Lumbar vertebrae architecture and spondylolysis

Lumbar isthmic spondylolysis (ISP) is a defect in the pars interarticularis separating the vertebral arch into ventral and dorsal parts, either unilaterally or bilaterally. Strong heredity, repeated trauma and stress, and lumbar hyperlordosis are suggested as possible causative factors. While many studies have explored the relationship between facet architecture (in particularly facet orientation and tropism) and degenerative spondylolisthesis, there is a dearth of knowledge regarding the relationship with ISP. Ward and Latimer demonstrated that normal individuals have a significantly greater increase in interfacet dimensions progressing down the spine from L4 to S1 than those with ISP. Grobler et al reported that individuals with ISP manifest reduced transverse articular dimension.
The aim of our research was to characterize the relationship between articular facet orientations and isthmic spondylolysis in the lumbar spine. Excessive frontal orientation and tropism of the lower lumbar facets were found to be strongly associated with isthmic spondylolysis.

Lumbar vertebral facet and interfacet size and shape in spondylolysis
Opinions differ as to the exact mechanism responsible for spondylolysis (SP) and whether individuals with specific morphological characteristics of the lumbar vertebral neural arch are predisposed to SP. The aim of our study was to reveal the association between SP and the architecture of lumbar articular facets and the interfacet region. Three profound differences between SP and the norm appear: the first relates to the size and shape of the neural arch of L4, with significantly greater interfacet widths; significantly shorter interfacet heights; and significantly shorter and narrower articular facets. The second refers to the condition where only in L4 was the inferior interfacet width similar in size to the superior interfacet width of the vertebra below (L5). The third relates to the fact that in all lumbar vertebrae the right inferior articular facets in SP were flatter than the norm. Conclusions: Individuals with L4 "SP" characteristics are at a greater risk of developing fatigue fractures in the shape of isthmic lysis at L5.

Bone asymmetry of the neural arch in the thoraco-lumbar spine

The ontogeny of the human vertebra is of the most complicated in the human body. One aspect of this vertebral complexity is the shape of its neural arch due to its numerous anatomical parts. This was further complicated by the existence of asymmetry in the neural arch. The exact amount and location of this asymmetry in the normal spine is yet to be thoroughly investigated. Most studies were interested mainly in the pedicles, as it is a major location of surgical procedures. Yet, it is impossible to understand all aspects of this asymmetry based on isolated anatomical parameters of typical vertebrae. Recent studies on facet morphology have presented a clear pattern of unilateral asymmetry along the thoracic and lumbar spine. Further exploring the major characteristics of asymmetry in the neural arch may have certain applications: it may greatly facilitate the diagnosis of pathological conditions in the spine, offer new insight into surgical procedures of the spine, and furnish spinal therapists with crucial data as to accurate manipulation of the spine.
This study aims to use direct measurements to characterize the incidence and location of any normal asymmetry in major parts of the neural arch along the thoracic and lumbar vertebrae by gender, age and ethnicity.

Age-Related Changes in the Cross Sectional Area (CSA) of the Posterior Abdominal Muscles (Psoas Major, Multifidus, Erector Spinae): A CT Study

Sarcopenia typifies changes in muscle mass due to aging. It is generally agreed that total muscle mass decreases by nearly 50% between the ages of 30 to 90. Computed tomography (CT) of lower limb muscles demonstrate that after age 30, cross-sectional muscle areas decrease by 15% per decade, with decreased muscle density associated with increased intramuscular fat. These changes are more pronounced in women. The reduction of muscle mass in upper and lower limbs is mainly due to selective atrophy of type II muscle fibers.
Age-related reduction in muscle mass is linked with alteration in muscle biochemistry, muscle physiology (e.g., decrease in strength, power, and endurance), muscle morphology (e.g., changes in size, contour and number) and functional disability. It is also associated with increased fatigue, pain and reduced function. Yet, the tempo and mode of age-related muscle mass reduction varies largely among individuals (due to genetic, environmental conditions, social customs and nutritional habit) and various muscles.
The purpose of the current research is to follow age-related changes in the cross sectional area (CSA) of two types of muscles in the posterior abdominal wall: extrinsic [psoas major (PM)], and intrinsic [multifidus (MF) and erector spinae (ES)]. Our results clearly show that for all three muscles, mass reduction begins as early as the fourth decade of life, continuing to decrease at an average rate of ca 1% per annum, exception being PM in women, exhibiting a much lower decreasing rate (0.5%/per annum). No correlation was found between the CSA of the muscles and body mass index.

Sacral Inclination: Its Association with Scheuermann’s Kyphosis and Idiopathic Scoliosis

A descriptive skeletal study of the association between sacral inclination (SI) angle and spinal deformities was carried out in order to determine whether sacral inclination (SI) is a contributing factor in the development of Scheuermann’s kyphosis (SK), idiopathic scoliosis (IS) and Scheuermann’s kyphoscoliosis (KS). SI angle was measured in 194 skeletonized pelves of individuals with normal spines, 112 with SK, 36 with IS, and 71 with KS. Kyphosis was diagnosed when 3 adjacent vertebrae were anteriorly wedged more than 5° degrees. Scoliosis was diagnosed when 3 adjacent vertebrae were laterally wedged more than 3°. In the Caucasian population a clear association (p<0.001) was found between SI angle and spinal deformities (SK and IS). SI angle was 54.9°±7.3° in normal spines, 46.6°±8.8° in kyphotic/scoliotic spines and 40.8°±7.7° in kyphoscoliotic individuals. In African-Americans, SI angle was only kyphosis dependent: 48.9°±9.6° in normal spines vs. 42.7°±7.4° in kyphotic spines. We therefore concluded that a horizontally oriented sacrum may be involved in the development of spinal deformities (especially kyphosis).

The elusive “Sacral Inclination”: Its demographic nature and association with spinal deformities

This study was carried out in order to reveal the association between sacral inclination (SI), demographic parameters and spinal deformities (kyphosis and scoliosis). 411 pelves of individuals of various age, sex and race were studied. SI is measured as the angle created between a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior corner of the symphysis pubis. Kyphosis is defined as 3 adjacent vertebrae wedged more than 5º each and an overall kyphosis of at least 21º (T4-T9). Scoliosis was defined as 3 adjacent vertebrae wedged more than 3º each.
SI was found to be race dependent [(41.16º±9.5 in blacks vs. 35.08º±7.35 in whites (p<0.001)] and sex independent. There is a 10º change in inclination from age 20 to 50 years. SI was spinal deformity dependent in the White population (p<0.001): 35.08º±7.35 in normal spine; 43.73º±9.96 in deformed spine (kyphosis/scoliosis); and 48.52±7.33 in kyphoscoliosis spine.
In conclusion, unlike the common notion, SI does not contribute significantly to the female's birth canal. The sacrum is more horizontally oriented in Blacks, which in turn may explain the difference in lumbar lordosis between blacks and whites. The sacrum becomes more horizontally oriented with age, this may contribute to reduce stabilization of the lumbo-sacaral junction with age and appearance of pathologies such as spondylolystesis. Finally, SI is a clear risk factor for the development of spinal deformities.

Sacroiliac joint ankylosing: From evolution to paleopathology

The sacroiliac joint's structure, movement and load handling are unique in relation to other joints in the body. Ankylosing of the sacroiliac joints (SIA) has been observed and reported in both the medical and anthropological literature. Nevertheless, contradictory results as to the true nature of the phenomenon exist. As the area has significant implication to both the field of paleopathology (spondyloarthropathy, DISH etc.) paleodemography (mainly aging technique) and evolution (bipedal locomotion), we set a project to define the phenomenon demographically and morphologically and shed light on its etiology. The study was conducted on 2845 skeletons from the Hamann-Todd collection CMNH. 10.5% of all individuals examined showed evidence of SIA. The phenomenon is either bi or unilateral (no side preference) and occurs mainly on the superior aspect of the joint surface. The bony bridge always develops from the ilium towards the sacrum. It is sex (12.3% in males and 1.8% in females) and age (r=0.985) dependent and race and size independent. SIA is usually accompanied by other changes in the skeleton, although no direct relationship with DISH or spondyloarthropathy was found. Only slight changes were noticed in the cartilage of the joints with ankylosing (and therefore cannot be the trigger to the process). The study discusses the implication of the findings to paleopathology, evolution of bipedal locomotion (and erect posture) and aging methods.

Pelvis architecture and Urinary Incontinence in women

Objective: To examine anatomical features in the pelvic bones and muscles in women with urinary incontinence (UI).
Material and methods: Between October 2005 and January 2006, 212 women underwent pelvic computerized tomography in our center. Preceding the examination, all women completed a clinical and demographical questionnaire including detailed questions about UI. Several anatomical parameters using multi-planar reformation and 3-dimensional techniques (volume rendering) were examined. We specifically evaluated different bony parameters, pelvic floor muscles angles, densities and cross sectional areas. 46.5% had UI and the reminder served as the control group. A logistic regression-model was used to evaluate risk factors for UI.
Results: The mean age was 55.5 years (range 19-90). Women who suffered from UI were older (60.97 vs. 50.77 years, p<0.0001), with higher body mass index (27.65 vs. 25.49, p<0.01), had more previous hysterectomies (21.5% vs. 6.5%, p<0.005), underwent more pelvic irradiation (9.7% vs. 1.8%, p<0.05) and had more diabetes mellitus (31.2% vs. 13.1%, p<0.005). Patient's age and previous hysterectomy were found to be the major clinical risk factors for UI (OR 1.029, p=0.002; OR 2.94, p=0.024, respectively). Logistic regression analysis on all clinical and morphological variables yielded the following risk factors: pelvic-inlet diameter (OR 1.216, p<0.0001), pelvic-inlet AP diameter (OR 1.109, p=0.003), pelvic-outlet diameter (OR 1.077, p=0.011) and transverse perineal muscle cross section diameter (OR 0.773, p<0.0001).
Conclusions: Pelvic inlet and outlet dimensions are major risk factors for developing UI in women. These findings may lead to a better comprehension of the pathophysiology of UI in women.

Sacroiliac joint bridging: simple and reliable criterion for determining skeleton gender

Determination of skeleton gender is vital to the study of past populations and an important phase in executing a forensic anthropological examination. The aim of this study is to present an easy and reliable criterion for determining skeleton gender.
The ilium and sacrum of 2,845 skeletons were examined for new bone formation and bridging/fusion in/across the sacroiliac joint. Sacroiliac joint bridging (SIB) was present in 12.27% of the males (age 18 to 105 years) and 1.83% of the females. In 97% of the males the bridging was extra articular while in all females the bridging was intra articular. SIB was also found to be ethnic origin independent and age dependent.
Bony spurs present on the ilium for a preliminary, partial or full extra-articular bridging of the sacroiliac joint, testify for male skeleton. SIB presents an easy methodology for sexing the skeletons (especially of old individuals when the phenomenon become very common and where traditional methods become less reliable), as no prior knowledge, training, or equipment is required to apply the criterion.

A descriptive study of the association between sacroiliac joint bridging (SIB) and age, gender, laterality and ethnic origin in a normal skeletal population. The effectiveness of x-rays in identifying SIB was also evaluated.
The major objectives were to characterize the phenomenon of SIB demographically and anatomically and to evaluate the validity of diagnosis based on roentgenograms.
Although SIB is an important diagnostic parameter in many spinal diseases, the type of association between them has never been established. Furthermore, the extent of SIB in humans and its relationship to demographic parameters await osteological research as X-rays studies hamper the results. 2845 skeleton pelvises were examined for SIB. Extent and laterality were recorded. Ten pelvises (5 with SIB and 5 without) were x-rayed and the roentgenograms given to radiologists for evaluation.
Sacroiliac bridging was present in 12.27% of all males, contrasted with only 1.83% of females (p<0.001). SIB was independent of ethnic origin (p=0.0535), but was age-dependent (r =0.985; P=0.0001). Bridging was present bilaterally in 38.6% of the individuals and in the superior region in 72.4%. Diffuse bridging (areas 1-6) was present in only 2.3% of the individuals. Radiological examination was insensitive to diagnosis of SIB. In conclusion, SIB is a common, but predominantly male phenomenon. Its occurrence is age dependent and ethnicity independent. Bridging occurs mainly on the superior aspect of the sacroiliac joint. The irregular shape and orientation of sacroiliac joints preclude definitely distinguishing normal versus bridged joints from roentgenograms. Our findings also negate the belief that bridging/fusion of the sacroiliac joint represents the most severe form of osteoarthritis and mandate that they be separately recorded, and their significance determined.

Although the spinal motion segment has received considerable attention, the nature of one of its component, the “epiphyseal” ring remained obscure. In most medical discussions, the term “end-plate” refers only to be the thin layer of hyaline cartilage that lies between the bone of the vertebral body and the soft tissue of the disc, it does not include the ring! (Moore 2000). Although most researchers agree as to its main function (anchoring the fibers of the annulus fibrosus), its unique characteristic in humans has never been studied. The hot debate in the early 20th century, following the inference made by Schmorl and Junghanns (1932), who called the ring “Randlciste”, and Beadle (1931), who argued that the epiphyseal ring is a separate entity from the cartilagineous plate and serves a different function, has long evaporated, with the issue, however, remaining unsettled. Beadle (1931) strongly argued that the epiphyseal ring is not concerned with growth (as there is no evidence of endochondral growth at the epiphysis, as there is at the base of the cartilaginous plate). He stated that the epiphysis simply grows within itself until it occupies the cartilaginous ring, then fuses to the underlying bone.