Change of Lumbar Ligamentum Flavum after Indirect Decompression Using Anterior Lumbar Interbody Fusion

Short-Term Clinical and Radiographic Evaluation of Patients Treated With Expandable and Static Interbody Spacers Following Lumbar Lateral Interbody Fusion

OBJECTIVE

The goal of this study was to evaluate, using computed tomography (CT) and magnetic resonance imaging (MRI), patients who underwent oblique lateral interbody fusion (OLIF) using either expandable or static interbody spacers.

METHODS

Thirty-five patients with degenerative disc disease were surgically treated with one-level OLIF and were followed up for more than 6 months. The Static group consisted of 22 patients, and 13 patients were in the Expandable group. Intraoperative findings included operative time (min), blood loss (ml), and cage size. Low back pain, leg pain, and leg numbness were measured using the Japanese Orthopedic Association score, visual analogue score, and the Roland-Morris Disability Questionnaire. Radiologic evaluation using computed tomography (CT) and magnetic resonance imaging (MRI) allowed measurement of cage subsidence, cross-sectional area (CSA) of the dural sac, disc height, segmental lordosis, foraminal height, and foraminal CSA preoperatively and 6 months postoperatively.

RESULTS

The Expandable group had significantly larger cage height and lordosis than the Static group (P < 0.05). The Expandable group also had greater dural sac area expansion and enlargement of the intervertebral foramen, as well as better correction of vertebral body slip (P < 0.05). Cage subsidence was significantly lower in the Expandable group (P < 0.05). JOA and VAS scores for leg numbness were significantly better in the Expandable group (P < 0.05).

CONCLUSIONS

Compared with static spacers, expandable spacers significantly enlarged the dural sac area, corrected vertebral body slippage, expanded the intervertebral foramen, and achieved good indirect decompression while reducing cage subsidence, resulting in improvement in clinical symptoms.

Factors affecting successful immediate indirect decompression in oblique lateral interbody fusion in lumbar spinal stenosis patients

Background

Oblique lumbar interbody fusion (OLIF) offers indirect decompression of stenotic lesions of the spinal canal and foramen through immediate disc height restoration. Only a few studies have reported the effect of cage position and associated intraoperatively modifiable factors for successful immediate indirect decompression following OLIF surgery. This study aimed to investigate the intraoperatively modifiable factors for successful radiological outcomes of OLIF.

Methods

This study included 46 patients with 80 surgical levels who underwent OLIF without direct posterior decompression. Preoperative and postoperative radiological parameters were evaluated and intraoperatively modifiable radiologic parameters for successful immediate radiologic decompression on magnetic resonance image (MRI) were determined. Radiologic parameters were preoperative and postoperative radiological parameters including anterior disc height (ADH), posterior disc height (PDH) lumbar lordotic angle (LLA), segmental lordotic angle (SLA), foraminal height (FH), cage position, cross-sectional area (CSA) of the thecal sac, cross-sectional foraminal area (CSF), facet distance (FD).

Results

All radiologic outcomes significantly improved. Comparing preoperative and postoperative values, mean CSA increased from 99.63±40.21 mm2 to 125.02±45.90 mm2 (p<.0001), and mean left CSF increased from 44.54±12.90 mm2 to 69.91±10.80 mm2 (p<.0001). FD also increased from 1.40±0.44 to 1.92±0.71 mm (p<.0001). FH increased from 16.31±3.3 to 18.84±3.47 mm (p<.0001). ADH and PDH also significantly increased (p<.0001). Immediate postoperative CSF and FH improvement rate (%) were significantly correlated with posterior disc height restoration rate (%) (p=.0443, and p=.0234, respectively). In addition, the patients with a cage positioned in the middle of the vertebral body experienced a greater FH improvement rate (%) compared to the patients with a cage positioned anteriorly. Finally, Visual analogue scale (VAS) for leg pain was improved immediately.

Conclusions

OLIF provided satisfactory immediate indirect decompression in central and foraminal spinal stenosis. Moreover, intraoperative surgical technique for successful radiologic CSF and FH improvement included restoration of the PDH and placement of the cage in the middle.

Oblique lateral interbody fusion (OLIF) compared with unilateral biportal endoscopic lumbar interbody fusion (ULIF) for degenerative lumbar spondylolisthesis: a 2-year follow-up study

BACKGROUND

Oblique lumbar interbody fusion (OLIF) has been proven to be an effective method of indirect decompression for the treatment of Degenerative Lumbar Spondylolisthesis (DLS). However, its superiority over Unilateral biportal endoscopic Lumbar Interbody Fusion (ULIF) has not been reported yet. The current study aimed to compare the clinical and radiological outcomes of OLIF and ULIF in patients with DLS.

METHODS

A total of 107 patients were included in this study, divided into two groups according to the surgical methods with 45 patients treated by OLIF combined with anterolateral single screwrod fixation, and 62 patients treated by ULIF. To compare the perioperative parameters (blood loss, operation time, and postop hospitalization) and clinical (the Visual Analog Scale (VAS) scores of the low back pain and leg pain and the Oswestry Disability Index (ODI)) and radiological (disk height (DH), lumbar lordosis (LL), segmental lordosis (SL), the cross-sectional area (CSA) of the spinal canal) results of the two surgical approaches to evaluate their efficacy.

RESULTS

Compared with the ULIF group, the blood loss and operation time in the OLIF-AF group were significantly reduced, and the Postop hospitalization was comparable. The VAS scores in both groups were significantly improved compared to preop; however, the VAS score of low back pain in the OLIF-AF group was superior to that in ULIF group throughout the follow-up period (P < 0.05). The improvements in DH, LL, and Segmental angle were significantly lower in the ULIF group, and the expansion rate of CSA in the OLIF-AF group was superior to that in the ULIF group, but the difference was not statistically significant. The fusion rate in OLIF-AF group was significantly higher than that in ULIF group within 6 mo postop, and there was no significant difference at the last follow-up. The incidence of complications was comparable between the two groups, and there was no statistical difference.

CONCLUSIONS

Both OLIF-AF and ULIF achieved good short-term results in the treatment of DLS, and both surgical approaches are desirable. However, OLIF-AF has advantages over ULIF in terms of postoperative restoration of lumbar sagittal parameters and earlier intervertebral fusion. Long-term follow-up and larger clinical studies are needed to confirm this result.

Comparison of ligamentum flavum thickness between central and lateral lesions in a patient with central lumbar spinal canal stenosis

Thickened ligamentum flavum has been considered as a major cause of central lumbar spinal canal stenosis (CLSCS). Previous studies have demonstrated that ligamentum flavum thickness (LFT) is correlated with aging, degenerative spinal stenosis, and disc degeneration. Thus, hypertrophy of the ligamentum flavum is a major cause of CLSCS, and measurement of LFT has been considered a morphologic parameter in the diagnosis of CLSCS. To our knowledge, comparison of LFT between central and lateral lesions has not been reported. In addition, no research has analyzed best clinical cutoff values of central ligament flavum thickness (CLFT) and lateral ligament flavum thickness (LLFT). This study aimed to compare CLFT with LLFT in patients with CLSCS and further compare the CLFT and LLFT findings between the 2 groups to analyze LFT variation. Both CLFT and LLFT samples were collected from 101 participants with CLSCS and from 103 participants in the control group who underwent lumbar magnetic resonance imaging without evidence of CLSCS. Axial T2-weighted lumbar magnetic resonance scans were acquired at the L4 to 5 facet joint level from each participant. Average CLFT value was 2.25 ± 0.51 mm in the control group and 4.02 ± 0.74 mm in the CLSCS group. Average LLFT value was 2.50 ± 0.51 mm in the control group and 3.38 ± 0.66 mm in the CLSCS group. CLSCS patients had significantly higher CLFT and LLFT (both P < .001). Regarding the validity of both CLFT and LLFT as predictors of CLSCS, a receiver operating characteristic estimation revealed that the most suitable cutoff value for CLFT was 3.10 mm, with sensitivity of 95.0%, specificity of 94.2%, and an area under the curve of 0.97. The best cut-off value of LLFT was 2.92 mm, with sensitivity of 78.2%, specificity of 77.7%, and area under the curve of 0.87. We have 4 important new findings: The mean CLFT is significantly lower than that of the mean LLFT in the normal control group; CLFT and LLFT are both significantly associated with CLSCS; Increase rate of CLFT is faster than that of LLFT in the CLSCS group; and CLFT is a more sensitive measurement parameter to predict CLSCS than LLFT.

Comparison between OLIF and MISTLIF in degenerative lumbar stenosis: an age-, sex-, and segment-matched cohort study

To compare outcomes after oblique lateral interbody fusion (OLIF) versus minimally invasive transforaminal lumbar interbody fusion (MISTLIF) with bilateral decompression via unilateral approach for treating mild to moderate symptomatic degenerative lumbar spinal stenosis (DLSS). We retrospectively compared patients who underwent single-level (L4/5) OLIF with an age-, sex-, and segment-matched MISTLIF with bilateral decompression via unilateral approach cohort. Perioperative data were collected for the operative time, intraoperative blood loss, drainage in the first postoperative day, postoperative hospital stay, cost, intraoperative fluoroscopy, and complications. Lumbar radiographs were measured for changes in posterior intervertebral space height (PISH), intervertebral space foramen height (IFH), intervertebral foramen area (IFA), and area of the spinal canal (ASC). Clinical and psychological outcomes included the visual analog scale (VAS), Oswestry Disability Index (ODI), and hospital anxiety and depression scale (HADS). 35 OLIF patients were compared with 35 MISTLIF patients in L4/5 DLSS. The OLIF group had shorter bedtime, postoperative hospital stays, less intraoperative and postoperative blood loss (all P < 0.05), but had more times of intraoperative fluoroscopy, longer operative time, and higher cost (all P < 0.05). The complication rates were equivalent (OLIF vs MISTLIF: 22.86% vs 17.14%). PISH (11.94 ± 1.78 mm vs 9.42 ± 1.94 mm, P < 0.05), IFH (23.87 ± 3.05 mm vs 21.41 ± 2.95 mm, P < 0.05), and IFA (212.14 ± 51.82 mm2 vs 177.07 ± 51.73 mm2, P < 0.05) after surgery were significantly increased in the OLIF group. The ASC was increased significantly after the operation in both groups, but the ASC in the MISTLIF group was increased significantly more than that in the OLIF group (450.04 ± 66.66 mm2 vs 171.41 ± 58.55 mm2, P < 0.05). The lumbar VAS scores at 1 month (1.89 ± 0.87 vs 2.34 ± 0.84, P = 0.028) and 6 months (1.23 ± 0.97 vs 1.80 ± 0.99, P = 0.018) after operation in the OLIF group were significantly lower. There were no significant differences in lower extremity VAS and ODI scores between the two groups. Compared with MISTLIF group, HADS scores on postoperative day 3 (2.91 ± 1.46 vs 4.89 ± 1.78, P < 0.05) and prior to hospital discharge (PTD) (2.54 ± 1.38 vs 3.80 ± 1.78, P = 0.002) in the OLIF group were decreased significantly. OLIF showed more advantages of less surgical invasion, lower incidence of postoperative low back pain, faster postoperative recovery, and less anxiety compared with MISTLIF. Regardless of cost, OLIF seems to be a better option to treat mild to moderate symptomatic DLSS.

Spinal Canal Remodeling and Indirect Decompression of Contralateral Foraminal Stenosis After Endoscopic Posterolateral Transforaminal Lumbar Interbody Fusion

Objective: There is a lack of literature on indirect decompression in uniportal endoscopic posterolateral transforaminal lumbar interbody fusion (EPTLIF). Our aim is to evaluate the dimensions of the spinal canal and contralateral foramen before and after EPTLIF.Methods: This is a retrospective study of patients who underwent EPTLIF in a tertiary spine centre over a 2-year period. The cross-sectional area of the spinal canal and the contralateral foramen at the level of fusion were measured on magnetic resonance imaging scan at 1-day postoperation and at the final follow-up. Patients were grouped according to the decompression performed as per the clinician’s judgement.Results: One hundred fifty-two levels of fusion were performed in 120 patients. There was a statistically significant clinical improvement in visual analogue scale and Oswestry Disability Index scores postoperation. The measurements of the spinal canal area were 106.0 mm², 138.8 mm², and 195.5 mm²; while contralateral foraminal area were 73.2 mm², 104.4 mm², and 120.7 mm² at preoperation, 1-day postoperation, and at the final follow-up, respectively (p < 0.001). For the subgroup analyses, spinal canal area measurements for the bilateral decompression cohort (n = 35) were 57.0 mm², 123.9 mm², and 191.8 mm²; for the ipsilateral decompression cohort (n = 42) were 89.3 mm², 128.9 mm², 183.3 mm²; and for the cohort without any decompression and only cage inserted (n = 75) were 138.3 mm², 151.2 mm², and 204.1 mm² (p < 0.001). Contralateral foraminal area measurements were 73.3 mm², 106.4 mm² and 120.4 mm² in the bilateral decompression cohort; 69.5 mm², 99.0 mm², 116.9 mm² in the ipsilateral decompression cohort; and 75.1 mm², 106.5 mm², 122.9 mm² in the cohort without any decompression (p < 0.001).Conclusion: Indirect decompression of both the spinal canal and the contralateral foramen can be achieved via EPTLIF. Decompression on an asymptomatic contralateral side is not necessary.

Indirect Effects on Adjacent Segments After Minimally Invasive Transforaminal Lumbar Interbody Fusion

OBJECTIVE

To compare radiographic parameters at adjacent segments before and after minimally invasive transforaminal lumbar interbody fusion and assess relationships of radiographic changes between adjacent segments and fused level.

METHODS

Study participants included 44 patients who underwent minimally invasive transforaminal lumbar interbody fusion at L4-5 level. Radiographic parameters at adjacent segments (L3-4 and L5-S1) and clinical parameters were reviewed.

RESULTS

Postoperative dural sac area significantly increased in upper (mean change 8.05 mm2, P < 0.001) and lower (14.08 mm2, P < 0.001) adjacent segments. Significant increases in SAPD were seen in upper (0.85 mm, P < 0.001) and lower (0.66 mm, P < 0.001) adjacent segments. Ligamentum flavum thickness significantly decreased in lower adjacent segments (-0.37 mm, P = 0.006). For every 1-mm increase in fused level disc height, lower SAPD increased 0.22 mm (P = 0.04), and lower segmental angle increased 0.91° (P = 0.04). For every 1° increase in fused level segmental angle, lower dural sac area increased 1.25 mm2 (P = 0.03), and lower SAPD increased 0.12 mm (P = 0.003). The 6- and 12-month postoperative visual analog scale back and leg scores significantly decreased compared with preoperatively (back: mean change -5.98 and -6.05, P < 0.001; leg: -6.86 and -6.89, P < 0.001).

CONCLUSIONS

Performing minimally invasive transforaminal lumbar interbody fusion at the symptomatic index level does not worsen canal dimension of asymptomatic adjacent segments during short-term follow-up. It might be possible to improve canal dimension at adjacent segments by changing disc height or lordosis at the fused level via adjusting size and position of the interbody cage.

Radiological follow-up of the degenerated facet joints after lateral lumbar interbody fusion with percutaneous pedicle screw fixation: Focus on spontaneous facet joint fusion

BACKGROUND

Lateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion.

METHODS

We retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints' fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively.

RESULTS

The fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade ≧ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion.

CONCLUSIONS

Our study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.

Comparing the medium-term outcomes of lumbar interbody fusion via transforaminal and oblique approach in treating lumbar degenerative disc diseases

BACKGROUND CONTEXT

Oblique lumbar interbody fusion (OLIF) has been proven to be effective in treating lumbar degenerative disorders (LDDs) via indirect decompression. However, its superiority over transforaminal lumbar interbody fusion (TLIF) remains questionable, especially in terms of medium-term follow-up.

PURPOSE

To compare the medium-term clinical and radiological outcomes of TLIF and OLIF in treating patients with LDDs.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

Fifty-two patients treated by TLIF and forty-six patients treated by OLIF.

OUTCOME MEASURES

Clinical records including the visual analog scale (VAS) score of the lower back and leg and the Oswestry Disability Index (ODI). Radiological records including disk height (DH), lumbar lordosis (LL), segmental lordosis (SL), the cross-sectional area (CSA) of the spinal canal, and fusion rate. Surgical-related information and complications were also recorded.

METHODS

A retrospective review was performed on patients who were surgically managed for LDDs at L4-5 between 2015 and 2017 and completed at least 4 years of follow-up. A total of 98 patients were analyzed, with 46 patients treated by OLIF combined with anterolateral single screw-rod fixation (OLIF-AF group), and 52 patients treated by TLIF (TLIF group). Parameters including postoperative outcomes and perioperative complications were compared with evaluate the efficacy of the two approaches.

RESULTS

There was significantly less bleeding, surgical duration, and hospitalization in the OLIF-AF group than in the TLIF group. Significant improvements in the clinical score were achieved in both groups. However, the VAS score of the lower back was significantly higher in the TLIF group than in the OLIF-AF group throughout the whole follow-up period. Significantly higher expansion of the CSA was found in the TLIF group than in the OLIF-AF group. However, the improvements in DH, LL, and SL were significantly lower in the TLIF group. The fusion rate was significantly higher in the OLIF-AF group than in the TLIF group within 6 months postoperatively, and there was no significant difference between the two groups at the final record. No significant difference was found in the rate of overall complications between the two groups (25.0% vs. 23.9%, p=.545). The intraoperative complication rate in the TLIF group (13.5%) was slightly higher than that in the OLIF-AF group (6.5%) (p=.257). There was no significant difference in the incidence of adjacent segment disorder (ASD) between the two groups (7.7% vs. 10.9%, p=.422). Cage subsidence was slightly lower in the TLIF group (5.8%) than in the OLIF-AF group (13.0%) (p=.298).

CONCLUSIONS

Both the TLIF and OLIF-AF approaches demonstrated good medium-term outcomes in treating LDDs. Compared with TLIF, OLIF-AF showed advantages in postoperative recovery, improvement of intervertebral space and lumbar sagittal balance, and early intervertebral fusion but was associated with inferior spinal canal decompression efficacy. The two approaches shared comparable overall complication rates. However, OLIF-AF tended to have fewer intraoperative complications, and a higher incidence of subsidence.

Remodeling Pattern of Spinal Canal after Full Endoscopic Uniportal Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression: One Year Repetitive MRI and Clinical Follow-Up Evaluation

Objective: There is limited literature on repetitive postoperative MRI and clinical evaluation after Uniportal Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression. Methods: Clinical visual analog scale, Oswestry Disability Index, McNab’s criteria evaluation and MRI evaluation of the axial cut spinal canal area of the upper end plate, mid disc and lower end plate were performed for patients who underwent single-level Uniportal Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression. From the evaluation of the axial cut MRI, four types of patterns of remodeling were identified: type A: continuous expanded spinal canal, type B: restenosis with delayed expansion, type C: progressive expansion and type D: restenosis. Result: A total of 126 patients with single-level Uniportal Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression were recruited with a minimum follow-up of 26 months. Thirty-six type A, fifty type B, thirty type C and ten type D patterns of spinal canal remodeling were observed. All four types of patterns of remodeling had statistically significant improvement in VAS at final follow-up compared to the preoperative state with type A (5.59 ± 1.58), B (5.58 ± 1.71), C (5.58 ± 1.71) and D (5.27 ± 1.68), p < 0.05. ODI was significantly improved at final follow-up with type A (49.19 ± 10.51), B (50.00 ± 11.29), C (45.60 ± 10.58) and D (45.60 ± 10.58), p < 0.05. A significant MRI axial cut increment of the spinal canal area was found at the upper endplate at postoperative day one and one year with type A (39.16 ± 22.73; 28.00 ± 42.57) mm2, B (47.42 ± 18.77; 42.38 ± 19.29) mm2, C (51.45 ± 18.16; 49.49 ± 18.41) mm2 and D (49.10 ± 23.05; 38.18 ± 18.94) mm2, respectively, p < 0.05. Similar significant increment was found at the mid-disc at postoperative day one, 6 months and one year with type A (55.16 ± 27.51; 37.23 ± 25.88; 44.86 ± 25.73) mm2, B (72.83 ± 23.87; 49.79 ± 21.93; 62.94 ± 24.43) mm2, C (66.85 ± 34.48; 54.92 ± 30.70; 64.33 ± 31.82) mm2 and D (71.65 ± 16.87; 41.55 ± 12.92; 49.83 ± 13.31) mm2 and the lower endplate at postoperative day one and one year with type A (49.89 ± 34.50; 41.04 ± 28.56) mm2, B (63.63 ± 23.70; 54.72 ± 24.29) mm2, C (58.50 ± 24.27; 55.32 ± 22.49) mm2 and D (81.43 ± 16.81; 58.40 ± 18.05) mm2 at postoperative day one and one year, respectively, p < 0.05. Conclusions: After full endoscopic lumbar decompression, despite achieving sufficient decompression immediately postoperatively, varying severity of asymptomatic restenosis was found in postoperative six months MRI without clinical significance. Further remodeling with a varying degree of increment of the spinal canal area occurs at postoperative one year with overall good clinical outcomes.

Sequential MRI Changes After Lateral Lumbar Interbody Fusion in Spondylolisthesis with Mild and Severe Lumbar Spinal Stenosis

OBJECTIVE

We assessed the sequential magnetic resonance imaging changes of indirect neural decompression after minimally invasive lumbar lateral interbody fusion (LIF) combined with posterior percutaneous pedicle screw (PPS) fixation for degenerative spondylolisthesis (DS) according to the severity of preoperative lumbar spinal stenosis.

METHODS

A total of 43 patients (mean age, 68.7 years; 16 men and 27 women) with DS who had undergone LIF and closed reduction with PPS fixation were enrolled. The intervertebral levels were divided into the moderate stenosis (MS) group (preoperative cross-sectional area [CSA] of the thecal sac >50 mm²) and severe stenosis (SS) group (CSA ≤50 mm²). The CSA, ligamentum flavum thickness, and diameter of the thecal sac at the affected level were measured on cross-sectional magnetic resonance images at baseline, immediately postoperatively, and 2 years postoperatively.

RESULTS

For the 31 and 29 intervertebral levels in the MS and SS groups, the mean CSA at baseline, immediately postoperatively, and 2 years postoperatively was 76.9 mm² and 35.8 mm², 104.3 mm² and 81.4 mm², and 130.9 mm² and 105.7 mm², respectively. The mean ligamentum flavum thicknesses at 2 years postoperatively became thinner than that immediately after surgery in both groups (P < 0.01). The mean diameter of the thecal sac at 2 years was longer than that immediately after surgery in both groups (MS group, P < 0.05; SS group, P < 0.01) The expansion ratio of the CSA at 2 years postoperatively was significantly greater in the SS group than that in the MS group (P < 0.01).

CONCLUSIONS

Sequential enlargement of the spinal canal was obtained by the thinning of the ligamentum flavum after LIF and PPS fixation in patients with DS with both mild and severe stenosis. The effect of indirect neural decompression was equivalent even in those with severe lumbar spinal stenosis.

Clinical and radiological results of indirect decompression after anterior lumbar interbody fusion in central spinal canal stenosis

OBJECTIVE

Whereas the benefits of indirect decompression after lateral lumbar interbody fusion are well known, the effects of anterior lumbar interbody fusion (ALIF) have not yet been verified. The purpose of this study was to evaluate the clinical and radiological effects of indirect decompression after ALIF for central spinal canal stenosis. In this report, along with the many advantages of the anterior approach, the authors share cases with good outcomes that they have encountered.

METHODS

The authors performed a retrospective analysis of 64 consecutive patients who underwent ALIF for central spinal canal stenosis with instability and mixed foraminal stenosis between January 2015 and December 2018 at their hospital. Clinical assessments were performed using the visual analog scale score, the Oswestry Disability Index, and the modified Macnab criteria. The radiographic parameters were determined from pre- and postoperative cross-sectional MRI scans of the spinal canal and were compared to evaluate neural decompression after ALIF. The average follow-up period was 23.3 ± 1.3 months.

RESULTS

All clinical parameters, including the visual analog scale score, Oswestry Disability Index, and modified Macnab criteria, improved significantly. The mean operative duration was 254.8 ± 60.8 minutes, and the intraoperative bleeding volume was 179.8 ± 119.3 ml. In the radiological evaluation, radiological parameters of the cross-sections of the spinal canal showed substantial development. The spinal canal size improved by an average of 43.3% (p < 0.001) after surgery. No major complications occurred; however, aspiration guided by ultrasonography was performed in 2 patients because of a pseudocyst and fluid collection.

CONCLUSIONS

ALIF can serve as a suitable alternative to extensive posterior approaches. The authors suggest that ALIF can be used for decompression in central spinal canal stenosis as well as restoration of the foraminal dimensions, thus allowing decompression of the nerve roots.

Oblique Lateral Interbody Fusion versus Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spondylolisthesis: A Single-Center Retrospective Comparative Study

Objective

To compare the efficacy of oblique lateral interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF) in single-level degenerative lumbar spondylolisthesis (DLS).

Methods

A retrospective analysis of patients who underwent single-level DLS surgery in our department from 2015 to 2018 was performed. According to the surgical method, the enrolled patients were divided into two groups, namely, the OLIF group who underwent OLIF combined with percutaneous pedicle screw fixation (PPSF) and the TLIF group. Clinical outcomes included operation time, operation blood loss, postoperative drainage, hospital stay, visual analog scale (VAS) score, Oswestry disability index (ODI), and complications, and imaging outcomes included upper vertebral slip, intervertebral space height (ISH), intervertebral foramen height (IFH), intervertebral space angle (ISA), lumbar lordosis (LL), and bone fusion rate. All outcomes were recorded and analyzed.

Results

A total of 65 patients were finally included, and there were 28 patients and 37 patients in the OLIF group and the TLIF group, respectively. The OLIF group showed shorter operation time, less blood loss, less postoperative drainage, and shorter hospital stay than the TLIF group (P < 0.05). The ISH, IFH, ISA, and LL were all larger in the OLIF group at postoperative and last follow-up (P < 0.05), but the degree of upper vertebral slip was found no difference between the two groups (P > 0.05). The bone graft fusion rate of OLIF group and TLIF group at 3 months, 6 months, and last follow-up was 78.57%, 92.86%, and 100% and 70.27%, 86.49%, and 97.30%, respectively, and no significant differences were found (P > 0.05). Compared with the TLIF group, the OLIF group showed a superior improvement in VAS and ODI at 1 month, 3 months, and 6 months postoperative (P < 0.05), but no differences were found at 12 months postoperative and the last follow-up (P > 0.05). There was no significant difference in complications between the two groups, with 4 patients and 6 patients in the OLIF group and TLIF group, respectively (P > 0.05).

Conclusions

Compared with TLIF, OLIF showed the advantages of less surgical invasion, better decompression effect, and faster postoperative recovery in single-level DLS surgery.

Usefulness of Oblique Lumbar Interbody Fusion as Revision Surgery: Comparison of Clinical and Radiological Outcomes Between Primary and Revision Surgery

OBJECTIVE

Oblique lumbar interbody fusion (OLIF) is useful as surgical treatment of degenerative lumbar disease. However, revision surgery has often resulted in worse surgical outcomes than primary surgery. Thus, we compared the usefulness of OLIF as primary surgery (PS) versus revision surgery (RS).

METHODS

We retrospectively investigated 173 patients who had undergone single-level OLIF from 2016 to 2018. The radiological and clinical outcomes were compared between PS (n = 152) and RS (n = 21). The effects of RS on the clinical outcomes (Oswestry Disability Index [ODI] cutoff, 12) after surgery were investigated.

RESULTS

The ODI and visual analog scale score at 6 and 12 months after surgery was worse in the RS group than in the PS group (P < 0.05). In the RS group, the visual analog scale score for leg pain of the previous laminectomy side was worse than that of the virgin side at 6 and 12 months after surgery (P < 0.05). The disc height, ligamentum flavum, and subsidence did not differ between the 2 groups. However, the cross-sectional area enlargement differed between the 2 groups (P < 0.05). Multivariate logistic regression analysis showed that RS and severe subsidence were risk factors for differences in the ODI (P = 0.006 and P = 0.017, respectively).

CONCLUSIONS

Most radiological outcomes were similar between the RS and PS groups, with no differences in complications or the requirement for additional posterior decompression. However, OLIF resulted in relatively poor clinical outcomes when used as RS. Thus, revision spine surgery tends to result in poor outcomes compared with those of primary spine surgery; however, OLIF can be a tolerable option for revision spine surgery.

Low energy extracorporeal shock wave therapy combined with low tension traction can better reshape the microenvironment in degenerated intervertebral disc regeneration and repair

BACKGROUND

Low-tension traction is more effective than high-tension traction in restoring the height and rehydration of a degenerated disc and to some extent the bony endplate. This might better reshape the microenvironment for disc regeneration and repair. However, the repair of the combination of endplate sclerosis, osteophyte formation, and even collapse leading to partial or nearly complete occlusion of the nutrient channel is greatly limited.

PURPOSE

To evaluate the effectiveness of low-intensity extracorporeal shock wave therapy (ESWT) combined with low tension traction for regeneration and repair of moderately and severely degenerated discs; to explore the possible mechanism of action.

STUDY DESIGN

Animal study of a rat model of degenerated discs.

METHODS

A total of thirty-five 6-month old male Sprague-Dawley rats were randomly assigned to one of five groups (n=7, each group). In Group A (model group), caudal vertebrae were immobilized using a custom-made external device to fix four caudal vertebrae (Co7-Co10) whereas Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration. In Group B (experimental control group), as in Group A, disc degeneration was successfully induced after which the fixed device was removed for 8 weeks of self-recovery. The remaining three groups of rats represented the intervention Groups (C-E): after successful generation of disc degeneration in Group C (com - 4w/tra - 4w) and Group D (com - 4w/ESWT), as described for group A, low-tension traction (in-situ traction) or low-energy ESWT was administered for 4 weeks (ESWT parameters: intensity: 0.15 Mpa; frequency: 1 Hz; impact: 1,000 each time; once/week, 4 times in total); Group E (com - 4w/tra - 4w/ESWT): disc degeneration as described for group A, low-tension traction combined with low-energy ESWT was conducted (ESWT parameters as Group D). After experimentation, caudal vertebrae were harvested and disc height, T2 signal intensity, disc morphology, total glycosaminoglycan (GAG) content, gene expression, structure of the Co8-Co9 bony endplates and elastic moduli of the discs were measured.

RESULTS

After continuous low-tension traction, low energy ESWT intervention or combined intervention, the degenerated discs effectively recovered their height and became rehydrated. However, the response in Group D was weaker than in the other intervention groups in terms of restoration of intervertebral disc (IVD) height, whereas Group E was superior in disc rehydration. Tissue regeneration was evident in Groups C to E using different interventions. No apparent tissue regeneration was observed in the experimental control group (Group B). The histological scores of the three intervention groups (Groups C-E) were lower than those of Groups A or B (p<.0001), and the scores of Groups C and E were significantly lower than those of Group D (p<.05), but not Group C versus Group E (p>.05). Compared with the intervention groups (Groups C-E), total GAG content of the nucleus pulposus (NP) in Group B did not increase significantly (p>.05). There was also no significant difference in the total GAG content between Groups A and B (p>.05). Of the three intervention groups, the recovery of NP GAG content was greatest in Group E. The expression of collagen I and II, and aggrecan in the annulus fibrosus (AF) was up-regulated (p<.05), whereas the expression of MMP-3, MMP-13, and ADAMTS-4 was down-regulated (p<.05). Of the groups, Group E displayed the greatest degree of regulation. The trend in regulation of gene expression in the NP was essentially consistent with that of the AF, of which Group E was the greatest. In the intervention groups (Groups C-E), compared with Group A, the pore structure of the bony endplate displayed clear changes. The number of pores in the endplate in Groups C to E was significantly higher than in Group A (p<.0001), among which Group C versus Group D (p=.9724), and Group C versus Group E (p=.0116). There was no significant difference between Groups A and B (p=.5261). In addition, the pore diameter also increased, the trend essentially the same as that of pore density. There was no significant difference between the three intervention groups (p=.7213). It is worth noting that, compared with Groups A and B, peripheral pore density and size in Groups D and E of the three intervention groups recovered significantly. The elastic modulus and diameter of collagen fibers in the AF and NP varied with the type of intervention. Low tension traction combined with ESWT resulted in the greatest impact on the diameter and modulus of collagen fibers.

CONCLUSIONS

Low energy ESWT combined with low tension traction provided a more stable intervertebral environment for the regeneration and repair of moderate and severe degenerative discs. Low energy ESWT promoted the regeneration of disc matrix by reducing MMP-3, MMP-13, and ADAMTS-4 resulting in inhibition of collagen degradation. Although axial traction promoted the recovery of height and rehydration of the IVD, combined with low energy ESWT, the micro-nano structure of the bony endplate underwent positive reconstruction, tension in the annulus of the AF and nuclear stress of the NP declined, and the biomechanical microenvironment required for IVD regeneration and repair was reshaped.

Indirect Decompression Effect to Central Canal and Ligamentum Flavum After Extreme Lateral Lumbar Interbody Fusion and Oblique Lumbar Interbody Fusion

STUDY DESIGN

A retrospective study (level of evidence: level 4).

OBJECTIVE

To evaluate the radiographic outcomes after extreme lateral lumbar interbody fusion (XLIF) and oblique lateral lumbar interbody fusion (OLIF) procedures especially the effect of indirect decompression to the ligamentum flavum and to evaluate the effect of facet degeneration to the radiographic outcomes of these procedures.

SUMMARY OF BACKGROUND DATA

Indirect decompression via lateral lumbar interbody fusion provides spinal canal area expansion. However, the effect to the ligamentum flavum area and thickness at the operated spinal level is unclear.

METHODS

Thirty-five patients (57 lumbar levels) underwent XLIF or OLIF with percutaneous pedicle screw fixation (PPS) without direct posterior decompression were retrospectively studied. Radiographic parameters including ligamentum flavum area (LFA), ligamentum flavum thickness (LFT), cross-sectional area (CSA) of thecal sac, posterior disc height, foraminal height, cage alignment, and facet degeneration were measured on magnetic resonance image (MRI). Cage position was assessed with plain radiography.

RESULTS

All of the radiographic parameters were significantly improved. Comparing pre- and postoperative value, mean LFA decreased from 78.9 ± 24.9 mm to 66.9 ± 26.8 mm (-14.2%; P-value < 0.00625). Mean right LFT decreased from 2.9 ± 0.9 mm to 2.3 ± 0.7 (-17.0%; P-value < 0.00625). Mean left LFT decreased from 3.3 ± 1.6 mm to 2.6 ± 0.9 mm (-17.6%; P-value < 0.00625). Mean CSA of thecal sac increased from 93.1 ± 43.0 mm to 127.3 ± 52.5 mm (50.8%; P-value < 0.00625). All radiographic outcomes were not significant difference between lumbar levels that have grade 0-1 and grade 2-3 or between grade 2 and grade 3 facet degeneration.

CONCLUSION

Ligamentum flavum area and thickness were significantly reduced after lateral lumbar interbody fusion through both XLIF and OLIF. Unbuckling of the ligamentum flavum played an important role for improvement of spinal canal area after the indirect decompression.

LEVEL OF EVIDENCE

4.

Indirect decompression with lateral interbody fusion for severe degenerative lumbar spinal stenosis: minimum 1-year MRI follow-up

OBJECTIVE

The use of indirect decompression surgery for severe canal stenosis remains controversial. The purpose of this study was to investigate the efficacy of lateral interbody fusion (LIF) without posterior decompression in degenerative lumbar spinal spondylosis with severe stenosis on preoperative MRI.

METHODS

This is a retrospective case series from a single academic institution. The authors included 42 patients (45 surgical levels) who were preoperatively diagnosed with severe degenerative lumbar stenosis on MRI based on the previously published Schizas classification. These patients underwent LIF with supplemental pedicle screw fixation without posterior decompression. Surgical levels were limited to L3-4 and/or L4-5. All patients satisfied the minimum 1-year MRI follow-up. The authors compared the cross-sectional area (CSA) of the thecal sac and the clinical outcome scores (Japanese Orthopaedic Association [JOA] score) preoperatively, immediately postoperatively, and at the 1-year follow-up. Fusion status and disc height were evaluated based on CT scans obtained at the 1-year follow-up.

RESULTS

The CSA improved over time, increasing from 54.5 ± 19.2 mm2 preoperatively to 84.7 ± 31.8 mm2 at 3 weeks postoperatively and to 132.6 ± 37.5 mm2 at the last follow-up (average 28.3 months) (p < 0.001). The JOA score significantly improved over time (preoperatively 16.1 ± 4.1, 3 months postoperatively 24.4 ± 4.0, and 1-year follow-up 25.7 ± 2.9; p < 0.001). The fusion rate at the 1-year follow-up was 88.8%, and disc heights were significantly restored (preoperative, 6.3 mm and postoperative, 9.6 mm; p < 0.001). Patients showing poor CSA expansion (< 200% expansion rate) at the last follow-up had a higher prevalence of pseudarthrosis than patients with significant CSA expansion (> 200% expansion rate) (25.0% vs 3.4%, p < 0.001). No major perioperative complications were observed.

CONCLUSIONS

LIF with indirect decompression for degenerative lumbar disease with severe canal stenosis provided successful clinical outcomes, including restoration of disc height and indirect expansion of the thecal sac. Severe canal stenosis diagnosed on preoperative MRI itself is not a contraindication for indirect decompression surgery.

Decreasing thickness and remodeling of ligamentum flavum after oblique lumbar interbody fusion

PURPOSE

Ligamentum flavum is one of the structures that could compress the spinal canal. Few studies have reported atrophy of ligamentum flavum after spinal fusion. The purpose of this study was to demonstrate the reduction of ligamentum flavum size after oblique lumbar interbody fusion (OLIF) using magnetic resonance imaging (MRI).

METHOD

Seventeen patients who underwent OLIF without direct decompression were included. The MRI was obtained at the preoperative period, immediate postoperative period, and the follow-up period. Disc height (DH) was measured in plain radiograph. MRI measurements were spinal canal cross-sectional area (SCSA), ligamentum flavum thickness (LFT), ligamentum flavum area (LFA), and foraminal area (FA).

RESULTS

Mean age of the patients was 68.5 ± 10.8. Mean times between postoperative MRI and follow-up MRI were 20.2 ± 11.9 months. Mean disc height increased from 7.6 ± 1.6 to 11.6 ± 1.7 mm at an immediate postoperative period but decreased to 10.1 ± 1.6 mm during follow-up (p < 0.001). SCSA increased from 96.9 ± 54.9 to 136.0 ± 72.7 mm² and 171.4 ± 76.10 mm² during follow-up (p < 0.001). LFT decreased from 3.9 ± 1.2 to 3.2 ± 0.8 mm (17.9%) and further decreased to 2.9 ± 0.7 mm during follow-up (9.4%) (p < 0.001). LFA decreased from 97.4 ± 36.9 to 86.1 ± 36.9 mm2 (11.6%) and further decreased to 77.2 ± 32.5 mm² during follow-up (10.3%) (p = 0.001). FA increased from 69.2 ± 26.6 to 96.1 ± 23.0 mm² and increased to 112.9 ± 23.0 mm² during follow-up (p < 0.001).

CONCLUSION

OLIF could decompress the spinal canal and foraminal canal indirectly. Despite the diminishing disc height during the follow-up period, the spinal canal was further increased in size from the remodeling of the ligamentum flavum.

Indirect Decompression Using Lateral Lumbar Interbody Fusion for Restenosis after an Initial Decompression Surgery

Study Design

Retrospective comparative study.

Purpose

We compared clinical and radiographical outcomes after lumbar decompression revision surgery for restenosis by lateral lumbar interbody fusion (LLIF) and posterior lumbar interbody fusion (PLIF).

Overview of Literature

Indirect lumbar decompression with LLIF was used to treat degenerative lumbar diseases requiring neural decompression. However, only a few studies have focused on the effectiveness of this technique for restenosis after lumbar decompression.

Methods

We retrospectively investigated 52 cases involving lumbar interbody fusions for restenosis with spondylolisthesis after lumbar decompressions; these cases consisted of 15 patients who underwent indirect decompression with LLIF and posterior fixation and 37 patients who underwent the same procedure with PLIF. We compared Japanese Orthopaedic Association (JOA) scores and perioperative complications between groups. The cross-sectional areas of the thecal sac on magnetic resonance imaging were measured before, immediately after, and 2 years after surgery. We conducted statistical analyses using unpaired t -test and Fisher’s exact tests, and a p-value <0.05 was considered statistically significant.

Results

The operative time was significantly shorter in the LLIF group than in the PLIF group (115.3±33.6 min vs. 186.2±34.2 min, respectively; p<0.001). In addition, the intraoperative blood loss was significantly lower in the LLIF group than in the PLIF group (58.2±32.7 mL vs. 303.2±140.1 mL, respectively; p<0.001). We found two cases of transient lateral thigh weakness (13.3%) in the LLIF group and five cases of incidental durotomy, one case of deep infection, and one case of neurological deterioration in the PLIF group—resulting in a higher complication incidence (18.9%), although it did not reach (p=0.63). The JOA scores improved significantly in both groups.

Conclusions

Indirect decompression using LLIF provided acceptable clinical and radiographical outcomes in patients with restenosis with spondylolisthesis after lumbar decompression; no revision-surgery-specific complications were found. Our results suggest that LLIF is a safe and minimally invasive procedure for revision surgery.

Clinical Effects of Oblique Lateral Interbody Fusion by Conventional Open versus Percutaneous Robot-Assisted Minimally Invasive Pedicle Screw Placement in Elderly Patients

OBJECTIVES

To compare the clinical outcomes of percutaneous robot-assisted minimally invasive pedicle screw insertion versus freehand fluoroscopy-assisted pedicle screw insertion using a traditional open technique in elderly patients undergoing an oblique lumbar interbody fusion (OLIF) procedure.

METHODS

Based on the inclusion and exclusion criteria, 80 patients with lumbar degenerative disease who attended the spinal surgery department of the Beijing Jishuitan Hospital between January 2017 and April 2018 were enrolled in the present study. Patients were randomized 1:1 to undergo percutaneous robot-assisted minimally invasive pedicle screw insertion (experimental group, n = 40) or freehand fluoroscopy-assisted pedicle screw insertion using a traditional open technique (control group, n = 40). Outcomes were accuracy of screw placement evaluated on postoperative CT using the modified Gertzbein and Robbins scale, operative time, blood loss, postoperative drainage, lower back and leg pain evaluated using a visual analogue scale (VAS), lumbar function evaluated using the Oswestry disability index (ODI), and complication rates.

RESULTS

A total of 344 vertebral pedicle screws were inserted: 170 screws in the experimental group, and 174 screws in the control group. Accurate screw placement was significantly higher in the experimental group (98.2% [167/170]) than in the control group (93.1% [162/174]). Clinical outcomes showed significant differences between the experimental and control groups in operative time, intraoperative blood loss, and postoperative VAS for lower back pain in the immediate postoperative period.

CONCLUSION

Robot-assisted pedicle screw insertion in OLIF is an effective strategy for the management of elderly patients with lumbar degenerative diseases.

Indirect Decompression on MRI Chronologically Progresses After Immediate Postlateral Lumbar Interbody Fusion: The Results From a Minimum of 2 Years Follow-Up

MINI: On magnetic resonance imaging, indirect decompression using lateral lumbar interbody fusion and posterior fixation was confirmed immediately after surgery and also continuously progressed after surgery, particularly during the first 6 months. Thecal sac enlargement was also confirmed, and is suspected to be caused by the atrophy of the ligamentum flavum and the disc.

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

The aim of this study was to investigate radiographical changes related to indirect decompression using lateral lumbar interbody fusion (LLIF) with posterior fixation.

SUMMARY OF BACKGROUND DATA

Indirect lumbar decompression via LLIF is used to treat degenerative lumbar diseases requiring neural decompression. Although evidence suggests that thecal sac enlargement follows shortly after surgery, few studies have described the postoperative changes on MRIs.

METHODS

This study involved 102 patients who underwent indirect decompression at 136 levels, with LLIF and posterior fixation. Magnetic resonance imaging (MRIs) were collected preoperatively and several times postoperatively (over a 2-year period starting immediately after surgery). We then quantified the cross-sectional areas of the thecal sac and ligamentum flavum, as well as the anteroposterior diameter of disc bulging, and qualitatively assessed lumbar spinal stenosis according to a modified version of Schizas' classification [Grades A (mild) to C (severe)]. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) was used for the assessment of the clinical symptoms.

RESULTS

All changes were observable immediately after surgery, progressed over time, and were significantly different statistically at 2 years after surgery. The thecal sac was significantly larger (189% of preoperative; P < 0.0001), while the ligamentum flavum and disc bulge were significantly smaller [58.9% and 67.3% of preoperative (P < 0.001), respectively]. The number of patients with grade C (severe) lumbar stenosis also dropped significantly (preoperative, 17.6%; 2 years postoperative, 0%). There were no significant differences in JOABPEQ results at 6 months, 1 year, and 2 years postsurgery.

CONCLUSION

Indirect decompression produces immediate positive results that continue to improve over time. The cross-sectional area of the thecal sac doubled by 2 years after surgery, and the ligamentum flavum cross-sectional area and disc bulging both shrank significantly. At the same time, however, postoperative radiographical improvements do not appear to correlate with clinical symptoms.

LEVEL OF EVIDENCE

3.

[Guiding role of imaging evaluation in oblique lumbar interbody fusion]

OBJECTIVE

To summarize the guiding role of imaging evaluation of oblique lumbar interbody fusion (OLIF) in recent years.

METHODS

The reports of OLIF surgical imaging research at home and abroad in recent years were extensively reviewed and analyzed.

RESULTS

Preoperative imaging evaluation plays an important role in guiding the operation of OLIF, the placement of fusion Cage, the selection of indications, and the reduction of complications.

CONCLUSION

Detailed preoperative imaging evaluation can correctly estimate the indications of OLIF, and avoid the nerve, blood vessel, and muscle injuries.

Comparison of radiological changes after single- position versus dual- position for lateral interbody fusion and pedicle screw fixation

Background

There have been few comparisons between dual positions, which require a position change, and a single position, which does not require position change, and it is not clear whether there is a difference in indirect decompression achieved by the two procedures. Therefore, the purpose of this study was to compare perioperative and radiographic outcomes following lateral lumbar interbody fusion (LLIF) in two cohorts of patients who underwent surgery in a single position or dual position.

Methods

This study involved 45 patients who underwent indirect decompression at 68 levels, with LLIF and percutaneous pedicle screw (PPS) fixation for lumbar degenerative spondylolisthesis with spinal canal stenosis. Patient demographics and perioperative data were compared between two groups: patients who remained in the lateral decubitus position for pedicle screw fixation (SP group) and those turned to the prone position (DP group).

Results

A total of 26 DP and 19 SP patients were analyzed. The operation time was approximately 31 min longer for the DP group (129.7 ± 36.0 min) than for the SP group (98.4 ± 41.3 min, P < 0.01). We also evaluated the pre- and postoperative image measurements, there was no significant difference for lumbar lordosis, segmental disc angle, slipping length, and disc height between the groups. The CSA of the dural sac (DP group, from 55.3 to 78.4 mm²; SP group, from 54.7 to 77.2 mm²) and central canal diameter (DP group, from 5.9 to 7.9 mm; SP group, from 5.6 to 7.7 mm) was significantly larger after surgery in both groups. However, there were no statistically significant differences between the two groups (P = 0.684).

Conclusions

SP surgery could reduce the average surgery time by about 31 min. We found that the effect of indirect decompression by SP-PPS fixation following LLIF was considered to be a useful technique with no difference in dural sac enlargement or disc angle obtained compared with DP-PPS fixation.

Comparative Radiographic Outcomes of Lateral and Posterior Lumbar Interbody Fusion in the Treatment of Degenerative Lumbar Kyphosis

STUDY DESIGN

Retrospective case-control study.

PURPOSE

To compare surgical invasiveness and radiological outcomes between posterior lumbar interbody fusion (PLIF) and lateral lumbar interbody fusion (LLIF) for degenerative lumbar kyphosis.

OVERVIEW OF LITERATURE

LLIF is a minimally invasive interbody fusion technique; however, few reports compared the clinical outcomes of conventional PLIF and LLIF for degenerative lumbar kyphosis.

METHODS

Radiographic data for patients who have undergone lumbar interbody fusion (≥3 levels) using PLIF or LLIF for degenerative lumbar kyphosis (lumbar lordosis [LL] <20°) were retrospectively examined. The following radiographic parameters were retrospectively evaluated preoperatively and 2 years postoperatively: segmental lordotic angle, LL, pelvic tilt (PT), pelvic incidence (PI), C7 sagittal vertical axis, and T1 pelvic angle.

RESULTS

Nineteen consecutive cases with PLIF and 27 cases with LLIF were included. There were no significant differences in patients' backgrounds or preoperative radiographic parameters between the PLIF and the LLIF groups. The mean fusion level was 5.5±2.5 levels and 5.8±2.5 levels in the PLIF and LLIF groups, respectively (p=0.69). Although there was no significant difference in surgical times (p=0.58), the estimated blood loss was significantly greater in the PLIF group (p<0.001). Two years postoperatively, comparing the PLIF and LLIF groups, the segmental lordotic angle achieved (7.4°±7.6° and 10.6°±9.4°, respectively; p=0.03), LL (27.8°±13.9° and 39.2°±12.7°, respectively; p=0.006), PI-LL (19.8°±14.8° and 3.1°±17.5°, respectively; p=0.002), and PT (22.6°±7.1° and 14.2°±13.9°, respectively; p=0.02) were significantly better in the LLIF group.

CONCLUSIONS

LLIF provided significantly better sagittal alignment restoration in the context of degenerative lumbar kyphosis, with less blood loss.

Imaging Anatomic Research of Oblique Lumbar Interbody Fusion in a Chinese Population Based on Magnetic Resonance

OBJECTIVE

To provide anatomic evidence of preoperative assessment of oblique lumbar interbody fusion (OLIF) for Chinese patients.

METHODS

From the hospital picture archiving and communication system, 400 lumbar magnetic resonance imaging studies of adults performed between November 2016 and January 2017 were selected. L2-3, L3-4, L4-5, and L5-S1 transverse and sagittal images were studied, and anatomic parameters associated with OLIF surgery, including bare window and psoas window, were measured and recorded. SPSS software was used for data summarization, sorting, and analysis to explore the significance of various anatomic parameters.

RESULTS

OLIF surgical corridors to the L2-S1 discs were found in most magnetic resonance imaging scans studied. The size of the psoas affects the difficulty of psoas muscle traction. It is relatively easy to perform OLIF surgery in older women. Most of the human iliac arteries were bifurcated and aggregated in front of the L4-5 intervertebral disc. The lower the aggregate level of the common iliac vein, the less likely it was to have the OLIF surgical corridor in the L5-S1 segment. The most frequently used lengths for a lumbar interbody cage for OLIF for Chinese patients are 50 mm and 55 mm.

CONCLUSIONS

OLIF can be a good choice for lumbar intervertebral fusion, including L5-S1 segment, in most Chinese patients. Older women are likely to have more scope of OLIF surgery. As a routine preoperative examination, lumbar magnetic resonance imaging is of great importance to OLIF surgery preoperative assessment.

Resting Pain Level as a Preoperative Predictor of Success With Indirect Decompression for Lumbar Spinal Stenosis: A Pilot Study

STUDY DESIGN

Retrospective review of a single institution.

OBJECTIVE

To determine if resting leg pain level is a predictor of success for indirect decompression in the setting of lumbar spinal stenosis, with lower levels of rest pain correlating with greater likelihood of successful indirect decompression.

METHODS

Reviewed anterior or lateral lumbar interbody fusions from T12 to L5-S1 patients with a posterior-based pedicle screw-rod construct. Patients were separated into 2 groups based on a preoperative response to Oswestry Disability Index (ODI) Question 7 regarding level of pain at rest in the supine position. Responses of 0 to 2 (minimal rest pain) were group 1 (n = 54) and responses of 3 to 5 (significant rest pain) were group 2 (n = 16).

RESULTS

Preoperative difference was detected between groups 1 and 2, in ODI (38 vs 63, P < .001) and Numeric Rating Scale (NRS) back (6.8 vs 7.9, P = .023). Three-month NRS leg and back scores were significantly lower in group 1 (leg, 1.9 vs 4.8, P < .001; back, 3.5 vs 6.4, P = .001). A significant difference was further noted in the percentage decrease in NRS leg and back scores from pre- to 3 months postoperatively between groups 1 and 2 (leg, 68.4% vs 22.7%, P < .001; back, 40.0% vs 7.4%, P = .012). Group 1 reached minimal clinically important difference for leg pain more often than group 2 (83.3% vs 43.8%, P = .001).

CONCLUSION

Preoperative assessment of rest pain level in the supine position has a significant association with reduction in NRS leg and back scores in patients undergoing indirect decompression for lumbar spinal stenosis. This tool may successfully indicate which patients will be candidates for indirect decompression with interbody fusion from an anterior or lateral approach.

Pneumomediastinum and pneumopericardium as rare complications after retroperitoneal transpsoas lateral lumbar interbody fusion surgery: A case report

RATIONALE

Pneumomediastinum and pneumopericardium refer to conditions in which air exists within the mediastinum and pericardium, respectively. There is the communication between the mediastinum, pericardium, and retroperitoneum. We present the first report of rare complications (pneumomediastinum and pneumopericardium) after retroperitoneal transpsoas lateral lumbar interbody fusion (LLIF) surgery.

PATIENT CONCERNS

A 73-year-old female who underwent LLIF using the retroperitoneal approach complained of dysphagia but no other abnormal symptom after surgery.

DIAGNOSIS AND INTERVENTIONS

A plain chest radiograph (CXR) taken immediately the following surgery did not show any unusual findings but CXR took on postoperative day (POD) 1 indicated pneumopericardium and pneumomediastinum with abnormal air density along the pericardium and mediastinum with subdiaphragmatic air density. A chest computed tomography revealed bilateral pleural effusion and abnormal air density (pneumopericardium and pneumomediastinum) connected to a large amount of air around the aorta and retroperitoneal space (pneumoretroperitoneum).

OUTCOMES

The patient complained of no unusual symptom and the CXR on POD 6 indicated that no air density surrounding the mediastinum and pericardium was found.

LESSONS

Pneumomediastinum and pneumopericardium should be considered possible complications of LLIF using retroperitoneal transpsoas approach. Such a condition may progress to fatal conditions without early recognition and rapid management.