Obtaining anatomic motion and laxity characteristics in a total knee design

BackgroundSince the introduction of the first total knee designs, a frequent design goal has been to reproduce normal knee motion. However, studies of many currently used total knee designs, have shown that this goal has not been achieved. We proposed that Guided Motion total knee designs, could achieve more anatomic motion than present standard designs.MethodsSeveral Guided Motion knees for application without cruciate ligaments were designed using a computer method where the bearing surfaces were generated by the motion required. A knee testing machine was constructed where physiological forces including compressive, shear and torque were applied during knee flexion. The neutral path of motion and the laxity about the neutral path were measured. This evaluation method was a modification of the ASTM standard Constraint Test.ResultsThe motions of the Guided Motion knees and a standard PS knee were compared with the anatomic motion of knee specimens determined in an earlier study The Guided Motion knees showed motion patterns which were closer to anatomic than the PS knee.ConclusionsThe results provided justification for carrying out further evaluations of functional conditions, using either knee simulators or computer modelling. If anatomic motions could be reproduced in vivo, it is possible that clinical outcomes could be improved.     

Laxity and contact forces of total knee designed for anatomic motion: A cadaveric study

Background

Total knee designs that attempt to reproduce more physiological knee kinematics are gaining attention given their possible improvement in functional outcomes. This study examined if a total knee designed for anatomic motion, where the soft tissue balancing was intended to replicate anatomical tibiofemoral contact forces, can more closely reproduce the laxity of the native knee.

Intra-operative navigation of knee kinematics and the influence of osteoarthritis

Intra-operative assessment of knee kinematics should optimise implantation of total knee arthroplasties. The purpose of this work was to validate the data delivered by an adapted navigation system in 10 healthy cadaver knees and to investigate the kinematics of 10 osteoarthritic (OA) knees in patients undergoing total knee replacement. The system displayed the magnitude of axial rotation, the position of the instantaneous centre of axial rotation and the displacements of the condyles. Successive cycles from full extension to 140° of flexion in the same knee produced a mean external rotation of 20° ± 10°, which was correlated to knee flexion (r=0.6 ± 0.2 in healthy knees, r=0.8 ± 0.2 in OA knees). The centre of axial rotation migrated posteriorly an average of 8.2mm in both groups. The posterior displacements were 4 mm ± 5 mm in healthy and 5 mm ± 6 mm in OA knees for the medial condyle, and 21 mm ± 9 mm in healthy and 21 mm ± 10 mm in OA knees for the lateral condyle. The medial condyle lifted off beyond 110° of flexion. Results in healthy knees were consistent with those reported in the current literature. The kinematics of healthy and of OA knees with an intact anterior cruciate ligament did not differ significantly.     

A mid-term clinical outcome study of the Advance Medial Pivot knee arthroplasty

The Advance Medial Pivot Total Knee Arthroplasty (Wright Medical Technology, Arlington, Tennessee, USA) has been designed to reproduce modern ideas of knee kinematics. We report a prospective clinical outcome study of 284 arthroplasties in 225 consecutive patients with a mean follow-up of 6.7 years (range 4 to 9 years). For evaluation, both objective and subjective clinical rating systems and serial radiographs were used. At final follow-up, 10 (4.4%) patients (10 knees) only were lost from follow-up and four (1.8%) patients (five knees) had died for reasons unrelated to the surgery with their knees performing well. There was an 82% compliance in the intervals of follow-up evaluation. All patients showed a statistically significant improvement (p = 0.01) in the Knee Society clinical rating system, WOMAC questionnaire, SF-12 questionnaire, and Oxford knee score. The majority of patients (92%) were able to perform age-appropriate activities with a mean knee flexion of 117° (range 85° to 135°) at final follow-up. Survival analysis showed a cumulative success rate of 99.1% at 5 years. Two (0.7%) arthoplasties, in which patient selection and surgical errors were identified, were revised due to aseptic loosening, one due to infection and one due to a traumatic dislocation. This study demonstrates satisfactory mid-term clinical results for this knee design.     

The influence of polyethylene bearing thickness on the tibiofemoral kinematics of a bicruciate retaining total knee arthroplasty

Background

The recently reintroduced bicruciate retaining Total Knee Arthroplasty (BCR TKA) is an effort to reproduce kinematics closer to the native knee. However, there is no data on appropriate balancing with this implant. Balancing is crucial and challenging as medial and lateral polyethylene (PE) inlays are modular, which allows for placement of different thicknesses in the medial and lateral compartments. This study aimed at providing a detailed kinematic view on balancing BCR TKA.

CR假体与PS假体全膝关节置换治疗膝骨性关节炎合并膝外翻畸形的疗效分析

目的 比较后交叉韧带保留型（CR）假体与后方稳定型（PS）假体行人工全膝关节置换术（TKA）治疗膝骨性关节炎合并膝外翻畸形的临床疗效。方法 回顾性分析南昌大学附属赣州医院关节外科2019年5月至2021年5月收治的60例（60膝）膝骨性关节炎合并膝外翻畸形患者资料,均为单侧置换。30例采用CR假体行TKA治疗（CR组）,30例采用PS假体行TKA治疗（PS组）。比较两组患者的手术时间、术中失血量、术后引流量、术后3 d血红蛋白（Hb）下降量及深静脉血栓发生情况;比较两组患者手术前后膝外翻角;比较两组患者术后1周、1个月、3个月、6个月、1年疼痛视觉模拟评分（VAS）、膝关节活动度（ROM）、美国特种外科医院膝关节评分（HSS）。结果 60例患者均顺利完成TKA手术,所有患者随访13 ～ 28个月,平均（18.51±0.90）个月。CR组术中出血量、术后引流量、术后3 d的Hb下降量较PS组减少（P＜0.05）;两组手术时间相当、术后均无深静脉血栓发生,差异无统计学意义（P＞0.05）;两组手术前后膝外翻角的比较差异无统计学意义（P＞0.05）;CR组术后1周、1个月VAS评分较PS组更低（P＜0.05）,两组术后3个月、6月、1年VAS评分比较差异无统计学意义（P＞0.05）;CR组术后1周、1个月、3个月膝关节ROM和HSS评分优于PS组（P＜0.05）,两组术后6个月、1年膝关节ROM和HSS评分比较差异无统计学意义（P＞0.05）。结论 采用CR或PS假体行TKA手术治疗膝骨性关节炎合并膝外翻畸形均可有效纠正膝关节畸形、减轻膝关节疼痛、改善膝关节活动度及功能,取得满意临床疗效;但相对PS假体,CR假体保留了后交叉韧带,减少了股骨髁部截骨量,从而减少手术出血,更好减轻早期术后疼痛,有助于TKA术后早期功能康复。     

Functional knee apparatus for the evaluation of ligamentous tensions on contact loads

BackgroundSoft tissue balancing is integral in providing stability following total knee arthroplasty (TKA). Although intraoperative contact load sensors are providing insights into the effects of soft tissue balancing, there is still a lack of understanding of the relationship between the knee’s ligamentous tensions and joint surface contact loads. This study reports on the development of a multifunctional testing apparatus that can quantify the effects of ligamentous tension on joint contact loads in a controlled repeatable environment.MethodsThe functional knee apparatus was constructed to act as an anatomical substitute for the benchtop assessment of intraoperative soft tissue balancing. The system was calibrated through reproduction of results from a cadaveric study that employed intraoperative load sensors. Experimentation was then conducted to quantify the effects of tensile pretension variation on measured contact loads throughout the full range of flexion.ResultsA linear relationship between the ligamentous tensions and contact loads was observed, with ligaments contributing to 74–80% of the measured contact loads. Ligamentous tensions could be approximated from measured contact loads to within ± 23 N.ConclusionThe proposed apparatus can prove to be a valuable tool in the continued exploration of currently undocumented effects (e.g. surgical alteration) in soft tissue balancing. In addition to quantifying the relationship between ligamentous tensions and joint contact loads, soft tissue loading conditions where bicondylar contact was lost (i.e. known sign of kinematic instability) were identified. As a corollary, this system may be able to provide insights on soft tissue balancing standards predictive of patient outcomes.     

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。     

Translational and rotational knee joint stability in anterior and posterior cruciate-retaining knee arthroplasty

This study investigated passive translational and rotational stability properties of the intact knee joint, after bicruciate-retaining bi-compartmental knee arthroplasty (BKA) and after posterior cruciate retaining total knee arthroplasty (TKA). Fourteen human cadaveric knee specimens were used in this study, and a robotic manipulator with six-axis force/torque sensor was used to test the joint laxity in anterior–posterior translation, valgus–varus, and internal–external rotation. The results show the knee joint stability after bicruciate-retaining BKA is similar to that of the native knee. On the other hand, the PCL-retaining TKA results in inferior joint stability in valgus, varus, external rotation, anterior and, surprisingly, posterior directions. Our findings suggest that, provided functional ligamentous structures, bicruciate-retaining BKA is a biomechanically attractive treatment for joint degenerative disease.     

Assessment of the antero-posterior and rotational stability of the anterior cruciate ligament analogue in a guided motion bi-cruciate stabilized total knee arthroplasty

Abnormal knee kinematics and sagittal instability after most knee replacements are due in part to deficient anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) function. The guided motion bi-cruciate stabilized knee replacement aspires to stabilize the knee posteriorly and anteriorly by means of a cam-post mechanism. This investigation studies the ACL-stabilizing function of that mechanism in early flexion, and 25 knees that had undergone replacement with this implant were studied. Antero-posterior laxity at 15° flexion was adequately restored for 76% (16/21) of the knees (side-to-side difference <3?mm on KT assessment), and 72% (18/25) knees exhibited a positive pivot shift test. The findings of this study suggest excellent early clinical outcomes for this implant, but the goal of replicating ACL function has only been partially achieved.     

Analysis of the factors that correlate with increased knee adduction moment during gait in the early postoperative period following total knee arthroplasty

Background

Analysis of dynamic knee loading during gait is essential to prevent mechanical failures following total knee arthroplasty. External knee adduction moment during gait is the primary factor producing medial joint reaction force, and an increase in the moment is directly related to an increase in the medial compartment load on the knee.

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...     

Reference axes for reconstruction of the knee

Knee alignment is an essential problem in reconstructive surgeries of the knee. Quite a number of reference parameters have been suggested to help the surgeons to get proper alignment during operations. In this article, most commonly used reference axes, both for the axial and the rotational, are reviewed, in an attempt to highlight their reliabilities and clinical relevance.     

Recognizing knee pathologies by classifying instantaneous screws of the six degrees-of-freedom knee motion

We address the problem of knee pathology assessment by using screw theory to describe the knee motion and by using the screw representation of the motion as an input to a machine learning classifier. The flexions of knees with different pathologies are tracked using an optical tracking system. The instantaneous screw parameters which describe the transformation of the tibia with respect to the femur in each two successive observation is represented as the instantaneous screw axis of the motion given in its Plücker line coordinates along with its corresponding pitch. The set of instantaneous screw parameters associated with a particular knee with a given pathology is then identified and clustered in R ⁶ to form a “signature” of the motion for the given pathology. Sawbones model and two cadaver knees with different pathologies were tracked, and the resulting screws were used to train a classifier system. The system was then tested successfully with new, never-trained-before data. The classifier demonstrated a very high success rate in identifying the knee pathology.

Intraoperative kinematics of bicruciate-stabilized total knee arthroplasty during high-flexion motion of the knee

BackgroundIt is unknown whether intraoperative kinematics of bicruciate-stabilized total knee arthroplasty (BCS-TKA) are different for different activities. It has also not been established whether intraoperative high-flexion motions correlate with postoperative patient-reported outcome measures (PROMs). We aimed to clarify the intraoperative kinematics of BCS-TKA during high-flexion activities and describe the relationship between intraoperative and postoperative patient-reported outcomes.MethodsWe examined 33 knees from 31 patients who underwent BCS-TKA and measured intraoperative knee kinematics, passive knee flexion, and cross-legged flexion using a navigation system. We also calculated knee flexion, varus-valgus, and rotation angles. As a secondary evaluation, we divided the patients into two clusters based on the PROMs and compared the kinematics between them.ResultsThe valgus moved by 1.3 ± 1.3° beyond 90° knee flexion during passive flexion. In contrast, during cross-legged flexion, the varus moved by 4.6 ± 5.1° beyond 30° flexion. This indicated significantly increased varus alignment in the cross-legged flexion as compared with passive flexion. Beyond 60° of flexion, the femur displayed 8.8 ± 4.8° of external rotation relative to the tibia. In cross-legged flexion, the femur displayed 9.2 ± 6.5° of external rotation relative to the tibia beyond 45° of flexion. At 90° of flexion, the cross-legged knees rotated more externally. There were no significant postoperative differences between the high- and low-score clusters.ConclusionThe intraoperative knee kinematics after BCS-TKA during high-flexion motions differed depending on the performance of an individual. This will be useful for physicians who might recommend BCS-TKA to new patients.     

Analgesia for total knee arthroplasty: a meta-analysis comparing local infiltration and femoral nerve block

Patients frequently experience postoperative pain after a total knee arthroplasty; such pain is always challenging to treat and may delay the patient''s recovery. It is unclear whether local infiltration or a femoral nerve block offers a better analgesic effect after total knee arthroplasty.We performed a systematic review and meta-analysis of randomized controlled trials to compare local infiltration with a femoral nerve block in patients who underwent a primary unilateral total knee arthroplasty. We searched Pubmed, EMBASE, and the Cochrane Library through December 2014. Two reviewers scanned abstracts and extracted data. The data collected included numeric rating scale values for pain at rest and pain upon movement and opioid consumption in the first 24 hours. Mean differences with 95% confidence intervals were calculated for each end point. A sensitivity analysis was conducted to evaluate potential sources of heterogeneity.While the numeric rating scale values for pain upon movement (MD-0.62; 95%CI: -1.13 to -0.12; p=0.02) in the first 24 hours differed significantly between the patients who received local infiltration and those who received a femoral nerve block, there were no differences in the numeric rating scale results for pain at rest (MD-0.42; 95%CI:-1.32 to 0.47; p=0.35) or opioid consumption (MD 2.92; 95%CI:-1.32 to 7.16; p=0.18) in the first 24 hours.Local infiltration and femoral nerve block showed no significant differences in pain intensity at rest or opioid consumption after total knee arthroplasty, but the femoral nerve block was associated with reduced pain upon movement.     

膝内翻患者全膝关节置换术后保留轻度内翻对临床效果的影响

目的 评价膝内翻患者全膝关节置换术后保留轻度内翻对临床效果的影响。方法 对2016年3月至2019年11月于武汉大学人民医院因膝内翻膝关节骨性关节炎行TKA治疗的93例（93膝）患者的临床资料进行回顾性分析。其中,男17例,女76例;年龄71 ～ 87岁,平均77岁。按患者术后下肢力线角度将患者分为中立组、轻度内翻组、严重内翻组。用ROM、HSS、AKS评分量表评价患者膝关节功能。结果 患者随访时间15 ～ 47个月,平均（24.4±8.9）个月,ROM术前平均（49.9±6.7）°,术后末次随访中立组、轻度内翻组、严重内翻组分别为平均（111.4±5.3）°、（112.2±5.0）°、（103.1±2.7）°,HSS评分术前平均（52.4±3.0）分,术后末次随访中立组、轻度内翻组、严重内翻组分别为平均（84.2±3.0）分、（87.1±2.6）分、（81.6±1.9）分,AKS功能评分术前平均（49.8±2.8）分,术后末次随访中立组、轻度内翻组、严重内翻组分别为平均（73.2±5.3）分、（80.1±3.0）分、（72.6±1.5）分,AKS活动评分术前平均（60.5±3.7）分,术后末次随访中立组、轻度内翻组、严重内翻组分别为平均（86.0±2.6）分、（89.9±2.0）分、（80.6±2.9）分,三组术后HSS、AKS评分均较术前有所提高,差异有统计学意义。结论 从短期随访来看,膝内翻患者全膝关节置换术后保持3° ～ 6°的轻度内翻会带来更好的临床疗效,但目前还不能判断内翻对齐和翻修率之间是否存在关联。     

单髁置换术与全膝关节置换术在治疗膝内侧单间室骨性关节炎术后早期关节遗忘度中的比较

目的 比较膝关节单髁置换术（unicompartmental knee arthroplasty, UKA）与全膝人工关节置换术（total knee arthroplasty, TKA）治疗膝内侧单间室骨性关节炎的早期膝关节功能评分与关节遗忘度评分,评价并分析两类术式在早期关节遗忘度评分方面的差异。方法 回顾性分析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月期间行全膝关节置换术及膝关节单髁置换术患者共296例,根据不同手术方式进行分组,其中TKA组共144例,UKA组共152例。出院后对患者术后1、3、6、12、24个月进行门诊复查,进行关节遗忘度评分、膝关节功能HSS评分、目测类比评分（VAS评分）。结果 (1)296例患者获得24～37个月的随访,平均随访（30.41±6.93）个月;(2)术后24个月TKA组与UKA组的HSS评分与VAS评分均明显好于术前,组内比较差异具有统计学意义（P<0.05）;(3)两组患者术后24个月膝关节VAS评分的改善程度差异无统计学意义（P>0.05）,UKA组的HSS评分改善程度好于TKA组,且差异有统计学意...     

Relationships between the changes in flexion contracture and standing flexion angle of the knee and sagittal spinal alignment after total knee arthroplasty

BackgroundThe sagittal spinal alignment interacts with the lower extremity in patients with combined degenerative disease of the spine and lower extremity. This study aimed to clarify the relationships between the reciprocal changes in sagittal alignment of the knee, pelvis, and spine after total knee arthroplasty (TKA) in osteoarthritis patients.MethodsProspectively, 36 patients who underwent primary TKA for severe knee osteoarthritis were enrolled. Their clinical and radiological evaluation included assessments of the knee flexion contracture (KFC) and standing knee flexion angle (KFA), as well as spinopelvic parameters and the global sagittal spinal alignment from standing whole-lower-extremity and whole-spine radiographs preoperatively and at postoperative 2 weeks, 6 weeks, 6 months, 1 year, and 2 years. Linear mixed models were used to assess the relationships between KFC/KFA and between spinopelvic/global sagittal spinal alignments.ResultsThe KFC decreased abruptly immediately after TKA, and the correction was maintained for 2 years postoperatively. The KFA decreased gradually and approached the value of the KFC after 2 years. Of the spinopelvic parameters, sacral slope and pelvic incidence decreased significantly, in ways related to changes in KFA. There was no significant relationship between sagittal spinal alignment and postoperative changes in KFC.ConclusionAlthough the flexion contracture was corrected immediately after TKA, the standing KFA improved gradually over 2 years. The pelvic parameters showed compensatory changes according to the KFA. The decompensated sagittal spinal malalignment was not related to a relapse in flexion contracture.