经皮椎体后凸成形术治疗严重骨质疏松性椎体压缩性骨折

目的 探讨经皮椎体后凸成形术治疗严重骨质疏松性椎体压缩性骨折的疗效。方法 2014年1月至2015年1月应用经皮椎体后凸成形术治疗严重骨质疏松性椎体压缩性骨折42例,分析手术前后Cobb's角、疼痛视觉模拟量表（VAS）评分、Oswestry功能障碍指数及骨折椎体高度变化。结果 术后椎体三柱高度显著大于术前（P<0.05）,而术后Cobb's角、VAS评分、Oswestry功能障碍指数均显著低于术前（P<0.05）。结论 经皮椎体后凸成形术治疗严重骨质疏松性椎体压缩性骨折,可以明显改善患者疼痛症状,恢复椎体高度,矫正后凸角度,有着较好的疗效。     

球囊扩张椎体后凸成形术治疗椎体压缩性骨折

随着人口的老龄化,骨质疏松症的发生率日渐增加。椎体压缩性骨折是骨质疏松症的主要并发症之一,由此引起难以忍受的背痛病例也呈上升趋势。服用药物、佩戴支具等姑息治疗效果不确切,且长期卧床会导致骨质进一步丢失,形成恶性循环;传统外科手术治疗创伤大,老年患者往往难以接受。1984年Galibert首先采用X线透视下,经皮穿刺椎体内注射骨水泥治疗侵袭性血管瘤取得满意效果。1994年Reiley在此基础上设计了通过球囊扩张来纠正后凸畸形的技术,     

经皮椎体成形术治疗伴裂缝的椎体压缩性骨折

目的探讨应用经皮椎体成形术治疗伴裂缝的椎体压缩性骨折的技术及疗效,并总结分析压缩骨折中裂缝产生的原因及治疗方法。方法16例伴裂缝的椎体压缩性骨折患者术前均行X线平片、CT检查。X线平片或透视下可见裂缝的5例(组1),其中3例为仅在注射骨水泥时发现新出现的裂缝;术前仅CT可见裂缝的11例(组2)。所有患者均行6点疼痛评分及运动能力评分。组1中患者的平均疼痛评分为(4.45±0.47)分,运动能力评分(4.66±0.43)分;组2中患者的平均疼痛评分为(4.07±0.52)分,运动能力评分为(4.45±0.49)分。16例患者中6例有明确的外伤史,5例有轻微的外伤史,余5例没有明确的外伤史。所有患者均行活检,病理报告均为变性或坏死的骨组织。结果16例手术都获得成功,注射骨水泥3～7ml,14例疼痛完全缓解,2例明显缓解。术后2d重新进行疼痛及运动能力评分,组1的平均疼痛评分为(0.41±0.57)分,运动功能评分为(1.43±0.45)分;组2的平均疼痛评分为(0.47±0.41)分,运动功能评分为(1.56±0.39)分;配对t检验术前、术后有明显差异(P<0.01)。全部病例中共有2例骨水泥渗漏到椎间盘,没有骨水泥渗漏到椎体周围组织。术后随访1～9个月,无复发迹象,影像学检查提示骨水泥和椎体稳定。结论伴裂缝的椎体压缩性骨折是经皮椎体成形术的明确的适应证。椎体压缩性骨折一旦发现裂缝,尽早行经皮椎体成形术治疗可取得良好的疗效。     

椎体成形术治疗症状性颈椎血管瘤2例

病历资料例1，女。34岁，因有上肢麻木无力伴颈部疼痛进行性加重6个月入院。CT示C6椎体内血窦扩张，呈蜂窝状改变，MRI示T1W、T2W高信号影像。诊断为C6椎体血管瘤。行右侧颈前外侧入路C6椎体成型术，将骨水泥均匀注入整个椎体。术后病理确诊为椎体血管瘤，半年后复查CT，示骨水泥完全栓塞椎体内的血管瘤病灶．病人症状完全消失。     

骨水泥注入椎体后壁破损型骨质疏松性椎体压缩性骨折椎体成形12例

中山市人民医院骨科于2005-01/2008-09应用CT引导下椎体成形治疗椎体后壁破损型骨质疏松性椎体压缩性骨折患者12例,男4例,女8例,骨折部位T10~L5,其中单椎体骨折8例,两椎体骨折3例,三椎体骨折1例,椎体均压缩1/2以上。手术均顺利完成,无椎管内骨水泥渗漏,平均手术时间45 min。提示在CT引导下对椎体后壁破损型骨质疏松性椎体压缩性骨折行椎体成形术可有效降低骨水泥的渗漏率,提高安全性。     

经皮穿刺椎体成形术治疗骨质疏松脊椎压缩性骨折的护理体会

经皮穿刺椎体成形术是治疗老年骨质疏松脊椎压缩性骨折的一种新技术，具有创伤小、恢复快、住院日短、并发症少等优点。近年来越来越被老年患者所接受。我院通过对16例手术患者的护理。取得了较为满意的临床效果，现报告如下。     

椎体后凸成形与椎体成形修复重建胸腰压缩性骨折患者脊柱稳定性的系统评价和Meta分析

目的：利用Meta分析方法对国内应用椎体后凸成形与椎体成形修复重建胸腰压缩性骨折的对照试验进行荟萃分析，从而在较大样本量的前提下评价并比较两种方法修复胸腰压缩性骨折的有效性和安全性。 方法：收集中国期刊全文数据库(1998/2008)、中国生物医学数据库及维普期刊网关于椎体后凸成形术与椎体成形术治疗胸腰压缩性骨折的对照文献，对结果进行Meta分析。其中，试验组行椎体后凸成形术，对照组行椎体成形术。疗效及差异评价指标以比值比、加权均数差和95%可信区间(CI)表示。统计学分析采用Review Manager4.2软件。 结果：共收集国内8个随机对照研究，Meta分析结果显示，2组病例术后目测类比疼痛评分均降低，但差异无显著性意义[比值比为-0.07，95%CI(-0.35，-0.49)，P=0.75]。2组病例手术前后Cobb角均下降，但试验组较对照组下降更明显 [比值比为-8.60，95%CI(-13.36，-3.83)，P=0.0004]。2组病例手术前后椎体前缘平均高度恢复率均升高, 但试验组较对照组升高更明显[比值比为25.08，95% CI(9.30，40.87)，P=0.002)。2组病例手术前后椎体压缩率均降低，但试验组降低更明显[比值比为-12.04，95%CI(-17.03，-7.04)，P < 0.000 01]。 结论：与椎体成形术相比，椎体后凸成形术修复重建胸腰压缩性骨折能够更好地缩小Cobb角，降低椎体压缩率，同时椎体前缘平均高度得以更好的恢复，但两者在缓解术后疼痛方面无明显差异。     

经皮椎体成形和经皮椎体后凸成形治疗国人胸腰椎压缩性骨折疗效及安全性的Meta分析

背景：经皮椎体成形和经皮椎体后凸成形治疗胸腰椎压缩性骨折在国内外均积累了相当多的临床经验,但尚缺乏循证医学方面的依据。目的：采用Meta分析评价经皮椎体成形和经皮椎体后凸成形治疗胸腰椎压缩性骨折的疗效以及安全性。方法：搜集国内应用经皮椎体成形和经皮椎体后凸成形对比治疗胸腰椎压缩性骨折的文献,并追查已纳入文献的参考文献。由至少两位系统评价员做独立文献筛查、质量评价和资料提取,并交叉核对,不同意见请第三者裁决。使用统计软件RevMan 5.0完成Meta分析。结果与结论：经筛选,最后纳入7篇文献进行Meta分析,包括受试患者398例,其基线情况一致,具有可比性。5篇文献的随访时间为6周,2篇为4周。结果提示,经皮椎体成形和经皮椎体后凸成形均是治疗国人胸腰椎压缩性骨折的有效方法,且在改善目测类比评分方面差异无显著性意义(P > 0.05);在改善Cobb角及治疗后骨水泥渗漏发生率方面,经皮椎体后凸成形均优于经皮椎体成形(P < 0.001,P=0.05)。因纳入文献和样本量有限,建议进行大样本、长期随访的高质量临床试验,提供更佳循证证据。     

经皮椎体成形术在椎体压缩骨折及椎体肿瘤治疗中的临床应用

目的 总结分析经皮椎体成形术(PVP)在骨质疏松性椎体压缩骨折及椎体肿瘤治疗中临床应用的疗效.方法 宣武医院神经外科2007年1月至2012年6月应用PVP治疗45例患者共62个病变椎体,随访时间点为术后24h、3、6、12、24及36个月,采用VAS、ODI评价其临床疗效,椎体前缘高度及Cobb角评估影像学结果.结果 平均随访时间(13.9±7.8)个月,术后24 h,患者VAS疼痛评分、ODI指数及Cobb角分别由术前(7.3±1.9)分、32.0±3.4和15.0°±2.3°降至术后(4.8±1.6)分、22.1±2.1和14.0°±1.9°(P＜0.05),椎体前缘高度由术前(16.0±1.8) mm升至(19.0±2.1)mm(P＜0.05).3～36个月随访期内,VAS评分、椎体前缘高度及Cobb角差异无统计学意义(P＞0.05).随访中约54％患者VAS评分维持在5分以内.结论 PVP是治疗骨折及肿瘤所致的椎体源性疼痛简单有效的微创疗法,临床疗效稳定.     

102例经皮椎体成形术22例骨水泥渗漏原因分析及防治

老年人骨质疏松所致的椎体压缩性骨折（VCF）可致伤椎椎体塌陷,脊柱稳定性下降,疼痛和神经功能丧失。传统的治疗方法采用长期卧床休养等治疗,患者生活质量严重下降,且易出现坠积性肺炎、下肢深静脉血栓,褥疮等并发症,尤其对高龄,基础疾病较多者;有的学者尝试使用开放手术,然而对于老年VCF患者特别是高龄患者,骨质对内固定物的把持力不够,容易出现内固定在椎体内的切割,松动现象,导致内固定物松动,拔出致治疗失败。1984年首次应用经皮椎体成形术治疗椎体血管瘤,1997年开始采用经皮椎体成形术(Percutancousvertebroplasty,PVP)成功治疗老年VCF。该方法为微创性手术,早期止痛效果好,术后患者可早期下地活动,避免了患者长期卧床引起的各种并发症,目前在国内外得到了广泛的应用,但不可忽视的是PVP术由于骨水泥自身具有一定流动性性状所致的渗漏比例较高,大量临床资料显示这种渗漏多不至造成严重神经血管症状,如致死性大出血,不可逆性脊髓,外周神经损伤,但由于骨水泥在凝固过程中于局部释放大量热量,最高可达80C°-90C°,且渗漏后的固体骨水泥块位移及定位位置具有一定随机性,不可控性,如占位于关键点部位,如椎管内,神经根孔等处,仍有一定机率出现严重,不可逆性后果,如截瘫等,如何在临床工作中尽量减少骨水泥渗漏机率,减轻骨水泥渗漏后造成的影响,有必要从PVP术手术适应症,具体操作细节等方面做深入探讨。目的：探讨经皮椎体成形术(Percutaneous vertebroplasty,PVP)骨水泥渗漏的防治措施。方法：经皮椎体成形术治疗VCF102例131个椎体,方法再完善一些患者俯卧位或侧卧位,在X线机透视下定位伤椎,选定穿刺点,经单侧椎弓根至椎体前中1／3处,透视下注入并观察骨水泥PMMA填充、弥散情况,至填充、弥散满意后3～5 min,拔出穿刺针,24 h后鼓励患者下地活动。观察术后疼痛缓解情况及术后1月一般健康状况,手术疗效及骨水泥渗漏情况,。。结果与结论：所有患者术后疼痛即明显缓解,术前术后VAS疼痛评分分别为(8.78±0.58)分、(1.13±0.34)分,术前术后VAS分值具有明显差异(P<0.05),术后半年和术后一年VAS疼痛评分分别为(1.12±0.32)分、(1.55±0.50)分,VAS分值差异无统计学意义(P>0.05)。术前术后SF-36生活质量积分比较(mean±SD),PVP术后患者疼痛改善状况,总体健康,活力完成社会职能方面与术前比较有差异有统计学意义,术后优于术前。骨水泥渗漏22例：渗漏至椎管1例,改行开放手术后患者恢复良好;渗漏至神经根管3例,经保守治疗后缓解;渗漏至椎间隙内10例,椎旁8例,无明显临床症状。聚甲基丙烯酸骨水泥（PMMA）与成人骨成分一致,组织相容性好,即使长期留置体内也不会有排斥反应,PVP治疗VCF效果良好,但是骨水泥渗漏发生率较高,需严格掌握手术适应证,减少骨水泥渗漏的发生。     

Safety and therapeutic efficacy of the second treatment for new fractures developed after initial vertebroplasty performed for painful vertebral compression fractures

Abstract

Objectives: There is no report on the safety and therapeutic efficacy of the second treatment for new vertebral fractures developed after vertebroplasty. This study aims to examine the therapeutic effects and clinical characteristics in patients undergoing a second vertebroplasty for these new fractures.

Methods: The initial treatment group included 182 patients (276 vertebrae) who underwent vertebroplasty. Among 182 patients, the second treatment group included 34 patients (36 vertebrae) who developed new fractures postoperatively, which were retreated. Analgesic effects on the day following surgery, frequency of new fractures during the 12 month period after surgery, and other clinical characteristics were compared between the initial and second treatment groups. Furthermore, similar comparisons were performed between patients with adjacent and non-adjacent vertebral fractures in the second treatment group.

Results: The improvement rates in visual analogue scale (VAS) scores before and after surgery were 83·4% in the initial treatment group and 85·6% in the second treatment group (P = 0·27). The frequencies of new fractures occurring within 12 months after surgery were 20·9% and 20·6%, respectively.

Within the second treatment group, the VAS improvement rates were 76·7% in the adjacent and 88·2% in the non-adjacent vertebral fracture groups (P = 0·83). However, the frequencies of subsequent new fractures after the second treatment were 31·6% and 5·9%, respectively, being significantly higher in the adjacent vertebral fracture group (P < 0·05).

Conclusions: Additional vertebroplasty for new fractures exerts analgesic effects similar to those of the initial procedure. However, we must note that the second treatment for new adjacent vertebral fractures frequently causes more subsequent new fractures in comparison with non-adjacent fractures.     

Efficacy and safety of vertebral stenting for painful vertebral compression fractures in patients with metastatic disease

Abstract

Background and Purpose:

Painful vertebral compression fractures in cancer patients reduce quality of life and may limit survival. We assessed pain relief, vertebral height restoration, and kyphosis correction following vertebral augmentation using a novel expandable titanium stent implant in cancer patients with painful vertebral compression fractures.

Materials and Methods:

Patients >18 years of age with metastatic disease who presented symptomatic compression fractures of vertebral bodies T5–L5, with or without a history of osteoporosis, were included in the study. Back pain at presentation, immediately after vertebral stenting, and at 1-, 3-, 6-, and 12-month follow-up was estimated using the visual analog scale (VAS). Vertebral height and local kyphotic angle (alpha angle) were measured on lateral standing X-ray before and 1–3 months after stenting.

Results:

Forty-one cancer patients with painful vertebral compression fractures underwent vertebral stenting procedures at 55 levels. There was no perioperative mortality and no significant complication. Median preoperative VAS was 8·0 (range 8–10), falling to 2·0 immediately postop (range 1–6, P = 0·000) and 0 at all subsequent follow-up (P ≤ 0·012). Mean preoperative vertical height loss was 25·8% (range 0–84·0%) versus a postoperative mean of 18·0% (range 0–66·0%, P = 0·000). Median pre- and postoperative kyphotic angle improved from 8·3° (range 0·2°–54·0°) to 7·1° (range 0·2°–25·0°, P = 0·000). Wilcoxon signed rank test or student's t-test was used for comparisons.

Conclusions:

Vertebral augmentation using a novel vertebral stenting system provided immediate and enduring pain relief and improved vertebral height loss and kyphotic angle.     

Percutaneous vertebroplasty compared with conservative treatment in patients with chronic painful osteoporotic spinal fractures

The efficacy of percutaneous vertebroplasty (PVP) for patients with chronic painful osteoporotic compression fractures remains unknown. The purpose of this study was to compare the efficacy of PVP and conservative treatment (CT) for pain relief and functional outcome in patients with chronic compression fractures and persistent pain. Ninety-six patients with chronic compression fractures confirmed by MRI and persistent severe pain for 3 months or longer were prospectively randomly assigned to undergo PVP (n = 46, Group A) or CT (n = 50, Group B). The primary outcome was pain relief and functional outcome at 1 week, 1 month, 3 months, 6 months and 1 year. A total of 89 patients (46 in Group A and 43 in Group B) completed the 1 year follow-up assessment. Pain relief and functional outcomes were significantly better in Group A than in Group B, as determined by visual analogue scale scores, Oswestry Disability Index scores, and Roland Morris Disability scores at 1 week, 1 month, 3 months, 6 months and 1 year (all p < 0.001). The final clinical follow-up assessment indicated complete pain relief in 39 Group A patients and 15 Group B patients (p < 0.001). PVP for patients with chronic compression fractures and persistent severe pain was associated with better pain relief and improved functional outcomes at 1 year compared to CT.     

Incidence of subsequent vertebral body fractures after vertebroplasty

The causal relationship between vertebroplasty and new-onset vertebral fractures remains unproved. We undertook a systematic review and meta-analysis of randomized controlled trials to assess whether vertebroplasty increases the incidence of new vertebral fractures and adjacent vertebral fractures. A systematic literature search of PubMed, EMBASE and Cochrane Library databases up to April 2013 was conducted. Eligible studies were randomized controlled trials of osteoporotic vertebral fracture patients receiving vertebroplasty. Risk ratios (RR) and 95% confidence intervals (CI) were calculated and heterogeneity was assessed with both the chi-squared test and the I² test. Four studies with a total of 454 patients met the inclusion criteria. All four studies described the incidence of new vertebral fractures and three studies described adjacent vertebral fractures. The pooled results revealed that vertebroplasty was not associated with a significant increase in the incidence of new vertebral fractures (RR 1.12, 95% CI 0.75–1.67; p = 0.59) or adjacent vertebral fractures (RR 2.31, 95% CI 0.36–15.06; p = 0.38). Based on available evidence, it cannot be concluded that vertebroplasty can significantly increase the postoperative rate of new vertebral fractures and adjacent vertebral fractures. However, due to some limitations, the results of this meta-analysis should be cautiously accepted, but further studies are needed.     

Osteoporotic burst fracture with spinal canal compromise treated with percutaneous vertebroplasty

Objective

There has been minimal literature reporting on results of osteoporotic burst fracture with spinal canal compromise treated with percutaneous vertebroplasty. Vertebroplasty for treatment of osteoporotic burst fracture is controversial. We want to clarify whether the osteoporotic burst fracture with spinal canal compromise is a contraindication to percutaneous vertebroplasty. To compare the clinical and radiological results between osteoporotic burst and compression fractures treated with percutaneous vertebroplasty.

Patients and methods

From 2005 through 2006, 23 osteoporotic burst fracture patients with asymptomatic spinal canal compromise and 41 osteoporotic compression fracture patients underwent percutaneous vertebroplasty. Pre- and post-operative pain scores, functional and radiographic results and complications were analyzed.

Results

The average canal compromise in study group was 15% (5–49%). The mean post-operative Oswestry Disability Index (ODI), Visual Analogue Score (VAS), kyphotic angle, vertebral body height measurement from the anterior, central and posterior part of the body are all significantly improved in both the study and control groups when compared to pre-operative data. However, there was no significant difference between study and control groups in pre- and post-operative ODI, VAS, kyphotic angle and improvement of body height. There were no significant differences (P = 0.3797) in cement leakage rate between burst and compression groups (47.8% vs 36.6%). All the leakages were minor and without neurological deficit. The percentage of adjacent fractures in both groups also had no significant differences (39.1% in burst and 41.5% in compression group).

Conclusions

Osteoporotic burst fracture with asymptomatic spinal canal compromise is not a contraindication for percutaneous vertebroplasty. This procedure is suitable for both osteoporotic burst and compression fracture with careful surgical technique.     

Combined open decompressive laminectomy and vertebroplasty for treatment of thoracolumbar fractures retrospective review of 41 cases

Background

Vertebral compression fractures are common, and can occur concomitantly in patients with symptomatic degenerative stenosis. Less commonly, complicated vertebral body fractures may involve retropulsion of bone into the spinal canal, resulting in stenosis with myelopathy and/or radiculopathy. Decompression of the neural elements can lead to destabilization and progressive kyphotic deformity. Laminectomy combined with open vertebroplasty provides a way to decompress the neural elements and stabilize the anterior columns in patients who cannot tolerate extended surgical time or complications associated with instrumentation and fusion. The authors describe the combination of decompressive laminectomy and open transpedicular vertebroplasty as a means to decompress neural elements and simultaneously stabilize the anterior vertebral column.

Methods

Forty-one patients with a total of 51 thoracolumbar fractures were included in this retrospective case review. A decompressive laminectomy was performed first, followed by vertebroplasty using an open transpedicular approach. For subjective assessment of outcome, the patients were assessed using the Oswestry Low Back Disability Questionnaire and additional questions pertaining to the patient's condition.

Results

Out of 51 fractures, there were 15 burst fractures and 36 compression fractures. Fracture levels ranged from T12 to S1. The average follow-up period was 27 months (range, 0.5–60 months). The mean post-operative Oswestry score was 16 (range, 0–39), and all patients except for one were subjectively pleased with the results of the procedure and said they would recommend it to others. All patients were able to return to all routine activities of daily living.

Conclusions

The authors’ cases indicate combining open decompressive laminectomies with vertebroplasty can be an effective treatment for patients with complicated thoracic and lumbar fractures without involving bone fusion or spinal instrumentation and with good long-term outcomes.     

Kyphoplasty for the treatment of malignant vertebral compression fractures caused by metastases

Despite the literature supporting the efficacy of kyphoplasty for treatment of osteoporotic vertebral compression fractures in multiple myeloma, few reports exist documenting its use in the treatment of malignant vertebral compression fractures (MVCF) caused by metastases. Accordingly, we sought to evaluate the feasibility, efficacy and safety of kyphoplasty in the treatment of MVCF without epidural involvement. We performed a retrospective review of clinical outcome data for 48 patients with multiple spinal metastases treated with kyphoplasty. Outcome data (vertebral body height variation, degree of kyphosis, visual analog scale score for pain, Oswestry Disability Index score, the Short Form-36 [SF-36] questionnaire score for function) were collected preoperatively, postoperatively, and at 1 month, 6 months, 1 year, and 2 years after treatment. Significant improvements in all of the outcome measures were observed postoperatively and throughout the duration of follow-up. The mean anterior vertebral body height variation improved from 52.7 ± 16.8% preoperatively to 85.3% ± 13.2% postoperatively (p < 0.001). Kyphotic angle improved from 16.4° ± 4.7° preoperatively to 8.4° ± 2.5° postoperatively (p < 0.001). The mean visual analog scale score decreased significantly from presurgery to postsurgery (7.4 ± 2.1 to 3.8 ± 1.6; p < 0.001), as did the Oswestry Disability Index score (71.5 ± 16.7 to 32.4 ± 9.6; p < 0.001). The SF-36 scores for bodily pain, physical function, vitality, and social functioning all also showed significant improvement (p < 0.05). Kyphoplasty is an effective, minimally invasive procedure for the stabilization of pathological vertebral fractures caused by metastatic disease, even in levels with vertebral wall deficiency, leading to a statistically significant reduction in pain, improvement in function and prevention of further kyphotic deformity of the spine.     

经皮椎体成形术治疗椎体恶性肿瘤(附23例报告)

目的探讨经皮椎体成形术治疗椎体恶性肿瘤引起的剧烈疼痛的有效性。方法椎体恶性肿瘤患者共23例,肺癌椎体转移11例,乳腺癌椎体转移5例,骨髓瘤2例,原发性淋巴瘤2例,膀胱癌椎体转移1例,不明来源的恶性椎体肿瘤2例。诊断根据平片、CT、MR和ECT。入院时所有患者均有背部疼痛症状,6点疼痛评分为4.18±0.51分,运动能力评分4.83±0.39分。采用椎弓根入路,以配套活检针抽取组织学标本,配置1.3~1.8g/ml的骨水泥,将骨水泥缓慢注射到椎体中,使骨水泥在椎体病灶内分布、铸形。结果23例33节椎体成形术都获得成功,每节椎体注射骨水泥0.5~7ml。术后2d评估疗效9例患者术后疼痛完全缓解,10例明显缓解,2例中度改善,2例改善不明显。平均疼痛评分降为0.81±0.67,平均运动功能评分1.72±0.41。配对t检验术前、术后比较,有统计学意义(P<0.01)。结论采用经皮椎体成形术治疗椎体恶性肿瘤是一种创伤小、安全、有效的治疗手段,可以明显提高晚期恶性椎体肿瘤患者的生存质量。