Decompression of Lumbar Central Spinal Canal Stenosis Following Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: This was a retrospective clinical series. OBJECTIVE: The objective of this study was to evaluate radiologic changes in central spinal canal dimensions following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with placement of a static or an expandable interbody device. SUMMARY OF BACKGROUND DATA: MIS-TLIF is used to treat lumbar degenerative diseases and low-grade spondylolisthesis. MIS-TLIF enables direct and indirect decompression of lumbar spinal stenosis, with patients experiencing relief from radiculopathy and neurogenic claudication. However, the effects of MIS-TLIF on the central spinal canal are not well-characterized. MATERIALS AND METHODS: We identified patients who underwent MIS-TLIF for degenerative lumbar spondylolisthesis and concurrent moderate to severe spinal stenosis. We selected patients who had both preoperative and postoperative magnetic resonance imaging (MRI) and upright lateral radiographs of the lumbar spine. Measurements on axial T2-weighted MRI scans include anteroposterior and transverse dimensions of the dural sac and osseous spinal canal. Measurements on radiographs include disk height, neural foraminal height, segmental lordosis, and spondylolisthesis. We made pairwise comparisons between each of the central canal dimensions and lumbar sagittal segmental radiologic outcome measures relative to their corresponding preoperative values. Correlation coefficients were used to quantify the association between changes in lumbar sagittal segmental parameters relative to changes in radiologic outcomes of central canal dimensions. Statistical analysis was performed for "all patients" and further stratified by interbody device subgroups (static and expandable). RESULTS: Fifty-one patients (age 60.4 y, 68.6% female) who underwent MIS-TLIF at 55 levels (65.5% at L4-L5) were included in the analysis. Expandable interbody devices were used in 45/55 (81.8%) levels. Mean duration from surgery to postoperative MRI scan was 16.5 months (SD 11.9). MIS-TLIF was associated with significant improvements in dural sac dimensions (anteroposterior +0.31 cm, transverse +0.38 cm) and osseous spinal canal dimensions (anteroposterior +0.16 cm, transverse +0.32 cm). Sagittal lumbar segmental parameters of disk height (+0.56 cm), neural foraminal height (+0.35 cm), segmental lordosis (+4.26 degrees), and spondylolisthesis (-7.5%) were also improved following MIS-TLIF. We did not find meaningful associations between the changes in central canal dimensions relative to the corresponding changes in any of the sagittal lumbar segmental parameters. Stratified analysis by interbody device type (static and expandable) revealed similar within-group changes as in the overall cohort and minimal between-group differences. CONCLUSIONS: MIS-TLIF is associated with radiologic decompression of neural foraminal and central spinal canal stenosis. The mechanism for neural foraminal and central canal decompression is likely driven by a combination of direct and indirect corrective techniques.

The influence of sagittal spinopelvic alignment on patient discharge disposition following minimally invasive lumbar interbody fusion.

BACKGROUND: The aim of this study was to investigate the changes to spinopelvic sagittal alignment following minimally invasive (MIS) lumbar interbody fusion, and the influence of such changes on postoperative discharge disposition. METHODS: The Michigan Spine Surgery Improvement Collaborative was queried for all patients who underwent transforaminal lumbar interbody fusion (TLIF)or lateral lumbar interbody fusion (LLIF) procedures for degenerative spine disease. Several spinopelvic sagittal alignment parameters were measured, including sagittal vertical axis (SVA), lumbar lordosis, pelvic tilt, pelvic incidence, and pelvic incidence-lumbar lordosis mismatch. Primary outcome measure-discharge to a rehabilitation facility-was expressed as adjusted odds ratio (ORadj) following a multivariable logistical regression. RESULTS: Of the 83 patients in the study population, 11 (13.2%) were discharged to a rehabilitation facility. Preoperative SVA was equivalent. Postoperative SVA increased to 8.0 cm in the discharge-to-rehabilitation division versus a decrease to 3.6 cm in the discharge-to-home division (P<0.001). The odds of discharge to a rehabilitation facility increased by 25% for every 1-cm increase in postoperative sagittal balance (ORadj =1.27, P=0.014). The strongest predictor of discharge to rehabilitation was increasing decade of life (ORadj =3.13, P=0.201). CONCLUSIONS: Correction of sagittal balance is associated with greater odds of discharge to home. These findings, coupled with the recognized implications of admission to a rehabilitation facility, will emphasize the importance of spine surgeons accounting for SVA into their surgical planning of MIS lumbar interbody fusions.

The Effect of Physical Therapy on Time to Discharge After Lumbar Interbody Fusion.

BACKGROUND: With a lesser degree of tissue destruction, patients undergoing minimally-invasive spine surgery are primed to benefit from early mobilization, which can further enhance recovery and hasten rehabilitation. We aimed to determine the role of physical therapy on earlier discharge after minimally-invasive transforaminal lumbar interbody fusion (TLIF). METHODS: Michigan Spine Surgery Improvement Collaborative (MSSIC) provided patients undergoing one- and two-level minimally-invasive TLIF for degenerative lumbar disease. The study population was divided into patients with a one-day length of stay (LOS 1), two days (LOS 2), and three or more days (LOS ≥ 3) to maintain three equal-time cohorts. On POD 0, physical therapy (or, in very rare circumstances, a spine-care-specialized nurse in patients arriving to the in-patient floors late after hours) must evaluate capacity to ambulate. RESULTS: Of the 101 patients, the median day of first ambulation statistically significantly increased from the LOS 1 to LOS ≥ 3 cohort (P = 0.007). Mean distance ambulated decreased from 156.5 ±â€¯123.1 feet in the LOS 1 group, 108.9 ±â€¯83.9 feet in the LOS 2 group, to 69.2 ±â€¯58.3 feet in the LOS ≥ 3 group (P = 0.002). Patient-reported outcomes did not differ among the three cohorts. Following a multivariable ordinal logistical regression controlling for disposition to rehab over home (ORadj = 5.47, P = 0.045), the odds of longer LOS decreased by 39% for every 50-feet ambulated (P = 0.002). CONCLUSIONS: Time to first ambulation independently increases the odds of earlier discharge, regardless of comorbidity burden and surgical determinants.

Assessment of radiographic and clinical outcomes of an articulating expandable interbody cage in minimally invasive transforaminal lumbar interbody fusion for spondylolisthesis.

OBJECTIVE The inability to significantly improve sagittal parameters has been a limitation of minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF). Traditional cages have a limited capacity to restore lordosis. This study evaluates the use of a crescent-shaped articulating expandable cage (Altera) for MIS TLIF. METHODS This is a retrospective review of 1- and 2-level MIS TLIF. Radiographic outcomes included differences in segmental and lumbar lordosis, disc height, evidence of fusion, and any endplate violations. Clinical outcomes included the numeric rating scale for leg and back pain and the Oswestry Disability Index (ODI) for low-back pain. RESULTS Thirty-nine patients underwent single-level MIS TLIF, and 5 underwent 2-level MIS TLIF. The mean age was 63.1 years, with 64% women. On average, spondylolisthesis was corrected by 4.3 mm (preoperative = 6.69 mm, postoperative = 2.39 mm, p < 0.001), the segmental angle was improved by 4.94° (preoperative = 5.63°, postoperative = 10.58°, p < 0.001), and segmental height increased by 3.1 mm (preoperative = 5.09 mm, postoperative = 8.19 mm, p < 0.001). At 90 days after surgery the authors observed the following: a smaller postoperative sagittal vertical axis was associated with larger changes in back pain at 90 days (r = -0.558, p = 0.013); a larger decrease in spondylolisthesis was associated with greater improvements in ODI and back pain scores (r = -0.425, p = 0.043, and r = -0.43, p = 0.031, respectively); and a larger decrease in pelvic tilt (PT) was associated with greater improvements in back pain (r = -0.548, p = 0.043). For the 1-year PROs, the relationship between the change in PT and changes in ODI and numeric rating scale back pain were significant (r = 0.612, p = 0.009, and r = -0.803, p = 0.001, respectively) with larger decreases in PT associated with larger improvements in ODI and back pain. Overall for this study there was a 96% fusion rate. Fourteen patients were noted to have endplate violation on intraoperative fluoroscopy during placement of the cage. Only 3 of these had progression of their subsidence, with an overall subsidence rate of 6% (3 of 49) visible on postoperative CT. CONCLUSIONS The use of this expandable, articulating, lordotic, or hyperlordotic interbody cage for MIS TLIF provides a significant restoration of segmental height and segmental lordosis, with associated improvements in sagittal balance parameters. Patients treated with this technique had acceptable levels of fusion and significant reductions in pain and disability.

Lateral Atlantoaxial Osteoarthritis: A Narrative Literature Review.

Lateral atlantoaxial osteoarthritis (AAOA), or C1-C2 lateral mass arthritis (LMA), is an unfamiliar degenerative cervical disease with a clinical presentation that markedly differs from subaxial spondylosis. The prevalence of LMA in the nonsurgical outpatient setting is 4%. Risk factors include age and occupation. The typical patient is between 50 and 90 years old, presents with upper cervical or occipital pain, has limited rotation, and has pain provocation during passive rotation to the affected side. Pain stems from degeneration of the lateral C1-C2 articulation and may be referred or radicular, through the greater occipital nerve. Although there is no consensus on diagnostic work-up, the disease is classically seen on the open-mouth odontoid radiograph. Computerized tomography, magnetic resonance imaging, bone scan, and diagnostic injections are also useful. Initial treatment is conservative, and upwards of two-thirds of LMA patients obtain lasting relief with noninvasive measures and injections. In patients with severe, recalcitrant pain, limited C1-C2 fusion offers satisfactory and reliable relief. The goals of this review article are to provide a synthesis of the literature on LMA, to offer a treatment approach to LMA, and to identify problems with the current state of knowledge on LMA.

Management of perisylvian arteriovenous malformations: a retrospective institutional case series and review of the literature.

OBJECT: Sylvian arteriovenous malformations (sAVMs) are challenging lesions of the central nervous system. The natural history of these unique lesions as well as clinical outcomes following treatment of sAVMs has been limited to case series owing to the rarity of these lesions. The authors present their experience with sAVMs and review the literature. METHODS: In accordance with the Henry Ford Institutional Review Board, medical records of patients with sAVMs treated from 2000 to 2012 were reviewed. Clinical data were retrospectively collected to calculate pre- and posttreatment modified Rankin Scale scores for all patients. RESULTS: The authors identified 15 patients with sAVMs who received treatment. Of these, 12 were female and 3 were male, and the average age at presentation was 39.6 ± 12.94 years (± SD). Two patients (13.3%) had Spetzler-Martin Grade I lesions, 6 patients (40%) had Grade II lesions, 5 patients (33.3%) had Grade III lesions, and another 2 (13.3%) harbored Grade IV arteriovenous malformations (AVMs). According to the Sugita classification, 6 patients (40%) had medial lesions, 6 (40%) had lateral lesions, 2 (13.3%) had deep lesions, and 1 patient (6.67%) had a pure sAVM. Eight patients (53.3%) underwent stereotactic radiosurgery while 7 patients (46.7%) had microsurgical resection; 1 patient underwent surgical extirpation after incomplete response following radiosurgery. After treatment, 9 patients were unchanged from pretreatment (60%), 3 patients worsened, and 2 patients had improved functional outcome (20% and 13.3%, respectively). The authors' literature search yielded 348 patients with sAVMs, most of them harboring Spetzler-Martin Grade II and III lesions. Approximately 98% of the patients underwent resection with excellent outcomes. CONCLUSIONS: While the ideal choice of therapeutic modality for cerebral AVMs remains controversial in light of the recent publication of the ARUBA (A Randomized trial of Unruptured Brain AVMs) trial, a multidisciplinary treatment approach for the management of sAVMs can lead to acceptable neurological outcome.