Anatomical Evaluation of Lumbar Arteries for Lateral Lumbar Interbody Fusion with Magnetic Resonance Imaging.

INTRODUCTION: Lateral lumbar interbody fusion (LLIF) is becoming a more common surgical treatment option for adult degenerative lumbar conditions. LLIF is a mini-open access technique with wound retractors, and postoperative hematoma due to segmental vessels injury is reported. Thus, it is considered that there is a need to conduct detailed preoperative examinations to identify where the lumbar vessels are. As far as we know, there are only a few studies investigating the location of the lumbar arteries. This study evaluates the anatomical position of lumbar arteries using magnetic resonance imaging (MRI). METHODS: We studied 101 MRIs of patients with lumbar disease. The length from the upper and lower end plates of the vertebra to the lumbar arteries was measured. The measurement was conducted with coronal MRI images of every quarter slice of L1 to L4 vertebrae. We also investigated sagittal MRI images to determine whether the lumbar vessels are located on intervertebral disc in each level from L1/2 to L5/S1. RESULTS: The lumbar vessels are not always located at the center of the vertebrae. Some lumbar vessels are located within 8 mm from the end plates. Especially in L4, the lumbar vessels tended to go down from the anterior cranial side to the posterior caudal side (P < 0.01). 8, 24, and 54 lumbar vessels are located at the anterior quarter, the center, and the posterior quarter slice of the vertebrae, respectively, in L4. There were seven lumbar vessels in total located on the vertebral disc level. CONCLUSIONS: It is necessary to investigate where the lumbar arteries are located to prevent its injury in LLIF, because the lumbar artery is not always located at the center of a vertebra. MRIs may provide a valuable information to avoid vascular injury during LLIF.

A Case of Spontaneous Regression of Recurrent Desmoid Tumor Originating From the Internal Obturator Muscle After Delivery.

Desmoid-type fibromatoses are pathologically benign but locally aggressive tumors. We report the case of a desmoid tumor that disappeared spontaneously after recurrence. A 21-year-old woman was referred to our hospital because of left lower limb weakness during menstruation. The following day this weakness had disappeared but menstrual colic remained; consequently, the patient underwent an internal examination that revealed an intrapelvic tumor. Magnetic resonance imaging demonstrated an enhanced mass (diameter, 8 cm) arising from the internal obturator muscle and attached to the urinary bladder. The tumor was diagnosed as a desmoid-type fibromatosis after histologic evaluation of a transvaginal biopsy; marginal resection was carried out at < 1 month after the first hospital admission. The patient experienced recurrence at 2 years after surgery, which was confirmed as two enhanced masses (diameter, 1 cm) using magnetic resonance imaging. Eleven months later, the diameters of these masses had increased to 1.8 cm; however, there was no further increase in size beyond this point. The patient delivered successfully at 5 and 7 years after surgery; at 8 years, the recurrent tumors had disappeared completely as confirmed by magnetic resonance imaging. This case involving recurrence is rare for two reasons. The first was that no change in the size of the tumors occurred during pregnancy and after delivery, and the second was that the patient experienced complete remission of the recurrent tumors after only simple observation. Thus, it is important to recognize that even a recurrent desmoid tumor can sometimes exhibit spontaneous regression.

Gender difference in the development of steroid-induced osteonecrosis in rabbits.

OBJECTIVE: To investigate the incidence of steroid-induced osteonecrosis (ON) among male and female rabbits. METHODS: Forty-seven adult rabbits (male, n = 24; female, n = 23) were injected once intramuscularly into the right gluteus medius muscle with 20 mg/kg of methylprednisolone acetate. Haematological examinations were performed just before and at 1 and 2 weeks after the steroid injection. Two weeks after the injection, both femora and humeri were histopathologically examined for the presence of ON, and the bone marrow fat cells were examined morphologically. RESULTS: Sixteen of 24 male rabbits (66.7%) and 5 of 23 female rabbits (21.7%) developed ON. There was a significant difference in the rate of incidence of ON between male and female rabbits (P = 0.0032). Haematologically, at 1 week after the steroid injection, both the mean low-density lipoprotein (LDL) and the ratio of LDL cholesterol to high-density lipoprotein cholesterol in the male rabbits were significantly higher than those in the female rabbits (P = 0.0001 for both comparisons). The bone marrow fat cells of the male rabbits [61.5 (5.6) microm] were significantly larger than those of the female rabbits [58.9 (3.7) microm; P = 0.0102]. CONCLUSION: This study indicates that gender may be an important factor in considering the pathogenesis of steroid-induced ON.

Dose effects of corticosteroids on the development of osteonecrosis in rabbits.

OBJECTIVE: The relationship between dose of corticosteroids and the prevalence of osteonecrosis (ON) has not been established. We examined the dose effects of corticosteroids on the development of ON in a rabbit model. METHODS: Rabbits were injected once intramuscularly with 1 (12 rabbits), 5 (12 rabbits), 20 (20 rabbits), and 40 (25 rabbits) mg/kg of methylprednisolone acetate (MPSL) into the right gluteus medius muscle. Four weeks after the MPSL injection, the proximal and distal parts of both the femora and humeri were histopathologically examined for the presence of ON. Hematological examinations were performed before and after the corticosteroid injection. RESULTS: In rabbits with 1, 5, 20, and 40 mg/kg MPSL, the incidence of ON was 0, 42%, 70%, and 96%, respectively. The dose of MPSL showed a significant association with the incidence of ON. Histologically, reparative tissues around the ON sites were observed in the rabbits with 5 mg/kg MPSL, but not observed in rabbits with 20 and 40 mg/kg MPSL. On hematological examination, hyperlipidemia and thrombocytopenia were most apparent in the rabbits receiving 40 mg/kg MPSL. CONCLUSION: The study suggested that the dose of corticosteroids plays an important role in the development of ON in rabbits. The repair process was also found to be influenced by the dose of corticosteroids. Corticosteroid-induced hyperlipidemia and thrombocytopenia seemed to be associated with the incidence of ON.

Pitavastatin may reduce risk of steroid-induced osteonecrosis in rabbits: a preliminary histological study.

Several animal and human studies suggest pharmacological approaches may prevent steroid-induced osteonecrosis (ON). We asked whether the newly developed 3-hydroxymethyl-3-glutaryl-CoA (HMG-CoA) reductase inhibitor, pitavastatin, could prevent steroid-induced ON in rabbits. We injected 65 adult male Japanese white rabbits once with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were divided into two groups; one group of 35 rabbits received pitavastatins (PS), and the other group of 30 rabbits received no prophylaxis (CTR). Hematological examinations were performed just before the steroid injection (0 weeks) and at 1 and 2 weeks after steroid injection; both the femora and the humeri were histologically examined 2 weeks postinjection. The incidence of histologic changes consistent with early ON in the PS group (13 of 35; 37%) was lower in comparison to the CTR group (21 of 30; 70%). The size of the bone marrow fat cells in the PS group (56.6 +/- 10 microm) was smaller than those in the CTR group (60 +/- 4 microm). The data suggest pitavastatin has the potential to lower the incidence of steroid-induced ON in rabbits.

[Animal models for steroid-induced osteonecrosis].

We describe that high-dose methylprednisolone (20 mg/kg) can induce multifocal osteonecrosis (ON) in conjunction with thrombocytopenia, hypofibrinogenemia, and hyperlipemia. Detailed clinical and laboratory evaluations of coagulation system are recommended in those patients who develop manifestations of an abnormal lipid metabolism shortly after high-dose corticosteroid therapy. Moreover, we investigated the effects of the combination treatment with an anticoagulant (warfarin) plus a lipid-lowering agent (probucol) on prevention of steroid-induced osteonecrosis (ON) in this animal model. The incidence of ON in warfarin plus probucol (5%) was significantly lower than that observed in the control group (70%) (p <0.0001). Our results experimentally showed that the combined use of an anticoagulant and a lipid-lowering agent helps prevent steroid-induced ON in rabbits.

Early MRI findings of the acetabulum and femoral head in a dysplastic hip resulting in a rapid destruction of the hip joint.

We documented a case of rapidly destructive arthrosis of the hip joint (RDA), in whom abnormal findings were observed not only in the femoral head but also in the acetabulum on magnetic resonance images (MRI) in the early stage. Radiographs made 1 month after the onset of pain showed a slight narrowing of the joint space. MRI obtained 2 months after the onset detected small foci of low signal intensity in the subchondral area of the femoral head on the T1-weighted images, and a linear pattern of high signal intensity in the lateral side of the acetabulum on the T2-weighted images. During the 17-month follow-up period, this case eventually underwent massive destruction of the femoral head as well as the acetabulum.