Effects of posterior condylar offset and posterior tibial slope on mobile-bearing total knee arthroplasty using computational simulation

Background

Postoperative changes of the femoral posterior condylar offset (PCO) and posterior tibial slope (PTS) affect the biomechanics of the knee joint after fixed-bearing total knee arthroplasty (TKA). However, the biomechanics of mobile-bearing is not well known. Therefore, the aim of this study was to investigate whether alterations to the PCO and PTS affect the biomechanics for mobile-bearing TKA.

活动平台单髁膝关节置换胫骨后倾的有限元分析

背景：目前单髁膝关节置换中胫骨假体后倾角度的选择存在较多争议,相关的生物力学研究较少。 目的：通过有限元分析结果寻求活动平台单髁膝关节置换中合理胫骨后倾的角度。 方法：运用三维重建技术及有限元前处理技术建立正常膝关节有限元模型,并进行验证,在此基础上建立不同胫骨假体后倾角度的单髁膝关节置换有限元模型,统一边界条件和载荷,行有限元分析。 结果与结论：成功建立了不同胫骨后倾角度的单髁膝关节置换有限元模型,分析结果发现增大胫骨假体后倾可使胫骨后内侧皮质及松质骨应力逐渐增加,且增大了外侧间室载荷和软骨接触应力,而胫骨前倾使胫骨前内侧皮质应力明显增加。推荐活动平台单髁膝关节置换中选择0°-7°胫骨假体后倾。 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

单髁置换术应用于骨关节炎合并前交叉韧带缺失的三维有限元研究

目的采用有限元方法比较前交叉韧带(anterior cruciate ligament,ACL)完整与缺失的骨关节炎患者单髁关节置换(unicompartmental knee arthroplasty,UKA)术后膝关节生物力学特性,分析ACL缺失对膝关节单髁置换术后的运动和应力的影响。方法根据膝关节CT、MRI图像,建立有限元模型。采用逆向工程技术重建活动衬垫单髁假体,加载入该正常膝关节三维有限元模型。在不同屈膝角度(0°、30°、60°、90°、120°)加载载荷,观察在ACL完整(ACL-intact,ACLI)和缺失(ACL-deficiency,ACLD)情况下,膝关节的最大接触压和位移程度。结果 UKA-ACLI与UKA-ACLD模型在膝关节屈膝各角度,各部位(外侧股骨软骨、胫骨软骨、半月板、股骨假体、胫骨假体、衬垫)最大应力无明显差异,ACLD模型在膝关节屈膝0°和30°位前后位移明显大于ACLI模型,在膝关节屈膝0°位股骨相对内旋减小,在膝关节屈膝30°位股骨相对外旋增加。结论标准位置假体植入情况下,ACL缺失并不会导致UKA术后应力异常增大,会导致在膝关节伸直位时位移增加。     

Proximal tibial morphology is associated with risk of trauma to the posteromedial structures during tibial bone resection reproducing the anatomical posterior tibial slope in bicruciate-retaining total knee arthroplasty

BackgroundA tibial cut with the native posterior tibial slope (PTS) is a theoretical prerequisite in bicruciate-retaining total knee arthroplasty (BCRTKA) to regain physiological knee kinematics. The present study reveals tibial morphological risk factors of trauma to the posteromedial structures of the knee during tibial bone resection in BCRTKA.MethodsFifty patients undergoing BCRTKA for varus knee osteoarthritis were analyzed. A three-dimensional tibial bone model was reconstructed using a computed tomography-based preoperative planning system, and the coronal tibial slope (CTS) and medial PTS (MPTS) were measured. Then, we set the simulated tibial cutting plane neutral on the coronal plane, posteriorly inclined in accordance with the MPTS on the sagittal plane, and 9 mm below the surface of the subchondral cortical bone (i.e., 11 mm below the surface of the cartilage) of the lateral tibial plateau. The association between the tibial morphology and the distance from the simulated cutting plane to the semimembranosus (SM) insertion (Dsm) was analyzed.ResultsOf the 50 patients, 19 (38%) had negative Dsm values, indicating a cut into the SM (namely, below the posterior oblique ligament) insertion. The MPTS was negatively correlated with Dsm (r = −0.396, p = 0.004), whereas the CTS was positively correlated with Dsm (r = 0.619, p < 0.001). On multivariate linear regression analysis, the MPTS and CTS were independent predictors of Dsm.ConclusionIn the setting of tibial cuts reproducing the native MPTS in BCRTKA, patients with larger PTS and smaller CTS had more risk of trauma to the posteromedial structures.     

Relationship between posterior tibial slope and rotation on axial alignment in total knee arthroplasty

Posterior tibial slope can help to decrease ligament tension during flexion in total knee arthroplasty. External rotation of the tibial component has also been advocated to facilitate patellar tracking. However, combined anteroposterior inclination and rotation can produce a change in axial alignment. A mathematical model was used to determine the relationship between tibial slope and rotation on axial alignment. Posterior slope of 10° and rotation of the tibial cut of 6° changes axial alignment by slightly > 1°. If a sloped tibial cut is internally rotated, slight valgus will occur. If a sloped tibial cut is externally rotated, slight varus will occur. If the tibial cut is sloped posteriorly and the cut or component is rotated, a change in axial alignment of the limb can occur. Malrotation of a sloped tibial cut should be avoided and when rotational position of the prosthesis is determined by inserting trial components, an assessment of limb alignment should be made before implanting the final components.     

单髁与后交叉韧带保留型假体膝关节置换的近期疗效对比

文题释义： 单髁置换：指对仅存在单间室病变膝关节的一种置换手术方式,用以替代膝关节胫股关节破坏的软骨表面,具有微创手术的优势,例如创伤小、恢复快、截骨少、费用低、手术时间短等优点。理论上,单髁置换后患者的膝关节活动度较好,且膝关节功能接近生理状态。 后交叉韧带保留型假体：全膝关节置换术中一种较为成熟的假体,术中保留了膝关节后交叉韧带且不进行髁间窝截骨,比较符合膝关节的解剖特性,手术难度虽然较大,但保留了较多的膝关节正常生理结构,有较好的膝关节稳定性,假体的松动率亦较低。背景：针对仅存在膝关节内侧间室病变的患者,单髁置换与后交叉韧带保留型全膝关节置换均是有效的治疗方式,但对于居住于山区的中老年人的近期疗效需进一步探索。 目的：探讨单髁置换与后交叉韧带保留型假体置换治疗承德地区中老年人膝关节内侧间室骨关节炎的近期疗效。 方法：选择2017年1月至2019年2月在承德医学院附属医院关节外科接受手术治疗的内侧间室膝关节炎中老年患者67例,其中A组31例行单髁置换,B组36例行后交叉韧带保留型假体全膝置换。所有患者对治疗方案均知情同意,且得到医院伦理委员会批准。观察比较2组患者术中出血量、术后输血情况、术后血红蛋白下降值,术后1,3 d红细胞容积、C-反应蛋白,术后第1,3,6个月及1年的关节遗忘评分。 结果与结论：①A组围术期血红蛋白下降值、术中出血量、输血率均低于B组,术后住院时间短于B组,差异有显著性意义(P < 0.05);②术后第1,3天2组的C-反应蛋白水平差异无显著性意义(P > 0.05);③A组术后第1,3,6月及1年的关节遗忘评分均高于B组,差异有显著性意义(P < 0.01);④2组术后均未发生下肢深静脉血栓、肺栓塞及感染等并发症;⑤综上,单髁置换在治疗仅存在内侧间室病变膝关节炎的山区中老年患者时,具有术中出血少、输血率低、关节遗忘程度高等优点。 ORCID: 0000-0002-8983-8293(韩梦光) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Effect of tibial component overhang on survivorship in medial mobile-bearing unicompartmental knee arthroplasty

BackgroundSome studies have shown that the position of the tibial component in Oxford unicompartmental knee arthroplasty with a mobile bearing will affect the clinical outcome of patients. Hence, our study aimed to investigate the relationship between the overhang distance of the tibial component and the survival of the implant.MethodsA retrospective analysis of patients who underwent unicompartmental knee arthroplasty at the same institution from 2014 to 2018 was presented. The study was divided into three groups: minor underhang group (underhang between −3 and 0 mm); minor overhang group (overhang 0–3 mm); and major overhang group (overhang ≥ 3 mm). Demographic and clinical profile characteristics of each group were compared, and survival curves of each group were also compared using Kaplan–Meier and modeled using multivariate Cox regression.ResultsA total of 351 knees were included in this study with a minimum follow up of three years and a mean follow up of 4.8 ± 1.5 years. The revision rates in each group were 3.6% (minor underhang group), 2.7% (minor overhang group), and 20.9% (major overhang group) (P < 0.001). From the three groups’ cumulative survival rates, the major overhang group was significantly lower than the other two groups (log rank P < 0.001). Multivariate Cox regression showed an association between the major overhang group and implant survival rate (hazard ratio = 7.515, 95% confidence interval = 2.500–22.593, P < 0.001)ConclusionThe risk of revision will increase if the tibial component overhangs more than 3 mm medially. Moreover, the reasons for revision are generally bearing dislocation and aseptic loosening.     

Interactive effect of femoral posterior condylar offset and tibial posterior slope on knee flexion in posterior cruciate ligament-substituting total knee arthroplasty

Background

This work aimed to evaluate the changes in the femoral posterior condylar offset (PCO) and tibial slope after posterior cruciate ligament (PCL)-substituting total knee arthroplasty (TKA), and to address the presence of any interactive effect between the two on knee flexion.

Effect of femoral component position on biomechanical outcomes of unicompartmental knee arthroplasty

Background

The positions of unicompartmental femoral components do not always follow the neutral center of the medial distal femoral condyle. The biomechanical effect of the center of the distal femoral condyle has not yet been evaluated, and the optimal femoral position in unicompartmental knee arthroplasty (UKA) is yet to be biomechanically justified. The purpose of this study was to evaluate, using finite element analysis, the effect of the center of the distal femoral component on the biomechanical outcomes of UKA with respect to the contact stresses in the polyethylene (PE) insert and articular cartilage.

Influence of tibial component rotation on short-term clinical outcomes in Oxford mobile-bearing unicompartmental knee arthroplasty

Background

Malposition of tibial components is an important factor for complications in unicompartmental knee arthroplasty (UKA), but the direct relationship between clinical outcomes and position of tibial component remains unknown. We aimed to investigate whether tibial component rotation in the axial plane could affect clinical outcomes after UKA.

机器人辅助下膝关节单髁置换术初步临床结果

目的 探讨机器人辅助下膝关节单髁置换术(UKA)能否提高手术的精准性,以及其安全性和短期疗效。方法 对2016年9—12月在上海交通大学附属第六人民医院和解放军总医院骨科关节外科接受机器人辅助下UKA治疗的20例患者临床资料进行回顾性分析。术前诊断均为膝关节骨关节炎,每家医院各10例患者;男3例,女17例;年龄51~79岁,平均65岁;BMI(26.9±3.4) kg/m²。均采用MAKO RIO机器人手术系统和RESTORIS MCK单髁膝关节假体(STRYKER MAKO Surgical,美国)进行手术,其中有5例患者同时接受双侧UKA。记录手术时间及出血量、术后疼痛情况,测量术前及术后下肢力线、术后胫骨假体植入角度,术前和术后进行膝关节功能评分。结果 单侧UKA手术术中止血带使用时间平均为(27±10) min。15例单侧单髁置换患者术后第2天时总失血量平均为(476±290)mL,无一例患者需要接受输血治疗。术后8、16和24 h VAS评分平均分别为(3.2±1.2)分、(1.8±0.8)分和(1.1±0.3)分。20例(25膝)患者均获得随访,随访时间为8~20周,平均14.1周。末次随访时,患侧膝关节的美国膝关节协会评分临床评分由术前的(57±13)分提高至(90±6)分,功能评分由术前的(48±18)分提高至(79±12)分,差异均有统计学意义(t=14.941、10.014,P值均<0.01);胫骨假体冠状位的植入角度为内翻0°~3.9°,平均1.7°±1.2°,与术前计划的目标角度(内翻1°)偏差0°~3°,平均为1.1°±0.9°。2家医院两组病例胫骨假体冠状位角度与目标位置的偏差分别为1.2°±1.1°和1.0°±0.6°,差异无统计学意义(t=0.421, P＞0.05)。随访期间所有病例均未观察到手术部位感染、深静脉血栓形成以及血管神经损伤等手术相关的并发症。结论 机器人辅助下UKA能够实现微创条件下的精准手术,并具有优异的安全性;其远期临床效果及对膝关节功能改善的作用,尚需进一步的对照研究和长期随访加以证实。     

单髁置换与全膝关节置换后隐性失血的对比研究

文题释义： 隐性失血：一般是指较大的创伤或手术后,排除手术创面失血、术中及术后引流丢失等可计算的显性失血之外,患者机体内丢失的血量。试验中由于所有患者术后均未放置引流管,未观察到显性失血,所以术后第4,21,42天的总失血量为隐性失血量,用血红蛋白和红细胞比容数值变化来体现隐性失血的变化。 显性失血：一般是指较大的创伤或者手术后,手术创面失血、术中及术后引流丢失等可计算的失血量。 背景：单髁置换相较于全膝关节置换的术中失血量相比较低,但二者之间的术后隐性失血量差异尚未得到广泛研究。 目的：对比单髁置换与全膝关节置换后隐性失血的差异,分析术前贫血患者是否也可以在无输血风险的情况下进行单髁置换手术。 方法：选择2014年1月至2016年12月联勤保障部队第904医院收治的膝关节骨性关节炎患者148 例,其中58例进行单髁置换手术,90例进行全膝关节置换手术。术前及术后第1,4,21,42天,检测两组血红蛋白水平、红细胞比容,计算隐性失血量与输血率。试验获得联勤保障部队第904医院伦理委员会批准,批准号：2019-01-03。 结果与结论：①单髁置换组术后第1,4天的血红蛋白水平高于全膝关节置换组(P < 0.01),两组术前及术后21,42天的血红蛋白水平比较差异无显著性意义(P > 0.05);②单髁置换组术后第1,4天的红细胞比容高于全膝关节置换组(P < 0.01),两组术前及术后21,42天的红细胞比容比较差异无显著性意义(P > 0.05);③在术后第1,4天之间,单髁置换组中女性没有隐性失血,男性平均血红蛋白下降量为 4 g/L;全膝关节置换组中女性平均血红蛋白下降量为 10 g/L,男性为 7 g/L,单髁置换组男性与女性的隐性失血量均低于全膝关节置换组的对应性别患者(P < 0.05或P < 0.01);④单髁置换组的输血率为0%,全膝关节置换组的输血率为4.4%;术前中度贫血的患者(血红蛋白60-89 g/L),单髁置换组3例均无需输血,而全膝关节置换组6例中2例(33%)需输血;⑤结果表明,单髁置换较全膝关节置换在术后隐性失血方面有明显优势。 ORCID: 0000-0002-7314-5548(彭超) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Influence of cartilage and menisci on the sagittal slope of the tibial plateaus

We analyzed the magnetic resonance studies of the knee in 80 subjects, 45 men and 35 women with a mean age of 38.9 years, who showed no pathological condition of the joint. Using an imaging visualization software, the sagittal longitudinal axis of the tibia was identified. The angle between this axis and a line tangent to the bone profile of the tibial plateau (bone slope) and to the superior border of the menisci (meniscal slope) were calculated. Thickness of anterior and posterior portion of menisci and underlying cartilage were also measured. The bone slope averaged 8° and 7.7° on the medial and lateral sides, respectively. The mean meniscal slope was 4.1° and 3.3° on the medial and lateral sides, respectively, with a significant difference compared with the bone slope. Menisci and underlying cartilage were significantly thicker in their posterior than their anterior portion (7.6 and 5.2 mm, respectively, in the medial compartment; 8.6 and 5.2 mm, respectively, in the lateral compartment). The presence of cartilage and menisci implies a significant decrease in the posterior tibial slope. In the lateral compartment, the greater the bone slope, the larger the difference between bone and meniscal slope, which means that a marked posterior tilt of the lateral tibial plateau is decreased by the cartilage and meniscus. These findings should be taken into account in planning surgical procedures which affect the slope of the articular tibial surface. Clin. Anat. 26:883–892, 2013. © 2012 Wiley Periodicals, Inc.     

Correlation between posterior offset of femoral condyles and sagittal slope of the tibial plateau

The aim of this study was to address, in normal knees, the variability of posterior offset of femoral condyles and tibial slope, and the presence of any correlation between the two that might be needed to achieve an adequate joint motion in flexion. Magnetic resonance images of normal knees of 80 subjects, 45 males and 35 females, with a mean age of 38.9 years, were analysed. Measurements were performed by two independent observers using an imaging visualization software. The tibial slope averaged 8 and 7.7 °, on the medial and lateral sides, respectively (P = 0.2); the mean posterior offset of femoral condyles was 27.4 and 25.2 mm on the two sides, respectively (P = 0.0001). The variation coefficient of the condylar offset and tibial slope was 11.5 and 38%, respectively. In the medial compartment, a significant correlation was found between the femoral condylar offset and the tibial slope, while the same was not observed in the lateral compartment of the knee. Magnetic resonance imaging allows the assessment of tibial slope and femoral condylar offset in the medial and lateral side separately, taking into account any difference between the two compartments. The sagittal tibial slope exhibits a greater variability compared with the posterior offset of femoral condyles. The correlation found, in the medial compartment, between the tibial slope and femoral condylar offset suggests that the reconstitution of the proper morphology of the posterior part of the knee joint may be necessary to obtain a full range of motion in flexion after total knee replacement.     

The patient perspective,experience and satisfaction of day case unicompartmental knee arthroplasty: A short-term mixed-methods study

BackgroundDay case unicompartmental knee arthroplasty (UKA) is increasingly being performed worldwide. When performed in the appropriate patient, day case UKA has been demonstrated to be safe, cost effective and improve resource allocation. Limited evidence highlights increased patient satisfaction of day case UKA when compared with inpatient UKA. A detailed study of the patient perspective, experience and satisfaction following day case UKA has not been described before.MethodsA retrospective case series review of 21 consecutive patients (19 unilateral, 2 bilateral) undergoing day case UKA in an elective orthopaedic centre was undertaken. A qualitative and quantitative patient assessment of the day case UKA experience was administered. A five-point Likert scale satisfaction questionnaire, Oxford Knee Score (OKS) and open-ended interview was undertaken. The qualitative responses underwent thematic analysis.ResultsOne hundred percent of patients expressed satisfaction (76.2% completely satisfied, 33.8% moderately satisfied) with day case UKA. The majority of patients (90.5%) reported that if they had to undergo UKA again they would prefer a day case over an inpatient procedure. Patients consider surgical outcome, physiotherapy provision, discharge planning, postoperative medications and follow up as key aspects of day case UKA care. One patient was re-admitted following discharge.ConclusionsThe present study demonstrates a high level of patient satisfaction with day case UKA. The results reported herein are subject to the study limitations of sample size, recall bias and inclusion criteria. We recommend that the themes identified by patients are addressed through a multidisciplinary approach with well-defined clinical pathways for a high-quality patient-centred experience.     

Impact of joint line orientation on clinical outcomes in bilateral Oxford mobile-bearing unicompartmental knee arthroplasty

BackgroundJoint line orientation angle (JLOA) is the angle between the knee joint line and the floor. It has been reported to be related to postoperative outcome after TKA. Regarding unicompartmental knee arthroplasty (UKA), although it can be horizontal after UKA because it is a resurfacing surgery, there are few reports about the JLOA after UKA and its impact on clinical outcomes.PurposeThe purpose of this study was to reveal the relationship between JLOA and clinical outcome after UKA.MethodsThis study included 106 knees in 53 consecutive patients with osteoarthritis who underwent simultaneous bilateral mobile-bearing UKA. Their pre- and postoperative JLOAs were measured by full-leg-length standing coronal radiographs. We also evaluated the tibial component height (TCH) as the factor which we assumed could influence JLOA. We analyzed the patients’ JLOAs, TCHs and clinical outcomes.ResultsPre- and postoperative JLOA were 0.4 ± 2.4° and 2.7 ± 2.6°, respectively. The JLOA significantly tilted medially (P < 0.0001). The JLOA significantly negatively correlated with the improvement of the clinical outcomes (Oxford Knee Score (OKS): r = 0.40, P < 0.0001, Knee Society Knee Score (KSKS): r = 0.25, P < 0.01, Knee Society Function Score (KSFS): r = 0.22, P = 0.02). The TCH showed a positive correlation with postoperative JLOA and with the postoperative JLOA change (r = 0.45, P < 0.001; r = 0.25, P < 0.01, respectively).ConclusionThe JLOA significantly tilted medially after UKA. An excessive medial tilt of the JLOA was associated with poorer postoperative outcomes of UKA. It is therefore recommended to keep the JLOA horizontal and to avoid a lower tibial cut.     

膝关节单髁置换三维参数化建模

背景：用于外科训练和演练的单髁假体模型因尺寸和特征固定而无法满足个体患者的实际需求。 目的：为膝关节单髁置换的数字化研究提供一种三维参数化建模方法。 方法：运用三维重建技术建立膝关节炎三维模型,然后通过参数化软件Pro/Engineer 5.0设计与骨性模型相匹配的单髁假体,最后模拟膝关节单髁置换并进行三维有限元分析。 结果与结论：三维参数化建模法效率高,实现了膝关节单髁假体设计的自动化和高效化,所建模型形态逼真,精确度高。三维参数化建模法为膝关节单髁置换的生物力学研究提供了模型基础和新的实验思路。     

活动和固定平台单髁置换术的临床应用进展

单髁置换术(UKA)是指治疗单一间室膝骨关节炎(KOA)的一种微创手术,因其具有手术切口小、术中出血少、术后恢复快等优势,逐渐成为膝骨关节炎阶梯化治疗中的重要环节.临床上应用的UKA假体主要有活动平台(MB)和固定平台(FB)两种,MB-UKA可使膝关节的运动更接近自然生物力学且磨损率低,但易发生垫片脱位及假体撞击等并...     

第四代Oxford单髁置换术对膝关节内侧间室骨关节炎患者的疗效评估及步态分析

目的探讨第四代Oxford单髁置换术对膝关节内侧间室骨关节炎患者的临床疗效及对患者步态恢复的影响。方法将2016年1月至2018年1月收治并符合标准的30例(30膝)膝关节内侧间室骨关节炎患者纳入研究并作为试验组,另外再纳入20例(20膝)膝关节正常的志愿者作为本研究的正常组。试验组患者接受第四代Oxford单髁置换术,正常组研究对象不做任何治疗干预,仅作为观测指标对照。本研究观测指标主要包括疼痛视觉模拟评分(VAS评分)、膝关节学会评分系统(KSS)、美国WOMAC骨关节炎指数评分、美国特种外科医院膝关节评分(HSS评分)和步态分析运动学参数。比较试验组在术前、术后6个月及术后12个月的观测指标的差异,并分别与正常组作比较。结果试验组患者术前、术后6个月及术后12个月3个时间段两两之间的VAS评分、HSS评分、WOMAC评分以及KSS评分比较,差异均具有统计学意义(0.05)。试验组患者术前、术后6个月及术后12个月的步态分析各运动学参数的差异均具有统计学意义(0.05)。其中除最大前位移和最大内位移在术后6个月及术后12个月两个时间段差异无统计学意义之外,其他步态分析各运动学参数在3个时间段两两之间差异均具有统计学意义(0.05);试验组患者在术后12个月与正常组步态分析各运动学参数相比,最大伸直角、最大内位移和最大外位移比较,差异无统计学意义(0.05),但其余各步态分析各运动学参数差异仍然存在统计学意义(0.05)。结论在选择适当的病例和严格掌握手术适应证的前提下,第四代Oxford单髁置换术对膝关节内侧间室骨关节炎患者的近、中期疗效满意,术后患者关节功能更接近生理状态。     

Instrumented gait analysis in patients with medial osteoarthritis of the knee after mobile-bearing unicompartmental knee arthroplasty

Background

Unicompartmental knee arthroplasty (UKA) is an effective treatment for patients with medial osteoarthritis of the knee joint. Instrumented gait analysis provides an objective measure to quantify and qualify postoperative changes of gait. The purpose of this study was to evaluate standardized instrumented gait analysis for functional recovery and gait as an outcome of mobile-bearing UKA in patients with medial osteoarthritis of the knee.