Objectives. We identified an unusual pattern of backside deformation on polyethylene (PE) inserts of contemporary total knee replacements (TKRs). The PE backside's margins were inferiorly deformed in TKRs with
Patients planning to undergo total knee arthroplasty (TKA), especially in Asian and Middle Eastern countries, usually expect to be able to perform activities requiring knee flexion such as sitting cross-legged or kneeling with ease after the surgery. Postoperative range of motion (ROM) can be affected by multiple factors such as the patient's gender, age, preoperative ROM, diagnosis, the surgeon's technique, the pre- and post-operative rehabilitation program, and the design of the prosthesis. Among these, the choice of the prosthesis depends on the surgeon's preference. As a result, several trials and studies have been conducted to improve postoperative ROM by modifying prosthesis design. The present study aimed to examine the results of TKA with the
Purpose. The purpose of this study is toevaluate the clinical and radiologic results after high flexiontotal knee arthroplasty, Lospa. ®. (Corentec Inc.) with 10mm cutting of posterior femoral condyle and LPS-Flex. ®. (Zimmer Inc.) with 12.5mm cutting of posterior femoral condyle.(Fig. 1). Materials and Methods. We prospectively compared 205 knees in 128 patients who underwent arthroplasty usingLospa. ®. (groupA) and 63 knees in 48 patients who underwentarthroplasty using
INTRODUCTION. The specific factors affecting wear of the ultrahigh molecular weight polyethylene (UHMWPE) tibial component of total knee replacements (TKR) are poorly understood. One recent study demonstrated that lower conforming inserts produced less wear in knee simulators. The purpose of this study is to investigate the effect of insert conformity and design on articular surface wear of postmortem retrieved UHMWPE tibial inserts. METHODS. Nineteen
Objectives. Several studies have reported elevated blood cobalt (Co) and chromium (Cr) concentrations in patients with total knee replacements (TKRs). Up to 44% of tissue samples taken from patients with failed TKRs exhibit histological evidence of metal sensitivity/ALVAL. In simulated conditions, metal particles contribute approximately 12% of total wear debris in TKR. We carried out this investigation to determine the source and quantity of metal release in TKRs. Design and Methods. We analysed 225 explanted fixed-bearing TKRs (Attune, Genesis II,
Introduction. Long term data on the survivorship of cemented total knee arthroplasty (TKA) has demonstrated excellent outcomes; however, with younger, more active patients, surgeons have a renewed interest in improved biologic fixation obtained from highly porous, cementless implants. Early designs of cementless total knees systems were fraught with high rates of failure for aseptic loosening, particularly on the tibial component. Prior studies have assessed the bone ingrowth extent for tibial tray designs reporting near 30% extent of bone ingrowth . (1,2). While these analyses were performed on implants that demonstrated unacceptably high rates of clinical failure, a paucity of data exists on the extent on bone ingrowth in contemporary implant designs with newer methods for manufacturing the porous surfaces. We sought to evaluate the extent of attached bone on retrieved cementless tibial trays to determine if patient demographics, device factors, or radiographic results correlate to the extent of bone ingrowth in these contemporary designs. Methods. Using our IRB approved retrieval database, 17 porous tibial trays were identified and separated into groups based on manufacturer: Zimmer Natural Knee (1), Zimmer
Introduction. Ideally, standardized wear testing protocols replicate the in vivo motions and forces of TKR patients. In a previous study with 30 TKR patients, two distinct in vivo gait patterns emerged, one characterized as having low anteroposterior (AP-L) motion and the other high anteroposterior (AP-H) motion. The aim of this study was to determine the effect of the two in vivo-determined gait patterns on total and backside insert wear in comparison with the ISO standard 14243-3. In order to differentiate and accurately quantify topside and backside wear, a novel technique was employed where different lanthanide tracers are incorporated into the polyethylene during manufacture. Materials and Methods. Components from the Zimmer
Introduction. Automated identification of arthroplasty implants could aid in pre-operative planning and is a task which could be facilitated through artificial intelligence (AI) and deep learning. The purpose of this study was to develop and test the performance of a deep learning system (DLS) for automated identification and classification of knee arthroplasty (KA) on radiographs. Methods. We collected 237 AP knee radiographs with equal proportions of native knees, total KA (TKA), and unicompartmental KA (UKA), as well as 274 radiographs with equal proportions of Smith & Nephew Journey and Zimmer
[Introduction]. One of the modern design total knee arthroplasty (TKA) system, the
Introduction. Total knee arthroplasty is the standard treatment for advanced knee osteoarthritis. Patient-specific instrument (PSI)has been reported by several authors using different techniques produced by implant companies. The implant manufacturers produce PSI exclusively for their own knee implants and for easy straightforward cases. However, the PSI has become very expensive and unusable as a universal or an open platform. In addition, planning the implant is done by technicians and not by surgeons and needs long waiting time before surgery (6 weeks). Methods. We proposed a new technique which is a device and method for preparing a knee joint in a patient undergoing TKA surgery of any knee implant (prosthesis). The device is patient specific, based on a method comprised of image-based 3D preoperative planning (CT, MRI or computed X-ray) to design the templates (PSI) that are used to perform the knee surgery by converting them to physical templates using computer-aided manufacturing such as computer numerical control (CNC) or additive-manufacturing technologies. The device and method are used for preparing a knee joint in a universal and open-platform fashion for any currently available knee implant. Results. All patient-specific implants and any knee implant could be produced. The technique was applied on
Purpose. To evaluate the five year Radiostereometric Analysis (RSA) results of the
Introduction:. One of the important factors for success in TKA is to achieve proper stability of the knee joint. It is currently unknown that how much joint laxity exists in mid-range to deep knee flexion, postoperatively. We hypothesized that retaining the PCL or not during TKA has an influence on the postoperative joint laxity from mid-range to deep knee flexion. The purpose of this study was to investigate the postoperative coronal joint laxity throughout the full range of motion by the 3-dimensional in vivo analysis, both in PS and CR TKA. Methods:. We implanted 5 knees with a PS TKA using a
Cementless total knee replacement (TKR) is at the present date a controversial topic. Aim of the study was to compare the effect on tibial periprosthetic bone mineral density (BMD) between different implant materials and designs. During the two-year period between January 2005 and December 2006, we analysed data of 45 patients who underwent consecutively cementless TKR (49 implants) at our Institution for primary osteoarthritis. Data was divided in 2 groups: A) 26 implants with tantalium tibial component (Zimmer
INTRODUCTION. Tibiofemoral contact at the base of the articular surface spine in posterior-stabilized total knee arthroplasty (TKA) implants can lead to spine fracture [1]. Revision TKA implants also have an articular surface spine to provide sufficient constraint when soft tissues are compromised. While some revision TKA designs have metal reinforcement in the articular surface spine, others rely solely on a polyethylene spine. This study used finite element analysis (FEA) to study the effect of metal reinforcement on stresses in the spine when subjected to posteriorly directed loading. METHODS. Two clinically successful Zimmer Biomet revision TKA designs were selected;
Total knee arthroplasty has been the main treatment method among advanced osteoarthritis (OA) patients. The main post-operative evaluation considers the level of pain, stability and range of motion (ROM). The knee flexion level is one of the most important categories in the total knee arthroplasty patient's satisfaction in Asian countries due to consistent habits of floor-sitting, squating, kneeling and cross legged sitting. In this study, we discovered that the posterior capsular release enabled the further flexion angles by 14 degrees compared to the average ROM without posterior release group. Our objective was to increase the ROM using the conventional total knee arthroplasty by the posterior capsular release. Posterior capsular release is being used in order to manage the flexion contraction. Although the high flexion method extends the contact area during flexion by extending the posterior condyle by 2mm, the main problem has been the early femoral loosening. We searched for the method to get the deep knee flexion with the conventional knee prosthesis. 122 OA patients with less than preoperative 130 flexion that underwent conventional TKAs using
Aim: To compare between the number of steps and instruments required for total knee arthroplasty (TKA) using 3 different techniques. The proposed techniques were conventional technique, conventional technique with patient-specific pin locators and CAOS technique using patient-specific templates (PST). Patients and methods: Zimmer/
Background. Constrained condylar knees are used infrequently but are successful for the treatment of the primary or revision knee with ligamentous instability and bony defect. The purpose of the present study is retrospectively analyze clinical and radiological outcome of primary and revision total knee arthroplasty with condylar constrained knee (CCK) prosthesis at a minimum of 5 years. Methods. Fourteen knees underwent total knee arthroplasty with CCK prosthesis, performed between 2003 and 2009. The average age of the patients at the time of the surgery was 71.4 years (range, 47 to 88 years). The reason for the operation was primary (osteoarthritis) in 2, revision due to aseptic loosening in 9 and infection after total knee arthroplasty in 4 knees.
At the 2010 Effort congress Prof Hernigou of France stated that you never need to template knee x-rays as there is an absolute association with patients height and implant size. Templating of the knee for size is seldom done in clinical practice but could be handy when doing revision surgery where normal anatomy has been lost. This is however difficult with digital x-rays due to enlargement problems. With this in mind we retrospectively looked at the size of knee implants inserted to see if there was any relation with patient's height and also to see if this differs in male and female patients. Material:. 2084 IB II and
Introduction. Previous studies of CoCr alloy femoral components for total knee arthroplasty (TKA) have identified 3. rd. body abrasive wear, and apparent inflammatory cell induced corrosion (ICIC) [1] as potential damage mechanisms. The association between observed surface damage on the femoral condyle and metal ion release into the surrounding tissues is currently unclear. The purpose of this study was to investigate the damage on the bearing surface in TKA femoral components recovered at autopsy and compare the damage to the metal ion concentrations in the synovial fluid. Methods. 12 autopsy TKA CoCr femoral components were collected as part of a multi-institutional orthopedic implant retrieval program. The autopsy components included Depuy Synthes Sigma Mobile Bearing (n=1) and PFC (n=1), Stryker Triathlon (n=1) and Scorpio (n=3), and Zimmer
Purpose. Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA. Method. We analyzed the shape of 114 arthritic knees at the time of primary TKA using the pre-operative CT scans. The maximum AP dimension was measured. The mediolateral dimensions were measured on the theoretical distal resection slice at three levels: the posterior region (MLP), the central region (MLC) and the anterior region (MLA) (Fig 1). The ‘aspect’ ratio (MLC/AP) ratio quantified how wide or narrow the shape is. The ‘trapezoidicity’ ratio (MLP/MLA) ratio quantified how rectangular or trapezoidal the shape is. We also quantified the medial and lateral ‘narrowing angles’ in the anterior and central zones (α and β) (Fig 2). The post-operative prosthetic overhang was calculated from CT-scan. We compared the morphological characteristics with those of twelve TKA models scanned using a three-dimensional optical scanning machine (ATOS II, GOM mbH, Braunschweig, Germany) and its photogrammetric analysis software (TRITOP, GOM mbH, Braunschweig, Germany). Results. There were significant variations in both the aspect ratio (1.16±0.07; range 0.98–1.31) and the trapezoidicity ratio (1.21±0.08; range 1.06– 1.46). Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. The multivariate analysis indicated that prosthetic overhang was correlated to the ‘aspect ratio’ (more overhang in narrow femurs, p=0.002), to the ‘trapezoidicity ratio’ (more overhang in trapezoidal femurs, p=0.002), and to the Tibio Femoral Angle (more overhang in valgus knees, p=0.035). The geometries of the twelve specimen components can be compared directly with the morphological findings of this study. Some components had excessively low trapezoidicity ratios (i.e. were too rectangular) such as DePuy LCS and Stryker Scorpio. Other designs had trapezoidicity ratios closer to anatomic values such as Zimmer