In vivo weight-bearing kinematics with medial rotation knee arthroplasty

Knee arthroplasties are designed to accommodate flexion, axial rotation and anteroposterior (AP) translation. Axial rotation during extension varies, with some rotating platform devices allowing unrestricted rotation while some conforming fixed-bearing designs almost none. The purpose of this study was to examine in vivo kinematics of a fixed-bearing medial rotation-type arthroplasty (MRK) during weight-bearing activities. Fifteen knees with a medial pivot TKA design were studied during step and pivot activities using lateral fluoroscopy and model-image registration. Average knee kinematics during the step activity showed little AP translation or rotation from 0°–100° flexion. During the pivot activity, the mean tibial internal rotation in individual knees was 7° (3°–19°). Mean condylar translations for individual knees were 3 mm medially and 5 mm laterally. The medial pivot prosthesis design provides anteroposterior stability during demanding activities, and exhibits a medial pivot motion pattern when subjected to twisting.     

Short-term functional advantages after medial unicompartmental versus total knee arthroplasty

Background

There are many uncertainties about the advantages and disadvantages of using unicompartmental (UKA) versus total knee arthroplasty (TKA) to treat patients with knee osteoarthritis. It is important to have sufficient early postoperative quadriceps strength for long-term, self-reported and gait-related outcomes after knee arthroplasty, but very limited comparative data exist regarding UKA and TKA patients.

Optimized functional femoral rotation in navigated total knee arthroplasty considering ligament tension

Femoral malrotation in total knee arthroplasty is correlated to an increased number of revisions. Anatomic landmarks such as Whiteside line, posterior condyle axis and transepicondylar axis are used for determining femoral component rotation. The femoral rotation achieved with the anatomical landmarks is compared to the femoral rotation achieved by a navigated ligament tension-based tibia-first technique.Ninety-three consecutive patients with gonarthritis were prospectively enrolled. Intraoperatively the anatomical landmarks for femoral rotation and the achieved femoral rotation using a navigated tension-based tibia-first technique were determined and stored for further comparison. A pre- and postoperative functional diagram displaying the extension and flexion and varus or valgus positions was also part of the evaluation.Using anatomical landmarks the rotational errors ranged from 12.2° of internal rotation to 15.5° of external rotation from parallel to the tibial resection surface at 90° flexion. A statistical significant improved femoral rotation was achieved using the ligament tension-based method with a rotational error ranged from 3.0° of internal rotation to 2.4° of external rotation. The functional analyses demonstrated statistical significant lower varus/valgus deviations within the flexion range and an improved maximum varus deviation at 90° flexion using the ligament tension-based method.Compared to the anatomical landmarks a balanced, almost parallel flexion gap was achieved using a navigation technique taking the ligament tension of the knee joint into account. As a result the improved femoral rotation was demonstrated by the functional evaluation. Unilateral overloading of the polyethylene inlay and unilateral instability can thus be avoided.     

Lateral subvastus lateralis versus medial parapatellar approach for total knee arthroplasty: A cadaveric biomechanical study

BackgroundThe standard of care for total knee arthroplasty (TKA) is a medial parapatellar approach (MPA). We aimed to study a novel lateral subvastus lateralis approach (SLA), which offers the benefit of keeping the extensor mechanism and medial soft tissues intact. To ensure the approach could be used safely in vivo, a biomechanical study was performed to assess whether the joint kinematics would be preserved after performing a TKA.MethodsA biomechanical study was conducted using 14 fresh-frozen cadaveric knees, with seven specimens each for the MPA and SLA. After a single radius, cemented cruciate retaining TKA was performed, specimens were tested on a VIVO joint motion simulator to measure and compare anterior/posterior, internal/external, and varus/valgus kinematics and laxity.ResultsThere was no significant difference in joint kinematics or laxity between the SLA and MPA groups.ConclusionBoth the SLA and MPA offer similar knee kinematics and laxity based on a cadaveric model. Although the surgical approach was different, inherently releasing different ligaments, both approaches resulted in a stable knee. This suggests that either approach will enable the surgeon to provide a stable knee, and that the implant itself may contribute a significant portion of the knee’s kinematics.     

Numbness after medial unicompartmental knee arthroplasty: Prevalence and effect on functional outcome

BackgroundThe prevalence of skin sensation alteration after total knee arthroplasty is well established but less so in medial unicompartmental knee arthroplasty (MUKA). The aim of this study was to determine the prevalence, extent of numbness and its effect on mid-term functional outcomes after MUKA.MethodsA level 2 prospective cohort study was conducted. Twenty patients (21 knees) were recruited. Demographics, length of surgical incision and the thigh-to-calf ratio was recorded. At the 1-year postoperative period, the extent of numbness was measured using a quantifiable grid-based system for both pinprick and fine touch. Preoperative, 3 months and 1 year postoperative Knee Society Scores (KSS) and 36-Item Short Form Health Survey (SF-36) scores were recorded.ResultsAt the 1-year postoperative period, the prevalence of numbness to both fine touch and pin prick was 58% and 66%, respectively. The mean area of numbness to fine touch and pin prick was 336 mm² and 521 mm²_, respectively. The prevalence and extent of numbness was not significantly associated with surgical factors such as incision length and thigh-to-calf ratio. Prevalence and extent of numbness was not significantly associated with SF-36 scores and KSS at the 1-year postoperative period.ConclusionsThere is a high prevalence of numbness around the knee 1 year after MUKA. Surgical incision length and thigh-to-calf ratio was not associated with the extent of numbness. The presence and extent of numbness did not affect functional outcomes scores at the 1-year postoperative period. This study finding allows for accurate preoperative counselling with regards to numbness and its effects for patients undergoing MUKA.     

三维有限元法分析膝关节内侧副韧带的生物力学功能

目的通过建立膝关节三维有限元模型,研究内侧副韧带维持膝关节稳定性的作用。方法膝关节韧带用金属丝标记,止点采用钻孔标记,行CT扫描,应用Mimics、Geomagic和Ansys软件对数据进行三维重建,建立膝关节三维有限元模型,在膝关节5个不同的屈曲角度下模拟膝关节的前后平移、外翻和内外旋运动。结果膝关节在屈曲0°、30°6、0°、90°和120°时,MCL的应力为4.84、3.55、2.17、1.26和0 MPa;膝关节在5个角度下向前平移时,MCL的应力为7.22、5.78、4.07、2.84和1.4 MPa;向后平移时,应力为8.14、6.454、.19、2.92和1.6 MPa;内旋时,应力为6.815、.233、.292、.25和0.97 MPa;外旋时,应力为6.285、.003、.342、.21和0.82 MPa;外翻时,应力为11.00、9.55、7.25、5.94和3.11 MPa。结论通过建立膝关节三维有限元模型模拟膝关节前后移、外翻和内外旋各动作,可以有效地分析膝关节内侧副韧带的生物力学功能。     

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.

Femoral component rotation in mobile-bearing total knee arthroplasty

The surgical technique utilized for the LCS mobile-bearing since 1977 has been a tibial cut first method which requires determination of femoral rotation with tension spacing. We evaluated 38 randomly selected mobile-bearing TKA in which this technique was utilized. All cases had satisfactory clinical results. Spiral computed tomography scans measured the posterior condylar angle which is the angle of the femoral component posterior condyles in relation to the surgical transepicondylar axis. The mean femoral component alignment was 0.3 degrees of internal rotation to the transepicondylar axis (S.D.=2.2 degrees ; range=6 degrees internal to 4 degrees external). Four cases (10%) were outside of 3 degrees from the TEA. Lateral patellar tilt and subluxation was identified in one female who had a femoral component position of 5 degrees internal rotation. In 90% of cases, the posterior condylar angle was within 3 degrees of the surgical transepicondylar axis which is regarded as the functional ideal for conventional methods.     

Revision of Oxford medial unicompartmental knee arthroplasty to total knee arthroplasty - results of a multicentre study

The advantages of Unicompartmental Knee Replacement (UKR) over Total Knee Replacement (TKR) includes the preservation of soft tissue as well as bone stock, and better function with improved range of motion and more natural gait. It is therefore believed that the revision of failed UKR to TKR is technically easier than revision of failed TKR. In our study we tested this hypothesis by assessing the reconstruction requirements and early clinical and radiological outcome following the revision of UKR to TKR. During a 15-year period 1060 primary Oxford medial UKR procedures were performed at three centres, 36 of which underwent revision to TKR due to aseptic failure. The mean operating time for revision surgery was 113 min. Among the revision prostheses used, 28 were standard TKRs, six were constrained, and two were semi-constrained. Thirty had no intramedullary stems whereas six had intramedullary stems. In 30 cases reconstruction for bone loss was not required whereas metal augmentation was used in two knees, contained peg defects in the femur were filled with cement in two knees and contained keel defects in the tibia were grafted using the bone from revision cuts in two knees. After a mean follow-up of 2 years, the mean 'total knee score' was 86.3 and the mean functional score was 78.5. These findings suggest that the complexity of operation and complications encountered during Oxford medial UKR revision and the clinical outcome compare favorably with those of TKR revision.     

具备内外旋自由度的双侧减压辅具对膝关节生物力学的影响

目的针对传统膝关节辅具对人体下肢运动自由度限制的问题,为辅具提供一种顺应膝关节内外旋自由度的设计方案。方法通过在辅具中增加双自由度铰链的设计释放内外旋自由度,设置佩戴具备和不具备双自由度铰链的双侧减压辅具实验组、未佩戴辅具对照组进行步态及力学实验测试。结果步态过程中,相比不具备双自由度铰链的辅具,具备双自由度铰链的辅具对膝关节内外旋运动的限制较小,且辅具可以为人体膝关节提供一定牵引力。结论顺应内外旋自由度的设计方案可以有效减少双侧减压辅具对膝关节运动的限制。     

活动与固定平台单髁置换治疗膝关节内侧单间室骨关节炎的随访

文题释义：单髁假体置换：为人工膝关节置换的一个特殊类型,是一种置换范围局限在单侧髁的置换。膝单髁关节置换与全膝关节置换几乎同时起步于20世纪70年代初期,单髁关节置换的目的是尽可能地保留正常的关节结构,以期获得更好的功能恢复,目前临床上单髁假体有活动平台和固定平台两种单髁假体。下肢机械轴位置Kennedy和White分布：把胫骨平台分为0、1、2、C、3、4、5几个区域,观察股骨头中心—踝关节中心连线经过胫骨平台的区域。KENNEDY和WHITE的研究发现,单髁置换后下肢机械轴经过2、C区的术后效果好,并发症少。背景：单髁置换假体主要分为活动平台和固定平台2种类型,由于两种平台假体的设计理念和手术操作方法上的不同,对于两种平台假体的选择还有一定分歧和争议。 目的：比较活动与固定平台单髁假体置换治疗膝关节内侧间室骨性关节炎的临床效果。 方法：选择2014年2月至2015年2月佛山市中医院收治的单侧膝关节内侧间室骨关节炎患者154例,男54例,女100例,年龄56-81岁,其中100例接受活动平台单髁假体置换治疗(活动平台组),54例接受固定平台单髁假体置换治疗(固定平台组)。记录并发症发生情况。术后随访膝关节目测类比评分、膝关节活动度、膝关节功能与临床KSS评分,复查X射线片(胫股角、髋-膝-踝角度、胫骨后倾角)评估下肢力线矫正情况。研究符合佛山市中医院对研究的相关伦理要求(fsz20130642)。结果与结论：①154例患者术后获得60-72个月的随访;②两组末次随访的膝关节目测类比评分、膝关节活动度、膝关节功能与临床KSS评分均较术前明显改善(P < 0.05),两组间比较差异无显著性意义(P > 0.05);③两组末次随访的胫股角、髋-膝-踝角度、胫骨后倾角均较术前明显改善(P < 0.05),活动平台组胫股角与髋-膝-踝角度的矫正值大于固定平台组(P < 0.05),两组间胫骨后倾角矫正值比较差异无显著性意义(P > 0.05);两组间下肢机械轴位置Kennedy和White分布比较差异无显著性意义(P > 0.05);④活动平台组出现1例假体松动,2例衬垫脱位;⑤结果表明,两种平台单髁置换假体治疗膝关节内侧间室骨性关节炎的中期随访临床结果无明显差异,但活动平台单髁假体置换下肢力线矫正角度较固定平台大,对于恢复下肢解剖轴线更有优势;2种单髁假体术后并发症发生率均较低,活动平台单髁置换后中期随访并发症发生率高于固定平台,活动平台中期并发症主要是假体松动、衬垫脱位。ORCID: 0000-0001-9062-8026(刘少华) 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     

Gait and functional status analysis before and after total knee arthroplasty

Background

Among the procedures for severe gonarthrosis, total knee arthroplasty (TKA) is considered a successful method patient satisfaction and functional improvement; however, TKA is commonly associated with incompletely recovered gait function. The aim of this study was to evaluate the influence of TKA and physiotherapy programmes on gait features and patient-reported functional status and the relationship between them, leading to broader knowledge of the origins of long-term gait disturbances.

从生物力学角度评价单髁置换术与腓骨截骨术

膝关节单间室骨性关节炎引起的膝内翻是常见病症之一,目前手术方法主要有胫骨高位截骨术、单髁置换术以及最新推广的腓骨截骨术。单髁置换术自开展以来已有60余年历史,相比全膝关节置换术具有可保留膝关节正常运动、手术创伤小、保留骨量多以及术后关节活动度大等优点,故单髁置换术已成为治疗内侧间室骨关节炎一种可靠的治疗方式。腓骨截骨术是一种治疗膝内翻的新治疗手段,具有手术简单、费用低、恢复快等优点,目前正在被大力推广,但其治病机制尚不很清楚。综述单髁置换和腓骨截骨两种临床手术方式,并从生物力学角度推论腓骨截骨术治疗内侧间室骨性关节炎的可能机制,提出腓骨截骨术后外侧收缩肌力下降导致关节合力矩再平衡,故关节接触位置改变、关节接触力下降可能是腓骨截骨术能够缓解疼痛治疗骨性关节炎的原因。     

从生物力学角度评价单髁置换术与腓骨截骨术

膝关节单间室骨性关节炎引起的膝内翻是常见病症之一,目前手术方法主要有胫骨高位截骨术、单髁置换术以及最新推广的腓骨截骨术。单髁置换术自开展以来已有60余年历史,相比全膝关节置换术具有可保留膝关节正常运动、手术创伤小、保留骨量多以及术后关节活动度大等优点,故单髁置换术已成为治疗内侧间室骨关节炎一种可靠的治疗方式。腓骨截骨术是一种治疗膝内翻的新治疗手段,具有手术简单、费用低、恢复快等优点,目前正在被大力推广,但其治病机制尚不很清楚。综述单髁置换和腓骨截骨两种临床手术方式,并从生物力学角度推论腓骨截骨术治疗内侧间室骨性关节炎的可能机制,提出腓骨截骨术后外侧收缩肌力下降导致关节合力矩再平衡,故关节接触位置改变、关节接触力下降可能是腓骨截骨术能够缓解疼痛治疗骨性关节炎的原因。     

从生物力学角度评价单髁置换术与腓骨截骨术

膝关节单间室骨性关节炎引起的膝内翻是常见病症之一，目前手术方法主要有胫骨高位截骨术、单髁置换术以及最新推广的腓骨截骨术。单髁置换术自开展以来已有60余年历史，相比全膝关节置换术具有可保留膝关节正常运动、手术创伤小、保留骨量多以及术后关节活动度大等优点，故单髁置换术已成为治疗内侧间室骨关节炎一种可靠的治疗方式。腓骨截骨术是一种治疗膝内翻的新治疗手段，具有手术简单、费用低、恢复快等优点，目前正在被大力推广，但其治病机制尚不很清楚。综述单髁置换和腓骨截骨两种临床手术方式，并从生物力学角度推论腓骨截骨术治疗内侧间室骨性关节炎的可能机制，提出腓骨截骨术后外侧收缩肌力下降导致关节合力矩再平衡，故关节接触位置改变、关节接触力下降可能是腓骨截骨术能够缓解疼痛治疗骨性关节炎的原因。     

人工单髁关节置换治疗膝内侧间室骨性关节炎临床疗效分析

目的 探讨人工单髁关节置换(UKA)在膝内侧间室骨性关节炎治疗中的适应证选择、临床疗效及假体生存率。方法 回顾性分析2007年4月至2017年4月应用UKA治疗膝内侧间室骨性关节炎共500例患者的随访结果。其中,男176例,女324例;年龄43～91岁,平均61.12岁。根据年龄分组:中龄组133例,老龄组295例,高龄组72例。根据Iwano髌股关节影像学分级分组:0-1级组104例,2级组179例,3级组182例,4级组35例。通过膝关节活动度(ROM)、KSS评分与OKS评分评估临床疗效,记录术后并发症的发生率。采用Kaplan-Meier生存分析对单髁关节假体生存率、不同年龄与髌股关节退变程度对假体生存率的影响进行评估。结果500例患者均获得随访,末次随访时间2018年11月,共随访1.59～11.60年,平均5.27年。膝关节ROM:术前111°,术后117°(=-2.334,0.05); KSS评分:术前59分,术后93分(=-2.586,0.05); OKS评分:术前24分,术后45分(=-2.056,0.05)500例患者中共有20例术后并发症发生,人工单髁关节10年假体生存率为96.0%。年龄分组:中龄组10年假体生存率为89.8%,老龄组为99.0%,高龄组为97.2%,三组整体比较,差异有统计学意义(=12.37,=0.02);对于术后KSS及OKS评分而言,不同年龄组在整体比较以及组间比较并无明显差异,但老龄组术后膝关节活动度ROM显著高于高龄组患者,差异有统计学意义(=0.042)。Iwano影像学分级分组:0-1级组假体生存率为98.9%,2级组为92.7%,3级组为97.8%,4级组为96%,差异无统计学意义(=4.162,=0.244); Iwano各期患者术后ROM及KSS评分均未发现显著不同,4级组对术后OKS评分有显著降低,差异有统计学意义(=10.627,=0.00)。结论 UKA治疗膝内侧间室骨关节炎能够取得良好的临床疗效,传统单髁置换手术适应证可能已不再适应现代单髁置换手术,可通过准确的适应证选择以及精确的手术操作,以保证UKA获得良好效果,降低并发症发生率。     

Sporting and physical activity following Oxford medial unicompartmental knee arthroplasty

The purpose of this study was to evaluate and assess the sporting and physical activities of patients who had undergone an Oxford medial unicompartmental knee arthroplasty (UKA). Seventy-six patients who underwent a UKA between 2000 and 2003 were reviewed. Demographic data such as age, sex and comorbidities were recorded. University of California Los Angeles (UCLA) activity level ratings and Oxford knee scores were determined for each patient. The sporting and physical activities of all patients' pre- and post-operatively were recorded. The mean age of patients was 64 years (range 49-81) at surgery and 66 years (range 53-82) at review. The mean follow up time was 18 months (range 4-46). Following surgery there was a significant improvement in UCLA activity level scores from 4.2 to 6.5 (Wilcoxon Matched-pairs Signed-rank Test, p<0.01). Forty-two patients (64%) regularly participated in sport before they became symptomatic with significant knee pain, and thirty-nine patients (59%) regularly participated in sports after surgery. In total 93% of patients successfully returned to their regular sporting and physical activities following surgery. The published long-term survivorship of the Oxford UKA has given surgeons increasing confidence to use the prosthesis on a younger generation of patients. Our study has demonstrated that this population of patients is extremely active. A more detailed study is required to evaluate the long-term effects of sporting activity on the Oxford UKA.     

Patient satisfaction after posterior-stabilized total knee arthroplasty: A functional specific analysis

BackgroundDespite the success of total knee arthroplasty (TKA) in treating end-stage knee arthritis, 11% to 19% of patients are dissatisfied with the outcome of their surgery. In this study we investigated how satisfied overall patients are with the outcome of posterior stabilized TKA and what particular functional deficits or residual symptoms cause the most dissatisfaction for patients after surgery.MethodsUsing patient-completed validated questionnaires, we retrospectively analyzed data for 1013 posterior-stabilized TKAs performed in 748 Chinese patients regarding the overall satisfaction with surgery and the importance ranking of each of 15 specific functions and residual symptoms.ResultsOur data demonstrate an overall satisfaction rate of 87.4%. Satisfaction percentages ranged from 45.0% to 89.0%. The top 6 dissatisfactory items were sitting with legs crossed (dissatisfaction rate of 55.0%), squatting (51.7%), walking fast or jogging (45.4%), knee clunking (34.5%), abnormal feeling in knee (31.2%), and climbing stairs (28.2%). The top 6 important functions or issues were pain relief, walking on flat ground, climbing stairs, ability to return to household work, decreased limping, and squatting.ConclusionsApproximately 1 in 8 patients was dissatisfied with overall outcome. Patients were most dissatisfied with climbing stairs and squatting, functions that they considered most important.     

Mid-term functional,clinical, and radiological outcomes with factors affecting revision of mobile-bearing medial unicompartmental knee arthroplasty

BackgroundTo evaluate and compare the clinical and radiological outcomes of patients subjected to medial unicompartmental knee arthroplasty (UKA).MethodsThe study included 146 knees of 115 consecutive medial UKAs patients with a minimum five-year follow-up. Pre- and postoperative functional and clinical outcomes were measured using the Visual Analog Scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), American Knee Society Score (AKSS-O), knee range of motion (ROM), and Short-Form Health Survey (SF-36). The Kellgren–Lawrence osteoarthritis (OA) grading system was used for the evaluation of the OA status. The joint line convergence angle (JLCA) of the operated and contralateral knee, the tibiofemoral coronal angle (TFCA), and the tibial slope angle were used in the radiological evaluation.ResultsThe mean age of patients was 58.8 ± 7.0 years. The mean follow-up period was 7.41 ± 1.54 years. Good to excellent functional outcomes were obtained according to VAS, WOMAC, OKS, AKSS-O, and SF-36 scores. Insert dislocation was the main reason for revision surgery (nine patients, 90%). Preoperative body mass index (BMI), postoperative BMI, American Society of Anesthesiologists (ASA) Score, postoperative knee flexion contracture, mean increase in postoperative medial joint space (PMJS) height, and OA progression were found to affect the revision status.ConclusionsGood to excellent functional, clinical, and radiological outcomes were obtained with medial UKA at a minimum follow-up of five years. Differences in preoperative and postoperative radiological parameters except an increase in PMJS height had no impact on revision status.     

Unicompartmental knee arthroplasty for spontaneous osteonecrosis of the medial tibial plateau

Background

There have been very few reports on isolated medial tibial plateau osteonecrosis, and the condition has not been clearly described. Unicompartmental knee arthroplasty (UKA) may be an appropriate treatment method for this condition. The aims of this study were to report our experience of using mobile-bearing knee implants for osteonecrosis of the medial tibial plateau and to discuss the etiology and treatment of this type of osteonecrosis.