计算机导航辅助人工全膝关节置换与常规手术的早期疗效比较

目的对比分析计算机导航辅助人工全膝关节置换与常规手术的早期疗效。方法应用三维骨建模Ceravision系统辅助人工全膝关节(CeraverFrance)置换21例(男5例,女16例),对比术前、术中和术后的相关资料,分析下肢力线重建和韧带平衡的结果;检查术后3个月的膝关节活动度(ROM)与额面松弛度。对照组采用常规手术进行人工全膝关节置换20例。结果Ceravision系统对下肢力线的测量和在膝内、外翻应力下的测量均较X线片更精确。所有患者均获得人工全膝关节胫、股骨假体的满意对位和韧带平衡。术后3个月的关节活动度(ROM)平均屈曲115°;无异常的膝关节松弛度;无髌骨失稳和脱位等并发症。常规手术组的绝大部分也能获得假体的满意对位植入,术后3个月的关节活动度(ROM)平均屈曲109.4°,统计学分析显示两组的ROM比较,差异无统计学意义(P=0.06),额面松弛度比较,差异有统计学意义(P=0.03)。结论应用以三维骨建模为基础的计算机辅助手术系统,优化了人工全膝关节置换,精确地截骨和三维对位,可以更好地反映假体旋转对位情况,获得良好的膝关节屈伸位下关节间隙不衡,保证良好的膝关节韧带张力与平衡稳定,避免髌-股关节并发症,取得比常规手术更合理的额面松弛度,术后的韧带平衡稳定更好,早期疗效满意。     

膝关节外翻畸形的人工全膝关节置换术

目的探讨膝关节外翻畸形患者行人工全膝关节置换术(TKA)的手术方法和临床效果。方法对1996年1月至2004年8月74例87个膝关节外翻畸形TKA手术进行回顾分析。患者男11例,女63例,平均年龄63岁(26~80岁);股胫角(股骨和胫骨解剖轴线的夹角)平均为21·59°(12°~40°);应用后稳定型假体,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解方法。随访检查膝关节活动度、X线外翻角度及KSS评分以评价手术效果。结果术后评价随访时间33·8个月(5个月~9年),根据膝关节活动度数及KSS评分评估关节功能情况。膝关节平均活动度为112·4°(80°~130°),KSS评分平均为81·7分(71~93分),比术前提高了59分;功能评分平均为86·3分,比术前提高了59·8分。所有膝关节在行TKA后外翻畸形基本得到矫正,随访时外翻度数(股胫角)平均为8·7°(0°~11°),较术前有明显改善。随访时1例患者有膝关节轻度不稳症状,1例术前严重髌脱位患者术后髌骨存在半脱位,其余正常。结论对于膝关节外翻畸形患者,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解以及安装后稳定型假体的方法,可取得比较满意的临床效果。     

Reverdin截骨术治疗外翻疗效分析

目的 观察 Reverdin手术治疗外翻的疗效。方法 自 1992年～ 1998年实施 Reverdin手术治疗外翻患者 17例 31足。术前于负重位行 X线检查,测量外翻角平均为 30°,第一跖骨间角平均 10.9°,近端关节固定角平均 19°。按常规治疗外翻的手术方法行趾跖外侧挛缩组织松解,显露跖骨头并切除内侧骨赘;同时按术前 X线片上划出的截骨线,测量楔形基底宽度,对跖骨头楔形内翻进行截骨,充分纠正近端关节固定角。结果 随访 1～ 8年,平均 4年 5个月, 17例 31足,优 10例 19足、良 6例 11足、差 1例 1足,优良率 96.8％。术后无一例出现截骨延迟愈合及跖骨头缺血性坏死。术后负重位 X线片复查示,近端关节固定角平均为 1.95°,平均改善 17°;外翻角平均 14.3°,平均改善 15°;第一跖骨间角平均 5.8°,平均改善 5°。结论 术前测量近端关节固定角是正确选择外翻手术方式的重要依据,可增加手术治疗的成功率,减少术后复发。     

膝内翻全膝关节置换术软组织平衡方法探讨

目的分析骨性关节炎膝内翻角度的组成,探讨全膝关节置换术(totalkneearthroplasty,TKA)中软组织平衡方法。方法分析1999年1月～2003年12月因骨性关节炎行TKA的100例145侧膝内翻患者,其中男18例25个膝关节,女82例120个膝关节。平均年龄62.4岁(45～80岁)。膝关节HSS(hospitalofspecialsurgery)评分38.0±3.2分。根据下肢力线情况准确截骨,恢复膝关节静态骨性对线,然后根据内翻角度组成情况决定软组织松解部位及范围。软组织松解分3步进行,即截骨前暴露时松解、截骨时松解和截骨后安装假体前彻底松解。松解要点包括:韧带及关节囊松解、骨赘清除及髌骨外侧支持带松解。结果术前膝内翻总角度为9.2±3.1°,软组织失衡性内翻占53.2%,胫骨结构性内翻占46.8%,二者差异无统计学意义(P>0.05)。胫骨结构性内翻中胫骨骨性内翻占22.8%,胫骨平台关节面磨损及破坏占24.0%。术后结果表明,平均胫骨平台截骨角度为4.3°,占膝内翻矫正度数的27.9%;软组织平衡术矫正的度数为10.7°,占膝内翻矫正度数的72.1%。术后HSS评分为87.0±4.5分,与术前比较差异有统计学意义(P<0.05)。结论骨性关节炎膝内翻角度由两方面组成:即胫骨结构性内翻和膝关节侧副韧带及软组织失衡导致的内翻。其中后者占膝内翻角度的主要部分,通过松解内侧软组织进行矫正,松解的关键部位为内侧侧副韧带胫骨侧止点及后关节囊。松解时应循序渐进,随时测试,且勿松解过度。     

圆顶形截骨矫治肘内翻畸形

目的评价圆顶形截骨法矫正肘内翻畸形的效果.方法于鹰嘴窝上弧线近侧作圆顶式截骨,旋转纠正肘内翻畸形后交叉克氏针固定,4周去除石膏及克氏针,开始肘关节伸屈及旋转功能锻炼.结果术后随访平均15个月,所有截骨均骨性愈合,肘关节伸屈及旋转活动达术前水平,术前携带角-17°～-35°(平均-27.6°),术后8～15°(平均11.8°),随访未发现矫正角度的丢失,术后肱骨外髁突出畸形显著改善.结论圆顶式截骨术是一种理想的肘内翻畸形矫正方法.     

股骨远端内翻截骨加交锁髓内钉固定治疗膝外翻畸形

目的　探讨股骨远端内翻截骨加交锁髓内钉固定 ,治疗伴有膝外翻畸形的膝关节骨性关节炎的疗效。方法　 1996年 5月～ 2 0 0 0年 8月 ,采用股骨远端内翻截骨加交锁髓内钉固定治疗 16例 (16膝 )伴膝外翻畸形的膝关节骨性关节炎 ,病程 1～ 2 1年 ,平均 5 .2年。按 Ahlback分类 度 10例 , 度 6例。股骨髁上截骨 11例 ,股骨干远端截骨 5例。术前、术后 8周和 2年均行患肢全长 X线片检查 ,以测量股胫角、胫骨角、股骨角及胫股关节面切线夹角及胫股外侧间距大小。按膝关节功能评定标准 ,评定术后膝关节功能恢复情况。　结果　 16例术后获随访 2 5～ 4 6个月 ,平均 31个月。术后 2年随访骨愈合满意 ,1例延迟愈合 ,为股骨干远端截骨患者。皮肤感染 1例。膝关节功能自 5 0 .4± 15 .9分增至 78.5± 12 .9分 ,胫股关节面切线夹角自 5 .6± 2 .9°减少至 1.6± 3.4°,胫股外侧关节间距自 2 .1± 1.8mm增至 4 .7±1.7m m。　结论　股骨远端内翻截骨加交锁髓内钉内固定 ,可作为治疗伴有膝外翻畸形的膝关节骨性关节炎的有效方法之一。     

膝关节内翻屈曲畸形全膝关节置换的软组织平衡

目的探索对膝关节内翻屈曲畸形患者施行的全膝关节置换（total knee arthroplasty,TKA）软组织平衡技术。方法2001年1月～2005年12月,对实施的86例104膝骨性关节炎（osteoarthritis,OA）行TKA的膝内翻屈曲畸形患者进行回顾性研究,对术中的软组织平衡问题进行讨论。其中男19例23膝,女67例81膝;年龄57岁～78岁,平均66岁。行单侧TKA术68例,双侧18例。均为初次行TKA的OA患者。术前内翻角为6～34°,平均12.3°;其中软组织性内翻占总内翻角的56.7%,骨性内翻占43.3%。术前膝关节屈曲挛缩畸形10°以下21膝,10～19°45膝,20～29°22膝,30°以上16膝,平均18.9°。结果患者术前膝关节平均屈曲挛缩18.9°,术中除4例残留5°屈曲挛缩外,其余患者术中膝关节均能达到完全伸直。术后随访6～72个月,平均37个月,6例残留5～10°屈曲挛缩,余膝关节可达到完全伸直。术前内翻角6～34°,平均12.3°;术后测量股胫角170.3～175.6°,平均174.7°,其中2例残留内翻角〉3°。术中、术后发生并发症6例,其中内侧副韧带股骨起点损伤2例;髌骨弹响2例;脑栓塞及腔隙性脑梗塞各1例,经内科治疗后未遗留神经症状。均无皮肤坏死、切口感染及深部感染发生。结论软组织平衡是矫正膝关节内翻屈曲挛缩畸形的主要手段,良好合理的软组织平衡可使高度畸形的膝关节在TKA术后获得明显的功能恢复和畸形矫正。     

胫骨高位外翻截骨并截骨远端前置内移术后胫骨内旋

目的观察胫骨高位外翻截骨并截骨远端前置内移术后的胫骨扭转角和足前进角的变化,探讨胫骨内旋对膝关节生物力学的影响及临床意义。方法膝内翻骨性关节炎并髌股关节炎患者24例(30膝)行胫骨高位外翻截骨并截骨远端前置内移术,男5例7膝,女19例23膝;年龄49～55岁,平均53岁。分别于术前和术后6个月～2年以足印迹法测量患侧足前进角,同时于术前和术后行CT扫描,测量患侧胫骨扭转角。采用t检验对术前、术后两组数据进行统计学分析。结果测量数据显示术前患侧足前进角为8.95°±2.99°,术后6个月时为-2.23°±4.11°;术前胫骨扭转角为33.77°±8.12°,术后为21.27°±8.48°。统计学分析显示足前进角和胫骨扭转角手术前、后差异有统计学意义(P<0.05)。术后胫骨扭转角比术前减小12.50°±2.60°,术后足前进角比术前减小11.08°±2.59°,两者比较差异无统计学意义(P>0.05)。结论胫骨高位外翻截骨并截骨远端前置内移术使胫骨内旋和足前进角减小,影响手术的效果及骨性关节炎病情的进展。     

国人胫骨平台内翻角的测量及其临床意义

[目的]目前人工膝关节置换术(TotalKneeArthroplasty,TKA)中,冠状面上胫骨侧都采用垂直截骨,为了代偿由此所致的胫骨侧非对称截骨,需将股骨假体适度外旋位放置,以后髁轴为参照,其外旋角度等于胫骨平台内翻角。临床术中作者发现参照国外3.00°的标准进行手术时常常出现股骨假体外旋不足所致的一系列并发症,考虑到人种间的区别可能导致的细致解剖上的差异,因而设计了该课题,通过对正常国人X线片的测量,得出其胫骨平台内翻角的数值,为人工膝关节置换术时国人股骨假体的外旋放置角度提供参照。[方法]200例青年健康志愿者摄双侧小腿全长正位片,用AutoCAD软件分别测量小腿机械轴垂直线与胫骨平台面切线(PT角)及双侧股骨髁远端切线的夹角(FT角)。[结果]正常国人的平均PT角为4.06°,FT角为5.00°,均明显大于国外的的参考值。[结论]国人TKA手术以股骨后髁轴为参照时,后髁的外旋截骨角度应>3.00°放置,以5.00°为宜,以获得满意的股骨假体的外旋放置。     

人工全膝关节表面置换术治疗重症膝关节病

目的　探讨人工全膝表面置换术 (TKA)治疗重症膝关节病的疗效。方法　采用TKA共治疗 21例 24膝,其中晚期骨性关节炎 15例 17膝,类风湿关节炎 4例 5膝,全膝关节结核 2例 2膝。按TKA原则施术,重建膝关节负重力线,截骨达到伸屈间隙相等,维护软组织平衡,保持髌骨中置位,获取膝关节充分活动度。结果　平均随访 2 5年,膝关节平均活动度由术前的 58°(30°~100°)改善到 96°(60°~120°),疼痛、跛行明显改善,无感染。结论　对疼痛、畸形、明显影响功能、年龄在 60岁以上的重症膝关节病患者选择TKA治疗,疗效满意。     

Accuracy of Image-Free Computer Navigated Total Knee Arthroplasty Is Not Compromised in Severely Deformed Varus Knees

In severe varus knee deformity, image-free computer navigated total knee arthroplasty (TKA) may result in a malaligned knee. The aim of this study was to compare the results of 17 severe varus knees (≥ 20°) and 81 varus knees (< 20°) that underwent image-free computer navigated TKA and analyze postoperative malalignment. Computer navigated TKA was performed according to standard protocol, and component angles and mechanical axes were evaluated postoperatively with weight bearing full-length standing radiographs. All severe varus knees were corrected to within 3° of neutral lower limb alignment despite having a mean preoperative varus deformities of 22.4°. Neutral alignment was obtained in 88.9% of the varus group (mean preoperative varus deformity of 11.7°), without significant difference between the two groups. No significant difference was found in either the femoral or tibial component angles, or in the frequency of complications. Severity of varus deformity did not affect the accuracy of image-free computer navigated TKA.     

三维骨建模系统在人工全膝关节置换时旋转对位的作用

目的 为了进行人工全膝关节置换时假体旋转对位的量化研究,探讨三维骨建模的计算机辅助手术系统对量化操作的精确性和有效性. 方法 2002年11月 - 2003年6月,采用三维骨建模 Ceravision 系统对 21 例 21 膝保守治疗无效的三间隔骨性关节炎患者行人工全膝关节置换术.男5例5膝,女16例16膝;年龄64～79岁,平均 72.4 岁.左膝10例,右膝11例.主要临床表现为膝关节疼痛和活动受限.病程2～10年.14例膝内翻,7例膝外翻.根据相关的临床体检、影像学和导航系统资料,对术中假体旋转对位量值,并对术后3个月膝关节活动度、膝关节松弛度和髌骨稳定性进行分析. 结果 全部患者术后切口均Ⅰ期愈合.21 例患者均获随访12～16个月,平均13.3个月.术中股骨假体旋转对位内旋 1°～外旋 5°,胫骨假体旋转对位内旋 0°～外旋5°.其中膝内翻患者,股骨假体旋转对位外旋 1°～外旋5°,胫骨假体旋转对位外旋2°～外旋5°膝外翻患者,股骨假体旋转对位内旋1°～外旋4°,胫骨假体旋转对位内旋0°～外旋 4°.术后3个月膝关节活动度,最大屈膝度为 105～130°,平均 115°;膝关节额面松弛度,内侧 0.2～0.5 cm,平均 0.27 cm,外侧 1.0～2.5 cm,平均 1.7 cm.无膝痛、髌骨失稳和脱位等并发症发生. 结论 应用三维骨建模的计算机辅助手术系统,可针对患者个体精确地进行假体旋转对位.     

Varus Gonarthrosis Predisposes to Varus Malalignment in TKA

Postoperative alignment is a predictor for long-term survival of total knee arthroplasty (TKA). The purpose of this study was to evaluate whether or not preoperative deformities predispose to intraoperative malposition of TKA components. A retrospective radiographic analysis of 53 primary TKA cases was performed. Preoperative AP hip to ankle and lateral knee radiographs were compared with postoperative views to evaluate component positioning. The following angles were measured: the hip–knee–ankle (HKA) angle expressing the mechanical axis of the leg, the mechanical lateral distal femur angle (mLDFA), the medial proximal tibia angle (MPTA), the posterior distal femur angle (PDFA), and the posterior proximal tibia angle (PPTA). Postoperative measurement of the HKA revealed 34.0% of the cases had a deviation of >±3° from neutral alignment. Sixteen knees (30.2%) were in varus and, with one exception, all presented with severe varus gonarthrosis prior to surgery with a mean tibiofemoral angle of 12.4° compared with 1.0° of valgus in the optimally aligned group. Patients (93.3%) with preoperative valgus malalignment showed optimal postoperative HKA. Odds ratios for malalignment of TKA for varus knees in comparison with valgus knees were 7.1 for HKA, 2.4 for MPTA, 4.9 for PDFA, and 1.7 for PPTA. The overall number of outliers in the presented data corresponds well with reports from other authors using different implants and guide systems. The presented data indicate that patients with preoperative varus alignment have a higher risk of postoperative implant malposition than patients with valgus alignment. The data supports that preoperative varus deformity predisposes to varus malposition of TKA. The risk for intraoperative malposition is significantly lower in valgus knees.     

Custom-fit total knee arthroplasty (OtisKnee) results in malalignment

We report on 4 patients who underwent total knee arthroplasty with OtisKnee system (OtisMed, Hayward, Calif). An image-free computer navigation system was used to evaluate the deformities and the recommended cuts. The recommended custom cuts were as follows: valgus/varus cuts on the femur (5.5 degrees valgus to 0.5 degrees varus) in reference to the mechanical axis, flexion cuts on the femur (4 degrees -9 degrees of flexion); femoral rotation was within 1 degrees of the epicondylar axis; valgus/varus cut on the tibia (3 degrees of valgus to 7.5 degrees of varus); tibial slope (5.5 degrees of anterior slope to 0.5 degrees of posterior slope). The custom OtisKnee system guides recommended alignment of the components that was more than 3 degrees off of mechanical axis. The potential for malalignment with this system places implants at high risk of early failure.     

Evaluation of knee and hindfoot alignment before and after total knee arthroplasty: a prospective analysis

A prospective study on 100 cases was performed to evaluate the effect of total knee arthroplasty (TKA) on hindfoot alignment, and to compare knee alignment and hindfoot alignment preoperatively and postoperatively. Preoperative knee alignment ranged from 30 degrees of valgus to 13 degrees of varus. Postoperative knee alignment ranged from 14 degrees of valgus to 0 degrees. Preoperative foot alignment ranged from 22 degrees of valgus to 13 degrees of varus. Postoperative foot alignment ranged from 22 degrees of valgus to 11 degrees of varus. Preoperative knee alignment did not correlate with foot alignment (P =.182). Postoperative knee alignment and foot alignment also showed no correlation (P =.222). Preoperative and postoperative knee alignment were correlated, as expected (P =.000). Notably, hindfoot alignment was changed by knee arthroplasty, and changed in a predictable fashion (P=.000). The alignment of the foot before knee arthroplasty was the largest contributing factor to the hindfoot alignment after arthroplasty of the knee. Hindfoot alignment was changed by TKA, and changed in a predictable fashion.     

Influence of limb alignment and prosthetic orientation on patient-reported clinical outcomes in total knee arthroplasty

BackgroundThe relationship between postoperative limb alignment and clinical outcomes in primary total knee arthroplasty (TKA) is well reported, but the instruments used to evaluate clinical outcomes of TKA are mainly scoring systems from the physician's viewpoint, not patient-reported outcomes. The purpose of this study was to investigate retrospectively the relationship between postoperative limb alignment and patient-reported clinical outcomes using the 2011 Knee Society Knee Scoring System (2011 KSS).MethodsThe present study included 155 knees of patients (median age, 74 years) who underwent primary TKA for varus osteoarthritis, with a mean follow-up period of 46 months. The subjects were divided into three groups based on postoperative limb alignment and femoral and tibial component positioning angle (varus, neutral, and valgus). The 2011 KSS scores were compared among the groups.ResultsFor limb alignment, the postoperative objective knee indicator score was significantly lower in the valgus group than in the varus and neutral groups, whereas no significant differences were observed in any subjective categories of the 2011 KSS. However, for the femoral component angle, functional activity scores were significantly lower in the valgus group than in the varus and neutral groups.ConclusionsThe subjective patient-reported score was not affected by the postoperative limb alignment. However, the valgus femoral component angle resulted in lower subjective functional scores. For clinical relevance, postoperative valgus positioning of femoral component should be avoided from patient-reported functional aspects during TKA.     

Total knee arthroplasty after varus osteotomy of the distal part of the femur

BACKGROUND: There is little information in the literature regarding the outcome of total knee arthroplasty following distal femoral varus osteotomy. The purpose of the present study was to evaluate the intermediate-term results of total knee arthroplasty following distal femoral varus osteotomy. METHODS: The study group consisted of nine consecutive patients (eleven knees) who had had a total knee arthroplasty following varus osteotomy of the distal part of the femur. The average age of the patients was forty-four years (range, fifteen to seventy years) at the time of the arthroplasty. The results were evaluated with use of the Knee Society score preoperatively and after a mean duration of follow-up of 5.1 years. Radiographs made preoperatively and at the time of follow-up were evaluated for alignment in the coronal plane. RESULTS: The mean Knee Society knee score was 35 points before the arthroplasty and 84 points after the arthroplasty. The mean Knee Society function score was 49 points before the arthroplasty and 68 points after the arthroplasty. The mean interval between the femoral osteotomy and the total knee replacement was fourteen years (range, two to thirty-two years). A constrained prosthesis was required in five of the eleven knees. Two knees had an excellent result, five had a good result, and four had a fair result. The mean arc of motion improved from 81.8 degrees to 105.9 degrees. The mean radiographic alignment was 3.6 degrees of valgus (range, 7 degrees of varus to 18 degrees of valgus) before the arthroplasty and 3.3 degrees of valgus (range, 1 degrees of valgus to 6 degrees of valgus) at the time of the latest follow-up. There were no infections or wound complications. CONCLUSION: Total knee arthroplasty following distal femoral varus osteotomy decreases pain and improves knee function, but the procedure is technically demanding and is associated with inferior results when compared with those of primary arthroplasty performed in a patient without a prior femoral osteotomy. In the present series, the use of an intramedullary femoral alignment guide increased the tendency to place the femoral component in relative varus angulation (that is, in <5 degrees of valgus). We recommend checking the alignment of the femoral component with an extramedullary guide in knees that have had a previous distal femoral varus osteotomy.     

Primary total knee arthroplasty in patients with severe varus deformity. A comparative study

Varus deformity is a common finding in candidates for total knee arthroplasty (TKA), but very little has been written concerning the problems encountered in correcting these deformities at the time of arthroplasty. Compared to patients without deformities, this group of patients require more attention to the technical aspects of the arthroplasty, especially bony alignment and ligament balancing. Specific operative techniques used to correct severe varus deformities at primary TKA were evaluated, and the clinical and roentgenographic results were compared with those of a control group of patients without preoperative angular deformity. Operative findings and clinical results in 27 knees (20 patients) with a minimum preoperative varus deformity of 20 degrees (average follow-up period, 58.7 months; range, 24-102 months) were compared with those of 40 knees (31 patients) with a preoperative angulatory deformity of less than 5 degrees varus or valgus (average follow-up period, 50.0 months; range, 24-90 months), in whom a minimally constrained, posterior-cruciate-ligament-sparing prosthesis was implanted. Operative time was an average of 30 minutes longer in the varus deformity group. The average knee evaluation score in the varus group was 89 points, and for the nondeformity group it was 92 points (p less than 0.02). There were no fair or poor results in the varus deformity group; there was one poor result in the nondeformity group. Postoperative knee are of motion was 98 degrees in the varus deformity group and 107 degrees in the nondeformity group. After arthroplasty, the average angle between the mechanical axis of the femur and the tibia was 3 degrees varus in the varus deformity group and 0 degree varus in the nondeformity group (p less than 0.006). Postoperative functional scores of patients in the varus deformity group approached, but were not equal to, the nondeformity group. Greater variability in results and longer operative times were needed in the varus deformity group. Postoperative alignment of the varus deformity group tended to be in residual varus.     

Alignment in total knee arthroplasty. A comparison of computer-assisted surgery with the conventional technique

Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA. In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films. The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within +/- 3 degrees varus/valgus) compared with the conventional group (78%, within +/- 3 degrees varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group. Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.     

Navigation in total-knee arthroplasty: CT-based implantation compared with the conventional technique

Background Exact axial limb alignment in total-knee arthroplasty (TKA) is important for a successful outcome. We evaluated the efficiency of computer-assisted implantation in TKA and compared it with the classical surgeon-controlled technique. Patients and methods We implanted 100 TKA using either the computer-assisted technique (50) or the conventional approach (50). There were no significant differences between the groups regarding the preoperative leg deformity. Accuracy of implantation was determined in postoperative long-leg coronal and lateral radiographs. Results A postoperative leg axis between 3 degrees varus and 3 degrees valgus was achieved in 46 patients in the group with computer-assisted implantation and 36 patients in the control group (p=0.01). A significant difference was also seen for the femoral component alignment in frontal plane. No complications influencing the clinical outcome were observed. Interpretation A CT-based navigation system improves the accuracy of TKA, but higher costs and time-consuming planning will mean that its usage is limited to special cases. Additional tools such as ligament balancing, which are presently only available with the CT-free software module, require to be added to the CT-based system.