title: Prevalence of anatomic impediments to interlaminar lumbar epidural steroid injection.
abstract: OBJECTIVE
  To determine the prevalence of anatomic impediments to interlaminar lumbar epidural steroid injection (LESI) in a community-based population.
  
  
  METHODS
  Cross-sectional observational study.
  
  
  METHODS
  Community-based.
  
  
  METHODS
  Older adults (N=333) sampled irrespective of back pain status.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Computed tomography evaluation of 5 potential anatomic impediments to interlaminar LESI at the L2-S1 spinal levels, including (1) ligamentum flavum (LF) calcification, (2) interspinous ligament (ISL) calcification, (3) spinous process (SP) contact, (4) the absence of epidural fat in the posterior epidural space, and (5) the presence of fat density superficial to the LF in the midsagittal plane. Independent variables included age, sex, body mass index (BMI), and current smoking.
  
  
  RESULTS
  LF and ISL calcifications were prevalent in 3% to 7% and 2% to 3% of spinal levels, respectively, without significant differences by spinal level. SP contact was most common at the L4-5 level (22%). Absence of posterior epidural fat was very common at L5-S1 (65%), but infrequent at other levels. The presence of midline fat density superficial to LF was most common at L5-S1 (55%). The prevalence of LF calcification, ISL calcification, and SP contact increased with age, but the prevalence of absence of posterior epidural fat and the presence of a midline fat density superficial to LF did not. Sex and smoking status were not associated with the prevalence of anatomic impediments, but higher BMI was associated with a lower prevalence of absence of posterior epidural fat.
  
  
  CONCLUSIONS
  Anatomic impediments to interlaminar LESI were common in this community-based population, particularly at the L5-S1 spinal level. Because of the high overall prevalence of anatomic impediments, and differences in prevalence by spinal level, knowledge of the distribution and frequency of these impediments may aid in aspects of decision-making for the interventional spine physician.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA.
authors.forename: Farah
authors.initials: F
authors.lastname: Hameed
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: James
authors.initials: J
authors.lastname: Rainville
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Pradeep
authors.initials: P
authors.lastname: Suri
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D002114:Calcinosis / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007268:Injections, Epidural; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed
chemical_list: D005938:Glucocorticoids