no weight (0 kg), L₃ mediolateral translations on the left side (1.7 ± 1.6 mm) were significantly greater (P = 0.03) than those on the right side (1.6 ± 1.6 mm). Left side (1.0 ± 0.7 mm) L₄ mediolateral translations were significantly smaller (P = 0.03) than those on the right side (1.1 ± 0.7 mm). There were no statistical differences between different weights for either anteroposterior and cranio‐caudal translations (P > 0.05). There were no statistical differences for mediolateral, anteroposterior, and cranio‐caudal translations for 10 kg (P > 0.05).

Conclusion

Lumbar spine facet joint kinematics did not change significantly with increased loads. Anteroposterior translations for L₃ were greater than those for L₄ of the vertebral segments are related to the coronal facet joint surface. Changes in facet surface symmetry indicates that the biomechanical pattern between facet joints may change.

Determination of dynamic instability in lumbar spondylolisthesis using flexion and extension standing radiographs versus neutral standing radiograph and supine MRI

OBJECTIVE

In this study the authors sought to compare the proportion of patients with lumbar spondylolisthesis detected to have dynamic instability based on flexion and extension standing radiographs versus neutral standing radiograph and supine MRI.

METHODS

This was a single-center retrospective study of all consecutive adult patients diagnosed with spondylolisthesis from January 1, 2013, to July 31, 2018, for whom the required imaging was available for analysis. Two independent observers measured the amount of translation, in millimeters, on supine MRI and flexion, extension, and neutral standing radiographs using the Meyerding technique. Interobserver and intraobserver correlation coefficients were calculated. The difference in amount of translation was compared between 1) flexion and extension standing radiographs and 2) neutral standing radiograph and supine MRI. The proportion of patients with dynamic instability, defined as a ≥ 3 mm difference in the amount of translation measured on different imaging modalities, was reported. Correlation between amount of dynamic instability and change in back pain and leg pain 1 year after decompression and instrumented fusion was analyzed using multivariate regression analysis.

RESULTS

Fifty-six patients were included in this study. The mean patient age was 57.1 years, and 55.4% of patients were female. The most commonly affected levels were L4-5 (60.7%) and L5-S1 (30.4%). The average translations measured on flexion standing radiograph, extension standing radiograph, neutral standing radiograph, and supine MRI were 12.5 mm, 11.9 mm, 10.1 mm, and 7.2 mm, respectively. The average difference between flexion and extension standing radiographs was 0.58 mm, with dynamic instability detected in 21.4% of patients. The average difference between neutral standing radiograph and supine MRI was 3.77 mm, with dynamic instability detected in 60.7% of patients. The intraobserver correlation coefficient ranged from 0.77 to 0.90 mm. The interobserver correlation coefficient ranged from 0.79 to 0.86 mm. In 44 patients who underwent decompression and instrumented fusion, the amount of dynamic instability between standing and supine imaging was significantly correlated with change in back pain (p < 0.001) and leg pain (p = 0.05) at the 12-month postoperative follow-up. There was no correlation between amount of dynamic instability between flexion and extension standing radiographs and postoperative back pain and leg pain.

CONCLUSIONS

More patients were found to have dynamic instability by using neutral standing radiograph and supine MRI. In patients who received decompression and instrumented fusion, there was a significant correlation between dynamic instability on neutral standing radiograph and supine MRI and change in back pain and leg pain at 12 months.

A comparison of minimally invasive transforaminal lumbar interbody fusion and decompression alone for degenerative lumbar spondylolisthesis

OBJECTIVE

The optimal minimally invasive surgery (MIS) approach for grade 1 lumbar spondylolisthesis is not clearly elucidated. In this study, the authors compared the 24-month patient-reported outcomes (PROs) after MIS transforaminal lumbar interbody fusion (TLIF) and MIS decompression for degenerative lumbar spondylolisthesis.

METHODS

A total of 608 patients from 12 high-enrolling sites participating in the Quality Outcomes Database (QOD) lumbar spondylolisthesis module underwent single-level surgery for degenerative grade 1 lumbar spondylolisthesis, of whom 143 underwent MIS (72 MIS TLIF [50.3%] and 71 MIS decompression [49.7%]). Surgeries were classified as MIS if there was utilization of percutaneous screw fixation and placement of a Wiltse plane MIS intervertebral body graft (MIS TLIF) or if there was a tubular decompression (MIS decompression). Parameters obtained at baseline through at least 24 months of follow-up were collected. PROs included the Oswestry Disability Index (ODI), numeric rating scale (NRS) for back pain, NRS for leg pain, EuroQol-5D (EQ-5D) questionnaire, and North American Spine Society (NASS) satisfaction questionnaire. Multivariate models were constructed to adjust for patient characteristics, surgical variables, and baseline PRO values.

RESULTS

The mean age of the MIS cohort was 67.1 ± 11.3 years (MIS TLIF 62.1 years vs MIS decompression 72.3 years) and consisted of 79 (55.2%) women (MIS TLIF 55.6% vs MIS decompression 54.9%). The proportion in each cohort reaching the 24-month follow-up did not differ significantly between the cohorts (MIS TLIF 83.3% and MIS decompression 84.5%, p = 0.85). MIS TLIF was associated with greater blood loss (mean 108.8 vs 33.0 ml, p < 0.001), longer operative time (mean 228.2 vs 101.8 minutes, p < 0.001), and longer length of hospitalization (mean 2.9 vs 0.7 days, p < 0.001). MIS TLIF was associated with a significantly lower reoperation rate (14.1% vs 1.4%, p = 0.004). Both cohorts demonstrated significant improvements in ODI, NRS back pain, NRS leg pain, and EQ-5D at 24 months (p < 0.001, all comparisons relative to baseline). In multivariate analyses, MIS TLIF—as opposed to MIS decompression alone—was associated with superior ODI change (β = −7.59, 95% CI −14.96 to −0.23; p = 0.04), NRS back pain change (β = −1.54, 95% CI −2.78 to −0.30; p = 0.02), and NASS satisfaction (OR 0.32, 95% CI 0.12–0.82; p = 0.02).

CONCLUSIONS

For symptomatic, single-level degenerative spondylolisthesis, MIS TLIF was associated with a lower reoperation rate and superior outcomes for disability, back pain, and patient satisfaction compared with posterior MIS decompression alone. This finding may aid surgical decision-making when considering MIS for degenerative lumbar spondylolisthesis.

Utility of Supine Lateral Radiographs for Assessment of Lumbar Segmental Instability in Degenerative Lumbar Spondylolisthesis

STUDY DESIGN

Retrospective chart review OBJECTIVE.: To determine whether supine lateral radiographs increase the amount of segmental instability visualized in single-level lumbar degenerative spondylolisthesis, when compared to traditional lateral flexion-extension radiographs. We hypothesized that supine radiographs increase the amount of segmental instability seen in single-level lumbar spondylolisthesis when compared to flexion-extension.

SUMMARY OF BACKGROUND DATA

Accurate evaluation of segmental instability is critical to the management of lumbar spondylolisthesis. Standing flexion-extension lateral radiographs are routinely obtained, as it is believed to precipitate the forward-backward motion of the segment; however, recent studies with magnetic resonance imaging and computed tomography have shown that the relaxed supine position can facilitate the reduction of the anterolisthesed segment. Here, we show that inclusion of supine lateral radiographs increases the amount of segmental instability seen in single-level lumbar spondylolisthesis when compared to traditional lateral radiographs.

METHODS

Supine lateral radiographs were added to the routine evaluation (standing neutral/flexion/extension lateral radiographs) of symptomatic degenerative spondylolisthesis at our institution. In this retrospective study, 59 patients were included. The amount of listhesis was measured and compared on each radiograph: standing neutral lateral ("neutral"), standing flexion lateral ("flexion"), standing extension lateral ("extension"), and supine lateral ("supine").

RESULTS

A total of 59 patients (51 women, 8 men), with a mean age of 63.0 years (±9.85 yr) were included. The mean mobility seen with flexion-extension was 5.53 ± 4.11. The mean mobility seen with flexion-supine was 7.83% ± 4.67%. This difference was significant in paired t test (P = 0.00133), and independent of age and body mass index. Maximal mobility was seen between flexion and supine radiographs in 37 patients, between neutral and supine radiographs in 11 cases, and between traditional flexion-extension studies in 11 cases.

CONCLUSION

Supine radiograph demonstrates more reduction in anterolisthesis than the extension radiograph. Incorporation of a supine lateral radiograph in place of extension radiograph can improve our understanding of segmental mobility when evaluating degenerative spondylolisthesis.

LEVEL OF EVIDENCE

3.

Minimum ten-year follow-up of spinal stenosis with degenerative spondylolisthesis treated with decompression and dynamic stabilization

Background

The Dynesys system remains the most widely implanted posterior non-fusion pedicle screw system. Various study designs used in investigations with good to excellent short- and mid-term results have been reported in the current literature. However, there is a lack of information concerning long-term outcomes following treatment for spinal stenosis with degenerative spondylolisthesis.

Methods

The aim of our study was twofold. Firstly, to assess whether the dynamic stabilization in situ with the Dynesys System without bone grafting provides enough stability to prevent progression of spondylolisthesis and secondarily to maintain significant clinical improvement in a long-term follow-up (FU). Therefore, the consecutive patients due to inclusion criterions underwent interlaminar decompression and stabilization with Dynesys instrumentation. Patients were evaluated clinically and radiologically after a minimum FU of 10 years.

Results

At FU, the mean low back pain (LBP) post-operatively and leg pain (LP) post-operatively on visual analog scale (VAS) and North American Spine Society (NASS) improved significantly (P<0.001) compared to preoperative examination. The mean value of NASS neurogenic symptoms (19.13% and 4.72%) and activity subscores were 23.13% and 10.74% respectively. In plain and functional radiographs the mean listhesis grade in neutral position was 11.11%, 11.8% in reclination and 11.63% in inclination. There were 17 and 8 patients with progressing degenerative osteochondrosis/listhesis at adjacent segments.

Conclusions

Decompression and single and double level dynamic in situ stabilization with the Dynesys System demonstrate good clinical and radiological long-term results in elderly patients.

Despite worse baseline status depressed patients achieved outcomes similar to those in nondepressed patients after surgery for cervical deformity

OBJECTIVE

Depression and anxiety have been demonstrated to have negative impacts on outcomes after spine surgery. In patients with cervical deformity (CD), the psychological and physiological burdens of the disease may overlap without clear boundaries. While surgery has a proven record of bringing about significant pain relief and decreased disability, the impact of depression and anxiety on recovery from cervical deformity corrective surgery has not been previously reported on in the literature. The purpose of the present study was to determine the effect of depression and anxiety on patients’ recovery from and improvement after CD surgery.

METHODS

The authors conducted a retrospective review of a prospective, multicenter CD database. Patients with a history of clinical depression, in addition to those with current self-reported anxiety or depression, were defined as depressed (D group). The D group was compared with nondepressed patients (ND group) with a similar baseline deformity determined by propensity score matching of the cervical sagittal vertical axis (cSVA). Baseline demographic, comorbidity, clinical, and radiographic data were compared among patients using t-tests. Improvement of symptoms was recorded at 3 months, 6 months, and 1 year postoperatively. All health-related quality of life (HRQOL) scores collected at these follow-up time points were compared using t-tests.

RESULTS

Sixty-six patients were matched for baseline radiographic parameters: 33 with a history of depression and/or current depression, and 33 without. Depressed patients had similar age, sex, race, and radiographic alignment: cSVA, T-1 slope minus C2–7 lordosis, SVA, and T-1 pelvic angle (p > 0.05). Compared with nondepressed individuals, depressed patients had a higher incidence of osteoporosis (21.2% vs 3.2%, p = 0.028), rheumatoid arthritis (18.2% vs 3.2%, p = 0.012), and connective tissue disorders (18.2% vs 3.2%, p = 0.012). At baseline, the D group had greater neck pain (7.9 of 10 vs 6.6 on a Numeric Rating Scale [NRS], p = 0.015), lower mean EQ-5D scores (68.9 vs 74.7, p < 0.001), but similar Neck Disability Index (NDI) scores (57.5 vs 49.9, p = 0.063) and myelopathy scores (13.4 vs 13.9, p = 0.546). Surgeries performed in either group were similar in terms of number of levels fused, osteotomies performed, and correction achieved (baseline to 3-month measurements) (p < 0.05). At 3 months, EQ-5D scores remained lower in the D group (74.0 vs 78.2, p = 0.044), and NDI scores were similar (48.5 vs 39.0, p = 0.053). However, neck pain improved in the D group (NRS score of 5.0 vs 4.3, p = 0.331), and modified Japanese Orthopaedic Association (mJOA) scores remained similar (14.2 vs 15.0, p = 0.211). At 6 months and 1 year, all HRQOL scores were similar between the 2 cohorts. One-year measurements were as follows: NDI 39.7 vs 40.7 (p = 0.878), NRS neck pain score of 4.1 vs 5.0 (p = 0.326), EQ-5D score of 77.1 vs 78.2 (p = 0.646), and mJOA score of 14.0 vs 14.2 (p = 0.835). Anxiety/depression levels reported on the EQ-5D scale were significantly higher in the depressed cohort at baseline, 3 months, and 6 months (all p < 0.05), but were similar between groups at 1 year postoperatively (1.72 vs 1.53, p = 0.416).

CONCLUSIONS

Clinical depression was observed in many of the study patients with CD. After matching for baseline deformity, depression symptomology resulted in worse baseline EQ-5D and pain scores. Despite these baseline differences, both cohorts achieved similar results in all HRQOL assessments 6 months and 1 year postoperatively, demonstrating no clinical impact of depression on recovery up until 1 year after CD surgery. Thus, a history of depression does not appear to have an impact on recovery from CD surgery.

Scoping review to develop common data elements for lumbar spinal stenosis

BACKGROUND CONTEXT

Common data elements (CDE) represent an important tool for understanding and classifying health outcomes across settings. Although CDEs have been developed for a number of disorders, to date CDEs for lumbar spinal stenosis (LSS) have not been fully developed. To facilitate the identification of CDEs and measures to assess them, this technical study leverages the International Classification of Functioning, Disability and Health (ICF), peer-reviewed research, and a panel of experts to identify CDEs specific to LSS.

PURPOSE

The study aimed to define CDEs for disease characteristics and outcomes of LSS using the World Health Organization's ICF taxonomy, and to facilitate the selection of assessment instruments for research and clinical care.

DESIGN

This is a scoping review using a modified Delphi approach with a technical expert panel composed of clinicians and scientists representing the academia, policy and advocacy stakeholders, and professional associations with expertise in LSS.

METHODS

This is a scoping review to identify measures that assess LSS symptoms. Thirty-one subject matter experts (SMEs) prioritized ICF codes and evaluated instruments measuring specific domains. We used a modified Delphi technique to evaluate item-level content and achieve consensus.

RESULTS

SMEs prioritized 53 ICF codes; 3 received 100% endorsement, 27 received ≥90% endorsement, whereas the remaining 23 received ≥80% endorsement. Prioritized ICF codes represent diverse domains, including pain, activities and participation, and emotional well-being. The review yielded 58 instruments; we retained 24 for content analysis.

CONCLUSIONS

The retained instruments adequately represent the ICFs activities and participation, and body function domains. Body structure and environmental factors were assessed infrequently. Adoption of these CDEs may guide clinical decision making and facilitate comparative effectiveness trials for interventions focused on LSS.

Decompression plus fusion versus decompression alone for degenerative lumbar spondylolisthesis: a systematic review and meta-analysis

PURPOSE

To compare the clinical effectiveness of decompression plus fusion and decompression alone for patients with degenerative lumbar spondylolisthesis, a systematic review and meta-analysis of all available evidence was performed.

METHODS

A search of the literature was conducted on PubMed/MEDLINE, EMBASE, and the Cochrane Collaboration Library. Relevant studies comparing decompression plus fusion and decompression alone were selected according to eligibility criteria. Predefined endpoints were extracted and meta-analyzed from the identified studies.

RESULTS

Four randomized controlled trials and 13 observational studies were eligible. The pooled data revealed that fusion was associated with significantly higher rates of satisfaction and lower leg pain scores when compared with decompression alone. However, fusion significantly increased the intraoperative blood loss, operative time and hospital stay. Both techniques had similar ODI, back pain scores, complication rate, and reoperation rate.

CONCLUSIONS

Based on the available evidence, decompression plus fusion maybe be better than decompression alone in the treatment of degenerative spondylolisthesis. Fusion had advantages of improvement of clinical satisfaction, as well as reduction of postoperative leg pain, with similar complication rate to decompression alone.

Feasibility of Percutaneous Posterolateral Spinal Fusion With Recombinant Bone Morphogenetic Protein-2 (rhBMP-2): A Comparison With Standard Methods Using an Animal Model Study

BACKGROUND CONTEXT

The clinical application of recombinant bone morphogenetic protein in spinal surgery has been shown to be safe and effective. However, its use in minimally invasive spine surgery has been limited to anterior interbody fusion procedures. To date, no study has evaluated the feasibility of percutaneous posterolateral fusion in the spine utilizing recombinant bone morphogenetic protein-2 (rhBMP-2).

PURPOSE

To evaluate the feasibility of percutaneous posterolateral fusion in the spine utilizing rhBMP-2.

STUDY DESIGN

Animal study.

METHODS

This is an animal research model involving 32 New Zealand white rabbits stratified into 4 study groups: control, autogenous iliac crest bone graft (ICBG), demineralized bone matrix (DBM), and rhBMP-2 groups, with 8 study subjects per group. The rhBMP-2 group was subdivided into the open technique (right side) and the percutaneous technique groups (left side). Fusion was graded at 6 weeks and 3 months after plain radiography, computed tomography, and clinical assessment with the following grading system: grade A, no bone formation; grade B, non-bridging bone formation; grade C, fusion; and grade D, fusion with ectopic bone formation.

RESULTS

No fusion was noted in the placebo and the DBM groups. However, in the DBM group, bone formation occurred in 37.5% of the subjects. The rhBMP-2 group had a higher fusion rate compared with the ICBG group at 6 weeks and 3 months. The fusion rate for the ICBG, the rhBMP-2 (open), and the rhBMP-2 (percutaneous) groups were 37.5%, 87.5%, and 50.0% at 6 weeks and 50.0%, 100.0%, and 62.5% at 3 months, respectively. Ectopic bone formation occurred in 12.5% of the cases in the rhBMP-2 (percutaneous) group and in 25.0% of the cases in the rhBMP-2 (open) group.

CONCLUSIONS

Usage of rhBMP-2 is feasible for percutaneous posterolateral fusion of the lumbar spine in this animal model. However, a more precise delivery system might improve the fusion rate when the percutaneous technique is used. A significant rate of ectopic bone formation occurred when rhBMP-2 was used.

Kinematic analysis of diseased and adjacent segments in degenerative lumbar spondylolisthesis

BACKGROUND CONTEXT

Degenerative spondylolisthesis is a common pathologic condition that leads to lumbar instability and significant clinical symptoms. The effect of this pathology on adjacent lumbar motion segments, however, has not yet been studied.

PURPOSE

To characterize the motion characteristics of lumbar degenerative spondylolisthesis at both the diseased and adjacent levels in patients with low-grade, single-level lumbar degenerative spondylolisthesis using kinetic magnetic resonance imaging (kMRI).

STUDY DESIGN

Retrospective study of patient kMRIs.

PATIENT SAMPLE

One-hundred twelve patient MRIs with low-grade, single-level lumbar spondylolisthesis were included.

OUTCOME MEASURES

Angular and translational motion.

METHODS

This study compared 112 patients diagnosed with low-grade (Grade 1 or 2), single-level lumbar degenerative spondylolisthesis at L3-L4, L4-L5, or L5-S1 with 296 control patients without spondylolisthesis. Angular and translational motion were measured using patient kMRIs. The level of slip was graded according to the Meyerding classification system, and disc degeneration was classified according to the Pfirrmann system. Instability was defined as translational motion greater than 4 mm.

RESULTS

Lumbar hypomobility was often present regardless of the level of degenerative spondylolisthesis. A slip at L3-L4 resulted in the largest decrease in lumbar range of motion. Instability at the diseased level was most common at L3-L4 (36%), followed by L5-S1 (31%) and L4-L5 (30%). Instability at the adjacent segments was most frequent at L4-L5 (49%), followed by L5-S1 (34%) and L3-L4 (23%). Patients with stable spondylolisthesis generally had decreased angular motion at all lumbar levels. Translational motion at the diseased level was consistently increased. Disc degeneration was significantly greater at the level of slip for the L3-L4 and L4-L5 spondylolisthesis groups and equal to the control group in the L5-S1 group. There was no significant difference in disc degeneration at adjacent segments in L3-L4 and L4-L5 degenerative spondylolisthesis patients, but there was a significant decrease with an L5-S1 slip.

CONCLUSIONS

There were a similar percentage of patients in each degenerative spondylolisthesis group with lumbar instability. Angular motion decreased at the diseased level with L3-L4 and L5-S1 spondylolisthesis, but increased with L4-L5 spondylolisthesis. Translational motion, however, increased at the diseased level in all three groups. There was compensatory hypermobility at adjacent levels in patients with unstable spondylolisthesis at L3-L4 and L4-L5, but not at L5-S1.

Imaging characteristics of "dynamic" versus "static" spondylolisthesis: analysis using magnetic resonance imaging and flexion/extension films

BACKGROUND CONTEXT

Traditionally, the "dynamic" and "static" types of spondylolisthesis have been lumped into a single group in the literature. The goal of this study was to define the radiographic characteristics of "dynamic" and "static" spondylolisthesis with the use of magnetic resonance imaging (MRI) and flexion/extension radiographs.

PURPOSE

Describe the characteristic findings present on MRI and flexion/extension radiographs that are associated with dynamic versus static spondylolisthesis.

STUDY DESIGN

Retrospective radiographic/imaging study.

METHODS

From 2009 to 2011, patients who underwent elective primary posterior spinal fusion for the diagnosis of spondylolisthesis had their plain films assessed for the degree of spondylolisthesis and were designated "dynamic" or "static," as defined by historical measures. Axial and sagittal T2 MRIs were evaluated for associated facet fluid (FF), facet cysts, interspinous fluid (ISF), and facet hypertrophy. These finding were then statistically evaluated for associations between dynamic and static spondylolisthesis on flexion/extension radiographs and characteristic MRI findings.

RESULTS

Ninety patients were included in the study with 114 levels examined for spondylolisthesis. Patients with greater than 3 mm of instability on flexion/extension films were more likely to have FF (p=.018) and ISF (p<.001). Of the patients who had a greater than 3 mm of instability, 39.5% did not demonstrate spondylolisthesis on the sagittal MRI reconstruction. If ISF was present on MRI, there was a positive predictive value of 69.0% that there would be greater than 3 mm instability on flexion/extension films. Absence of FF on MRI had a positive predictive value of 75.6% for instability less than 3 mm on flexion/extension films. In the presence of ISF on MRI, the likelihood ratio of finding more than 3 mm of instability on flexion/extension films was 3.68. The presence of FF on MRI had a likelihood ratio of 1.43 for instability. A total of 36.8% of all spondylolisthesis reduced when supine on MRI.

CONCLUSIONS

The presence of FF and/or ISF is associated with instability greater than 3 mm in flexion/extension radiographs.

The long-term outcome of patients treated operatively and non-operatively for scoliosis deformity secondary to spina bifida

The purpose of this study was to evaluate the long-term outcome of adults with spina bifida cystica (SBC) who had been treated either operatively or non-operatively for scoliosis during childhood.

We reviewed 45 patients with a SBC scoliosis (Cobb angle ≥ 50º) who had been treated at one of two children’s hospitals between 1991 and 2007. Of these, 34 (75.6%) had been treated operatively and 11 (24.4%) non-operatively. After a mean follow-up of 14.1 years (standard deviation (sd) 4.3) clinical, radiological and health-related quality of life (HRQOL) outcomes were evaluated using the Spina Bifida Spine Questionnaire (SBSQ) and the 36-Item Short Form Health Survey (SF-36).

Although patients in the two groups were demographically similar, those who had undergone surgery had a larger mean Cobb angle (88.0º (sd 20.5; 50.0 to 122.0); versus 65.7º (sd 22.0; 51.0 to 115.0); p < 0.01) and a larger mean clavicle–rib intersection difference (12.3 mm; (sd 8.5; 1 to 37); versus 4.1 mm, (sd 5.9; 0 to 16); p = 0.01) than those treated non-operatively. Both groups were statistically similar at follow-up with respect to walking capacity, neurological motor level, sitting balance and health-related quality of life (HRQOL) outcomes.

Spinal fusion in SBC scoliosis corrects coronal deformity and stops progression of the curve but has no clear effect on HRQOL.

Cite this article: Bone Joint J 2014; 96-B:1244–51

Degenerative spondylolisthesis does not affect the outcome of unilateral laminotomy with bilateral decompression in patients with lumbar stenosis

STUDY DESIGN

Prospective subcohort study.

OBJECTIVE

To determine whether preoperative presence of degenerative spondylolisthesis worsens the outcome of patients undergoing unilateral laminotomy with bilateral decompression for lumbar stenosis.

SUMMARY OF BACKGROUND DATA

The standard surgical treatment for degenerative spondylolisthesis with lumbar stenosis is lumbar fusion after standard laminectomy. Although this strategy is widely adopted, it is not supported by class I evidence. This strategy assumes that degenerative spondylolisthesis worsens the outcome of laminectomy by causing postoperative instability. However, instability may be reduced or prevented by the use of less invasive decompression techniques.

METHODS

To test the hypothesis that preoperative degenerative spondylolisthesis worsens the outcome of less invasive lumbar decompression, we performed a prospective cohort study of 165 consecutive patients who underwent unilateral laminotomy with bilateral decompression at our institution. The patients were prospectively followed with a standardized questionnaire, 36-Item Short Form Health Survey, and standing lumbar radiographs for a maximum follow-up period of 5 years. According to the presence or absence of degenerative spondylolisthesis, the patients were divided into 2 groups: an olisthesis group and a nonolisthesis group.

RESULTS

The average 36-Item Short Form Health Survey physical score and bodily pain score improved substantially immediately after surgery. This improvement was maintained up to 5 years postoperatively. Progression of slippage was uncommon in both groups, with an overall incidence of 8% at 5 years of follow-up. There was no significant difference in the average physical score, the bodily pain score, or the rate of progression of slippage between the olisthesis and nonolisthesis groups.

CONCLUSION

Our study thus indicates that preoperative degenerative spondylolisthesis does not worsen the outcome of patients with lumbar stenosis undergoing unilateral laminotomy with bilateral decompression. These results suggest that lumbar fusion is often unnecessary in patients with degenerative spondylolisthesis and lumbar stenosis if the posterior decompression technique is unilateral laminotomy with bilateral decompression.

LEVEL OF EVIDENCE

2.

Lumbar facet joint motion in patients with degenerative spondylolisthesis

STUDY DESIGN

Controlled laboratory study.

OBJECTIVE

To investigate the in vivo biomechanical effect of degenerative lumbar spondylolisthesis (DLS) on the motion of the facet joint during various functional weight-bearing activities.

SUMMARY OF BACKGROUND DATA

Although the morphologic changes of the facet joints in patients with DLS have been reported in a few studies, no data have been reported on the kinematics of these facet joints.

METHODS

Ten patients with DLS at L4-L5 were studied. Each patient underwent a magnetic resonance imaging scan to obtain 3-dimensional models of the lumbar vertebrae from L2-L5 and a dual fluoroscopic imaging scan in different postures: flexion-extension, left-right bending, and left-right torsion. The positions of the vertebrae were reproduced by matching the magnetic resonance imaging-based vertebral models to the fluoroscopic images. The kinematics of the facet joint and the ranges of motion were compared with those of healthy subjects and those of patients with degenerative disk diseases (DDD) previously published.

RESULTS

In DLS patients, the range of rotation of the facet joints was significantly less at the DLS level (L4-L5) than that at the adjacent levels (L2-L3 and L3-L4), whereas the range of translation was similar at all levels. The range of rotation at the facet joints of the DLS level decreased compared with those of both the DDD patients and healthy subjects at the corresponding vertebral level (L4-L5), whereas no significant difference was found in the range of translation. The range of motion of facet joints in DLS and in DDD patients was similar at the adjacent levels (L2-L3 and L3-L4).

CONCLUSIONS

The range of rotation decreased at the facet joints at the DLS level (L4-L5) in patients compared with those in healthy subjects and DDD patients. This decrease in range of rotation implies that the DLS disease may cause restabilization of the joint. The data may help the selection of conservative treatment or different surgical techniques for the DLS patients.

Radiographic predictors of delayed instability following decompression without fusion for degenerative Grade I lumbar spondylolisthesis

Object

It is not known whether adding fusion to lumbar decompression is necessary for all patients undergoing surgery for degenerative lumbar spondylolisthesis with symptomatic stenosis. Determining specific radiographic traits that might predict delayed instability following decompression surgery might guide clinical decision making regarding the utility of up-front fusion in patients with degenerative Grade I spondylolisthesis.

Methods

Patients with Grade I degenerative lumbar spondylolisthesis (3–14 mm) with symptomatic stenosis were prospectively enrolled from a single site between May 2002 and September 2009 and treated with decompressive laminectomy without fusion. Patients with mechanical back pain or with gross motion (> 3 mm) on flexion-extension lumbar radiographs were excluded. The baseline radiographic variables measured included amount of slippage, disc height, facet angle, motion at spondylolisthesis (flexion-extension), and sagittal rotation angle. Data were analyzed using multivariate forward selection stepwise logistic regression, chi-square tests, Student t-test, and ANOVA.

Results

Forty patients were enrolled and treated with laminectomy without fusion, and all patients had complete radiographic data sets that were available for analysis. Reoperation was performed in 15 (37.5%) of 40 patients, with a mean follow-up duration of 3.6 years. Reoperation was performed for pain caused by instability at the index level in all 15 cases. Using multivariate stepwise logistic regression with a threshold p value of 0.35, motion at spondylolisthesis, disc height, and facet angle were predictors of reoperation following surgery. Facet angle > 50° was associated with a 39% rate of reoperation, disc height > 6.5 mm was associated with a 45% rate of reoperation, and motion at spondylolisthesis > 1.25 mm was associated with a 54% rate of reoperation. Patients with all 3 risk factors for instability had a 75% rate of reoperation, whereas patients with no risk factors for instability had a 0% rate of reoperation (p = 0.14).

Conclusions

Patients with motion at spondylolisthesis > 1.25 mm, disc height > 6.5 mm, and facet angle > 50° are more likely to experience instability following decompression surgery for Grade I lumbar spondylolisthesis. Identification of key risk factors for instability might improve patient selection for decompression without fusion surgery. Clinical trial registration no.: NCT00109213

Pedicle-Screw-Based Dynamic Systems and Degenerative Lumbar Diseases: Biomechanical and Clinical Experiences of Dynamic Fusion with Isobar TTL

Dynamic systems in the lumbar spine are believed to reduce main fusion drawbacks such as pseudarthrosis, bone rarefaction, and mechanical failure. Compared to fusion achieved with rigid constructs, biomechanical studies underlined some advantages of dynamic instrumentation including increased load sharing between the instrumentation and interbody bone graft and stresses reduction at bone-to-screw interface. These advantages may result in increased fusion rates, limitation of bone rarefaction, and reduction of mechanical complications with the ultimate objective to reduce reoperations rates. However published clinical evidence for dynamic systems remains limited. In addition to providing biomechanical evaluation of a pedicle-screw-based dynamic system, the present study offers a long-term (average 10.2 years) insight view of the clinical outcomes of 18 patients treated by fusion with dynamic systems for degenerative lumbar spine diseases. The findings outline significant and stable symptoms relief, absence of implant-related complications, no revision surgery, and few adjacent segment degenerative changes. In spite of sample limitations, this is the first long-term report of outcomes of dynamic fusion that opens an interesting perspective for clinical outcomes of dynamic systems that need to be explored at larger scale.

Evaluation of health-related quality of life in patients candidate for spine and other musculoskeletal surgery

INTRODUCTION

Despite the high prevalence of musculoskeletal diseases, in Spain there are few data about how these conditions affect the quality of life of individuals. The objective of this study was to assess the quality of life (QOL) of patients candidate for orthopedic surgical treatment using an age-gender adjusted method of QOL scores.

MATERIALS AND METHODS

The SF-36 Health Survey was administered to 538 patients candidate for surgery between surgical treatment was classified in four groups (lumbar disease, cervical disease, knee arthroplasty, and hip arthroplasty). Associated morbidities were collected retrospectively for all cases using the Charlson co-morbidity index. Univariate, bivariate, and multivariate statistical analyses were done to compare the four groups to each other, to the general population mean, and to the age and gender-adjusted population mean.

RESULTS

234 men and 304 women whose mean age was 58.78 years (19-89) were assessed. Patients candidate for some kind or lumbar surgery had the worst scores in all physical and mental scales as compared to the other disease groups. Patients candidate for knee arthroplasty, had the best quality of life scores in all scales, compared to the other disease groups. Medical conditions had no influence over the summary measures.

CONCLUSION

Presenting the results of SF-36 in standard deviations from the age- and gender-adjusted population mean (T values) leads to a better appreciation of the differences between the various diseases. Patients candidate for surgery of the lumbar spine had a worse QOL, while the QOL in patients candidate for knee arthroplasty was the least affected.

Skipping posterior dynamic transpedicular stabilization for distant segment degenerative disease

Objective. To date, there is still no consensus on the treatment of spinal degenerative disease. Current surgical techniques to manage painful spinal disorders are imperfect. In this paper, we aimed to evaluate the prospective results of posterior transpedicular dynamic stabilization, a novel surgical approach that skips the segments that do not produce pain. This technique has been proven biomechanically and radiologically in spinal degenerative diseases. Methods. A prospective study of 18 patients averaging 54.94 years of age with distant spinal segment degenerative disease. Indications consisted of degenerative disc disease (57%), herniated nucleus pulposus (50%), spinal stenosis (14.28%), degenerative spondylolisthesis (14.28%), and foraminal stenosis (7.1%). The Oswestry Low-Back Pain Disability Questionnaire and visual analog scale (VAS) for pain were recorded preoperatively and at the third and twelfth postoperative months. Results. Both the Oswestry and VAS scores showed significant improvement postoperatively (P < 0.05). We observed complications in one patient who had spinal epidural hematoma. Conclusion. We recommend skipping posterior transpedicular dynamic stabilization for surgical treatment of distant segment spinal degenerative disease.

A comparison of unilateral laminectomy with bilateral decompression and fusion surgery in the treatment of grade I lumbar degenerative spondylolisthesis

BACKGROUND

Although unilateral laminectomy and bilateral decompression (ULBD) is effective in the treatment of degenerative spondylolisthesis (DSPL), few reports have compared the outcomes of ULBD and instrumented fusion for the treatment of DSPL. We describe here the clinical and radiological outcomes of ULBD and instrumented fusion surgery for the treatment of DSPL after a minimum 3-year follow-up.

METHODS

We retrospectively analyzed the outcomes of 47 DSPL patients with radicular pain who underwent ULBD or instrumented fusion between January 2005 and December 2007. Clinical outcomes were assessed using the numeric rating scale (NRS) for back and leg pain, the Oswestry Disability Index (ODI), and Short Form-36 Health Survey (SF-36). Radiological outcomes of ULBD were analyzed by determining changes in slippage, disc height translation, and angular difference on simple and dynamic X-rays.

RESULTS

The mean NRS of back pain showed a significantly greater decrease in the fusion than the ULBD group, whereas the mean NRS of leg pain, mean ODI, and mean physical component summary and mental component summary of the SF-36 decreased similarly in the ULBD and fusion groups. Radiologically, the ULBD group showed a 2.1 ± 3.10% change in mean slippage, a 0.15 ± 1.58 mm change in mean translation, a -0.91 ± 4.48° change in mean angular difference, and a -1.83 ± 1.69 mm change in mean disc height. In the ULBD group, three patients had residual pain and three had recurrent pain. In comparison, no patient in the fusion group reported residual pain, whereas five patients experienced recurrent radicular pain caused by adjacent segmental disease.

CONCLUSIONS

Our findings suggest that ULBD is the recommendable procedure for the treatment of patients with grade I DSPL who have mainly radicular pain. Although the two groups showed similar clinical outcomes overall, radiological degeneration was not as serious after ULBD treatment. In our analysis, foraminal stenosis is a contraindication for ULBD in the treatment of grade I DSPL.

The first clinical trial of beta-calcium pyrophosphate as a novel bone graft extender in instrumented posterolateral lumbar fusion

Background

Porous β-calcium pyrophosphate (β-CPP) was developed to improve the fusion success of posterolateral lumbar fusion (PLF). The possibility of accomplishing PLF using a mixture of porous β-CPP and iliac bone was studied. This paper reports the radiologic results of PLF using the β-CPP plus autograft for lumbar degenerative disease as a bone graft extender.

Methods

A prospective, case-matched, radiographic study evaluating the results of short segment lumbar fusion using a β-CPP plus autograft was performed to compare the efficacy of β-CPP plus autograft with that of an autograft alone for short segment lumbar fusion. Thirty one consecutive patients (46 levels) underwent posterolateral fusion with pedicle screw fixation and additional posterior lumbar interbody fusion. In all patients, 3 mL of β-CPP plus 3 mL of autogenous bone graft was placed randomly in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other. The fusion rates, volumes of fusion masses, and bone absorption percentage were evaluated postoperatively using simple radiographs and 3 dimensional computed tomography (3D-CT) scans.

Results

The control sides treated with an autograft showed significantly better Lenke scores than the study sides treated with β-CPP at 3 and 6 months postoperatively, but there was no difference between the two sides at 12 months. The fusion rates (confirmed by 3D-CT) were 87.0% in the β-CPP group and 89.1% in the autograft group, which were not significantly different. The fusion mass volumes and bone absorption percentage at 12 months postoperatively were 2.49 mL (58.4%) and 1.89 mL (69.5%) for the β-CPP and autograft groups, respectively, and mean fusion mass volume was significantly higher in the β-CPP group.

Conclusions

β-CPP combined with an autograft is as effective as autologous bone for grafting during instrumented posterolateral spinal fusion. These findings suggest that β-CPP bone chips can be used as a novel bone graft extender for short-segment posterolateral spinal fusion.

Assessing dimensionality and responsiveness of outcomes measures for patients with low back pain

OBJECTIVE

To provide a systematic literature review of the responsiveness of patient-reported health outcomes measures for the evaluation of low back pain (LBP).

METHODS AND DESIGN

Searches of MEDLINE and EMBASE were performed for articles published in English through June 29, 2009 using the search terms "back pain" or "low back pain" and "questionnaires" or "instrument" or "survey" or "measure" or "patient report outcome." Information on responsiveness was gathered through additional measure-specific searches that included the measure name, first author of the original paper, and "respons*" or "sensit*." Responsiveness was determined based on use of a receiver operating characteristics curve or effect size statistics.

RESULTS

Of 43 identified measures, 31 were reported as being responsive to treatment or clinical change, 25 of which were evaluated for responsiveness using methods considered adequate. When considering both the responsiveness evaluation and the underlying factor structure, 13 measures were identified as being adequately validated for use in evaluating responsiveness in the research or clinical practice setting. The majority of the LBP outcome assessment studies were comprised of patients undergoing physical and interventional therapies from clinical practice and clinical trials. The Roland Morris Disability Questionnaire and the Oswestry Disability Index were the most comprehensively validated measures with respect to responsiveness.

CONCLUSIONS

We identified 13 measures of LBP that can be used to evaluate responsiveness to change. Choice of a measure warrants careful evaluation of its construct and responsiveness properties in order to maximize the observed impact on pain and functional improvement in subjects with LBP.

Comparison of posterior dynamic and posterior rigid transpedicular stabilization with fusion to treat degenerative spondylolisthesis

This article describes the clinical and radiological outcomes of a comparison of posterior dynamic transpedicular stabilization and posterior rigid transpedicular stabilization with fusion after decompression in the treatment of degenerative spondylolisthesis. This prospective clinical and radiologic study was conducted between 2004 and 2007 and included 46 patients, of whom 33 were women (71.7%) and 13 were men (28.3%). Mean patient age was 61.67+/-10.80 years (range, 45-89 years). Twenty-six patients who underwent lumbar decompression and posterior dynamic transpedicular stabilization were followed for a mean of 38 months (range, 24-55 months). In the fusion group, 20 patients who underwent lumbar decompression and rigid stabilization with fusion were followed for a mean of 44 months (range, 26-64 months). The intervertebral space measurements of the dynamic group at the preoperative examination and at 12 and 24 months postoperatively were statistically significantly higher than the intervertebral space measurements of the fusion group (P<.05). In the dynamic group, complications occurred in 2 patients; the first was a screw malposition, which was improved with revision surgery within 1 month of the initial surgery, and the second was a fusion performed in the second year in 1 patient because the patient reported continued pain. In the fusion group, adjacent segment disease was observed in 1 patient, with subsequent reoperation. Lumbar decompression and posterior dynamic transpedicular stabilization yield satisfactory results in the treatment of degenerative lumbar spondylolisthesis and can be considered a valid alternative to fusion.

Rating scales for low back pain

INTRODUCTION

During the past decades several rating scales have been developed to assess the functional status of patients with low back pain.

METHODS

We performed a search using the keywords 'spine' in combination with 'scoring system', 'scale', 'scores', 'outcome assessment', 'low back pain' and 'clinical evaluation'.

RESULTS

Twenty-eight scoring systems are currently available for the evaluation of low back pain. Each of them evaluates low back pain using specific variables. All these scoring systems are presented.

DISCUSSION

Although many scoring systems have been used to evaluate the back function, we are still far from a single outcome evaluation system that is reliable, valid and sensitive to clinically relevant changes, taken into account both patients' and physicians' perspective and is short and practical to use.

CONCLUSION

Further studies are required to evaluate the reliability, validity and sensitivity of the low back pain scoring systems used in the common clinical practice.

A prospective consecutive study of instrumented posterolateral lumbar fusion using synthetic hydroxyapatite (Bongros-HA) as a bone graft extender

A prospective, single institution, clinical case-matched, radiographic study was undertaken. Thirty-two patients underwent posterior lumbar interbody fusion with cages containing laminectomized bone chips and posterolateral lumbar fusion with pedicle screws. Autogenous bone graft (3 mL) plus 3 mL of hydroxyapatite was placed in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other side. Bony union, volumes of fusion mass, and bone absorption rates were postoperatively evaluated using simple radiographs and 3D-CT scans. Average postoperative Lenke scores at 3 and 6 months in the hydroxyapatite group were statistically higher than in the autograft group, but at 12 months no difference was found between the hydroxyapatite and autograft groups in terms of fusion rate. Complete fusion rates by 3D-CT were 86.7% in the hydroxyapatite group and 88.9% in the autograft group, which are not significantly different. Volumes of fusion mass and bone absorption rates at 12 months were 2.35 mL in the hydroxyapatite group and 1.31 mL in the autograft group. The mean fusion mass volume was greater in the hydroxyapatite group than in the autograft group. Lumbar posterolateral fusion using a mixture of hydroxyapatite artificial bone and autogenous bone graft showed good bony union similar to that shown with autogenous bone only. This study suggests that hydroxyapatite bone chips could be used usefully as a bone-graft extender in short-segment posterolateral spinal fusion.

The morbidity of an anterior thoracolumbar approach: adult spinal deformity patients with greater than five-year follow-up

STUDY DESIGN

Retrospective study.

OBJECTIVE

To analyze the complications and patient satisfaction related to an anterior thoracolumbar approach in the treatment of adult spinal deformity.

SUMMARY OF BACKGROUND DATA

There is no long-term follow-up data on the effects of an anterior thoracolumbar approach on adult spinal deformity patients.

METHODS

A specific questionnaire was used to evaluate long-term follow-up (average, 10.3 years; range, 5-20.6) of 62 adult patients who underwent spinal deformity surgery performed through an anterior thoracolumbar approach. Twenty-six patients had over 10 years follow-up and 36 were between 5 and 10 years follow-up. The questionnaire was composed of detailed scar-related subquestions for pain, appearance, bulging, daily life, and patient's personal opinion of surgery. Postoperative Oswestry Disability Index (scores) were also obtained.

RESULTS

The average age and number of anterior fusion levels were 47.9 (range, 20-74) and 5.6 (range, 2-12), respectively. Although 82.2% patients were satisfied with the results of their surgery, in general, many of the patients were dissatisfied with aspects related to their anterior incision. For the pain domain, 20 patients (32.3%, 6 with >10 years follow-up, 14 patients with 5 years follow-up) had pain over their thoracolumbar scar, which they rated as moderate to severe. Twenty-seven patients (43.5%) had bulging of their scar region, 4 were surgically indicated for repair, and 1 had multiple surgical repairs. Twelve patients (19.4%) felt they had a poor outcome related to the postoperative appearance of their anterior wound. Fifteen patients (24.2%) showed limitations in activities of daily living due to their anterior incision. Three patients with >10 years of follow-up and 4 with >5 years of follow-up felt they were getting worse. The average Oswestry Disability Index score was 25.0 +/- 16.3 (range, 0-52) postoperative.

CONCLUSION

This is the first long-term (minimum 5 years) follow-up study focusing on patient outcomes after an anterior thoracolumbar approach for adult spinal deformity treatment. This approach appears to be associated with an appreciable high rate of postoperative pain (32.3%), bulging (43.5%), and functional disturbance (24.2%). Therefore, surgeons should use caution when recommending this approach to future adult spinal deformity patients.

In situ local autograft for instrumented lower lumbar or lumbosacral posterolateral fusion

This study evaluated the effectiveness of local in situ autografts in instrumented posterolateral fusion of the lower lumbar or lumbosacral spine for treating degenerative spondylolisthesis. The subjects were 182 degenerative spondylolisthesis patients with spinal canal stenosis who, in one operation, underwent lumbar laminectomy with two-level (L3-4, L4-5 or L5-S1) transpedicle screw/rod system instrumentation and posterolateral fusion using autogenous spinous processes and laminae as the only source of bone grafts. The surgical results were assessed clinically and radiologically. All patients received follow-up for at least eighteen months. At the end of follow-up, bilateral fusion mass was radiographically confirmed in 113 (62%) patients, unilateral fusion mass was observed in fifty-seven (31%) patients, and twelve (7%) patients exhibited no fusion mass at the arthrodesis level. The clinical outcome was rated excellent/good in 138 (76%) patients, fair in thirty-five (19%) and poor in nine (5%). Use of in situ local autografts yields satisfactory clinical results in instrumented posterolateral spinal fusion. No significant correlation was noted between the level of arthrodesis and the radiological outcome, nor between the level of arthrodesis and the clinical outcome. Radiographic evaluation of bony fusion mass was not predictive of the clinical findings.

The pain experience and future expectations of chronic low back pain patients following spinal fusion

AIM

In a sample of patients who underwent instrumented spinal fusions for chronic low back pain (CLBP), the purposes of this study were: to determine the amount of pain patients experienced and to determine the impact of length of time since surgery, use of pain medication and their outlook on the future on these pain intensity scores.

BACKGROUND

An increasing number of people report CLBP and one of the treatments is instrumented fusion.

METHOD

The study used a cross-sectional design. Visual analogue scales were used to measure pain intensity in different locations and a single item measured patients' view of the future. Data were collected in November 2001.

RESULTS

The sample consisted of 101 patients (71% women) aged 26-59 years treated with instrumented fusion 1-8 years ago. As many as 87% reported pain 1-8 years after the surgery. Most patients reported pain of low-to-moderate intensity in the neck and shoulders, back and hips, feet and legs and in total pain. As many as 45% of the patients did not take pain medication and patients using more analgesics reported more pain than those using fewer analgesics (p < 0.05). Patients with a more positive outlook on the future reported significantly less pain in all of the locations that were evaluated (p < 0.01).

CONCLUSION

A high percentage of patients with CLBP continue to experience pain 1-8 years after spinal fusion. A positive outlook towards the future seems to be associated with less pain in these patients. Relevance to clinical practice. Patients who continue to experience pain and have a more negative outlook on the future may benefit from psychoeducational interventions that teach them how to better cope with their pain.

Minimum four-year follow-up of spinal stenosis with degenerative spondylolisthesis treated with decompression and dynamic stabilization

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

To test whether posterior dynamic stabilization in situ with Dynesys (Zimmer Spine, Minneapolis, MN) can maintain enough stability to prevent progression of spondylolisthesis in long-term follow-up.

SUMMARY OF BACKGROUND DATA

In spinal stenosis with degenerative spondylolisthesis, decompression and fusion are widely recommended. However, drawbacks of fusion remain length of surgery, blood loss, possible adjacent segment disease, errant instrumentation, nonunion, and pain at the bone donor site. The Dynesys system was introduced to stabilize the spine without adding bone graft for fusion. Excellent 2 years results have been reported.

METHODS

Twenty-six consecutive patients (mean age, 71 years) with symptomatic lumbar spinal stenosis and degenerative spondylolisthesis underwent interlaminar decompression and stabilization with Dynesys. Patients were evaluated clinically and radiologically after a minimum follow-up of 4 years.

RESULTS

Nineteen of 26 patients could be evaluated with a mean follow-up of 52 months (range, 48-57 months). Pain on VAS and walking distance improved significantly (P < 0.001) at 2 years and remained unchanged at 4 years follow-up. Radiographically, spondylolisthesis did not progress and the motion segments remained stable, even in the 3 patients who showed slight screw-loosening at 2 and 4 years follow-up. One patient showed screw breakage with low back pain and motion at the instrumented level in flexion/extension views. At 4 years follow-up, 47% of the patients showed some degeneration at adjacent levels. Overall, patient satisfaction remained high as 95% would undergo the same procedure again.

CONCLUSION

In elderly patients with spinal stenosis and degenerative spondylolisthesis, decompression and dynamic stabilization lead to excellent clinical and radiologic results. It maintains enough stability to prevent progression of spondylolisthesis. Because no bone grafting is necessary, donor site morbidity, which is one of the main drawbacks of fusion is eliminated. However, the degenerative disease still is progressive and degeneration at adjacent motion segments remains a problem.

The safety and efficacy of OP-1 (rhBMP-7) as a replacement for iliac crest autograft for posterolateral lumbar arthrodesis: minimum 4-year follow-up of a pilot study

BACKGROUND CONTEXT

Although autogenous bone is still considered to be the gold standard graft material for promoting spinal fusion, other bone graft substitutes have been developed in an attempt to improve arthrodesis rates and avoid the complications associated with the procurement of autograft. The bone morphogenetic proteins (BMPs) represent a family of osteoinductive growth factors that are known to stimulate the osteoblastic differentiation of stem cells. Osteogenic protein-1 (OP-1) Putty is a commercially available BMP preparation that is already approved for use in humans. Previous clinical studies involving patients with degenerative spondylolisthesis have reported that the efficacy and safety of OP-1 Putty is comparable to that of autograft at both 1- and 2-year follow-up.

PURPOSE

The purpose of this study was to evaluate the intermediate-term efficacy and safety of OP-1 Putty as an alternative to autogenous bone by comparing the 4-year radiographic, clinical, and safety data of these same patients who underwent decompression and uninstrumented fusion with either OP-1 Putty or iliac crest autograft.

STUDY DESIGN/SETTING

A prospective, randomized, controlled, multicenter clinical pilot study.

PATIENT SAMPLE

Thirty-six patients undergoing decompressive laminectomy and single-level uninstrumented fusion for degenerative spondylolisthesis and symptomatic spinal stenosis were randomized in a 2:1 fashion to receive either OP-1 Putty (24 patients) or autogenous iliac crest bone graft (12 patients).

OUTCOME MEASURES

Patient-reported outcome measures consisting of Oswestry Disability Index and Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) scores were used to evaluate clinical efficacy. Perioperative data including operative time, estimated blood loss, and duration of hospital stay were also recorded for each surgery. Postoperatively, a neurological examination and an assessment of donor-site pain (if applicable) were performed at every follow-up visit. Radiographic fusion success was defined as the presence of continuous bridging bone formation between the transverse processes at the level of the spondylolisthesis with minimal motion evident on dynamic lateral x-ray films. The primary efficacy endpoint was the overall success rate, a composite measure derived from both radiographic and clinical parameters. The safety of OP-1 Putty was confirmed by comparing the nature and frequency of all adverse events and complications that were prospectively observed in either of the groups.

METHODS

Thirty-six patients with degenerative spondylolisthesis and symptoms of neurogenic claudication underwent decompressive laminectomy and single-level uninstrumented fusion with either OP-1 Putty or autograft. All patients were evaluated at 6 weeks and 3, 6, 9, 12, and 24 months, after which time they were instructed to return on a yearly basis. Multiple neuroradiologists blinded to the assigned treatment reviewed static and dynamic X-ray films with digital calipers to assess fusion status according to the presence of continuous bridging bone across the transverse processes as well as the amount of residual motion evident at the level of interest. Oswestry Disability Index surveys and SF-36 questionnaires were used to assess clinical outcomes.

RESULTS

At the 48-month time point, complete radiographic and clinical data were available for 22 of 36 patients (16 OP-1 Putty and 6 autograft) and 25 of 36 patients (18 OP-1 Putty and 7 autograft), respectively. Radiographic evidence of a solid arthrodesis was present in 11 of 16 OP-1 Putty patients (68.8%) and 3 of 6 autograft patients (50%). Clinically successful outcomes defined as at least a 20% improvement in preoperative Oswestry scores were experienced by 14 of 19 OP-1 Putty patients (73.7%) and 4 of 7 autograft patients (57.1%); these clinical findings were corroborated by similar increases in SF-36 scores. The respective overall success rates of the OP-1 Putty and autograft group were 62.5% and 33.3%. In this study, there were no incidents of local or systemic toxicity, ectopic bone production, or other adverse events directly related to the use of OP-1 Putty.

CONCLUSION

Despite the challenges associated with obtaining a solid uninstrumented fusion in patients with degenerative spondylolisthesis, the rates of radiographic fusion, clinical improvement, and overall success associated with the use of OP-1 Putty were at least comparable to that of the autograft controls for at least 48 months after surgery. These results appear to validate the short-term results previously reported for OP-1 Putty and suggest that this material may potentially represent a viable bone graft substitute for certain fusion applications.

Rates of perioperative complications associated with laminectomies in patients with achondroplasia

BACKGROUND

Lumbar decompressive surgery can be complicated by dural tears, infection, nerve root injury, deep venous thrombosis, and epidural hematoma. However, perioperative complications of multilevel laminectomies in patients with achondroplasia rarely are reported. Our objective was to determine the perioperative complication rates associated with laminectomies in patients with achondroplasia.

METHODS

We reviewed the medical records of the initial laminectomies for all ninety-eight patients with achondroplasia at our institution, which included twenty-eight patients who had had previous spine surgeries at other institutions, and determined the rates of complications in the following categories: neurologic, pulmonary, cardiovascular, and gastrointestinal complications; intraoperative dural tears; infections at the incision site; and mortality.

RESULTS

Sixty (61%) of ninety-eight patients had at least one perioperative complication. By category, these included intraoperative dural tears, which occurred in 37% (thirty-six patients); neurologic complications, in 23% (twenty-three patients); infections at the incision site, in 9% (nine patients); deep venous thrombosis, in 3% (three patients); pulmonary complications, in 3% (three patients); and gastrointestinal complications, in 3% (three patients). The only death was caused by a pulmonary embolism.

CONCLUSIONS

Perioperative complications are common in patients with achondroplasia undergoing multilevel laminectomies, and the perioperative care team should be aware of these complications when caring for these patients.

Soft stabilization with an artificial intervertebral ligament in grade I degenerative spondylolisthesis: comparison with instrumented posterior lumbar interbody fusion

BACKGROUND

The purpose of this retrospective study was to evaluate the efficacy of soft stabilization with an artificial intervertebral ligament after microdecompression for the treatment of grade I degenerative spondylolisthesis.

METHODS

From a total of 54 patients with degenerative spondylolisthesis who were treated surgically from May 2000 to April 2003, 36 patients who showed grade I spondylolisthesis without evidence of concomitant disc herniation necessitating discectomy were enrolled in the study. After decompression, the patients had undergone either soft stabilization with an artificial intervertebral ligament (n = 17) or instrumented posterior lumbar interbody fusion (PLIF; n = 19).

RESULTS

The average follow-up period was 24 months for the PLIF group and 16 months for the soft stabilization group. In the PLIF group, preoperative mean scores of 60% on the Oswestry Disability Index, 8.8 on the visual analog scale (VAS) for low-back pain, and 9.3 on the VAS for leg pain improved to 28%, 4.1, and 2.6, respectively, after surgery. Corresponding scores in the soft stabilization group were 55%, 8.4, and 8.9, improving to 25%, 4.1, and 2.2 after surgery. There were no significant differences between the 2 groups in any of these clinical parameters. Patients' subjective improvement rates and satisfaction with the surgical procedure were higher in the soft stabilization group, but the differences were not significant. Mean operation time and mean blood loss were significantly lower in the soft stabilization group than in the PLIF group. In the soft stabilization group, there were 3 cases of progression of slippage in patients who had had preoperative slippage of more than 20%; there was 1 dural tear in the PLIF group.

CONCLUSIONS

Patients with grade I degenerative spondylolisthesis who received soft stabilization with an artificial intervertebral ligament after microdecompression had clinical outcomes similar to those of patients who received PLIF. Since soft stabilization can be done in a much less invasive way than fusion, if slippage is 20% or less, soft stabilization with an artificial ligament is a viable alternative to fusion for patients who are elderly or who have significant comorbidities that make a prolonged operation inadvisable.

LEVEL OF EVIDENCE

This study was a retrospective comparative study with a very limited population (level III evidence).

Self-report outcome measures for low back pain: searching for international cross-cultural adaptations

STUDY DESIGN

Systematic review.

OBJECTIVES

To describe the available cross-cultural adaptations of low back pain (LBP) self-report outcome measures and the psychometric testing that has occurred for each adaptation.

SUMMARY OF BACKGROUND DATA

Self-report measures are commonly used in clinical practice and in research studies. Most existing questionnaires were developed in English, and it is not clear how many have been adapted to other languages.

METHODS

Two different searches on MEDLINE, EMBASE, CINAHL, and LILACS were performed. The first search identified questionnaires specifically designed for patients with LBP. The second search combined the name of the questionnaire with 35 different languages in order to locate cross-cultural adaptations of the questionnaire. Data on the psychometric testing of the translated questionnaires were extracted.

RESULTS

Forty questionnaires were identified, only 15 of which had been adapted to a new language. Only 19 of the 35 different languages we searched for were represented in the search results. From 1400 possible adaptations, only 61 have been completed. Psychometric testing of the adapted questionnaires was quite variable and in general suboptimal with testing usually restricted to an assessment of reliability and construct validity.

CONCLUSIONS

There is a clear need for further cross-cultural adaptation of LBP self-report measures and for greater attention to the quality of psychometric evaluation of adapted questionnaires. Without appropriately adapted measures, the clinical management of LBP patients who do not speak English is potentially compromised.

Outcomes for patients with chronic low back pain treated using instrumented fusion

The aim of this study was to describe the pain experience at 1-8 years follow-up of patients who were treated with instrumented fusion because of chronic low back pain, and to evaluate the impact of demographic- and disease-specific variables on pain. The sample comprised 101 of 126 Norwegian patients (response rate 80%), aged 25-60 years (mean 46 years) who were treated in a Swedish hospital between 1993 and 2000. The visual analogue scale and Norwegian Pain Questionnaire were used to evaluate pain. Independent t-tests, anova, correlation and multiple linear regression analyses were performed. Sixteen per cent of patients reported no pain, 17% mild pain, 29% moderate pain and 38% strong to excruciating pain following treatment using instrumented fusion. Demographic- and disease-specific variables explained 29% of the variance in back and hip pain intensities, and 19%, 30%, 6% and 23% of the sensory, affective, evaluative and total pain experience, respectively. Patients who needed to use pain-killing reported more pain than those who did not (p < 0.001). Patients suffering from other chronic conditions also reported more affective pain (p < 0.001). In conclusion, at 1-8 years follow up after instrumented fusion most of the patients suffered from moderate pain or less. Further, amount of pain-killing and comorbidity conditions seemed to be highly related to pain in patients treated with instrumented fusion.

Relationships between demographic, clinical and pain variables and health-related quality of life in patients with chronic low back pain treated with instrumented fusion

The purpose of this cross-sectional study was to assess the relationships between demographic, clinical and pain variables and health-related quality of life (HRQOL) in patients who had undergone instrumented spinal fusion because of chronic low back pain (CLBP). The sample comprises 101 patients (70% women, mean age 46 years) who had received surgery between 1993 and 2000. The SF-36 Health Survey was used to assess HRQOL. Pain was assessed by sensory, affective and evaluative subgroups of the Norwegian Pain Questionnaire (modified McGill Pain Questionnaire). Age, work status, number of years after surgery, physical training, other chronic conditions and affective and evaluative pain (all p < 0.05) were the most prominent factors affecting HRQOL. The highest adjusted R(2) to explain the variance was physical function (52%) and the lowest was emotional role limitations (15%). Pain, particularly affective and evaluative pain, contributed more to the explained variance of HRQOL than demographic and clinical variables.

Posterolateral lumbar spinal fusion with autogenous bone chips from laminectomy extended with OsteoSet

BACKGROUND

This study was conducted to evaluate posterolateral lumbar fusion with autogenous corticocancellous bone chips from the laminae and spinous processes extended with OsteoSet instead of cancellous bone from the iliac crest.

METHODS

A total of 124 patients who underwent posterior decompression and posterolateral fusion with instrumentation between May 2001 and December 2003 were analyzed retrospectively. The study population comprised 49 males and 75 females with a mean age of 66 +/- 9.5 years. In all the patients, corticocancellous bone chips from laminectomy and OsteoSet were used as the graft material. There was no cancellous bone harvested from the iliac crest. The follow-up period was 28 +/- 7.1 months.

RESULTS

The overall union rate was 91%, and the average union time was 3.9 months. There were 3 complications, including 2 patients with dura tear, and 1 with deep infection. At the final follow-up, the good and excellent results were up to 83.9%.

CONCLUSION

Graft material from laminae and spinous processes extended with OsteoSet is reliable and effective enough to replace the graft from the posterior iliac crest.

Use of Recombinant Human Bone Morphogenetic Protein-2 as an Adjunct in Posterolateral Lumbar Spine Fusion

INTRODUCTION

This study determines whether recombinant human bone morphogenetic protein-2 (rhBMP-2) (12 mg at the rate of 1.5 mg/mL) delivered on an absorbable collagen sponge with an added bulking agent can increase posterolateral lumbar spine fusion success rates and decrease time for fusion with autogenous bone grafts.

METHOD

A prospective, single institution, clinical case-matched, radiographic, cohort study was undertaken. A total of 52 patients underwent posterolateral lumbar arthrodesis with pedicle screw instrumentation. The experimental group (n=41) underwent placement of Iliac crest bone graft (ICBG) with InFUSE (12 mg/level at the rate of 1.5 mg/mL). The control group (n=11) consisted of sex-matched patients, consecutively collected over the same time period with an instrumented posterolateral arthrodesis and ICBG placed in the intertransverse space.

OUTCOME MEASURES

Thin-cut (2 mm) axial, coronal, and sagittal reconstructions were blindly evaluated for evidence of bridging bone and cortication of the fusion mass by 3 separate reviewers. Fusions were graded and an overall score was given to the quality of the fusion mass.

RESULTS

Fifty patients (ICBG alone n=11; ICBG/rhBMP-2 n=39) were available for CT evaluation at 2-year follow-up. An overall 97% (68/70 levels; Definite+Probably Fused) fusion rate in the rhBMP-2 group was achieved as compared to the 77% fusion rate (17/22 levels) in the ICBG alone group (P<0.05). In the rhBMP-2 group, 92% of the patients (36/39 patients) received an overall excellent subjective fusion rating as compared to 27% (3/11) in the control group (P<0.05). There was no computed tomographic evidence of soft-tissue ossification, dural ossification, or laminar bone regrowth in any patient.

CONCLUSIONS

The adjunctive use of rhBMP-2 and ICBG seems to be safe and results in significantly larger and more consistent posterolateral fusion masses.

Dynamic stabilization in addition to decompression for lumbar spinal stenosis with degenerative spondylolisthesis

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

To test whether elastic stabilization with the Dynesys system (Zimmer Spine, Minneapolis, MN) provides enough stability to prevent further progression of spondylolisthesis as well as instability after decompression for spinal stenosis with degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

In spinal stenosis with degenerative spondylolisthesis, decompression and fusion is widely recommended. However, patients have donor site pain. In 1994, a dynamic transpedicular system (Dynesys) was introduced to the market, stating that stabilization is possible without bone grafting.

METHODS

A total of 26 patients (mean age 71 years) with lumbar spinal stenosis and degenerative spondylolisthesis underwent interlaminar decompression and dynamic stabilization with the Dynesys system. Minimum follow-up was 2 years. Operative data, clinical outcome, and plain and flexion/extension radiographs were obtained and compared to preoperative and postoperative data.

RESULTS

Mean leg pain decreased significantly (P < 0.01), and mean walking distance improved significantly to more than 1000 m (P < 0.01). There were 5 patients (21%) who still had some claudication. A total of 21 patients (87.5%) would undergo the same procedure again. Radiographically, no significant progression of spondylolisthesis could be detected. The implant failure rate was 17%, and none of them were clinically symptomatic.

CONCLUSIONS

In elderly patients with spinal stenosis with degenerative spondylolisthesis, dynamic stabilization with the Dynesys system in addition to decompression leads to similar clinical results as seen in established protocols using decompression and fusion with pedicle screws. It maintains enough stability to prevent further progression of spondylolisthesis or instability. With the Dynesys system, no bone grafting is necessary, therefore, donor site morbidity can be avoided.

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 9: fusion in patients with stenosis and spondylolisthesis

The best medical evidence available in the literature confirms the utility of fusion for improving patient outcomes following decompression for stenosis associated with spondylolisthesis. The majority of evidence from other studies comparing outcomes after decompression alone or decompression combined with PLF in patients with stenosis and spondylolisthesis also favors the performance of PLF. The medical evidence regarding the use of pedicle screw fixation in this patient population is rated as Class III and is inconsistent. A consistent benefit associated with the use of pedicle screw fixation has been reported in patients with preoperative instability or kyphosis. Iatrogenic instability following decompression is associated with poor outcomes and may also be treated with PLF involving supplemental instrumentation. The precise definition of instability or kyphosis has varied among researchers and requires further study.

Lower dose of rhBMP-2 achieves spine fusion when combined with an osteoconductive bulking agent in non-human primates

STUDY DESIGN

A non-human primate lumbar intertransverse process arthrodesis model was used to evaluate the effectiveness of different formulations of recombinant human bone morphogenetic protein-2 (rhBMP-2) to induce consistent bone formation.

OBJECTIVE

To determine if the combination of rhBMP-2/absorbable collagen sponge (ACS) wrapped around a bulking agent, consisting of a biphasic calcium phosphate/collagen composite, could achieve posterolateral spine fusion with a dose of rhBMP-2 (3.0 mg/side) that previously failed to induce posterolateral fusion in rhesus monkeys with other carriers.

SUMMARY OF BACKGROUND DATA

Successful bone induction in both human and non-human primates has required higher concentrations of BMP than were required in lower order models. The Food and Drug Administration approved concentration of rhBMP-2 for interbody fusion (1.5 mg/mL) when delivered on the ACS alone without a bulking agent (doses 3-9 mg/side) has failed to induce clinically relevant amounts of bone formation in a posterolateral spine fusion model in rhesus monkeys. Previously, a higher concentration of 2.0 mg/mL of rhBMP-2 delivered on stacked sheets of a biphasic calcium phosphate ceramic/collagen compression resistant matrix (CRM) was required to achieve fusion in the rhesus monkey and was the basis for this study (doses of 6-12 mg/side).

METHODS

Nine skeletally mature, rhesus macaque monkeys underwent single level posterolateral arthrodesis at L4-L5. Two different rhBMP-2 doses were evaluated in 3 delivery configurations. The first 3 monkeys received 10 mg/side (2.5 mL at 4.0 mg/mL) of rhBMP-2 loadeddirectly onto a CRM carrier (15% hydroxyapatite/85%beta-tricalcium phosphate ceramic/collagen matrix), resulting in a final concentration of 2.0 mg/mL. The second 3 monkeys received 3 mg/side (2.0 mL at 1.5 mg/mL) of rhBMP-2 loaded directly on the CRM carrier, resulting in a 0.6 mg/mL final concentration. Three additional monkeys also received the 3 mg/side (2.0 mL at 1.5 mg/mL) of rhBMP-2 delivered on an ACS, which was then wrapped around the dry CRM matrix used as a bulking agent, yielding a 1.5 mg/mL final concentration of rhBMP-2 on the sponge wrapped around the bulking agent. The monkeys were euthanized at 24 weeks after surgery. Manual palpation, plain radiographs, computerized tomography, and nondecalcified histology were used to evaluate fusion in a blinded fashion.

RESULTS

The 3 monkeys with 10 mg rhBMP-2 placed directly on the CRM carrier (2.0 mg/mL final concentration) achieved solid fusion. The 3 monkeys that underwent fusion with 3 mg of rhBMP-2 placed directly on the CRM carrier (0.6 mg/mL final concentration) failed to achieve fusion. In contrast, the 3 monkeys that underwent fusion with the same 3 mg dose of rhBMP-2 dispensed only on an ACS that was wrapped around the CRM achieved solid bilateral fusion.

CONCLUSIONS

This study shows the importance of carrier optimization and final implant protein concentration for the successful delivery of rhBMP-2. By combining the properties of the ACS with the CRM, the required dosage of rhBMP-2 was diminished by more than 3-fold in the non-human primate model. This finding suggests that the currently available concentration of rhBMP-2 (1.5 mg/mL) could be successful for achieving posterolateral spine fusion when combined with an osteoconductive bulking agent that can support the induced new bone formation.

Predictors of outcomes after posterior decompression and fusion in degenerative spondylolisthesis

No consensus has been reached regarding surgical management of degenerative spondylolisthesis. The optimal type of surgical procedure and surgical indications have not been precisely defined. In order to screen for predictors of outcome, we retrospectively studied patient outcomes after posterior decompression and fusion for isolated lumbar degenerative spondylolisthesis. Twenty-four consecutive patients (age range 50-78 years) underwent primary surgery for isolated lumbar degenerative spondylolisthesis. The surgical procedure consisted of posterior decompression and pedicle screw instrumented fusion using autogeneous bone graft, with or without interbody fusion. Clinical and radiologic status were assessed using the Beaujon functional score and plain AP and lateral radiographs. A multivariate analysis was used to correlate the functional score increase with surgical procedure modifications and preoperative clinical and radiologic features in order to determine which of them led to better results. Eighteen patients completed the evaluation. Six others were lost to follow-up after a minimum of 0.87 years. Combining all the results, the mean follow-up was 2.87 years. The Beaujon score was improved in the 24 patients (P<0.001), and fusion was successful in all cases. Additional interbody fusion and preoperative leg pain were significantly correlated with larger score increase (P=0.016 and P=0.003). Posterior decompression and fusion is successful in treating lumbar degenerative spondylolisthesis. From this study, circumferential fusion improves the outcomes and leg pain is a fair indication for surgery.

A 2-year follow-up pilot study evaluating the safety and efficacy of op-1 putty (rhbmp-7) as an adjunct to iliac crest autograft in posterolateral lumbar fusions

The ability of bone morphogenetic proteins (BMPs) to induce bone formation has led to a multitude of investigations into their use as bone graft substitutes in spinal surgery. The purpose of this multi-center clinical pilot study was to evaluate the safety and efficacy of BMP-7 (osteogenic protein 1, OP-1), in the form of a putty, combined with autograft for intertransverse process fusion of the lumbar spine in patients with symptomatic spinal stenosis and degenerative spondylolisthesis following spinal decompression. Twelve patients with spinal stenosis and degenerative lumbar spondylolisthesis underwent a laminectomy and partial or complete medial facetectomy as required for decompression of the neural elements, followed by an intertransverse process fusion by placing iliac crest autograft and OP-1 putty between the decorticated transverse processes. No instrumentation was used. Patients were followed clinically using the Oswestry scale and SF-36 outcome forms, and radiographically using static and dynamic radiographs to assess their fusion status over a 2-year period. Independent and blinded radiologists assessed the films for the presence of bridging bone between the transverse processes and measured translation and angulation on dynamic films using digital calipers. Radiographic outcome was compared to a historical control (autograft alone fusion without instrumentation for the treatment of degenerative spondylolisthesis). All adverse events were recorded prospectively. The results showed eight of the nine evaluable patients (89%) obtained at least a 20% improvement in their preoperative Oswestry score, while five of ten patients (50%) with radiographic follow-up achieved a solid fusion by the criteria used in this study. Bridging bone on the anteroposterior film was observed in seven of the ten patients (70%). No systemic toxicity, ectopic bone formation, recurrent stenosis or other adverse events related to the OP-1 putty implant were observed. A successful fusion was observed in slightly over half the patients in this study, using stringent criteria without adjunctive spinal instrumentation. This study did not demonstrate the statistical superiority of OP-1 combined with autograft over an autograft alone historical control, in which the fusion rate was 45%. There were no adverse events related to the OP-1 putty implant in this study, which supports findings in other studies suggesting the safety of bone morphogenetic proteins in spinal surgery.

A pilot study evaluating the safety and efficacy of OP-1 Putty (rhBMP-7) as a replacement for iliac crest autograft in posterolateral lumbar arthrodesis for degenerative spondylolisthesis

STUDY DESIGN

A prospective, randomized, controlled, multicenter clinical study was conducted.

OBJECTIVE

To compare the clinical and radiographic outcomes of patients treated with OP-1 (BMP-7) Putty to autogenous iliac crest bone graft for one-level uninstrumented posterolateral fusion of the lumbar spine following decompressive laminectomy for the treatment of symptomatic degenerative spondylolisthesis with spinal stenosis.

BACKGROUND

Preclinical studies have demonstrated that osteoinductive recombinant human osteogenic protein 1 in the form of OP-1 Putty is successful at achieving a posterolateral fusion in rabbits and dogs without any significant safety concerns.

METHODS

Thirty-six patients with degenerative lumbar spondylolisthesis and symptoms of neurogenic claudication were randomized (2:1) to either OP-1 Putty (3.5 mg of OP-1 per side) or autogenous iliac crest bone graft for one-level uninstrumented posterolateral fusion following a decompressive laminectomy. Enrollment in the study was complete when 24 OP-1 Putty patients and 12 autograft patients had been randomized and treated. A patient administered Oswestry scale and SF-36 scale were used to determine clinical outcomes. Independent, blinded neuroradiologists reviewed both static and dynamic radiographs to determine fusion status.

RESULTS

At the 1-year follow-up, 32 patients were available for clinical analysis and 29 patients were available for radiographic review. Clinical success as measured on the Oswestry scale was achieved by 18 of 21 (86%) OP-1 Putty patients and 8 of 11 (73%) autograft patients. SF-36 pain index scores showed similar results. Fourteen of 19 (74%) OP-1 Putty patients and 6 of 10 (60%) autograft patients achieved a successful posterolateral fusion fulfilling all fusion criteria. Of the 29 evaluable patients, 15 were both clinical and radiographic successes, 5 were radiographic successes but were clinical failures, 1 patient was both a radiographic and clinical failure, and 8 patients were radiographic failures but were clinical successes. No systemic toxicity, ectopic bone formation, recurrent stenosis, or other adverse events related to the OP-1 Putty implant were observed.

CONCLUSION

Although the posterolateral spine is a challenging fusion environment in patients with degenerative spondylolisthesis, successful radiographic fusion was obtained using OP-1 Putty at a rate that was similar to autograft given the number of patients in this study. Importantly, there were no apparent adverse consequences related to the use of the OP-1 Putty implant in this patient population.

Ne-Osteo bone growth factor for posterolateral lumbar spine fusion: results from a nonhuman primate study and a prospective human clinical pilot study

STUDY DESIGN

Prospective animal and human clinical pilot trial.

OBJECTIVES

The purpose of this study was to determine and test the dose of Ne-Osteo growth factor extract and carrier required for consistent radiographic bone induction in humans.

SUMMARY OF BACKGROUND DATA

Preclinical studies have demonstrated that Ne-Osteo, an extract-containing bone morphogenetic proteins, was successful at generating spine fusion in rabbits and rhesus monkeys. Consistent fusions have yet to be achieved in nonhuman primates and humans.

METHODS

Adult rhesus monkeys underwent single-level posterolateral intertransverse lumbar arthrodesis with either 3.0 mg (N = 4), 5.0 mg (N = 4), 12.5 mg (N = 4), or 25 mg (N = 4) of Ne-Osteo per side. Animals were killed after 24 weeks. In the human clinical trial, 22 patients (18 females, 4 males) had lumbar spinal stenosis and/or spondylolisthesis requiring spine arthrodesis. To minimize patient risk of nonunion, patients received autogenous bone graft from the posterior iliac crest on one side and Ne-Osteo growth factor on the other. The dose was 12.5 mg, 25 or 50 mg, or 25 mg Ne-Osteo per side performed in the three phases, respectively.

RESULTS

Three of four monkeys that received 12.5 mg Ne-Osteo per side and four of four that received 25 mg per side achieved solid fusions. In phase I of the human clinical trial, two of six patients showed radiographic bone induction (plain radiograph, CT scans-blindly evaluated) on the Ne-Osteo side (12.5-mg dose). In phase II, both sides were graded as fused in five of six patients. Although graded as fused, the 6-month scans demonstrated a ring of new bone with the center filling in slower (12-24 mo) than was predicted by nonhuman primate studies. As a result, phase III carrier was designed to have a more porous/open early fusion mass than with the dense DBM paste (used in phase I and II) by mixing in local bone or cancellous allograft chips. Results using the 25- and 50-mg doses were the same, so 25 mg was used in phase III. In phase III, 9 of 10 autograft were fused by 12 months. Five of five patients with Ne-Osteo plus local bone and four of five with allograft chips were fused by 6 months. The one patient in this group that did not heal on either the autograft or the Ne-Osteo side was a smoker.

CONCLUSIONS

A graft composite of Ne-Osteo bone growth factor with human DBM with or without cancellous allograft or local bone autograft was capable of achieving a contiguous spine fusion mass in 15 of 16 patients at a dose of at least 25 mg per side. This result was comparable with the results using iliac crest autograft (94%) in this side-by-side model. These results warrant confirmation in a definitive trial using Ne-Osteo on both sides of the spine and thus avoiding the need for iliac crest bone graft harvest.