Soft tissue balance measurement in posterior-stabilized total knee arthroplasty with a navigation system

Using a tensor for total knee arthroplasty (TKA) that is designed to facilitate soft tissue balance measurements with a reduced patello-femoral joint, we intraoperatively measured the joint gap and ligament balance of 30 osteoarthritic knees at extension and 90 degrees flexion, with the patella both everted and reduced, while performing primary posterior-stabilized TKA. At the same time, we performed the same measurements with a navigation system and identified correlations between this system and the tensor. Specifically, the R(2) values obtained with the knee in extension and 90 degrees flexion were higher with the patella reduced than with the patella everted. We thereby suggest that the navigation system we describe is reliable for obtaining accurate measurements of soft tissue balancing with the patella reduced.     

Posterior-stabilized versus cruciate-retaining total knee arthroplasty: balancing the gap

A prospective, randomized, double-blind trial was carried out to compare cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasties (TKAs). A total of 40 knees were randomized to receive either a NexGen CR (Zimmer, Warsaw, IN) or a Legacy PS (Zimmer, Warsaw, IN) TKA. All knees were implanted with identical surgical technique, making sure to balance precisely the flexion-extension gaps before implantation of the components. At 2-year follow-up, there was no difference between the CR and the PS TKAs with respect to their Knee Society clinical, functional, and radiographic scores. These findings suggest that with careful attention to surgical technique and balancing the knee, orthopaedic surgeons should expect similar results whether they use a CR or PS TKA.     

屈曲挛缩畸形膝关节置换的软组织平衡

目的：探讨屈曲挛缩畸形的膝关节行关节置换的方法,重点关注术中膝关节周围软组织平衡的方法。技巧及术后疗效。方法：自2010年6月～2012年6月共收治晚期膝关节疾病合并屈曲挛缩畸形患者156例,213膝,采取人工膝关节置换进行治疗,分别记录术前术后膝关节畸形程度,HSS评分,活动范围。并进行比较。本组病例平均年龄60．2岁（44～81岁）,女92例136膝,男64例77膝。膝骨性关节炎85例,类风湿性关节炎58例,创伤性关节炎13例。膝关节活动范围平均52．6°（33．5°～94．1°）。本组病例轻度屈曲畸形：83例117膝,中度屈曲畸形：58例76膝,重度屈曲畸形：15例20膝。平均屈曲畸形程度：45．8°。每例患者均进行术前及术后1年HSS评分进行疗效评价。结果：所有病例获得随访,屈曲挛缩畸形均得到改善,膝关节HSS评分由术前20．7分提高到术后平均73．6分。膝关节活动范围术前平均52．6°提高到术后平均92．7°。结论：晚期膝关节病所致的屈曲挛缩畸形的膝关节行膝关节置换术,除了在术中注意准确截骨外,应着重注意软组织松解,调整力线。     

Factors affecting flexion gap tightness in cruciate-retaining total knee arthroplasty

With the exception of flexion gap tightness, which is common in cruciate-retaining (CR) total knee arthroplasty (TKA), the risk factors of flexion gap tightness have not been described. This retrospective study characterized factors that are associated with flexion gap tightness in CR TKA. Data on 203 consecutive knees that underwent CR TKA were reviewed. The prevalence rate of flexion gap tightness was 21.1%. By logistic regression analysis after adjusting for age, preoperative flexion contracture, and referencing method used for femoral sizing, insufficient tibial slope remained a significant independent risk factor of flexion gap tightness. Although excessive tibial slope should be avoided, the findings of the present study demonstrate that the risk of flexion gap tightness can be reduced by increasing the tibial slope in CR TKA.     

Soft tissue balance measurement in anterior cruciate ligament-resected knee joint: cadaveric study as a model for cruciate-retaining total knee arthroplasty

Background The soft tissue balancing procedure remains a difficult issue during total knee arthroplasty, as much depends on the surgeon's “feel.” Although computer-assisted navigation technology has been attempting to evaluate the joint stability, we have no definitive answer to an ideal soft tissue balance of the knee joint. The purpose of the present study was to determine the soft tissue balance in an anterior cruciate ligament (ACL)-resected normal knee joint throughout the range of knee flexion, which may provide reference data for cruciate-retaining total knee arthroplasty (TKA). Methods We investigated joint stability in 10 ACL-resected normal cadaver knees throughout the range of flexion under consistent joint distraction force using a specially developed tensioning device for TKA. We measured both medial and lateral joint gaps as the separation distance between the articular surfaces with 40 lb (18.7 kg) of joint distraction force. Results Both medial and lateral joint gaps at 0° of flexion were significantly smaller than those at other flexion angles. The medial joint gap was almost consistent during knee flexion; however, the lateral joint gap increased with knee flexion and showed a significantly larger value at 60°–120° of flexion than the medial joint gap. Conclusions These characteristics of joint stability in the ACL-resected normal knee need to be taken into consideration in soft tissue balancing during cruciate-retaining TKA.     

个体化的软组织平衡技术在膝外翻全膝关节置换术中的应用

目的探讨在膝外翻畸形全膝关节置换(TKA)术中应用个体化软组织平衡技术的临床效果及手术方法。方法膝外翻患者,术前X线测量股骨和胫骨解剖轴线夹角(FTA角),根据膝外翻畸形Keblish分级(轻度<15°;中度15°～30°;重度>30°),分为轻、中、重三级并认真评估患者软组织状况。软组织平衡术分为三步,第一步切开关节囊前行髂胫束苹果派样延长,第二步自胫骨结节骨膜下松解骼胫束止点和外侧副韧带,第三步自股骨侧松解外侧副韧带及后外侧关节囊。手术方法采用髌旁外侧入路,不同分级个体化的应用上述3步软组织平衡方法行TKA手术。术后测量FTA角,术后定期随访行美国膝关节协会评价标准KSS评分及功能评分与术前比较,评价手术效果。结果 2008年1月～2011年12月,20例(23膝)膝外翻患者,Keblish分级轻度8例8膝,中度7例10膝,重度5例5膝;轻、中、重三级患者应用个体化的软组织平衡方法实施TKA手术;所有患者均获得随访,随访时间6～48个月。术前术后FTA角及KSS评分、功能评分结果经SPSS14.0统计学软件做配对样本t检验,差异均有统计学意义(P<0.01)。全部患者术后外翻畸形均得到完全矫正,关节稳定性良好。结论膝外翻畸形TKA术中选择个体化的软组织平衡方案,可以有效地矫正软组织失衡而获得满意的临床效果,同时又可以避免矫枉过正导致术后关节不稳。     

Soft-tissue balancing in total knee arthroplasty: cruciate-retaining versus posterior-stabilised,and measured-resection versus gap technique

Purpose

The purpose of this study was to prove the hypothesis that soft tissues are well balanced using the gap technique with a navigation system in cruciate-retaining (CR) and posterior-stabilised (PS) total knee arthroplasty (TKA), leading to better clinical outcomes compared with the measured-resection technique.

Methods

One hundred and thirty-five TKAs (90 CR and 45 PS) were performed in patients with varus-type osteoarthritis using the gap technique guided by the offset-type tensor and a navigation system. Soft-tissue balance (joint-component gap and ligament balance) were intraoperatively assessed with the tensor under 40 lb of joint-distraction force. The achievement in the equalised rectangular gap at extension and flexion was assessed and retrospectively compared with the previous series in which the measured-resection technique was used (20 CR and 100 PS TKAs). In addition, clinical outcomes, including range of motion and Knee Society Score were assessed at a minimum two year follow-up.

Results

In achieving equalised rectangular gaps at extension and flexion, CR TKAs met criteria in more cases [66.7 % (64/90) vs. 44.4 % (20/45) of PS TKA] with the gap technique, which was superior to that with the measured-resection technique [50.0 % (10/20) of CR TKA and 28.0 % (28/100) of PS TKA]. However, clinical outcomes showed no significant differences among groups at minimum two year follow-up.

Conclusions

The superiority of CR TKA with the gap technique in achieving equalised rectangular gaps at extension and flexion does not directly reflect two year postoperative clinical outcomes.     

Computer-assisted navigation for cruciate-retaining total knee arthroplasty in patients with advanced valgus arthritic knees

BackgroundThe valgus arthritic knee is a complex deformity involving both soft tissue and bony problems that significantly affect the positioning of the components for, and decrease the accuracy of, reconstructed alignment in total knee arthroplasty (TKA). The unique bony deformity and soft tissue problem makes the use of conventional mechanical instrumentation difficult and leads to unsatisfactory results.PurposeThe purpose of this study was to investigate the effect of computer-assisted navigation for TKA on the postoperative mechanical axis, component alignment, and functional outcomes in the arthritic knee with genu valgus deformity.MethodsFrom January 2003 to August 2009, 24 patients (24 knees) with advanced valgus knee arthritis who underwent computer-assisted navigation for cruciate-retaining TKA were retrospectively reviewed. The accuracy of the postoperative mechanical axis and component alignment, and functional outcomes were assessed.ResultsThe mean postoperative mechanical axis was 180.2° (range, 178.1–182.5°). All patients achieved the targeted goal of a leg axis within 3° of the neutral axis. The joint line was not substantially elevated. No patient required conversion to a constrained component to achieve stability. At a mean follow-up of 45.5 months, the Hospital for Special Surgery (HSS) knee score improved from a mean preoperative score of 55.6 to 92.8 postoperatively. The International Knee Society (IKS) clinical score improved from 42.2 to 95.9. The IKS for pain improved from 15.4 to 47.1, and the IKS knee function score improved from 35.8 to 95.4.ConclusionComputer-assisted navigation for TKA is a useful alternative technique for advanced valgus knee arthritis where accurate restoration of the joint line, proper alignment of the limb and prosthetic components, and meticulous soft tissue balancing may be challenging because of bony deformities and soft tissue contractures.     

The influence of patella height on soft tissue balance in cruciate-retaining and posterior-stabilised total knee arthroplasty

Purpose

Although the patella reduced or everted position has recently been recognised as an important factor influencing soft tissue balance during assessment in total knee arthroplasty (TKA), the influence of patella height on soft tissue balance has not been well addressed. Therefore, the relationship between soft tissue balance and patella height was investigated and differences between cruciate-retaining (CR) and posterior-stabilised (PS) TKA were compared.

Methods

Forty consecutive patients blinded to the type of implant received, were randomised prospectively. Using lateral radiographs, pre-operative patella height was measured. Using an offset-type tensor designed to measure the soft tissue balance with a reduced patellofemoral (PF) joint and femoral component in place, soft tissue balance was intra-operatively assessed in CR TKA (n = 20) and PS TKA (n = 20) in osteoarthritic patients. The joint component gap and varus ligament balance at zero, ten, 45, 90 and 135° of knee flexion with the patella reduced were measured.

Results

In PS TKA, the joint component gap positively correlated with patella height at 90 and 135° of knee flexion. However, there was no correlation between joint component gap and patella height at other flexion angles in PS TKA and any flexion angle in CR TKA. Varus ligament balance showed no significant correlation with patella height in either CR or PS TKA.

Conclusion

Analysis of soft tissue balance and patella height only showed a positive correlation in joint component gap at a high flexion angle (90 and 135°) in PS TKA but not in other parameters examined. Pre-operative measurement of patella height may be an important factor for predicting an intra-operative flexion gap in PS TKA.     

人工髋关节置换术中的软组织平衡问题

[目的]通过对人工髋关节置换术后脱位的病例进行回顾性的分析。[方法]对本院在1992年1月~2002年3月间行人工髋关节置换术术后脱位的12例病例资料进行回顾性分析。[结果]12例病人中,有9例属软组织松弛,张力失衡所致,占75%。[结论]髋关节周围软组织松弛、张力失衡是术后脱位的主要原因;完善髋关节置换术中的软组织平衡技术,可降低术后脱位的发生率。     

Intraoperative soft tissue balance reflects minimum 5-year midterm outcomes in cruciate-retaining and posterior-stabilized total knee arthroplasty

With the use of an offset type tensor for total knee arthroplasties (TKAs), intraoperative soft tissue balance including the joint component gap and ligament balance was measured in 41 varus-type osteoarthritic patients (19 cruciate-retaining [CR] TKAs and 22 posterior-stabilized [PS] TKAs), and the correlations between the intraoperative values and the postoperative values assessed by stress radiographs at extension and flexion were examined at a minimum 5-year follow-up. In CR TKAs, the postoperative soft tissue balances at both angles were significantly correlated with the intraoperative values. In PS TKAs, the postoperative soft tissue balances at extension, not flexion, were significantly correlated with the intraoperative values. In conclusion, the intraoperative condition of the soft tissue balance reflected the postoperative values especially in CR TKAs even at 5-year midterm follow-ups.     

计算机导航间隙平衡技术对全膝关节置换术后患者下肢恢复的影响

目的:探讨计算机导航间隙平衡技术对全膝关节置换术患者术后下肢功能恢复的影响.方法:回顾性分析2018年7月至2019年6月接受全膝关节置换术的106例膝关节骨性关节炎(osteoarthritis,OA)患者的临床资料,根据全膝关节置换术中截骨技术不同分为测量截骨组和间隙平衡组.测量截骨组61例,男24例,女37例;年...     

Twelve years' experience with posterior cruciate-retaining total knee arthroplasty

The posterior cruciate ligament can be retained with advantage during routine total knee arthroplasty. This ligament is virtually always intact and functioning, even in rheumatoid patients. It is an important biologic stabilizer of the knee, capable of absorbing anterior-posterior shearing forces that otherwise must be borne by a constrained prosthesis and hence by the bone-cement interface. Its presence allows maintenance of the normal kinematics of the knee. Roll-back of the femur on the tibia can occur, enhancing flexion and improving the quadriceps moment. Substitution of the posterior cruciate ligament with the addition of prosthetic constraint will increase bone-cement reaction forces. These prostheses also require significant intercondylar femoral bone stock resection. The average range of motion of the early cruciate sacrificing design used in Insall's series was 94 degrees, 10 degrees or more less than now routinely seen with cruciate preservation. The bone-cement interface of the early total condylar knee with limited range of motion absorbed less force than it potentially might encounter with greater range of motion and increased function. Predictably, at long-term follow-up examination the newer cruciate-substituting prostheses that allow more physiologic range of motion might show higher radiolucent line rates and higher loosening rates than their cruciate-preserving counterparts. Only this information can settle the argument over whether the posterior cruciate ligament should be preserved, and if the objective is a knee with maximum flexion and maximum functional capability.     

Soft tissue balancing in total condylar knee arthroplasty

Soft tissue balancing and correct bone cuts are an entity in correcting malalignment in total knee arthroplasty, and cannot be considered isolated. Distinct bony deformations/deviations need enlarged soft tissue management. The extent of resection of the bone stock has to be planned exactly before the operation. Exact soft tissue balancing is necessary to stabilize the corrected knee. Soft tissue balancing has to be done primarily on the side of the contracture by lengthening of the shortened and contracted structures. After balancing the ligaments should have the same tension in extension and flexion together with the same height of the extension and flexion gap. Because of the classic resection of the tibial head, the femoral resection must follow the Insall-Line, that means 3 degrees to 5 degrees outer rotation in relation to the condyles. Only in this way a symmetric flexion gap can be achieved in combination with ligamentous stability in extension and flexion.     

In vivo stability of total knee arthroplasty using a navigation system

The aim of this study was to evaluate in vivo stability for mediolateral laxity in extension and anteroposterior laxity in 90° of flexion and to correlate these and the range of motion (ROM) in 42 total knee arthroplasties (TKA) performed using a navigation system, with a minimum 1-year follow-up. The following parameters were measured at the final follow-up: mediolateral laxity in extension and anteroposterior laxity in 90° of flexion as determined by stress radiographs and a Telos arthrometer, modified HSS scores (excluding laxity and range of motion) and the range of motion (ROM). The mean modified HSS score was 82% of 82 maximum allowable points, and the mean postoperative ROM was 128.1±10.4°. Mean medial laxity was 3.5±1.4°, mean lateral laxity was 4.4±2.2° and mean anteroposterior laxity was 7.1±4.1 mm. We found no significant correlation between mediolateral laxity and postoperative ROM. However, a significant correlation was found between postoperative ROM and anteroposterior laxity. In conclusion, the use of a navigation system in TKA assists the surgeon to achieve good in vivo stability. Short-term clinical results are promising.

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Résumé Le but de cette étude est d’évaluer la stabilité latérale en extension et la stabilité antéropostérieure en flexion à 90° des PTG en corrélation avec le degré de mobilité sur 42 genoux mis en place en utilisant un système de navigation, avec un minimum de suivi d’un an. La laxité médio-latérale en extension, la laxité antéropostérieure en flexion à 90° ont été évaluées en utilisant des radiographies en stress (arthromètre Télos), a également été utilisé le score HSS et l’évaluation du degré de flexion du genou au dernier recul. Le score HSS était dans plus de 82% des cas supérieur à 82 points avec une flexion moyenne du genou de 128,1±10,4°. La laxité interne de la mesure a été de 3,5±1,4°, la laxité externe de 4,4±2,2° et la laxité antéropostérieure de 7,1±4,1 mm. Nous n’avons pas trouvé de corrélation significative entre la laxité latérale et le degré de flexion du genou. Cependant nous avons retrouvé une corrélation significative entre le degré de flexion du genou et la laxité antéropostérieure alors qu’il n’y avait pas de corrélation entre laxité médio-latérale et la mobilité. En conclusion, l’utilisation d’un système de navigation dans la mise en place d’une prothèse totale du genou est une aide certaine pour obtenir une meilleure stabilité et des résultats à court terme prometteurs.

     

Proprioception, kinesthesia, and balance after total knee arthroplasty with cruciate-retaining and posterior stabilized prostheses

BACKGROUND: The effect of total knee arthroplasty on proprioception, kinesthesia, and postural control remains controversial. It is argued that retaining the posterior cruciate ligament may help to preserve these sensorimotor functions and improve the longevity of the prosthesis and the functional outcome. We performed a prospective, randomized study to assess proprioception, kinesthesia, and balance following total knee arthroplasty with cruciate-retaining and posterior stabilized prostheses. METHODS: Twenty patients scheduled to undergo total knee arthroplasty were randomly assigned to receive either a cruciate-retaining or a posterior stabilized prosthesis. Joint-position sense, the threshold to detect joint motion, and the subject's ability to balance on an unstable platform were assessed prior to and at least six months after the operation. Paired two-tailed t tests (with a level of significance of p < 0.05) were used to assess the effect of the arthroplasty on the preoperative measures for all subjects. Analysis of covariance was performed to identify the effects of prosthetic design. RESULTS: Following total knee arthroplasty, patients detected motion significantly faster and reproduced joint position with less error. The balance index also improved significantly from the preoperative to the postoperative evaluation. The group treated with the posterior stabilized prosthesis more accurately reproduced joint position when the knee was extended from a flexed position. CONCLUSIONS: Total knee arthroplasty results in mild improvements in proprioception, kinesthesia, and balance. These changes may result from the retensioned capsuloligamentous structures and reduced pain and inflammation. Retention of the posterior cruciate ligament does not appear to significantly improve proprioception and balance compared with those functions in patients with a posterior stabilized total knee design.     

间隙平衡技术在全膝关节置换术中应用的中期随访研究

[目的]分析间隙平衡技术在全膝关节置换(total knee arthroplasty,TKA)术中应用的临床效果及注意事项.[方法]回顾分析2004年3月～ 2006年3月应用间隙平衡(gap balancing,GB)技术的TKA患者45例(49膝),男16例,女29例,手术时年龄52 ～ 79岁,平均62.4岁.另取同期采用测量截骨(measured resection,MR)技术的TKA患者70例(76膝)设为对照组.比较分析两组患者的手术情况、影像学、膝关节功能恢复情况.[结果] 115例患者均获随访,时间6～8年,平均6.8年.GB组单膝手术时间、胫骨截骨量、股骨截骨量均明显低于MR组,术中股骨假体相对外上髁解剖轴内旋角度GB组大于MR组(P＜0.05).TKA术后两组患者髌骨外倾角度存在显著性差异(P＜0.05),GB组明显大于MR组.术后膝关节KSS、VAS评分及并发症发生率两组比较均无显著性差异(P＞0.05).[结论] TKA术中应用GB技术手术时间短,截骨量少,股骨假体相对外上髁解剖轴内旋和髌骨倾斜角度较大,中期随访临床效果和MR技术无明显差异,GB技术应避免内侧软组织过度松解,预防术后屈曲失稳及髌股关节并发症.     

Handheld navigation in total knee arthroplasty

Handheld navigation is now available for use in total knee arthroplasty, allowing for precision cuts of the distal femur and proximal tibia. By using inertial sensors and accelerometers, the handheld navigation unit is able to provide real-time, intraoperative information about alignment without additional incisions or arrays, line-of-sight issues, or the large capital expense associated with large console navigation systems. This handheld navigation unit reduces alignment outliers commonly seen with conventional guides, potentially leading to benefits in knee function and implant longevity.