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To evaluate the usefulness of a novel MRI sequence strategy in the assessment of the periprosthetic anatomical structures after primary total knee arthroplasty. Two MR sequences were retrospectively compared for the imaging of 15 patients with implanted cruciate-retaining/fixed-bearing TKAs (DePuy, PFC Sigma): a slice encoding sequence for metal artifact correction (SEMAC) and a standard sequence. Images were acquired on a 1.5-T system. The degree of artifact reduction was assessed using several qualitative (Likert-type scale) (artifact size, distorsion, blur, image quality, periprosthetic bone, posterior cruciate ligament, lateral collateral ligament, medial collateral ligament, patella tendon, popliteal vessels) and quantitative (artifact volume, Insall–Salvati index, length of patella/tendon, prosthesis dimensions) parameters by blinded reads performed by four investigators. The SEMAC sequences were statistically compared with the standard sequence using Wilcoxon test. Additionally, the intraclass correlation coefficient (ICC) for interobserver agreement was calculated. Higher levels of blurring were found with SEMAC compared to standard sequences (p

Recent data suggest diminished post-operative quadriceps muscle strength after tourniquet application during total knee arthroplasty (TKA). The metabolic effects of the commonly utilized intraoperative tourniquet with consecutive ischaemia on the skeletal muscle cells were unknown. Ubiquitin proteasome system represents one of the main pathways involved in muscle protein breakdown contributing to muscle atrophy. Therefore, the purpose of the present study was to quantify the acute effects of the tourniquet application during TKA on the (1) concentrations of free/conjugated ubiquitin, (2) total ubiquitin-protein ligase activity, (3) proteasome-dependent and (4) proteasome-independent peptidase activities in the cells of vastus medialis. The randomized, controlled, monocentric trial included 34 patients scheduled to undergo primary TKA. Each patient was randomly assigned to the tourniquet (n = 17) or non-tourniquet group (n = 17) after receiving a written consent. Muscle biopsies of (5 × 5 × 5 mm) 125 mm3 were obtained from vastus medialis immediately after performing the surgical approach and exactly 60 min later. After preparation of the muscle tissue specimen, the concentrations of the free/conjugated ubiquitin (Ub) were measured by western blot analyses. The ubiquitination was determined as biotinylated Ub incorporated into the sum of the cytosolic proteins and expressed as total ubiquitin-protein ligase activity (tUbPL). The quantification of the proteasome-dependent and proteasome-independent peptidase activities was performed with peptidase assays. Tourniquet application did not influence the concentration of the free/conjugated Ub. There were no differences in tUbPL activities between groups and time points. Tourniquet-induced ischaemia resulted in statistically significant higher proteasome-dependent (caspase-like p = 0.0034; chymotryptic-like p = 0.0013; tryptic-like p = 0.0036) and proteasome-independent (caspase-like p = 0.03; chymotryptic-like p = 0.0001; tryptic-like p = 0.0062) peptidase activities. Tourniquet application did not affect the free/conjugated Ub as well as tUbPL significantly, emphasizing the sophisticated regulation of ubiquitination. The proteasome-dependent peptidase activities were significantly upregulated during tourniquet application, suggesting an increase in protein degradation, which in turn might explain the skeletal muscle atrophy occurring after TKA. These findings add further knowledge and should raise the awareness of surgeons about the effects of tourniquet-induced ischaemia at the molecular level. Additional high-quality research may be warranted to examine the short- and long-term clinical significance of the present data. I.

The hypothesis of our study is that a routine tibial cut during cruciate retaining TKA may result in a partial or a total removal of the PCL footprint. Therefore providing a reliable landmark is essential to estimate the probability of PCL damage with a tibial cut and to enable the surgeon to decide pre-operatively whether a cruciate retaining implant design is suitable.In a case series of 175 cruciate retaining TKA, the routinely made standing postoperative AP-view radiographs were evaluated to determine the distance between fibula head and tibial cutting plane. In a second case series knee MRI of 223 subjects were consecutively used to measure the vertical distance between tibial attachment of PCL and fibula head. The probability of partial or total PCL damage was calculated for different vertical distances between tibial cut and fibula head.The vertical distance between the tibial cut and the most proximal point of the fibula head averaged 6.1 mm ±4.8 mm. The mean vertical distance from fibula head to proximal and to distal PCL footprint revealed to be 11.4 mm ±3.7 mm and 5.4 mm ±2.9 mm, respectively. The location of the insertion was not significantly different between subgroups such as age (50 or50 years), gender and side. Based on our results 11 (7%) knees were considered at high risk of an entire PCL removal after implantation of a cruciate retaining TKA design.Currently available routine tibial preparation techniques result in partial or total posterior cruciate ligament detachment. Fibula head as a landmark aids to predict the PCL location and to estimate its disruption pre- and postoperatively on AP-view radiographs.