术中应用不同假体对全膝关节置换术后引流的影响

目的 探讨术中使用后方稳定型（posterior cruciate stabilization, PS）与后交叉韧带保留型（posterior cruciate retention, CR）假体对全膝关节置换术（total knee arthroplasty, TKA）术后引流的影响。方法 回顾性分析2018年6月至2018年10月终末期骨性关节炎行全膝关节置换的患者102例，其中62例采用后交叉韧带保留型（CR）假体（CR组），40例采用后稳定型（PS）假体（PS组）。所有患者术中均使用止血带、关节腔注射氨甲环酸（tranexamic acid, TXA），术后患肢屈曲1 h、引流管夹毕1 h、患肢冰敷24 h。收集术后2、4、24、48 h引流量和引流液中血红蛋白（hemoglobin, HB）含量，以及术后2、24、48 h静脉血中的血红蛋白（HB）含量。统计术后输血情况、早期感染并发症例数。结果 102例患者随访3个月，术后总引流量CR组（292.9±128.3）mL比PS组引流量为（355.2±136.8）mL少，两组比较差异有统计学意义（P＜0.05）。术后1 d的CR组的引流量比PS组少，两组比较差异有统计学意义（P＜0.05）。术后24 h的CR组引流液中血红蛋白含量比PS组明显下降，两组比较差异有统计学意义（P＜0.05）。术后24、48 h的PS组静脉血中血红蛋白含量比CR组明显下降，两组比较差异有统计学意义（P＜0.05）。CR组2例输了2 U红细胞，PS组2例输了1 U红细胞、9例输了2 U红细胞。102例患者术后早期均未出现感染并发症。结论 与PS假体相比，采用CR假体可减少患者的失血量、术后引流量少、降低全膝关节置换术后贫血的发生、减少围术期输血率。     

术前膝内外翻畸形程度对全膝关节置换术后疗效的影响研究

目的 探讨术前膝内外翻畸形程度对全膝关节置换术（TKA）后疗效的影响。方法 回顾性分析2016年3月至2020年6月因膝关节骨关节炎于武汉大学人民医院行初次全膝关节置换术的患者174例（178膝）。依据术前患肢髋膝踝角度分为A组（膝内翻≤10°）、B组（10°＜膝内翻≤20°）、C组（膝外翻≤10°）、D组（10°＜膝外翻≤20°）。其中,男27例,女147例;年龄65 ～ 88岁,平均（72.8±6.2）岁。记录术前及术后1周术侧HKA角,术前1周及术后末次随访时的HSS、ROM、AKS评分、VAS评分、AOFAS评分。对以上指标进行组间比较及相关性分析。结果 174例患者均获得随访,随访15 ～ 66个月,平均（42.0±16.0）个月。各组术后1周时HKA角均较术前明显改善（P＜0.05）;末次随访时各组患者的HSS评分、ROM评分、AKS功能和活动评分、AOFAS评分均较术前明显提高（P＜0.05）;VAS评分均较术前明显下降（P＜0.05）。不同程度内/外翻的术前各项指标、术后HKA及优良率、AOFAS评分比较,内/外翻程度越严重,结果越差（P＜0.05）;术后HSS评分、ROM、AKS功能及活动评分、VAS评分比较,差异均无统计学意义（P＞0.05）。膝内翻患者的术前HKA角与术前HSS评分、ROM、AKS活动及功能评分、VAS评分、AOFAS评分、术后AOFAS评分正相关（P＜0.05）,与术后HSS评分、ROM、AKS活动及功能评分、VAS评分无相关（P＞0.05）。膝外翻患者的术前HKA角与术前HSS评分、ROM、AKS活动及功能评分、AOFAS评分、术后AOFAS评分负相关（P＜0.05）,与术后HSS评分、ROM、AKS活动及功能评分、VAS评分、术前VAS评分无相关（P＞0.05）。结论 从中期随访来看,患者术前膝内、外翻畸形的严重程度对术后HKA对线优良率、术后踝关节功能、术前膝关节功能有显著影响,而对术后膝关节功能无显著影响。     

后稳定型与后交叉韧带保留型膝关节假体在人工膝关节置换术后的早期临床疗效比较分析

目的比较后稳定型膝关节假体(Posterior Stabilized Total Knee Prostheses PS)与后交叉韧带保留型膝关节假体(Posterior Cruciate-Retaining Total Knee Prostheses CR)在人工膝关节置换术(Total Knee Arthoplasty TKA)后的临床疗效,并分析两种假体在TKA术后可能存在的相关问题。方法回顾自2010年1月至2012年12月我院收治的晚期骨关节炎、并进行人工全膝关节置换术治疗的66位患者资料,其中PS假体30例,CR假体36例,观察两组患者手术时间、术后引流量,以及术后2周、1年、3年的下肢力线、膝关节活动度(Range Of Motion ROM)、膝关节最大屈曲角度、术后视觉模拟评分法((Visual Analogue Score VAS)、纽约特种外科医院膝关节功能评分(hospital for special surgery knee score HSS)评分、髋膝关节炎评分(The Western Ontario and Mc Master Universities,WOMAC,Osteoarthritis Index)。结果 PS组的术中手术时间、术后引流量明显大于CR组,差异具有统计学意义(P0.05),术后两周PS组膝关节ROM、膝关节最大屈曲角度明显大于CR组,差异具有统计学意义(P0.05),而在术后1年、3年的随访数据中均无明显差异。结论对于无严重畸形的初次膝关节置换,后稳定型膝关节假体与后交叉韧带保留型膝关节假体均具有重要的临床使用价值,可有效改善患者的膝关节功能,降低膝关节疼痛评分等。     

后交叉韧带保留型和后稳定型全膝关节假体治疗晚期膝骨关节炎早期关节遗忘度评价

目的 比较后交叉韧带保留型和后稳定型全膝关节假体治疗晚期膝骨关节炎的早期膝关节功能评分与关节遗忘度评分,评价并分析两类假体在早期关节遗忘度评分方面的差异。方法 采用回顾性队列研究上海中医药大学附属光华医院关节外科2016年10月至2020年10月期间行全膝人工关节置换术患者共172例。按不同假体类型进行分组,其中CR组共84例、PS组共88例,出院后对患者术后1、3、6、12、24个月进行门诊复查,进行关节遗忘评分、膝关节功能HSS评分、目测类比评分与膝关节活动度评价。结果 (1)172例患者均随访24～40个月,平均（32.03±5.01）个月,期间均未出现假体周围感染、松动、脱位及僵硬等并发症;(2)HSS评分：术后2年CR组与PS组HSS评分均明显好于术前,差异具有统计学意义（P<0.001）,两组患者术后2年膝关节HSS评分改善程度差异无统计学意义（P>0.05）。(3)VAS评分：术后2年CR组与PS组VAS评分均明显好于术前,且差异具有统计学意义（P<0.001）,两组患者术后2年VAS评分的改善程度差异无统计学意义（P>0.05）。(4)FJS-1...     

胫骨髁外翻截骨术治疗创伤性膝关节炎的早期临床疗效分析

目的 探讨胫骨髁外翻截骨术（TCVO）治疗陈旧性内侧胫骨平台骨折并发创伤性膝关节炎（TKOA）的早期临床疗效。方法 回顾性分析2016年6月至2021年6月于苏州市立医院关节外科接受TCVO手术治疗陈旧性内侧胫骨平台骨折并发TKOA的18例患者的术前及术后相关临床资料,所有患膝均为陈旧性内侧胫骨平台骨折保守治疗后畸形愈合并发膝内翻TKOA。患者发生胫骨平台骨折至TCVO手术治疗的时间为49 ～ 171个月,平均（111.1±33.8）个月;患膝内翻角度为6.81° ～ 14.49°,平均10.95°±2.62°;关节线会聚角（JLCA）为3.58° ～ 8.12°,平均5.95°±1.42°。所有患者于术前及术后3个月拍摄站立位双下肢全长X线片、膝关节正侧位X线片并测量患膝内翻角度、胫骨近端内侧角（MPTA）、JLCA、胫骨平台后倾角（PTS）,评估术前、术后下肢力线以及膝关节对合状态的变化情况。依据术前及术后3、12个月的患膝关节活动度（ROM）、疼痛视觉模拟评分（VAS）、西安大略与麦克马斯特大学（WOMAC）骨关节炎指数、膝关节损伤与骨关节炎评分（KOOS）评估早期临床疗效。结果 18例患者均获得随访,随访时间为14 ～ 65个月,平均随访（27.4±14.4）个月。术后3个月时,患膝内翻角、JLCA均较术前显著降低,差异均具有统计学意义（P＜0.05）;MPTA与术前相比有显著提升,差异有统计学意义（P＜0.05）;PTS与术前相比差异无统计学意义（P＞0.05）。术后3、12个月时,患膝关节ROM、VAS、WOMAC、KOOS评分均较术前有显著好转,差异均具有统计学意义（P＜0.05）。结论 采用TCVO治疗陈旧性内侧胫骨平台骨折并发TKOA可以取得良好的早期临床疗效,有效矫正膝关节内翻畸形,缓解膝关节疼痛及改善膝关节功能。     

HSS膝关节康复方案对单髁置换术后早期关节功能和步态的影响

目的 研究美国特种外科医院（hospital for special surgery, HSS）膝关节康复方案对膝关节单髁置换术（unicompartmental knee arthroplasty, UKA）术后关节功能及步态的近期影响。方法 回顾性分析2018年1月至2021年6月间在湖北省中医院行UKA术的60例患者。将采用HSS膝关节成形术康复指南进行康复治疗的30例患者作为HSS组;将同期采用常规康复方案的30例患者作为常规组。记录术后1周、3个月、6个月、1年两组患者的膝关节活动范围（range of motion, ROM）、美国特种外科医院膝关节HSS评分、人工关节遗忘指数（forgotten joint index, FJS）。分别于术后6个月、1年时采用GaitWatch三维步态分析及运动训练系统进行步态信息数据的采集,并比较两组间差异。结果 两组均完成术后1年以上随访,膝关节功能比较：术后3个月随访,HSS组膝关节ROM、HSS评分高于常规组,差异有统计学意义（P＜0.05）;术后6个月随访,HSS组患者膝关节ROM、HSS评分高于常规组,FJS评分低于常规组,差异有统计学意义（P＜0.05）;术后1年随访,HSS组的HSS评分高于常规组、FJS评分低于常规组,差异有统计学意义（P＜0.05）。步态参数比较：术后6个月随访,HSS组的步数、步长及单足支撑相较常规组高,差异有统计学意义（P＜0.05）;术后1年随访,HSS组的步数、步频、单足支撑相较常规组高,差异有统计学意义（P＜0.05）。结论 HSS膝关节成形术后康复方案在UKA术后早期可显著改善膝关节功能和步态,有利于UKA术后早期康复。     

国产后稳定型全膝关节置换假体的近期疗效分析

目的观察国产后稳定型全膝关节假体置换的近期疗效。方法回顾2011年3月~2012年3月初次膝关节置换患者36例(36膝)。观察组使用德骼拜尔假体18例(18膝),对照组使用Link假体18例(18膝)。全部患者获术后随访,比较两组患者的手术时间、出血量、假体安放时间、术后膝关节功能HSS评分等情况作统计分析。结果平均随访时间观察组12.17个月,对照组12.43个月。两组患者的手术时间、术中出血量、假体安放时间之间的差异无统计学差异(0.05)。术前、术后HSS评分及WOMAC评分两组间均无统计学差异(0.05)。结论国产后稳定型全膝关节假体置换术后近期疗效满意,其远期疗效有待观察。     

全膝关节表面置换术后切口非感染性渗出的危险因素分析

目的 探讨引起全膝关节表面置换术（TKA）术后切口非感染性渗出的危险因素。方法 回顾性收集2018年1月至2022年4月河南大学第一附属医院骨科一病区因膝关节骨性关节炎行全膝关节表面置换术的210例患者的临床资料。根据术后切口是否发生非感染性渗出分为渗出组（16例）和非渗出组（194例）。将可能引起切口非感染性渗出的因素纳入单因素与多因素分析，找出引起切口非感染性渗出的因素。结果 经单因素分析，BMI、术前白蛋白、手术部位、手术时间、术中出血量、缝合方式、加压包扎时间差异有统计学意义（P＜0.05）。经二元Logistic回归分析，BMI（OR=1.218，P=0.014）、术前白蛋白（OR=0.680，P＜0.001）、缝合方式（OR=7.967，P=0.002）差异有统计学意义。结论 BMI、术前白蛋白水平、缝合方式是影响TKA术后切口非感染性渗出的危险因素。     

Deluxe-ps膝关节假体在一期双膝关节置换过程中的应用

背景：Deluxe-PS型人工膝关节假体是根据中国人膝关节解剖特点尤其是股骨髁的形态特征而设计的,其膝关节假体股骨髁内外侧距(M-L)较进口假体少3.5 mm。 目的：探讨Deluxe-ps膝关节假体行一期双膝关节置换中的近期疗效。 方法：纳入使用Deluxe-ps型膝关节假体行一期双侧膝关节置换的膝关节炎患者15例(30膝)设为实验组,对照组为同期采用P.F.C.Sigma膝关节假体行一期双侧膝关节置换的20例患者(40膝)。采用KSS评分和关节功能HSS评分、膝关节关节活动度评估两组手术前、后膝关节功能,对比两组手术时间、及术中输血量。 结果与结论：两组患者置换后均得到12-24个月随访,平均16个月。置换后患者膝关节疼痛均缓解,关节功能恢复满意。两组膝关节置换后与置换前KSS评分、HSS评分及膝关节关节活动度比较,差异均有显著性意义(P < 0.05)。置换后,两组间KSS评分和HSS评分及膝关节关节活动度,差异均无显著性意义(P > 0.05),两组间置换过程中出血量比较,差异均无显著性意义(P > 0.05),手术时间比较,差异有显著性意义(P < 0.05)。说明采用Deluxe-ps膝关节假体行一期双膝关节置换近期疗效满意。     

单半径假体对全膝关节置换术后伸膝装置功能的影响

目的 探讨单半径全膝关节假体全膝关节置换术(TKA)对患者伸膝装置功能改善的影响以及临床疗效。方法 采用回顾性队列研究方法。纳入同济大学附属东方医院关节外科2012年6月—2015年1月收治的60例中、重膝骨关节炎患者的临床资料,其中女50例、男10例,年龄53～79岁。60例患者均行TKA治疗,其中使用单半径假体(Triathlon假体)30例(30 膝)为观察组,使用多半径假体(Nexgen假体)30例为对照组。通过比较两组患者术前与术后3个月通髁线至髌骨中心距离的增加值,评估伸膝装置功能;在术后6周、3个月、6个月、1年、2年,通过比较两组患者美国膝关节协会评分(AKSS)和膝关节伸直后段(屈曲前段)疼痛发生率,评价手术疗效。结果 两组患者手术均顺利完成;术后随访3~5(4.2 ±1.2)年,均无感染、深静脉血栓、假体松动及假体周围骨折等并发症发生。观察组术后3个月通髁线至髌骨中心距离较术前增加(3.30±4.08)mm、对照组增加(1.58±2.64)mm,术后6周、3个月、6个月、1年、2年各时间点观察组AKSS评分均高于对照组,差异均有统计学意义(P值均＜0.05),膝关节伸直后段(屈曲前段)膝前痛发生率均较对照组有下降趋势,但差异均无统计学意义(P值均＞0.05)。结论 单半径膝关节假体TKA治疗中、重度骨关节炎近期临床疗效可靠,术后伸膝装置功能改善,建议临床推广应用。     

新型国产膝关节假体用于全膝关节置换术的临床研究

目的 通过随机对照临床试验,验证新型国产膝关节假体临床应用的安全性和有效性.方法 本研究采用多中心、随机、单盲、阳性平行对照设计,自2017年3月至2019年3月在全国6家医院共招募72例受试者,试验组和对照组各36例.试验组使用新型国产膝关节假体,对照组使用成熟的膝关节假体.所有受试者在术前和术后3个月、6个月、1年...     

全膝关节置换治疗成人膝外翻畸形：胫股角及膝关节活动度变化

背景：膝外翻畸形施行人工全膝关节置换难度很大,涉及面多,争议亦颇多。 目的：观察全膝关节置换治疗成人膝外翻畸形的手术方法和临床效果。 方法：对12例15膝采用髌骨内侧入路,正确截骨,选择性的软组织松解,恢复膝关节正常的力线和软组织平衡,采用后稳定型假体进行全膝关节置换,获得膝关节的稳定,置换后采取针对性的康复训练,置换前后测量胫股角,并置换后定期随访检查膝关节活动度并进行HSS评分。 结果与结论：所有患者获得随访均>6个月。置换前胫股角平均21.47°降低至置换后的5.47°(P < 0.01),膝关节活动度由置换前的81.33°提高到121.07°(P < 0.01);HSS评分由置换前的25.47分提高到89.87分(P < 0.01)。置换后1例出现关节积液较多,2例出现膝关节内测不稳。无髌骨脱位或半脱位,下肢力线均恢复正常。提示成人膝外翻畸形经全膝关节置换后外翻畸形均得到纠正,功能较前明显改善。     

Rotational kinematics differ between mild and severe valgus knees in total knee arthroplasty

BackgroundThere is no consensus regarding femorotibial rotational kinematics in total knee arthroplasty (TKA) for valgus knee deformity. Additionally, whether the degree of valgus deformity influences intraoperative rotational kinematics and postoperative clinical scores remains unclear. The objectives of this study were to investigate whether the valgus angle is associated with intraoperative rotational kinematics in TKA for valgus knee deformity and to examine the relationship between rotational kinematics and postoperative clinical results.Materials and methodsA total of 24 knees with valgus deformity for TKA were included in this study and were divided into two groups depending on the femorotibial angle (FTA); there were 11 knees in the severe valgus group (FTA < 160°) and 13 knees in the mild valgus group (FTA ≥ 160°). Intraoperative femorotibial rotational kinematics from knee extension to flexion were evaluated using an image-free navigation system and postoperative clinical results (range of motion and subjective outcomes) were evaluated 1 year postoperatively. All parameters were compared between the two groups.ResultMild valgus knee showed tibial internal rotation during knee flexion before implantation, whereas severe valgus knee showed tibial external rotation during knee flexion before implantation. The postoperative flexion angle was positively correlated with the tibial internal rotation angle after implantation in the mild valgus group only.ConclusionIntraoperative rotational kinematics before implantation differed between mild and severe valgus knee deformity in TKA. Intraoperative tibial rotation influenced the postoperative knee flexion angle in mild, but not severe, valgus knee deformity. Ideal postoperative rotational kinematics may be different between the two groups and the difference may be taken into consideration in implant selections and surgical techniques.     

Different targets of mechanical alignment do not improve knee outcomes after TKA

BackgroundAccurate alignment is a basic principle of TKA surgery, but achieving alignment within this target may not translate into superior outcomes after surgery.PurposeTo assess if neutral TKA mechanical alignment was associated with superior knee outcomes and to examine the effect of various aspects of pre-operative and post-operative alignment on knee function.MethodsAnalysis of a database of 444 TKA patients between June 2009 and October 2016. Knee outcomes (WOMAC, AKSS and knee range of motion) were collected before surgery and during follow-up at a minimum of six months.ResultsAnalysis included 444 TKA patients (62% female, mean age 66 years, mean follow-up 23 months). Deformity varied from 21° varus (mean = 7.9, SD = 2.8) to 17° valgus deformity (mean = 7.7, SD = 2.8). Pre-operatively, 101 (23%) knees were in native neutral mechanical alignment, while 278 (63%) were in varus and 65 (15%) were in valgus. Post-operatively, a group of 365 (82%) TKA were found to be in neutral mechanical alignment and a group of 79 (18%) TKA were noted to be ‘Outliers’ (17 [4%] TKA > 3° varus and 62 [14%] TKA > 3° valgus alignment). Restoration of the target of alignment of 0 ± 3° or 0 ± 1°, did not have better functional outcomes scores, range of motion or prosthesis longevity than those in the outlier range.ConclusionNeutral TKA alignment did not appear to be a significant contributing factor to the improvement in knee function in short-medium term follow-up.     

The effectiveness of minimally invasive total knee arthroplasty to preserve quadriceps strength: A randomized controlled trial

We performed a single-center, randomized, double-blind study to compare muscle strength in patients who had undergone primary total knee arthroplasty (TKA), performed using either a minimally invasive or a conventional surgical technique. We evaluated 30 knees in healthy age-matched subjects, 22 knees after conventional TKA (conventional group), and 23 knees after minimally invasive surgery TKA (MIS group). The Hospital for Special Surgery (HSS) score, Oxford knee score (OKS), and isokinetic (60º/s) muscle strength were evaluated the day before surgery and 3, 6, and 12 months after surgery. HSS and OKS improved significantly over time during follow-up (p < 0.001), but there was no significant difference between the groups (p > 0.05). The extensor peak torque (EPT) and flexor peak torque (FPT) improved significantly over time (p < 0.001) and EPT was greater in the MIS group than in the conventional group during the follow-up period (p < 0.05). There was no difference in FPT and the hamstring-to-quadriceps ratio between the groups. Although MIS patients had a significant deficit in extensor strength following TKA, compared with healthy controls, this approach offers a significant improvement in extensor muscle strength over conventional surgery. These results suggest that the MIS approach results in better outcomes with regard to maintaining extensor strength than the conventional surgical approach.     

Comparison of intraoperative soft tissue balance measurement between two tensor systems in total knee arthroplasty

BackgroundDifferences in measurement outcomes using different tensors in total knee arthroplasty (TKA) remain unknown. This study aimed to compare intraoperative soft tissue balance between two measurement systems in TKA.MethodsThis study included 24 cruciate-retaining (CR) and 27 posterior-stabilized (PS) TKAs for varus-type osteoarthritis. All TKAs were performed with the measured resection technique. Intraoperative soft tissue balance was assessed with femoral component placement and patellofemoral joint reduction throughout the range of motion. Measurements were performed using the Offset Repo-Tensor (Zimmer) and Ligament Sensor Tensor (Depuy). Joint component gaps and varus/valgus ligament balance were compared statistically in CR and PS TKAs.ResultsJoint component gaps with the Offset Repo-Tensor were significantly larger at 0°, 10°, 30°, and 60° of knee flexion in CR TKA and at all knee flexion angles, except 0° and 135°, in PS TKA than those with the Ligament Sensor Tensor (P < .05). Varus balance with the Offset Repo-Tensor was significantly larger at 0°, 10°, and 30° of knee flexion in CR TKA and at 10°, 30°, 60°, 90°, and 120° of knee flexion in PS TKA than that with the Ligament Sensor Tensor (P < .05).ConclusionSurgeons should consider the discrepancy in assessing intraoperative soft tissue balance depending on the tensor used. The Ligament Sensor Tensor tended to underestimate soft tissue balance in CR and PS TKAs compared with the Offset Repo-Tensor, especially in PS TKA. Thus, surgeons should know the difference in values between the offset-type tensor with consistent distraction force and a spring-loaded tensor.     

Characteristic kinematics of floor-sitting activities after posterior-stabilized total knee arthroplasty determined using model-based shape-matching techniques

BackgroundDetailed kinematics of floor-sitting activities after total knee arthroplasty (TKA) have not been well explored. Knee kinematics of cross-legged sitting, seiza-sitting, and side-sitting after TKA were examined to clarify the differences in tibiofemoral kinematics of each activity.MethodsSubjects were 40 knees in 20 osteoarthritic patients who underwent bilateral TKA with a high-flexion fixed-bearing posterior-stabilized prosthesis. Dynamic radiographs of floor-sitting activities were taken, and the knee kinematics were compared among the three activities. The patients were also divided into two groups (possible/easy group and impossible/no-try group) for each activity, and group comparisons were conducted.ResultsThe maximum implant flexion angle was significantly greater in seiza-sitting. In valgus/varus rotation, seiza-sitting demonstrated neutral rotation, while cross-legged sitting showed varus of about 10°, and side-sitting exhibited valgus. In tibial internal/external rotation, seiza-sitting demonstrated a constant rotational angle, while cross-legged sitting showed tibial internal rotation with flexion, and side-sitting exhibited tibial external rotation with flexion. The kinematic pathway during deep flexion illustrated the medial pivot pattern in cross-legged sitting, a small amount of bicondylar rollback in seiza-sitting, and the weak lateral pivot pattern in side-sitting. A greater flexion angle was the important factor for the performance of each floor-sitting activity followed by varus laxity at 10° knee flexion.ConclusionsThis study successfully revealed characteristic kinematic patterns of TKA knees in three floor-sitting activities. Obtaining a greater knee flexion with adequate lateral laxity is the key to enhancing postoperative floor-sitting activities.     

The effect of knee prosthesis design on tibiofemoral biomechanics during extension tasks following total knee arthroplasty

BackgroundDetermine whether the tibiofemoral motion and electromyographic activity of the knee differs in patients with a medial pivot implant, compared to those with cruciate-retaining and posterior-stabilised designs, during knee extension after Total Knee Arthroplasty (TKA).MethodsAn observational study was conducted on a cohort of patients that had undergone TKA for a minimum of 12 months prior. Three matched groups (n = 18) were categorised based on implant type: medial-pivot (MP), posterior-stabilised (PS) and cruciate-retaining (CR). Kinematics, with motion analysis (Vicon, USA) and surface electromyography (Delsys, USA) were assessed during step-ascent and walking tasks.ResultsAll groups displayed a similar amount of knee extension in both tasks. They also paradoxically produced an average mean internal rotation movement during knee extension in both the step-ascent and walking tasks. The only significant difference was found in the step-ascent task, in which the MP group produced a larger absolute amount of rotation than the CR implant group (P = 0.007), but neither group differed from the PS implant group. The groups did not differ in rotation during the walking task (P > 0.05). The MP group displayed significantly (P < 0.01) greater knee extensor activation during the step-ascent than the PS group.ConclusionThe MP design was only significantly different to another implant design for the step-ascent task. Patients with either knee implant types were not strictly limited to producing the traditional “screw-home” mechanism, defined by external rotation during extension. Furthermore, comparison with the non-implant contralateral limb suggested that rotation is not necessarily dictated by implant design.