Although stems improve initial mechanical stability in revision total knee arthroplasty (TKA), ideal indications, proper lengths and diameters, and appropriate fixation methods remain controversial. The topics of the present article include the indications, selection of lengths and diameters, and fixation methods of stems in revision TKA. The use of a stem in revision TKA can protect the juxta-articular bone. A stem cannot be a substitute for optimal component fixation; it plays an adjunctive role in transferring the loads from the compromised metaphysis to the stronger diaphysis. Proper bone surface preparation and appropriate use of the stem based on a great store of knowledge are required to support the stemmed components effectively in revision TKA. The balance between overshielding and overloading the juxta-articular bone would provide excellent structural protection. The stem length and diameter should be tailored according to patients’ anatomical characteristics and determined fixation strategy. There are two traditional methods of stem fixation including the total cementation technique and the hybrid technique with a cementless press-fit stem. Selection of a cementation technique should be based on thorough consideration of advantages and disadvantages of each technique.
Arthroplasty ; Arthroplasty, Replacement, Knee ; Cementation ; Diaphyses ; Knee ; Methods

Kinematical alignment during total knee arthroplasty is an emerging process, and draws more and more attentions from scholars. Knee joint is close to normal joint after TKA through kinematical alighment, which has good clinical results and functional scores, and not increase failure probility. Thus, it may increase joint stress of patella-femur joint, lead to patellar maltracking and increase abrasion. The paper summarized defination and basical principle, operative method, clinical outcomes and deficiency of kinematical alignment during total knee arthroplasty, in order to choose a better way for kinematical alignment during total knee arthroplasty.
Arthroplasty, Replacement, Knee ; methods ; Biomechanical Phenomena ; Humans

BACKGROUNDControversy still exists regarding whether medial parapatellar approach (MP) or midvastus approach (MV) is preferable in total knee arthroplasty (TKA) up to now. The aim of this meta-analysis was to compare the clinical and radiological outcomes following the MV or MP for TKA.

METHODSA comprehensive search of unrestricted-language literature of all studies comparing MP with MV was conducted through the electronic literature databases of PubMed, EMBASE, Cochrane Library, CNKI, VIP, and WANFANG. Retrieval time was from the time when databases were built to October 2013. Manual search of relevant trials, reviews, and related articles was also performed. Outcomes of interest included postoperative knee extensor and flexor function, postoperative pain, patella tilt, and complications. Relative risk (RR) and weighted mean differences (WMD) from each trial were pooled using random-effects or fixed-effects model depending on the heterogeneity of the included studies. A subgroup analysis or a sensitivity analysis was conducted to explore the potential source of heterogeneity when necessary.

RESULTSTwenty-one randomized controlled trials (RCTs) comprising 1 188 patients (1 450 knees) were eligible. Our results showed that MV was associated with better early postoperative extension (WMD = -1.26, 95% CI -2.36 to -0.16, P = 0.02) and flexion (WMD = 10.13, 95% CI 5.36 to 14.90, P < 0.01), less postoperative pain (WMD = -0.21, 95% CI -0.34 to -0.07, P = 0.002) , and no greater risk for complications than MP. The patella tilt did not differ significantly between the two groups (WMD = -0.70, 95% CI -1.94 to 0.54, P = 0.27).

CONCLUSIONSMV may be a better approach than MP, as it improves postoperative early joint function and decreases pain. Future multi-center randomized controlled studies with large sample sizes are required to verify the current findings.

BACKGROUND: Computer-assisted orthopaedic surgery (CAOS) improves accuracy and reduces outliers in total knee arthroplasty (TKA). However, during the evaluation of CAOS systems, the error generated by the guidance system (hardware and software) has been generally overlooked. Limited information is available on the accuracy and precision of specific CAOS systems with regard to intraoperative final resection measurements. The purpose of this study was to assess the accuracy and precision of a next generation CAOS system and investigate the impact of extra-articular deformity on the system-level errors generated during intraoperative resection measurement. METHODS: TKA surgeries were performed on twenty-eight artificial knee inserts with various types of extra-articular deformity (12 neutral, 12 varus, and 4 valgus). Surgical resection parameters (resection depths and alignment angles) were compared between postoperative three-dimensional (3D) scan-based measurements and intraoperative CAOS measurements. Using the 3D scan-based measurements as control, the accuracy (mean error) and precision (associated standard deviation) of the CAOS system were assessed. The impact of extra-articular deformity on the CAOS system measurement errors was also investigated. RESULTS: The pooled mean unsigned errors generated by the CAOS system were equal or less than 0.61 mm and 0.64degrees for resection depths and alignment angles, respectively. No clinically meaningful biases were found in the measurements of resection depths (< 0.5 mm) and alignment angles (< 0.5degrees). Extra-articular deformity did not show significant effect on the measurement errors generated by the CAOS system investigated. CONCLUSIONS: This study presented a set of methodology and workflow to assess the system-level accuracy and precision of CAOS systems. The data demonstrated that the CAOS system investigated can offer accurate and precise intraoperative measurements of TKA resection parameters, regardless of the presence of extra-articular deformity in the knee.
Arthroplasty, Replacement, Knee/*methods ; Reproducibility of Results ; *Surgery, Computer-Assisted

PURPOSE: We devised an intraoperatively identifiable mechanical axis (IIMA) as a reference of alignment in total knee arthroplasty (TKA). MATERIALS AND METHODS: Between February 2010 and January 2011, primary TKAs were consecutively performed on 672 patients (1007 knees) using an IIMA as a reference in the coronal plane. RESULTS: The alignment of the lower extremity improved from a mean of 11.4+/-6.7degrees (-10.3-34.4degrees) of varus preop. to 0.7+/-3.5degrees (-5.2-8.6degrees) immediately after surgery. Mean alignment of the femoral component in the coronal plane was 89.3+/-2.3degrees (83.4-97.2degrees) postop. and mean alignment of the tibial component was 90.4+/-2.2degrees (85.1-94.2degrees) postop. CONCLUSION: This study showed that IIMA could be of considerable value as a new guider of alignment that is easily accessible and highly effective during total knee arthroplasty.
Arthroplasty, Replacement, Knee/*methods ; Femur/surgery ; Humans ; Tibia/surgery

Computer assisted surgery (CAS) was used to improve the positioning of implants during total knee arthroplasty (TKA). Most studies have reported that computer assisted navigation reduced the outliers of alignment and component malpositioning. However, additional sophisticated studies are necessary to determine if the improvement of alignment will improve long-term clinical results and increase the survival rate of the implant. Knowledge of CAS-TKA technology and understanding the advantages and limitations of navigation are crucial to the successful application of the CAS technique in TKA. In this article, we review the components of navigation, classification of the system, surgical method, potential error, clinical results, advantages, and disadvantages.
Arthroplasty, Replacement, Knee/*methods ; Humans ; *Surgery, Computer-Assisted

Arthroplasty, Replacement, Knee ; adverse effects ; methods ; Humans ; Postoperative Complications ; therapy

INTRODUCTION: Numerous methods of medial soft tissue release for severe varus deformity during total knee arthroplasty (TKA) have been reported. These include tibial stripping of the superficial medial collateral ligament (MCL), pie-crusting technique, and medial epicondylar osteotomy. However, there are inherent disadvantages in these techniques. Authors hereby present a novel quantitative method: femoral origin release of the medial collateral ligament (FORM). SURGICAL TECHNIQUE: For medial tightness remaining even after the release of the deep MCL and semimembranosus, the FORM is initiated with identification of the femoral insertion area of the MCL with the knee in flexion. Starting from the most posterior part of the femoral insertion, one third of the MCL femoral insertion is released from its attachment. If necessary, further sequential medial release is performed. MATERIALS AND METHODS: Seventeen knees that underwent the FORM were evaluated for radiological and clinical outcomes. RESULTS: Regardless of the extent of the FORM, no knees showed residual valgus instability at 24 weeks after surgery. CONCLUSIONS: As the FORM is performed in a stepwise manner, fine adjustment during medial release might be beneficial to prevent inadvertent over-release of the medial structures of the knee.
Arthroplasty ; Arthroplasty, Replacement, Knee ; Collateral Ligaments ; Congenital Abnormalities ; Knee ; Methods ; Osteotomy

PURPOSE: There are many methods to reduce massive bleeding during total knee arthroplasty (TKA). In our study, tranexamic acid and neutral drainage were used to decrease total blood loss. MATERIALS AND METHODS: The study was performed on 97 TKA patients from March 2012 to January 2013. In the study group, tranexamic acid was administered and neutral drainage was applied. The study group had group I (unilateral, n=29) and group III (bilateral, n=17). The control group had group II (unilateral, n=35) and group IV (bilateral, n=16). RESULTS: In group I, the drainage volume on the 1st and 2nd postoperative days and the total drainage decreased with statistical significance (p<0.05). Between group III and group IV, group III had less drainage volume. In group III, the drainage volume on the 1st postoperative day and total drainage volume decreased statistically significantly (p<0.05). Between groups I and II, total blood loss showed no statistically significant difference, whereas between groups III and IV, the value was significantly different. CONCLUSIONS: Intravenous administration of tranexamic acid with neutral drainage for 3 postoperative hours is a recommendable method because it can be helpful in reducing total blood loss in bilateral TKA.
Administration, Intravenous ; Arthroplasty ; Arthroplasty, Replacement, Knee ; Drainage ; Hemorrhage ; Humans ; Knee ; Methods ; Tranexamic Acid

The correct alignment of the knee joint is considered to be one of the most influential factors in determining the long-term prognosis after total knee arthroplasty(TKA). In order to achieve the correct alignment goal, many different alignment concepts and surgical techniques have been established. For example, mechanical alignment(MA), kinematic alignment(KA) and functional alignment(FA) have their own characteristics. MA focuses on achieving neutral alignment of the limbs, parallel and equal bone gaps during stretching and flexion. KA aims to restore the patient 's natural joint line, make the joint level and angle normal and improve the physiological soft tissue balance, and strive to reproduce the normal knee function;among them, functional alignment(FA) developed with robot-assisted surgery technology is a relatively new alignment concept. It not only considers the alignment of the body, but also aims to achieve flexion and extension balance, while respecting the native soft tissue capsule. It not only restores the plane and slope of the in situ joint line accurately during the operation, but also takes into account the balance of soft tissue, which is a better alignment method. Therefore, it is of great significance to correctly construct the lower limb force line of patients, which is helpful to restore knee joint function, relieve pain symptoms and prolong the service life of prosthesi. However, compared with traditional TKA, the operation time of robot-assisted FA-TKA is prolonged, which means that the probability of postoperative infection will be greater. At present, most studies of FA technology report short-term results, and the long-term efficacy of patients is not clear. Therefore, long-term research results are needed to support the application of this technology. Therefore, the author makes a review on the research status of functional alignment.
Humans ; Arthroplasty, Replacement, Knee/methods* ; Robotics ; Knee Joint/surgery* ; Osteoarthritis, Knee/surgery* ; Knee ; Knee Prosthesis ; Biomechanical Phenomena