Aims. The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA). Methods. Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and
Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model. We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition.Aims
Methods
Abstract. Introduction. Derby technique for posterolateral corner (PLC) reconstruction uses a doubled gracilis autograft to reconstruct the popliteo-fibular ligament (PFL) and a split biceps tendon transfer to reconstruct the
The anterolateral ligament (ALL) is considered as an important stabilizer of the knee joint. This ligament prevents anterolateral subluxation of the proximal tibia on the femur when the knee is flexed and internally rotated. Injury of the ALL was not investigated in patients with knee dislocation. The aim of the current research is to study the prevalence and characteristics of ALL injury in dislocated knees. A retrospective review of charts and radiological images was done for patients who underwent multiligamentous knee reconstruction surgery for knee dislocation in our institution from May 2008 to December 2016. Magnetic resonance imaging (MRI) was used to describe the ALL injury. The association of ALL injury with other variables related to the injury and the patient's background features was examined. Forty-eight patients (49 knees) were included. The mean age of the patients was 32.3 ± 10.6 years. High energy trauma was the mechanism of dislocation in 28 (57.1%) knees. Thirty-one knees (63.3%) were classified as knee dislocation (KD) type IV. Forty-five (91.8%) knees had a complete ALL injury and three (6.1%) knees had incomplete ALL injury. Forty (81.6%) knees had a complete ALL injury at the proximal fibres of the ALL, while 23 (46.9%) knees had complete distal ALL injury. None of the 46 (93.9%) knees with
Hinged elbow orthoses (HEO) are often used to allow protected motion of the unstable elbow. However, biomechanical studies have not shown HEO to improve the stability of a
Poor soft tissue balance in total knee arthroplasty (TKA) is one of the most primary causes of dissatisfaction and reduced joint longevity, which are associated with postoperative instability and early implant failure. 1. Therefore, surgical techniques, including mechanical instruments and 3-D guided navigation systems, in TKA aim to achieve optimum soft tissue balancing in the knee to improve postoperative outcome. 2. Patella-in-Place balancing (PIPB) is a novel technique which aims to restore native collateral ligament behaviour by preserving the original state without any release. Moreover, reduction of the joint laxity compensates for the loss of the visco-elastic properties of the cartilage and meniscus. Following its clinical success, we aimed to evaluate the impact of the PIPB technique on collateral ligament strain and laxity behaviour, with the hypothesis that PIPB would restore strains in the collateral ligaments. 3. . Eight fresh-frozen cadaveric legs were obtained (KU Leuven, Belgium, H019 2015-11-04) and CT images were acquired while rigid marker frames were affixed into the femur, and tibia for testing. After carefully removing the soft tissues around the knee joint, while preserving the joint capsule, ligaments, and tendons, digital extensometers (MTS, Minnesota, USA) were attached along the length of the superficial medial collateral ligament (MCL) and
The role of anconeus in elbow stability has been a long-standing debate. Anatomical and electromyographic studies have suggested a potential role as a stabilizer. However, to our knowledge, no clinical or biomechanical studies have investigated its role in improving the stability of a
Previous biomechanical studies of
Objectives. Malrotation of the femoral component can result in post-operative complications in total knee arthroplasty (TKA), including patellar maltracking. Therefore, we used computational simulation to investigate the influence of femoral malrotation on contact stresses on the polyethylene (PE) insert and on the patellar button as well as on the forces on the collateral ligaments. Materials and Methods. Validated finite element (FE) models, for internal and external malrotations from 0° to 10° with regard to the neutral position, were developed to evaluate the effect of malrotation on the femoral component in TKA. Femoral malrotation in TKA on the knee joint was simulated in walking stance-phase gait and squat loading conditions. Results. Contact stress on the medial side of the PE insert increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. There was an opposite trend in the lateral side of the PE insert case. Contact stress on the patellar button increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. In particular, contact stress on the patellar button increased by 98% with internal malrotation of 10° in the squat loading condition. The force on the medial collateral ligament (MCL) and the
Knee dislocation is a rare injury in high energy trauma, but it is even rarer in low energy injuries. We present, to our knowledge, the only case in the world literature of knee dislocation following a cricketing injury. The patient was a 46 year old recreational fast bowler who, whilst bowling, slipped on the pitch on the follow through. He sustained an anteromedial knee dislocation which was reduced under intravenous sedation. He also sustained a neuropraxia of the common peroneal nerve with grade 2 weakness of ankle and toe dorsiflexion. Magnetic Resonance Imaging (MRI) confirmed a complete rupture of anterior cruciate ligament (ACL),
Introduction. There is little information available to surgeons regarding how the lateral soft-tissue structures prevent instability in knees implanted with total knee arthroplasty (TKA). The aim of this study was to quantify the lateral soft-tissue contributions to stability following cruciate retaining (CR) TKA. Methods. Nine cadaveric knees with CR TKA implants (PFC Sigma; DePuy Synthes Joint Reconstruction) were tested in a robotic system (Fig. 1) at full extension, 30°, 60°, and 90° flexion angles. ±90 N anterior-posterior force, ±8 Nm varus-valgus and ±5 Nm internal-external torque were applied at each flexion angle. The anterolateral structures (ALS, including the iliotibial band, anterolateral ligament and anterolateral capsule), the
The function of the knee joint is to allow for locomotion and is comprised of various bodily structures including the four major ligaments; medial collateral ligament (MCL),
Aim: Accurate soft tissue balance in total knee arthroplasty (TKA) is not only technically challenging but also difficult to teach to trainees; we believe that computer navigation provides a very useful tool for objective and reproducible soft tissue balance. Methods: We studied 52 patients (31 females and 21 males) with knee osteoarthritis and recorded the change of the Medial (MCL) and
Lubricin is a proteoglycan that is a boundary lubricant in synovial joints and both a surface and collagen inter-fascicular lubricant in ligaments. The purpose of this study was to characterise the mRNA levels for lubricin in the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and
Passive knee stability is provided by the soft tissue envelope which resists abnormal motion. There is a consensus amongst orthopedic surgeons that a good outcome in TKA requires equal tension in the medial and the lateral compartment of the knee joint, as well as equal tension in the flexion and extension gap. The purpose of this study was to quantify the ligament laxity in the normal non-arthritic knee before and after standard posterior-stabilized total knee arthroplasty (PS-TKA). We hypothesized that the medial collateral ligament (MCL) and the
This in-vitro study evaluated the influence of ligament tensioning and the effectiveness of
Introduction. A prospective study was done using Kirschner (K) wires to internally fix capitellum fractures and its results were analysed. Materials/Methods. Since 1989, unstable displaced 17 capitellum fractures were anatomically reduced and internally fixed by inserting K wires in coronal plane from the capitellum into trochlea. The lateral end of wires were bent in form of a staple behind the fracture plane and anchored into the lateral humeral condyle with pre-drilled holes. Additional screws were used in 2 cases to stabilise the lateral pillar comminution. The capitellum was exposed with a limited modified lateral elbow approach between anconeus and extensor carpi ulnaris. The capsule was reflected anteriorly to expose the capitellum and trochlea. The deeper dissection was limited anterior to
Soft tissue balancing in fixed genu valgum can be challenging and may lead to instability in flexion. Current techniques involve release of the tight secondary structures initially, with the fascia lata and the lateral capsule usually addressed first, and then the posterior capsule if necessary. If ligament testing does not permit neutral alignment in extension, release of the lateral collateral ligament becomes necessary. The most common way of achieving neutral alignment is by lengthening the lateral structures through elevation of the proximal insertion of the
Ligament balancing is an integral part of total knee arthroplasty and is highly dependent on correct alignment of the knee in flexion and extension. The technique proposed begins with correct alignment of the articular surfaces of the femur both in flexion and extension so that the joint surfaces are perpendicular to the anteroposterior plane of the lower extremity. This is done separately on the femur and tibia in extension and flexion, irrespective of ligament contracture or stretching. Once alignment, sizing, and positioning of the implants are correct, the ligaments can be assessed. Only ligaments that are tight need to be released, thus minimising trauma and maximising stability of the knee. Varus Knee: Knees that are tight medially only in flexion should first have the anterior portion of the medial collateral ligament (MCL) released, leaving the posterior oblique portion intact to provide stability in flexion and extension. Knees that are tight only in extension first should have release of the posterior oblique fibres of the MCL, and release of the posterior capsule if medial contracture persists in extension. This leaves the anterior portion of the MCL intact to stabilise the knee. Major destabilisation of the knee may occur if the posterior cruciate ligament (PCL) is released after full release of the MCL, release of posterior oblique fibres of the MCL, and posterior capsule release. Valgus Knee: Knees that are tight laterally in flexion and extension first have release of the
Anatomy &
Biomechanics.