Comparison of Modular Conventional and High-Flexion Posterior-Stabilized Total Knee Arthroplasties in the Same Patients at a Mean Follow-Up of 15 Years

BackgroundAs previous studies are limited to short-term clinical data on conventional and high-flexion total knee arthroplasties (TKAs), long-term clinical data on these TKAs remain unclear. Therefore, we evaluated long-term functional outcome, range of knee motion, revision rate, implant survival, and the prevalence of osteolysis after conventional and high-flexion TKAs in the same patients.MethodsThe authors evaluated a cohort of 1206 patients with a mean age of 65.3 ± 7 years (range: 22-70) who underwent bilateral simultaneous sequential TKAs. One knee received a conventional TKA and the other received a high-flexion TKA. The mean duration of follow-up was 15.6 years (range: 14-17).ResultsNo significant differences were found between the 2 groups at the latest follow-up with respect to Knee Society score (93 vs 92 points, P = .765), pain score (45 vs 44 points, P = .641), range of knee motion (125° vs 126°, P = .712), and radiographic and computed tomography scan results. Furthermore, no significant revision rate differences were found between the 2 groups (1.3% for conventional TKA vs 1.6% for high-flexion TKA; P = .137). There was no osteolysis recorded in either group. The rate of survivorship free of implant revision or aseptic loosening was 98.7% (95% CI = 91-100) for conventional TKA and 98.4% (95% CI = 91-100) for high-flexion TKA at 17 years.ConclusionAt the latest follow-up, we were not able to demonstrate any significant difference between conventional and high-flexion TKAs with respect to functional outcome scores, range of knee motion, revision rate, implant survival, and prevalence of osteolysis.     

Is Range of Motion After Cruciate-Retaining Total Knee Arthroplasty Influenced by Prosthesis Design? A Prospective Randomized Trial

Improvement in knee flexion is a major expectation for many patients undergoing total knee arthroplasty (TKA). One hundred and twenty two patients were randomized to receive a cruciate-retaining standard or high-flexion TKA. Range of motion (ROM) and functional outcomes were assessed. The high flexion implants had a greater intraoperative ROM than standard implants. The mean flexion preoperatively, intraoperatively and at the one year follow-up was 107.4°, 123.0° and 108.9° in the standard group and 109.9°, 129.1° and 109.7° in the high-flexion TKA group. These differences were not significant preoperatively and at follow-up, but intraoperatively (P < 0.001). In multivariate analysis preoperative knee flexion was the only significant factor influencing knee flexion at follow-up. No differences in the Knee Society Score or SF 36 were observed.     

Comparison of In Vivo Patellofemoral Kinematics for Subjects Having High-Flexion Total Knee Arthroplasty Implant With Patients Having Normal Knees

This study compares the in vivo patellar kinematics of high-flexion posterior cruciate ligament-retaining and posterior-stabilized total knee arthroplasty (TKA) implants with that of the healthy knee. Twenty-seven subjects performing weight-bearing deep knee bends were analyzed under fluoroscopic surveillance from full extension to maximum flexion. The patellofemoral contact positions and patellar flexion were similar for both TKAs. At low flexion, the patellofemoral contact was significantly more distal on the healthy patella than on the TKA patella, but in deeper flexion, there was no difference among the 3 groups. The tibiopatellar angle was similar for all 3 groups, except at deep flexion where the healthy patella rotated significantly more than the implanted ones. Patellofemoral separation was observed in some TKA knees, whereas it was absent in the healthy knees.     

Knee kinematics of high-flexion activities of daily living performed by male Muslims in the Middle East

Full flexion is critical for total knee arthroplasty (TKA) patients in the Middle East, where daily activities require a high range of motion in the lower limb. This study aimed to increase understanding of the knee kinematics of normal Muslim subjects during high-flexion activities of daily living, such as kneeling, Muslim prayer, sitting cross-legged, and squatting. The early postoperative kinematics for a select group of Muslim, high-flexion TKA patients are also reported. Mean curves were compared between the normal group and the TKA group. During kneeling, the average maximum flexion was 141.6° for the normal group and 140.2° for the TKA group. The normal group's maximum and minimum knee angles (flexion, abduction, external rotation) were reported and, with the exception of maximum extension, were not significantly different from the TKA group, despite short postoperative times.     

In Vivo Kinematic Analysis of a High-Flexion, Posterior-Stabilized, Mobile-Bearing Knee Prosthesis in Deep Knee Bending Motion

The objective of this study was to evaluate the kinematics of a high-flexion, posterior-stabilized, mobile-bearing total knee arthroplasty (TKA) in weight-bearing, deep knee bending motion. Thirteen patients implanted with the Legacy Posterior Stabilized Flex (Zimmer, Warsaw, IN) mobile-bearing TKA were examined during a deep knee bending motion using fluoroscopy. Femorotibial motion was determined using a 2-dimensional to 3-dimensional registration technique, which used computer-assisted design models to reproduce the position of metallic implants from single-view fluoroscopic images. The average flexion range of motion between the metallic implants was 116°. The average rotation of the femoral component was 9.3° external rotation. The mean kinematic pathway was early rollback, lateral pivot with external rotation, and bicondylar rollback. We found that the kinematic pattern of the Legacy Posterior Stabilized Flex mobile-bearing TKA was different than normal knee kinematics.     

Effect of adjunctive range-of-motion therapy after primary total knee arthroplasty on the use of health services after hospital discharge.

INTRODUCTION: There is controversy as to whether continuous passive motion (CPM) after total knee arthroplasty (TKA), which is the standard treatment, confers significant benefit with respect to outcome. The primary purpose of this study was to determine if CPM or slider-board (SB) therapy, used as adjuncts to standardized exercises (SEs) during the acute-care hospital stay, resulted in a reduced total length of hospitalization and post-discharge rehabilitation in patients who underwent primary TKA. METHODS: We carried out a randomized, clinical trial on 120 patients who received a TKA at the University of Alberta Hospital, Edmonton, a tertiary care institution. The study horizon began at the point of discharge from the hospital and continued up to 6 months after operation. Postoperatively, patients (40 in each group) received CPM and SEs, SB therapy and SEs or SEs alone while in the tertiary Health service use was compared using transfer institution length of stay(LOS), post-discharge rehabilitation, readmission and complication rates and their associated costs. RESULTS: There were no differences in health service use or costs among the 3 groups over the 6-month study. The rates of postoperative complications and readmissions also were similar among the groups. Increased health service use associated with knee flexion that was less than 60 degrees at discharge, but similar proportions of patients with poor knee range of movement (ROM) at discharge were found in each group. CONCLUSIONS: This finding suggests that adjunctive ROM therapy, as used in this study, does not reduce health service use. Further research is required to determine if adjunctive ROM therapy after discharge from the surgical hospital decreases health service utilization in those patients who have poor knee ROM at the time of discharge.     

Range of motion and function are similar in patients undergoing TKA with posterior stabilised and high-flexion inserts

It is debatable whether high-flexion (HF) total knee arthroplasty (TKA) designs will improve postoperative flexion and function or will diminish the need for manipulation under anaesthesia (MUA). We retrospectively analysed range of motion (ROM), flexion, Knee Society Score (KSS), and rate of MUA in a consecutive group of patients who underwent TKA with a conventional posterior stabilised (PS) insert or an HF insert using identical surgical technique, implant design, and postoperative care. Fifty TKAs with a standard PS insert were matched for patient’s age, gender, preoperative ROM, and KSS with 50 TKA performed with an HF insert. The patient’s ROM and KSS were evaluated at six weeks, four months, and one year postoperatively. The outcome variables (flexion, ROM, KSS, and manipulation rate) in both groups were compared using the generalised estimating equations method. A second analysis of patients with preoperative flexion ≥120° was performed. The ROM, flexion, and patient-reported KSS was similar in both groups at each time period. The rate of MUA was also similar. Patients with a preoperative ROM of at least 120° showed similar results. Our study found that one year after surgery, patients who underwent TKA with a PS or an HF insert achieved similar flexion, ROM, and function.     

20-Year Minimum Outcomes and Survival Rate of High-Flexion Versus Standard Total Knee Arthroplasty

BackgroundThere are conflicting reports of early and mid-term results of the high-flexion total knee arthroplasties (TKAs). The purpose of the present long-term follow-up study was to determine the long-term (minimum 20 years) clinical and radiographic and CT scan results, and the survival rates of high-flexion versus standard TKAs.MethodsNinety-five patients (190 knees) were included (mean age, 65 ± 6.5 years). The mean follow-up was 20.3 years (range, 20 to 20.6 years).ResultsRevision of the TKA was performed in 5 knees (5.2%) with high-flexion TKA and in 3 knees (3.2%) with standard TKA. The rate of survival at 20 years was 94.8% (95% CI, 91%-98%) in the high-flexion TKA group and 96.8% (95% CI, 92%-100%) in the standard TKA group with reoperation for any reason. No knee had osteolysis in either group.ConclusionsAt this length of follow-up, high-flexion TKA has comparable outcomes and survivorship to standard TKA.     

高屈曲假体初次全膝关节置换术早期随访结果的Meta分析

目的 分析有关高屈曲假体与普通假体初次全膝关节置换术后疗效比较的文献,对术后关节活动度(range of motion,ROM)及膝关节功能评分(HSS、KSS、WOMAC)进行Meta分析.方法 检索Medline(1966年1月至2009年10月),Embase(1966年1月至2009年10月),维普资讯(1989年1月至2009年10月)和CNKI(1979年1月至2009年10月)等数据库中关于高屈曲假体与普通假体在初次伞膝关节置换术中应用的疗效比较的前瞻性随机对照研究,纳人符合标准的文献,提取相关数据输入Review Manager 4.2软件进行统计学分析.术后ROM和膝关节功能评分均采取权重均差(weighted mean difference,WMD)进行评价.结果 共6篇文献符合纳入标准,经改良Jadad评分均判定为高质量研究.纳入病例466例,高屈曲假体组和普通假体组术后ROM合并WMD为1.64195%C1(-0.04,3.32),P=0.06],膝关节HSS评分合并WMD为0.34[95%CI(-1.12,1.79),P=0.65],膝关节KSS评分合并WMD为-0.67[95%CI(-2.22,0.89),P=0.40],膝关节WOMAC评分合并WMD为1.66195%C1(-4.03,7.35),P=0.57].高屈曲假体组与普通假体组的ROM、HSS、KSS、WOMAC的差异无统计学意义.结论 初次全膝关节置换术后高屈曲假体组相比普通假体组ROM无明显改善,膝关节功能评分无明显差异.     

Conversion Total Knee Arthroplasty Needs Its Own Diagnosis-Related Group Code

BackgroundConversion from a prior knee procedure has been demonstrated to require greater operative times and resources, but still lacks a separate procedural or facility code from primary total knee arthroplasty (TKA). The purpose of this study is to determine differences in facility costs between patients who underwent primary TKA and those who underwent conversion TKA.MethodsWe retrospectively reviewed a consecutive series of patients undergoing primary TKA at 2 hospitals from 2015 to 2017, comparing itemized facility costs between primary and conversion TKA patients. A multivariate regression analysis was performed to identify independent risk factors for increased facility costs, the need for additional implants, length of stay, and discharge disposition.ResultsOf 2447 TKA procedures, 678 (27.7%) underwent conversion TKA, which was associated with greater implant costs ($3931.47 vs $2864.67, P = .0120) and total facility costs in a multivariate regression ($94.30 increase, P = .0316). When controlling for confounding variables, patients with a prior ligament reconstruction ($402 increase, P = .0002) and prior open reduction and internal fixation ($847 increase, P = .0020) had higher costs and were more likely to require stemmed implants (P < .05). There was an increase in TKA implant cost by $538 in patients with implants from a prior procedure (P < .0001).ConclusionConversion TKA is associated with greater implant and inpatient facility costs than primary TKA, particularly those who had a history of an open knee procedure. A separate diagnosis-related group should be created for conversion TKA given the increased cost and complexity of these procedures compared to primary TKA.     

Range of motion of standard and high-flexion cruciate retaining total knee prostheses

Recently, use of high-flexion design was introduced in cruciate-retaining (CR) total knee prostheses. The purpose of this study was to prospectively compare the ranges of motion (ROMs) of 89 knees with standard and 87 knees with high-flexion CR total knee prostheses. Differences in age, gender, diagnosis, preoperative ROM of the knee, and Knee Society Score between the 2 groups were not statistically significant. At 12-month follow-up, average ROM was 112.0 degrees +/- 12.6 degrees for standard, and 115.3 degrees +/- 13.4 degrees for high-flexion CR prosthesis (P = .101). To our knowledge, this is the first report on the ROM with the high-flexion CR total knee prosthesis. Using the technique of anterior referencing for femoral component sizing and using a fixed 7 degrees slope for the tibial component, we found no significant differences between groups with regard to ROM, clinical, or radiographic parameters.     

Good Postoperative Flexion Angle Improves Knee Function and Improvement of Flexion Angle Increases Patient Satisfaction After Total Knee Arthroplasty

BackgroundTotal knee arthroplasty (TKA) is a well-established procedure for treating knee joint diseases. However, the postoperative range of motion (ROM) varies and is an important indicator of TKA success. Recently, patient-reported outcome measures (PROMs) and patient satisfaction have drawn attention. However, the relationship between ROM and knee function obtained by PROM and satisfaction is not well understood.MethodsWe retrospectively reviewed the data of 375 patients who underwent 500 primary TKA procedures. We measured the ROM before and after surgery. Knee joint function was evaluated using the Knee Injury Osteoarthritis Outcome Score, a PROM, and patients were classified into good function and poor function groups. Patient satisfaction was evaluated on a 5-graded scale as overall satisfaction, and patients were divided into a satisfied or a dissatisfied group according to the obtained scores. ROM was compared between the 2 groups, then significantly different factors were analyzed using multiple logistic regression analysis. Moreover, cut-off points of ROM for obtaining good function and patient satisfaction were determined using ROC curve analysis.ResultsThe postoperative flexion angle had a significant effect on knee function (P < .001). The cut-off value of the postoperative flexion angle for good knee function was 120°. The improvement in flexion angle had a significant effect on patient satisfaction (P = .004). The cut-off value for the improvement in the flexion angle was 5°.ConclusionThe postoperative flexion angle had a significant effect on knee function and improvement in the flexion angle had a significant effect on patient satisfaction.     

All-polyethylene and metal-backed tibial components in total knee arthroplasty: a matched pair analysis of functional outcome

A group of 98 patients who had primary unilateral total knee arthroplasty (TKA) with cemented, posterior-stabilized knee implants for osteoarthritis were matched for age, diagnosis, weight, body mass index, and presence of comorbid conditions. The patients were followed up with clinical, radiographic, and outcome measures including SF-36 scales and patient outcome questionnaires. Forty-nine patients had all-polyethylene tibial implants (APT), and 49 patents had metal backed tibial implants (MBT) with similar knee implant design and articular geometry. There is no difference among these patient cohorts in the clinical performance or functional outcome of TKA using APT or MBT components in primary TKA at intermediate term follow-up. In consideration of concerns about polyethylene wear, osteolysis, and cost associated with MBT components, these findings may present an opportunity for quality improvement and cost savings with increased utilization of APT in TKA operations.     

A Comparison Between Unstemmed and Stemmed Constrained Condylar Knee Prostheses in Primary Total Knee Arthroplasty: A Propensity Score‐Matched Analysis

ObjectiveTo compare and analyze the clinical outcomes between unstemmed and stemmed constrained condylar knees (CCK) in complex primary total knee arthroplasty (TKA) in terms of implant survivorship, change in outcome evaluations, and complications.MethodsWe reviewed 156 consecutive patients who received primary TKA using PFC®SIGMA®TC3 (TC3) of constrained condylar design between January 2009 and January 2017 at our institution. After removing patients who met exclusion criteria, 25 patients were identified as unstemmed TC3 cases and 81 as stemmed TC3 cases. Propensity score matching was used to select 25 stemmed cases as a control group for the unstemmed group with comparable preoperative conditions including preoperative demographics, preoperative diagnosis, preoperative range of motion, main reason to use TC3, ASA score (American Society of Anesthesiologists), and follow‐up duration. Preoperative and postoperative clinical evaluations including Knee Society Score (KSS), Hospital for Special Surgery (HSS) score, the 12‐Item Short‐Form Health Survey (SF‐12), and the range of motion (ROM) were obtained and compared. The instability, periprosthetic fracture, radiolucent lines, polyethylene wear, and heterotrophic ossification were assessed according to the anteroposterior and lateral radiographs of the knee. The complications and implant survivorship between the two groups were also recorded and compared.Results3After the index surgery, both groups showed substantial improvement in KSS (knee and function), HSS score, SF‐12, and ROM compared with baseline. There was no significant difference in the mean KSS scores (knee and function), HSS score, SF‐12, and ROM between the unstemmed and stemmed group postoperatively. No statistically significant difference was found in the overall complication rate between the two groups. The overall Kaplan–Meier survivorship was 98.0% (95% confidence interval 94.1%–100.0%) at 7 years. No significant difference was found in the survival rate between the unstemmed group (100.0%) and the stemmed group (96.0%) at 7 years (log rank, P = 0.317). The mean duration of follow‐up was 7.0 years for unstemmed group and 7.7 years for stemmed group.ConclusionsIn patients with adequate bone stock receiving complex primary TKA, unstemmed CCK could achieve similar clinical outcomes at mid‐term follow‐up as stemmed CCK.     

The Long-Term Results of Simultaneous High-Flexion Mobile-Bearing and Fixed-Bearing Total Knee Arthroplasties Performed in the Same Patients

Background

Our study determined the long-term clinical, radiographic, and computed tomography scanning results of high-flexion mobile-bearing and fixed-bearing total knee arthroplasties (TKAs) in the same younger patients. In addition, the survivorship and complication rates of both groups were evaluated.

TC-Dynamic后稳定型人工全膝关节系统术后近期疗效分析

目的探讨应用TC-Dynamic后稳定型人工全膝关节系统行全膝关节置换术(totalknee arthroplasty,TKA)的近期临床效果,评价其临床应用的可行性、安全性和有效性。方法2003年9月～2004年3月,应用TC-Dynamic人工全膝关节系统行TKA10例12膝(TC-Dynamic组),术前膝关节KSS(kneesocietyscore)评分为16.08±11.58分,功能评分为13.75±19.79分,膝关节活动度(rangeofmotion,ROM)为75.00±26.46°。同期使用Scorpio假体行TKA30例50膝(Scorpio组),术前膝关节KSS评分为19.48±9.67分,功能评分为3.16±19.82分,膝关节ROM为80.80±22.82°。比较两组患者术后疼痛缓解情况、KSS评分和功能评分改善情况,以及膝关节ROM的提高程度。结果所有患者术后获随访40～210d,平均130d。TC-Dynamic组术后KSS评分为88.83±4.04分,较术前改善72.75±14.47分,功能评分为79.17±5.15分,较术前改善65.42±19.47分;ROM为107.92±11.57°,较术前提高32.92±32.22°。Scorpio组术后KSS评分为85.68±7.36分,较术前改善66.20±10.44分,功能评分为71.40±12.70分,较术前改善68.24±25.35分;ROM为109.20±11.13°,较术前提高28.40±26.41°。术后各指标组间比较差异均无统计学意义(P>0.01)。两组患者术后X线片均示下肢力线良好,假体位置满意,无透亮线及任何松动迹象。结论TC-Dynamic后稳定型膝关节假体设计合理,术后近期效果良好;但远期疗效仍需大样本长期随访观察。TKA中正确的下肢力线、合理截骨和软组织平衡及屈曲伸直间隙平衡等,是获得良好临床效果和保证假体长期存活的关键。     

Clinical Outcomes After Simultaneous Bilateral Total Knee Arthroplasty : Comparison to Unilateral Total Knee Arthroplasty and Healthy Controls

The purpose of this study was to evaluate the functional outcomes of persons who underwent simultaneous bilateral total knee arthroplasty (TKA) compared to subjects who underwent unilateral TKA and a healthy control group. Fifteen subjects who underwent primary bilateral TKA and 15 sex, age, and body mass index-matched subjects who underwent primary unilateral TKA were observed prospectively for 2 years. Subjects in both surgical groups showed significant improvement in Knee Outcome Scores, Short Form 36 physical component scores, Timed Up and Go, and stair-climbing tasks (P ≤ .004). No differences in final outcomes were found between surgical groups. In addition, most 2-year clinical measures were no different between the surgical and control groups. Subjects medically appropriate for bilateral TKA should be afforded this option.     

Kinematic analysis of conventional and high-flexion cruciate-retaining total knee arthroplasties: an in vitro investigation

This study examined the kinematics of a cruciate-retaining (CR) total knee arthroplasty (TKA) component that attempts to enhance knee flexion by improving posterior tibiofemoral articular contact at high-flexion angles. Using an in vitro robotic experimental setup, medial and lateral femoral translations of this CR design were compared with that of a conventional CR TKA design and intact knee under a combined quadriceps and hamstring muscle load. Both CR TKA designs showed similar kinematics throughout the range of flexion (0 degrees -150 degrees ). The TKAs restored nearly 80% of the posterior femoral translation of the intact knee at 150 degrees . The posterior cruciate ligament (PCL) forces measured for the high-flexion CR TKA component indicate that the PCL is important in the mid-flexion range but has little effect on knee kinematics at high flexion.     

Long-Term Survival of Semi-Constrained Total Knee Arthroplasty for Revision Surgery

Semi-constrained implants provide stability in the setting of soft-tissue deficiency in revision total knee arthroplasty (TKA). This study evaluated our institution’s long-term survival results with a semi-constrained implant used in the revision TKA setting. 234 semi-constrained revision total knee arthroplasties were performed in 209 patients. The average follow-up was 9 years. Forty repeat revisions were performed. 5-year survival was 91% and 10-year survival was 81%. Male gender significantly increased the risk of revision. At 10 years the average range of motion, pain level, and Knee Society score improved significantly (P < 0.001). Ninety percent of patients reported an improvement in their knee. The semi-constrained implant used in revision knee arthroplasty has acceptable implant survival and functional outcomes in the long-term follow-up period.