Intravoxel Incoherent Motion Factors Affecting Collapse and Nonunion of Osteoporotic Vertebral Fracture.

STUDY DESIGN: Longitudinal study. OBJECTIVES: Intravoxel incoherent motion (IVIM), a magnetic resonance imaging (MRI) scanning technique that applies diffusion-weighted imaging (DWI), is effective for the quantitative assessment of malignant tumors of the vertebral bone. We hypothesized that IVIM parameters of vertebral bodies are associated with the prognosis of osteoporotic vertebral fracture (OVF). We aimed to explore the relationships between IVIM parameters for vertebral collapse and non-union after OVF and calculate the cut-off values of these parameters for vertebral collapse and non-union. METHODS: A total of 150 patients with acute OVF (150 women; mean age: 79.1 ± 7.4 years) were included and treated conservatively with bracing. MRI was performed at the time of injury. IVIM parameters, such as apparent diffusion coefficient (ADC), molecular diffusion coefficient (D), and perfusion-related diffusion (D*) were recorded. The patients were classified into 3 groups: low-collapse (height loss of ≤50%), high-collapse (height loss of >50%), and non-union. We compared ADC, D, and D* among the low-collapse, high-collapse, and non-union groups and performed a receiver operating characteristic (ROC) curve analysis to determine the boundary values of the high-collapse and non-union groups. RESULTS: The low-collapse, high-collapse, and non-union groups had no significant differences in ADC and D. However, D* differed significantly among the 3 groups. ROC analysis revealed cut-off values of 19.0 × 10-3 mm2/s and 12.3 × 10-3 mm2/s for the high-collapse and non-union groups, respectively. CONCLUSIONS: D* is a significant prognostic indicator for high-collapse and non-union groups with OVF. This suggests that D* should be considered when assessing OVF.

Morphometry of the lumbar zygapophyseal facet capsule and cartilage with special reference to degenerative osteoarthritic changes: an anatomical study using fresh cadavers of elderly Japanese and Korean subjects.

Morphometric data were obtained from fresh cadaver dissections, and observations of degenerative changes in the joint cartilage (DCs) were analyzed to determine whether the morphometric parameters of the lumbar zygapophyseal joint capsule varied according to the presence and severity of DCs. There have been no previous morphometric studies of the facet capsule that describe age-related DCs. Using 23 fresh osteoligamentous lumbar spines from donated cadavers, we performed morphometric investigations of the surface areas of the joints and their capsules and measured the capsular thickness. We hypothesized that the ratio of the inner capsular area to the joint surface area for each facet (the capsule/facet index) could serve as an index showing a functional aspect of a large or small capsule. Our results showed that the joint surface area increased significantly with increasing severity of DCs, according to Grogan's classification. Facets with advanced DCs tended to have a small inner capsular surface. The capsule/facet index generally correlated positively with capsular thickness, especially the dorsal portion; however, this was not true for the ventral portion. The index also correlated negatively with DC progression. Thus, lumbar facet DCs were strongly linked to reconstructive alterations in capsular size, thickness, and looseness. The occurrence and progression of DCs narrowed the joint capsule, especially the dorsal portion, and this seemed to decrease the potential looseness of the joint. Conversely, these capsular alterations seemed to accelerate DC progression. A negative adaptation cycle seemed to occur.

Which portion in a facet is specifically affected by articular cartilage degeneration with aging in the human lumbar zygapophysial joint?

Using 10 osteoligamentous vertebral columns obtained from elderly donated cadavers, we describe in detail degenerative changes of the articular cartilage in lumbar zygapophysial joints to show which portion in a facet is specifically affected. Degenerative changes, including extended cartilage defects, occurred in multiple facets of every specimen. The results demonstrated 5 basic morphologies of degeneration, i.e., 1) marginal dominace in the articular surface, 2) lower segment dominance except for the lowest (L5/S) facet, 3) advancement in the inferior articular process, 4) cranial and caudal dominance rather than the dorsal dominance in the articular surface and 5) progress in a mirror-image manner. These rules seemed to be consistent with differences in size, shape and kinesiological aspects of the facet between segments and between portions in a facet.

Morphometrical study of the joint surface and capsule of the lumbar zygapophysial joint with special reference to their laterality.

Using 26 osteoligamentous lumbar vertebral columns (260 facets), we morphometrically investigated the cartilagenous joint surface, inner capsular surface and capsular thickness. We also examined whether the subcapsular pocket was present and, if present, how far it extended along the joint margin. The proportion of the inner capsular area in the total joint surface area in a facet (the capsular-joint surface ratio) was hypothesized to correspond to the potential looseness (or tightness) of the facet. The absolute data themselves seemed to be useful for better understanding of the joint morphology. However, further evaluations of the differences between segments, left/right differences, individual segmental fluctuation patterns and correlations between parameters provided a novel classification of specimens according to the hypothetical progress of joint degeneration. Criteria for the classification existed in 1) the laterality in parameters defined as more than 100% larger or smaller than the contralateral facet and 2) the drastic segmental difference in parameters over 50% larger or smaller than the adjacent segment. Consequently, three types were identified: 1) outside of the criteria in both area and thickness (-/- type, 9 of 26); 2) the criteria did not fit the area parameters but did fit the thickness parameters (-/+ type, 8); the criteria were filled in both categories of parameters (+/+ type, 9). Notably, in the +/+ types, the capsular thickness and capsular-joint surface ratio correlated significantly (p < 0.01), i.e., the hypothetical loose joint had a thick capsule. We speculated that early joint degeneration starts from the -/- type and advances via the -/+ type to the +/+ type. Considerating these results, we recommended using MR imaging for detailed identification of laterality in the capsular thickness for low-back pain patients to discriminate candidates for future severe degenerative changes of the articular cartilage in the lumbar spine.