Mini-open lateral retroperitoneal lumbar spine approach using psoas muscle retraction technique. Technical report and initial results on six patients

New Axially Expandable Oblique Cage Designed for Anterior to Psoas (ATP) Approach: Indications-Surgical Technique and Clinical-Radiological Outcomes in Patients with Symptomatic Degenerative Disc Disease

Background: Standard oblique cages cannot cover endplates side-to-side, which is an important biomechanical factor for reducing the risk of cage subsidence and for restoring correct segmental lordosis. The aim of this study is to evaluate the radiological and clinical results of a new oblique lumbar interbody fusion (OLIF) axially expandable cage. Methods: This is a prospective observational case-control study. From March 2018 to June 2020, 28 consecutive patients with lumbar degenerative disease underwent an ATP approach, with the insertion of a new axially expandable cage, which was used as a stand-alone procedure or followed by posterior percutaneous pedicle fixation. Results: Twenty-eight patients in both groups met the inclusion criteria. The mean follow-up time was 31.2 months (range of 13-37). The clinical results were not significantly different, although in the control group, two major intraoperative complications were recorded, and slight improvements in ODI and SF-36 scores were observed in the study group. The radiological results showed a less frequent incidence of subsidence and a higher rate of fusion in the study group compared to controls. Conclusions: The axially expandable oblique cage for lumbar inter body fusion, specifically designed for the ATP approach, represents an innovation and a technical improvement. The insertion and the axial expansion technique are safe and easy. The large footprint could obtain solid and effective arthrodesis, potentially reducing the risk of subsidence.

The anatomical positioning change of retroperitoneal organs in prone and lateral position: an assessment for single-prone position lateral lumbar surgery

PURPOSE

There are reports that performing lateral lumbar interbody fusion (LLIF) in a prone, single position (single-prone LLIF) can be done safely in the prone position because the retroperitoneal organs reflect anteriorly with gravity. However, only a few study has investigated the safety of single-prone LLIF and retroperitoneal organ positioning in the prone position. We aimed to investigate the positioning of retroperitoneal organs in the prone position and evaluate the safety of single-prone LLIF surgery.

METHODS

A total of 94 patients were retrospectively reviewed. The anatomical positioning of the retroperitoneal organs was evaluated by CT in the preoperative supine and intraoperative prone position. The distances from the centre line of the intervertebral body to the organs including aorta, inferior vena cava, ascending and descending colons, and bilateral kidneys were measured for the lumbar spine. An "at risk" zone was defined as distance less than 10 mm anterior from the centre line of the intervertebral body.

RESULTS

Compared to supine preoperative CTs, bilateral kidneys at the L2/3 level as well as the bilateral colons at the L3/4 level had statistically significant ventral shift with prone positioning. The proportion of retroperitoneal organs within the at-risk zone ranged from 29.6 to 88.6% in the prone position.

CONCLUSIONS

The retroperitoneal organs shifted ventrally with prone positioning. However, the amount of shift was not large enough to avoid risk for organ injuries and substantial proportion of patients had organs within the cage insertion corridor. Careful preoperative planning is warranted when considering single-prone LLIF.

Efficacy and radiographic analysis of oblique lumbar interbody fusion in treating adult spinal deformity

Adult spinal deformity (ASD) is usually rigid and requires a combined anterior–posterior approach for deformity correction. Anterior lumbar interbody fusion (ALIF) allows direct access to the disc space and placement of a large interbody graft. A larger interbody graft facilitates correction of ASD. However, an anterior approach carries significant risks. Lateral lumbar interbody fusion (LLIF) through a minimally invasive approach has recently been used for ASD. The present study was performed to evaluate the effectiveness of oblique lumbar interbody fusion (OLIF) in the treatment of ASD. We performed a retrospective study utilizing the data of 74 patients with ASD. The inclusion criteria were lumbar coronal Cobb angle > 20°, pelvic incidence (PI)–lumbar lordosis (LL) mismatch > 10°, and minimum follow–up of 2 years. Patients were divided into two groups: ALIF combined with posterior spinal fixation (ALIF+PSF) (n = 38) and OLIF combined with posterior spinal fixation (OLIF+PSF) (n = 36). The perioperative spinal deformity radiographic parameters, complications, and health-related quality of life (HRQoL) outcomes were assessed and compared between the two groups. The preoperative sagittal vertical axis (SVA), LL, PI–LL mismatch, and lumbar Cobb angles were similar between the two groups. Patients in the OLIF+PSF group had a slightly higher mean number of interbody fusion levels than those in the ALIF+PSF group. At the final follow–up, all radiographic parameters and HRQoL scores were similar between the two groups. However, the rates of perioperative complications were higher in the ALIF+PSF than OLIF+PSF group. The ALIF+PSF and OLIF+PSF groups showed similar radiographic and HRQoL outcomes. These observations suggest that OLIF is a safe and reliable surgical treatment option for ASD.

Perioperative Complications in 255 Patients Who Underwent Lateral Anterior Lumbar Interbody Fusion (LaLIF) Surgery

PURPOSE

To investigate the perioperative complications of lateral anterior lumbar interbody fusion (LaLIF) surgery.

METHODS

The participants were patients who underwent LaLIF surgery for degenerative lumbar diseases between April 2016 and November 2020. The collected data were classified into intraoperative and early-stage postoperative (1 month) complications. Intraoperative complications were subcategorized into nerve root injury, sympathetic chain injury, segmental artery injury, iliolumbar vein injury, peritoneum laceration, temporary psoas injury, endplate damage, and vertebral body fractures. Postoperative complications were subcategorized into surgical site infection, cage migration, cage subsidence and psoas major hematoma.

RESULTS

In the 255 included patients, 39 complications (15.3%) were reported. One patient (0.4%) had residual neurological symptoms (numbness) at the last follow-up after conservative management. The most common complications were temporary psoas injury (3.9%), followed by sympathetic chain injury (2.7%) and endplate damage (2.0%). The most frequent postoperative complication was cage migration (1.6%), followed by cage subsidence (1.2%), and surgical site infection (0.8%).

CONCLUSION

The complication rates for LaLIF are generally low and comparable to those for conventional OLIF and XLIF that have been reported in other studies. Almost all complications were transient after LaLIF. Severe complications can be avoided by using sufficient muscle relaxant, instruments with the required characteristics and vertical trajectories in multiple steps.

Lateral-anterior lumbar interbody fusion (LaLIF) for lumbar degenerative disease: Technical notes, surgical system, and mid-term outcomes

Background

Many modified lateral lumbar interbody fusion techniques for lumbar degenerative diseases have been described by different authors. However, relatively high rates of vascular injury, peritoneal laceration, and even ureteral injury have been reported.

Purpose

The objectives of this study were firstly to present the detailed, standardized technical notes and describe the required standard characteristics of the designed surgical system of LaLIF and secondly to evaluate clinical outcomes and highlight the approach-related complications.

Methods

The mini-open LaLIF is described in a step-wise manner. The outcome measures were operative parameters, self-report measures, radiographic measures, and complications within 1 month of surgery. Operative parameters measured included operative time, intraoperative blood loss, and length of hospital stay. The self-report measures include Visual Analogue Scale (VAS), Oswestry disability index (ODI), and Short Form 36 Health Survey (SF-36) score. The radiographic measures including the intervertebral foraminal height (FH), intervertebral disc height (DH), and intervertebral foraminal area (FA) were assessed with plain radiography. The complication profiles were classified into intraoperative and postoperative (up to 1 month). Intraoperative complications were subcategorized into neurologic, vascular, ureteral, peritoneal, and vertebral injuries. Postoperative complications were subcategorized into infection, cage migration, and subsidence.

Results

A total of 126 patients who underwent LaLIF between April 2016 and December 2018 ​by a senior author were retrospectively reviewed. There were 54 males and 72 females (range 42–89 ​years old, average 65 ​± ​11 years old). The mean follow-up was 20 ​± ​11 ​months (range 6–38 ​months). The LaLIF was conducted at 188 levels in 126 patients, with 1 level in 75 cases, 2 levels in 42, 3 levels in 7, and 4 levels in 2 cases. There were 114 patients who underwent stand-alone LaLIF and 12 patients required secondary posterior fixation. The mean operative time, intraoperative blood loss, and length of hospital stay were recorded. The patient-reported outcome scores (VAS, ODI, and SF-36) and radiographic parameters (FH, DH, and FA) demonstrated a significant improvement after surgery and at the last follow-up. There were 25 (19.8%) complications in the 126 patients. The intraoperative complications accounted for 19 cases (15.1%) and postoperative accounted for 6 cases (4.8%). The most frequent complications were neurological injury (6.3%) and temporary psoas injury (6.3%).

Conclusions

The mini-open LaLIF, as a reproducible novel technique, can be performed safely at L2-L5. It is associated with reliable mid-term clinical outcomes and an acceptable complication profile when compared to traditional LLIF due to the advancements in the modified incision site, direct visualization, and usage of strictly vertical trajectory in multiple steps with the specially designed LaLIF system.

Translational potential statement

To make the lateral lumbar fusion process repeatable and also maintain a shallow learning curve, especially for surgeons in the early stages of learning, by using instruments with the required standard characteristics, the standardized surgical steps, modified incision site, vertical trajectory, and the direct visualization during the entire procedure.

Short-term comparison of preoperative and postoperative pain after indirect decompression surgery and direct decompression surgery in patients with degenerative spondylolisthesis

The purpose of this study was to compare the short-term clinical outcomes between extreme lateral interbody fusion (XLIF) and minimally invasive surgery (MIS)–transforaminal interbody fusion (TLIF) in patients with degenerative spondylolisthesis with stenosis. One hundred-six patients were enrolled; 44 were treated with MIS–TLIF (direct decompression group; DP), and 62 were treated with XLIF (indirect decompression group; IDP). Perioperative indexes included operation time and intraoperative bleeding. Perioperative indexes preoperative and postoperative numeric rating scale (NRS) scores for low back pain (NRS-BP), leg pain (NRS-LP), and leg numbness (NRS-LN), and the preoperative score on the Japanese version of the painDETECT questionnaire (PDQ-J) were also assessed. The average follow-up period for the collection of NRS scores was 12.6 months. The operation time was significantly shorter in the IDP than in the DP group (109.9 ± 35.4 vs. 153.3 ± 50.9 min; p < 0.001). Intraoperative blood loss was also significantly less in the IDP group than in the DP group (85.4 ± 125.4 vs. 258.3 ± 220.4 mL; p < 0.001). The PDQ-J score and preoperative NRS scores (NRS-BP, NRS-LP, and NRS-LN) did not differ significantly between groups. Less improvement in the NRS-BP (ΔNRS-BP) was observed in the DP group than in the IDP group (p < 0.05). Although pain improved after surgery in both groups, IDP surgery was advantageous in minimizing bleeding and preserving posterior support elements such as the facet joints, lamina, and paraspinal muscles. These findings suggest that this may have contributed to the higher rate of improvement in low back pain compared with DP surgery.

Correlation study of radiographic characteristics and operative difficulty in lateral-anterior lumbar interbody fusion (LaLIF) at the L4-5 level: a novel classification for case selection

PURPOSE

To analyze correlations between the realistic surgical difficulty of LaLIF and anatomic characteristics in radiographic images, in order to develop a simple classification to provide guiding information for case selection and evaluate the potential risks of the technique.

METHODS

Ninety-six consecutive cases who underwent LaLIF surgeries at the L4-5 level with MR T2-weighted images were analyzed. A novel classification based on the anatomic relationships among the disk, great vessels, and psoas muscle was used for grouping. Clinical outcomes and realistic surgical difficulty parameters were recorded, and comparisons were made among different types of classifications.

RESULTS

Of the 96 analyzed cases, the time of surgical exposure was significantly longer for type C than for type B, and both of these were longer than that of type A. The VAS and ODI were significantly improved at a 1-year follow-up. There was no statistically significant difference among the three types. Type C had the highest incidence of complications, while Type A had the lowest. Analyses of another 304 MRI cases obtained in outpatient clinics showed that the distribution of the three types among these cases was consistent with that of the surgical cohort.

CONCLUSION

Our novel and simple classification provides useful information for case selection. Type A provided the best indication and is most appropriate for a beginner in this technique. Type C includes the most challenging situations, which may have a high incidence of complications and require sophisticated surgical skills to achieve satisfactory outcomes and avoid approach-related complications.

The Anatomic Characteristics of the Retroperitoneal Oblique Corridor to the L1-S1 Intervertebral Disc Spaces

STUDY DESIGN

This is a cross-sectional study.

OBJECTIVE

To investigate the oblique corridor to the L1-S1 intervertebral disc space between the psoas muscle and the great vessels in cadaveric specimens bilaterally and the location of genitofemoral nerve and the diaphragmatic crura relative to the oblique corridor.

SUMMARY OF BACKGROUND DATA

Although use of oblique lumbar interbody fusion is rapidly expanding, the morphometric data related to the procedure are limited.

METHODS

Twelve fresh-frozen full-torso cadaveric specimens were dissected to examine the oblique corridor to access the L1-S1 space in a static state and with mild retraction of the psoas. The level at which the genitofemoral nerve pierces from the psoas major and the diaphragmatic crura originate from the lumbar vertebral body was also investigated.

RESULTS

The mean width of oblique corridor in the static state and with mild psoas retraction, respectively, were as follows: on the right side: (L1-2) 13.33 and 16.75 mm; (L2-3) 15.42 and 21.42 mm; (L3-4) 16.58 and 22.67 mm; (L4-5) 12.75 and 21.17 mm; (L5-S1) 5.92 and 12.00 mm; on the left side: (L1-2) 16.75 and 19.67 mm; (L2-3) 18.50 and 25.33 mm; (L3-4) 20.58 and 28.00 mm; (L4-5) 18.17 and 26.08 mm; and (L5-S1) 5.83 and 12.00 mm. The level at which the genitofemoral nerve pierces from the psoas major was between L2 and L4. The diaphragmatic crura originates from L1 to L3.

CONCLUSION

The oblique corridor allows access to the L1-L5 discs from both sides, but it is larger on the left side. The corridor between the iliac vessels and the psoas for L5-S1 is difficult to be applied clinically. Mild psoas retraction can moderately enlarge the oblique corridor. The genitofemoral nerve and diaphragmatic crura may be encountered in this approach and should be carefully observed.

LEVEL OF EVIDENCE

5.

Lateral Lumbar Interbody Fusion Revisited: Complication Avoidance and Outcomes with the Mini-Open Approach

OBJECTIVE

To discuss lessons learned from an initial lateral lumbar interbody fusion (LLIF) experience with a focus on evolving surgical technique, complication avoidance, and new motor and sensory outcomes after implementation of a modified surgical approach.

METHODS

A retrospective analysis of a prospectively collected series of all patients undergoing LLIF by the senior author (A.D.L.) from January 2010 to January 2018 after implementation of a modified surgical mini-open technique, compared with previously reported institutional results with the originally recommended percutaneous technique. LLIF-specific complications examined included groin/thigh sensory dysfunction, flank bulge/pseudohernia, psoas-pattern weakness, and femoral nerve injury.

RESULTS

The incidence (19%, n = 98 patients) of groin/thigh sensory dysfunction in our cohort was significantly lower than that of the historical control (60%, n = 59) (P < 0.0001). The incidence of abdominal flank bulge/pseudohernia (2.0%, n = 98 patients) in our cohort was improved but not significantly lower than that of the historical control (4.2%, n = 118) (P = 0.36). The incidence of psoas-pattern weakness (3.1%, n = 98) in our cohort was significantly lower than that of the historical control (23.7%, n = 59) (P = 0.0001). The incidence of femoral nerve injury (0%, n = 98 patients) in our cohort was improved but was not significantly lower than that of the historical control (1.7%, n = 118) (P = 0.20).

CONCLUSIONS

The adoption of an exclusive mini-open muscle-splitting approach with first-look inspection of the lumbosacral plexus nerve elements may improve motor and sensory outcomes in general and the incidence of postoperative groin/thigh sensory dysfunction and psoas-pattern weakness in particular.

Lateral Lumbar Interbody Fusion-Outcomes and Complications

PURPOSE OF REVIEW

Lateral lumbar interbody fusion (LLIF) is a relatively new, minimally invasive technique for interbody fusion. The goal of this review is to provide a general overview of LLIF with a special focus on outcomes and complications.

RECENT FINDINGS

Since the first description of the technique in 2006, the indications for LLIF have expanded and the rate of LLIF procedures performed in the USA has increased. LLIF has several theoretical advantages compared to other approaches including the preservation of the anterior and posterior annular/ligamentous structures, insertion of wide cages resting on the dense apophyseal ring bilaterally, and augmentation of disc height with indirect decompression of neural elements. Favorable long-term outcomes and a reduced risk of visceral/vascular injuries, incidental dural tears, and perioperative infections have been reported. However, approach-related complications such as motor and sensory deficits remain a concern. In well-indicated patients, LLIF can be a safe procedure used for a variety of indications.

Morphometric anatomy of the lumbar sympathetic trunk with respect to the anterolateral approach to lumbar interbody fusion: a cadaver study

BACKGROUND

An approach to lateral lumbar interbody fusion (LLIF) utilizing an oblique corridor anterior to the psoas muscle was first described by Mayer in 1997 and subsequently by other authors. The only consistent structure of note in this corridor is the lumbar sympathetic trunk (LST), which at times must be mobilized in order to perform a discectomy and interbody fusion, thereby placing the LST at risk. This study was designed to describe the morphometric anatomy of the LST in relation to surgically relevant landmarks for the anterolateral approach to the lumbar spine at L3/L4 to L5/S1.

METHODS

Twenty-four embalmed cadavers (13 males, 11 females, age range, 50-89) were dissected to expose the LST. Bilateral measurements were recorded using a calliper under direct visualization, using the midsagittal plane of the lumbar spine as the reference landmark. The points were then marked with radio-opaque needles, and 14 cadavers were scanned with CT to validate the measurements.

RESULTS

Of 48 LSTs, there was minimal difference in the direction of its course between sides; 14/24 specimens had concordant directions. The majority (n=28) had a medial to lateral cephalocaudal course. If osteophytes were present at the L4/L5 level, the majority of LSTs (n=7, of 8) were displaced lateral to the osteophyte. At the L5/S1 level, half of the cases with osteophytes (n=3, of 6) stretched the LST over the top of the osteophyte. The LST was adherent to the L4/L5 disc space bilaterally in 93% of cases.

CONCLUSIONS

With the development of lumbar fusion techniques which utilize an oblique corridor and the retraction of psoas muscle, LST has become an important neural structure to define, protect and mobilize. In our morphometric analysis of 24 specimens, the position has been identified and quantified, and this paper notes variations, particularly distortions caused by degenerative processes. In this study, the LST ran in a medial to lateral direction from L3 to S1, and osteophytes typically displace and adhere to the LST.

The Oblique Anterolateral Approach to the Lumbar Spine Provides Access to the Lumbar Spine With Few Early Complications

BACKGROUND

During the last 20 years several less-invasive anterior approaches to the lumbar spine have become standard, including the extreme lateral transpsoas approach. Although it is associated with a lower risk of vascular injury compared with anterior midline approaches, neuromonitoring is considered mandatory to avoid neurologic complications. Interestingly, despite neuromonitoring, the reported risk of neurologic deficits with the extreme lateral transpsoas approach is greater than observed with other anterior approaches. An alternative lateral, oblique, psoas-sparing approach, recently named the oblique lumbar interbody fusion, uses the anatomic pathway between the abdominal vessels anteriorly and the lumbar plexus laterally to decrease the risk of neurologic and vascular injury; however, as yet, little on this new approach has been reported.

QUESTIONS/PURPOSES

We asked: what proportion of patients experienced (1) perioperative complications (overall complications), (2) vascular complications, and (3) neurologic complications after less-invasive anterior lumbar interbody fusion through the oblique lumbar interbody approach at one high-volume center?

METHODS

We performed a chart review of intra- and perioperative complications of all patients who had undergone minimally invasive anterior lumbar interbody fusion through a lateral psoas-sparing approach from L1 to L5 during a 12-year period (1998-2010). During the study period, the oblique, psoas-sparing approach was the preferred approach of the participating surgeons in this study, and it was performed in 812 patients, all of whom are studied here, and all of whom have complete data for assessment of the short-term (inpatient-only) complications that we studied. In general, we performed this approach whenever possible, although it generally was avoided when a patient previously had undergone an open retro- or transperitoneal abdominal procedure, or previous implantation of hernia mesh in the abdomen. During the study period, posterior fusion techniques were used in an additional 573 patients instead of the oblique lumbar interbody fusion when we needed to decompress the spinal canal beyond what is possible through the anterior approach. In case of spinal stenosis calling for fusion in combination with a high disc space, severe endplate irregularity, or severe biomechanical instability, we combined posterior decompression with oblique lumbar interbody fusion in 367 patients. Complications were evaluated by an independent observer who was not involved in the decision-making process, the operative procedure, nor the postoperative care by reviewing the inpatient records and operative notes.

RESULTS

A total of 3.7% (30/812) of patients who underwent the oblique lumbar interbody fusion experienced a complication intraoperatively or during the hospital stay. During the early postoperative period there were two superficial (0.24%) and three deep (0.37%) wound infections and five superficial (0.62%) and six deep (0.86%) hematomas. There were no abdominal injuries or urologic injuries. The percentage of vascular complications was 0.37% (n = 3). The percentage of neurologic complications was 0.37% (n = 3).

CONCLUSIONS

The risk of vascular complications after oblique lumbar interbody fusion seems to be lower compared with reported risk for anterior midline approaches, and the risk of neurologic complications after oblique lumbar interbody fusion seems to be lower than what has been reported with the extreme lateral transpsoas approach; however, we caution readers that head-to-head studies will need to be performed to confirm our very preliminary comparisons and results with the oblique psoas-sparing approach. Similarly, future studies will need to evaluate this approach in terms of later-presenting complications, such as infection and pseudarthrosis formation, which could not be assessed using this inpatient-only approach. Nevertheless, with the results of this study the oblique psoas-sparing approach can be described as a less-invasive alternative for anterior lumbar fusion surgery from L1 to L5 with a low risk of vascular and neurologic damage and without costly intraoperative neuromonitoring tools.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

A new extensile anterolateral retroperitoneal approach for lumbar interbody fusion from L1 to S1: a prospective series with clinical outcomes

BACKGROUND CONTEXT

A variety of surgical approaches have been used for cage insertion in lumbar interbody fusion surgery. The direct anterior approach requires mobilization of the great vessels to access the intervertebral disc spaces cranial to L5/S1. With the lateral retroperitoneal transpsoas approach, it is difficult to access the L4/L5 intervertebral disc space due to the lumbar plexus and iliac crest, and L5/S1 is inaccessible. We describe a new anterolateral retroperitoneal approach, which is safe and reproducible to access the disc spaces from L1 to S1 inclusive, obviating the need for a separate direct anterior approach to access L5/S1.

PURPOSE

This paper had the following objectives: first, to report a reproducible novel single-incision, muscle-splitting, anterolateral pre-psoas surgical approach to the lumbar spine from L1 to S1; second, to highlight the technical challenges of this approach and highlight approach-related complications; and third, to evaluate clinical outcomes using this surgical technique in a prospective series of L1 to S1 anterior lumbar interbody fusions (ALIFs) performed as part of a 360-degree fusion for adult spinal deformity correction.

STUDY DESIGN

This report used a prospective cohort study.

PATIENT SAMPLE

A prospective series of patients (n=64) having ALIF using porous tantalum cages as part of a two-stage complex spinal reconstruction from L1 to S1 were studied.

OUTCOME MEASURES

Data collected included blood loss, operative time, incision size, technical challenges, perioperative complications, and secondary procedures. Clinical outcome measures used included visual analogue scale (VAS) Back Pain, VAS Leg Pain, EuroQoL-5 Dimensions (EQ-5D), EQ-5D VAS, Oswestry Disability Index (ODI), and Scoliosis Research Society-22 (SRS-22).

METHODS

Pre- and postoperative radiographic parameters and clinical outcome measures were assessed. Mean follow-up time was 1.8 years.

RESULTS

Mean blood loss was 68±9.6 mL. The mean VAS Back Pain score improved from 7.5±1.25 preoperatively to 2.5±1.7 at 3 months (p=.02), 1.2±0.5 at 6 months (p=.01), and 1.4±0.6 at 1 year (p=.02). The mean ODI improved from 64.3±31.8 preoperatively to 16.6±14.7 at 3 months (p>.05), 10.7±6.0 at 6 months (p=.02), and 6.7±6.1 at 1 year (p=.01). There were no permanent neurologic, vascular, or visceral injuries. One revision anterior procedure was required on a patient with rheumatoid arthritis and advanced systemic disease that sustained a sacral fracture and required revision ALIF at L5/S1.

CONCLUSIONS

The technique described is a safe, new, muscle-splitting, psoas-preserving, one-incision approach to provide access from L1 to S1 for multilevel anterior or oblique lumbar interbody fusion surgery.

Single-level lumbar pyogenic spondylodiscitis treated with mini-open anterior debridement and fusion in combination with posterior percutaneous fixation via a modified anterior lumbar interbody fusion approach

OBJECT

This study evaluated the efficacy and safety of mini-open anterior debridement and lumbar interbody fusion in combination with posterior percutaneous fixation for single-level lumbar pyogenic spondylodiscitis.

METHODS

This is a retrospective study. Twenty-two patients with single-level lumbar pyogenic spondylodiscitis underwent mini-open anterior debridement and lumbar interbody fusion in combination with posterior percutaneous fixation via a modified anterior lumbar interbody fusion (ALIF) approach. Patients underwent follow-up for 24 to 38 months. Clinical data, etiological examinations, operative time, intraoperative blood loss, American Spinal Injury Association (ASIA) grade, Japanese Orthopaedic Association (JOA) lumbar function score, visual analog scale (VAS) score, Oswestry Disability Index (ODI), postoperative complications, and the bony fusion rate were recorded.

RESULTS

The mean operative time was 181.1 ± 22.6 minutes (range 155-240 minutes). The mean intraoperative blood loss was 173.2 ± 70.1 ml (range 100-400 ml). Infection was found in lumbar vertebrae L2-3, L3-4, and L4-5 in 2, 6, and 14 patients, respectively. Bacterial cultures were positive in 15 patients, including 4 with Staphylococcus aureus, 6 with Staphylococcus epidermidis, 4 with Streptococcus, and 1 with Escherichia coli. Postoperative complications included urinary retention, constipation, and numbness in the thigh in 5, 3, and 2 patients, respectively. Compared with before surgery, the VAS scores and ODI were significantly lower at the final follow-up, the JOA scores were significantly higher, and the ASIA grades had improved. All patients achieved good intervertebral bony fusion.

CONCLUSIONS

Mini-open anterior debridement and lumbar interbody fusion in combination with posterior percutaneous fixation via a modified ALIF approach results in little surgical trauma and intraoperative blood loss, acceptable postoperative complications, and is effective and safe for the treatment of single-level lumbar pyogenic spondylodiscitis. This approach could be an alternative to the conventional open surgery.

In vitro evaluation of a lateral expandable cage and its comparison with a static device for lumbar interbody fusion: a biomechanical investigation

OBJECT

Through in vitro biomechanical testing, the authors compared the performance of a vertically expandable lateral lumbar interbody cage (EC) under two different torque-controlled expansions (1.5 and 3.0 Nm) and with respect to an equivalent lateral lumbar static cage (SC) with and without pedicle screw fixation.

METHODS

Eleven cadaveric human L2-3 segments were evaluated under the following conditions: 1) intact; 2) discectomy; 3) EC under 1.50 Nm of torque expansion (EC-1.5Nm); 4) EC under 3.00 Nm of torque expansion (EC-3.0Nm); 5) SC; and 6) SC with a bilateral pedicle screw system (SC+BPSS). Load-displacement behavior was evaluated for each condition using a combination of 100 N of axial preload and 7.5 Nm of torque in flexion and extension (FE), lateral bending (LB), and axial rotation (AR). Range of motion (ROM), neutral zone stiffness (NZS), and elastic zone stiffness (EZS) were statistically compared among conditions using post hoc Wilcoxon signed-rank comparisons after Friedman tests, with a significance level of 0.05. Additionally, any cage height difference between interbody devices was evaluated. When radiographic subsidence was observed, the specimen's data were not considered for the analysis.

RESULTS

The final cage height in the EC-1.5Nm condition (12.1 ± 0.9 mm) was smaller (p < 0.001) than that in the EC-3.0Nm (13.9 ± 1.1 mm) and SC (13.4 ± 0.8 mm) conditions. All instrumentation reduced (p < 0.01) ROM with respect to the injury and increased (p ≤ 0.01) NZS in flexion, extension, and LB as well as EZS in flexion, LB, and AR. When comparing the torque expansions, the EC-3.0Nm condition had smaller (p < 0.01) FE and AR ROM and greater (p ≤ 0.04) flexion NZS, extension EZS, and AR EZS. The SC condition performed equivalently (p ≥ 0.10) to both EC conditions in terms of ROM, NZS, and EZS, except for EZS in AR, in which a marginal (p = 0.05) difference was observed with respect to the EC-3.0Nm condition. The SC+BPSS was the most rigid construct in terms of ROM and stiffness, except for 1) LB ROM, in which it was comparable (p = 0.08) with that of the EC-1.5Nm condition; 2) AR NZS, in which it was comparable (p > 0.66, Friedman test) with that of all other constructs; and 3) AR EZS, in which it was comparable with that of the EC-1.5Nm (p = 0.56) and SC (p = 0.08) conditions.

CONCLUSIONS

A 3.0-Nm torque expansion of a lateral interbody cage provides greater immediate stability in FE and AR than a 1.5-Nm torque expansion. Moreover, the expandable device provides stability comparable with that of an equivalent (in size, shape, and bone-interface material) SC. Specifically, the SC+BPSS construct was the most stable in FE motion. Even though an EC may seem a better option given the minimal tissue disruption during its implantation, there may be a greater chance of endplate collapse by over-distracting the disc space because of the minimal haptic feedback from the expansion.