Contrast-enhanced Magnetic Resonance Imaging in Patients With Dropped Head Syndrome.

STUDY DESIGN: This is a retrospective study of a consecutive case series of dropped head syndrome (DHS). OBJECTIVE: To identify the characteristic features of contrast-enhanced magnetic resonance imaging (MRI) in DHS patients. SUMMARY OF BACKGROUND DATA: Isolated neck extensor myopathy DHS is thought to be caused by severe cervical extensor muscle weakness from age-related loss of elasticity. However, the MRI findings of the cervical extensor muscles in DHS patients have not yet been characterized. MATERIALS AND METHODS: The subjects were 34 patients with isolated neck extensor myopathy DHS who underwent contrast-enhanced MRI within seven months after onset and 32 patients with age-matched cervical spondylosis or cervical soft-tissue tumor as controls. The presence of enhanced findings in the cervical extensor muscles, the involved cervical levels, and the characteristically enhanced shape of those muscles were evaluated using contrast-enhanced MRI. RESULTS: In the DHS group, the contrast-enhanced MRI showed pronounced enhancement at splenius capitis in 34 cases, rhomboid in 23 cases, semispinalis cervicis in seven cases, and levator scapulae in three cases. In the non-DHS group, none of those extensor muscles were enhanced. The enhanced pattern was butterfly shaped in 29 cases (85.3%) and linear in five cases (14.7%). All were located at the spinous process attachment at C6 or C7 in the DHS group. In the non-DHS group, seven cases presented an enhanced image of the spinous process, with C5-6 in one case, C6 in five cases, and C7 in one case. CONCLUSIONS: In DHS, contrast-enhanced MRI showed intramuscular enhancement of the cervical extensor muscles, which was not present in non-DHS cases. The enhanced muscles included the splenius capitis muscle in all cases. These findings may be useful for developing a strategy for DHS treatment.

In vivo creep and wear performance of vitamin-E-diffused highly crosslinked polyethylene in total hip arthroplasty.

INTRODUCTION: An acetabular liner thickness of around 6 mm remains the "gold standard" in total hip arthroplasty. Some surgeons have been recommending the use of the thickest possible liner because contact stress and strain in articulating surfaces decrease with increasing the wall thickness. The purpose of this study was to determine whether in vivo creep and wear performance could be enhanced using a thicker liner over the standard thickness in vitamin-E-diffused highly crosslinked polyethylene (HXLPE). MATERIALS AND METHODS: One hundred and twenty-two hips were allocated to age-matched, sex-matched, and body mass index-matched two subgroups implanted either with a 6.8- or 8.9-mm-thick vitamin-E-diffused HXLPE liner against 28-mm cobalt-chrome femoral head, and followed-up for 7 years. Linear and volumetric penetration of femoral head into the liners attributed to creep and wear were analyzed for each group. RESULTS: Compressive creep strain generated at the initial 6 months was significantly larger in the 6.8-mm group (2.6%) than in the 8.9-mm group (2.2%). The linear steady-state wear observed after 2 years was 0.0019 and 0.0015 mm/year, whereas the volumetric steady-state wear was 0.54 and 0.45 mm3/years in the 6.8- and 8.9-mm-thick groups, respectively. Although less strain in the thicker group resulted in a slightly less wear, it did not reach significant differences in the steady-state wear rates between the groups. CONCLUSION: No clinical significance for using a thicker liner over the standard thickness (6.8 mm → 8.9 mm) was confirmed in the vitamin-E-diffused HXLPE according to the 7-year follow-up. The wear rates for both thicknesses were very low enough to prevent osteolysis, and no mechanical failure was observed at any follow-up interval. Nevertheless, since the significantly higher strain was seen in the thinner liner, further follow-up is needed to compare the longer term wear and the incidence of osteolysis and component fracture.

Do polyethylene wear particles affect the development of pseudotumor in total hip arthroplasty? A minimum 15-year follow-up.

BACKGROUND: Adverse local tissue reactions have been problematic as an implant-related complication in total hip arthroplasty (THA). Despite the absence of significant metal wear and corrosion, granulomatous pseudotumor has been reported to be caused by polyethylene wear. We performed a long-term follow-up study investigating the relationship between polyethylene wear and pseudotumor formation in THA. METHODS: This study included 57 patients (64 hips) that underwent primary THA with metal-on-polyethylene or ceramic-on-polyethylene bearing over a minimum follow-up of 15 years. They were stratified into pseudotumor and non-pseudotumor groups and their linear wear rates of polyethylene liner and serum cobalt (Co) and chromium (Cr) ion levels were compared. Pseudotumor was diagnosed on metal artifact reduction sequence-MRI according to its composition and wall thickness using the Hauptfleisch classification. RESULTS: The incidence of pseudotumor was 34% (22/64 hips) at the mean follow-up of 16.9 years. Metal ion levels did not differ between the pseudotumor and non-pseudotumor groups, and none of the patients exceeded the Co/Cr ratio of 2.0 µg/L. Moreover, the wear rate in the pseudotumor group was 1.8 times greater than in the non-pseudotumor group (0.14 vs. 0.08 mm/year, P < 0.001). According to an analysis of the receiver operating characteristic curves, the cutoff level of the wear rate to discriminate between pseudotumor and non-pseudotumor patients at 15 years was 0.11 mm/year (area under the curve = 91%; sensitivity = 95%; specificity = 78%; accuracy = 87%). CONCLUSIONS: Our results might provide new insights into excessive polyethylene wear potentially leading to the future development of both pseudotumor and osteolysis. Further studies are needed to clarify the direct relationship between polyethylene wear and pseudotumor and the mutual effects of osteolysis and pseudotumor in particle reactions.

Tolerability of the first infusion of once-yearly zoledronic acid within one to two weeks after hip fracture surgery.

OBJECTIVE: Once-yearly infusions of zoledronic acid (ZA) 5 mg may be optimal for secondary fracture prevention after hip fracture (HF), but there are crucial side effects of ZA. This study assessed the tolerability of the first infusion of once-yearly ZA within one to two weeks after HF surgery and to identify risk factors for acute-phase reactions (APRs) and the decrease in serum calcium (Ca) concentration. METHODS: We analyzed 84 patients (average age: 83 years, 18 men and 66 women) who met the inclusion criteria. The patients underwent the first infusion of ZA one to two weeks after HF surgery and received antipyretic analgesics and active vitamin D analog. RESULTS: APRs occurred in ten patients (11.9%) and all these patients had pyrexia (>37.5 °C) and/or other symptoms. The asymptomatic hypocalcemia (serum Ca < 8.3 mg/dL) incidence was 6.0% at 7 days after ZA infusion. Compared with female patients without APRs, female patients with APRs had significantly higher levels of serum 25-dihydroxyvitamin D at baseline and serum C-reactive protein on the day ZA was administered (day 0). Multiple linear regression analyses showed that serum level of tartrate-resistant acid phosphatase-5b were significantly associated with an absolute decrease in serum corrected Ca from day 0 to day 7. CONCLUSIONS: The first infusion of ZA within one to two weeks after HF surgery was well tolerated with the combined use of antipyretic analgesics and active vitamin D analog. Higher inflammatory condition after surgery which is more likely sensitized by ZA administration may increase the risk of APRs, and high bone turnover may increase hypocalcemia risk.

Adverse Tissue Reactions and Metal Ion Behavior After Small-Head Metasul Hip Arthroplasty: A Long-Term Follow-Up Study.

OBJECTIVE: To investigate the long-term survivorship, incidence of adverse reactions to metal debris (ARMD), and metal ion behavior in patients who underwent small-head Metasul metal-on-metal (MoM) total hip arthroplasty (THA). METHODS: Between February 1998 and September 2003, a retrospective study was performed on 43 consecutive patients (43 hips) who underwent unilateral cementless Metasul MoM THAs at our institution. Of them, 35 patients (nine males and 26 females) who were available for follow-up more than 15 years after THA were enrolled in this study and underwent metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) to identify ARMD. The mean age at surgery of the patients was 59.7 years old (range, 31-83). Clinical and radiographic outcomes were evaluated retrospectively. Clinical examinations were conducted using the Harris Hip Score (HHS). Serum cobalt (Co) and chromium (Cr) ion levels and Co/Cr ratio were assessed at different postoperative periods of <5, 5-10, 11-14, and ≥15 years. RESULTS: The mean follow-up period for the 35 patients included was 18.1 years (range, 15-22). The mean HHS significantly improved from 44.6 ± 11.3 points preoperatively to 89.4 ± 7.9 points at the final follow-up (P < 0.0001). ARMD was found in 20% of the patients using MARS-MRI. No signs of stem loosening were found clinically or radiographically, whereas cup loosening and ARMD were observed in three patients (9%), for whom revision THAs were performed. The Kaplan-Meier survival rates with revision for any reason as the endpoint were 90.9% at 5 years, 84.8% at 10 years, 84.8% at 15 years (95% CI, 67.1-93.6), and 70.3% at 20 years (95% CI, 43.6-87.0). The survival rates with revision for ARMD as the endpoint were 100% at 5 years, 96.6% at 10 years, 96.6% at 15 years (95% CI, 77.2-99.7), and 80.1% at 20 years (95% CI, 45.3-95.2). Serum Co ion level peaked at 5-10 years after THA, which was significantly higher than that <5 years; however, it decreased to the initial level after 15 years. In contrast, serum Cr ion level significantly increased at 5-10 years and then remained almost constant. Significant differences in Cr ion levels (1.0 vs 2.0 µg/L, P = 0.024) and Co/Cr ratio (1.3 vs 0.9, P = 0.037) were found between non-ARMD and ARMD patients at >11 years postoperatively. CONCLUSION: Our results suggest that increased Cr ion levels and decreased Co/Cr ratio may be signs of ARMD in patients who underwent small-head Metasul MoM THA.

Long-term reoperation rates and causes for reoperations following lumbar microendoscopic discectomy and decompression: 10-year follow-up.

OBJECTIVE: To investigate the 10-year rates and causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS), as well as to define the reoperations at index and different lumbar levels. METHODS: Between June 2005 and May 2011, the same surgeon had been using MEDH and/or MEDS on 355 consecutive patients. The follow-up rate was 88.3%. The causes and rates of reoperations (RORs) were determined at 10 years after the initial operations. RESULTS: The 10-year reoperation rate for all patients combined was 22.1% (67/303). The 10-year reoperation rate for all cases that underwent repeat operations in the same segment was 16.5% (50/303); the most frequent reason for reoperation (FRR) was recurrence of disc herniation (ROR, 25/251 = 9.96%), the second FRR was an increase of postoperative spondylolisthesis and/or instability (ROR, 8/303 = 2.64%), and the third FRR was surgical site infection (ROR, 5/303 = 1.65%). Ten-year reoperation rate for all cases that underwent repeat operation at different lumbar levels was 5.61% (17/303); the most FRR was new disc herniation at another lumbar level (ROR, 10/303 = 3.30%), the second FRR was residual segmental stenosis (ROR, 4/303 = 1.32%), and the third FRR was new segmental stenosis at other lumbar levels (ROR, 2/303 = 0.66%). CONCLUSIONS: Three-fourths of all repeat operations were conducted in the same segment and one-fourth were performed at different lumbar levels. We believe that it is important to understand and prevent related problems.

Histopathological characteristics of cervical extensor tissue in patients with dropped head syndrome.

BACKGROUND: To date, the histopathologic characteristics of dropped head syndrome (DHS) have not been reported sufficiently. The present study investigates the histopathology of biopsy specimens from the cervical paravertebral region in patients with DHS. METHODS: Histopathological parameters were evaluated in biopsy specimens of the cervical paravertebral soft tissue from 15 patients with DHS. RESULTS: Among the 15 cases of DHS examined, skeletal muscle was identified in 7 cases, all of which showed necrosis, microvessel proliferation and atrophy. The ligament was identified in 12 cases, 8 of which showed degeneration. The lag time between the onset of symptoms and the performance of a biopsy in all 8 cases, which showed degeneration was over 3 months. Microvessel proliferation in the ligament was observed in 1 of the 4 cases, in which the lag time between the onset of symptoms and the performance of a biopsy was less than 3 months (acute or subacute phase), and in 7 of the 8 cases, in which the lag time between the symptoms and the performance of a biopsy was over 3 months (chronic phase). Chronic inflammation in the ligament was identified in 1 of the 12 cases. CONCLUSIONS: The identification of necrosis, microvessel proliferation, and atrophy in the skeletal muscle of patients with DHS and the presence of ligament degeneration and microvessel proliferation in the chronic but not acute or subacute phases may suggest that persistent skeletal muscle damage of the cervical paravertebral region causes subsequent ligament damage in patients with DHS.

The impact of sagittal imbalance on walking in patients with lumbar spinal canal stenosis.

PURPOSE: Gait and posture disorder severely impedes the quality of life of affected patients with lumbar spinal canal stenosis (LSCS). Despite the major health concern, there is a paucity of literature about the relationships among spatiotemporal gait parameters and spinal sagittal parameters. This is a cross sectional study performed in a single tertiary referral center to determine the relationships among spatiotemporal gait parameters and spinal sagittal parameters in patients with LSCS. METHODS: A total of 164 consecutive patients with LSCS, 87 men and 77 women with mean age of 70.7 years, were enrolled. Spatiotemporal gait parameters were studied using a gait analysis system. Spinal sagittal parameters were studied including sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic inclination (PI), and pelvic tilt (PT) both in the neutral and stepped positions. RESULTS: SVA was significantly larger in the stepped position than in the neutral position (neutral position, 72.5 mm; stepped position, 96.8 mm; p = 0.003). Parameters regarding the pelvis exhibited significant differences, which could represent pelvic anteversion in the stepped position. By stepwise multiple regression analysis, the prediction models, containing SVA (neutral) and PT (stepped) for double supporting phase, exhibited statistical significance, and accounted for approximately 50% of the variance. CONCLUSIONS: The present study provides statistically established evidence of correlation among spatiotemporal gait parameters and spinal sagittal parameters. Differences between sagittal parameters in neutral and stepped position may stand for the postural control during gait cycle, and increased SVA in neutral position and increased PT in stepped position may correlate with prolonged double supporting phase.

Glucose-dependent aerobic glycolysis contributes to recruiting viral components into HIV-1 particles to maintain infectivity.

The cellular environment affects optimal viral replication because viruses cannot replicate without their host cells. In particular, metabolic resources such as carbohydrates, lipids, and ATP are crucial for viral replication, which is sensitive to cellular metabolism. Intriguingly, recent studies have demonstrated that human immunodeficiency virus type 1 (HIV-1) infection induces a metabolic shift from oxidative phosphorylation to aerobic glycolysis in CD4+ T cells to produce the virus efficiently. However, the importance of aerobic glycolysis in maintaining the quality of viral components and viral infectivity has not yet been fully investigated. Here, we show that aerobic glycolysis is necessary not only to override the inhibitory effect of virion-incorporated glycolytic enzymes, but also to maintain the enzymatic activity of reverse transcriptase and the adequate packaging of envelope proteins into HIV-1 particles. To investigate the effect of metabolic remodeling on the phenotypic properties of HIV-1 produced by infected cells, we replaced glucose with galactose in the culture medium because the cells grown in galactose-containing medium are forced to carry out oxidative metabolism instead of aerobic glycolysis. We found that the packaging levels of glyceraldehyde 3-phosphate dehydrogenase, alpha-enolase and pyruvate kinase muscle type 2, which decrease HIV-1 infectivity by packaging into viral particles, are increased in progeny viruses produced by the cells grown in galactose-containing medium. Furthermore, we found that the entry and reverse transcription efficiency of the progeny viruses were reduced, which was caused by a decrease in the enzymatic activity of reverse transcriptase in the viral particles and a decrease in the packaging levels of envelope proteins and reverse transcriptase. These results indicate that the aerobic glycolysis environment in HIV-1-infected cells may contribute to the quality control of viruses.

Cervical sagittal alignment in patients with dropped head syndrome.

BACKGROUND: Dropped head syndrome (DHS) can be divided into two types, the positive sagittal vertical axis (SVA) type and the negative SVA type. However, the cervical sagittal alignment of DHS including global sagittal spinal alignment and the typical cervical alignment of the types of DHS is still unclear. The purpose of this study was to clarify the character of cervical sagittal alignment of DHS and analyze the relationship between cervical sagittal alignment and global sagittal spinal alignment. METHODS: The subjects were 35 DHS patients (10 men, 25 women, mean 71.1 years old). They were divided into two groups: negative DHS (N-DHS group, SVA < 0 mm) and positive DHS group (P-DHS group, SVA ≥ 0 mm). As control, 28 age-matched cervical spondylosis patients (CS, 21 men, 7 women, mean 67.4 years old) were analyzed. The following parameters were measured on lateral global-spine standing radiographs: cervical SVA (C2-C7SVA), O-C2A (O-C2 angle), C2 slope (C2S), C2-7A (C2-7 angle), T1 slope (T1S) and C7SVA. RESULTS: The results of measurements of each of the averaged sagittal alignment parameters were (CS, P-DHS, N-DHS): C2-7SVA(26.2 mm, 47.3 mm, 44.5 mm), O-C2 angle (35.0°, 37.1°, 39.3°), C2S (16.5°, 31.4°, 33.8°), C2-7A (9.3°, 9.9°, -16.6°), T1S (22.9°, 39.7°, 25.7°), C7SVA (35.3 mm, 51.0 mm, -43.1 mm). C2-C7SVA and C2S were significantly larger in both types of DHS compared to CS. Comparing P-DHS with N-DHS, C2-C7A and T1S were significantly smaller in N-DHS. CONCLUSIONS: O-C2A did not differ significantly among CS, P-DHS and N-DHS. In DHS patients, C2-7SVA and C2S were significantly larger than those of CS regardless of the type of DHS. The typical cervical sagittal alignment of DHS was different between P-DHS and N-DHS. In P-DHS, C2-7A and T1S were larger than those in N-DHS and the imbalance of thoraco-lumbar alignment should be noted.

Eight cases of sudden-onset dropped head syndrome: patient series.

BACKGROUND: As the proportion of elderly people continues to increase, the number of patients with dropped head syndrome (DHS) also grows. However, the relationship between onset and clinical course of DHS has hardly been studied, particularly, that of sudden-onset DHS has not been reported and remains unclear. OBSERVATIONS: Sudden-onset DHS was defined as presenting with chin on chest deformity within 3 days from the time of awareness of cervical weakness. Sixty-six patients with DHS visited our facility. Among them, 8 of the total cases (12.1%) had experienced sudden onset DHS (6 females and 2 males; average age: 71.9 ± 10.9 years). Six of 8 cases showed recovery by conservative treatment, whose first interventions were from 0.1 to 12 months, but 3 experienced recurrence. Diffuse spinal kyphotic-type DHS was seen in 2 cases, and both had recurring horizontal gaze disturbance after initial recovery. Two unimproved cases underwent surgery of combined anterior and posterior cervical fixation, and their first interventions were at 5 and 24 months. After surgery, cervical sagittal alignment was improved, and they could walk maintaining horizontal gaze. LESSONS: Sudden-onset DHS can be expected to have a better outcome, but recurrence is possible in global imbalanced-type DHS.

Does intraoperative mechanical prophylaxis prevent venous thromboembolism in total knee arthroplasty? - effectiveness of passive-assisted ankle motion in surgical/non-surgical side.

BACKGROUND: Gradual compression stocking (GCS) and intermittent pneumatic compression device (IPCD) are used for intraoperative mechanical prophylaxis against venous thromboembolism (VTE) during total knee arthroplasty (TKA). In this study, we applied a passive-assisted ankle motion in combination with GCS and IPCD during TKA and evaluated its effectiveness in preventing postoperative VTE. METHODS: We included 77 patients who underwent primary unilateral TKA. Patients were divided into group A (53 patients who underwent GCS and IPCD on their non-surgical side limb) and group B (24 patients who underwent passive ankle dorsiflexion motion in addition to GCS and IPCD on their non-surgical side limb). Deep vein thrombosis (DVT) was assessed using lower extremity ultrasonography (US). The incidence of VTE in each affected limb was compared between the two groups. RESULTS: US was performed 4 days after surgery on average. The incidence of DVT in groups A and B was 47.2 and 70.8 %, respectively. In group A, 22.6 % of DVTs were found only on the surgical side, 11.3 % on the non-surgical side, and 13.2 % on both sides. On the other hand, in group B, 41.7 % of DVTs were found only on the surgical side, 4.2 % on the non-surgical side, and 25.0 % on both sides. No significant difference in the incidence of VTE was noted between the 2 groups. CONCLUSIONS: The intraoperative application of passive ankle motion plus GCS and IPCD might not further reduce the incidence of postoperative DVT in TKA patients.

Impact of surgical clothing and footwear on operating room contamination during standstill and intraoperative stepping motion.

BACKGROUND: In view of preventing surgical site infection (SSI) in the orthopedic operating room (OR), evidence concerning types of footwear and clothing is limited. This study aimed to investigate how different footwear and clothing affect the cleanliness of the OR environment. METHODS: The airborne dust concentration in a bioclean room (NASA class 100) was measured around an operator by using a handheld particle counter under the following conditions: (I) wearing a sterilized full-type space suit with OR dedicated clean sandals; (II) wearing a sterilized full-type space suit with non-dedicated (outside) shoes or severely contaminated outside shoes with surgical glove powder (2 µm mean particle size); and (III) wearing an unsterilized medical scrub uniform with OR dedicated sandals. The participant was standing still or stepping in place at 1 Hz during the testing. RESULTS: The concentrations of airborne dusts in the operative field were independent of footwear and clothing types under the stand-still condition. However, these values significantly increased 1.96- to 16.23-fold after simple stepping motion in all the test conditions, and often became dissatisfaction level with the NASA100 requirement for the OR cleanliness. The worst contamination occurred when an operator wore the powder-contaminated shoes and also the unsterilized scrub uniform. CONCLUSION: The present study showed that the stepping motion triggered a considerable contamination in the operative field (beyond the level of NASA100 threshold) particularly when an operator used the outside shoes or unsterilized scrub uniform. Therefore, these results tell us that the one-footwear system (i.e., no use of OR dedicated clean shoes) and unsterilized scrub are likely to be a potential risk factor for SSI. Nevertheless, further studies are necessary to conclude the real efficacy of OR dedicated shoes and sterilized clothes on the SSI prevention.

Risk factors of dysphagia in patients with ossification of the anterior longitudinal ligament.

INTRODUCTION: Cervical ossification of the anterior longitudinal ligament (OALL) occasionally leads to dysphagia by the anterior osteophyte. A recent report explained that the dysphagia after an occipito-cervical fusion is caused by the narrowing of pharyngeal space due to the cranio-cervical malalignment. The purpose of this study was to evaluate the cranio-cervical alignment in patients with OALL complaining of the dysphagia. SUBJECTS AND METHODS: The subjects were 11 cases with complaining of dysphagia due to cervical OALL who underwent anterior cervical OALL resection and as control, age-matched 12 cases without dysphagia who have diffuse idiopathic skeletal hyperostosis in cervical spine. All subjects were male, and the mean age was 59.5 ± 9.1 years. The subjects were divided into two groups according to the symptoms of dysphagia (dysphagia, group A; control, group B). The O-C2 angle, C2-C7 angle, and the maximum thickness of OALL and the cranio-cervical alignment (pharyngeal inlet angle; PIA) and swallowing line (S-line) were measured before and after the operation on the lateral cervical radiogram at the sitting position. RESULTS: Group A showed significantly large maximum thickness of OALL, small cervical range of motion, small O-C2 angle, large C2-C7 angle, and small PIA. The S-line crossed the anterior apex of cervical osteophyte in group A. After OALL resection, dysphagia had improved, PIA had increased, and the S-line uncrossed the apex of cervical vertebrae in all cases. CONCLUSION: The prevalence of dysphagia in patients with cervical OALL was influenced by the thickness of osteophyte, cervical mobility, and cranio-cervical alignment.

Alpha-enolase in viral target cells suppresses the human immunodeficiency virus type 1 integration.

BACKGROUND: A protein exhibiting more than one biochemical function is termed a moonlighting protein. Glycolytic enzymes are typical moonlighting proteins, and these enzymes control the infection of various viruses. Previously, we reported that glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and alpha-enolase (ENO1) are incorporated into human immunodeficiency virus type 1 (HIV-1) particles from viral producer cells and suppress viral reverse transcription independently each other. However, it remains unclear whether these proteins expressed in viral target cells affect the early phase of HIV-1 replication. RESULTS: Here we show that the GAPDH expression level in viral target cells does not affect the early phase of HIV-1 replication, but ENO1 has a capacity to suppress viral integration in viral target cells. In contrast to GAPDH, suppression of ENO1 expression by RNA interference in the target cells increased viral infectivity, but had no effect on the expression levels of the HIV-1 receptors CD4, CCR5 and CXCR4 and on the level of HIV-1 entry. Quantitative analysis of HIV-1 reverse transcription products showed that the number of copies of the late products (R/gag) and two-long-terminal-repeat circular forms of viral cDNAs did not change but that of the integrated (Alu-gag) form increased. In contrast, overexpression of ENO1 in viral target cells decreased viral infectivity owing to the low viral integration efficiency. Results of subcellular fractionation experiments suggest that the HIV integration at the nucleus was negatively regulated by ENO1 localized in the nucleus. In addition, the overexpression of ENO1 in both viral producer cells and target cells most markedly suppressed the viral replication. CONCLUSIONS: These results indicate that ENO1 in the viral target cells prevents HIV-1 integration. Importantly, ENO1, but not GAPDH, has the bifunctional inhibitory activity against HIV-1 replication. The results provide and new insights into the function of ENO1 as a moonlighting protein in HIV-1 infection.

Global sagittal spinal alignment at cervical flexion in patients with dropped head syndrome.

PURPOSE: Dropped head syndrome (DHS) is characterized by the passively correctable chin-on-chest deformity. The characteristic feature is emphasized in the cervical flexion position. The purpose of this study was to analyze the influence of cervical flexion on sagittal spinal alignment in patients with DHS. METHODS: The study included 15 DHS subjects and 55 cervical spondylosis (CS) subjects as the control group. The following parameters were analyzed: cervical sagittal vertical axis (C-SVA), occipitoaxial angle (O-C2A), C2 slope (C2S), C2-C7 angle (C2-C7A), T1 slope (T1S), sagittal vertical axis, T1-T4 angle (T1-T4A), T5-T8 angle (T5-T8A), T9-T12 angle, lumbar lordosis, sacral slope, and pelvic tilt, in cervical flexion and neutral positions. RESULTS: The values of C-SVA, O-C2A, C2S, and T1S were significantly different between CS and DHS at cervical neutral and flexion positions. C2-C7A showed significant difference in cervical neutral position, but the difference disappeared in flexion position. T1-T4A did not present a significant difference, but T5-T8A showed a difference in neutral and flexion positions. CONCLUSIONS: Malalignment of DHS extended not only to cervical spine but also to cranio-cervical junction and thoracic spine, except T1-T4. It is known that global sagittal spinal alignment is correlated with adjacent parameters, although in DHS the reciprocal change was lost from cranio-cervical junction to the middle part of thoracic spine at cervical flexion.

Do Polyethylene Supra-Macroparticles Lead to Pseudotumor Formation in Metal-on-Polyethylene Total Hip Arthroplasty?

We describe 2 cases of pseudotumors induced by an unusual size of polyethylene wear particle after metal-on-polyethylene total hip arthroplasty (MoP THA). The supra-macroparticles of size >100 µm originated from a polyethylene liner with relatively small cup anteversion, potentially leading to excessive loading and increased wear of the anterior edge of the polyethylene liner. Histopathology showed a foreign-body reaction to the polyethylene particles without an adverse reaction to metal debris and with no severe signs of corrosion at the head-neck junction, which have been noted in past reports of pseudotumors in MoP THA. It has been suggested that the large polyethylene wear particles might be the cause of pseudotumor formation in MoP THA.

Mode of onset of dropped head syndrome and efficacy of conservative treatment.

PURPOSE: The initial treatment of dropped head syndrome (DHS) is basically nonsurgical, but the mode of onset of DHS and efficacy of conservative treatment have not been fully clarified. METHODS: The subjects were 38 DHS patients without neuromuscular disease (11 men and 27 women, average age 74.5 years). Cervical collar, physical therapy, and temporary medication for cervical pain were provided for all DHS patients. The following parameters were measured on lateral global spine standing radiographs: sagittal vertical axis (SVA), cervical sagittal vertical axis, C2-C7 angle, first thoracic slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. According to the mode of onset of DHS, the subjects were classified into acute-onset group (<3 months) and chronic-onset group (≥3 months). RESULTS: Acute- and chronic-onset DHS were observed in 20 and 18 patients, respectively. A history of cervical trauma was involved in nine and two cases of acute- and chronic-onset DHS, respectively. Acute-onset DHS included more balanced-SVA (B-SVA: -30 mm

Does artificial aging correctly predict the long-term in-vivo degradation behavior in zirconia hip prostheses?

BACKGROUND: Accelerated hydrothermal aging has long been one of the most widely accepted quality control tests for simulating low-temperature degradation (LTD) in zirconia-containing implants used in total hip arthroplasty (THA). However, it is still unclear how much consistency there is between the experimental prediction from the internationally-standardized tests and the actual measurements from surgically-removed implants after a long period of implantation. This question is fundamentally related to a lack of understanding of mechanical/tribological contribution to the in-vivo LTD kinetics. OBJECTIVE: The main purpose of this study is to validate the clinical relevance of standardized accelerated aging by comparing artificially-aged and in-vivo used prostheses, and to clarify the long-term effects of in-vivo mechanics/tribology on the LTD progression upon service in the body environment. METHODS: Surface magnitudes of phase transformation and residual stress in zirconia femoral head retrievals (13.1-18.4 yrs) were evaluated by using confocal Raman microspectroscopy. RESULTS: The long-term aging behavior in unworn head surface was in agreement with the experimental prediction estimated as 1 h aging at 134 °C = 4 years in-vivo. However, the current aging protocols based on ASTM and ISO criteria were not accurately predictive for the worn surfaces, and the tribologically-induced phase transformation and tensile stress were up to 6.5-times and 3.3-times higher than the environmentally-induced ones. CONCLUSION: Our study suggests that wear/scratching, frictional heating, tribochemical reactions, and metal transfer may become far more intense triggers to phase transformation than the mere exposure to body fluid.

Pelvic tilt after total hip arthroplasty in patients with osteoarthritis of the hip.

BACKGROUND: It is important to understand postoperative global sagittal spinal alignment after total hip arthroplasty (THA) to prevent not only the following hip complications but also progressing lumbar degeneration. The purpose of this study was to progress the analysis of the global sagittal spinal alignment between before and after THA in patients without large lower limbs discrepancy. SUBJECTS AND METHODS: The subjects were 87 patients with bilateral hip osteoarthritis (OA) before unilateral primary THA. We measured sagittal vertical axis (SVA), lumbar lordotic angle, sacral slope, pelvic tilt (PT), and pelvic incidence (PI) and compared the postoperative change of those parameters. Excluded criteria were Crowe classification types II, III, and IV and more than 10 mm of leg length difference, spinal scoliosis (Cobb angle > 25°), and lumbar kyphosis. RESULTS: The correlation coefficient between preoperative factors and postoperative sagittal alignments revealed that postoperative SVA has correlation with age (r = 0.46, p < 0.008) and preoperative PT (r = 0.42, p = 0.015). Postoperative PT had a correlation with preoperative PI (r = 0.46, p = 0.007). The change of PT after operation had negative correlation to preoperative PT (r = -0.47, p < 0.01) and PI (r = -0.38, p = 0.03). Multiple regression analysis revealed that the change of PT = 4.979 - 0.235 × preoperative PT (p < 0.05). Therefore, when preoperative PT was less than 20°, the postoperative PT would become larger than the preoperative one. CONCLUSION: (1) In patient with hip OA without large lower limbs discrepancy, the postoperative PT after THA correlated with PI. (2) The postoperative change of PT was influenced by preoperative PT.