Estrogen deficiency accelerates lumbar facet joints arthritis.

Dramatic increase in the prevalence of lumbar facet joint (LFJ) arthritis in women around the age of menopause indicates a protective role for estrogen in LFJ arthritis. To date, there is no evidence for this indication and the mechanism of such an effect remains poorly understood. In this study, ovariectomized (OVX) mice were used to mimic the estrogen-deficient status of post-menopausal women. Micro-CT and immunohistochemistry was employed to assess the morphological and molecular changes in ovariectomy-induced LFJ arthritis. The results show that the LFJ subchondral bone mass was significantly decreased in OVX mice, with increased cavities on the interface of the subchondral bone. Severe cartilage degradation was observed in ovariectomy-induced LFJ arthritis. Increased blood vessels and innervations were also found in degenerated LFJ, particularly in the subchondral bone area. 17ß-Estradiol treatment efficiently suppressed LFJ subchondral bone turnover, markedly inhibited cartilage degradation, and increased blood vessel and nerve ending growth in degenerated LFJ in OVX mice. Our study reveals that estrogen is a key factor in regulating LFJ metabolism. Severe LFJ degeneration occurs when estrogen is absent in vivo. Collapsed subchondral bone may be the initiation of this process, and estrogen replacement therapy can effectively prevent degeneration of LFJ under estrogen-deficient conditions.

Characterization of subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis.

Facet joint osteoarthritis may be a cause of low back pain in degenerative spine diseases including lumbar spinal stenosis. Subchondral bone is regarded as a potential therapeutic target for osteoarthritis treatment. The goal of this study was to characterize subchondral bone histopathology in osteoarthritic facet joints from lumbar spinal stenosis patients. Fifteen patients with degenerative spinal stenosis scheduled for transforaminal lumbar interbody fusion surgery were recruited for this study. Osteoarthritis severity was graded on T1- and T2-weighted MRI images using Weishaupt scoring system. Dissected osteoarthritic facet joints were subjected to histological and immunohistochemistry analyses to study relative abundance of osteoblast, osteoclasts, and macrophages using van Gieson's, tartrate-resistant acid phosphatase and CD68-antibody staining, respectively. Presence of nerve fibers was evaluated by PGP9.5-antibody staining. Differential bone histopathology, independent from radiological osteoarthritis grade, was observed in facet joints. Extensive de novo bone formation was found in subchondral bone tissues of eight of fifteen specimens. Regions of bone formation showed high abundance of blood vessels and CD68-positive macrophages, but were devoid of multinucleated osteoclasts. Additional pathological changes in subchondral marrow spaces, including inflammatory infiltration and enhanced osteoclast activity, were characterized by macrophage-rich tissues. PGP9.5-positive nerve fibers were detected near arterioles, but not in regions displaying bone pathology. Individual histopathological parameters did not associate with clinical features or radiological osteoarthritis severity. Subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis is characterized by marrow infiltration by macrophage-rich tissues and enhanced de novo bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1475-1480, 2016.

Anatomic features of the paramedian muscle-splitting approaches to the lumbar spine.

BACKGROUND: Intermuscular approaches can expose the lumbar spine and minimize muscular trauma and injury. The segmental anatomy of the posterior lumbar musculature allows surgical access through separation of muscle groups and fascicles and provides one to develop intermuscular working channels while preserving the integrity of the muscles and their function. In addition, preservation of the accompanying neurovascular bundles minimizes blood loss, tissue atrophy, and pain. With these approaches, a variety of procedures for decompression, discectomy, interbody fusion, or pedicle screw fixation can be achieved for single or multiple levels without subperiosteal stripping or muscle transection. OBJECTIVE: A detailed description of the relevant surgical anatomy for the muscle-sparing approach to the lumbar spine.

Spontaneous hemorrhage into a lumbar synovial cyst.

Lumbar synovial cysts frequently present with back pain, chronic radiculopathy and/or progressive symptoms of spinal canal compromise. These cysts generally appear in the context of degenerative lumbar spinal disease. Few cases of spontaneous hemorrhage into synovial cysts have been reported in the literature.

Correlation of histopathological findings and magnetic resonance imaging in the spine of patients with ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease which affects primarily the sacroiliac joints and the spine. In patients with active disease, magnetic resonance imaging (MRI) of the spine shows areas of bone marrow edema, the histopathological equivalent of which is unknown. In this study we correlate inflammation in the spine of patients with AS as revealed by histological examination with bone marrow edema as detected by MRI. We have compared the histopathological findings of zygapophyseal joints from 8 patients with AS (age: 30 to 64, disease duration 7 to 33 years) undergoing spinal surgery with findings in MRI. For histopathological analysis, we quantified infiltrates of CD3+, CD4+ and CD8+ T cells as well as CD20+ B cells immunohistochemically. Bone marrow edema was evaluated in hematoxylin and eosin stained sections and quantified as the percentage of the bone marrow area involved. All patients with AS showed interstitial mononuclear cell infiltrates and various degrees of bone marrow edema (range from 10% to 60%) in histopathological analysis. However, in only three of eight patients histopathological inflammation and edema in the zygapophyseal joints correlated with bone marrow edema in zygapophyseal joints of the lumbar spine as detected by MRI. Interestingly, two of these patients showed the highest histological score for bone marrow edema (60%). This first study correlating histopathological changes in the spine of patients with AS with findings in MRI scans suggests that a substantial degree of bone marrow inflammation and edema is necessary to be detected by MRI.

Symptomatic hematoma of lumbar facet joint: joint apoplexy of the spine?

STUDY DESIGN: A case report. OBJECTIVES: To report and discuss a rare case of epidural hematoma that was considered to be formed as a result of idiopathic bleeding occurring at the facet joint (joint apoplexy). SUMMARY OF THE BACKGROUND DATA: Spontaneous spinal epidural hematoma is a relatively rare condition. According to a review article of 199 spontaneous spinal epidural hematomas in the last 2 decades, the majority of these conditions are thought to result from a rupture of the epidural vascular network. Recently, a hemorrhagic lumbar synovial cyst and a hematoma occurring from the ligamentum flavum were reported as rare types of epidural hematoma. METHODS: The authors describe the treatment and the clinical, radiologic, surgical, and pathologic findings in one patient with a rare epidural hematoma. RESULTS: Magnetic resonance imaging revealed that the extradural mass lesion was continuous with the right L4-5 facet joint; this was confirmed by surgery when the extradural hematoma was directly visualized. The joint cavity was also filled with the hematoma. There was no evidence of preceding cyst formation macroscopically or microscopically. The excised capsule of the left L4-5 facet joint revealed moderate hyperplasia of the synovium with an increased number of capillary vessels. CONCLUSIONS: This is the first reported case of radiculopathy considered to be a result of facet joint apoplexy in the absence of any preceding synovial cyst formation. The pathomechanism of the hemorrhage at the lumbar facet joint is unclear, but it is speculated that there could be an association with degenerative change of the facet joint. Surgical excision of this mass was considered to be the definitive treatment.