Volar and Dorsal Blood Supply to the Lunate: A Cadaveric Study.

Although various studies have proposed vascular and mechanical factors, the etiology of Kienböck disease is unknown. Kienböck theorized that lunatomalacia resulted from traumatic disruption of blood supply and bony nutrition to the lunate. Extraosseous supply to the lunate, as far as volar or dorsal vessels are concerned, is still controversial. This study evaluated the extraosseous nutrient foramina from the dorsal and volar aspects of lunate specimens. A total of 913 specimens from the Hamann-Todd Osteological Collection in Cleveland, Ohio, were examined. The nutrient artery foramina on left and right lunate specimens were examined from dorsal and volar aspects. The number of nutrient artery foramen was tabulated. Age, sex, and race data were collected. Specimens were divided into groups according to the number of nutrient artery foramina, and the dorsal and volar foramina were compared. The average number of foramina on the dorsal aspect of the lunate (1.71) was greater than the volar aspect (1.64), except in specimens younger than 35 years. A greater number of specimens had 3 or more foramina on the dorsal side compared with the volar aspect. Based on this study, there was significant contribution of dorsal arterial vessels to the blood supply of lunate specimens older than 35 years, which contrasts with findings in earlier studies. The disruption of dorsal intercarpal and radiocarpal ligaments leading to the disruption of the dorsal arterial arches may contribute to vascular insufficiency of the lunate and should be evaluated further in the etiopathogenesis of Kienböck disease. [Orthopedics. 2021;44(2):e243-e247.].

Cervicothoracic Pedicle Morphometry: Using an Osteological Collection to Characterize Trends in Pedicle Size.

Pedicle screws are a common treatment option for spinal instability. Despite their popularity, pedicle screws carry the risk of transpedicular violation with subsequent neural and vascular damage. This study measured the pedicle dimensions of 500 dry specimens in an osteological collection. The data provide the orthopedic spine surgeon with an accurate measure of pedicle morphometry in light of previously limited and contradictory results. The study demonstrates that pedicle height at the cervicothoracic junction tends to increase with body height, particularly for females. Additionally, T1 pedicle width is smaller for females than males and, for males, tends to decrease with increasing body weight. These results are valuable to the spine surgeon because they suggest that taller patients may afford a larger margin for error in the vertical plane. However, they also demonstrate that heavier patients do not have wider pedicles and thus cannot be assumed to tolerate or require larger-diameter screws. (Journal of Surgical Orthopaedic Advances 27(1):33-38, 2018).

Spondylolysis and End Plate Arthrosis at L5-S1: A Cadaveric Study.

This study examined the effect of bilateral and unilateral L5 pars defects on the degree of disk degeneration at the L5-S1 level in cadaveric specimens. An observational study was performed of 690 cadaveric specimens selected at random. These specimens represent individuals who died between 1893 and 1938. The study included 558 male and 132 female cadavers. Of the 120 specimens with L5 spondylolysis, 95 cases were bilateral and 25 were unilateral. The remaining 544 specimens were used as the control cohort. Degenerative disk disease was measured by the classification of Eubanks et al. According to this classification, degenerative disk disease was graded from no arthrosis (grade 0) to complete ankylosis (grade IV). Linear regression analysis corrected for age, sex, and race showed that subjects with bilateral spondylolysis at L5 had a statistically significant increase in the amount of disk degeneration (P=.02) compared with those with unilateral lesions. Student's t tests showed significant differences (P<.001 and P=.002, respectively) in the amount of degeneration seen with both bilateral and unilateral spondylolysis above what would be predicted in the normal control population. A positive correlation was found between the number of pars defects at L5 and the degree of disk degeneration at L5-S1. These results support the idea that individuals with spondylolysis at these levels may be at increased risk for development of low back pain and reduced quality of life. [Orthopedics. 2017; 40(1):e59-e64.].

Calcaneocuboid Joint Arthritis of the Midfoot Precedes Tibiotalar Joint Arthritis.

Surgical models have best shown the relationship between ankle and mid-foot osteoarthritis, although findings regarding the calcaneocuboid joint have varied. To the authors' knowledge, no studies have evaluated the relationship between degenerative changes across the tibiotalar and calcaneocuboid joints. The goal of this study was to determine whether such a relationship exists and which joint degenerates first. A single examiner evaluated 694 tibiotalar and calcaneocuboid joints to determine the presence of osteoarthritis. Multiple linear regression analysis was conducted with a standard P value cutoff (P<.05) and 95% confidence interval. The average incidence of tibiotalar and calcaneocuboid osteoarthritis in specimens older than 40 years was compared with the incidence in those 40 years and younger. A positive correlation between tibiotalar and calcaneocuboid osteoarthritis was noted. African-American subjects were less likely than white subjects to have tibiotalar osteoarthritis. The finding of right and left tibiotalar and calcaneocuboid osteoarthritis in subjects 40 years and younger showed that midfoot arthritis was significantly more common than arthritis of the ankle. The prevalence of calcaneocuboid osteoarthritis remains stable after 40 years of age, and the prevalence of tibiotalar osteoarthritis approaches that of calcaneocuboid osteoarthritis. Calcaneocuboid osteoarthritis precedes tibiotalar osteoarthritis. Altered biomechanics involved in calcaneocuboid osteoarthritis are transferred to the tibiotalar joint, leading to tibiotalar osteoarthritis as the subject ages. Early education, surveillance, physical therapy, shoe adjustment, and orthotics may help to reduce the forces across the midfoot and prevent ankle arthritis in the long term. [Orthopedics. 2016; 39(6):e1112-e1116.].

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

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 than the predicted amount for a control without spondylolysis. This allowed us to conclude that any significant differences found between the L4-L5 and L5-S1 cohorts were attributable to factors not simply inherent to their functional position in the spine of an individual without a bilateral pars defect. RESULTS: L4 spondylolysis and L5 spondylolysis showed greater amounts of degeneration compared with that of matched controls (L4 controls: mean = 1.52, SD = 0.74; L4 spondylolysis: mean = 3.21, SD = 0.87; p < 0.001; L5 controls: mean = 0.97, SD = 0.48; L5 spondylolysis: mean = 2.06, SD = 0.98; p < 0.001). When we controlled for the expected amount of degenerative disc disease at each level in controls, the observed degeneration was more severe at L4-L5 than at L5-S1 (p = 0.008, R-squared = 18.6). CONCLUSIONS: L4-L5 and L5-S1 bilateral spondylolysis groups had increased presence of degenerative disc disease compared with those without bilateral spondylolysis. For the same degree of spondylolysis, the observed amount of disc degeneration was greater at the L4-5 motion segment compared with L5-S1. CLINICAL RELEVANCE: Although not as common as the spondylolysis at L5-S1, we believe that our findings support that patients with L4-L5 spondylolysis can expect a greater degree of degenerative disc disease and increasing clinical symptoms. Multiple factors in the sacropelvic geometry of an individual, facet morphologic features at L4-L5, and the absence of the iliolumbar ligament at this level are possible contributing factors to the findings of this study.

Pedicle Morphometry of Lumbar Vertebrae: Male, Taller, and Heavier Specimens Have Bigger Pedicles.

STUDY DESIGN: An anatomic study of pedicle dimensions was performed for lumbar vertebrae from American subjects. OBJECTIVE: To quantify the dimensions of the lumbar pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. SUMMARY OF BACKGROUND DATA: Transpedicular screw fixation allows for segmental instrumentation into multiple vertebrae across multilevel fusion area, offering considerable biomechanical advantage over the conventional hook and lateral mass fixation. Large variations in morphology from previous studies may be related to differences in demographics, sample size, and methodology. METHODS: For this study, L1-L5 vertebrae from 503 American human cadavers were directly measured with a digital caliper. Examiner measured each vertebra to determine medial-lateral pedicle width (PW) and cranial-caudal pedicle height (PH). Demographic information regarding age, sex, and race, as well as body height and weight, was available for all 503 subjects. RESULTS: PH decreased in size caudally down the lumbar spine, but PW increased in size. The largest PH was at the L1 level with a mean of 15.75 mm. The widest PW was at the L5 level with a mean of 18.33 mm. Males have larger pedicles than females for all lumbar levels. The tallest and heaviest groups generally had larger pedicles than the shorter and lighter groups, respectively. Age and race did not consistently affect pedicle dimension in a statistically significant manner. CONCLUSION: Our large-scale study of American specimens characterized the relationship between pedicle dimensions and a variety of demographic factors such as age, sex, body height, and weight. With substantial statistical power, the current study showed that male, taller, and heavier individuals had larger lumbar pedicles. LEVEL OF EVIDENCE: 3.

Lumbar degenerative disc disease and tibiotalar joint arthritis: a 710-specimen postmortem study.

Research has associated lumbar spinal disease with lower extremity arthrosis. These studies focused solely on the lumbar spine's connection with hip or knee pathology, failing to investigate potential ankle relationships. We specifically explored the interplay between lumbar disc degeneration and tibiotalar joint arthritis. Lumbar disc degeneration and tibiotalar joint arthritis was graded 0 to 4, according to osteophytosis of the vertebral rim and talar surface in 710 randomly selected cadaveric specimens. We corrected for confounding factors of age, sex, race, and height. A significant association was found between lumbar disc degeneration and tibiotalar joint arthritis (P < .01). Lumbar disc degeneration encompassing 3 intervetebral discs demonstrated the highest odds for development of severe tibiotalar joint arthritis. Severe lumbar degenerative disc disease was more prevalent than severe tibiotalar joint arthritis in individuals age 20 years and older. Furthermore, the presence of severe lumbar degeneration significantly predisposes individuals to the development of severe ankle arthritis (P < .05). Gait changes resulting from disc degeneration or neural compression in the lumbar spine may play a role in ankle osteoarthritis development. This association must be considered when treating patients with lumbar disc degeneration and leg pain.

Lower thoracic pedicle morphometry: male, taller, and heavier specimens have bigger pedicles.

STUDY DESIGN: An anatomic study of pedicle dimensions was performed for lower thoracic vertebrae from American human subjects. OBJECTIVE: To quantify the dimensions of the lower thoracic pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. SUMMARY OF BACKGROUND DATA: Transpedicular screw fixation allows for segmental instrumentation into multiple vertebrae across multilevel fusion area, offering considerable biomechanical advantage over the conventional hook and lateral mass fixation. Large variations in morphology from previous studies may be related to differences in demographics, sample size, and methodology. METHODS: For this study, T7-T12 vertebrae from 503 American human cadavers were directly measured with a digital caliper. Examiner measured each vertebra to determine medial-lateral pedicle width and cranial-caudal pedicle height. Demographic information regarding age, sex, and race, as well as body height and weight, was available for all 503 subjects. RESULTS: Both pedicle height and pedicle width generally increased in size caudally down the lower thoracic spine. The highest pedicle height was at the T12 level with a mean of 17.08 mm. The widest pedicle width was at the T11 level with a mean of 9.31 mm. Males have larger pedicles than females for all upper thoracic levels. The tallest and heaviest groups had larger pedicles than the shorter and lighter groups, respectively. Age and race did not consistently affect pedicle dimension in a statistically significant manner. CONCLUSION: Our large-scale study of American specimens characterized the relationship between pedicle dimensions and a variety of demographic factors such as age, sex, body height and weight. With substantial statistical power, this study showed that male, taller, and heavier individuals had larger pedicles. LEVEL OF EVIDENCE: N/A.

Defining hyoplasia of the atlas: a cadaveric study.

STUDY DESIGN: Cadaveric study. OBJECTIVE: To define congenital hypoplasia of the atlas. SUMMARY OF BACKGROUND DATA: Little has been written about hypoplasia of the atlas and it is usually described in the setting of other skeletal dysplasias or syndromes. METHODS: A total of 543 cervical spine specimens were randomly selected from the Hamann-Todd collection. Sagittal and coronal diameters of the atlas, axis, and C3 (when available), and the dens diameter were measured using digital calipers. Correction for modern size and radiographical magnification was performed. Hypoplasia of the atlas was defined as the lowest 2.5% of measurements. The correlation between inner sagittal diameters at C1 and C3 was calculated. RESULTS: The mean C1 inner sagittal diameter was 30.8 ± 2.4 mm (range, 23.5-38.1 mm). We defined C1 hypoplasia as an inner sagittal diameter value representing the smallest 2.5% of subjects. Because the mean was 30.8 mm, hypoplasia was defined as a diameter of ≤26.1 mm or less. Correcting for size and magnification of radiographs, hypoplasia is defined as an inner sagittal diameter of the atlas of 28.9 mm. Approximately 10% of cases had a dens that occupied more than 40% of the spinal canal at C1, thus not following Steel's Rule of Thirds. There was only a moderate correlation between the spinal canal diameter at C1 and at C3 (r = 0.483, N = 345; P < 0.001). CONCLUSION: With an inner sagittal diameter of 26 mm or less, one may describe the atlas as hypoplastic. Ten percent of the specimens had an odontoid process that occupied more than 40% of the spinal canal at C1. There was little correlation between the inner sagittal diameter at C1 and the diameter at C3. LEVEL OF EVIDENCE: N/A.

Pedicle morphometry of upper thoracic vertebrae: an anatomic study of 503 cadaveric specimens.

STUDY DESIGN: An anatomic study of pedicle dimensions was performed for upper thoracic vertebrae from American human subjects. OBJECTIVE: To quantify the dimensions of the upper thoracic pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. SUMMARY OF BACKGROUND DATA: Transpedicular screw fixation allows for segmental instrumentation into multiple vertebrae across multilevel fusion area, offering considerable biomechanical advantage over the conventional hook and lateral mass fixation. Large variations in morphology from previous studies may be related to differences in demographics, sample size, and methodology. METHODS: For this study, T1-T6 vertebrae from 503 American human cadavers were directly measured with a digital caliper. Examiner measured each vertebra to determine medial-lateral pedicle width and cranial-caudal pedicle height. Demographic information regarding age, sex, and race, as well as body height and weight, was available for all 503 subjects. RESULTS: Pedicle height generally increased in size caudally down the upper thoracic spine, but the highest pedicle height was at the T3 level with a mean of 12.25 mm. Pedicle width displayed a narrowing pattern moving down. The widest pedicle width was at the T1 level with a mean of 8.66 mm. The 2 older age groups had larger pedicles than the 2 younger age groups. Males have larger pedicles than females for all upper thoracic levels. The tallest and heaviest groups had larger pedicles than the shorter and lighter groups, respectively. Race was not a significant factor in affecting pedicle dimension. CONCLUSION: Our large-scale study of American specimens characterized the relationship between pedicle dimensions and a variety of demographic factors such as age, sex, body height, and weight. With substantial statistical power, this study showed that male, older, taller, and heavier individuals had larger pedicles. LEVEL OF EVIDENCE: N/A.

Femoral head asymmetry and coxa magna: anatomic study.

BACKGROUND: Coxa magna, the asymmetrical circumferential enlargement of the femoral head, is an important sequela of pediatric disorders such as Legg-Calvé-Perthes disease. Definitions vary because of lack of controls and a scarcity of research on the distribution of the femoral head asymmetry. This study aims at defining the normal distribution of asymmetry between the left and the right femoral head and neck in the population and how demographics affect these properties. The study also looked at the distribution of side dominance (left or right). METHODS: This study measured 230 paired femurs from individuals (20 to 40 y old) distributed for sex and ethnicity. The height and weight of the individuals were also recorded. The femoral head diameter and minimal femoral neck diameter in the anteroposterior view were measured on each paired femurs. The absolute and percent differences were determined to define asymmetry. RESULTS: Most of the population fell within 3% of asymmetry for the femoral head and 4% for the femoral neck. The maximum head percent asymmetry was 7.4%. Absolute difference in millimeters to percent asymmetry showed a ratio of 2:1 for the femoral head and 3:1 for the femoral neck. African Americans showed greater femoral head symmetry and a bias toward left-sided femoral head and neck enlargement when compared with their white counterparts. CONCLUSIONS: There was a high degree of symmetry between the left and right femoral heads and necks, which supports definitions found in the literature that define coxa magna above 10%. This study defines asymmetry in the femoral head in the normal population, which will help to define a quantitative definition of coxa magna.

Disk degeneration in lumbar spine precedes osteoarthritic changes in hip.

It is not clear whether spinal degeneration leads to hip arthritis, or hip arthritis leads to spinal degeneration. We conducted a study to determine which degenerative process precedes the other. We examined 340 cadaveric human specimens from the Hamann-Todd Osteological Collection (Cleveland, Ohio). Lumbar endplate degeneration was graded on a scale of 0 to 4, and hip degeneration on a scale of 0 to 3. Linear regression was used to analyze the relationship between hip osteoarthritis (OA) and lumbar degenerative disk disease (DDD). Exact tests were used to identify differences in each age group. Hip OA was significantly associated with endplate degeneration at the L1, L3, and L5 levels (P<.02). Of the specimens younger than 29 years, 35% had evidence of DDD in at least 1 lumbar level, and 17% of hip OA changes. At 70 years, 100% of the specimens had evidence of DDD and 50% of hip OA changes. There was a significant association between lumbar DDD and hip OA changes (P<.05). Early lumbar DDD was twice as common as hip OA changes in the early 20s age range. These findings suggest that lumbar degeneration precedes hip degeneration and may be a causative factor for hip OA.

Does chronic warfarin cause increased blood loss and transfusion during lumbar spinal surgery?

BACKGROUND CONTEXT: The use of oral anticoagulation therapy such as warfarin is projected to increase significantly as the population ages and the prevalence of cardiovascular disease increases. Current recommendations state that warfarin be discontinued before surgery and the international normalized ratio (INR) normalized. PURPOSE: To determine if stopping warfarin 7 days before surgery and correcting INR had any effect on intraoperative blood loss or the requirements for blood product transfusion. STUDY DESIGN/SETTING: This was a retrospective cohort study in a high-volume tertiary care center. PATIENT SAMPLE: Sample comprised 263 consecutive patients who underwent elective lumbar spinal surgery. OUTCOME MEASURE: The outcome measures were intraoperative blood loss, intraoperative blood transfusion, postoperative blood transfusion, and the number of blood products transfused. METHODS: The records of patients undergoing elective spinal surgery were analyzed for patient demographic data, comorbidities, coagulation panel laboratory findings, operative characteristics, blood loss, and blood transfusion requirements. These included patients undergoing full laminectomies with or without posterolateral fusion and instrumentation. Patients on warfarin were analyzed for the mean dosage of warfarin and underlying pathology that required anticoagulation. All patients on warfarin had their anticoagulation therapy stopped 7 days before surgery and their INR checked preoperatively to confirm normalization. Both univariate and multiple linear regression analyses were performed. RESULTS: The patients on warfarin had a mean intraoperative blood loss of 839 mL compared with 441 mL for patients not on warfarin (p<.01). Multiple regression analysis determined that warfarin and number of spinal levels decompressed/fused/instrumented were predictors for increased blood loss (R(2)=0.37). Patients on warfarin also had increased postoperative blood transfusions (23.1% compared with 7.4%, p=.04). There was no significant difference between groups in terms of intraoperative blood transfusion or number of units transfused. CONCLUSIONS: Patients on chronic anticoagulation therapy with warfarin who have their therapy stopped 7 days before surgery and have their INR normalized still demonstrated increased intraoperative blood loss and requirement for postoperative transfusion. Surgeons should be aware of the increased propensity of these patients to bleed despite adherence to protocols and should attempt to mitigate this risk.

Application of a correlation between the lumbar Torg ratio and the area of the spinal canal to predict lumbar stenosis: a study of 420 postmortem subjects.

BACKGROUND: A cervical Torg ratio of 0.8 has been used as a screening tool to determine the presence of cervical spinal stenosis. However, there have been no studies done to define the Torg ratio in the lumbar spine for predicting lumbar spinal stenosis (LSS). Torg ratios have never been correlated with the actual calculated canal area as derived from anatomic specimens. The aim of this study was to provide an analysis of the utility of the lumbar Torg ratio for predicting LSS based on objective measurements of skeletal specimens. MATERIALS AND METHODS: 420 adult skeletal specimens from the Hamann Todd Collection in the Cleveland Museum of Natural History were selected. Digital calipers were used to measure the sagittal diameter (SCD), interpedicular distance, pedicle length, and vertebral body diameter. The canal area at each level was calculated using a geometric formula. A standard distribution curve for canal area and Torg ratio was created, and values that were that is less than the mean minus two standard deviations (SD) below the mean were considered stenotic. Regression analysis was performed to determine if the Torg ratio was correlated with canal area, and if a "below normal" Torg ratio was predictive of LSS. RESULTS: The Torg ratio for 2SD below the mean was defined as 0.43 at L1, 0.43 at L2, 0.41 at L3, 0.38 at L4, 0.37 at L5. Regression analysis revealed a significant association of the Torg ratio with canal area (p < 0.01). A Torg ratio that was less than the mean - 2SD predicted canal stenosis at L2, L3, L4, and L5 (p < 0.01). Using a Torg ratio of <0.5 predicted stenosis with a sensitivity of 86% and specificity of 52% at all lumbar levels. CONCLUSIONS: Based on the results of our study, we have defined the lower limit of the normal Torg ratio at each level. A Torg ratio of <0.5 predicts LSS and could be a useful radiological tool for LSS screening.

Is congenital bony stenosis of the cervical spine associated with congenital bony stenosis of the thoracic spine? An anatomic study of 1072 human cadaveric specimens.

SUMMARY OF BACKGROUND DATA: Tandem stenosis of the cervical and lumbar spine is known to occur in 5% of individuals with symptomatic neural compression in one region. However, the prevalence of concurrent cervical and thoracic stenosis is not known. Whether this relationship is due to an increased risk of degenerative disease in these individuals, or whether this finding is due to the tandem presence of a congenitally small cervical and thoracic canal is unknown. OBJECTIVES: To determine the prevalence of concurrent thoracic and cervical stenosis and whether the presence of stenosis in the cervical spine is associated with stenosis in the thoracic spine. STUDY DESIGN: A morphoanatomic study of the cervical and thoracic cadaveric spines. METHODS: A total of 1072 adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History were selected. Canal area at each level was also calculated using a geometric formula. A standard distribution for each level was created, and values that were 2 SD below mean were considered as being congenitally stenotic. Linear regression analysis was used to determine the association between the additive canal areas at all levels in the cervical and thoracic spine and to determine the association between the number of stenotic levels in the cervical and thoracic spine. Logistic regression was used to calculate odds ratios for concurrent cervical and thoracic stenosis. RESULTS: The prevalence of concurrent cervical and thoracic stenosis is 1%. A positive association was found between the additive areas of all cervical and thoracic levels (P<0.01). No association, however, was found between the number of stenotic thoracic and cervical levels (P=0.689). Log regression demonstrated no significant association (odds ratio <1) between stenosis in the thoracic and cervical spine. CONCLUSIONS: The area changes in the cervical spine correlate with area variations in the thoracic spine and the severity of stenosis in the thoracic spine increases as the levels of stenosis increase in the cervical spine. The presence of tandem cervical and thoracic stenosis does seem to be, in part, related to the tandem presence of a congenitally small cervical and thoracic canal.

Is lumbar stenosis associated with thoracic stenosis? A study of 1,072 human cadaveric specimens.

BACKGROUND CONTEXT: Tandem stenosis of the cervical and lumbar spine is known to occur in 5% to 25% of individuals with symptomatic neural compression in one region. However, the prevalence of concurrent lumbar and thoracic stenosis is not known. Whether this relationship is because of an increased risk of degenerative diseases in these individuals or because of the tandem presence of stenosis in lumbar and thoracic canal is unknown. PURPOSE: To determine the prevalence of concurrent lumbar and thoracic stenosis, and whether the presence of stenosis in the lumbar spine is associated with stenosis in the thoracic spine. STUDY DESIGN: A morphoanatomic study of lumbar and thoracic cadaveric spines. METHODS: One thousand seventy-two adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History were selected. Canal area at each level was also calculated using a geometric formula. A standard distribution for each level was created, and values that were 2 standard deviations below mean were considered as being stenotic. Linear regression analysis was used to determine the association between the additive canal areas at all levels in the lumbar and thoracic spine and between the number of stenotic lumbar and thoracic levels. Logistic regression was used to calculate the odds ratios (OR) for concurrent lumbar and thoracic stenosis. RESULTS: The prevalence of concurrent lumbar and thoracic stenosis is 1.42%. A positive association was found between the additive areas of all lumbar and thoracic levels (p<.01). No association, however, was found between the number of stenotic lumbar and thoracic levels (p=.7). Log regression demonstrated no significant association (OR <1) between stenosis in the lumbar and thoracic spine. CONCLUSIONS: The stenosis of the lumbar spine is not associated with the thoracic stenosis. Thus, stenosis in lumbar and thoracic levels does not seem to be contributed by tandem stenosis.

Establishment of parameters for congenital stenosis of the cervical spine: an anatomic descriptive analysis of 1,066 cadaveric specimens.

PURPOSE: Congenital cervical stenosis (CCS) occurs when the bony anatomy of the cervical canal is smaller than expected in the general population predisposing an individual to symptomatic neural compression. No studies have defined CCS based on the normal population. The diagnosis is currently made based on clinical impression from radiographic studies. The aim of this study is to establish parameters that are associated with CCS, based on anatomic measurements on a large sample of skeletal specimens. METHODS: From the Hamann-Todd collection at the Cleveland Museum of Natural History, 1,066 skeletal specimens were selected. Digital calipers were used to measure the sagittal canal diameter (SCD), interpedicular distance (IPD), and pedicle length. Canal area at each level was calculated using a geometric formula. A standard distribution was created and values that were 2 SD below mean were considered as congenitally stenotic. An analysis of deviance was performed to identify parameters that were associated with CCS. Regression analysis was used to determine odds ratios (OR) for CCS using these parameters. RESULTS: CCS was defined at each level as: C3/4 = 1.82 cm(2), C4/5 = 1.80 cm(2), C5/6 = 1.84 cm(2), C6/7 = 1.89 cm(2), C7/T1 = 1.88 cm(2). Values of SCD < 13 mm and IPD < 22.5 mm were associated with CCS and yielded sensitivities and specificities of 88-100 % at each level. Logistic regression demonstrated a significant association between these parameters and presence of CCS with OR > 18 at each level. CONCLUSIONS: Based on our study of a large population of adult skeletal specimens, we have defined CCS at each level. Values of SCD < 13 mm and IPD < 23 mm are strongly associated with the presence of CCS at all levels.

Establishment of parameters for congenital thoracic stenosis: a study of 700 postmortem specimens.

BACKGROUND: Congenital thoracic stenosis (CTS) occurs when the bony anatomy of the canal is smaller than expected in the general population. The diagnosis currently is made based on the clinical impression from subjective radiographic studies, and the normal values for CTS have not been established. QUESTIONS/PURPOSES: We provided a statistical definition for CTS based on objective measurements of thoracic spine specimens and explored parameters that might predict CTS. METHODS: We selected 700 adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History (Cleveland, OH, USA). We used calipers to measure the sagittal canal diameter (SCD), interpedicle distance (IPD), and pedicle length (PL). At each level, canal area was calculated using a geometric formula, a standard distribution was created, and values two SDs below the mean were considered congenitally stenotic. Corresponding values of SCD and IPD of the stenotic specimens were studied. The values of SCD and IPD predicting CTS with highest sensitivity and specificity were tabulated. RESULTS: At each level, CTS was defined as: T1, 160 mm(2); T2, 135 mm(2); T3, 131 mm(2); T4, 130 mm(2), T5, 129 mm(2), T6, 127 mm(2); T7, 127 mm(2); T8, 129 mm(2); T9, 130 mm(2); T10, 132 mm(2); T11, 140 mm(2); and T12, 173 mm(2). A SCD less than 15 mm and an IPD less than 18.5 mm were predictive of CTS at each level with sensitivities and specificities of 80% to 100%. CONCLUSIONS: We statistically defined CTS at each level. A SCD less than 15 mm or IPD less than 18.5 mm predicted the presence of CTS at all levels. CLINICAL RELEVANCE: In a symptomatic patient, on routine radiologic examination, a physician should suspect stenosis of the thoracic canal if the SCD and IPD are less than 15 and 18.5 mm respectively. As a spinal deformity surgeon, the canal area is especially relevant when considering a possible canal intrusion by implants.

L5 pedicle length is increased in subjects with spondylolysis: an anatomic study of 1072 cadavers.

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.

Is congenital bony stenosis of the cervical spine associated with lumbar spine stenosis? An anatomical study of 1072 human cadaveric specimens.

OBJECT: Congenital cervical and lumbar stenosis occurs when the bony anatomy of the spinal canal is smaller than expected, predisposing an individual to symptomatic neural compression. While tandem stenosis is known to occur in 5%-25% of individuals, it is not known whether this relationship is due to an increased risk of degenerative disease in these individuals or whether this finding is due to the tandem presence of a congenitally small cervical and lumbar canal. The purpose of the present study was to determine if the presence of congenital cervical stenosis is associated with congenital lumbar stenosis. METHODS: One thousand seventy-two adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History were selected. The canal area at each level was calculated using a formula that was verified by computerized measurements. Values that were 2 standard deviations below the mean were considered to represent congenitally stenotic regions. Linear regression analysis was used to determine the association between the sum of canal areas at all levels in the cervical and lumbar spine. Logistic regression was used to calculate odds ratios for congenital stenosis in one area if congenital stenosis was present in the other. RESULTS: A positive association was found between the additive area of all cervical (that is, the sum of C3-7) and lumbar (that is, the sum of L1-5) levels (p < 0.01). A positive association was also found between the number of cervical and lumbar levels affected by congenital stenosis (p < 0.01). Logistic regression also demonstrated a significant association between congenital stenosis in the cervical and lumbar spine, with an odds ratio of 0.2 (p < 0.05). CONCLUSIONS: Based on the authors' findings in a large population of adult skeletal specimens, it appears that congenital stenosis of the cervical spine is associated with congenital stenosis of the lumbar spine. Thus, the presence of tandem stenosis appears to be, at least in part, related to the tandem presence of a congenitally small cervical and lumbar canal.