Clinical Results of Intrapedicular Partial Pediculectomy for Lumbar Foraminal Stenosis

Risk Factors of Restenosis After Full Endoscopic Foraminotomy for Lumbar Foraminal Stenosis: Case-Control Study

OBJECTIVE

To investigate risk factors associated with postoperative restenosis after full endoscopic lumbar foraminotomy (FELF) in patients with lumbar foraminal stenosis (LFS).

METHODS

A single-center, retrospective case-control study was conducted on patients diagnosed with foraminal stenosis who underwent FELF between August 2019 and April 2022. The study included 56 patients, comprising 18 cases and 38 controls. Clinical data, radiologic assessments, and surgical types were compared between the groups. The cutoff values of radiologic parameters that differentiate the 2 groups were investigated.

RESULTS

No significant difference in age, sex distribution, or presence of adjacent segment disease or grade I spondylolisthesis was observed between the groups. Cases had a higher degree of disc wedging angle (DWA) (3.0° ± 1.1° vs. 0.5° ± 1.4°, p < 0.001), larger coronal Cobb angle (CCA) (8.8° ± 5.1° vs. 4.7° ± 2.5°, p = 0.004), and smaller segmental lumbar lordosis (SLL) than controls (11.0 ± 7.4 vs. 18.0 ± 5.4, p = 0.001). Optimal cutoff values for DWA, CCA, and SLL were estimated as 1.8°, 7.9°, and 17.1°, respectively. A significant difference in surgical types was observed between cases and controls (p = 0.004), with the case group having a higher distribution of patients undergoing discectomy in addition to TELF.

CONCLUSION

The study identified potential risk factors for restenosis after FELF in patients with LFS, including higher DWA, larger CCA, smaller SLL angle. We believe that discectomy should be perform with caution during FELF, as it can lead to subsequent restenosis.

Microendoscopic decompression for lumbar spinal stenosis caused by facet-joint cysts: a novel technique with a cyst-dyeing protocol and cohort comparison study

OBJECTIVE

Facet cysts may represent a sign of intrinsic facet disease and instability, increasing the importance of less-invasive approaches that limit tissue dissection and improve visualization. The authors developed an intraoperative cyst-dyeing technique, involving the injection of indigo carmine from the facet joint into the cyst, as an adjunct during decompression. This study aimed to evaluate the clinical outcomes and perioperative complication rates of microendoscopic spinal decompression for lumbar spinal stenosis (LSS) and lumbar foraminal stenosis (LFS), caused by facet cysts and to elucidate the efficacy of the cyst-dyeing method in microendoscopic surgery for facet cysts.

METHODS

Forty-eight consecutive patients who underwent surgical treatment with microendoscopic decompression for symptomatic LSS or LFS caused by facet cysts from 2011 to 2018 were reviewed. These patients were divided into two groups: a group that did not receive dye (N), with the patients undergoing surgery from April 2011 to May 2015; and a group that received dye (D), with patients undergoing surgery from June 2015 to March 2018. The authors evaluated the operative time, blood loss, perioperative complications, visual analog scale scores for low-back and leg pain, and Japanese Orthopaedic Association scores. Surgical outcome was evaluated 2 years postoperatively and was compared between groups D and N.

RESULTS

The clinical outcomes were generally excellent or good. Group N consisted of 36 patients and group D of 12 patients. Comparing the clinical results, it was found that the cyst-dyeing method reduced the perioperative complication rate, including reduction in dural tears to 0%, and shortened the average operative time by approximately 40 minutes.

CONCLUSIONS

In this study, the authors demonstrated that the clinical outcomes of microendoscopic spinal decompression in patients with LSS or LFS caused by facet-joint cysts are generally favorable. Additionally, the adjunctive cyst-dyeing method effectively delineated the cystic and dural boundaries, facilitating safer and more effective cyst separation and neural decompression. Microendoscopic surgery combined with this novel facet cyst-dyeing method is a safe and effective minimally invasive technique for facet-joint cysts.

Microendoscopic decompression for lumbosacral foraminal stenosis: a novel surgical strategy based on anatomical considerations using 3D image fusion with MRI/CT

OBJECTIVE

Persistent lumbar foraminal stenosis (LFS) is one of the most common reasons for poor postoperative outcomes and is a major contributor to "failed back surgery syndrome." The authors describe a new surgical strategy for LFS based on anatomical considerations using 3D image fusion with MRI/CT analysis.

METHODS

A retrospective review was conducted on 78 consecutive patients surgically treated for LFS at the lumbosacral junction (2013-2017). The location and extent of stenosis, including the narrowest site and associated pathology (bone or soft tissue), were measured using 3D image fusion with MRI/CT. Stenosis was defined as medial intervertebral foraminal (MF; inner edge to pedicle center), lateral intervertebral foraminal (LF; pedicle center to outer edge), or extraforaminal (EF; outside the pedicle). Lumbar (low-back pain, leg pain) and patient satisfaction visual analog scale (VAS) scores and Japanese Orthopaedic Association (JOA) scores were evaluated. Surgical outcome was evaluated 2 years postoperatively.

RESULTS

Most instances of stenosis existed outside the pedicle's center (94%), including LF (58%), EF (36%), and MF (6%). In all MF cases, stenosis resulted from soft-tissue structures. The narrowest stenosis sites were localized around the pedicle's outer border. The areas for sufficient nerve decompression were extended in MF+LF (10%), MF+LF+EF (14%), LF+EF (39%), LF (11%), and EF (26%). No iatrogenic pars interarticularis damage occurred. The JOA score was 14.9 ± 2.6 points preoperatively and 22.4 ± 3.5 points at 2 years postoperatively. The JOA recovery rate was 56.0% ± 18.6%. The VAS score (low-back and leg pain) was significantly improved 2 years postoperatively (p < 0.01). According to patients' self-assessment of the minimally invasive surgery, 62 (79.5%) chose "surgery met my expectations" at follow-up. Nine patients (11.5%) selected "I did not improve as much as I had hoped but I would undergo the same surgery for the same outcome."

CONCLUSIONS

Most LFS existed outside the pedicle's center and was rarely noted in the pars region. The main regions of stenosis were localized to the pedicle's outer edge. Considering this anatomical distribution of LFS, the authors recommend that lateral fenestration should be the first priority for foraminal decompression. Other surgical options including foraminotomy, total facetectomy, and hemilaminectomy likely require more bone resections than LFS treatment. The microendoscopic surgery results were very good, indicating that this minimally invasive surgery was suitable for treating this disease.

Percutaneous Stenoscopic Lumbar Decompression with Paramedian Approach for Foraminal/Extraforaminal Lesions

The lumbar foramen is affected by different degenerative diseases, including extraforaminal disc herniation, foraminal stenosis (FS), and degenerative or spondylolytic spondylolisthesis. The purpose of this study was to describe percutaneous stenoscopic lumbar decompression with a paramedian approach (para-PSLD) for foraminal/extraforaminal lesions. All operative procedures were performed using a complete uniportal endoscopic instrument system. The para-PSLD can be easily applied to patients with FS and narrow disc space or facet joint hypertrophy. The anatomical view of a para-PSLD is similar to that of a conventional open surgery and allows for good visualization of the foraminal/extraforaminal areas. We suggest that para-PSLD is an alternative and minimally invasive procedure to treat degenerative lumbar foraminal/extraforaminal stenoses.

Predictors of Clinical Outcome After Endoscopic Partial Facetectomy for Degenerative Lumbar Foraminal Stenosis

OBJECTIVE

Endoscopic partial facetectomy (EPF) is an effective option for decompressing the lumbar exiting root without causing spinal instabilities in the treatment of patients with degenerative lumbar foraminal stenosis. The aim of the present study was to identify the preoperative risk factors of poor clinical outcomes after EPF in patients with degenerative lumbar foraminal stenosis.

METHODS

A total of 51 consecutive patients who had undergone EPF from 2012 to 2015 were included in the present study. The clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry disability index (ODI), and Short-Form 36-item (SF-36) outcome questionnaires. The preoperative radiological risk factors were measured using the lumbar Cobb's angle, disc wedging angle, lumbar lordosis (LL), segmental lordosis, disc height index, presence of spondylolisthesis, and morphological changes (no change, horizontal collapse, vertical collapse) of the exiting root within the most stenotic level on preoperative magnetic resonance imaging.

RESULTS

The VAS, ODI, and SF-36 scores had significantly improved at the 1-month follow-up visit compared with the baseline mean values and were maintained within the 2-year follow-up period. A correlation analysis revealed significant relationships between various preoperative factors and clinical outcomes. On multiple regression analysis, the morphological change of vertical collapse significantly predicted the VAS, ODI, and SF-36 scores, and LL significantly predicted the ODI and SF-36 scores.

CONCLUSIONS

A morphological change in vertical collapse found on preoperative magnetic resonance imaging and decreased LL were significant predictors of poor clinical outcomes after EPF in the treatment of lumbar foraminal stenosis.

Biportal Endoscopic Spinal Surgery for Bilateral Lumbar Foraminal Decompression by Switching Surgeon's Position and Primary 2 Portals: A Report of 2 Cases With Technical Note

Total facetectomy with/without fusion and facet-preserving microforaminotomy have been performed as conventional surgical treatments for lumbar foraminal stenosis (LFS). Recently, endoscopic spinal surgery has been introduced as a minimally invasive therapeutic modality of LFS by several authors. We report two cases of bilateral LFS at lumbosacral junction level successfully treated with a novel biportal endoscopic spine surgery (BES) technique using primary 2 portals. Two patients presented with chronic onset of back pain and neurogenic claudication symptom. They were diagnosed with bilateral LFS at L5-S1 level from magnetic resonance imaging and computed tomography preoperatively. BES for bilateral foraminal decompression was performed via contralateral approach bilaterally without additional skin incision or surgical trajectory by switching surgeon's position and primary 2 portals. After the surgery, preoperative patients' back and leg pain resolved and unilateral leg weakness of the 2 patients gradually improved in a few months. Postoperative radiologic images revealed significantly enlarged bilateral foramens at L5-S1 level.

Outcome of Decompression Alone for Foraminal/Extraforaminal Entrapment of L5 Nerve Root Through Wiltse Paraspinal Approach

STUDY DESIGN

Retrospective analysis.

OBJECTIVE OF THE STUDY

The objective of the study was to present the surgical outcome and analyze the prognostic factors for postoperative leg pain after posterior decompression alone for foraminal/extraforaminal L5 entrapment at L5-S1 segment (LSS).

SUMMARY OF BACKGROUND DATA

Disk extrusion, hypertrophy of facet joint, osteophyte of vertebral body, thickened lumbosacral ligament, and collapsed disk lead to form the lumbosacral tunnel which compresses the L5 exiting nerve root. There are few reports discussing the outcome and prognostic factors of posterior decompression alone.

MATERIALS AND METHODS

One hundred two consecutive patients underwent posterior decompressive surgery through Wiltse approach for foraminal/extraforaminal entrapment at LSS, performed by 2 surgeons. Demography and preoperative radiograph were analyzed for 6 parameters: age, pathology, disk height, relative disk height ratio, depth of L5 vertebrae within the pelvis, and coronal wedging angle of the segment. Clinical outcomes were assessed by the Visual Analog Scale score for back and leg pain, Oswestry Disability Index, and modified Macnab criteria. The incidence of medications of anticonvulsants, opioids, epidural nerve root block and revisional surgery at index level were also examined.

RESULTS

This study included 93 patients. The mean follow-up period was 40.6±19.7 months. Thirty-six patients had disk herniation and 57 had stenosis. Preoperative Visual Analog Scale score and Oswestry Disability Index significantly improved at the final follow-up. On the basis of the modified Macnab criteria, 83% of the patients had good outcomes at follow-up. The mean duration of the medications of anticonvulsants or opioids is 27.2±37.4 days (0-210 d). 5 patients (5.4%) were reoperated. Relative disk height ratio <0.8 was associated with worsening of postoperative leg pain (P<0.01).

CONCLUSIONS

Decompression as the only method for foraminal/extraforminal lesion of LSS through Wiltse paraspinal approach provided good clinical results. A large difference of disk height between standing and supine positions is associated with poor clinical outcomes.

Assessment of Clinical Symptoms in Lumbar Foraminal Stenosis Using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire

Objective

It is important to develop an easy means of diagnosing lumbar foraminal stenosis (LFS) in a general practice setting. We investigated the use of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) to diagnose LFS in symptomatic patients.

Methods

Subjects included 13 cases (mean age, 72 years) with LFS, and 30 cases (mean age, 73 years) with lumbar spinal canal stenosis (LSCS) involving one intervertebral disc. The visual analogue scale score for low back pain and leg pain, the JOABPEQ were evaluated.

Results

Those with LFS had a significantly lower JOA score (p<0.001), while JOABPEQ scores (p<0.05) for lumbar dysfunction and social functioning impairment (p<0.01) were both significantly lower than the scores in LSCS. The following JOABPEQ questionnaire items (LFS vs. LSCS, p-value) for difficulties in: sleeping (53.8% vs. 16.6%, p<0.05), getting up from a chair (53.8% vs. 6.6%, p<0.001), turning over (76.9% vs. 40%, p<0.05), and putting on socks (76.9% vs. 26.6%, p<0.01) such as pain during rest, and signs of intermittent claudication more than 15 minutes (61.5% vs. 26.6%, p<0.05) were all significantly more common with LFS than LSCS.

Conclusion

Results suggest that of the items in the JOABPEQ, if pain during rest or intermittent claudication is noted, LFS should be kept in mind as a cause during subsequent diagnosis and treatment. LFS may be easily diagnosed from LSCS using this established patient-based assessment method.

Microsurgical Foraminotomy via Wiltse Paraspinal Approach for Foraminal or Extraforaminal Stenosis at L5-S1 Level : Risk Factor Analysis for Poor Outcome

Objective

The purpose of this study was to present the outcome of the microsurgical foraminotomy via Wiltse paraspinal approach for foraminal or extraforaminal (FEF) stenosis at L5–S1 level. We investigated risk factors associated with poor outcome of microsurgical foraminotomy at L5–S1 level.

Methods

We analyzed 21 patients who underwent the microsurgical foraminotomy for FEF stenosis at L5–S1 level. To investigate risk factors associated with poor outcome, patients were classified into two groups (success and failure in foraminotomy). Clinical outcomes were assessed by the visual analogue scale (VAS) scores of back and leg pain and Oswestry disability index (ODI). Radiographic parameters including existence of spondylolisthesis, existence and degree of coronal wedging, disc height, foramen height, segmental lordotic angle (SLA) on neutral and dynamic view, segmental range of motion, and global lumbar lordotic angle were investigated.

Results

Postoperative VAS score and ODI improved after foraminotomy. However, there were 7 patients (33%) who had persistent or recurrent leg pain. SLA on neutral and extension radiographic films were significantly associated with the failure in foraminotomy (p<0.05). Receiver-operating characteristics curve analysis revealed the optimal cut-off values of SLA on neutral and extension radiographic films for predicting failure in foraminotomy were 17.3° and 24°s, respectively.

Conclusion

Microsurgical foraminotomy for FEF stenosis at L5–S1 level can provide good clinical outcomes in selected patients. Poor outcomes were associated with large SLA on preoperative neutral (>17.3°) and extension radiographic films (>24°).

Discrimination between Lumbar Intraspinal Stenosis and Foraminal Stenosis using Diffusion Tensor Imaging Parameters: Preliminary Results

Study Design

Retrospective observational study.

Purpose

To examine fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values of damaged nerves to discriminate between lumbar intraspinal stenosis (IS) and foraminal stenosis (FS) using diffusion tensor imaging (DTI)

Overview of Literature

It is important in the selection of surgical procedure to discriminate between lumbar IS and FS, but such discrimination is difficult.

Methods

There were 9 cases of IS, 7 cases of FS, and 5 healthy controls. The regions of interest were established in the lumbar intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez). The FA and ADC values were measured on the affected and unaffected sides of the nerves. The FA ratio and the ADC ratio were calculated as the affected side/unaffected side ×100 (%).

Results

In the Ez, the FA value was significantly lower in FS than in IS (p<0.01). FA ratio was significantly lower in FS than in IS for the Ez (p<0.01). In the Iz, the ADC value was significantly higher in IS than FS (p<0.01). ADC ratio was significantly higher in FS than in IS for the N and Ez (p<0.05). For the Ez, receiver operating characteristic analysis of parameters revealed that the FA values showed a higher accuracy for the diagnosis of FS than the ADC values, and the FA value cut-off value was 0.42 (sensitivity: 85.7%, false positive: 11.1%) and the FA ratio cut-off value was 83.9% (sensitivity: 85.7%, false positive: 22.2%).

Conclusions

The low FA value in the extraforaminal zone suggests the presence of foraminal stenosis. When the FA value and FA ratio cut-off value were established as 0.42 and 83.9%, respectively, the accuracy was high for the diagnosis of foraminal stenosis. It may be possible to use DTI parameters to help in the discrimination between IS and FS.

The diagnosis of double-crush lesion in the L5 lumbar nerve using diffusion tensor imaging

BACKGROUND CONTEXT

A double-crush lesion is a condition in which the lumbar nerve is compressed both medially and laterally in the spinal canal, where diagnosis can be very difficult, and is a factor leading to poor surgical success rates.

PURPOSE

Diffusion tensor imaging (DTI) was used to determine DTI parameter fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) in both intraspinal column lesions alone and in double-crush lesions.

STUDY DESIGN

This study used a prospective study.

PATIENT SAMPLE

Of the 56 cases (mean age: 72.2 years) that underwent laminectomy for lumbar spinal stenosis at our clinic between April 2013 to March, 2015, 10 cases with L5 radiculopathy caused by L4-L5 stenosis (Intraspinal stenosis group (Group I); mean age: 74.7 years), and 5 cases with persistent symptoms caused by L5 foraminal stenosis despite L4-L5 decompression surgery (Double-crush group (Group D); mean age: 77.6 years) were targeted. One patient in Group D was diagnosed through microendoscopic intrapedicular partial pediculotomy and the remaining four cases by nerve root infiltration. Five healthy cases (mean age: 54 years) were studied as controls.

OUTCOME MEASURES

Intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez) were established as the regions of interest, and the L5 nerve FA and ADC values were determined on the affected side.

METHODS

Diffusion tensor imaging was performed prospectively by 1.5T magnetic resonance imaging before surgery, and DTI parameters of L5 nerve were evaluated in all patients and healthy volunteers. Student t test was used for group comparisons, and a p<.05 was considered statistically significant.

RESULTS

Fractional anisotropy values (Iz, N, Ez) were 0.415, 0.448, and 0.517, respectively, increasing as sites became more distal. Group I values were 0.335, 0.393, and 0.484, and Group D values were 0.296, 0.367, and 0.360. Compared with the healthy volunteers, Group D had significantly lower Iz (p<.05) and Ez (p<.001) values, while Group I had significantly lower Iz (p<.05) values. In Group D, Ez FA values were significantly lower (p<.001) than in Group I. Apparent diffusion coefficient values (Iz, N, Ez) in the healthy control group were 1.270 mm2/s, 1.151 mm2/s, and 0.937 mm2/s with values decreasing as sites grew distal. In Group I, the ADC values were 1.406 mm2/s, 1.184 mm2/s, and 1.001 mm2/s, while in Group D they were 1.551 mm2/s, 1.412 mm2/s, and 1.329 mm2/s. Compared with the healthy volunteers, Iz (p<.05) and Ez (p<.05) values were significantly higher in Group D. The N (p<.01) and Ez (p<.001) ADC values were significantly higher in Group D than in Group I.

CONCLUSIONS

Depending on where the nerve was compressed, changes in DTI parameters revealed nerve damage (low FA values and increased ADC) in the intraspinal canal in the Intraspinal Group, and over a widespread area in the Double-crush Group spanning the medial to lateral spinal canal. Our research suggests that in cases where double crush is suspected before surgery, failed back surgery syndrome may be prevented by evaluating DTI images.

Extreme lateral interbody fusion for unilateral symptomatic vertical foraminal stenosis

PURPOSE

Asymmetric loss of disc height in adult deformity patients may lead to unilateral vertical foraminal stenosis and radiculopathy. The current study aimed to investigate whether restoration of foraminal height on the symptomatic side using extreme lateral interbody fusion (XLIF) would alleviate unilateral radiculopathy.

METHODS

In a retrospective study, patients with single-level unilateral vertical foraminal stenosis and corresponding radicular pain undergoing XLIF were included. Functional data (visual analog scale (VAS) for buttock, leg and back, as well as Oswestry Disability Index (ODI)) and radiographic measurements (bilateral foraminal height, disc height, segmental coronal Cobb angle and regional lumbar lordosis) were collected preoperatively, postoperatively and at the last follow-up.

RESULTS

Twenty-three patients were included, among whom 61 % had degenerative scoliosis. History of previous surgery at the level of index was present in 43 % of patients. Additional instrumentation was performed in 91 %. The foraminal height on the stenotic side was significantly increased postoperatively (p < 0.001), and remained significantly increased at the last follow-up of 11 ± 3.7 months (p < 0.001). Additionally, VAS buttock and leg on the stenotic side, VAS back and ODI were significantly improved postoperatively and at the last follow-up (p ≤ 0.001 for all parameters). The foraminal height on the stenotic side showed correlation with the VAS leg on the stenotic side, both postoperatively and the last follow-up (r = -0.590; p = 0.013, and r = -0.537; p = 0.022, respectively).

CONCLUSIONS

Single-level XLIF is an effective procedure for treatment of symptomatic unilateral foraminal stenosis leading to radiculopathy. In deformity patients with radicular pain caused by nerve compression at a single level, when not associated with other symptoms attributable to general scoliosis, treatment with single-level XLIF can result in short- and mid-term satisfactory outcome.

Microsurgical extraforaminal decompression of lumbar root canal stenosis

OBJECTIVE

To decompress the lumbar spinal nerve impinged peripherally to the lateral recess. To avoid in selected cases the pedicle screw fixation and fusion of the segment.

INDICATION

Single level radiculopathy in degenerative scoliosis or in degenerative disc disease without segmental instability.

CONTRAINDICATIONS

Scoliosis > 30° at the index level, lateral listhesis > 6 mm, mobile vertebral slip.

SURGICAL TECHNIQUE

Microscope from skin to skin. A 35-mm skin incision about 40 mm off the midline. Transmuscular access by blunt splitting of the paravertebral muscles pointing about 40° towards the midline. Insertion of an expandable tubular retractor or of a speculum counter retractor system. Dissection of the target lumbar nerve in the midst of the extraforaminal fat tissue. Enlargment of the root canal mostly by drilling and using thin foot plate punches. The nerve is decompressed from peripherally to the lateral rim of the yellow ligament. Closure by layers. Drainage is usually not required.

POSTOPERATIVE MANAGEMENT

Same day mobilization.

RESULTS

The clinical results in 22 cases (15 men) of extraforaminal nerve root involvement were studied. Because of the very selective indication the patients were recruited over a 3-year time-span. The mean age was 64 years (range 50-82 years). An independent follow-up examination was performed 3 months and 1 year following surgery. The mean FU was 27 months (range 41-22 months). According to the modified MacNab criteria, the results were excellent (45%), good (23%), fair (14%), and poor (18%). Four patients underwent second surgery for pedicle screw fixation and fusion. Persistent low back pain was the most common cause of an unsatisfactory postoperative course.

Clinical and radiological outcomes of microscopic partial pediculectomy for degenerative lumbar foraminal stenosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the clinical outcomes of microscopic partial pediculectomy for degenerative lumbar craniocaudal foraminal stenosis, risk factors for postsurgical scoliosis progression, and feasibility of postsurgical pedicle screw insertion.

SUMMARY OF BACKGROUND DATA

Previous studies have evaluated surgical strategies for degenerative lumbar foraminal stenosis. Although less invasive decompression surgery is an option for surgical treatment, postsurgical instability and salvaging fusion surgery remain as problems. No analysis has focused on the radiological progression and feasibility of pedicle screw setting after pediculectomy.

METHODS

Microscopic partial pediculectomy by our original method was performed as a first-choice surgical treatment for lumbar radiculopathy due to degenerative craniocaudal foraminal stenosis. This study included 50 consecutive patients followed up for a minimum of 2 years. Clinical outcomes were evaluated with Japanese Orthopaedic Association (JOA) scores and a numerical rating scale. Radiological changes were obtained from standing radiographs. Foraminal height and the minimum pedicle diameter were measured by reconstructed images on multidetector row computed tomography.

RESULTS

The preoperative Japanese Orthopaedic Association score of 14.2 ± 4.2 significantly improved to 21.5 ± 6.2, and 60% of patients were satisfied. The numerical rating scale for lumbar back pain, leg pain, and leg numbness significantly improved. Nine patients (18%) showed lumbar Cobb angle progression of 5° or more within 2 years, and the risk factor for scoliosis progression was surgery at L3-L4 or L4-L5 by multivariate logistic regression analysis. Foraminal height was enlarged from 5.4 mm preoperatively to 8.9 mm postoperatively. The postoperative minimum pedicle diameter was 8.7 ± 1.6 (5.9-11.7) mm.

CONCLUSION

Microscopic lumbar partial pediculectomy provided satisfactory clinical outcomes, but early postsurgical scoliosis progression was likely to occur in patients who underwent the surgery at L3-L4 or L4-L5. Even if a second surgical procedure is needed, pedicle screws can be set on the resected pedicle.

LEVEL OF EVIDENCE

4.

[Lumbar spinal nerve roots imaging using balanced sequence with inversion recovery (IR) pulse]

We devised a method for visualizing the distal portion of lumbar spinal nerve roots in the direction of the long axis using a three-dimensional balanced sequence with inversion recovery pulse, and we established the imaging parameters. This pulse sequence was used with the following parameters: 260 mm field of view, 4.8 ms repetition time, 2.4 ms echo time, 90 degree flip angle, 1.5 mm slice thickness (0.75 mm overlap), and low-high radial k-space profile order. We assessed the signal intensity and contrast for the phantom and healthy volunteer images with different inversion times (TI). Moreover, we evaluated this method by using the optimal TI in clinical cases. The optimal TI obtained from the phantom and human studies was 600 ms. In clinical cases, this method with 600 ms of TI provided the best definition in images of abnormal pathway and compression of the lumbar spinal nerve roots. Our imaging method makes it possible to clearly and noninvasively visualize the lumbar spinal nerve roots.

Clinical outcomes of microscopic decompression for degenerative lumbar foraminal stenosis: a comparison between patients with and without degenerative lumbar scoliosis

We performed microscopic lumbar foraminotomy in all the patients diagnosed with degenerative lumbar foraminal stenosis (DLFS) and retrospectively reviewed the clinical outcomes and the factors influencing them. The preoperative Japanese Orthopaedic Association (JOA) score of 13.8 significantly improved to 21.9 postoperatively. Although leg pain reduced in 44 patients (95.7%) immediately after surgery, it recurred in 9 patients (19.6%). The recurrence frequency was significantly higher and the JOA score improvement ratios significantly lower in patients with degenerative lumbar scoliosis (DLS) than in those without DLS. Even among patients with DLS, those with <3° Cobb angle difference between the supine and standing positions showed satisfactory results, with no recurrence. In conclusion, microscopic lumbar foraminotomy for DLFS produced satisfactory clinical outcomes even in patients with DLS. However, the outcomes were poor in patients with unstable DLS.

Unilateral augmented pedicle screw fixation for foraminal stenosis

OBJECTIVE

The purpose of this study is to evaluate the effectiveness of unilateral decompression and pedicle screw fixation for the unilateral symptomatic foraminal stenosis.

METHODS

The study group comprises consecutive 16 patients who underwent unilateral decompression and bone cement augmented pedicle screw fixation from May 2003 to January 2006. The patients were evaluated by visual analog scale (VAS) for pain and the scoring system of the Japanese Orthopedic Association (JOA) for low back pain. The result of surgery was also evaluated with McNab's classification. Excellent or good outcome was considered as successful. The patients were followed at postoperative 1 month, 3 month, 6 month, and 1 year with standing AP and lateral films.

RESULTS

The average VAS and JOA score of the 16 patients were 7.8 (range, 6-9) and 5.8 (range, 3 - 10) before surgery and 2.2 (range, 0 - 5) and 12.3 (range, 9 - 15) at the time of last follow up. Both VAS and JOA score improved significantly after the surgery (p < 0.05, t-test). All patients improved after the operation and no revision surgery was required. No metal failure or pseudoarthrosis was observed during the follow-up. The success rate was 87.5%.

CONCLUSION

Our data suggest that unilateral decompression and pedicle screw fixation for the unilateral symptomatic foraminal stenosis is an effect method for obtaining satisfactory clinical outcome. Its possible advantage is shorter operation time and reduced surgical extent. We believe that the reduced stiffness of unilateral fixation was compensated by pedicle screw augmentation and interbody fusion.