固定平台后稳定型假体与旋转高屈曲型假体治疗膝骨性关节炎的早期疗效比较

目的评价人工全膝关节置换(total knee replacement,TKR)中使用固定平台后稳定型假体与旋转高屈曲型假体治疗骨性关节炎的早期临床疗效。方法对我院2007年1月—2009年12月收治的68例骨关节炎患者施行TKR手术,其中应用固定平台后稳定型假体32例38膝,旋转高屈曲型假体36例44膝,通过测量手术前及末次随访时的膝关节活动度和美国特种外科医院膝关节评分(hospital for special knee surgery score,HSS)对两种假体置换方式的临床疗效进行比较。结果 68例患者获随访3～26个月,平均19个月。根据HSS评分标准,末次随访时优47例(69.1%),良17例(25.0%),可4例(5.9%),总优良率94.1%。两组之间术前活动度以及术前、末次随访时HSS的差异无统计学意义(P0.05),而旋转高屈曲型假体组在末次随访活动度方面较固定平台后稳定型假体组为高(P0.05)。结论高屈曲度人工膝关节假体在运动学上有潜在的优势,有助于改善关节功能,减轻接触应力和假体磨损;固定平台后稳定型假体手术方式简单、疗效肯定、术后并发症少,对不需要从事高屈曲活动、经济较为困难以及高龄患者是一种可供选择的假体。     

后稳型旋转平台高屈曲假体与普通假体置换后的膝关节功能比较

目的 探讨后稳型旋转平台高屈曲假体膝关节置换的手术适应证及其在改善膝关节功能方面的优越性.方法 应用前瞻性随机对照研究方法,将2009年2月至2009年4月经门、急诊收治的膝关节骨关节炎患者75例94膝随机分为两组,一组接受后稳型旋转平台普通假体置换(PFC sigma RP假体),另一组接受后稳型旋转平台高屈曲假体置换(PFC sigma RPF假体).两组患者的一般情况及术前特种外科医院(the Hospital for Special Surgery,HSS)膝关节评分和膝关节活动范围差异均无统计学意义.根据患者入院顺序再次随机化,由3名术者抽签决定各自的手术对象.术后1、6、12及18个月复查HSS评分及膝关节活动范围,术后18个月对患者进行满意度问卷调查.所有患者术前、术后第3天、3、6、12和18个月拍摄术侧膝关节正、侧位和双下肢站立位全长X线片.结果 70例87膝完成最终随访,普通组33例46膝,高屈曲组34例41膝.术后18个月普通组HSS膝关节评分(92.4±5.0)分,高屈曲组(94.7±7.0)分,两组差异无统计学意义;普通组膝关节活动范围123.0°±15.3°,高屈曲组131.9°±14°,两组差异有统计学意义,高屈曲组大于普通组,但未达到样本量估计时所设定的20°.术后18个月,两组患者的手术满意率均为100%.结论 高屈曲假体与普通假体置换的近期疗效相似.高屈曲假体未显示出在膝关节屈曲活动范围方面的优势.

Abstract：

Objective To explore the indication and the functional advantages of the high-flexion posterior stabilized (PS) rotating-platform mobile-bearing (RP-MB) total knee system. Methods A prospective randomized, controlled trial was performed. Osteoarthritis was the indicators for total knee arthroplasty.From Feb. 2009 to Apr. 2009, 75 patients (94 knees) were randomly assigned to to receive either a highflexion PS, RP-MB total knee system(PFC sigma RPF) or a standard one (PFC sigma RP). There were no statistical difference in the baselines, the preoperative scores of the Hospital for Special Surgery (HSS) and the knee range of motion (ROM) of both groups. The functional status were assessed with Hospital for Special Surgery and the ROM of the knee at the postoperative 1, 6, 12, 18 months. The satisfaction rates were assessed at the postoperative 18 months. The radiographic measurements were t assessed at the postoperative 3days and 3, 6, 12, 18 months. Results A total of 70 participants (87 knees) completed the 18-month followup. At the time of the final follow-up, the average Hospital for Special Surgery knee score was 92.4±5.0points in the standard group and 94.7±7.0 points in the high-flex ion group. The difference was not statistically significant(P ＞0.05). The average maximal flexion was 131.9±14 degrees in the high-flexion group and 123.0±15.3 degrees in the standard group. There was a statistical difference. But it was not enough to confirm our hypothesis that the difference should be higher than 10 degrees. Moreover, the satisfaction rate were 100% in both groups, and no statistical significant difference was found. Conclusion No significant differences were found between standard and high-flexion posterior-stabilized rotating-platform mobile-bearing total knee prostheses in terms of clinical outcomes or range of motion.     

Range of motion of standard and high-flexion posterior stabilized total knee prostheses. A prospective, randomized study

BACKGROUND: The restoration of posterior femoral translation has been shown to be an important factor in enhancing knee flexion after total knee arthroplasty. The purpose of this study was to compare the ranges of motion associated with standard and high-flexion posterior stabilized total knee prostheses in patients managed with simultaneous bilateral total knee arthroplasty. METHODS: Fifty patients (mean age, sixty-eight years) received a standard fixed-bearing knee prosthesis in one knee and a high-flexion fixed-bearing knee prosthesis in the contralateral knee. Two patients were men, and forty-eight were women. At a mean of 2.1 years postoperatively, the patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and The Hospital for Special Surgery. RESULTS: The mean postoperative Hospital for Special Surgery knee score was 90 points for the knees treated with the standard fixed-bearing prosthesis and 89.4 points for those treated with the high-flexion prosthesis. At the time of the final follow-up, the knees with the standard prosthesis had a mean range of motion of 135.8 degrees (range, 105 degrees to 150 degrees ) and those with a high-flexion prosthesis had a mean range of motion of 138.6 degrees (range, 105 degrees to 150 degrees ) (p = 0.41). No knee had aseptic loosening, revision, or osteolysis. CONCLUSIONS: After a minimum duration of follow-up of two years, we found no significant differences between the groups with regard to range of motion or clinical and radiographic parameters, except for posterior femoral condylar offset.     

Comparison of Posterior Cruciate-Retaining and High-Flexion Cruciate-Retaining Total Knee Arthroplasty Design

BackgroundHigh-flexion prostheses have been developed to achieve deep flexion after total knee arthroplasty. The purpose of this study is to compare standard NexGen (CR, cruciate-retaining) and high-flexion NexGen (CR-flex) total knee prostheses in terms of range of motion, clinical and radiologic outcomes, rates of complications, and survivorship in long-term follow-up.MethodsFrom January 2000 to December 2008, 423 consecutive knees underwent total knee arthroplasty using standard CR or CR-flex prostheses. Fifty-three patients were lost to follow-up or declined to participate and 54 died, leaving 290 knees. The minimum duration of follow-up was 8 years (mean 10.1 years). Physical examination and knee scoring of patients were assessed preoperatively, at 6 months and 1 year after surgery, and annually thereafter. Supine anteroposterior and lateral radiographs and standing anteroposterior hip-to-ankle radiographs were obtained preoperatively and at each follow-up.ResultsMean postoperative range of motions in the standard CR group and the CR-flex group were similar, showing no significant difference between the 2 groups (P = .853). At the time of the final follow-up, mean total Hospital for Special Surgery scores were similar between the 2 groups (P = .118). Mean Knee Society pain (P = .325) and function scores (P = .659) were also comparable between the 2 groups. Western Ontario and McMaster Universities Osteoarthritis Index score showed no intergroup difference either (P = .586). The mean hip-knee-ankle angle at the final follow-up was approximately the same (P = .940). Mean coronal angles of femoral and tibial component at final follow-up were also similar (P = .211 and P = .764, respectively). The prevalence of the radiolucent line was 0.6% in the standard CR group and 0.9% in the CR-flex group. Estimated survival rate according to Kaplan-Meier survival analysis was 97.2% in the standard CR group and 95.6% in the CR-flex group at mean follow-up of 10.1 years.ConclusionThis study suggests that excellent clinical and radiographic outcomes could be achieved with both standard and high-flexion CR total knee designs. High-flexion CR prosthesis did not show any advantages over the standard design.     

TC-Dynamic后稳定型人工全膝关节系统术后近期疗效分析

目的探讨应用TC-Dynamic后稳定型人工全膝关节系统行全膝关节置换术(totalknee arthroplasty,TKA)的近期临床效果,评价其临床应用的可行性、安全性和有效性。方法2003年9月～2004年3月,应用TC-Dynamic人工全膝关节系统行TKA10例12膝(TC-Dynamic组),术前膝关节KSS(kneesocietyscore)评分为16.08±11.58分,功能评分为13.75±19.79分,膝关节活动度(rangeofmotion,ROM)为75.00±26.46°。同期使用Scorpio假体行TKA30例50膝(Scorpio组),术前膝关节KSS评分为19.48±9.67分,功能评分为3.16±19.82分,膝关节ROM为80.80±22.82°。比较两组患者术后疼痛缓解情况、KSS评分和功能评分改善情况,以及膝关节ROM的提高程度。结果所有患者术后获随访40～210d,平均130d。TC-Dynamic组术后KSS评分为88.83±4.04分,较术前改善72.75±14.47分,功能评分为79.17±5.15分,较术前改善65.42±19.47分;ROM为107.92±11.57°,较术前提高32.92±32.22°。Scorpio组术后KSS评分为85.68±7.36分,较术前改善66.20±10.44分,功能评分为71.40±12.70分,较术前改善68.24±25.35分;ROM为109.20±11.13°,较术前提高28.40±26.41°。术后各指标组间比较差异均无统计学意义(P>0.01)。两组患者术后X线片均示下肢力线良好,假体位置满意,无透亮线及任何松动迹象。结论TC-Dynamic后稳定型膝关节假体设计合理,术后近期效果良好;但远期疗效仍需大样本长期随访观察。TKA中正确的下肢力线、合理截骨和软组织平衡及屈曲伸直间隙平衡等,是获得良好临床效果和保证假体长期存活的关键。     

不同程度屈膝挛缩畸形人工全膝关节置换的早期疗效比较

目的探讨不同程度屈膝挛缩畸形行人工全膝关节置换术(totalkneearthroplasty,TKA)后的早期疗效。方法回顾性分析2000年1月～2003年12月行TKA的65例97膝屈膝挛缩畸形患者资料。其中骨关节炎51例74膝,类风湿关节炎14例23膝。单膝置换33例33膝,双膝同时置换32例64膝。按屈膝挛缩畸形程度不同将患者分成A、B两组,A组屈曲挛缩<20°(0～15°)32例49膝,B组屈曲挛缩≥20°(20～60°)33例48膝。A、B两组膝关节术前屈曲挛缩度数、活动度(rangeofmotion,ROM)、KSS(kneesocietyscore)评分及功能评分分别为10.7±8.0°、104.6±20.0°、29.1±18.0、32.6±20.7和28.2±7.8°、60.8±26.6°、12.1±13.2、26.8±18.1,各指标组间比较差异均有统计学意义(P<0.05)。术中均采用Scorpio后稳定型骨水泥固定假体,行初期置换。术后3～4d在同一康复师指导下行CPM及主动功能锻炼。结果患者获随访8个月～3年6个月,平均2年7个月。A、B组术后膝关节屈曲挛缩度数、ROM、KSS评分和功能评分分别为0.4±2.1°、108.6±19.0°、82.1±13.8、72.3±29.1和1.3±3.2°、98.6±16.4°、75.9±8.2、81.4±26.9,组间比较差异均无统计学意义(P>0.05)。术后患者总满意度为94.6%,无深部感染及再翻修者。结论膝关节屈膝挛缩畸形严重与否对TKA的早期疗效无明显影响;TKA后ROM有“趋中”现象;术后早期行膝关节功能锻炼也是获得功能改善的重要环节之一。     

Do High-Flexion Total Knee Designs Increase the Risk of Femoral Component Loosening?

Background

The purpose of our prospective, randomized, long-term investigation is to compare the aseptic loosening rate of the femoral component of the total knee prosthesis and clinical and radiographic results of high-flexion posterior cruciate-substituting knee prosthesis or standard posterior cruciate-substituting knee prosthesis in the same patients.

Hi-flexion and gender-specific designs fail to provide significant increases in range of motion during cruciate-retaining total knee arthroplasty

The effects of different femoral component designs on intraoperative range of motion were examined in 40 female patients during primary cruciate-retaining (CR) total knee arthroplasty. After complete bone resection and soft tissue balancing, standard CR, high-flexion, and gender-specific knee trials were sequentially inserted, and maximal flexion and extension under gravity were measured using a navigation system. Average maximal flexions were 134.3° for standard CR knees, 136.2° for high-flexion knees, and 136.4° for gender-specific knees. No significant intergroup differences in intraoperative maximal flexion and extension were found (P > .05). High-flexion and gender-specific femoral designs were found to show subtle increases in intraoperative range of motion as compared with the standard design but no significant differences.     

高屈曲型与传统假体全膝置换对关节活动度影响的Meta分析

[目的]比较高屈曲型和传统假体进行全膝置换(totalkneearthrophsty,TKA)的术后关节活动度的差异.[方法]检索Medline、Embase、Cochranelibrary、CBM等,收集高屈曲型和传统假体TKA的对照试验,系统评价各研究质量,提取关节活动度的量化结果,采用RevMan5.0.18进行Meta分析.[结果]10个研究纳入Meta分析,共1124膝,其中高屈曲型假体组551膝,传统假体组573膝.统计结果显示:5个随机研究组中两组术后ROM无明显差异(P=0.05);非随机研究组中高屈曲的术后ROM略优于传统假体组(WMD=2.82°,95％CI[0.28,5.36],P＝0.03),但也少于5°,缺乏临床意义,并且该结论可能存在一定的发表性偏倚.[结论]目前的证据未能表明高屈曲型假体较传统假体更具提高术后膝ROM的优势.     

性别特异性与普通型假体行全膝关节置换术对关节屈曲范围影响的分析

目的综合评价性别特异性与普通型膝关节假体行全膝关节置换对术后关节屈曲范围（ROM）的影响。方法通过计算机检索中国生物医学文献数据库（CBM）、EMBASE、Cochrane Library、PubMed等数据库,并结合文献追溯、网上查询的方法。收集所有关于性别特异性膝关节假体与普通型膝关节假体行全膝关节置换术后对膝关节屈曲范围（ROM）影响的病例对照研究。以性别特异性假体组和普通型假体组术后ROM的合并效应量（WMD）为评价指标。应用RevMan 5.0软件对各研究结果进行一致性检验和分析,并进行数据合并,评估发表偏倚的影响。结果共6篇文献纳人Meta分析,累计膝关节904例,其中性别特异组460例,普通型假体组444例。性别特异组的术后ROM与传统假体组无差异（WMD=2.39,95%CI[-1.24,6.03],P〉0.05）。结论性别特异性与普通型膝关节假体行全膝关节置换术对术后ROM没有差异。     

术前活动度对人工全膝关节置换术后功能影响的观察

目的回顾性分析患者手术前的活动度对人工全膝关节置换(TKA)术后功能的影响。方法随访2000年1月—2003年12月在我科行TKA的患者65例(97膝),年龄64．8±9．9岁(35～85岁)。其中骨性关节炎55例(81膝),类风湿关节炎10例(16膝)。单膝置换33例,双膝同时置换32例。所有患者按术前膝关节活动度数(ROM)分成两组,≤90°(5°～90°)49膝,>90°(95°～140°)48膝。对两组患者进行疗效(最大屈膝度、活动度、KSS评分及功能评分)对比。所有患者均采用Scorpio后稳定型骨水泥固定的假体,均为初期置换,全部手术由同一组医师完成。术后3 d在同一康复师指导下行患肢CPM及主动功能锻炼至出院。结果平均随访时间29个月(10～44个月)。所有膝关节的活动度从术前的平均84．2°(5°～140°)提高到术后的平均101．6°(40°～140°) (P=0．000);而最大屈膝度数术前的平均103．5°(25°～140°)与术后的平均101．6°(40°～140°)无显著差异(P=0．439);KSS膝关节评分从术前平均19．5分(-24～62分)提高到术后平均78．8分(50～95分)(P=0．000)。所有患者的总满意度为93．8％(61／65)。两个分组比较,ROM≤90°的膝关节ROM及最大屈膝度术后均较术前有提高,而ROM>90°的膝关节平均最大屈膝度术后反而下降。没有翻修及深部感染。结论(1)在影响TKA术后膝关节功能的多种因素中,手术技术是关键因素。(2)在其他因素相同的情况下,术前膝关节的活动度对TKA术后的功能也有很大的影响,术前活动度大的膝关节比那些术前活动度小的膝关节术后能获得更好的功能。     

全膝关节置换的后稳定型假体和保留后交叉韧带疗效比较

目的比较后交叉韧带保留型假体和后稳定型假体在人工全膝关节置换术后早期的临床疗效。 方法选择自2017年1月至2017年6月在上海长海医院接受人工全膝关节置换术的患者，排除患肢有外伤史和手术史的患者，最终纳入74位患者，其中后交叉韧带保留(CR)组35例，后稳定型假体(PS)组39例。分别记录CR组和PS组患者的手术时间、术后引流量、术后3 d血红蛋白浓度，以及术后2周、1年、3年的膝关节活动度(ROM)、最大屈曲角度、西安大略和麦克马斯特大学(WOMAC)评分和美国特种外科医院(HSS)评分。ROM、最大屈曲、HSS、WOMAC在各时间点的比较采用重复测量的方差分析，两组间比较采用独立样本t检验，计数资料组间比较采用卡方检验。 结果CR组的术后引流量明显小于PS组(t＝-16.68，P<0.001)，且术后3 d血红蛋白浓度也明显高于PS组(t＝6.95，P<0.001)。术后2周、1年和3年的随访数据中，CR组的膝关节ROM和最大屈曲度均显著大于PS组，其中术后3年ROM(F＝10.358, P<0.001)，最大屈曲度(F＝10.358, P<0.001)。 结论CR假体和PS假体都可以显著改善患者的膝关节功能，均可作为初次膝关节置换的假体选择。但是在术后早期，CR假体失血量更少，更利于患者术后早期康复。同时与PS假体相比，CR假体在术后早期可能会拥有更好的膝关节活动度和屈曲度。     

Comparison of range of motion after standard and high-flexion posterior stabilised total knee replacement

The purpose of this study was to compare the range of motion after standard version posterior stabilised TKR and high-flexion version TKR in patients receiving bilateral total knee replacement. Thirty-five patients were recruited. The range of motion of the knees was measured clinically with a goniometer in both the pre-operative period and the most recent follow-up. It was found that the pre-operative range of motion was comparable in the two groups. The average post-operative flexion was 105 degrees +/- 13 degrees in the standard version group and 106 degrees +/- 14 degrees in the high-flexion design group (p = 0.201, paired t-test; beta error = 0.073). A slight loss in flexion was observed in the standard version group (0.5 degrees ) as opposed to a slight gain in the high-flexion design group (2 degrees ). However, this was not statistically significant (p = 0.251, paired t-test; beta error = 0.105).     

Safety and efficacy of a rotating-platform, high-flexion knee design three- to five-year follow-up

Our hypothesis was that a high-flexion rotating-platform posterior stabilized (RP-PS) design could maximize range of motion (ROM) and improve deep-flexion activities. Eighty-seven consecutive patients (109 knees) with high-flexion RP-PS design were prospectively followed up for a minimum of 3 years. Radiographic and clinical outcomes were analyzed using Knee Society Score criteria and Western Ontario and McMaster Universities Osteoarthritis Index. Good to excellent clinical scores were achieved in 96% of the knees. There were no cases of infection, malalignment, loosening, osteolysis, or spinout. The mean preoperative ROM improved from 110.7° to 124° postoperatively. High-flexion activities such as squatting and kneeling were achieved in 62% and 60% of patients, respectively. High-flexion knee implant is safe and improves ROM and deep-flexion activities. Persistent pain is an important cause of dissatisfaction after total knee arthroplasty.     

活动和固定衬垫型假体在全膝关节表面置换术中的早期临床比较研究

目的通过文献回顾以及病例观察比较活动衬垫型假体和固定衬垫型假体在人工膝关节表面置换中的早期应用情况。方法2003年2月至2004年10月共对94例骨关节炎患者行初次全膝关节表面置换术。全部病例选用不保留后交叉韧带骨水泥型假体。A组(固定衬垫型假体)29例患者,30侧关节(20侧选用DePuy假体,10侧选用Centerpulse假体)。B组(活动衬垫型假体)65例患者,68侧关节,全部选用Centerpulse假体。A,B两组术前资料进行HSS评分、年龄、性别等可比性分析。术后6周、3个月、6个月、1年分别随访,进行HSS评分、患者满意度调查等评价。所得数据采用SPSS10.0软件系统进行统计学分析。结果A、B两组术后6周、3个月、6个月、1年所得HSS评分进行阶段统计学分析,所得P值分别为0.414,0.108,0.235,0.452,两组术后HSS评分差异无统计学意义。术后1年,两组膝关节活动度比较A组,平均ROM为108°(95°~118°);B组,平均ROM为107°(90°~120°),两组关节活动度差异无统计学意义(P>0.05)。术后1年,A组患者主诉4侧关节(13.7%)仍有疼痛,B组9侧关节(13.1%)主诉患肢仍有疼痛;A组90%患者对手术效果满意,B组88%患者对手术效果满意。结论本组研究结果尚未证实活动衬垫型假体相对于固定衬垫型假体在早期人工关节表面置换术后的优越性。     

高屈曲假体初次全膝关节置换术早期随访结果的Meta分析

目的 分析有关高屈曲假体与普通假体初次全膝关节置换术后疗效比较的文献,对术后关节活动度(range of motion,ROM)及膝关节功能评分(HSS、KSS、WOMAC)进行Meta分析.方法 检索Medline(1966年1月至2009年10月),Embase(1966年1月至2009年10月),维普资讯(1989年1月至2009年10月)和CNKI(1979年1月至2009年10月)等数据库中关于高屈曲假体与普通假体在初次伞膝关节置换术中应用的疗效比较的前瞻性随机对照研究,纳人符合标准的文献,提取相关数据输入Review Manager 4.2软件进行统计学分析.术后ROM和膝关节功能评分均采取权重均差(weighted mean difference,WMD)进行评价.结果 共6篇文献符合纳入标准,经改良Jadad评分均判定为高质量研究.纳入病例466例,高屈曲假体组和普通假体组术后ROM合并WMD为1.64195%C1(-0.04,3.32),P=0.06],膝关节HSS评分合并WMD为0.34[95%CI(-1.12,1.79),P=0.65],膝关节KSS评分合并WMD为-0.67[95%CI(-2.22,0.89),P=0.40],膝关节WOMAC评分合并WMD为1.66195%C1(-4.03,7.35),P=0.57].高屈曲假体组与普通假体组的ROM、HSS、KSS、WOMAC的差异无统计学意义.结论 初次全膝关节置换术后高屈曲假体组相比普通假体组ROM无明显改善,膝关节功能评分无明显差异.     

Polyethylene wear particles in synovial fluid after total knee arthroplasty

The aims of the current study were to examine polyethylene particles in synovial fluid at an early stage, and to compare a newly introduced medial pivot total knee prosthesis with an established posterior-stabilized total knee prosthesis. Synovial fluid was obtained 1 year after knee arthroplasty from 17 patients with well-functioning prostheses (22 knees, 11 posterior-stabilized prostheses and 11 medial pivot prostheses) under complete sterile conditions. Polyethylene particles were isolated and analyzed by scanning electron microscopy. Particle size (equivalent circle diameter) was 0.78 +/- 0.08 microm (mean +/- standard error) in posterior-stabilized prostheses and 0.67 +/- 0.06 microm in medial pivot prostheses. Particle shape (aspect ratio) was 2.30 +/- 0.22 in posterior-stabilized prostheses and 1.90 +/- 0.16 in medial pivot prostheses. The total numbers of particles were 1.16 +/- 0.57 x 10(8) in posterior-stabilized prostheses and 9.01 +/- 2.95 x 10(6) in medial pivot prostheses. Particles were smaller and rounder in medial pivot prostheses than in posterior-stabilized prostheses, but the differences were not significant. The difference in the common logarithm of particle number was significant. The medial pivot prosthesis generated less wear particles than the posteriorstabilized prosthesis, and these findings may have an impact on the incidence of osteolysis and aseptic loosening.     

Knee kinematics with a high-flexion posterior stabilized total knee prosthesis: an in vitro robotic experimental investigation

BACKGROUND: An analysis of contemporary total knee arthroplasty reveals that, on the average, patients rarely flex the knee beyond 120 degrees. The biomechanical mechanisms that inhibit further flexion after total knee arthroplasty are unknown. The objective of the present study was to investigate the capability of a single design of a fixed-bearing, high-flexion posterior stabilized total knee arthroplasty system (LPS-Flex) to restore the range of flexion to that of the intact knee. METHODS: Thirteen cadaveric human knees were tested, with use of a robotic testing system, before and after total knee arthroplasty with the LPS-Flex prosthesis. The passive path and the kinematics under an isolated quadriceps force of 400 N, under an isolated hamstring force of 200 N, and with these forces combined were determined. Posterior femoral translation of the lateral and medial femoral condyles and tibial rotation were recorded from 0 degrees to 150 degrees of flexion. RESULTS: The medial and lateral condyles of the intact knee translated posteriorly from full extension to 150 degrees, reaching a mean peak (and standard deviation) of 22.9 +/- 11.3 mm and 31.9 +/- 12.5 mm, respectively, under the combined muscle forces. Following total knee arthroplasty, the amount of posterior femoral translation was lower than that observed in the intact knee. At 150 degrees, approximately 90% of the intact posterior femoral translation was recovered by the total knee replacement. Internal tibial rotation was observed for all knees throughout the range of motion. The cam-spine mechanism engaged at approximately 80 degrees and disengaged at 135 degrees. Despite the absence of cam-spine engagement, further posterior femoral translation occurred from 135 degrees to 150 degrees. CONCLUSIONS: The tibiofemoral articular geometry of the intact knee and the knee after total knee arthroplasty with use of the LPS-Flex design demonstrated similar kinematics at high flexion angles. The cam-spine mechanism enhanced posterior femoral translation only at the mid-range of flexion. The femoral component geometry of the LPS-Flex total knee prosthesis may improve posterior tibiofemoral articulation contact in high flexion angles.     

High-Flexion Total Knee Replacement: Functional Outcome at One Year

Implants designed for enhanced flexion offer the prospect of improved function after total knee replacement (TKR). Whereas most studies evaluating these implants have focused on the range of knee flexion achieved, this study investigated the quality of function in deep knee flexion. The influences of residual pain and maximum flexion angle on function in deep knee flexion were also examined. Eighty-three patients (100 knees) were prospectively followed for 1 year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis. Range of motion was measured and Knee Society scores were calculated. A questionnaire evaluated residual knee pain and function in high-flexion activities. Mean Knee Society score was 95, and mean knee flexion was 125°, yet 20% of patients could neither kneel, nor squat, nor sit on their heels. Fifty-seven percent were able to kneel without significant difficulty; 69% were able to squat without significant difficulty; and 46% were able to sit on their heels without significant difficulty. Function in deep flexion correlated with pain scores but did not correlate with knee flexion angles or Knee Society scores. Results 1 year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis are encouraging, but one in five patients remain significantly limited in high-flexion activities.