微创经椎间孔腰椎体间融合术与传统开放手术对退变性腰椎滑脱症腰椎-骨盆矢状位参数的不同影响

【摘要】 目的：比较微创经椎间孔腰椎体间融合术（transforaminal lumbar interbody fusion,TLIF）与传统开放后路腰椎体间融合术（posterior lumbar interbody fusion,PLIF）治疗退变性腰椎滑脱症对腰椎-骨盆矢状位参数的不同影响。方法：回顾性分析比较2010年6月~2013年6月符合纳入标准的L4单节段退变性腰椎滑脱症48例患者的临床资料,其中23例采用传统开放PLIF治疗（开放组）,25例采用微创Quadrant系统下TLIF治疗（微创组）。在包含双侧股骨头的站立位腰椎侧位X线片上,测量微创组与开放组术前及末次随访的滑脱度（SP）、腰椎前凸角（LL）、骨盆入射角（PI）、骨盆倾斜角（PT）、骶骨倾斜角（SS）、腰骶角（LSA）、滑脱角（SA）及L1铅垂线与S1距离（LASD）参数变化,采用相关分析分析各参数间的相关性。结果：开放组的滑脱复位率（ΔSP）为（67.42±33.80）%,明显高于微创组的（36.59±50.68）%（P<0.05）。微创组末次随访时的LL为43.03°±14.07°、SA为3.12°±4.02°,均明显低于术前的46.53°±15.72°、6.10°±5.64°（P<0.05）。开放组的ΔSA为2.53°±6.63°,明显高于微创组的-2.98°±5.42°（P<0.05）。开放组的ΔLASD为-4.10±14.53mm,明显低于微创组的3.48±9.01mm（P<0.05）。术前SP与LASD、ΔSA与ΔLL具有正相关关系,ΔLL与ΔPT具有负相关关系。结论：对于退变性腰椎滑脱,微创TLIF和开放PLIF都能明显地使滑脱椎体复位,但开放PLIF的滑脱复位率较高。微创TLIF可明显减小LL、SA,导致融合节段相对后凸。开放PLIF可明显减小LASD,更有助于改善脊柱-骨盆矢状位力线平衡。     

DIAMUND: Direct Comparison of Genomes to Detect Mutations

DNA sequencing has become a powerful method to discover the genetic basis of disease. Standard, widely used protocols for analysis usually begin by comparing each individual to the human reference genome. When applied to a set of related individuals, this approach reveals millions of differences, most of which are shared among the individuals and unrelated to the disease being investigated. We have developed a novel algorithm for variant detection, one that compares DNA sequences directly to one another, without aligning them to the reference genome. When used to find de novo mutations in exome sequences from family trios, or to compare normal and diseased samples from the same individual, the new method, direct alignment for mutation discovery (DIAMUND), produces a dramatically smaller list of candidate mutations than previous methods, without losing sensitivity to detect the true cause of a genetic disease. We demonstrate our results on several example cases, including two family trios in which it correctly found the disease‐causing variant while excluding thousands of harmless variants that standard methods had identified.     

Can pelvic tilting be ignored in total hip arthroplasty?

INTRODUCTION

The orientation of acetabular component is influenced by pelvic tilt, body position and individual variation in pelvic parameters. Most post-operative adverse events may be attributed to malposition of the component in the functional position. There is evidence that orientation of the pelvis changes from the supine to standing position. Authors report a case of recurrent dislocation after total hip arthroplasty due to excessive pelvic tilting.PRESENTATION OF CASE A 69-year old female with coxarthrosis had undergone total hip replacement with recurrent dislocation of the hip on bearing weight in spite of using constrained acetabular component.

DISCUSSION

Our case report substantiates the influence of pelvic tilt, incurred by a sagittal deformity of spine, on dynamic orientation of the acetabular cup which was positioned in accordance with the anatomic landmarks alone. If the reference is only bony architecture and dynamic positions of the pelvis are not taken into account, improper functional orientation of the acetabular cup can result in sitting and standing positions. These can induce instability even in anatomically appropriately oriented acetabular component.

CONCLUSION

The sagittal position of pelvis is a key factor in impingement and dislocation after total hip arthroplasty. Pelvic tilting affects the position of acetabular component in the sagittal plane of the body as compared with its anatomic position in the pelvis. We suggest a preoperative lateral view of spine-pelvis, in upright and supine position for evaluation of a corrective adaptation of the acetabular cup accordingly with pelvic balance.     

Anterior thoracic posture increases thoracolumbar disc loading

In the absence of external forces, the largest contributor to intervertebral disc (IVD) loads and stresses is trunk muscular activity. The relationship between trunk posture, spine geometry, extensor muscle activity, and the loads and stresses acting on the IVD is not well understood. The objective of this study was to characterize changes in thoracolumbar disc loads and extensor muscle forces following anterior translation of the thoracic spine in the upright posture. Vertebral body geometries (C2 to S1) and the location of the femoral head and acetabulum centroids were obtained by digitizing lateral, full-spine radiographs of 13 men and five women volunteers without previous history of back pain. Two standing, lateral, full-spine radiographic views were obtained for each subject: a neutral-posture lateral radiograph and a radiograph during anterior translation of the thorax relative to the pelvis (while keeping T1 aligned over T12). Extensor muscle loads, and compression and shear stresses acting on the IVDs, were calculated for each posture using a previously validated biomechanical model. Comparing vertebral centroids for the neutral posture to the anterior posture, subjects were able to anterior translate +101.5 mm±33.0 mm (C7–hip axis), +81.5 mm±39.2 mm (C7–S1) (vertebral centroid of C7 compared with a vertical line through the vertebral centroid of S1), and +58.9 mm±19.1 mm (T12–S1). In the anterior translated posture, disc loads and stresses were significantly increased for all levels below T9. Increases in IVD compressive loads and shear loads, and the corresponding stresses, were most marked at the L5–S1 level and L3–L4 level, respectively. The extensor muscle loads required to maintain static equilibrium in the upright posture increased from 147.2 N (mean, neutral posture) to 667.1 N (mean, translated posture) at L5–S1. Compressive loads on the anterior and posterior L5–S1 disc nearly doubled in the anterior translated posture. Anterior translation of the thorax resulted in significantly increased loads and stresses acting on the thoracolumbar spine. This posture is common in lumbar spinal disorders and could contribute to lumbar disc pathologies, progression of L5–S1 spondylolisthesis deformities, and poor outcomes after lumbar spine surgery. In conclusion, anterior trunk translation in the standing subject increases extensor muscle activity and loads and stresses acting on the intervertebral disc in the lower thoracic and lumbar regions.This study was presented, in part, at the 29th annual meeting of the International Society for the Study of the Lumbar Spine, Cleveland, OH, USA, 2002 May 14–18     

Improved accuracy of navigated drilling using a drill alignment device.

Drilling procedures are common in orthopedic surgery and are one specific task that may be aided by computer-assisted navigation. However, the inherent flexibility of drill bit bending may make this the limiting factor in achieving acceptable accuracy when using these systems. We designed an alignment device that was fit to a standard orthopedic drill that allowed an extension of the stabilizing point of a drill bit. In foam blocks with a similar density as cancellous bone, 208 total navigated drilling trials were performed, using four different sized drill bits (2.5, 3.2, 3.5, and 4.5 mm) with and without the alignment device. Drilling tracts of 80 mm were made towards an intended target on the other side of the block. Reduction in deviation from the intended target was significantly improved with the use of the guide, ranging from 33% to 45% for the four drill sizes. For the trails using the alignment device, the 2.5-mm drill bit was significantly less accurate than the three larger drills. Our results demonstrate that the use of external devices to augment drill bit stabilization can improve drilling accuracy. This may have particular importance when using navigation systems to drill into small anatomic confines.     

Non-invasive phakometric measurement of corneal and crystalline lens alignment in human eyes

We describe a non-invasive phakometric method for determining corneal axis rotation relative to the visual axis (beta) together with crystalline lens axis tilt (alpha) and decentration (d) relative to the corneal axis. This does not require corneal contact A-scan ultrasonography for the measurement of intraocular surface separations. Theoretical inherent errors of the method, evaluated by ray tracing through schematic eyes incorporating the full range of human ocular component variations, were found to be larger than the measurement errors (beta < 0.67 degrees , alpha < 0.72 degrees and d < 0.08 mm) observed in nine human eyes with known ocular component dimensions. Intersubject variations (mean +/- S.D.: beta = 6.2 +/- 3.4 degrees temporal, alpha = 0.2 +/- 1.8 degrees temporal and d = 0.1 +/- 0.1 mm temporal) and repeatability (1.96 x S.D. of difference between repeat readings: beta +/- 2.0 degrees , alpha +/- 1.8 degrees and d +/- 0.2 mm) were studied by measuring the left eyes of 45 subjects (aged 18-42 years, 29 females and 16 males, 15 Caucasians, 29 Indian Asians, one African, refractive error range -7.25 to +1.25 D mean spherical equivalent) on two occasions.     

Analysis of sagittal curvature and its influencing factors in adolescent idiopathic scoliosis

This study aimed to explore the characteristics of changes in the sagittal arrangement of the spine between adolescent patients with idiopathic scoliosis (AIS) and normal adolescents, the risk factors for AIS and the factors affecting the progress of AIS.X-ray images of the full length of the spine in standing position were taken in AIS patients and normal adolescents. Radiographic measurements made at intermediate follow-up included the following:C₁ and C₂ cervical lordosis and C₂ - C₇ curvature of cervical lordosis, C₂-C₇sagittal horizontal distance (C₂-C₇SagittalVerticalAxis, C₂-C₇SVA), TS-CL, after thoracic lobe (Thoracic Kyphosis, TK), thoracic lumbar segment Angle (thoracolumbar kyphosis, [TLK]), lumbar lordosis Angle (Lumbar Lordosis, LL), sacral slope Angle (Sacrum Slope, SS), pelvic tilt Angle (Pelvic Tilt, PT), pelvic incidence (PI), L₅ Incidence (Lumbar5 Slope (L₅S), L5 incidence (Lumbar5 Incidence (L₅I), sagittal horizontal distance (_CSVA), lower depression Angle of the 2nd cervical spine. The difference of sagittal plane parameters between AIS group and normal adolescent group was compared. To evaluate the progress of AIS, correlation analysis was conducted between diagonal 2 and other parameters. The main risk factors of AIS were determined by binary Logistic analysis.The _CSVA of AIS patients was higher than that of healthy adolescents (AIS: 27.64 ± 19.56) mm. Healthy adolescents: (17.74 ± 12.8) mm), L5S (AIS: 19.93°= 7.07° and healthy adolescents: 15.38°= 7.78°, P = .024 < .05), C₂ downward sag Angle (AIS: 15.12°= 2.7°;Healthy adolescents: 12.97°= 4.56°); AIS patients had lower TS-CL (AIS: 22.48 ± 6.09 and healthy adolescents: 28.26°= 10.32°), PT (AIS: 10.42°= 4.53° and healthy adolescents: 15.80°=7.68°), (AIS: 41.87°=9.72° and healthy adolescents: 48.75°= 8.22°). The main risk factor for idiopathic scoliosis in adolescents was L₅ (OR = 1.239, 95%CI = 1.049–1.463, P = .012 < .05).L₅S is a major risk factor for idiopathic scoliosis in adolescents. The larger PI is, the higher the risk of scoliosis progression is. In AIS patients, lumbar lordosis is increased, cervical lordosis is reduced, and even cervical kyphosis occurs.     

双侧下颌升支矢状劈开截骨术后稳定性的研究

目的:主要探讨BSSRO后退下颌骨术后骨的稳定性,了解导致复发的有关因素。方法:46例单纯下颌前突患者,不包括存在偏颌畸形的病例。所有患者于手术前一周(T1)、术后一周(T2)、术后6个月或6个月以上(T3)分别拍摄头颅定位侧位片,测量硬组织的相对位移。结果:BSSRO后退下颌骨后,使得硬组织Li点平均后退了6.5mm,B点平均后退了7.3mm,Pg点是8.5mm,Me点为9.1mm。各标志点的平均复发率为:Li点复发率为23.1%、B点复发率为24.7%、Pg点复发率为25.9%、Me点复发率为26.4%。结论:影响下颌升支矢状劈开截骨后退术后复发的因素很多,其中受髁状突的影响使得下颌骨在向前复发的过程中并不是完全的水平复发,而是水平逆时针旋转复发。复发可能与后退量存在相关关系,但需要超过一定的后退量。