Biomechanical comparison of facet-sparing laminectomy and Christmas tree laminectomy

Effectiveness of a Decision-Making Protocol for the Surgical Treatment of Lumbar Stenosis with Grade 1 Degenerative Spondylolisthesis

BACKGROUND

Addition of fusion to decompression for stenosis with grade 1 degenerative spondylolisthesis is a controversial topic, and the question remains if fusion provides any benefit to the patient that warrants the increased health care utilization and perioperative morbidity. There is no consensus on indications for use of fusion over decompression alone.

METHODS

Patients received fusion or decompression according to a decision-making protocol based on their pattern of complaints, location of the compression, and facet angles and effusion as proven predictors of postoperative instability. Propensity score matching of patients was done for baseline data.

RESULTS

The study comprised 102 patients in 2 equally sized groups. No intergroup differences in numeric rating scale and Oswestry Disability Index were detected at any follow-up point (all P > 0.05). Duration of surgery, length of stay, estimated blood loss, and radiation doses were higher in the fusion group (all P < 0.001). Cumulative reoperation rate was similar with 6% for fusion and 8% for decompression (P > 0.05), as was the complication rate (8% vs. 6%, P > 0.05). Postoperative iatrogenic progression of spondylolisthesis requiring fusion surgery was seen in only 2% in the decompression group.

CONCLUSIONS

Use of a decision-making protocol led to a low rate of iatrogenically increased spondylolisthesis after decompression, while retaining outcomes. These data suggest that a decision-making protocol based on clinical history, location of nerve root compression, and proven radiologic predictors of postoperative instability assigns patients to fusion or decompression in a safe and effective manner.

Outcome after Surgery of Lumbar Spinal Stenosis: A Randomized Comparison of Bilateral Laminotomy, Trumpet Laminectomy, and Conventional Laminectomy

Background

Laminectomy is the traditional operating method for the decompression of spinal canal stenosis. New partial decompression processes have been suggested in the treatment of lumbar stenosis. The benefit of a micro surgical approach is the chance of an extensive bilateral decompression of the spinal canal or foramen at one or numerous levels, through a minimal para-spinal muscular separation.

Purpose

To match the safety and the clinical consequences after a bilateral laminotomy, laminectomy and trumpet laminectomy in patients with lumbar spinal stenosis who were randomized to one of three treatment groups.

Study design

Prospective study.

Methods

One hundred twenty consecutive patients with 227 levels of lumbar stenosis without significant herniated discs or instability were randomized to three treatment groups [bilateral laminotomy (Group 1), laminectomy (Group 2), and trumpet laminectomy (Group 3)]. Perioperative parameters and complications were documented. Symptoms and scores, such as a visual analog scale (VAS), Oswestry Disability Index, and patient satisfaction, were assessed preoperatively at 3, 6, and 12 months after surgery. Adequate decompression was achieved in all patients on the basis of surgeon satisfaction.

Results

The global complication rate was lowest in patients who had undertaken bilateral laminotomy (Group 1). The minimum follow-up of 12 months was achieved in 100% of patients. Matched with that experience in Group 1, but, with more remaining back and leg pain was found in Group 2, 3.85 ± 0.28 and 1.60 ± 0.44, respectively and 3.24 ± 0.22 and 2.44 ± 0.26 in Group 3, respectively compared with 1.84 ± 0.28 and 1.25 ± 0.12 (Group 1) at the 1-year follow-up assessment (p < 0.05). It was the same for the ODI scores, which reached 14 ± 8% (Group 1), 28 ± 12% (Group 2), and 26 ± 16 after 12 months of surgery (Group 3) (significant, p < 0.01 compared with preoperative scores). Patient satisfaction was higher in Group 1, with 7.5, 20, and 25% of patients displeased (in Groups 1, 2, and 3, respectively; p < 0.01).

Conclusion

Bilateral Laminotomy is certified acceptable and harmless in decompression of lumbar stenosis, causing a highly significant decrease of symptoms and disability.

The effects of single-level instrumented lumbar laminectomy on adjacent spinal biomechanics

Study Design Biomechanical study. Objective Posterior instrumentation is used to stabilize the spine after a lumbar laminectomy. However, the effects on the adjacent segmental stability are unknown. Therefore, we studied the range of motion (ROM) and stiffness of treated lumbar spinal segments and cranial segments after a laminectomy and after posterior instrumentation in flexion and extension (FE), lateral bending (LB), and axial rotation (AR). These outcomes might help to better understand adjacent segment disease (ASD), which is reported cranial to the level on which posterior instrumentation is applied. Methods We obtained 12 cadaveric human lumbar spines. Spines were axially loaded with 250 N for 1 hour. Thereafter, 10 consecutive load cycles (4 Nm) were applied in FE, LB, and AR. Subsequently, a laminectomy was performed either at L2 or at L4. Thereafter, load-deformation tests were repeated, after similar preloading. Finally, posterior instrumentation was added to the level treated with a laminectomy before testing was repeated. The ROM and stiffness of the treated, the cranial adjacent, and the control segments were calculated from the load-displacement data. Repeated-measures analyses of variance used the spinal level as the between-subject factor and a laminectomy or instrumentation as the within-subject factors. Results After the laminectomy, the ROM increased (+19.4%) and the stiffness decreased (-18.0%) in AR. The ROM in AR of the adjacent segments also increased (+11.0%). The ROM of treated segments after instrumentation decreased in FE (-74.3%), LB (-71.6%), and AR (-59.8%). In the adjacent segments after instrumentation, only the ROM in LB was changed (-12.9%). Conclusions The present findings do not substantiate a biomechanical pathway toward or explanation for ASD.

Results of cervical recapping laminoplasty: gross anatomical changes, biomechanical evaluation at different time points and degrees of level involvement

Background

Recapping laminoplasty has become the frequently-used approach to the spinal canal when bone decompression of the vertebral canal is not the goal. However, what changes will occur after surgery, and whether recapping laminoplasty can actually reduce the risk of delayed deformities remains unknown.

Methodology

We designed an animal experiment using a caprine model, and partitioned the animals into in vitro and in vivo surgical groups. We performed recapping laminoplasty on one group and laminectomy on another group. These animals were sacrificed six months after operating, cervical spines removed, biomechanically tested, and these data were compared to determine whether the recapping laminoplasty technique leads to subsequent differences in range of motion. Image data were also obtained before the surgery and when the animals were killed. Besides, we investigated the initial differences in kinetics between recapping laminoplasty and laminectomy. We did this by comparing data obtained from biomechanical testing of in vitro-performed recapping laminoplasty and laminectomy. Finally, we investigated the effect that longitudinal distance has on cervical mechanics. This was determined by performing a two-level recapping laminoplasty, and then extending the laminoplasty to the next level and repeating the mechanical testing at each step.

Principal Findings

There were three mainly morphological changes at the six months after laminoplasty: volume reduction and bone nonunion of the recapping laminae, irregular fibrosis formation around the facet joints and re-implanted lamina-ligamentous complex. In the biomechanical test, comparing with laminectomy, recapping laminoplasty didn’t show significant differences in the immediate postoperative comparison, while recapping laminoplasty demonstrated significantly decreased motion in flexion/extension six months later. Inclusion of additional levels in the laminotomy procedure didn’t lead to changes in immediate biomechanics.

Conclusions

Recapping laminoplasty can’t fully restore the posterior structure, but still reduced the risk of delayed cervical instability in a caprine model.

Five-year outcome of surgical decompression of the lumbar spine without fusion

As the average life expectancy of the population increases, surgical decompression of the lumbar spine is being performed with increasing frequency. It now constitutes the most common type of lumbar spinal surgery in older patients. The present prospective study examined the 5-year outcome of lumbar decompression surgery without fusion. The group comprised 159 patients undergoing decompression for degenerative spinal disorders who had been participants in a randomised controlled trial of post-operative rehabilitation that had shown no between-group differences at 2 years. Leg pain and back pain intensity (0-10 graphic rating scale), self-rated disability (Roland Morris), global outcome of surgery (5-point Likert scale) and re-operation rates were assessed 5 years post-operatively. Ten patients had died before the 5-year follow-up. Of the remaining 149 patients, 143 returned a 5-year follow-up (FU) questionnaire (effective return rate excluding deaths, 96%). Their mean age was 64 (SD 11) years and 92/143 (64%) were men. In the 5-year follow-up period, 34/143 patients (24%) underwent re-operation (17 further decompressions, 17 fusions and 1 intradural drainage/debridement). In patients who were not re-operated, leg pain decreased significantly (p < 0.05) from before surgery to 2 months FU, after which there was no significant change up to 5 years. Low back pain also decreased significantly by 2 months FU, but then showed a slight, but significant (p < 0.05), gradual increase of <1 point by 5-year FU. Disability decreased significantly from pre-operative to 2 months FU and showed a further significant decrease at 5 months FU. Thereafter, it remained stable up to the 5-year FU. Pain and disability scores recorded after 5 years showed a significant correlation with those at earlier follow-ups (r = 0.53-0.82; p < 0.05). Patients who were re-operated at some stage over the 5-year period showed significantly worse final outcomes for leg pain and disability (p < 0.05). In conclusion, pain and disability showed minimal change in the 5-year period after surgery, but the re-operation rate was relatively high. Re-operation resulted in worse final outcomes in terms of leg pain and disability. At the 5-year follow-up, the "average" patient experienced frequent, but relatively low levels of, pain and moderate disability. This knowledge on the long-term outcome should be incorporated into the pre-operative patient information process.

Biomechanical assessment of anterior lumbar interbody fusion with an anterior lumbosacral fixation screw-plate: comparison to stand-alone anterior lumbar interbody fusion and anterior lumbar interbody fusion with pedicle screws in an unstable human cadaver model

STUDY DESIGN

Human lumbosacral cadaveric specimens were tested in an in vitro biomechanical flexibility experiment using physiologic loads in 5 sequential conditions.

OBJECTIVE

To determine the biomechanical differences between anterior lumbar interbody fusion (ALIF) using cylindrical threaded cages alone or supplemented with an anterior screw-plate or posterior pedicle screws-rods.

SUMMARY OF BACKGROUND DATA

Clinically and biomechanically, stand-alone ALIF performs modestly in immobilizing the unstable spine. Pedicle screws improve fixation stiffness significantly, but supplementary anterior instrumentation has not been studied.

METHODS

There were 7 specimens tested: (1) intact, (2) after discectomy and facetectomy to induce moderate rotational and translational hypermobility, (3) with 2 parallel ALIF cages, (4) with cages plus a triangular anterior screw-plate, and (5) with cages plus pedicle screws-rods. Pure moments without preload induced flexion, extension, lateral bending, and axial rotation; linear shear forces induced anteroposterior translation. Angular and linear motions were measured stereophotogrammetrically, and range of motion (ROM) and stiffness were quantified.

RESULTS

Compared to the destabilized spine, interbody cages alone reduced ROM by 77% during flexion, 53% during extension, 60% during lateral bending, 69% during axial rotation, and 71% during anteroposterior shear (P < 0.001, analysis of variance/Fisher least significant difference). Addition of an anterior plate or pedicle screws-rods, respectively, further reduced ROM by 8% or 13% during flexion (P = 0.21), 21% or 28% during extension (P = 0.15), 5% or 25% during lateral bending (P = 0.04), 11% or 18% during axial rotation (P = 0.13), and 18% or 18% during anteroposterior shear (P = 0.17). Compared to stand-alone ALIF, both the anterior screw-plate and pedicle screw-rod fixation reduced vertebral ROM to less than 1.2 degrees of rotation and less than 0.1 mm of translation.

CONCLUSIONS

The anterior screw-plate and pedicle screws-rods both substantially reduced ROM and increased stiffness compared to stand-alone interbody cages. There was no significant difference in the amount by which the supplementary fixation devices limited flexion, extension, axial rotation, or anteroposterior shear; pedicle screws-rods better restricted lateral bending.

Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy

OBJECT

Recently, limited decompression procedures have been proposed in the treatment of lumbar stenosis. The authors undertook a prospective study to compare the safety and outcome of unilateral and bilateral laminotomy with laminectomy.

METHODS

One hundred twenty consecutive patients with 207 levels of lumbar stenosis without herniated discs or instability were randomized to three treatment groups (bilateral laminotomy [Group 1], unilateral laminotomy [Group 2], and laminectomy [Group 3]). Perioperative parameters and complications were documented. Symptoms and scores, such as visual analog scale (VAS), Roland-Morris Scale, Short Form-36 (SF-36), and patient satisfaction were assessed preoperatively and at 3, 6, and 12 months after surgery. Adequate decompression was achieved in all patients. The overall complication rate was lowest in patients who had undergone bilateral laminotomy (Group 1). The minimum follow up of 12 months was obtained in 94% of patients. Residual pain was lowest in Group 1 (VAS score 2.3 +/- 2.4 and 4 +/- 1 in Group 3; p < 0.05 and 3.6 +/- 2.7 in Group 2; p < 0.05). The Roland-Morris Scale score improved from 17 +/- 4.3 before surgery to 8.1 +/- 7, 8.5 +/- 7.3, and 10.9 +/- 7.5 (Groups 1-3, respectively; p < 0.001 compared with preoperative) corresponding to a dramatic increase in walking distance. Examination of SF-36 scores demonstrated marked improvement, most pronounced in Group 1. The number of repeated operations did not differ among groups. Patient satisfaction was significantly superior in Group 1, with 3, 27, and 26% of patients unsatisfied (in Groups 1, 2, and 3, respectively; p < 0.01).

CONCLUSIONS

Bilateral and unilateral laminotomy allowed adequate and safe decompression of lumbar stenosis, resulted in a highly significant reduction of symptoms and disability, and improved health-related quality of life. Outcome after unilateral laminotomy was comparable with that after laminectomy. In most outcome parameters, bilateral laminotomy was associated with a significant benefit and thus constitutes a promising treatment alternative.

Prospective outcomes evaluation after decompression with or without instrumented fusion for lumbar stenosis and degenerative Grade I spondylolisthesis

OBJECT

There is considerable debate among spine surgeons regarding whether fusion should be used to augment decompressive surgery in patients with symptomatic lumbar spinal stenosis involving Grade I degenerative spondylolisthesis. The authors prospectively evaluated the outcomes of patients treated between 2000 and 2002 at two institutions to determine whether fusion improves functional outcome 1 year after surgery.

METHODS

Patients ranged in age from 50 to 81 years. They presented with degenerative Grade I (3- to 14-mm) spondylolisthesis and lumbar stenosis without gross instability (< 3 mm of motion at the level of subluxation). Those in whom previous surgery had been performed at the level of subluxation were excluded. Each patient completed Oswestry Disability Index (ODI) and Short Form-36 (SF-36) questionnaires preoperatively and at 6 to 12 months postoperatively. Some patients underwent decompression alone (20 cases), whereas others underwent decompression and posterolateral instrumentation-assisted fusion (14 cases), at the treating surgeon's discretion. Baseline demographic data, radiographic features, and ODI and SF-36 scores were similar in both groups. The 1-year fusion rate was 93%. Both forms of surgery independently improved outcome compared with baseline status, based on ODI and SF-36 physical component summary (PCS) results (p < 0.001). Decompression combined with fusion led to an improvement in ODI scores of 27.5 points, whereas decompression alone was associated with a 13.6-point increase (p = 0.02). Analysis of the SF-36 PCS data also demonstrated a significant intergroup difference (p = 0.003).

CONCLUSIONS

Surgery substantially improved 1-year outcomes based on established outcomes instruments in patients with Grade I spondylolisthesis and stenosis. Fusion was associated with greater functional improvement.