Association of spinal anomalies with spondylolysis and spina bifida occulta.

PURPOSE: To investigate the association of spinal anomalies with lumbar spondylolysis and spina bifida occulta (SBO). METHODS: A total of 1190 patients with thoracic, abdominal, and pelvic computed tomography scans available were categorized according to the number of presacral (thoracic and lumbar) mobile vertebrae and the presence or absence of lumbosacral transitional vertebrae (LSTV). The prevalence of spondylolysis and SBO and the association of spinal anomalies with these disorders were evaluated. RESULTS: Normal morphology (17 mobile vertebra with no LSTV) was found in 607 men (86.5%) and 419 women (85.9%) and about 14% of patients had anomalies. Spondylolysis was found in 74 patients (6.2%), comprising 54 men (7.7%) and 20 women (4.1%). SBO involving the lumbar spine was found in 9 men (1.3%) and 2 women (0.4%). Spondylolysis was significantly more common in men with 18 vertebrae without LSTV (21.1%) than in those with 17 vertebrae without LSTV (7.2%) (p = 0.002). The prevalence of spinal anomalies was 55.6% in men and 50.0% in women with SBO that included a lumbar level was significantly higher than in both men (13.5%, p < 0.001) and women (4.8%, p = 0.003) without SBO. CONCLUSION: These findings indicate that there is a relationship between spinal anomalies and both spondylolysis and SBO, which may lead to elucidation of the mechanism of onset of spondylolysis and improve its treatment and prognosis. Awareness that patients with SBO involving the lumbar spine have an increased likelihood of a spinal anomaly may help to prevent level errors during spinal surgery.

Age-related changes in axial and sagittal orientation of the facet joints: Comparison with changes in degenerative spondylolisthesis.

BACKGROUND: Despite facet joints being three-dimensional structures, previous computed tomography and magnetic resonance imaging studies have evaluated facet joint orientation in only the axial plane. Facet joint orientation in the sagittal plane has rarely been studied using these imaging techniques. The aim of this study was to elucidate facet joint orientation in both the axial and sagittal planes on computed tomography. METHODS: A total of 568 patients (343 men, 225 women) (excluding orthopedic outpatients) for whom abdominal and pelvic computed tomography scans were obtained at our hospital between September 2010 and October 2012 were included. Mean age was 63 (range 21-90) years. Patients were divided into a degenerative spondylolisthesis group (67 patients; 30 men, 37 women) and a control group (313 patients; 313 men, 188 women). Facet joint orientation was evaluated in the control group according to patient age (≤50, 51-60, 61-70, or ≥71 years). The findings in the control group were then compared with those in the degenerative spondylolisthesis group. The orientation of the lumbar facet joints at each level was measured in the axial and sagittal planes on computed tomography images. RESULTS: Facet joint angles decreased with age at L4/5 and L5/S1 in women in the axial plane and at L4/5 in men and L3/4 and L4/5 in women in the sagittal plane. The variation in facet joint angle was greatest at L4/5 in women. Patients with degenerative spondylolisthesis showed more sagittally and horizontally oriented facet joints in the axial and sagittal planes; facet tropism showed an association with degenerative spondylolisthesis in the axial plane. CONCLUSIONS: The axial and sagittal orientation of facet joints in the lower lumbar vertebra, especially L4/5, was negatively correlated with age. This finding could help to explain why older people are more prone to degenerative spondylolisthesis.

Native rotational knee kinematics are lost in bicruciate-retaining total knee arthroplasty when the tibial component is replaced.

PURPOSE: To compare the kinematics between native knees and knees that have undergone bicruciate-retaining (BCR) total knee arthroplasty (TKA) with cruciate-retaining (CR) TKA converted from BCR TKA in the same whole-body cadaveric specimen using a navigation system and, if differences exist, to investigate the point at which normal kinematics are lost during the procedure. METHODS: The rotational kinematics throughout passive flexion of the native knee and of knees after meniscectomy, femoral replacement, BCR TKA, or CR TKA were assessed in nine fresh frozen cadavers using an image-free navigation system. RESULTS: The rotational kinematic pattern of a knee after BCR TKA was different from that of a native knee, especially in the early flexion phase, and was similar to that after CR TKA. Screw-home movement was not observed after BCR TKA, but still occurred after meniscectomy or femoral replacement with intact cruciate ligaments and an intact tibial articular surface. CONCLUSION: The rotational kinematics of the native knee are not always preserved after BCR TKA. Native rotational kinematics are preserved after meniscectomy and femoral replacement, but are lost after tibial replacement in BCR TKA. Surgeons should pay close attention to maintain the anteroposterior stabilizing function of the ACL in BCR TKA, rather than to restore the native rotational kinematics.

Location and direction of the nutrient artery to the first metatarsal at risk in osteotomy for hallux valgus.

BACKGROUND: Osteotomy for hallux valgus interrupts intraosseous blood supply to the first metatarsal, presumably causing non-union, delayed union, or osteonecrosis of the head of the first metatarsal. We investigated the first metatarsal nutrient artery, arising from the first dorsal metatarsal artery, and identified aspects of surgical technique contributing to nutrient artery injury. METHODS: Enhanced computed tomography scans of 8 feet of 8 fresh cadavers were assessed. Barium was injected through the external iliac artery; location and direction of the first metatarsal nutrient artery was recorded. RESULTS: Mostly, the nutrient artery entered the first metatarsal at the distal third or junction of the middle and distal thirds obliquely from a proximal direction coronally; entry point and direction varied axially. Saw blade overpenetration alone or with extensive capsular stripping might damage the artery. CONCLUSIONS: Location and direction of the first metatarsal nutrient artery was established.

Study of lesions of the lumbar endplate based on the stage of maturation of the lumbar vertebral body: the relationship between skeletal maturity and chronological age.

The lesion of the lumbar endplate is sometimes identified in the vertebrae of children and adolescents. The purpose of this study is to compare between skeletal maturity and chronological age. The second purpose of this study is to clarify the lesions of the lumbar endplate based on the maturation of the lumbar vertebral body. Six hundred and thirty-two (485 men and 147 women) consecutive patients were included. The mean age at the first medical examination was 13.8 years. Their skeletal maturity was evaluated based on the appearances of the secondary ossification center of L3. The area of the endplate lesions was classified into five types. The apophyseal stage was observed from 10 years old to 18 years old, and the apophyseal stage was shown the peak at 14 years old. The appearance of the apophyseal ring was observed earlier in female patients than in male patients. For the concave type, the lesion at upper level vertebra was more prevalent. The anterior and middle type of the lesion at upper level vertebra was more prevalent. For the posterior type, the lesion of the inferior rim of L4 and the lesion of the rim of L5 were more prevalent. This study emerged after comparing skeletal maturity based on the maturation of the lumbar vertebral body with the chronological age of a large number of patients and examining the lesions of the lumbar endplate based on the stage of maturation of the lumbar vertebral body.

Influence of Medial Collateral Ligament Release for Internal Rotation of Tibia in Posterior-Stabilized Total Knee Arthroplasty: A Cadaveric Study.

BACKGROUND: Previous studies suggested that changes in kinematics in total knee arthroplasty (TKA) affected satisfaction level. The aim of this cadaveric study was to evaluate the effect of medial collateral ligament (MCL) release by multiple needle puncture on knee rotational kinematics in posterior-stabilized TKA. METHODS: Six fresh, frozen cadaveric knees were included in this study. All TKA procedures were performed with an image-free navigation system using a 10-mm polyethylene insert. Tibial internal rotation was assessed to evaluate intraoperative knee kinematics. Multiple needle puncturing was performed 5, 10, and 15 times for the hard portion of the MCL at 90° knee flexion. Kinematic analysis was performed after every 5 punctures. After performing 15 punctures, a 14-mm polyethylene insert was inserted, and kinematic analysis was performed. RESULTS: The tibial internal rotation angle at maximum knee flexion without multiple needle puncturing was significantly larger (9.42°) than that after 15 punctures (3°). Negative correlation (Pearson r = -0.715, P < .001) between tibial internal rotation angle at maximum knee flexion and frequency of puncture was observed. The tibial internal rotation angle with a 14-mm insert was significantly larger (7.25°) compared with the angle after 15 punctures. CONCLUSION: Tibial internal rotation during knee flexion was reduced by extensive MCL release using multiple needle puncturing and was recovered by increasing of medial tightness. From the point of view of knee kinematics, medial tightness should be allowed to maintain the internal rotation angle of the tibia during knee flexion which might lead to patient satisfaction.

Proteomic Analysis of Human Tendon and Ligament: Solubilization and Analysis of Insoluble Extracellular Matrix in Connective Tissues.

Connective tissues such as tendon, ligament and cartilage are mostly composed of extracellular matrix (ECM). These tissues are insoluble, mainly due to the highly cross-linked ECM proteins such as collagens. Difficulties obtaining suitable samples for mass spectrometric analysis render the application of modern proteomic technologies difficult. Complete solubilization of them would not only elucidate protein composition of normal tissues but also reveal pathophysiology of pathological tissues. Here we report complete solubilization of human Achilles tendon and yellow ligament, which is achieved by chemical digestion combined with successive protease treatment including elastase. The digestion mixture was subjected to liquid chromatography-mass spectrometry. The low specificity of elastase was overcome by accurate mass analysis achieved using FT-ICR-MS. In addition to the detailed proteome of both tissues, we also quantitatively determine the major protein composition of samples, by measuring peak area of some characteristic peptides detected in tissue samples and in purified proteins. As a result, differences between human Achilles tendon and yellow ligament were elucidated at molecular level.

Variations in arterial supply to the lower lumbar spine.

PURPOSE: Several papers examined the vascular anatomy of the lumbosacral region using cadavers with angiography. However, few reports used CT angiography, and discussion on variations of fourth lumbar, fifth lumbar, and lumbar branch of iliolumbar arteries were limited. To clarify the vascular variations around the lower lumbar spine including the lumbosacral region, particularly at the posterior elements, we performed anatomical analysis using computed tomography (CT). METHODS: Extra-osseous arteries surrounding the lumbar spine including the lumbosacral region were evaluated by two orthopedic surgeons independently, using 323 consecutive abdominal contrast-enhanced multi-planner CT scans that were taken for surgical plans in colon cancer patients. Subjects were 204 men and 119 women, whose ages ranged from 15 to 89 years (mean 66.5). RESULTS: Each segmental artery was visible at the L1-4 spinal levels, running from the vertebra through the lamina in 91.0 % on the right side, in 90.7 % on the left side, while it was visible in 4.6 % on the right side, in 8.7 % on the left side at the L5 level. The extra-osseous arterial supply to the L5 lamina was basically provided by two vessels on each side. One was mostly derived from the L4 segmental artery (right: 92.6 %; left: 92.0 %) that was distributed around the superior articular process, the other was derived from the iliolumbar artery (right: 62.9 %; left: 55.7 %) that was distributed around the inferior articular process through the lamina. There were mainly four combination patterns of those arteries. These combinations, which had been considered as regular patterns in textbooks, were observed in approximately 50 % (right: 55.7 %; left: 48.6 %) of patients. CONCLUSION: Various distributions of arteries around the lower spine were identified.

Characteristics of lumbar spondylolysis in elementary school age children.

PURPOSE: Lumbar spondylolysis, a stress fracture of the pars interarticularis in the lumbar spine, is often precipitated by trauma, but there may be a congenital predisposition to this condition. There have been few studies on spondylolysis in young children, despite their suitability for studies on congenital defects. The aim of this study was to identify the clinical features of lumbar spondylolysis in elementary school age children in order to elucidate its pathogenesis. METHODS: Thirty lumbar spondylolysis patients (23 boys, 7 girls, including a pair of twins; mean age 9.5 years, age range 5-12 years) were studied. Patient data on history of athletic activity, symptoms at first consultation, and radiological findings such as spinal level, stage of the stress fracture, and skeletal age were collected. RESULTS: Among the 30 patients, 27 (21 boys, 6 girls) had L5 spondylolysis (90.0 %). Only 2 patients had no history of athletic activity at the first consultation. All patients, except for 2 whose diagnosis was incidental, complained of low back pain. In the 27 patients with L5 spondylolysis, 17 (63.0 %) had terminal-stage fracture and 25 (92.6 %) had spina bifida occulta (SBO) involving the S1 lamina. Sixteen of the 27 (59.3 %) had SBO involving the affected lamina (L5) and S1 lamina. In contrast, the 3 patients with L3 or L4 spondylolysis had no evidence of SBO. With respect to skeletal age, 23 of the 27 L5 spondylolysis patients (85.2 %) were in the cartilaginous stage while the remaining 4 patients were in the apophyseal stage. CONCLUSION: Lumbar spondylolysis in elementary school age children was commonly a terminal-stage bone defect at L5, which was not necessarily related to history of athletic activity and was sometimes asymptomatic. It was often associated with SBO, indicating a possible congenital predisposition. These findings may provide further insight into the pathogenesis of lumbar spondylolysis.

Comparison of femoroacetabular impingement-related radiographic features in a convenience sample of Japanese patients with and without herniation pits.

OBJECTIVE: To examine the prevalence of herniation pits (HPs) and to evaluate differences in radiographic features related to femoroacetabular impingement-a hip disorder with abnormal abutment between the acetabulum and femur-between hips with and without HPs in a convenience sample of Japanese patients. MATERIALS AND METHODS: We reviewed 1,178 hips on each side (695 men, 483 women; mean age, 58.2 years) using computed tomographic images. The radiological assessments of hip morphology were performed by measuring the lateral center edge angle, acetabular index, acetabular version, alpha angle, and femoral head-neck offset. HPs were defined as the round or oval cystic lesions surrounded by sclerotic bone located below the anterior femoral neck cortex. RESULTS: Intraclass and interclass reproducibility of all radiographic measurements was acceptable (ICC: 0.71-0.98). The prevalence of HPs was 13.9 % in all subjects and was significantly higher in men (18.1 %) than in women (7.8 %; p < 0.001). HPs were larger in male (p < 0.001) and elderly subjects (p < 0.005). In subjects with HPs, the alpha angle was larger and femoral head-neck offset and offset ratio were smaller in the cohort overall and in men. Logistic regression analysis revealed the association between radiological cam-type FAI and HPs in all subjects (odds ratio: 1.86, p < 0.001). CONCLUSIONS: We revealed the prevalence of HPs and showed it has a predilection for men in this Japanese cohort. Femoral head asphericity or small head-neck offset was more common in subjects with HPs than those without HPs.

Correlation between coxa profunda and morphological parameters of acetabular coverage in a Japanese cohort: A CT study.

BACKGROUND: Coxa profunda is generally considered an indicator of acetabular overcoverage. However, recent studies have opposed this view. The correlation between coxa profunda and acetabular overcoverage thus remains controversial. The purpose of this study was to investigate the prevalence of coxa profunda and the association between coxa profunda and acetabular coverage based on sex in Japanese subjects using computed tomography. METHODS: We reviewed the computed tomography scans of 151 Japanese consecutive patients (302 hips) aged <50 years who underwent abdominopelvic computed tomography for symptoms unrelated to hip disease. Coxa profunda was diagnosed when the floor of the acetabular fossa touched or was medial to the ilioischial line. We measured the lateral center edge angle, acetabular roof obliquity angle, acetabular version, and anterior and posterior acetabular sector angles as parameters of acetabular coverage. RESULTS: Coxa profunda was observed in 45.7% of all subjects, and was more common in females (63.0%) than in males (29.5%). We found no significant differences in the incidence of coxa profunda among subjects with dysplasia, overcoverage, and normal coverage. Males with coxa profunda showed significantly greater lateral center edge angle, anterior acetabular sector angle, and lower acetabular roof obliquity angle, whereas anterior and posterior acetabular sector angles were greater in all subjects and females with coxa profunda. Coxa profunda showed poor sensitivity (57.7%) and specificity (56.8%) for detecting overcoverage in all subjects. CONCLUSIONS: Coxa profunda is a common radiographic feature in Japanese patients, especially in women. Coxa profunda may be less useful for diagnosing acetabular overcoverage because of its common occurrence with various hip morphologies and its poor specificity for detecting acetabular overcoverage. However, men with coxa profunda have greater acetabular coverage, so coxa profunda may contribute to acetabular coverage in men. We should take into account that coxa profunda may have different implications between the sexes.

Clinical features of patients with pars defects identified in adulthood.

PURPOSE: Lumbar spondylolysis is considered a stress fracture of the pars interarticularis that occurs during growth. However, it is sometimes insidious and identified in adults as pseudoarthrosis, the terminal-stage of spondylolysis. The purpose of this study was to identify the clinical features of patients with terminal-stage spondylolysis that first manifested during adulthood. PATIENTS AND METHODS: Thirty-six patients (21 men, 15 women; mean age 55.8 years; age range 25-77 years) with low back pain (LBP) were studied. In all patients, lumbar spondylolysis had not been diagnosed until the first visit to our hospital. Patient data collected were history of athletic activity and LBP during their growth period and radiological findings, such as spinal level, displacement, and spina bifida occulta (SBO). RESULTS: Among the 36 patients, including a patient with multi-level spondylolysis (L4 and L5), a total of 37 vertebrae with terminal-stage spondylolysis were identified. Twenty-three (89.2 %) of the 37 vertebrae had L5 spondylolysis. Sixteen patients (44.4 %) had no history of athletic activity, 26 (72.2 %) had no experience of LBP during their growth period, and 14 (38.9 %) had neither. Twenty of the 37 vertebrae (70.4 %) involved displacement (grade 1 = 14; grade 2 = 6). In nine patients (25.0 %; eight men, one woman), SBO of the sacrum was accompanied by L5 spondylolysis. CONCLUSIONS: Approximately 90 % of patients with terminal-stage spondylolysis that was first diagnosed in adulthood involved the L5. Also, about 40 % had no history of athletic activity or experience of LBP during their growth period. In addition, only some patients with L5 spondylolysis had SBO, and all but one of these patients was male. This suggests that male patients with L5 spondylolysis may have some congenital predisposition.

Analysis of MRI signal changes in the adjacent pedicle of adolescent patients with fresh lumbar spondylolysis.

PURPOSE: The purpose of this study is to investigate a discrepancy between MRI and computed tomography (CT) findings in the spinal level distribution of spondylolysis. Recent advances in MRI have led to the early diagnosis of spondylolysis. Therefore, bony healing can be expected before the condition has a chance to worsen. In this study, we used MRI to examine the changes in spinal level signals in the pedicles adjacent to the pars interarticularis in adolescents with fresh lumbar spondylolysis. We then compared spinal level distribution of spondylolysis with that of previous results obtained by multidetector CT. METHODS: The study included 98 adolescent patients (31 women and 67 men; mean age, 13.6 years; age range, 9-18 years) with fresh lumbar spondylolysis who showed MRI signal changes in the adjacent pedicle. An MRI signal change was defined as a high signal change on fat-suppressed imaging. RESULTS: MRI signal changes were detected in 150 adjacent pedicles of 101 vertebrae. Of these vertebrae, MRI signal changes in only 67 (66.3%) corresponded to L5, while changes in 34 (33.7%) corresponded to L3 or L4. In our follow-up study, the bone-healing rate with no vertebral defect was 100% at L3, 97.1% at L4, and 84.4% at L5. In addition, 11 of 34 (32.4%) vertebrae with signal changes at L3 or L4 occurred with L5 terminal-stage spondylolysis (no MRI signal change). CONCLUSION: MRI revealed a higher prevalence of L3 or L4 spondylolysis than observed with CT.

Recurrence of type I Modic inflammatory changes in the lumbar spine: effectiveness of intradiscal therapy.

Here we report a case of recurrence of Modic type I inflammatory changes in the lumbar spine. A 49-year-old man was referred to our department with a history of chronic low back pain of at least 20 years. At the first consultation, he complained of low back pain only and had no other symptoms such as leg pain, numbness, or weakness. Although his pain was typically mild, he experienced one or two episodes of severe and incapacitating low back pain a year. After two intradiscal steroid injections, his pain disappeared immediately and completely. After 6 months of conservative treatment, Modic type I change switched to Modic type II change. However, 12 months after the first treatment, he once again experienced severe low back pain. Follow-up magnetic resonance imaging (MRI) indicated recurrence of Modic type I change that was stronger than the first occurrence. Two intradiscal injections relieved the pain. Six months after the second episode, follow-up MRI showed another switch of Modic type I change to Modic type II change. Switches of Modic change have been controversial, with mixed findings on pain, natural history, and degenerative changes. The present case reinforces the notion that Modic type I change corresponds to reversible local inflammation.

Pedicle screws can be 4 times stronger than lateral mass screws for insertion in the midcervical spine: a biomechanical study on strength of fixation.

STUDY DESIGN: A biomechanical study. OBJECTIVE: To compare, in cervical vertebrae (C3-C6), the pullout strengths of pedicle screws and lateral mass screws after both types of screw had been subjected to a period of cyclic loading in 2 planes. SUMMARY OF BACKGROUND DATA: In posterior subaxial cervical fixation systems, screws are usually inserted into the lateral mass. As an alternative to lateral mass fixation, pedicle screw fixation became popular in the 1990s and was first used for lower cervical spine trauma cases. However, it is controversial as to whether lateral mass screw fixation in the upper-middle cervical spine offers as much biomechanical security as compared with pedicle screw fixation. METHODS: For each of the 32 vertebrae, 1 side was randomly chosen to receive a pedicle screw and the other side a lateral mass screw. The pedicle or lateral mass screws inserted into the first 16 vertebrae were cyclically loaded to simulate torsion and the remaining 16 vertebrae were cyclically loaded to simulate flexion/extension of the spine. At the end of the cyclic loading each screw was pulled out along its long axis. RESULTS: For the torsion group, the mean pullout strength of the pedicle screws was nearly 4 times greater than the mean pullout strength of the lateral mass screws (cf 762 N with 191 N). In contrast, the mean pullout strength of the pedicle screws in the flexion/extension group was only twice the mean pullout strength of the lateral mass screws (cf 571 N with 289 N). CONCLUSIONS: Not forgetting the potential risks of inserting pedicle screws in cervical vertebrae, pedicle screws are a better biomechanical choice than lateral mass screws for cervical fixation at the levels C3 through to C6.

Performance of elastic x-ray shield made by embedding Bi2 O3 particles in porous polyurethane.

BACKGROUND: Many healthcare institutions have guidelines concerning the usage of protective procedures, and various x-ray shields have been used to reduce unwanted radiation exposure to medical staff and patients when using x-rays. Most x-ray shields are in the form of sheets and lack elasticity, which limits their effectiveness in shielding areas with movement, such as the thyroid. To overcome this limitation, we have developed an innovative elastic x-ray shield. PURPOSE: The purpose of this study is to explain the methodology for developing and evaluating a novel elastic x-ray shield with sufficient x-ray shielding ability. Furthermore, valuable knowledge and evaluation indices are derived to assess our shield's performance. METHODS: Our x-ray shield was developed through a process of embedding Bi2 O3 particles into porous polyurethane. Porous polyurethane with a thickness of 10 mm was dipped into a solution of water, metal particles, and chemical agents. Then, it was air-dried to fix the metal particles in the porous polyurethane. Thirteen investigational x-ray shields were fabricated, in which Bi2 O3 particles at various mass thicknesses (ranging from 585 to 2493 g/m2 ) were embedded. To determine the performance of the shielding material, three criteria were evaluated: (1) Dose Reduction Factor ( D R F $DRF$ ), measured using inverse broad beam geometry; (2) uniformity, evaluated from the standard deviation ( S D $SD$ ) of the x-ray image obtained using a clinical x-ray imaging detector; and (3) elasticity, evaluated by a compression test. RESULTS: The elastic shield with small pores, containing 1200 g/m2 of the metal element (Bi), exhibited a well-balanced performance. The D R F $DRF$ was approximately 80% for 70 kV diagnostic x-rays. This shield's elasticity was -0.62 N/mm, a loss of only 30% when compared to porous polyurethane without metal. Although the non-uniformity of the x-ray shield leads to poor shielding ability, it was found that the decrease in the shielding ability can be limited to a maximum of 6% when the shield is manufactured so that the S D $SD$ of the x-ray image of the shield is less than 10%. CONCLUSIONS: It was verified that an elastic x-ray shield that offers an appropriate reduction in radiation exposure can be produced by embedding Bi2 O3 particles into porous polyurethane. Our findings can lead to the development of novel x-ray shielding products that can reduce the physical and mental stress on users.

Early changes in muscle atrophy and muscle fiber type conversion after spinal cord transection and peripheral nerve transection in rats.

BACKGROUND: Spinal cord transection and peripheral nerve transection cause muscle atrophy and muscle fiber type conversion. It is still unknown how spinal cord transection and peripheral nerve transection each affect the differentiation of muscle fiber type conversion mechanism and muscle atrophy. The aim of our study was to evaluate the difference of muscle weight change, muscle fiber type conversion, and Peroxisome proliferator-activated receptor-γ coactivatior-1α (PGC-1α) expression brought about by spinal cord transection and by peripheral nerve transection. METHODS: Twenty-four Wistar rats underwent surgery, the control rats underwent a laminectomy; the spinal cord injury group underwent a spinal cord transection; the denervation group underwent a sciatic nerve transection. The rats were harvested of the soleus muscle and the TA muscle at 0 week, 1 week and 2 weeks after surgery. Histological examination was assessed using hematoxylin and eosin (H&E) staining and immunofluorescent staing. Western blot was performed with 3 groups. RESULTS: Both sciatic nerve transection and spinal cord transection caused muscle atrophy with the effect being more severe after sciatic nerve transection. Spinal cord transection caused a reduction in the expression of both sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection produced an increase in expression of sMHC protein and PGC-1α protein in the soleus muscle. The results of the expression of PGC-1α were expected in other words muscle atrophy after sciatic nerve transection is less than after spinal cord transection, however muscle atrophy after sciatic nerve transection was more severe than after spinal cord transection. CONCLUSION: In the conclusion, spinal cord transection diminished the expression of sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection enhanced the expression of sMHC protein and PGC-1α protein in the soleus muscle.

A Cadaveric Simulation Study of Radiation Exposure to the Surgical Team during Fluoroscopic Spinal Surgery: How Much Are We Exposed?

Introduction: The harmful effects of long-term low-dose radiation have been well known. There are few comprehensive reports evaluating concrete real exposure doses for each part of a surgeon, assistant surgeon, scrub nurse, and anesthesiologist associated with fluoroscopic spinal procedures. This research aimed to quantify the radiation exposure dose to surgical team members during C-arm fluoroscopy-guided spinal surgery. Methods: Seven fresh cadavers were irradiated for 1 and 3 min with C-arm fluoroscopy. The position of the X-ray source was under the table, over the table, and laterally. The radiation exposure doses were measured at the optic lens, thyroid gland, and hand in mannequins used to simulate surgical team members. Results: A significant difference was observed in the radiation exposure dose according to the position of the X-ray source and the irradiated body area. The risk of scatter radiation exposure was the biggest for the lateral position (nearly 30-fold that for the position under the table). All radiation exposure doses were positively correlated with irradiation time. Conclusions: The occupational radiation exposure dose to surgical team members during C-arm fluoroscopy-guided lumbar spinal procedures varies according to the X-ray source position. Our findings would help surgical team members to know the risk of radiation exposure during various fluoroscopic procedures. Surgeons in particular need to reduce their radiation exposure by using appropriate shielding and technique.

Radiation exposure doses to the surgical team during hip surgery is significantly higher during lateral imaging than posteroanterior imaging: a cadaveric simulation study.

BACKGROUND: Fluoroscopy is indispensable when determining appropriate and effective interventions in orthopedic surgery. On the other hand, there is growing concern about the health hazards of occupational radiation exposure. The aim of this cadaveric simulation study was to measure radiation exposure doses to the surgical team during hip surgery. METHODS: We reproduced the intraoperative setting of hip surgery using 7 fresh frozen cadavers (5 male, 2 female) to simulate patients and mannequins to simulate the surgeon, scrub nurse, and anesthesiologist. Six real-time dosimeters were mounted at sites corresponding to the optic lens, thyroid gland, chest, gonads, foot, and hand on each mannequin. The radiation exposure dose to each team member was measured during posteroanterior and lateral fluoroscopic imaging. RESULTS: Radiation exposure doses to the surgeon were significantly higher during 3 min of lateral imaging than during 3 min of posteroanterior imaging at the optic lens (8.1 times higher), thyroid gland (10.3 times), chest (10.8 times), and hand (19.8 times) (p = 0.018, p = 0.018, p = 0.018, and p = 0.018, respectively). During lateral imaging, the radiation doses to the nurse were 0.16, 0.12, 0.09, 0.72, and 0.38 times those to the surgeon at the optic lens, thyroid, chest, gonads, and foot, respectively. The radiation dose to the anesthesiologist was zero at all anatomic sites during posteroanterior imaging and very small during lateral imaging. CONCLUSIONS: Radiation exposure dose was significantly higher during lateral imaging up to 19.8 times comparing to the posteroanterior imaging. It is effective to reduce the lateral imaging time for reducing the intraoperative radiation exposure. In addition, appropriate distance from fluoroscopy resulted in very low exposure for nurses and anesthesiologists. Surgeon should pay attention that surgical staff do not get closer than necessary to the irradiation field.

The effect of spinal shortening after total en bloc spondylectomy: a biomechanical study in the thoracic spine.

STUDY DESIGN: A biomechanical study using human cadaveric thoracic spine specimens. OBJECTIVE: To evaluate and compare the biomechanical effects of spinal shortening and cross-links in reconstruction after total en bloc spondylectomy (TES). SUMMARY OF BACKGROUND DATA: There have been no studies that have examined the biomechanical effects of spinal reconstruction after multilevel TES or the biomechanical effects of spinal shortening in reconstruction after TES. METHODS: Eight human cadaveric spines (T2-T9) were used. After the intact specimen had been biomechanically tested to determine the stiffness in compression, flexion, extension, left and right lateral bending, and left and right axial rotation, a TES at T5-6 was carried out. Three reconstruction methods were tested biomechanically (same as for the intact specimen) for their ability to restore stiffness to the specimen: (1) anterior short cage and multilevel posterior instrumentation at T3-8 with 2 cross-links (S2C), (2) anterior short cage and multilevel posterior instrumentation at T3-8 with 1 cross-link (S1C), and (3) anterior long cage and multilevel posterior instrumentation at T3-8 with 2 cross-links (L2C). A cage that was 6-10 mm shorter in height than the space created by the TES at T5-6 was selected as the "short cage" and a cage 10 mm taller in height than the short cage was selected as the "long cage" in each specimen. RESULTS: All 3 reconstruction methods using an anterior cage and multilevel posterior instrumentation provides a stiffer construct than that shown by the intact specimen. The reconstruction method using the 10-mm shorter cage (S2C vs. L2C) provided more stiffness than the one using the longer cage. The reconstruction using 2 cross-links (S2C vs. S1C) did not provide a stiffer construct than the one using 1 cross-link. CONCLUSIONS: The reconstructions using an anterior cage and multilevel posterior instrumentation provided a stiffer construct than that shown by the intact specimen. The reconstruction using a 10-mm shorter cage provided a stiffer construct than the reconstruction using the longer cage.