L5 Pedicle Length Is Increased in Subjects With Spondylolysis: An Anatomic Study of 1072 Cadavers

Abstract

Background In spondylolisthesis, it is believed that as L5 slips on S1, the pedicle may become elongated in response to the instability in an attempt to bridge the defect. Whether patients with spondylolysis, which is largely developmental, also develop elongation of the pedicles is unknown. Questions/purposes The purpose of this study is to evaluate and quantify the increase in L5 pedicle length in subjects with spondylolysis as compared with normal healthy subjects. Methods Nine hundred fifty-two human cadaveric specimens without spondylolysis and 120 specimens with spondylolysis from the Hamann-Todd Osteological Collection were examined by a single examiner. Baseline data, including age, sex, and race of specimens, were collected. Digital calipers were used to measure the pedicle lengths at the L5 level. Linear regression analysis was performed to compare the L5 pedicle lengths in healthy patients and patients with spondylolysis. Results Linear regression showed a significant association of increased L5 pedicle length in subjects with spondylolysis. The average L5 pedicle length in subjects with spondylolysis was greater compared with subjects without spondylolysis. In spondylolytic specimens, pedicles start to elongate after the age of 40 years. The pedicle lengths increase progressively from 5.6 mm at 40 years to 6.7 mm at 80 years with a 1% to 3% increment every decade. The pedicle lengths showed little variation in specimens from healthy subjects. Conclusions In spondylolytic specimens, there is progressive elongation of L5 pedicle length after the third decade. An increase in L5 pedicle length in all age groups compared with the specimens from healthy subjects suggests that pathologic changes occur in bony anatomy of L5 vertebrae as early as adolescence when the condition develops.

Pedicle Length and Degree of Slip in Lumbosacral Isthmic Spondylolisthesis

“…The results of the present study add to the limited available data on the morphology of the L5 pedicle in subjects with spondylolytic spondylolisthesis 5,6 . Anatomic pedicle changes in spondylolytic spondylolisthesis may reflect remodeling, greater changes being associated with a greater degree of slip.…”

“…In an anatomic study of 1072 cadavers, the L 5 pedicle length in 120 specimens with spondylolysis was compared with that of 952 controls without spondylolysis. It was found that the average pedicle length was greater in subjects with spondylolysis, and that elongation occurred after 40 years of age. However, this study was limited to cadavers, and the results and observations may not be directly applicable to living humans.…”

“…In an anatomic study of 1072 cadavers, Bajwa et al . noted that L 5 pedicle length is increased in subjects with pars interarticularis defects. In another study by Choi et al ., the pedicle was noted to be elongated and to have a wider angle in patients with L 5 −S 1 spondylolytic spondylolisthesis.…”

“…This notion is supported by sagittal magnetic resonance (MR) images, which demonstrate an increased sagittal diameter following dorsal subluxation of the posterior elements. In an anatomic study of 1072 cadavers, Bajwa et al noted that L5 pedicle length is increased in subjects with pars interarticularis defects 5 . In another study by Choi et al, the pedicle was noted to be elongated and to have a wider angle in patients with L5−S1 spondylolytic spondylolisthesis 6 .…”

Phenotypic characterization of Slc26a2 mutant mice reveals a multifactorial etiology of spondylolysis

“…30 This finding is consistent with the previous study where a total of 509 fetal specimens were examined and displayed neither isthmic crack nor separate neural arch. 15,[47][48][49][50] One good example is a study where the transverse interfacet distance was measured among 39 patients with spondylolysis and compared to 42 adults without spondylolysis. A, Representative calcein double labeling images of isthmus in the junctional region (boxed area) between the ventral and dorsal part of the vertebra.…”