title: Spondylolysis of L2 in identical twins.
abstract: OBJECTIVE
  To discuss the presence of spondylolysis at L2 in identical twins.
  
  
  METHODS
  Twin 61-year-old brothers reported insidious low back pain (LBP) of relatively recent onset. Both engaged in running as their main form of exercise. One had spondylolisthesis and history of significant traumatic incident; the other had no spondylolisthesis but a much more strenuous running regimen.
  
  
  RESULTS
  Both patients underwent a course of chiropractic treatment for mechanical LBP and reported a 50% overall improvement in symptoms.
  
  
  CONCLUSIONS
  Spondylolysis at L2 is uncommon, and although a familial component regarding weakness of the pars interarticularis has been demonstrated in the literature, spondylolysis at L2 in twins is extremely rare. Questions remain regarding the cause of spondylolisthesis in patients.
authors.affiliation: Welsh Institute of Chiropractic, University of Glamorgan, Pontypridd CF37 1DL, Wales, UK. kjyoung@glam.ac.uk
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Young
authors.forename: Winfred
authors.initials: W
authors.lastname: Koning
mesh_terms: D004200:Diseases in Twins; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D026882:Manipulation, Chiropractic / Q000379:methods*; D008875:Middle Aged; D011859:Radiography; D013168:Spondylolisthesis / Q000628:therapy; D013169:Spondylolysis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome