Purpose of study. To study the effect of different shoes and orthotics have on
As treatments of knee osteoarthrosis are continually refined, increasingly sophisticated methods of evaluating their biomechanical function are required. Whilst TKA shows good preoperative pain relief and survivorship, functional outcomes are sub-optimal, and research focus has shifted towards their improvement. Restoration of physiological function is a common design goal that relies on clear, detailed descriptions of native biomechanics. Historical simplifications of true biomechanisms, for example sagittal plane approximation of knee kinematics, are becoming progressively less suitable for evaluation of new technologies. The
Introduction. Tendon injuries remain challenging, secondary healing and prolonged immobilisation result in suboptimal outcome. Previous study by our group showed that demineralised bone matrix (DBM) can result in faster healing of a tendon enthesis. The aim of this study is to test different ways augmenting tendon with DBM to enhance tendon repair and regeneration. Methods. DBM strips were prepared from tibias of mature ewes. Patella,
Introduction. The low-contact stress (LCS) knee prosthesis is a mobile-bearing design with modifications to the tibial component that allow for meniscal-bearing (MB) or rotating-platform (RP). The MB design had nonconstrained anteroposterior and rotational movement, and the RP design has only nonconstrained rotational movement. The anterior soft tissues, including
This prospective longitudinal study compares the results of isolated endoscopic ACL reconstruction utilizing 4-strand hamstring tendon (HT) or
At first-stage revision surgery for infection of total knee arthroplasties, antibiotic-impregnated cement spacers are frequently implanted. Two types of cement spacers are commonly used, “static” and “articulating” cement spacers. Advocates of cement spacers state that they deliver high doses of antibiotics locally, increase patient comfort, allow mobility and provide joint stability. They also minimize contracture of collateral ligaments, thereby facilitating re-implantation of a definitive prosthesis at a later stage. The use of these cement spacers, however, are not without significant complications, including patella tendon injuries. We describe a series of three patients who sustained patella tendon injuries in infected total knee arthroplasties following the use of a static cement spacer at first-stage knee revision. The patella tendon injuries resulted in significant compromise to wound healing and knee stability requiring multiple surgeries. The mid-term function was poor with an Oxford score at 24 months ranging from 12–20 Based on our experience, we advise caution in the use of static cement spacer blocks. If they are to be used, we recommend that they should be keyed in the bone to prevent patella tendon injuries.
Introduction. With an ongoing increase in total knee arthroplasty (TKA) procedural volume, there is an increased demand to improve surgical techniques to achieve ideal outcomes. Considerations of how to improve post-operative outcomes have included preservation of the infrapatellar fat pad (IPFP). Although this structure is commonly resected during TKA procedures, there is inconsistency in the literature and among surgeons regarding whether resection or preservation of the IPFP should be achieved. Additionally, information about how surgical handling of the IPFP influences outcomes is variable. Therefore, the purpose of this systematic review was to evaluate the influence of IPFP resection and preservation on post-operative flexion, pain, Insall-Salvati Ratio (ISR), Knee Society Score (KSS),
Like all surgery, if you can see it, you can usually get the job done. This is especially true for extracting well-fixed components, as iatrogenic bone loss is a serious consideration regarding the reconstruction challenge. While reasons for revision are varied, several general principles are useful to consider during the pre and peri-operative course. Pre-operatively, forewarned is forearmed. Certain factors pre-operatively can suggest the degree of operative difficulty regarding exposure. Revisions for stiffness obviously would suggest difficulty with exposure. Revisions in knees with patellar baja are almost always challenging as the patella is difficult to evert. When revising infected knees, an exuberant synovial response can result in beefy, friable synovium that has a volume effect with decreased tissue compliance. Further, the hyperemic friable tissue bleeds easily, even with tourniquet, and is difficult to anticoagulate. Peri-operatively, the general principles to consider are as follows: 1) Don't rush exposure. Good exposure is the result of a series of deliberate and sequential steps that safely reduce tissue volume and improvement in tissue compliance. These steps include in almost all cases: a. Extend the incision as necessary, there is no call for minimally invasive revision knee surgery; b. Tenolysis of the
Many recent knee prostheses are designed aiming to the physiological knee kinematics on tibiofemoral joint, which means the femoral rollback and medial pivot motion. However, there have been few studies how to design a patellar component. Since patella and tibia are connected by a
Introduction: The mechanobiology and response of bone formation to strain under physiological loading is well established, however investigation into exceedingly soft scaffolds relative to cancellous bone is limited. In this study we designed and 3D printed mechanically-optimised low-stiffness implants, targeting specific strain ranges inducing bone formation and assessed their biological performance in a pre-clinical in vivo load-bearing tibial tuberosity advancement (TTA) model. The TTA model provides an attractive pre-clinical framework to investigate implant osseointegration within an uneven loading environment due to the dominating
A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the
The battle of revision TKA is won or lost with safe, effective, and minimally bony-destructive implant removal, protecting all ligamentous stabilisers of the knee and, most importantly, the extensor mechanism. For exposure, incisions should be long and generous to allow adequate access. A standard medial parapatellar capsular arthrotomy is preferred. A synovectomy is performed followed by debridement of all scar tissue, especially in the medial and lateral gutters. All peripatellar scar tissue is excised followed by release of scar tissue within the
A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the
Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the uncommon tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These can result in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. Two year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the using the robot to complete the procedure. Report the clinical outcomes with robotic total knee replacement at or beyond two years to demonstrate no delayed effect on expected outcome. Methods. The initial consecutive series of 65 Triathlon. TM. total knee replacements using a semi-active haptic guided system that were performed after commercialization that would be eligible for two year follow-up were reviewed. Pre-operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament,
Aim. Quadrupled hamstring anterior cruciate ligament plasties (4xHp) have been described as having a higher risk of infection than bone
Introduction. Patellar crepitus and clunk are tendofemoral-related complications predominantly associated with posterior-stabilizing (PS) total knee arthroplasty (TKA) designs [1]. Contact between the quadriceps tendon and the femoral component can cause irritation, pain, and catching of soft-tissue within the intercondylar notch (ICN). While the incidence of tendofemoral-related pathologies has been documented for some primary TKA designs, literature describing revision TKA is sparse. Revision components require a larger boss resection to accommodate a constrained post-cam and stem/sleeve attachments, which elevates the entrance to the ICN, potentially increasing the risk of crepitus. The objective of this study was to evaluate tendofemoral contact in primary and revision TKA designs, including designs susceptible to crepitus, and newer designs which aim to address design features associated with crepitus. Methods. Six PS TKA designs were evaluated during deep knee bend using a computational model of the Kansas knee simulator (Figure 1). Prior work has demonstrated that tendofemoral contact predictions from this model can differentiate between TKA patients with patellar crepitus and matched controls [2]. Incidence of crepitus of up to 14% has been reported in Insall-Burstein® II and PFC® Sigma® designs [3]. These designs, in addition to PFC® Sigma® TC3 (revision component), were included in the analyses. Primary and revision components of newer generation designs (NexGen®, Attune® and Attune® Revision) were also included. Designs were evaluated in a patient model with normal Insall-Salvati ratio and a modified model with
Introduction. Patellar resurfacing affects patellofemoral (PF) kinematics, contact mechanics, and loading on the patellar bone. Patients with total knee arthroplasty (TKA) often exhibit adaptations in movement patterns that may be linked to quadriceps deficiency and the mechanics of the reconstructed knee [1]. Previous comparisons of PF kinematics between dome and anatomic resurfacing have revealed differences in patellar sagittal plane flexion [2], but further investigation of PF joint mechanics is required to understand how these differences influence performance. The purpose of this study was to compare PF mechanics between medialized dome and medialized anatomic implants using subject-specific computational models. Methods. A high-speed stereo radiography (HSSR) system was used to capture 3D sub-mm measurement of bone and implant motion [3]. HSSR images were collected for 10 TKA patients with Attune® (DePuy Synthes, Warsaw, IN) posterior-stabilized, rotating-platform components, 5 with medialized dome and 5 with medialized anatomic patellar components (3M/7F, 62.5±6.6 years, 2.2±0.6 years post-surgery, BMI: 26.2±3.5 kg/m. 2. ), performing two activities of daily living: knee extension and lunge (Figure 1). Relative motions were tracked using Autoscoper (Brown University, Providence, RI) for implant geometries obtained from the manufacturer. A statistical shape model was used to predict the patella and track motions [4]. Subject-specific finite element models of the experiment were developed for all subjects and activities [5]. The model included implant components, patella, quadriceps,
Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the lack of tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These damages to the soft tissues resulted in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. One year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the robotic assisted procedure and resort to the use of conventional implantation. Report the clinical outcomes with robotic total knee replacement at or beyond one year to demonstrate satisfactory to excellent performance. Methods. The initial consecutive series of 100 robotic total knee replacements using a semi-active haptic guided system including 34 from the initial IDE series in 2014 and those performed after commercial approval beginning in 2016 were reviewed. Pre- operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament,
“The shortest distance between two points is a straight line.” This explains many cases of patellar maltracking, when the patellar track is visualised in three dimensions. The three-dimensional view means that rotation of the tibia and femur during flexion and extension, as well as rotational positioning of the tibial and femoral components are extremely important. As the extensor is loaded, the patella tends to “center” itself between the
Introduction. Quadriceps weakness, which is often reported following total knee arthroplasty (TKA), affects patients' abilities to perform activities of daily living [1]. Implant design features, particularly of the patella-femoral joint, influence the mechanical advantage of the extensor mechanism. This study quantifies the changes in extensor mechanism moment arms due to different patellar resurfacing options during TKA. Methods. Posterior-stabilized TKR surgery was performed on seven cadaveric knees which were subsequently mounted in the Kansas Knee Simulator (KKS) [2]. A dynamic physiological squat was simulated between 5° and 80° knee flexion at 50% body weight while knee kinematics, including the lines of action of the rectus femoris (RF) muscle and