Anatomic Considerations of Intervertebral Disc Perspective in Lumbar Posterolateral Approach via Kambin's Triangle: Cadaveric Study

STUDY DESIGN: Anatomical study. PURPOSE: To evaluate the anatomy of intervertebral disc (IVD) area in the triangular working zone of the lumbar spine based on cadaveric measurements. OVERVIEW OF LITERATURE: The posterolateral percutaneous approach to the lumbar spine has been widely used as a minimally invasive spinal surgery. However, to our knowledge, the actual perspective of disc boundaries and areas through posterolateral endoscopic approach are not well defined. METHODS: Ninety-six measurements for areas and dimensions of IVD in Kambin's triangle on bilateral sides of L1–S1 in 5 fresh human cadavers were studied. RESULTS: The trapezoidal IVD area (mean±standard deviation) for true working space was 63.65±14.70 mm2 at L1–2, 70.79±21.88 mm2 at L2–3, 99.03±15.83 mm2 at L3–4, 116.22±20.93 mm2 at L4–5, and 92.18±23.63 mm2 at L5–S1. The average dimension of calculated largest ellipsoidal cannula that could be placed in IVD area was 5.83×11.02 mm at L1–2, 6.97×10.78 mm at L2–3, 9.30×10.67 mm at L3–4, 8.84×13.15 mm at L4–5, and 6.61×14.07 mm at L5–S1. CONCLUSIONS: The trapezoidal perspective of working zone of IVD in Kambin's triangle is important and limited. This should be taken into consideration when developing the tools and instruments for posterolateral endoscopic lumbar spine surgery.

Outcomes of Fluoroscopically Guided Lumbar Transforaminal Epidural Steroid Injections in Degenerative Lumbar Spondylolisthesis Patients

STUDY DESIGN: A prospective cohort. PURPOSE: To report the short and long term outcomes of fluoroscopically guided lumbar transforaminal epidural steroid injection (TFESI) in degenerative lumbar spondylolisthesis (DLS) patients. OVERVIEW OF LITERATURE: TFESI has been widely used for the treatment of lumbosacral radicular pains. However, to our knowledge, there has been no study which has evaluated the outcomes of TFESI in patients with DLS. METHODS: The DLS patients received fluoroscopically guided lumbar TFESI with 80 mg of methylprednisolone and 2 mL of 1% lidocaine hydrochloride. Patients were evaluated by an independent observer before the initial injection, at 2 weeks, at 6 weeks, at 3 months, and at 12 months after the injections. Visual analog scale (VAS), Roland 5-point pain scale, standing tolerance, walking tolerance, and patient satisfaction scale were evaluated for outcomes. RESULTS: Thirty three DLS patients treated with TFESI, who were completely followed up, were included in this study. The average number of injections per patient was 1.9 (range from 1 to 3 injections per patient). Significant improvements in VAS and Roland 5-point pain scale were observed over the follow up period from 2 weeks to 12 months. However, the standing and walking tolerance were not significantly improved after 2 weeks. At 2 weeks, the patient satisfaction scale was highest, although, these outcomes declined with time. The DLS patients with one level of spinal stenosis showed significantly better outcome than the DLS patients with two levels of spinal stenosis. Five patients (13%) underwent surgical treatment during the 3 to 12 months follow up. CONCLUSIONS: TFESI provides short term improvements in VAS and Roland 5-point pain scale, standing tolerance, walking tolerance and patient satisfaction scale in DLS patients. In the long term, it improves VAS but limits the improvements in Roland 5-point pain scale, standing tolerance, walking tolerance and patient satisfaction scale.

Relationship of Facet Tropism with Degeneration and Stability of Functional Spinal Unit

PURPOSE: The authors investigated the effect of lumbar facet tropism (FT) on intervertebral disc degeneration (DD), facet joint degeneration (FJD), and segmental translational motion. MATERIALS AND METHODS: Using kinetic MRI (KMRI), lumbar FT, which was defined as a difference in symmetry of more than 7degrees between the orientations of the facet joints, was investigated in 900 functional spinal units (300 subjects) in flexion, neutral, and extension postures. Each segment at L3-L4, L4-L5, and L5-S1 was assessed based on the extent of DD (grade I-V) and FJD (grade 1-4). According to the presence of FT, they were classified into two groups; one with FT and one with facet symmetry. For each group, demographics, DD, FJD and translational segmental motion were compared. RESULTS: The incidence of FT was 34.5% at L3-L4, 35.1% at L4-L5, and 35.2% at L5-S1. Age and gender did not show any significant relationship with FT. Additionally, no correlation was observed between DD and FT. FT, however, wasfound to be associated with a higher incidence of highly degenerated facet joints at L4-L5 when compared to patients without FT (p < 0.01). Finally, FT was not observed to have any effects upon translational segmental motion. CONCLUSION: No significant correlation was observed between lumbar FT and DD or translational segmental motion. However, FT was shown to be associated significantly with the presence of high grades of FJD at L4-L5. This suggests that at active sites of segmental motion, FT may predispose to the development of facet joint degeneration.