[Patellar tracking in knee arthroplasty].

Knee arthroplasty is a demanding procedure that, when carried out appropriately, results in significant pain relief and patient satisfaction. The success of the operation is influenced by many factors. The most important ones describe the implant design, the orientation of the components and the ligament tension.

Total Knee Arthroplasty Violates the Law of Burmester-A Biomechanical Investigation.

Background: Kinematic patterns of knees after total knee arthroplasty (TKA) are different from those of healthy knees. We hypothesised that these changes cause a relevant shift in the medial and lateral epicondyles and, consequently, the insertion sites of the collateral ligaments. Any alterations, however, violate the law of Burmester, which states a close relation between the course of the collateral and cruciate ligaments, and the articular surfaces.

Knee kinematics are variously influenced by different correction angles in high tibial osteotomy (HTO).

Purpose: Literature reveals good to excellent data concerning patient satisfaction, as well as long-term outcomes after high tibial osteotomy (HTO). These results might be influenced by changes of knee kinematics through the procedure. However, exact influence of HTO on tibiofemoral kinematics remains unknown so far.

Operative Treatment Options for Patellofemoral Arthritis: An Expert Recommendation of the AGA Patellofemoral Committee.

Background: The operative therapy of patellofemoral arthritis requires an individual approach depending on the underlying injury. However, the literature lacks recommendations for its course of action.

Purpose: To generate an expert recommendation of therapy for different patellofemoral abnormalities in patients suffering from isolated patellofemoral arthritis.

Medial Open Wedge High tibial Osteotomy (MOWHTO) does not relevantly alter patellar kinematics: a cadaveric study.

Purpose: The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown.

Methods: Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation.

A Knee Size-Independent Parameter for Malalignment of the Distal Patellofemoral Joint in Children.

Introduction: Patellar instability (PI) is a common finding in children. Current parameters describing patellofemoral joint alignment do not account for knee size. Additionally, most parameters utilize joint-crossing tibiofemoral landmarks and are prone to errors.

Trochlear dysplasia relates to medial femoral condyle hypoplasia: an MRI-based study.

Purpose: Trochlear dysplasia is one of the most important pathomorphologies predisposing to patellofemoral instability. The development of the trochlea groove is not well understood so far. We hypothesized that the underlying pathology of trochlear dysplasia is a medial hypoplasia.

Kinematic alignment in total knee arthroplasty leads to a better restoration of patellar kinematics compared to mechanic alignment.

Purpose: The influence of different implantation techniques in TKA on tibiofemoral kinematics was analysed in few investigations so far. However, the influence on patellar kinematics remain unclear. The aim of the present investigation was to compare patellar kinematics of the natural knee with those of knees after both kinematically and mechanically aligned TKAs.

Reproducibility of navigation based kinematic analysis of the knee - A cadaveric investigation.

Purpose: Several navigation-based kinematic studies of the knee have been published recently, but little information is available about reproducibility and reliability of the acquired data. The aim of the present study first is to determine reproducibility and reliability of kinematical measurements of healthy knees and knees after TKA (total knee arthroplasty) with regards to rotational and translational measurement parameters. Second the mathematical background, applicability, and limitations of investigating navigation-based kinematics should be compiled.

Kinematic component alignment in total knee arthroplasty leads to better restoration of natural tibiofemoral kinematics compared to mechanic alignment.

Purpose: Kinematically aligned total knee arthroplasty is associated with superior pain relief, increased flexion and a more normal feeling knee. It was hypothesized that due to restoring the knee's natural anatomy, kinematically aligned knees show more physiological tibiofemoral kinematics than mechanically aligned knees.

Methods: Investigations were performed in nine healthy cadaveric knees of whole bodies fixed by the Thiel method.

Multicenter cohort-study of 15326 cases analyzing patient satisfaction and perioperative pain management: general, regional and combination anesthesia in knee arthroplasty.

Numbers of knee replacement surgeries have been rising over the past years. After having ameliorated operation techniques and material, pain management and anesthetic methods have come into focus. All 15326 patients included had undergone primary knee arthroplasty within this multicenter cohort-study, conducted in 46 orthopedic departments.

Rotation of intramedullary alignment rods affects distal femoral cutting plane in total knee arthroplasty.

Purpose: Intramedullary rods are widely used to align the distal femoral cut in total knee arthroplasty. We hypothesised that both coronal (varus/valgus) and sagittal (extension/flexion) cutting plane are affected by rotational changes of intramedullary femoral alignment guides.

Methods: Distal femoral cuts using intramedullary alignment rods were simulated by means of a computer-aided engineering software in 4°, 6°, 8°, 10°, and 12° of valgus in relation to the femoral anatomical axis and 4° extension, neutral, as well as 4°, 8°, and 12° of flexion in relation to the femoral mechanical axis.

Postoperative pain and patient satisfaction are not influenced by daytime and duration of knee and hip arthroplasty: a prospective cohort study.

Purpose: The number of total hip and knee arthroplasties (THA and TKA) is steadily increasing. Many factors that influence pain have been reported, but little is known about the correlation between the time of day and the duration of surgery and postoperative pain. On one hand, surgical interventions are performed faster due to economic pressure; on the other hand, obtaining sound surgical skills and a thorough education are most important for young surgeons, particularly at university hospitals.

The influence of varus and valgus deviation on patellar kinematics in healthy knees: An exploratory cadaver study.

Background: Patellofemoral instability may lead to osteoarthritis, anterior knee pain, and patellar luxation. The purpose of this study was to conduct an exploratory investigation into the difference of patellar kinematics of healthy knees during extension/flexion cycles in neutral, varus and valgus alignment.

Methods: The three-dimensional patellar kinematics of 10 lower extremities of whole body cadavers were examined during passive motion, in neutral position, and under valgus and varus stress.

Stability of capsule closure and postoperative anterior knee pain after medial parapatellar approach in TKA.

Purpose: Anterior knee pain after total knee arthroplasty (TKA) remains a widely discussed postoperative complication. In contrast to sports traumatology, the role of the dissected medial patellofemoral ligament (MPFL) using a medial parapatellar approach in TKA has not been discussed so far. In the present study, it was hypothesized that the attempted repair of the MPFL in TKA by simple closure of the joint capsule may not be successful in some cases, causing anterior knee pain.

Presence of rotational errors in long leg radiographs after total knee arthroplasty and impact on measured lower limb and component alignment.

Purpose: Rotation of the lower limb in weight bearing long leg radiographs has a great impact on measured component and lower limb alignment parameters. We asked which rotational errors of long leg radiographs are present in a high volume centre and which radiological and clinical consequences arise regarding measured coronal component and lower limb alignment after total knee arthroplasty.

Methods: In 100 long leg radiographs coronal femoral and tibial component alignment and hip knee ankle angle (HKA) were measured.

Are We Subluxating Knees in Total Knee Arthroplasty? A Cadaveric Investigation.

Background: In comparison to coronal, sagittal, and rotational alignment, translational alignment parameters have been widely neglected in total knee arthroplasty (TKA) so far. As there is a certain variable range of possible component placement in mediolateral, ventrodorsal, and proximodistal direction, we hypothesized that relative positions between the femoral and tibial bones are changed after TKA, resulting in a subluxation of knees.

Methods: In 10 knees of Thiel-embalmed whole body cadavers, the relative position between the femur and the tibia during passive flexion was measured before and after TKA by means of a navigational device.

Lower Limb Anatomy and Alignment Affect Natural Tibiofemoral Knee Kinematics: A Cadaveric Investigation.

Background: During flexion, normal knee kinematics consists of a complex combination of rolling, gliding, and rotation between femur and tibia. Although in vivo studies have shown wide interindividual variability, we hypothesized that knee kinematics is either correlated to the anatomy of the individual knee joint or to the anatomic alignment of the entire lower extremity.

Methods: The passive kinematics of 10 healthy knees was assessed in whole cadavers using a commercial computed tomography-free navigation device with intracortical pins.

Decreased femoral periprosthetic bone mineral density: a comparative study using DXA in patients after cementless total hip arthroplasty with osteonecrosis of the femoral head versus primary osteoarthritis.

Introduction: Trabecular properties in osteonecrosis of the femoral head (ONFH) are altered for bone volume and structure in the femoral head and proximal femoral canal. We analysed the periprosthetic bone mineral density (BMD) as a correlate to bony ingrowth in patients with ONFH who received a cementless THA.

Materials And Methods: We performed a matched-pair analysis of 100 patients with ONFH (n = 50) and primary osteoarthritis (n = 50) who received the same, unilateral cementless THA.

Changes in sagittal component alignment alters patellar kinematics in TKA: an in vitro study.

Purpose: Patellar maltracking due to incorrect component alignment is considered as a main reason for anterior knee pain after total knee arthroplasty (TKA). In contrast to coronal and axial component placement, the influence of sagittal component alignment on patellar kinematics has not been investigated so far.

Methods: In ten lower cadaveric limbs, TKAs were implanted using a commercial computer navigation system.