Aims. This study aimed to evaluate if total knee arthroplasty (TKA) femoral components aligned in either
The cause of dissatisfaction following total
knee arthroplasty (TKA) remains elusive. Much attention has been
focused on static
There has been a renewed interest in the importance of achievement of a neutral,
Introduction. Functional outcomes of mechanically aligned (MA) total knee arthroplasty have plateaued. The aim of this study is to find an alternative technique for implant positioning that improves functional outcomes of TKA. Methods. We prospectively randomized 100 consecutive patients undergoing TKA into two groups: in the group A an intramedullary femoral guide and an extramedullary tibial guide were used with aim to obtain a neutral traditional
Restoring the overall
The aim of
Abstract. Background. Conventional TKR aims for neutral
Introduction: I always aim for neutral
No, Neutral mechanical axis has never been regarded as “necessary” to the success of TKA. In fact it has never been established as “ideal” with published data. Tibial femoral alignment after TKA is important, but it is also an issue that we do not understand completely. Neutral
Conventional total knee arthroplasty aims to place the joint line perpendicular to the mechanical axis resulting in an overall neutral
Aims. Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) versus components placed using computer-assisted surgery targeting neutral
Introduction. Neutral
Introduction. Debate over appropriate alignment in total knee arthroplasty has become a topical subject as technology allows planned alignments that differ from a neutral mechanical axis. These surgical techniques employ patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient [1, 2]. The purpose of this study was to evaluate the correlation between post-operative limb alignment and implant migration in subjects receiving shape match derived kinematic alignment. Methods. In a randomized controlled trial comparing patient-specific cutting blocks to navigated surgery, seventeen subjects in the patient specific group had complete 1 year data. They received cruciate retaining cemented total knee replacements (Triathlon, Stryker) using patient-specific cutting blocks (OtisMed custom-fit blocks, Stryker). Intra-operatively, 6–8 tantalum markers (1 mm diameter) were inserted in the proximal tibia. Radiostereometric analysis (RSA) [3, 4] exams were performed with subjects supine on post-operative day 1 and at 6 week, 3, 6, and 12 month follow-ups with dual overhead tubes (Rad 92, Varian Medical Systems, Inc., Palo Alto, CA, USA), digital detectors (CXDI-55C, Canon Inc., Tokyo, Japan), and a uniplanar calibration box (Halifax Biomedical Inc., Mabou, NS, Canada). RSA exams were analyzed in Model-based RSA (Version 3.32, RSAcore, Leiden, The Netherlands. Post-operative limb alignment was evaluated from weight-bearing long-leg films. Results. Post-operative limb alignments ranged from 5 degrees of varus to 5 degrees of valgus. Comparing implant migration to post-operative alignment did not demonstrate a relationship between deviation from neutral
INTRODUCTION. While standard instrumentation tries to reproduce mechanical axes based on
Non-invasive assessment of lower limb
Non-invasive assessment of lower limb
In total knee replacement (TKR), neutral
INTRODUCTION. In total knee arthroplasty (TKA), the effectiveness of the
It is clear in 2013 that there is a substantial opportunity to improve patient outcomes after total knee replacement. Much attention in the last decade has focused on the apparent satisfaction gap between patients who have had total hip arthroplasty and those who have had total knee arthroplasty. Most authors note that a higher proportion of total hip patients claim to have complete satisfaction or note that they have forgotten that they had the joint replaced. The concept of “the forgotten joint replacement” is an interesting one because as surgeons and researchers we all recognise that neither total hip replacement nor total knee replacement will completely restore the native hip or knee joint's dynamic 3D biomechanics or kinematics. What the concept of the forgotten joint does tell us however is that there is a level of kinematic function above which humans cannot detect a difference with normal function. The inherent simplicity of the ball-and-socket design of the hip joint means we can achieve this level of function more reliably and reproducibly than we do in the knee joint. The knee joint presents a more difficult challenge. Recent data suggests that there is a definable trade-off in total knee prosthesis design, and likely with component position and limb alignment, between those optimised for the best kinematics and those optimised for the best durability using contemporary biomaterials (namely metal, ceramic and ultra-high molecular weight polyethylene). Given this inherent trade-off then there will be an almost never-ending debate about what constitutes “the best” overall knee implant design because that will inevitably require an individual value-judgement about the relative merit of better kinematics or better durability. Currently, we have some insights into this trade-off when we consider the role of unicompartmental knee replacement in 2013. There is little debate that unicompartmental knee replacement results in closer-to-normal knee kinematics than does total knee replacement and that many patients seem to benefit from a quicker recovery and easier rehabilitation. Data from multiple national joint registries however shows that UKR is not quite as durable as total knee replacement (mean yearly failure rate 1.53% for UKR versus 1.26% for TKR). Different surgeons and different surgeons will look at that data however and come to markedly different conclusions about how to act — some will discount the difference in durability and favor the better function/quicker recovery of UKR while other equally intelligent persons will discount the difference in function and prefer the demonstrated better durability of TKR. Like any value-judgement there is no right answer or wrong answer. As surgeons and researchers we do have opportunities in regard to surgical technique that remain unexplored. We have been limited over the past several decades by thinking primarily in terms of 2D static analyses of alignment, rotation and ligament balance. This is primarily because most assessments have been done using plain radiographs. The last decade however has seen a marked improvement in our capabilities for 3D imaging and dynamic assessment of knee joint function. The promise of computer-navigated and robotic-assisted surgery has largely remained unfulfilled as the limitations of 2D targets have come into focus. It is my belief that tomorrow's gains in total knee replacement will not involve dramatic changes in prosthesis design but instead on defining and then hitting more precise 3D targets for alignment, rotation and ligament balance in surgery. For surgeons and researchers this is an exciting time as there is a distinct opportunity to improve outcomes for millions of total knee replacement patients over the coming decades.