Kevin A. Seex

Clinical outcome and fusion rates after the first 30 extreme lateral interbody fusions

Introduction. The lateral transpsoas approach for lumbar interbody fusion (XLIF) is gaining popularity. Studies examining a surgeons early experience are rare. We aim to report treatment, complication, clinical, and radiographic outcomes in an early series of patients. Methods. Prospective data from the first thirty patients treated with XLIF by a single surgeon was reviewed. Outcome measures included pain, disability, and quality of life assessment. Radiographic assessment of fusion was performed by computed tomography. Results. Average follow-up was 11.5 months, operative time was 60 minutes per level and blood loss was 50 mL. Complications were observed: clinical subsidence, cage breakage upon insertion, new postoperative motor deficit and bowel injury. Approach side-effects were radiographic subsidence and anterior thigh sensory changes. Two patients required reoperation; microforaminotomy and pedicle screw fixation respectively. VAS back and leg pain decreased 63% and 56%, respectively. ODI improved 41.2% with 51.3% and 8.1% improvements in PCS and MCS. Complete fusion (last follow-up) was observed in 85%. Conclusion. The XLIF approach provides superior treatment, clinical outcomes and fusion rates compared to conventional surgical approaches with lowered complication rates. Mentor supervision for early cases and strict adherence to the surgical technique including neuromonitoring is essential.

Maintenance of segmental lordosis and disk height in stand-alone and instrumented extreme lateral interbody fusion (XLIF).

Study Design: A prospective single-surgeon nonrandomized clinical study. Objective: To evaluate the radiographic and clinical outcomes, by fixation type, in extreme lateral interbody fusion (XLIF) patients and provide an algorithm for determining patients suitable for stand-alone XLIF. Summary of Background Data: XLIF may be supplemented with pedicle screw fixation, however, since stabilizing structures remain intact, it is suggested that stand-alone XLIF can be used for certain indications. This eliminates the associated morbidity, though subsidence rates may be elevated, potentially minimizing the clinical benefits. Materials and Methods: A fixation algorithm was developed after evaluation of patient outcomes from the surgeon’s first 30 cases. This algorithm was used prospectively for 40 subsequent patients to determine the requirement for supplemental fixation. Preoperative, postoperative, and 12-month follow-up computed tomography scans were measured for segmental and global lumbar lordosis and posterior disk height. Clinical outcome measures included back and leg pain (visual analogue scale), Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS). Results: Preoperatively to 12-month follow-up there were increases in segmental lordosis (7.9–9.4 degrees, P=0.0497), lumbar lordosis (48.8–55.2 degrees, P=0.0328), and disk height (3.7–5.5 mm, P=0.0018); there were also improvements in back (58.6%) and leg pain (60.0%), ODI (44.4%), PCS (56.7%), and MCS (16.1%) for stand-alone XLIF. For instrumented XLIF, segmental lordosis (7.6–10.5 degrees, P=0.0120) and disk height (3.5–5.6 mm, P<0.001) increased, while lumbar lordosis decreased (51.1–45.8 degrees, P=0.2560). Back (49.8%) and leg pain (30.8%), ODI (32.3%), PCS (37.4%), and MCS (2.0%) were all improved. Subsidence occurred in 3 (7.5%) stand-alone patients. Conclusions: The XLIF treatment fixation algorithm provided a clinical pathway to select suitable patients for stand-alone XLIF. These patients achieved positive clinical outcomes, satisfactory fusion rates, with sustained correction of lordosis and restoration of disk height.

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography

OBJECT Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF. METHODS A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores. RESULTS Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049). CONCLUSIONS The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

Intraosseous hibernoma: characterization of five cases and literature review

ObjectiveTo describe the imaging and histopathological findings and provide an overview of a recently described and rare cause of bone sclerosis.Materials and methodsFive cases of intra-osseous hibernoma of bone that presented over the last year. The imaging and histopathology is reviewed.ResultsAll cases were identified in asymptomatic middle-aged to elderly adults as incidental findings with bone sclerosis in the axial skeleton. MRI showed lesions that were T1 hypointense to subcutaneous fat and hyperintense to skeletal muscle and one showed contrast enhancement. Glucose avidity was demonstrated on FDGPET in both cases tested and isotope bone scan performed in three cases showed strong positivity in two, but uptake was inconspicuous in one case.ConclusionsIntra-osseous hibernoma is a rare cause of sclerotic bone lesions, predominating in the axial skeleton of middle-aged and elderly adults. They have a non-aggressive appearance on CT and on MRI are T1 hypointense to subcutaneous fat and hyperintense to skeletal muscle. They are usually T2 hyperintense and may show peripheral contrast enhancement. They may show increased glucose avidity on FDGPET and may or may not be positive on isotope bone scans. We suspect that with ever-increasing use of a variety of imaging techniques, particularly in a setting of staging for malignant disease, more such cases will come to light. This diagnosis should be added to the differential diagnosis of sclerotic bone lesions.

Anterior to psoas fusion of the lumbar spine

Lateral interbody cages have proven useful in lumbar fusion surgery. Spanning both lateral cortical rims while sparing the anterior longitudinal ligament, they restore disc height, improve coronal balance and add stability. The standard approach to their insertion is 90 degrees lateral transpsoas which is bloodless compared to other techniques of interbody cage insertion but requires neuro-monitoring and at L4/5 can be difficult because of iliac crest obstruction or an anterior plexus position. The oblique muscle-splitting approach with the patient in a lateral position, remains retroperitoneal, and on the left side enters the disc space through a window between psoas and the common iliac vein. Reports of this approach are few and none previously have described how to use the large lateral-type cages so effective at restoring spinal alignment. In this video we demonstrate our technique of anterior to psoas fusion of the lumbar spine with a retroperitoneal approach and gentle retraction of the psoas muscle. The video can be found here: http://youtu.be/OS2vNcX9JMA.

Early postoperative dislocation of the anterior Maverick lumbar disc prosthesis : report of 2 cases

The authors report on 2 cases of anterior dislocation of the Maverick lumbar disc prosthesis, both occurring in the early postoperative period. These cases developed after experience with more than 50 uneventful cases and were therefore thought to be unrelated to the surgeons learning curve. No similar complications have been previously reported. The anterior Maverick device has a ball-and-socket design made of cobalt-chromium-molybdenum metal plates covered with hydroxyapatite. The superior and inferior endplates have keels to resist translation forces. The patient in Case 1 was a 52-year-old man with severe L4-5 discogenic pain; and in Case 2, a 42-year-old woman with disabling L4-5 and L5-S1 discogenic back pain. Both patients were without medical comorbidities and were nonsmokers with no risk factors for osteoporosis. Both had undergone uneventful retroperitoneal approaches performed by a vascular access surgeon. Computed tomography studies on postoperative Day 2 confirmed excellent prosthesis placement. Initial recoveries were uneventful. Two weeks postoperatively, after stretching (extension or hyperextension) in bed at home, each patient suffered the sudden onset of severe abdominal pain with anterior dislocation of the Maverick prosthesis. The patients were returned to the operating room and underwent surgery performed by the same spinal and vascular surgeons. Removal of the Maverick prosthesis and anterior interbody fusion with a separate cage and plate were performed. Both patients had recovered well with good clinical and radiological recovery at the 6- and 12-month follow-ups. Possible causes of the anterior dislocation of the Maverick prosthesis include the following: 1) surgeon error: In both cases the keel cuts were neat, and early postoperative CT confirmed good placement of the prosthesis; 2) equipment problem: The keel cuts may have been too large because the cutters were worn, which led to an inadequate press fit of the implants; 3) prosthesis fault: Both plates of the dislocated implants looked normal and manufacturer analysis reported no fault; 4) patient factors: Both dislocations happened early in the postoperative period, after hyperextension of the spine while the patient was supine in bed. Bracing would not have reduced hyperextension. Dislocation of a lumbar spinal implant represents a life-threatening complication and should therefore be considered and recognized early. Radiographic and CT studies of both the lumbar spine (for prosthesis) and the abdomen (for hematoma) should be performed, as should CT angiography (for vessel damage or occlusion). Any anterior lumbar revision surgery is hazardous, and it is strongly advisable to have a vascular surgeon scrubbed. In cases of dislocation or extrusion of a lumbar interbody prosthesis, the salvage revision strategy is fusing the segment via the same anterior approach. Surgeons should be aware of the risk of anterior dislocation of the Maverick prosthesis. Keel cutters should be regularly checked for sharpness, as they may be implicated in the loosening of implants. Patients and their physical therapists should also avoid lumbar hyperextension in the early postoperative period.

Anterior to psoas (ATP) fusion of the lumbar spine: evolution of a technique facilitated by changes in equipment

BACKGROUND Lateral interbody cages have been proven useful in spinal fusions. Spanning both lateral cortical rims while sparing the Anterior Longitudinal Ligament, the lateral interbody cages restore and maintain disc height while adding stability prior to supplemental fixation. The standard approach for their insertion is by a 90-degree lateral transpsoas method. This is relatively bloodless compared to other techniques although has its limitations, requiring neuro-monitoring and being, at times, very difficult at L4/5 due to iliac crest obstruction or an anterior plexus position. An oblique approach, with the patient in lateral decubitus, passes anterior to the iliac crest, retroperitoneal, and being anterior to psoas, eliminates the need for neuro-monitoring. METHODS Twenty-one consecutive patients underwent surgery for a total of 32 levels instrumented with the ATP technique. Mean age at the time of surgery was 62.4±7.4 years. There was a 6 months minimum clinical follow up, with imaging to assess fusion, at 6 and 12 months. Indications included symptomatic degenerative lumbar spondylosis +/- spondylolisthesis, leg and back pain. All patients were assessed with the Oswestry Disability Index (ODI), Visual Analog Scale 100 mm for back pain (VASb) and for leg pain (VASl) preoperatively, at 3, 6 and 12 months. Last follow-up was at 12 months for 9 patients and the rest had 6 months follow up. RESULTS Statistical analysis showed significance for the results in ODI, VASb and VASl with improvement in all components except for one patient with worsening VASl. Eight patients had complications related to surgery which were still present at last follow-up including moderate weakness of hip flexion and EHL weakness. Lateral cutaneous nerve (LCN) palsy on the side of the approach was also seen as well as sympathectomy effect related to the mobilization of the sympathetic trunk. One patient, who also suffered from multiple sclerosis, experienced psoas abscess 3 months post op that required drainage. CONCLUSIONS The left sided anterior to psoas approach offers the most natural corridor to the disc space. The novel instruments and method described here allows insertion of large lateral cages between L2 to L5, without the problems associated with the transpsoas approach, particularly at L4/5.

Choice of Approach Does Not Affect Clinical and Radiologic Outcomes: A Comparative Cohort of Patients Having Anterior Lumbar Interbody Fusion and Patients Having Lateral Lumbar Interbody Fusion at 24 Months.

Study Design Retrospective analysis of prospectively collected registry data. Objective This study aimed to compare the clinical and radiologic outcomes between comparative cohorts of patients having anterior lumbar interbody fusion (ALIF) and patients having lateral lumbar interbody fusion (LLIF). Methods Ninety consecutive patients were treated by a single surgeon with either ALIF (n = 50) or LLIF (n = 40). Inclusion criteria were patients age 45 to 70 years with degenerative disk disease or grade 1 to 2 spondylolisthesis and single-level pathology from L1 to S1. Patient-reported outcome measures included pain (visual analog scale), disability (Oswestry Disability Index [ODI]), and quality of life (Short Form 36 physical component score [PCS] and mental component scores [MCS]). Assessment of fusion and measurement of lordosis and posterior disk height were performed on computed tomography scans. Results At 24 months, patients having ALIF had significant improvements in back (64%) and leg (65%) pain and ODI (60%), PCS (44%), and MCS (26%; p < 0.05) scores. Patients having LLIF had significant improvements in back (56%) and leg (57%) pain and ODI (52%), PCS (48%), and MCS (12%; p < 0.05) scores. Fourteen complications occurred in the ALIF group, and in the LLIF group, there were 17 complications (p > 0.05). The fusion rate was 100% for ALIF and 95% for LLIF (p = 0.1948). ALIF added ∼6 degrees of lordosis and 3 mm of height, primarily measured at L5–S1, and LLIF added ∼3 degrees of lordosis and 2 mm of height between L1 to L5. Mean follow-up was 34.1 months. Conclusions In comparative cohorts of patients having ALIF and patients having LLIF at 24 months postoperatively, there were no significant differences in clinical outcomes, complication rates, or fusion rates.

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.

Anterior to Psoas (ATP) Fusion of the Lumbar Spine

When fusing a lumbar spinal segment, certain facts are well established: the disc should be removed, the end plates prepared carefully, and then graft material placed against the end plates, contained or supported by a lordotic cage. The cage will help correct any deformity, resist subsidence, and improve stability. In an “ideal cage” competition, the large lateral cages are the obvious winners when compared to PLIF, TLIF, or ALIF cages. Spanning both lateral cortical rims while sparing the anterior longitudinal ligament, they provide the best support, most graft volume, and most stability for the anterior column even without supplemental fixation. The standard approach for their insertion and placement is also the most logical going through both lateral annuli without disrupting normal stabilizing structures. None of the above is in dispute. The question raised in this chapter is whether the best access to the lateral annulus is really transpsoas (i.e., through the psoas muscle).