Introduction. Soft tissue releases are often required to correct deformity and achieve gap balance in total knee arthroplasty (TKA). However, the process of releasing soft tissues can be subjective and highly variable and is often perceived as an ‘art’ in TKA surgery. Releasing soft tissues also increases the risk of iatrogenic injury and may be detrimental to the mechanically sensitive afferent nerve fibers which participate in the regulation of knee joint stability. Measured resection TKA approaches typically rely on making bone cuts based off of generic alignment strategies and then releasing soft tissue afterwards to balance gaps. Conversely,
Obtaining a balanced flexion gap with correct
femoral component rotation is one of the prerequisites for a successful
outcome after total knee replacement (TKR). Different techniques
for achieving this have been described. In this study we prospectively
compared
The two distinct surgical techniques for total knee arthroplasty (TKA) are
Most of in vivo kinematic studies of total knee arthroplasty (TKA) have reported on varus knee. TKA for the valgus knee deformity is a surgical challenge. The purposes of the current study are to analyze the in vivo kinematic motion and to compare kinematic patterns between weight-bearing (WB) and non-weight-bearing (NWB) knee flexion in posterior-stabilized (PS) fixed-bearing TKA with pre-operative valgus deformity. A total of sixteen valgus knees in 12 cases that underwent TKA with Scorpio NRG PS knee prosthesis operated by modified gap balancing technique were evaluated. The mean preoperative femorotibial angle (FTA) was 156°±4.2°. During the surgery, distal femur and proximal tibia was cut perpendicular to the mechanical axis of each bone. After excision of the menisci and cruciate ligaments, balancer (Stryker joint dependent kinematics balancer) was inserted into the gap between both bones for evaluation of extension gap. Lateral release was performed in extension. Iliotibial bundle (ITB) was released from Gerdy tubercle then posterolateral capsule was released at the level of the proximal tibial cut surface. If still unbalanced, pie-crust ITB from inside-out was added at 1 cm above joint line until an even lateral and medial gap had been achieved. Flexion gap balance was obtained predominantly by the bone cut of the posterior femoral condyle. Good postoperative stability in extension and flexion was confirmed by stress roentgenogram and axial radiography of the distal femur. We evaluated the in vivo kinematics of the knee using fluoroscopy and femorotibial translation relative to the tibial tray using a 2-dimentional to 3-dimensional registration technique.Backgrounds
Methods
Aims. Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA. Methods. A total of 220 consecutive primary TKAs between May 2016 and November 2018, performed by a single surgeon, were reviewed. Planned coronal plane component alignment and overall limb alignment were all 0° to the mechanical axis; tibial posterior slope was 2°; and polyethylene thickness was 9 mm. For RA-TKA, individual component position was adjusted to assist
Postoperative functional outcomes and patients’ satisfaction after total knee arthroplasty are associated with postoperative range of motion. Severe deformities require surgical correction such as soft tissue release and appropriate bone resection. The goal of surgery is to correct the contracture and bring the knee to good range of motion. Using
Introduction. Instability is a common reason for revision after total knee arthroplasty. A balanced flexion gap is likely to enhance stability throughout the arc of motion. This is achieved differently by the gap balancing and measured resection techniques. Given similar clinical results with the two techniques, one would expect similar rotation of the femoral component in the axial plane. We assessed posterior-stabilized femoral component axial rotation placed with computer navigation and a modified gap balancing technique. We hypothesized that there would be little variation in rotation. Methods. 90 surgeons from 8 countries used a modified
Introduction/Aim. Mid-flexion instability is a well-documented, but often poorly understood cause of failure of TKA. NAVIO robotic-assisted TKA (RA-TKA) offers a novel, integrative approach as a planning, execution as well as an evaluation tool in TKA surgery. RA-TKA provides a hybrid planning technique of measured resection and gap balancing- generating a predictive soft-tissue balance model, prior to making cuts. Concurrently, the system uses a semi-active robot to facilitate both the execution and verification of the plan, as it pertains to both the static and dynamic anatomy. The goal of this study was to assess the ability of the NAVIO RA-TKA to plan, execute and deliver an individualized approach to the soft-tissue balance of the knee, specifically in the “mid-flexion” arc of motion. Materials and Methods. Between May and September 2018, 50 patients underwent NAVIO RA-TKA. Baseline demographics were collected, including age, gender, BMI, and range of motion. The NAVIO imageless technique was used to plan the procedure, including: surface-mapping of the static anatomy; objective assessment of the dynamic, soft-tissue anatomy; and then application of a hybrid of measured-resection and
Computer assisted total knee arthroplasty helps in accurate and reproducible implant positioning, bony alignment, and soft-tissue balancing which are important for the success of the procedure. In TKR, there are two surgical techniques one is measured resection in which bony landmarks are used to guide the bone cuts and the other is gap balancing which equal collateral ligament tension in flexion and extension is done before and as a guide to final bone cuts. Both these procedures have their own advantages and disadvantages. We retrospectively collected the data of 128 consecutive patients who underwent computer-assisted primary TKA using either a
Introduction. Mid-flexion stability after total knee arthroplasty (TKA) is dependent, in large part, on implant design. Design variables include retention or sacrifice of the posterior cruciate ligament, conformity of the polyethylene tibial surface, and radius of curvature of the femoral component. In this study, we attempted to isolate the impact of femoral component design by comparing a single-radius design (SR) to a J-Curve design (JC). We selected cruciate-retaining implants to eliminate the effect of a cam-and-post mechanism. Mid-flexion performance these two designs were compared using the Lower-Quarter Y-Balance Test (YBT-LQ), as well as patient reported outcomes and measures of physical performance. The YBT-LQ is a simple functional test of unilateral lower extremity strength and balance. Reach of the contralateral limb is measured in three different directions (Figures 1–3). Our hypothesis was that the SR design would provide superior mid-flexion stability, and therefore, a greater reach distance in the YBT-LQ when compared to the JC group. Methods. Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or JC (n=30) implant. All surgeries were performed by one surgeon using a
Aim. Computer-navigated total knee arthroplasty has been shown to improve the outcome in outliers with consistent results. The aim of this study is to evaluate the clinical and radiographic outcomes of computer-navigated knee arthroplasty with respect to deformity and body mass index (BMI). Materials and Methods. Data was prospectively collected for 117 consecutive patients undergoing primary computer-navigated total knee arthroplasty using Ci Brainlab system with J&J PFC PS implants by a single surgeon utilising a tibia cut first,
The use of cementless total knee arthroplasty (TKA) components has increased during the past decade. The initial design of cementless metal-backed patellar components had shown high failure rates due to many factors. The aim of this study was to evaluate the clinical results of a second-generation cementless, metal-backed patellar component of a modern design. This was a retrospective review of 707 primary TKAs in 590 patients from a single institution, using a cementless, metal-backed patellar component with a mean follow-up of 6.9 years (2 to 12). A total of 409 TKAs were performed in 338 females and 298 TKAs in 252 males. The mean age of the patients was 63 years (34 to 87) and their mean BMI was 34.3 kg/m2 (18.8 to 64.5). The patients were chosen to undergo a cementless procedure based on age and preoperative radiological and intraoperative bone quality. Outcome was assessed using the Knee Society knee and function scores and range of motion (ROM), complications, and revisions.Aims
Methods
The April 2023 Knee Roundup360 looks at: Does bariatric surgery reduce complications after total knee arthroplasty?; Mid-flexion stability in total knee arthroplasties implanted with kinematic alignment: posterior-stabilized versus medial-stabilized implants; Inflammatory response in robotic-arm-assisted versus conventional jig-based total knee arthroplasty; Journey II bicruciate stabilized (JII-BCS) and GENESIS II total knee arthroplasty: the CAPAbility, blinded, randomized controlled trial; Lifetime risk of revision and patient factors; Platelet-rich plasma use for hip and knee osteoarthritis in the USA; Where have the knee revisions gone?; Tibial component rotation in total knee arthroplasty: CT-based study of 1,351 tibiae.
The aim of mechanical alignment in total knee arthroplasty is to align all knees into a fixed neutral position, even though not all knees are the same. As a result, mechanical alignment often alters a patient’s constitutional alignment and joint line obliquity, resulting in soft-tissue imbalance. This annotation provides an overview of how the Coronal Plane Alignment of the Knee (CPAK) classification can be used to predict imbalance with mechanical alignment, and then offers practical guidance for bone balancing, minimizing the need for soft-tissue releases. Cite this article:
Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies. In 137 robotic-assisted TKAs, extension and flexion stressed gap laxities and bone resections were measured. The primary outcome was the proportion and magnitude of medial and lateral SPI (gap differential > 2.0 mm) for KA, MA, and FA. Secondary outcomes were the proportion of knees with severe (> 4.0 mm) SPI, and resection thicknesses for each technique, with KA as reference.Aims
Methods
While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes. This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected.Aims
Methods
Robotic arm-assisted surgery offers accurate and reproducible guidance in component positioning and assessment of soft-tissue tensioning during knee arthroplasty, but the feasibility and early outcomes when using this technology for revision surgery remain unknown. The objective of this study was to compare the outcomes of robotic arm-assisted revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) versus primary robotic arm-assisted TKA at short-term follow-up. This prospective study included 16 patients undergoing robotic arm-assisted revision of UKA to TKA versus 35 matched patients receiving robotic arm-assisted primary TKA. In all study patients, the following data were recorded: operating time, polyethylene liner size, change in haemoglobin concentration (g/dl), length of inpatient stay, postoperative complications, and hip-knee-ankle (HKA) alignment. All procedures were performed using the principles of functional alignment. At most recent follow-up, range of motion (ROM), Forgotten Joint Score (FJS), and Oxford Knee Score (OKS) were collected. Mean follow-up time was 21 months (6 to 36).Aims
Methods
Patient dissatisfaction following primary total knee arthroplasty (TKA) with manual jig-based instruments has been reported to be as high as 30%. Robotic-assisted total knee arthroplasty (RA-TKA) has been increasingly used in an effort to improve patient outcomes, however there is a paucity of literature examining patient satisfaction after RA-TKA. This study aims to identify the incidence of patients who were not satisfied following RA-TKA and to determine factors associated with higher levels of dissatisfaction. This was a retrospective review of 674 patients who underwent primary TKA between October 2016 and September 2020 with a minimum two-year follow-up. A five-point Likert satisfaction score was used to place patients into two groups: Group A were those who were very dissatisfied, dissatisfied, or neutral (Likert score 1 to 3) and Group B were those who were satisfied or very satisfied (Likert score 4 to 5). Patient demographic data, as well as preoperative and postoperative patient-reported outcome measures, were compared between groups.Aims
Methods
Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))? Overall, 15 cadaveric knee joints were examined with a CR implant with three different tibial inserts (CR, UC, and MC) using an established knee joint simulator. The effects on coronal alignment, medial and lateral femoral roll back, femorotibial rotation, bony rotations (femur, tibia, and patella), and patellofemoral length ratios were determined.Aims
Methods
Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively.Aims
Methods