Toshiki Abe

Histomorphometric evaluation of the effects of ovariectomy on bone turnover in rat caudal vertebrae.

Abstract. The purpose of this study was to learn whether caudal vertebrae can be used to evaluate the effects of ovariectomy (OVX) in rats. Seven-month-old female Wistar rats were divided into two groups: the OVX group and the untreated control group. All rats were killed at 8 weeks and their 4th lumbar (L4), 1st caudal (C1), 3rd caudal (C3), and 5th caudal (C5) vertebrae were processed undecalcified and sectioned with Villanueva bone stain for quantitative bone histomorphometry. Both length of vertebral bodies and the cancellous tissue area in C1 were similar in size to L4 but significantly bigger than C3 and C5. Within the groups, cancellous bone volume (BV/TV) and trabecular thickness in both groups gradually increased in caudal vertebrae in relation to the distal direction. Between the groups, OVX rats exhibited a significantly lower BV/TV relative to control rats at L4 and C1, however, no significant difference were seen at C3 and C5. Bone formation-related parameters such as osteoid and mineralizing surface, and eroded surface were higher in the OVX group than in the control group in caudal as well as in lumbar vertebrae. By quantitative analysis of bone marrow composition, yellow marrow volume in C3 and C5 was significantly higher than that in L4 and C1, in both groups. Our results suggest that C1 is similar to L4 in size, bone turnover, and bone marrow composition. However, further experiments are needed to evaluate the possibility that C1 vertebra could be used as an alternative site for histomorphometric evaluation of bone changes in OVX rats.

Trabecular remodeling processes in the ovariectomized rat: modified node-strut analysis

The purpose of this study was to evaluate the trabecular bone remodeling processes in ovariectomized rats, focusing on diminishing trabecular connectivity. We used modified node-strut analysis defining three areas in the trabecular surfaces for the three-dimensional understanding of trabecular resorption derived from two-dimensional conventional sections, in addition to conventional bone histomorphometry and node-strut analysis. Seven-month-old female Wistar rats were used and treated with bilateral ovariectomy (ovx) and sham operation. Six rats in each group were examined at 4 and 8 weeks. We prepared undecalcified sections from the left tibiae with Villanueva bone and Goldner stains. We divided the trabecular bone surfaces (BS) into three areas: node (Nd), terminus (Tm), and strut (St), and measured the bone resorption and formation parameters, including eroded surface (ES), osteoclast surface (Oc.S), osteoid surface (OS), and double-labeled surface (dLS) in each defined area. In conventional bone histomorphometry, the ovx group showed high turnover osteopenia compared with the sham operation group. In node-strut analysis, the ovx group showed significantly lower values for node-related parameters than did the sham operation group. In the modified node-strut analysis, bone resorption parameters in the ovx group showed significantly higher values, particularly for strut and terminus-eroded surfaces (StES/BS, TmES/BS), and for each area of osteoclast surface (NdOc.S/BS, TmOc.S/BS, and StOc.S/BS) compared with the sham operation group. Bone formation parameters in the ovx group also showed significantly higher values, particularly for strut and terminus osteoid surfaces (TmOS/BS, StOS/BS), and for each area of double-labeled surface (NddLS/BS, TmdLS/BS, and StdLS/BS) compared with the sham operation group at 4 weeks. At 8 weeks, each area of bone formation parameter in the ovx group showed significantly higher values than that in the sham operation group. These results suggest that in the ovx group, the trabecular plates became perforated and the perforative cavities progressively enlarged, and/or the edges of plates were eroded regardless of elevated bone formation, resulting in diminished trabecular connectivity, and the node area might not be influenced relatively by bone remodeling in the early resorption.

Long-Term Effects of Withdrawal of Bisphosphonate Incadronate Disodium (YM175) on Bone Mineral Density, Mass, Structure, and Turnover in the Lumbar Vertebrae of Ovariectomized Rats†

This study was designed to evaluate the long‐term effects of incadronate disodium (YM175) after its withdrawal on cancellous bone mass in ovariectomized (OVX) rats. Thirteen‐week‐old female SD rats were randomized into four groups: sham‐operated, OVX, low‐YM, and high‐YM (0.01 mg/kg or 0.1 mg/kg subcutaneously [sc], three times a week after OVX) groups. After 4 weeks of treatment with vehicle or YM175, rats from each group were killed at time points of 0 (baseline), 3, 6, 9, and 12 months after withdrawal of the agent. Bone mineral density (BMD) of the lumbar vertebrae was measured by dual‐energy X‐ray absorptiometry (DXA). Bone volume (BV/TV), trabecular number and trabecular separation (Tb.N and Tb.Sp), eroded surface (ES/BS), osteoclast number and osteoclast surface (N.Oc/BS and Oc.S/BS), osteoid surface (OS/BS), and bone formation rate (BFR/BS) were measured as histomorphometric parameters of the fifth lumbar vertebra. BMD, BV/TV, Tb.N, and Tb.Sp in YM175‐treated groups were maintained at the same level as in the sham group until 12 months after withdrawal in the high‐YM group and until 3 months after withdrawal in the low‐YM group. YM175 decreased both bone formative and resorptive parameters in histomorphometry. Serum bone‐specific alkaline phosphatase (ALP) and urinary deoxypyridinoline at both doses of YM175 also showed a suppressive effect of this agent on bone turnover. These results indicate that YM175, after withdrawal, still maintains bone volume dose dependently by depressing bone resorption and formation in OVX rats. Intermittent YM175 treatment with a long interval may be sufficient to maintain the bone volume and structure in OVX rats.

Anterior decompression for far-out syndrome below a transitional vertebra: a report of two cases

BACKGROUND CONTEXT Impingement of the L5 nerve between the transverse process of L5 and the ala of sacrum has been described as the far-out syndrome. Posterior decompression is often performed for this pathology. PURPOSE To describe rare cases of far-out syndrome below a transitional vertebra who underwent anterior decompression. STUDY DESIGN/SETTING A case report and a review of the literature. METHODS Review of the hospital medical record, history, physical examination, and imaging studies. RESULTS A 70-year-old woman and a 53-year-old man presented with prolonged and progressive leg pain and/or low back pain. Both of the patients showed muscle weakness and sensory disturbance at L5 level and lumbosacral transitional vertebra on the plain radiography. Magnetic resonance imaging showed huge osteophytes, and there was severe impingement of the L5 nerve at the anterior exit zone of the foramen. Anterior decompression was performed for both cases using a Fraser incision and resulted in successful resolution of the symptom and neurological status. CONCLUSION In the extraforaminal stenosis of the L5 nerve with far-out syndrome below the transitional vertebra, entrapment occurs more anterior of exit zone of the L5 nerve foramen than in the other pathologies; anterior decompression brings in more complete decompression.

Posterior-approach vertebral replacement with rectangular parallelepiped cages (PAVREC) for the treatment of osteoporotic vertebral collapse with neurological deficits.

Study Design: A retrospective clinical study. Objective: To assess the efficacy of a new spinal reconstruction technique (posterior-approach vertebral replacement with rectangular parallelepiped cages: PAVREC) for the treatment of osteoporotic late vertebral collapse with neurological deficits. Summary of Background Data: Poor bone quality and medically complicated situations obfuscate precise treatment for paraplegia caused by osteoporotic vertebral collapse. Recently, posterior-approach corpectomy and replacement with a cylindrical cage have been proposed. However, postoperative cage subsidence and kyphosis progression frequently occurs. Methods: Surgical invasiveness, perioperative complications, and clinical and radiographic outcomes in a total of 19 consecutive patients with osteoporosis (7 men and 12 women; mean age, 75 y) who underwent PAVREC with a mean follow-up period of 45.6 months (range, 16–79 mo) were reviewed. The affected vertebral levels ranged from T12–L4. The mean bone mineral density of the femoral neck was 0.611±0.077 g/cm2 (mean±SD). Results: Mean operative time was 261 minutes (range, 155–326 min). Mean blood loss was 664 mL (range, 197–1595 mL). There were no reported surgical complications. Neurological deficits evaluated with the Frankel grading score improved >1 grade after surgery in all patients. Mean preoperative visual analog scale scores for back or leg pain (7.2; range, 6–9) significantly improved after surgery (1.4; range, 0–2) (P<0.05). Local kyphosis improved from a mean of 24.6 degrees before surgery to a mean of 1.5 degrees after surgery (P<0.05), and it was maintained at a mean of 2.5 degrees at the final follow-up. Although screw loosening, cage subsidence, and subsequent vertebral fracture were seen in several cases, no additional surgeries were needed. Solid bony fusion was confirmed in all cases. Conclusions: PAVREC provided a satisfactory clinical and radiologic outcome without severe complications. This procedure can be a treatment option for osteoporotic vertebral collapse and an alternative to an anterior-approach or single posterior-approach reconstruction with a cylindrical cage.

Anterior Decompression and Shortening Reconstruction with a Titanium Mesh Cage through a Posterior Approach Alone for the Treatment of Lumbar Burst Fractures

Study Design A retrospective study. Purpose To examine the efficacy and safety for a posterior-approach circumferential decompression and shortening reconstruction with a titanium mesh cage for lumbar burst fractures. Overview of Literature Surgical decompression and reconstruction for severely unstable lumbar burst fractures requires an anterior or combined anteroposterior approach. Furthermore, anterior instrumentation for the lower lumbar is restricted through the presence of major vessels. Methods Three patients with an L1 burst fracture, one with an L3 and three with an L4 (5 men, 2 women; mean age, 65.0 years) who underwent circumferential decompression and shortening reconstruction with a titanium mesh cage through a posterior approach alone and a 4-year follow-up were evaluated regarding the clinical and radiological course. Results Mean operative time was 277 minutes. Mean blood loss was 471 ml. In 6 patients, the Frankel score improved more than one grade after surgery, and the remaining patient was at Frankel E both before and after surgery. Mean preoperative visual analogue scale was 7.0, improving to 0.7 postoperatively. Local kyphosis improved from 15.7° before surgery to -11.0° after surgery. In 3 cases regarding the mid to lower lumbar patients, local kyphosis increased more than 10° by 3 months following surgery, due to subsidence of the cages. One patient developed severe tilting and subsidence of the cage, requiring additional surgery. Conclusions The results concerning this small series suggest the feasibility, efficacy, and safety of this treatment for unstable lumbar burst fractures. This technique from a posterior approach alone offers several advantages over traditional anterior or combined anteroposterior approaches.

Bone-loss pattern of corticosteroid-induced osteopenia in rats: A node-strut analysis of the tibia

The purpose of this study was to determine how corticosteroid-induced osteopenia in rats develops by using conventional bone histomorphometry and node-strut analysis. Seven-month-old female Wistar rats were divided into three groups: an untreated control group, a low corticosteroid dose group (prednisolone, 2.5 mg kg−1 day−1), and a high corticosteroid dose group (prednisolone, 12,5 mg kg−1 day−1). Prednisolone was administered six times each week for 4 and 8 weeks. At necropsy, the left tibiae were collected, and sections were prepared using Villanuevas bone stain. Histomorphometrically, corticosteroid at both doses reduced the trabecular thickness at the 4th week, and significant bone loss was established at the 8th week with strong suppression of bone formation. In node-strut analysis, neither node-related nor terminus-related parameters changed significantly in any group at either treatment duration. These results indirectly suggest that trabecular thickness is reduced but the trabecular network is preserved in corticosteroid-induced osteopenia in rats.

Fusion of Multiple Segments Can Increase the Incidence of Sacroiliac Joint Pain After Lumbar or Lumbosacral Fusion.

Study Design. A retrospective study. Objective. To determine the risk factors for sacroiliac joint pain (SIJP) after lumbar or lumbosacral fusion. Summary of Background Data. Recently, the sacroiliac joint has gained increased attention as a source of pain after lumbar or lumbosacral fusion. We examined the factors related to the development of SIJP after lumbar or lumbosacral fusion. Methods. In total, 262 patients who underwent lumbar or lumbosacral fusion from June 2006 to June 2009 were included in this study. All patients who did not show SIJP clinically in the preoperative screening period were considered. Of these patients, 28 newly developed SIJP. We investigated whether development of SIJP after lumbar or lumbosacral fusion is related to the presence of fusion involving the sacrum (floating fusion vs. fixed fusion) and the number of fused segments. Results. The incidence of SIJP was higher with fixed fusion (13.1%) than with floating fusion (10.0%). With regard to the number of fused segments, the incidence of SIJP was 5.8% for one fused segment, 10.0% for two segments, 20.0% for three segments, 22.5% for at least four segments. Thus, the incidence was significantly higher when at least three segments were fused. Logistic regression analysis was performed to determine if the development of SIJP was related to the presence of fusion involving the sacrum or the number of fused segments. The analysis revealed that the number of fused segments was significantly associated with the development of SIJP. Conclusion. SIJP is a potential cause of low back pain after lumbar or lumbosacral fusion surgeries. Our study indicated that fusion of multiple segments (at least three) can increase the incidence of SIJP after lumbar or lumbosacral fusion. Level of Evidence: Level 3

Remote cerebellar hemorrhage following thoracic spinal surgery of an intradural extramedullary tumor: a case report

IntroductionRemote cerebellar hemorrhage is a rare complication of spinal surgery. Although loss of cerebrospinal fluid seems to play an important role in the pathogenesis of this complication, the detailed mechanism of remote cerebellar hemorrhage after spinal surgery remains unclear. We report the case of a patient with remote cerebellar hemorrhage following thoracic spinal surgery of an intradural extramedullary tumor and discuss this entity with reference to the literature.Case presentationA 57-year-old Japanese woman presented to our hospital with back pain, dysuria, and numbness of both legs. A neurological examination was performed, and imaging was performed with ordinary radiography, magnetic resonance imaging, and computed tomography. Her magnetic resonance imaging scan showed an intradural extramedullary tumor at the T3 level. A tumor resection and T1-T5 pedicle screw fixation were performed. Twelve hours after spinal surgery, she complained of unexpected dizziness, nausea, and vomiting. A total of 850mL of serosanguineous fluid had been drained at that time, and drainage was stopped. An urgent brain computed tomography scan showed a cerebellar hemorrhage. She was treated conservatively, and was able to leave hospital six weeks after the initial operation, without any neurological deficits except for slight ataxia.ConclusionsRemote cerebellar hemorrhage has to be suspected when unexpected neurological signs occur after spinal surgery. If an excessive amount of cerebrospinal fluid drains from the drainage tube after spinal surgery, drainage should be stopped.

Gossypiboma 19 years after laminectomy mimicking a malignant spinal tumour: a case report

IntroductionGossypiboma is rare and mostly asymptomatic in chronic cases. It can be confused with other soft tissue masses.Case presentationOur patient was an 87-year-old Japanese man with a history of surgery for a lumbar lesion causing lumbar canal stenosis 19 years earlier. Computed tomography showed a soft tissue mass with osteolysis and periosteal thickening of the vertebral lamina. On magnetic resonance imaging, the mass showed heterogeneous signal intensity on T2-weighted imaging, suggesting a malignancy. At the time of biopsy, small pieces of retained surgical sponge were collected. Surgical treatment was performed to excise the soft tissue tumour.ConclusionsGossypiboma should be included in the differential diagnosis of soft tissue masses in the paraspinal region in patients with a history of previous spinal surgery.