Functional analysis of cemented medial unicompartmental knee arthroplasty

Gait analysis was used to study patients who underwent cemented medial unicompartmental knee arthroplasty (UKA) for medial compartment degenerative knee disease. All had excellent clinical function of the operated knee, with minimal involvement of other joints. Ten patients met the inclusion criteria for this study. Gait findings from this study group, as well as those from a similar cohort of patients who had undergone total knee arthroplasty (TKA), were compared with those for a group of normal patients. A greater percentage of patients (7 of 10) following UKA maintained the normal biphasic flexion/extension moment pattern about the knee or demonstrated a quadriceps overuse pattern, when compared with similar groups following TKA. In addition, the adduction moment in patients following UKA was significantly larger than in patients following TKA. The postoperative limb alignment correlated with the peak adduction moment recorded during the patient's gait analysis. The postoperative alignment may explain the differences in the adduction moment between the UKA and TKA patients, as there tended to be residual varus in the UKA population. The results of this study imply that preservation of the anterior cruciate ligament during UKA allows patients to maintain normal quadriceps mechanics, and that residual varus alignment subjects a medial UKA to higher loads.     

机器人辅助下单髁置换术的研究现状及进展

单髁置换术(UKA)对单间室骨关节炎患者来说是一种可选择的术式。与全膝关节置换术(TKA)比较,UKA的优势包括手术风险低、恢复快、患者满意度高、住院时间短等。然而,与TKA比较,UKA的翻修率更高,假体生存率更低。假如能提高传统UKA的假体生存率和降低其翻修率,UKA将会发挥独特的优势。目前,机器人辅助UKA正引起人...     

Navigated Unicompartmental Knee Arthroplasty: A Different Perspective

BackgroudAnteromedial osteoarthritis is a recognized indication for unicompartmental knee arthroplasty (UKA). Favorable postoperative outcomes largely depend on proper patient selection, correct implant positioning, and limb alignment. Computer navigation has a proven value over conventional systems in reducing mechanical errors in total knee arthroplasty (TKA). However, the lack of strong evidence impedes the universal use of computer navigation technology in UKA. Therefore, this study was proposed to investigate the accuracy of component positioning and limb alignment in computer navigated UKA and to observe the role of navigation in proper patient selection.MethodsA total of 50 knees (38 patients) underwent computer navigated UKA between 2016 and 2018. All operations were performed by the senior surgeon using the same navigation system and implant type. The navigation system was used as a tool to aid patient selection: knees with preoperative residual varus > 5° on valgus stress and hyperextension > 10° were switched to navigated TKA. We measured the accuracy of component placement in sagittal and coronal planes on postoperative radiographs. Functional outcomes were also evaluated at the final follow-up (a minimum of 16 months).ResultsNine patients had tibia vara and 14 patients had preoperative hyperextension deformity. We observed coronal outliers for the tibial component in 12% knees and for the femoral component in 10% knees. We also observed sagittal outliers for the tibial component in 14% knees and for the femoral component in 6% knees. There was a significant improvement in the functional score at the final follow-up. On multiple linear regression, no difference was found in functional scores of knees with or without tibia vara (p = 0.16) and with or without hyperextension (p = 0.25).ConclusionsOur study further validates the role of computer navigation in desirable implant positioning and limb alignment. We encourage use of computer-assisted navigation as a tool for patient selection, as it allows intraoperative dynamic goniometry and provides real-time kinematic behavior of the knee to obviate pitfalls such as significant residual varus angulation and hyperextension that predispose early failure of UKA.     

Knee stability before and after total and unicondylar knee replacement: in vivo kinematic evaluation utilizing navigation

Surgical navigation systems are currently used to guide the surgeon in the correct alignment of the implant. The aim of this study was to expand the use of navigation systems by proposing a surgical protocol for intraoperative kinematics evaluations during knee arthroplasty. The protocol was evaluated on 20 patients, half undergoing unicondylar knee arthroplasty (UKA) and half undergoing posterior-substituting, rotating-platform total knee arthroplasty (TKA). The protocol includes a simple acquisition procedure and an original elaboration methodology. Kinematic tests were performed before and after surgery and included varus/valgus stress at 0 and 30 degrees and passive range of motion. Both UKA and TKA improved varus/valgus stability in extension and preserved the total magnitude of screw-home motion during flexion. Moreover, compared to preoperative conditions, values assumed by tibial axial rotation during flexion in TKA knees were more similar to the rotating patterns of UKA knees. The analysis of the anteroposterior displacement of the knee compartments confirmed that the two prostheses did not produce medial pivoting, but achieved a postoperative normal behavior. These results demonstrated that proposed intraoperative kinematics evaluations by a navigation system provided new information on the functional outcome of the reconstruction useful to restore knee kinematics during surgery.     

The UniSpacer™: correcting varus malalignment in medial gonarthrosis

While options for operative treatment of leg axis varus malalignment in patients with medial gonarthrosis include several established procedures, such as unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA) or high tibial osteotomy (HTO), there has been little focus on a less invasive option introduced more recently: the UniSpacer™ implant, a self-centering, metallic interpositional device for the knee. This study evaluates clinical and radiological results of the UniSpacer™, whether alignment correction can be achieved by UniSpacer™ arthroplasty and alignment change in the first five postoperative years. Anteroposterior long leg stance radiographs of 20 legs were digitally analysed to assess alignment change: two relevant angles and the deviation of the mechanical axis of the leg were analysed before and after surgery. Additionally, the change of the postoperative alignment was determined one and five years postoperatively. Analysing the mechanical tibiofemoral angle, a significant leg axis correction was achieved, with a mean valgus change of 4.7 ± 1.9°; a varus change occurred in the first postoperative year, while there was no significant further change of alignment seen five years after surgery. The UniSpacer™ corrects malalignment in patients with medial gonarthrosis; however, a likely postoperative change in alignment due to implant adaptation to the joint must be considered before implantation. Our results show that good clinical and functional results can be achieved after UniSpacer™ arthroplasty. However, four of 19 knees had to be revised to a TKA or UKA due to persistent pain, which is an unacceptably high revision rate when looking at the alternative treatment options of medial osteoarthritis of the knee.     

Meta-analysis of navigation vs conventional total knee arthroplasty

Navigated total knee arthroplasty (TKA) is promoted as a means to improve limb and prosthesis alignment. This study involved a systematic review and meta-analysis for all randomized controlled trials in the literature from 1986 to 2009 comparing alignment outcomes between navigated and conventional TKA. Alignment outcomes were pooled using a random-effects model, and heterogeneity was explored. Twenty-three randomized controlled trials were identified comparing navigated vs conventional TKA involving 2541 patients. Patients who underwent navigated TKA had a significantly lower risk of implant malalignment at more than 3° as well as more than 2°. In addition, the risk of malalignment was reduced for the coronal plane tibial and femoral components as well as femoral and tibial slope. This meta-analysis demonstrates that navigated TKA provides significant improvement in prosthesis alignment.     

Unicompartmental knee arthroplasty for the treatment of unicompartmental osteoarthritis: a systematic study

Unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA) and high tibial osteotomy (HTO) may all be used to treat unicompartmental osteoarthritis, but they are often used for different patient groups. However, there is considerable overlap in indications for all three options. The aim of this review was to assess the safety and efficacy of UKA compared with TKA and HTO in unicompartmental osteoarthritis. Studies that compared UKA with either TKA or HTO were identified and included for review. For knee function and postoperative pain, UKA appeared similar to TKA and HTO at 5 years follow up. Range of motion was better in UKA compared with TKA. Complication rates after UKA and TKA appeared similar, although deep vein thrombosis was reported more often after TKA. There were more complications after HTO than UKA. Survival of UKA prostheses was approximately 85-95%, compared with at least 90% for TKA at 10 years follow up. Survivorship for HTO appeared to be less than 85%. It was not clear whether there were more revisions after UKA than TKA, but there appeared to be fewer revisions in UKA compared with HTO. UKA is considered at least as safe as TKA and HTO. For function, UKA appears to be at least as efficacious as TKA and HTO. The survival of UKA compared with TKA and HTO cannot be determined based on the available evidence.     

Imageless computer assisted versus conventional total knee replacement. A Bayesian meta-analysis of 23 comparative studies

We have undertaken a meta-analysis of the English literature, to assess the component alignment outcomes after imageless computer assisted (CAOS) total knee arthroplasty (TKA) versus conventional TKA. We reviewed 23 publications that met the inclusion criteria. Results were summarised via a Bayesian hierarchical random effects meta-analysis model. Separate analyses were conducted for prospective randomised trials alone, as well as for all randomised and observational studies. In 20 papers (4,199 TKAs) we found a reduction in outliers rate of approximately 80% in limb mechanical axis when operated with the CAOS. For the coronal femoral and tibial implants positions, the analysis included 3,058 TKAs. The analysis for the femoral implant showed a reduction in outliers rate of approximately 87% and for the tibial implant a reduction in outliers rate of approximately 80%. Imageless navigation when performing TKA improves component orientation and postoperative limb alignment. The clinical significance of these findings though has to be proven in the future.     

Surgical accuracy with the mini-subvastus total knee arthroplasty a computer tomography scan analysis of postoperative implant alignment

A total of 50 total knee arthroplasty (TKA) patients, 25 traditional and 25 minimally invasive surgical (MIS), underwent computed tomography scans to determine if a loss of accuracy in implant alignment occurred when a surgeon switched from a traditional medial parapatellar arthrotomy to a mini-subvastus surgical technique. Surgical accuracy was determined by comparing the computed tomography measured implant alignment with the surgical alignment goals. There was no loss in accuracy in the implantation of the tibial component with the mini-subvastus technique. The mean variance for the tibial coronal alignment was 1.03 degrees for the traditional TKA and 1.00 degrees for the MIS TKA (P = .183). Similarly, there was no difference in the mean variance for the posterior tibial slope (P = .054). Femoral coronal alignment was less accurate with the MIS procedure, mean variance of 1.04 degrees and 1.71 degrees for the traditional and MIS TKA, respectively (P = .045). Instrumentation and surgical technique concerns that led to this loss in accuracy were determined.     

The role of unicompartmental knee arthroplasty versus total knee arthroplasty in providing maximal performance and satisfaction

Unicondylar knee arthroplasty (UKA) and total knee arthroplasty (TKA) are both recommended for the treatment of medial compartment osteoarthritis in the varus knee. Some authors report favorable functional results and patient satisfaction from TKA on the basis of extensive, long-term success of knee arthroplasty. Others cite the arduous rehabilitation and bone loss associated with traditional knee arthroplasty, opting for UKA, especially in young, high-demand patients. This article reviews the elements of successful UKA. It emphasizes the advantages of UKA versus traditional knee arthroplasty and minimally invasive TKA.     

Factors affecting the postoperative limb alignment and clinical outcome after Oxford unicompartmental knee arthroplasty

We evaluated the postoperative mechanical axis deviation and clinical outcome according to bearing size, femoral component position, and tibial resection angle after unicompartmental knee arthroplasty (UKA). A total of 104 patients with 124 knees underwent Oxford phase 3 UKA. The overall changes in mechanical axis deviation and tibiofemoral angle were significantly different according to bearing size (P = .001 and < .001), but they were not significantly different according to the tibial resection angle and femoral component position. The postoperative mechanical axis fell into the zone C or zone 2 in 108 knees (87%) and into the zone 3 or zone 4 in 16 cases (13%). One hundred eight cases, which had the mechanical axis passing the zone C or zone 2, did not show any progression of arthritis. Limb alignment is a function of the thickness of the bearing rather than alignments of femoral and tibial implant.     

开放楔形胫骨高位截骨与单髁置换治疗膝关节内侧间室骨关节炎疗效的Meta分析

目的:系统评价开放楔形胫骨高位截骨(OWHTO)与单髁置换(UKA)治疗膝关节内侧间室骨关节炎的疗效。方法:按照Cochran协作网制定的检索策略进行检索,计算机检索Medline,Pubmed,EMbase,Cochrane Library,中国生物医学数据库,中文科技期刊数据库,万方数据库,手工检索相关的中英文骨科杂志和会议论文,检索时间截止为2018年3月。纳入OWHTO和UKA治疗膝关节内侧骨性关节炎的对照研究,对文献质量进行评价,对文献报道的术后膝关节功能、术后并发症、术后全膝关节置换术(TKA)翻修率、术后疼痛等数据进行提取,采用RevMan 5.0软件对数据进行Meta分析。结果:纳入符合标准的文献共8篇,共675例患者。Meta分析结果显示,OWHTO组与UKA组在术后膝关节HSS评分、膝评分、功能评分、Lysholm评分差异无统计学意义(P=0.32,P=0.87,P=0.22,P=0.53),OWHTO组术后关节活动度优于UKA组,差异有统计学意义(P=0.009);两组术后并发症及术后TKA翻修率差异无统计学意义(P=0.81,P=0.23)。两组患者术后膝关节疼痛无差异。结论:在治疗符合手术指征的膝关节内侧间室骨关节炎时,采用OWHTO可获得与UKA相似的膝关节评分、术后并发症和术后TKA翻修率,但是OWHTO术后关节活动度更好。     

Minimally invasive imageless computer-navigated knee surgery: initial results

The combination of imageless computer-aided surgery (CAS) and minimally invasive surgery (MIS) for total knee arthroplasty (TKA) has not been reported. This study presents the initial 30 procedures in which imageless CAS was combined with MIS for TKA by the senior author. Coronal alignment of femoral and tibial components with respect to the mechanical axis of the lower limb was measured when patients could achieve full extension. Component position was acceptable for all implants. The mean coronal tibial alignment was 90.35 degrees (range, 88 degrees -93 degrees ) and mean coronal femoral alignment 90.10 degrees (range, 88 degrees -93 degrees ) to the mechanical axis. Tourniquet time averaged 90 minutes (range, 60-118 minutes). There was no significant reduction in tourniquet time with increasing familiarity with the technique. Our results demonstrate that CAS combined with MIS for TKA maintains the accuracy of component alignment despite the minimally invasive approach. These initial results demonstrate no significant learning curve associated with the technique.     

Plain Radiograph Fails to Reflect the Alignment and Advantages of Navigation in Total Knee Arthroplasty

The study purposed to determine if a navigation in total knee arthroplasty (TKA) leads to accurate limb alignment and component position than the conventional technique as measured by full length standing radiographs and to evaluate the correlation between navigation and radiographic measurements. A total of 160 knees underwent navigation (n = 80) or conventional (n = 80) TKAs. The frontal femoral alignment was more accurate in navigation TKAs, whereas mechanical axis and frontal tibial alignment were similar in both techniques. Although the intraoperative navigation alignment showed no outliers, postoperative radiographic measure resulted as much as 20% of outliers, and there was no correlation between the two measurements. This lack of correlation and inherent limitations in measuring TKA alignment may bring to question if plain radiograph are useful to determine if alignment achieved by navigation is accurate.     

Medial unicompartmental knee arthroplasty in the ACL-deficient knee

Symptomatic osteoarthritis (OA) of the knee develops often in association with anterior cruciate ligament (ACL) deficiency. Two distinct pathologies should be recognised while considering treatment options in patients with end-stage medial compartment OA and ACL deficiency. Patients with primary ACL deficiency (usually traumatic ACL rupture) can develop secondary OA (typically presenting with symptoms of instability and pain) and these patients are typically young and active. Patients with primary end stage medial compartment OA can develop secondary ACL deficiency (usually degenerate ACL rupture) and these patients tend to be older. Treatment options in either of these patient groups include arthroscopic debridement, reconstruction of the ACL, high tibial osteotomy (HTO) with or without ACL reconstruction, unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). General opinion is that a functionally intact ACL is a fundamental prerequisite to perform a UKA. This is because previous reports showed higher failure rates when ACL was deficient, probably secondary to wear and tibial loosening. Nevertheless in some cases of ACL deficiency with end-stage medial compartment OA, UKA has been performed in isolation and recent papers confirm good short- to mid-term outcome without increased risk of implant failure. Shorter hospital stay, fewer blood transfusions, faster recovery and significantly lower risk of developing major complications like death, myocardial infarction, stroke, deep vein thrombosis (as compared to TKA) make the UKA an attractive option, especially in the older patients. On the other hand, younger patients with higher functional demands are likely to benefit from a simultaneous or staged ACL reconstruction in addition to UKA to regain knee stability. These procedures tend to be technically demanding. The main aim of this review was to provide a synopsis of the existing literature and outline an evidence-based treatment algorithm.     

Influence of limb alignment and prosthetic orientation on patient-reported clinical outcomes in total knee arthroplasty

BackgroundThe relationship between postoperative limb alignment and clinical outcomes in primary total knee arthroplasty (TKA) is well reported, but the instruments used to evaluate clinical outcomes of TKA are mainly scoring systems from the physician's viewpoint, not patient-reported outcomes. The purpose of this study was to investigate retrospectively the relationship between postoperative limb alignment and patient-reported clinical outcomes using the 2011 Knee Society Knee Scoring System (2011 KSS).MethodsThe present study included 155 knees of patients (median age, 74 years) who underwent primary TKA for varus osteoarthritis, with a mean follow-up period of 46 months. The subjects were divided into three groups based on postoperative limb alignment and femoral and tibial component positioning angle (varus, neutral, and valgus). The 2011 KSS scores were compared among the groups.ResultsFor limb alignment, the postoperative objective knee indicator score was significantly lower in the valgus group than in the varus and neutral groups, whereas no significant differences were observed in any subjective categories of the 2011 KSS. However, for the femoral component angle, functional activity scores were significantly lower in the valgus group than in the varus and neutral groups.ConclusionsThe subjective patient-reported score was not affected by the postoperative limb alignment. However, the valgus femoral component angle resulted in lower subjective functional scores. For clinical relevance, postoperative valgus positioning of femoral component should be avoided from patient-reported functional aspects during TKA.     

自制组配式截骨工具行微创膝关节置换术的早期随访结果

目的评价自制组配式截骨工具行微创全膝关节置换术的临床及早期随访效果。 方法对95例中山大学附属第一医院关节外科行全膝关节置换的重度膝关节骨关节炎的患者随机分组,分别使用自制组配式截骨工具行微创全膝关节置换术或常规全膝关节置换术。对患者术前、术后的膝关节评分法(KSS)、视觉模拟评分法(VAS)、X线影像学(下肢力线、股骨角、胫骨角和胫骨平台后倾角)进行随访对比研究,微创组和传统组之间的差异采用独立样本t检验进行比较。 结果成功随访2年以上的手术患者87例,其中微创组42例,传统组45例。微创组手术时间比传统组长(t＝9.275,P<0.05),但两组在术中出血量、输血量、引流量的比较无统计学差异(P>0.05)。两组患者均未出现皮肤坏死,深部感染和神经血管损伤的并发症。下肢力线、股骨角、胫骨角和胫骨平台后倾角比较无统计学差异(P>0.05)。术后2周内,KSS评分、VAS评分微创组要优于传统组(t＝1.518,P<0.05)(除外术后第2周KSS临床评分),但术后3月后两组比较无统计学差异(P>0.05)。 结论自制组配式截骨工具行微创全膝关节置换手术早期的临床效果要优于常规人工全膝关节置换术,两组的影像学结果相当,但尚需更长时间的随访以全面评价其临床疗效。     

Component alignment and functional outcome following computer assisted and jig based total knee arthroplasty

Background:

Incorrect positioning of the implant and improper alignment of the limb following total knee arthroplasty (TKA) can lead to rapid implant wear, loosening, and suboptimal function. Studies suggest that alignment errors of > 3° are associated with rapid failure and less satisfactory function. Computer navigated systems have been developed to enhance precision in instrumentation during surgery. The aim of the study was to compare component alignment following computer assisted surgery (CAS) and jig based TKA as well as functional outcome.

Materials and Methods:

This is a prospective study of 100 knees to compare computer-assisted TKA and jig-based surgery in relation to femoral and tibial component alignment and functional outcome. The postoperative x-rays (anteroposterior and lateral) of the knee and CT scanogram from hip to foot were obtained. The coronal alignment of the femoral and tibial components and rotational alignment of femoral component was calculated. Knee society score at 24 months was used to assess the function.

Results:

Results of our study show that mean placement of the tibial component in coronal plane (91.3037°) and sagittal planes (3.6058°) was significantly better with CAS. The difference was statistically insignificant in case of mean coronal alignment of the femoral components (90.34210° in navigation group and 90.5444° in jig group) and in case of the mean femoral condylar twist angle (external rotation 2.3406° in navigation group versus 2.3593° in jig group).

Conclusions:

A significantly improved placement of the component was found in the coronal and sagittal planes of the tibial component by CAS. The placement of the components in the other planes was comparable with the values recorded in the jig-based surgery group. Functional outcome was not significantly different.     

Robot-assisted Implantation Improves the Precision of Component Position in Minimally Invasive TKA

Minimally invasive and robot-assisted procedures have potential advantages when used for total knee arthroplasty (TKA). The purpose of this cadaveric study was to examine whether robot-assisted minimally invasive procedures improve TKA alignment after modifying the robotic techniques and instruments.Total knee arthroplasties were performed on 10 pairs of fresh cadaveric femora. Ten knees were replaced using the robot-assisted minimally invasive technique and 10 using the conventional minimally invasive technique. After prosthesis implantation, limb and prosthesis alignments were investigated by measuring mechanical axis deviation, femoral and tibial sagittal and coronal inclination, and femoral rotational alignment with 3-dimensional computed tomography scans. Postoperative alignment accuracy of the implanted prostheses was better in the robot-assisted minimally invasive TKA group than in the conventional minimally invasive TKA group as judged by the rotational alignment of the femoral component (0.7°±″.3° vs 3.6°±2.2°, respectively) and the tibial component sagittal angle (7.8°±1.1° vs 5.5°±3.6°, respectively). One sagittal inclination outlier for the tibial side existed in the robotic minimally invasive TKA group, and 2 outliers for the mechanical axis, 2 for the tibial side sagittal inclination, and 2 for the femoral rotational alignment existed in the conventional minimally invasive TKA group.Higher implanted prostheses accuracy and fewer outliers in postoperative radiographic alignments can be attained with robot-assisted TKA. Minimally invasive TKA in combination with an improved robot-assisted technique is an alternative option to compensate for the shortcomings of conventional minimally invasive TKA.