Floating spine after pedicle subtraction osteotomy for post-traumatic kyphosis.

PURPOSE: Pedicle subtraction osteotomy (PSO) was developed to achieve significant correction of a deformity. It was initially used to correct sagittal plane deformities associated with ankylosing spondylitis, but recently it has also been performed in patients with post-traumatic kyphosis. Our aim was to report a case of a floating spine after PSO for post-traumatic kyphosis. METHODS: A 50-year-old man was injured after a fall. He had a compression fracture at T12 and an open fracture of the right lower limb. Although he presented with focal back pain, his open fracture was treated first by surgical intervention. The T12 compression fracture was treated conservatively. One year later, he had lower limb numbness and muscle weakness. His imaging demonstrated focal kyphosis on T12 and spinal cord compression. The diagnosis was post-traumatic kyphosis, which was treated with PSO. We performed osteotomy at T12, discectomy and bone graft at T11-T12, and posterior fusion from T10 to L2. RESULTS: One year after PSO, we removed the instruments because he complained of pain around them and found complete bony union between T11 and T12. He immediately experienced worse pain and could not walk or stand for more than 10 min. Imaging showed a floating spine between T12 and L1. He underwent anterior fusion at T12-L1, after which his severe back pain disappeared. CONCLUSIONS: This case points out a pitfall of PSO. Although it is a powerful tool for correcting an imbalanced spine, we should recognize its pitfalls and try to avoid them.

Assessment of pure single nerve root resection in the treatment of spinal schwannoma: focus on solitary spinal schwannomas located below the thoracolumbar junction.

BACKGROUND: The incidence of neurological deficits is reportedly low after sacrificing the affected nerve root during spinal schwannoma treatment. Although the incidence has been widely reported, the operative method for nerve root resection has been not clarified. To evaluate the safety of pure nerve root resection, we focused on solitary spinal schwannomas below the thoracolumbar level and investigated the effect of affected nerve resection. METHODS: Twenty-three spinal schwannoma patients were retrospectively examined. The mean age at surgery was 53 years. We investigated preoperative symptoms, duration of the disorder, postoperative neurological deficits, and clinical outcomes. In addition, we measured tumor size on computed tomography after myelography or on magnetic resonance images using image-analysis software. We retrospectively assessed correlations among duration of symptoms, tumor size, and postoperative neurological deficits. RESULTS: The tumors comprised 19 intradural schwannomas and 4 dumbbell-shaped schwannomas. No postoperative neurological deficits were observed in the intradural schwannoma patients. In contrast, three of the four dumbbell-shaped schwannoma patients experienced postoperative neurological deficits. Among these three patients, two recovered quickly whereas one never recovered. The mean duration of the disorder was 29 months. The postoperative modified JOA score (13.0) was significantly improved compared with the preoperative score (8.9). The mean maximum tumor sizes were 97.2 mm(2) for the intradural schwannomas and 884.0 mm(2) for the dumbbell-shaped schwannomas. There were no correlations among tumor size, duration of the disorder, and postoperative neurological deficits. CONCLUSIONS: On the basis of this study, we recommend pure single nerve resection for treatment of intradural spinal schwannomas before such tumors progress and involve other normal roots, because postoperative neurological deficits did not occur in our intradural schwannoma patients, irrespective of tumor size, when this procedure was used. However, dumbbell-shaped schwannoma patients should be carefully treated operatively, because high incidence of postoperative neurological deficits can be expected.

Bone formation-promoting effect of genistein on marrow mesenchymal cell culture.

The effect of genistein, a soybean isoflavone, on new bone formation by bone marrow cells from mature rats and humans was examined. Bone marrow cells were collected from the femoral diaphysis of 7-week-old Fisher rats, cultured in MEM containing fetal calf serum and then cultured with or without the addition of dexamethasone to the bone-forming medium. Genistein was added at concentrations of 10(-5),10(-6),10(-7) or 10(-8) M. Bone formation was examined 2 weeks after culture. After informed consent was obtained from a 55-year-old woman with lumbar spondylosis deformans, bone marrow cells were collected from her ilium for culture by the same process, and bone formation investigated. In both rats and humans, when dexamethasone was added to the bone-forming medium, genistein (10(-7) M and 10(-8) M) caused a significant increase in the levels of calcium, alkaline phosphatase, and DNA compared with cells not cultured in genistein. In conclusion, genistein was found to promote bone formation at lower concentrations across species, and thus may be useful as a bone formation-promoting factor.

Osteogenic potential of cultured bone/ceramic construct: comparison with marrow mesenchymal cell/ceramic composite.

Osteogenesis occurs in porous hydroxyapatite (HA) when porous HA blocks combined with marrow mesenchymal cells are grafted in vivo. In vitro bone formation occurs in HA pores when HA combined with marrow cells is cultured in osteogenic medium containing dexamethasone. This cultured bone/HA construct possesses higher osteogenic ability when it is grafted in vivo. In the present study, we compared the osteogenic potential of a cultured bone/HA construct with that of a marrow mesenchymal cell/HA composite. Marrow cells were obtained from the femoral bone shaft of 7-week-old, male Fischer 344 rats and were cultured in T-75 flasks. Cells were concentrated, then frozen and stored in liquid nitrogen for 6 months. The cryopreserved cells were then thawed and prepared for subculture in porous HA (5 x 5 x 5 mm, Interpore 500) and for implantation with porous HA. After 2 weeks of subculture, three cultured bone/HA constructs were separately implanted in the right side of the back of each syngeneic 7-week-old male Fischer rat, and three thawed cell/HA composites (without subculture) were separately implanted in the left side. These implants were harvested at 2 or 4 weeks postimplantation, and prepared for histological, biochemical, and genetic analysis. Alkaline phosphatase activity and osteocalcin content of cultured bone/HA constructs were much higher than those of the cell/HA composites at 2 and 4 weeks postimplantation. Histological examination and gene expression data agreed with these findings. The culture technique discussed herein should facilitate the development of biosynthetic bone implants with higher osteogenic capacity.

Bone regeneration by grafting of an autogenous cultured bone/ceramic construct.

The in vivo osteogenic potential of autogenous cultured bone/ceramic constructs in large animals or humans is unknown, and thus we performed a preliminary study of this issue prior to clinical application. All autogenous cultured-bone/ceramic constructs at 3 weeks after implantation in dogs showed obvious histological bone formation within the ceramic pores. In many pores, the HE staining of decalcified specimens revealed thick lamellar bone formation on the pore surface of ceramic. On the surface of bone tissue, numerous active cuboidal osteoblasts were evident. Biochemically, high alkaline phosphatase activity was detected in all dogs. Histological examination of the constructs at 8 weeks postimplantation showed lamellar bone formation with vascular system invasion into the pores, and regenerated hematopoietic bone marrow was often detected in association with the new bone in grafting of human cultured bone/ceramic constructs. Trilineage hematopoietic cells (i.e., granulocytic, erythroblastic, and megakaryocytic cells) were identified in the ceramic pores. Biochemically, high alkaline phosphatase activity and significant human osteocalcin content was detected in the constructs. Based on these findings, in the near future, this technique (grafting of patient-derived cultured bone/HA constructs) will be able to be applied to various bone reconstruction surgical treatments.

Magnification error in digital radiographs of the cervical spine against magnetic resonance imaging measurements.

STUDY DESIGN: Prospective study. PURPOSE: The main purpose of this study was to clarify the range of magnification errors on digital plain radiographs and to determine if there is a correlation between the body mass index (BMI) of a patient and the magnification error. OVERVIEW OF LITERATURE: Most clinicians currently use digital plain radiography. This new method allows one to access images and measure lengths and angles more easily than with the past technologies. In addition, conventional plain radiography has magnification errors. Although few articles mention magnification errors in regards to digital radiographs, they are known to have the same errors. METHODS: We used plain digital radiography and magnetic resonance imaging (MRI) to acquire images of the cervical spine with the goal of evaluating magnification errors by measuring the anteroposterior vertebral body lengths of C2 and C5. The magnification error (ME) was then calculated: ME=(length on radiograph-length on MRI)/length on MRI ×100 (%). The correlation coefficient between the magnification error and BMI was obtained using Pearson's correlation analysis. RESULTS: Average magnification errors in C2 and C5 were approximately 18.5%±5.4% (range, 0%-30%) and 20.7%±6.3% (range, 1%-32%). There was no positive correlation between BMI and the magnification error. CONCLUSIONS: There were magnification errors on the digital plain radiographs, and they were different in each case. Maximum magnification error differences were 30% (C2) and 31% (C5). Based on these finding, clinicians must pay attention to magnification errors when measuring lengths using digital plain radiography.

Posterior Fixation of a Cervical Fracture Using the RRS Loop Spine System and Polyethylene Tape in an Elderly Ankylosing Spondylitis Patient: A Case Report.

An 80-year-old woman presented with neck pain and paraparesis of Frankel C in her upper and lower extremities after falling. Imaging revealed an ankylosing cervical spine and a fracture line running obliquely from the anterior C3-4 to the posterior C4-5 level. Posterior fixation from the occi pit to T3 was performed using the RRS Loop Spine System and concomitant polyethylene tape fixation. This system is characterized by the uniqueness of how it screws to the occi pit and its use of a fixation rod with a larger diameter than in other instrumentation devices for use in the cervical region. Sublaminar banding using polyethylene tape was used to secure fixation. Her postoperative course was unremarkable, and her neck pain was relieved, although neurological improvement was minor. To our knowledge, this is the first report of an application of the RRS Loop Spine System to an ankylosing spondylitis patient with a cervical fracture.

Cervical laminoplasty combined with muscle release in patients with athetoid cerebral palsy.

STUDY DESIGN: A retrospective study comparing cervical laminoplasty with or without muscle release for the treatment of cervical myelopathy resulting from athetoid cerebral palsy. OBJECTIVE: To assess the effectiveness of muscle release in the treatment of athetoid cerebral palsy. SUMMARY OF BACKGROUND DATA: While anterior and/or posterior spinal fusion has been generally accepted as necessary in surgical treatment for cervical myelopathy due to athetoid cerebral palsy, several studies have shown relatively favorable results following laminoplasty. Better results can be obtained by combining muscle release. METHODS.: Study participants were 10 patients who underwent cervical laminoplasty combined with muscle release (mean age, 44.6 years) and 15 patients who underwent cervical laminoplasty alone (mean age, 48.2 years). Therapeutic outcomes 1 year after surgery, as assessed by Kurokawa's methods and JOA scores, were compared between groups. RESULTS: Recovery rate 1 year after surgery was significantly higher for the muscle release group than for the control group. In both groups, recovery rates were significantly better for patients who could walk before surgery. CONCLUSIONS: Cervical laminoplasty combined with muscle release for the treatment of cervical myelopathy due to athetoid cerebral palsy is effective in simplifying postoperative therapy and improving JOA scores.

Upper thoracic spinal cord injury without vertebral bony lesion: a report of two cases.

STUDY DESIGN: Case report. OBJECTIVES: To describe a rarely reported type of upper thoracic spinal cord injury without vertebral bony lesion in two cases with multiple trauma. SUMMARY OF BACKGROUND DATA: Because it is supported by the stiffness of the rib cage, the upper thoracic spine has greater stability than the cervical and lumbar regions, and thus its fracture or fracture dislocation is less frequent. Nevertheless, when fracture or fracture dislocation of upper thoracic spine occurs, spinal cord involvement and severe concomitant injuries are frequently associated. METHODS: Two cases who were suspected to have thoracic spinal cord injuries were referred to our emergency center: a 19-year-old girl presented with paraparesis after her motorcycle collided with a truck, and a 63-year-old male involved in an industrial accident presented with paraplegia. RESULTS: Radiograph and computed tomography scan showed no abnormality or dislocation in the vertebral bodies in these two cases, although the upper thoracic spinal cord injuries were suspected by clinical features. Magnetic resonance images detected abnormal signals, suggesting spinal cord injuries, and these signals each emanated from levels that coincided with the observed clinical features. CONCLUSIONS: Transient subluxation or displacement might have caused the upper thoracic spinal cord injuries after the support of the rib cages was temporarily lost on application of excessive force, although such findings could not be confirmed by imaging procedures.