Bilateral Pars Defects at the L4 Vertebra Result in Increased Degeneration When Compared With Those at L5: An Anatomic Study

Abstract

Background Cadaveric studies have examined disc degeneration at the L4-L5 and L5-S1 motion segments; however, we are not aware of another study that has examined the relationship between bilateral spondylolysis and its effect on degenerative disc disease at those levels. This may have been overlooked by researchers owing to the majority of spondylolysis occurring at the L5 vertebra. Questions/purposes Using osteologic specimens from a collection that included individuals who died in one city in the USA between 1893 and 1938, we asked: (1) do specimens with bilateral spondylolysis (bilateral pars defects) have increased levels of disc degeneration, at their respective motion segments, when compared with matched controls without spondylolysis, and (2) is the finding of a bilateral pars defect associated with more severe arthritis at L4-L5 than at L5-S1? Methods An observational study was performed on 665 skeletal lumbar spines from the Hamann-Todd Osteologic Collection at the Cleveland Museum of Natural History (Cleveland, OH, USA). The specimens included 534 males and 131 females ranging from 17 to 87 years old, with a nearly bell-shaped distribution of ages for males and a larger proportion of younger ages in the female specimens. Of those with spondylolysis, 81 had a defect at L5 and 14 had a defect at L4. The gross specimens were examined subjectively for evidence of arthrosis. At the time of examination, specific attention was not paid to the coexisting presence or absence of spondylolysis nor was the examiner blinded to the age of the specimens. Disc degeneration was measured by the classification of Eubanks et al., a modified version of the Kettler and Wilke classification. Linear regression was performed to derive a formula that would predict the amount of disc degeneration at L4-L5 and L5-S1 for the normal control population given a specimen's age, sex, and race. We then used this formula to evaluate the difference in disc degeneration at the corresponding level of the pars defect that is greater Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research 1 editors and board members are on file with the publication and can be viewed on request. Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained. This work was performed at the University Hospitals Case Medical Center and the Cleveland Museum of Natural History, Cleveland, OH, USA. P. T. McCunniff (&), Clinical Orthopaedics and Related Research ®A Publication of The Association of Bone and Joint Surgeons® than the pr...

Straighter low lumbar curvature in isthmic spondylolisthesis at L4

“…However, DDG, SR, and ODI showed no significant differences in our study, even when accounting for age. This result was discordant with the conclusions and speculations of previous anatomical studies [6]. The disagreement was caused mainly by difference in study subjects; the subjects in our study were in urgent need of interventions while those in previous anatomical studies had no clinical symptoms or only mild symptoms.…”

“…Grobler et al [5] performed biomechanical experiments on six specimens to confirm that the lesion segment was more unstable when spondylolytic lesions occurred at L4 than at L5. Through an observational study on 665 skeletal lumbar spines, McCunniff et al [6] found that patients with spondylolysis at L4 also displayed a greater degree of degeneration of the disc below the level of the associated isthmic defect than those with spondylolysis at L5, suggesting that there was a greater degree of degenerative disc disease and clinical symptoms among people with spondylolysis at L4. Most patients with spondylolysis progressed to IS when they had obvious clinical symptoms [7].…”

Straighter low lumbar curvature in isthmic spondylolisthesis at L4

“…However, DDG, SR, and ODI showed no signi cant differences in our study, even when accounting for age. This result was discordant with the conclusions and speculations of previous anatomical studies [6]. The disagreement was caused mainly by difference in study subjects; the subjects in our study were in urgent need of interventions while those in previous anatomical studies had no clinical symptoms or only mild symptoms.…”

“…Grobler et al [5] performed biomechanical experiments on six specimens to con rm that the lesion segment was more unstable when spondylolytic lesions occurred at L4 than at L5. Through an observational study on 665 skeletal lumbar spines, McCunniff et al [6] found that patients with spondylolysis at L4 also displayed a greater degree of degeneration of the disc below the level of the associated isthmic defect than those with spondylolysis at L5, suggesting that there was a greater degree of degenerative disc disease and clinical symptoms among people with spondylolysis at L4. Most patients with spondylolysis progressed to IS when they had obvious clinical symptoms [7].…”

Straighter Low Lumbar Curvature in Isthmic Spondylolisthesis at L4

“…Grobler et al [5] performed biomechanical experiments on six specimens to confirm that the lesion segment was more unstable when spondylolytic lesions occurred at L4 than at L5. Through an observational study on 665 skeletal lumbar spines, McCunniff et al [6] found that patients with spondylolysis at L4 also displayed a greater degree of degeneration of the disc below the level of the associated isthmic defect than those with spondylolysis at L5, suggesting that there was a greater degree of degenerative disc disease and clinical symptoms among people with spondylolysis at L4.…”