Is Direct Decompression Necessary for Lateral Lumbar Interbody Fusion (LLIF)? A Randomized Controlled Trial Comparing Direct and Indirect Decompression With LLIF in Selected Patients

OBJECTIVE

To compare the clinical and radiographic outcomes following lateral lumbar interbody fusion (LLIF) between direct and indirect decompression in the treatment of patients with degenerative lumbar diseases.

METHODS

Patients who underwent single-level LLIF were randomized into 2 groups: direct decompression (group D) and indirect decompression (group I). Clinical outcomes including the Oswestry Disability index and visual analogue scale of back and leg pain were collected. Radiographic outcomes including cross-sectional area (CSA) of thecal sac, disc height, foraminal height, foraminal area, fusion rate, segmental, and lumbar lordosis were measured.

RESULTS

Twenty-eight patients who met the inclusion criteria were eligible for the analysis, with a distribution of 14 subjects in each group. The average age was 66.1 years. Postoperatively, significant improvements were observed in all clinical parameters. However, these improvements did not show significant difference between both groups at all follow-up periods. All radiographic outcomes were not different between both groups, except for the increase in CSA which was significantly greater in group D (77.73 ± 20.26 mm2 vs. 54.32 ± 35.70 mm2, p = 0.042). Group I demonstrated significantly lower blood loss (68.13 ± 32.06 mL vs. 210.00 ± 110.05 mL, p < 0.005), as well as shorter operative time (136.35 ± 28.07 minutes vs. 182.18 ± 42.67 minutes, p = 0.002). Overall complication rate was not different.

CONCLUSION

Indirect decompression through LLIF results in comparable clinical improvement to LLIF with additional direct decompression over 1-year follow-up period. These findings suggest that, for an appropriate candidate, direct decompression in LLIF might not be necessary since the ligamentotaxis effect achieved through indirect decompression appears sufficient to relieve symptoms while diminishing blood loss and operative time.

Intervertebral disc human nucleus pulposus cells associated with back pain trigger neurite outgrowth in vitro and pain behaviors in rats

Low back pain (LBP) is often associated with the degeneration of human intervertebral discs (IVDs). However, the pain-inducing mechanism in degenerating discs remains to be elucidated. Here, we identified a subtype of locally residing human nucleus pulposus cells (NPCs), generated by certain conditions in degenerating discs, that was associated with the onset of discogenic back pain. Single-cell transcriptomic analysis of human tissues showed a strong correlation between a specific cell subtype and the pain condition associated with the human degenerated disc, suggesting that they are pain-triggering. The application of IVD degeneration-associated exogenous stimuli to healthy NPCs in vitro recreated a pain-associated phenotype. These stimulated NPCs activated functional human iPSC-derived sensory neuron responses in an in vitro organ-chip model. Injection of stimulated NPCs into the healthy rat IVD induced local inflammatory responses and increased cold sensitivity and mechanical hypersensitivity. Our findings reveal a previously uncharacterized pain-inducing mechanism mediated by NPCs in degenerating IVDs. These findings could aid in the development of NPC-targeted therapeutic strategies for the clinically unmet need to attenuate discogenic LBP.

An Expanded Surgical Corridor of Oblique Lateral Interbody Fusion at L4-5: A Magnetic Resonance Imaging Study

OBJECTIVE

We introduced a new preoperative method, the "expanded surgical corridor," to evaluate the actual safety corridor, which may expand the possibility of performing oblique lateral interbody fusion (OLIF).

METHODS

Axial T2-weighted magnetic resonance images at the L4-5 disc level of 511 lumbar degenerative disease patients was evaluated. The distance between the medial edge of the left-sided psoas muscle and the major artery was measured as the conventional surgical corridor (CSc). The distance between the major vein and lumbar plexus was measured as the expanded surgical corridor (ESc).

RESULTS

The mean CSc and ESc were 13.9 ± 8.20 and 37.43 ± 10.1 mm, respectively. No surgical corridor was found in 7.05% of CSc and 1.76% of ESc, small corridor ( ≤ 1 cm) was found in 27.40% of CSc and 0.59% of ESc, moderate corridor (1-2 cm) was found in 42.07% of CSc and 1.96% of ESc, and large corridor ( > 2 cm) was found in 23.48% of CSc and 95.69% of ESc. A total of 33.83% (45 of 133) of whom were preoperatively categorized as having a limited surgical corridor by conventional measurement, underwent OLIF L4-5 successfully.

CONCLUSION

By using the ESc, only 2.35% were categorized as having a limited surgical corridor. The other 97.65% of the patients had an approachable corridor that could be successfully operated by experienced spine surgeons who employ meticulous surgical dissection and thorough understanding of the anatomical structures. The ESc may represent true accessibility to the disc space for OLIF, particularly at the L4-5 level.

Should a Narrow Corridor Be a Contraindication for Performing Oblique Lateral Interbody Fusion Procedure or Not?

STUDY DESIGN

Retrospective study.

OBJECTIVES

We investigated the effect of corridor width on the postoperative outcomes of patients who underwent the OLIF procedure.

METHODS

Patients who underwent OLIF surgery, which included L4-5, between 2015 and 2021 were retrospectively studied. The patients were divided into three groups by the width of the corridor: not more than 10 mm, between 10 and 20 mm, and 20 mm or more. We compared clinical and radiographic outcomes and complications between these groups.

RESULTS

A total of 81 patients were included. There were no significant differences in VAS leg and back pain scores, ODI scores, or complications between each group. The radiographic findings, including cage position, anterior and posterior disc height, segmental Cobb angle, and foraminal height, also showed no significant differences between each group. The only radiographic finding that showed a significant difference between each group was the angle of the cage. We found significantly less degree of angle in the wider than 20 mm group when compared to the other two groups. (P-value = .01). There was no recorded incidence of major vascular complications.

CONCLUSIONS

The width of oblique corridor does not affect clinical outcomes, complications, or radiographic findings, including position of the cage, anterior and posterior disc height, segmental angle, and foraminal height after OLIF procedure, including L4-5 level. Thus, the OLIF procedure can be performed safely even in patients with limited oblique corridors, especially at L4-5.

Minimally Invasive Transforaminal Lumbar Interbody Fusion: Strategies for Creating Lordosis with a Posterior Approach

The purpose of this article is to review the outcomes concerning lumbar lordosis restoration after the MIS-TLIF and to present strategies to create lumbar lordosis by using this MIS posterior approach. MIS-TLIF is an effective MIS lumbar interbody fusion that can achieve lumbar lordosis restoration. Several crucial steps aid in this sagittal profile correction during the MIS-TLIF, including the appropraite prone positioning, optimizing disc space preparation, maximizing disc space height, anterior interbody cage placement, and reducing the spondylolisthesis.

Comparing Efficacy of Lumbar Disc Space Preparation via an Anterior-to-Psoas Approach Between Intraoperative Conventional Fluoroscopy and Computed Tomographic-Based Navigation System: A Cadaveric Study

OBJECTIVE

To compare the efficacy of intervertebral disc space preparation via an anterior-to-psoas (ATP) approach using conventional fluoroscopy (Flu) and computer tomography (CT)-based navigation by evaluating the disc remaining area.

METHODS

We equally assigned 24 lumbar disc levels from 6 cadavers into Flu and CT-based navigation (Nav) groups. Two surgeons performed disc space preparation using the ATP approach in both groups. Digital images of each vertebral endplate were obtained, and the remaining disc tissue was calculated in total and in quadrants. Operative time, number of attempts at disc removal, endplate violation area, number of endplate violation segments, and access angle were recorded.

RESULTS

The overall percentage of remaining disc tissue was significantly less in the Nav group than in the Flu group (32.7% vs. 43.3% respectively, P < 0.001). A significant difference was found in the posterior-ipsilateral (4.2% vs. 7.1%, P = 0.005) and posterior-contralateral (6.1% vs. 10.9%, P = 0.002) quadrants, respectively. No significant between-group difference was found concerning operative time, number of attempts at disc removal, endplate violation area, number of endplate violation segments, or access angle.

CONCLUSIONS

Intraoperative CT-based navigation may improve vertebral endplate preparation quality for an ATP approach, especially in the posterior quadrants. This technique may offer an effective alternative disc space and endplate preparation methods and may help enhance the fusion rates.

Perioperative Intravenous Nefopam on Pain Management and Ambulation after Open Spine Surgery: A Randomized Double-Blind Controlled Study

STUDY DESIGN

This was a randomized double-blind controlled study.

PURPOSE

This study was designed to evaluate the effects of intravenous nefopam regarding its ability to reduce morphine consumption and postoperative pain and improve recovery in patients undergoing open spine surgery.

OVERVIEW OF LITERATURE

Multimodal analgesia, including nonopioid medications, is essential for pain management in spine surgery. Evidence regarding the use of intravenous nefopam in open spine surgery as part of enhanced recovery after surgery is lacking.

METHODS

In this study, 100 patients undergoing lumbar decompressive laminectomy with fusion were randomized into two groups. The nefopam group received 20-mg intravenous nefopam diluted in 100-mL normal saline intraoperatively, followed by 80-mg nefopam diluted in 500-mL normal saline, administered as a continuous infusion postoperatively for 24 hours. The control group received an identical volume of normal saline. Postoperative pain was managed using intravenous morphine via patient-controlled analgesia. Morphine consumption in the first 24 hours was recorded as the primary outcome. Secondary outcomes, including postoperative pain score, postoperative function, and length of hospital stay (LOS), were assessed.

RESULTS

No statistically significant differences in the total morphine consumption and postoperative pain score in the first 24 hours postoperatively between the two groups. At the post-anesthesia care unit (PACU), the nefopam group demonstrated lower pain scores while at rest (p =0.03) and upon movement (p =0.02) than the normal saline group. However, the severity of postoperative pain between the two groups was similar from postoperative day 1 to day 3. LOS was significantly shorter in the nefopam group than in the control group (p <0.01). The time to first sitting and walking and PACU discharge between the two groups were comparable.

CONCLUSIONS

Perioperative intravenous nefopam demonstrated significant pain reduction during the early postoperative period and shortened LOS. Nefopam is considered safe and effective as a part of multimodal analgesia in open spine surgery.

Lumbar sympathetic chain tract and mobility of oblique lumbar interbody fusion approach: a cadaveric study

OBJECTIVES

To assess lumbar sympathetic chain (LSC) relation to the surgical corridor for oblique lumbar approach and the ability to mobilize the LSC.

METHODS

Forty-three cadavers were included. Left-sided anterior retroperitoneal approach was performed in a supine position. Distance between the great vessels and psoas muscle (oblique corridor) and distance between great vessels and LSC at L2/3, L3/4, and L4/5 disc levels were measured. Mobilization of LSC at each disc level was done either close to or away from the psoas muscle and each mobilization distance was measured.

RESULTS

The presence rates of LSC in oblique corridor were 19.5%, 43%, and 75.7% at L2/3, L3/4, and L4/5 levels, respectively. At L2/3 disc level, mean distance between psoas muscle and LSC and its mobility were 0.61±1.31 mm, and 2.72±1.24 mm, respectively. At L3/4 disc level, mean distance between psoas muscle and LSC and its mobility were 1.72±2.53 mm, and 3.11±1.02 mm, respectively. At L4/5 disc level, mean distance between psoas muscle and LSC and its mobility were 2.94±3.52 mm, and 2.53±1.03 mm, respectively. The mean width of corridor of L2/3, L3/4, and L4/5 were 10.73±5.82, 12.63±5.02, and 15.43±6.31 mm, respectively.

CONCLUSION

The LSC tract usually lies in the oblique corridor in L4/5 but keeps decreasing in prevalence when approaching L3/4 and L2/3 levels. It can be mobilized a few millimeters close to or away from the psoas muscle. Care should be taken to prevent LSC injury, particularly when the LSC needs to be retracted along with the psoas muscle.

Comparative outcome of lidocaine versus bupivacaine for cervical medial branch block (CMBB) in chronic cervical facet arthropathy: a randomized double-blind study

OBJECTIVE

This study evaluated the effect of prolonged concordant response and functional clinical improvement between lidocaine and bupivacaine for cervical medial branch block (CMBB) in chronic cervical facet syndrome.

METHODS

Sixty-two patients diagnosed with chronic cervical facet syndrome were randomized into either lidocaine or bupivacaine groups. The therapeutic CMBB was performed under ultrasound guidance. Either 2% lidocaine or 0.5% bupivacaine with a volume of 0.5-1 ml per level, according to the patient's pain symptoms. The patients, pain assessor, and pain specialist were blinded. The primary outcome was the duration of pain reduction by at least 50%. The numerical rating scale (NRS) of 0-10 and the Neck Disability Index (NDI) questionnaire were recorded.

RESULTS

There was no significant difference in the duration of 50% and 75% pain reduction and NDI between the lidocaine and bupivacaine groups. Lidocaine provided significant pain reduction up to 16 weeks (P<0.05) and significant improvement in neck functional outcomes up to 8 weeks (P<0.01) compared to the baseline. Whist bupivacaine yielded significant pain alleviation for up to 8 weeks for pain upon neck mobilization (P<0.05) and demonstrated notable improvement in neck function up to 4 weeks (P<0.01) compared to the baseline.

CONCLUSION

CMBB using lidocaine or bupivacaine provided clinical benefits in prolonged analgesic effect and improving neck functions for chronic cervical facet syndrome. Lidocaine illustrated better performance and could be considered a local anesthetic of choice regarding the prolonged concordance response.

Biomechanical Comparison Between Posterior Long-Segment Fixation, Short-Segment Fixation, and Short-Segment Fixation With Intermediate Screws for the Treatment of Thoracolumbar Burst Fracture: A Finite Element Analysis

BACKGROUND

Posterior long-segment (LS) fixation, short-segment (SS) fixation, and short segment fixation with intermediate screws (SI) have shown good outcomes for the treatment of thoracolumbar burst fractures. However, limited data compared the biomechanical properties between LS fixation and SI. The purpose of this study was to compare the von Mises stresses on the pedicular screw system and bone between posterior LS fixation, SS fixation, and SI for the treatment of thoracolumbar burst fracture.

MATERIALS AND METHODS

The finite element model of thoracolumbar spines from T11 to L3 was created based on the computed tomography image of a patient with a burst fracture of the L1 vertebral body. The models of pedicular screws, rods, and locking nuts were constructed based on information from the manufacturer. Three models with different fixation configurations-that is, LS, SS, and SI-were established. The axial load was applied to the superior surface of the model. The inferior surface was fixed. The stress on each screw, rod, and vertebral body was analyzed.

RESULTS

The motion of the spine in SS (0.5 mm) and SI (0.9 mm) was higher than in LS (0.2 mm). In all models, the lowest pedicle screws are the most stressed. The stress along the connecting rods was comparable between SI and LS (50 MPa). At the fracture level, stress was found at the pedicles and vertebral bodies in SI. There was relatively little stress around the fractured vertebral body in LS and SS.

CONCLUSIONS

Posterior SI preserves more spinal motion than the LS. In addition, it provides favorable biomechanical properties than the SS. The stress that occurred around the pedicle screws in SI was the least among the 3 constructs, which might reduce complications such as implant failure. SI produces more stress in the fractured vertebral body than LS and SS, which could potentially aid in bone healing according to the Wolff law.

CLINICAL RELEVANCE

SI has proved to be a biomechanically favorable construct and helps preserve the spinal motion segment. It could be an alternative surgical option for treating patients who present with thoracolumbar burst fractures.

LEVEL OF EVIDENCE: 5

Ultrasound-guided pulsed radiofrequency of cervical nerve root for cervical radicular pain: a prospective randomized controlled trial

BACKGROUND CONTEXT

Pulsed radiofrequency (PRF) on cervical dorsal root ganglion (DRG) for pain management in cervical radicular pain is mainly performed via a transforaminal approach under fluoroscopic guidance. Ultrasound-guidance periradicular cervical nerve root intervention raises concern about the neuromodulatory effect. This study aims to evaluate the effectiveness and duration of pain relief between PRF treatment and steroid injection on the cervical nerve roots.

PURPOSE

To evaluate the efficacy of pulsed radiofrequency for cervical radicular pain.

STUDY DESIGN

A prospective, double-blinded, randomized controlled clinical trial PATIENT SAMPLE: Patients who underwent ultrasound-guided periradicular cervical nerve root PRF or steroid injection from January 2020 to May 2021 at King Chulalongkorn Memorial Hospital (KCMH), Bangkok, Thailand.

OUTCOME MEASURES

The primary outcome was the pain score at 3 months postprocedure. The secondary outcomes were the duration of pain relief of at least 50%, pain scores at other time points after pain intervention, the amount of rescue pain medications, procedural time, and complications.

METHOD

Forty-two patients who presented with chronic cervical radicular pain were prospectively randomized into the PRF and steroid groups. Patients in the PRF group received PRF treatment at 42^°C for 4 minutes, followed by the injection of 2% lidocaine 1.5 mL and dexamethasone 10 mg to the targeted cervical nerve root. The steroid group received the same injectate. Patients and pain assessors were blinded. The numerical rating scale (NRS) and the Neck Disability Index (NDI) questionnaires were used for pain intensity and neck functional assessment before and after the procedure. Pain reduction was recorded up to a 9-month follow-up.

RESULTS

Data analysis was obtained from 20 and 21 patients receiving PRF and steroid treatment, respectively. At 3-month postprocedure, there were 70% of patients in the PRF group reported 50% pain reduction compared with 23.8% of patients in the steroid group (p<.01). Moreover, patients in the PRF group had significantly less pain (NRS 2.8±2.7) compared with patients in the steroid group (NRS 5.5±2.6) (p=.01). The neck disability index demonstrated significant improvement at 3 and 6 months (p<.01) after PRF treatment compared with steroid injection alone. The duration, in which pain relief was at least 50%, was significantly longer in patients who received PRF treatment (6.0±4.1 months) compared with those in the steroid group (2.3±2.1 months) (p<.01).

CONCLUSION

Ultrasound-guided periradicular cervical nerve root PRF exhibited a neuromodulatory effect and was considered effective for patients with cervical radicular pain. It provided a longer duration of pain relief and improvement of neck function for up to 6 months.

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.

Surgical Outcomes of Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Surgical Microscope vs Surgical Loupes: A Comparative Study

BACKGROUND

Minimally invasive transforaminal interbody fusion (MIS-TLIF) is an effective procedure for lumbar spine diseases. The procedure can be done using a surgical microscope (SM) or surgical loupes (SL) magnification. However, there are no studies that compared outcomes between using these 2 magnifying devices in the MIS-TLIF procedure. The purpose of this study was to compare clinical outcomes, perioperative complications, and radiographic parameters of MIS-TLIF using SM compared with SL magnification.

METHODS

We included all patients undergoing 1-level MIS-TLIF between January 2017 and December 2019. Type of magnification (SM vs SL), operative time, blood loss, perioperative complications, cross-sectional area of the spinal canal, and fusion rates were analyzed. Clinical outcomes measurement using the visual analog scale (VAS) and Oswestry Disability Index (ODI) were compared between groups.

RESULTS

A total of 100 patients had underwent MIS-TLIF (SM group: 62; SL group: 38). Operative time (SM: 182.7 ± 41.5 vs SL: 165.6 ± 32.6 minutes, P = 0.043) was significantly shorter in the SL group, with a mean difference of 17.2 minutes and a 10.4% increase in operative time between SL and SM. Blood loss (SM: 187.4 ± 176.4 vs SL: 215.6 ± 99.4 mL, P = 0.36) was not different between groups, with a mean difference of 28.2 mL. Both the SM group and SL group demonstrated no significant differences in improvement from baseline in VAS back, VAS legs, ODI score, and cross-sectional area of the spinal canal. There was also no significant difference in complication rates and fusion rates between groups.

CONCLUSIONS

Our study found no difference between intraoperative use of SL compared with SM in clinical outcomes through the 12-month follow-up timepoint. However, the use of SM resulted in an increased average operative time of 17 minutes compared with the SL group.

CLINICAL RELEVANCE

Intraoperative use of SM and SL magnification in MIS-TLIF provides similar outcomes except prolonged operative time in the SM group.

LEVEL OF EVIDENCE: 3

Analgesic Effect of Intravenous Nefopam for Postoperative Pain in Minimally Invasive Spine Surgery: A Randomized Prospective Study

Study Design

Randomized double-blind control study.

Purpose

To evaluate the effects of nefopam on reducing morphine consumption and postoperative pain in patients undergoing minimally invasive spine surgery (MISS) and to evaluate its effects on enhanced recovery after spine surgery.

Overview of Literature

Enhanced recovery after surgery (ERAS) has become a major goal for spine surgery. Multimodal pain management combining non-opioid analgesics is a key element of this. However, there is little evidence regarding the use of nefopam in spine surgery as part of an ERAS protocol.

Methods

One hundred patients undergoing MISS were randomized into two groups. Patients in the nefopam group received 20 mg of intravenous nefopam diluted in 100 mL of normal saline intraoperatively, followed by 80 mg of nefopam diluted in 500 mL of normal saline, given as a continuous infusion postoperatively for 24 hours. The control group received an identical volume of normal saline. Postoperative pain was managed by patient-controlled analgesia in the form of intravenous morphine. Morphine consumption in the first 24 hours was recorded as a primary outcome. Secondary outcomes regarding ERAS were also collected.

Results

There were no significant differences in either total morphine consumption or postoperative pain score in the first 24 hours postoperatively between patients receiving nefopam and the control group. Morphine consumption in patients receiving nefopam was 13.54±10.64 mg compared with 15.86±16.2 mg in the control group (p=0.41). Time to postanesthetic care unit discharge, times to first sitting and walking, length of hospital stay, as well as duration of Foley catheter use and time until drain removal were also similar. There were no serious adverse effects of nefopam compared with normal saline.

Conclusions

Nefopam did not significantly reduce opioid consumption or postoperative pain score. Adding nefopam as part of multimodal analgesia did not show beneficial effects for enhancing recovery after spine surgery.

Clinical and Radiographic Comparisons among Minimally Invasive Lumbar Interbody Fusion: A Comparison with Three-Way Matching

Study Design

Retrospective cohort study.

Purpose

To compare clinical and radiographic outcomes among minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), extreme lateral lumbar interbody fusion (XLIF), and oblique lateral lumbar interbody fusion (OLIF) techniques.

Overview of Literature

To date, there are many reports comparing outcomes between MIS-TLIF and XLIF, MIS-TLIF and OLIF, or XLIF and OLIF procedures. However, there are no previous studies comparing clinical and radiographic outcomes among all these three techniques.

Methods

Data from patients who underwent minimally invasive (MI) fusion surgery for lumbar degenerative diseases at L4-L5 level was analyzed. Thirty patients each from MIS-TLIF, XLIF, and OLIF groups were recruited for propensity score matching. Visual Analog Scale (VAS) of the back and legs and Oswestry Disability Index (ODI) were evaluated preoperatively and at 1, 3, and 6 months and 1 year postoperatively. Radiographic outcomes were also compared. The fusion rate was evaluated at 1 year after surgeries.

Results

The clinical outcomes were significantly improved in all groups. The disk height was significantly restored in all groups postoperatively, which was significantly more improved in XLIF and OLIF than MIS-TLIF group (p<0.001). The axial canal area was significantly increased more in MIS-TLIF versus XLIF and OLIF (p<0.001). The correction of lumbar lordotic angle and segmental sagittal angle were similar among these techniques. OLIF and XLIF groups showed less blood loss and shorter hospital stays than MIS-TLIF group (p<0.001). There was no significant difference in fusion rate among all groups.

Conclusions

MIS-TLIF, XLIF, and OLIF facilitated safe and effective MI procedures for treating lumbar degenerative diseases. XLIF and OLIF can achieve clinical outcomes equivalent to MIS-TLIF by indirect decompression. XLIF and OLIF showed less blood loss, shorter hospital stays, and better disk and foraminal height restorations. In single-level L4-5, the restoration of sagittal alignment was similar between these three techniques.

Risk factors for polyetheretherketone cage subsidence following minimally invasive transforaminal lumbar interbody fusion

BACKGROUND

Interbody cage subsidence is a postoperative complication leading to poor outcomes after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). This study aimed to identify risk factors of cage subsidence in lumbar spinal diseases after MIS-TLIF using polyetheretherketone (PEEK) cage.

METHODS

In this retrospective cohort study, plain radiographs and three-dimensional computed tomography (3D-CT) performed 12 months after MIS-TLIF were evaluated, and the risk of cage subsidence was calculated with odds ratio (OR), confidence interval (CI), and logistic regression analysis.

RESULTS

A total of 114 patients (mean age, 65 years) and 135 levels were included in this study: 80 (59.3%) with and 55 (40.7%) without cage subsidence. Multifidus atrophy showed the strongest association with PEEK cage subsidence (p < 0.001). Compared to those with normal mass, the odds of PEEK cage subsidence were 76.0 (95% CI: 3.9-1472.9) for severe atrophy. The factors significantly associated with cage subsistence were posterior cage position (OR = 4.2; p = 0.005), cage height ≥ 12 mm (OR = 7.6; p = 0.008), use of an autograft mixed with demineralized bone matrix (DBM) (OR = 5.8; p = 0.002), body mass index (BMI) > 27.5 kg/m² (OR = 4.2; p = 0.03), and titanium-coated PEEK (Ti-PEEK) cage-type (OR = 38.4, p = 0.02).

CONCLUSIONS

In MIS-TLIF with a PEEK cage, the factors associated with an increased risk of cage subsidence were higher BMI, increased severity of multifidus muscle atrophy, Ti-coated PEEK cage-type, cage height ≥ 12 mm, use of DBM mixed autograft, and posterior cage position.

Is Unilateral Minimally Invasive Transforaminal Lumbar Interbody Fusion Sufficient in Patients with Claudication? A Comparative Matched Cohort Study

OBJECTIVE

To evaluate clinical and radiologic outcomes between bilateral decompression using the over-the-top technique (group 1) and unilateral decompression (group 2) in patients with claudication who underwent minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

We enrolled patients with claudication who underwent MIS-TLIF from January 2017 to June 2019. Visual analog scale (VAS) scores and Oswestry Disability Index (ODI), walking distance, and perioperative outcomes were compared between groups. Preoperative and 3-month postoperative magnetic resonance imaging assessed changes in canal cross-sectional area, foraminal height, and lateral recess area.

RESULTS

Sixty-five consecutive patients with ≥1 year of follow-up were enrolled. VAS scores and ODI were not significantly different between groups (VAS and ODI, respectively, at 1 month follow-up, P = 0.62 and 0.88; 3 months follow-up, P = 0.96 and 0.53; 6 months follow-up, P = 0.10 and 0.85; and 12 months follow-up, P = 0.10 and 0.66). Operative time and blood loss between groups was not statistically significant (P = 0.43 and P = 0.55). There was also no difference in the length of hospital stay (P = 0.24). Canal dimensions increased in each group without significant differences between groups (cross-sectional area, P = 0.92; foraminal height [approach and contralateral side, respectively], P = 0.62 and 0.66; and lateral recess area [approach and contralateral side, respectively], P = 0.68 and 0.50).

CONCLUSIONS

A unilateral approach with ipsilateral side direct decompression and contralateral indirect decompression in MIS-TLIF is sufficient for early clinical improvement in patients with claudication.

Minimally Invasive Percutaneous Modified Iliac Screw Placement Using Intraoperative Navigation: A Technical Note

OBJECTIVE

The modified iliac screw fixation technique was proposed to be an interesting alternative option for spinopelvic fixation. In this study, we describe a new minimally invasive technique for percutaneous placement of modified iliac screws.

METHODS

A 64-year-old man with ankylosing spondylitis suffered from a 3-column fracture at the L5 vertebra without any neurologic deficit. We performed percutaneous pedicle screw fixation from L2 to S1 with additional modified iliac screws augmentation using an intraoperative navigation. We inserted both S1 pedicle screw and modified iliac screw within a stab incision on each side of the patient's back without using rod connector.

RESULTS

The patient's severe low back pain subsided on the day following the operation. There was no clinical low back pain at 2-week follow-up. The 1-year follow-up x-ray showed that the fracture was healed successfully without signs of screw loosening or breakage.

CONCLUSIONS

The modified iliac screws can be placed safely via percutaneous approach with an intraoperative image guidance. By using this new technique, surgeons can easily adjust the screw head to align with S1 pedicle screw via the same small incision. The rod connectors are not necessary for this technique. This method also prevents the acute angle that can develop between the screw head and shaft of the screw, which is typically found in S2 alar-iliac screw technique.

Anatomical study of quadriceps tendon for anterior cruciate ligament reconstruction

Background

The quadriceps tendon is a promising alternative graft choice for anterior cruciate ligament (ACL) reconstruction. Morphology of the graft directly affects the biomechanical properties. However, a few studies are evaluating the anatomical structures of quadriceps tendon as a graft in Asian population.

Objective

To define the anatomical structures of quadriceps tendon as a graft for ACL reconstruction.

Methods

Forty-nine quadriceps tendons were dissected and analyzed. Measurements were also done including length, width, and thickness.

Results

The maximum length of superficial quadriceps tendon was 63.2 ± 12.5 mm (range 37.6–83.4). The maximum length of tendon at the deepest part was 57.2 ± 11.5 (range 30.9–83.4). The maximum length of quadriceps tendon was located at 61.4% ± 13% (range 31.8–83.6) from medial edge of the patella insertion (approximately 5 mm lateral from the center of quadriceps tendon insertion). The width of quadriceps tendon at patella insertion was 42.4 ± 3.8 mm (range 33.8–50.5). The thickness of quadriceps tendon at its maximum length on patella insertion was 6.9 ± 2.0 mm (range 1.5–9.5). Positive correlation between the height of cadaver and the maximum length of quadriceps tendon was noted.

Conclusions

The maximum length of quadriceps tendon was located 5 mm lateral from the center of quadriceps tendon insertion. Thus, we recommend marking midline of the quadriceps tendon insertion as a medial border of the harvested graft to get maximum length of the graft. Graft length measurement using superficial anatomy should be cautioned because graft shortening might occur.