Total blood loss and early clinical outcomes under different tranexamic acid regimes in total knee arthroplasty.

BACKGROUND: Many different regimes of intravenous and local tranexamic acid (TXA) reduce total blood loss (TBL) in patients undergoing total knee arthroplasty (TKA). However, the most effective TXA regime in reducing blood loss might not be most beneficial for the patient. The aim of the present study was to investigate the effect of commonly used TXA regimes on blood loss and on early clinical outcomes. METHODS: We performed this monocentric retrospective study in patients undergoing primary TKA. Primary outcome was the estimated TBL. Secondary outcomes were the rates of adverse events (AE) as well as the range of motion (ROM), mobility and pain intensity during the first three physiotherapy sessions (PTS). RESULTS: We analysed the data of 1250 TKAs. 5 different TXA regimes were applied. TBL (mean ± SE) was 953 ± 64 ml (2xiv), 999 ± 19 ml (2xiv + 1xlocal), 1075 ± 19 ml (1xiv + 1xlocal), 1191 ± 39 ml (1xlocal) and 1241 ± 48 ml (1xiv) (p < 0.01). In the linear regression model for TBL a lower number of TXA applications was a predictor for increased blood loss (p < 0.01). AE rates were lowest under 2xiv (0%) and 2xiv + 1xlocal (4.8%). Highest mobility and lowest pain intensity were observed under 1x iv and 2x iv. The largest portions of fully mobile patients on day three were observed under 1xiv (100%), 2xiv (100%) and 2xiv + 1local TXA (86.9%). CONCLUSION: Our results suggest that multiple applications of TXA are more effective in decreasing blood loss than excessive dosing of TXA. Interestingly, local use of TXA might be associated with higher pain intensity and decreased mobility on the first days after surgery.

Handmade spacers for two-stage exchange at the hip.

OBJECTIVE: Two-stage exchange with implantation of a temporary spacer is the gold standard treatment for chronic periprosthetic joint infection of the hip. This article describes a simple and safe technique for handmade spacers at the hip. INDICATION: Periprosthetic joint infection of the hip. Septic arthritis of the native joint. CONTRAINDICATIONS: Known allergy against components of polymethylmethacrylate bone cements. Inadequate compliance for two-stage exchange. Patient unfit to undergo two-stage exchange. Bony defect situation at the acetabulum impeding stable reduction of the spacer. Bone loss at the femur jeopardizing stable fixation of the stem. Soft tissue damage with need for plastic temporary vacuum-assisted wound closure (VAC) therapy. SURGICAL TECHNIQUE: Tailoring bone cement with antibiotics. Preparation of a metal endoskeleton. Molding of spacer stem and head by hand. Customizing spacer off-sets to bony anatomy and soft tissue tension. Implantation assuring rotational stability at the femur with a bone cement collar. Confirmation of correct position by intraoperative radiography. POSTOPERATIVE MANAGEMENT: Restricted weight-bearing. Range of motion as possible. Reimplantation after successful treatment of infection.

Handmade articulating spacer for two-stage exchange at the knee.

OBJECTIVE: Two-stage exchange with implantation of a temporary spacer is considered gold standard treatment for chronic periprosthetic joint infection of the knee. This article describes a simple and safe technique for handmade articulating spacers at the knee. INDICATION: Chronic or relapsing periprosthetic joint infection of the knee. RELATIVE CONTRAINDICATIONS: Known allergy against components of polymethylmethacrylate (PMMA) bone cements or admixed antibiotics. Inadequate compliance for two-stage exchange. Patient not able to undergo two-stage exchange. Bony defect situation at the tibia or femur leading to collateral ligament insufficiency. Soft tissue damage with need for plastic temporary vacuum-assisted wound closure (VAC) therapy. SURGICAL TECHNIQUE: Removal of the prosthesis, thorough debridement of necrotic and granulation tissue, tailoring bone cement with antibiotics. Preparation of a tibial and femoral stem. Customizing the tibial and femoral articulating spacer components to bony anatomy and soft tissue tension. Confirmation of correct position by intraoperative radiography. POSTOPERATIVE MANAGEMENT: Protection of the spacer with an external brace. Restricted weight-bearing. Passive range of motion as possible. Intravenous-followed by oral antibiotics. Reimplantation after successful treatment of infection.

Conversion total hip arthroplasty following proximal femur fracture: A retrospective analysis.

BACKGROUND: The incidence of conversion total hip arthroplasty (cTHA) following reduction and fixation for proximal femur fractures will increase in parallel to the aging population worldwide. OBJECTIVE: The goal of this study is to report the frequency of bacterial detection and the outcome of cTHA at the authors' institution and to analyze preoperative factors that correlate with higher rates of bacterial growth and septic revision. METHODS: 48 patients who had been converted to THA after osteosynthesis of a proximal femur fracture either by a one- or two-stage procedure were included. Septic failure rate and the frequency of bacterial detection at the time of fixation device removal were calculated. The influence of different preoperative factors was examined by the odds ratio. A receiver operating characteristic curve of c-reactive protein (CRP) for detection of bacterial growth at the time of fixation device removal was calculated. RESULTS: 18.8% patients showed positive bacterial cultures, with Staph. epidermidis being the most frequent pathogen (33.3%). Septic failure after cTHA occurred in 4.2%. Fixation with cephalomedullary nails and complications with the internal fixation showed higher odds for bacterial growth at time of cTHA. CRP for predicting bacterial growth had an area under the curve of 0.661. Implant survival was worse when temporary spacers were used. CONCLUSION: Bacterial detection rate at the time of cTHA is high, whereas septic failure rates are low. Isolated evaluation of inflammatory blood markers without other diagnostic modalities for infection is not decisive and does not justify a two-stage approach with implantation of a temporary spacer.

Revision of unicompartmental knee arthroplasty using the in situ referencing technique.

OBJECTIVE: Revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) with the in situ referencing technique aiming to preserve as much ligament function and epi-metaphyseal bone stock as possible. INDICATIONS: Aseptic loosening, progression of osteoarthritis, periprosthetic fracture, periprosthetic infection, arthrofibrosis, polyethylene wear, malalignment, instability, femoro-tibial impingement. CONTRAINDICATIONS: Unexplained pain, localized or systemic active infection (anywhere). SURGICAL TECHNIQUE: Referencing for the tibia and the femur cuts is performed prior to implant removal. The tibial cutting jig and the initial tibial resection level is set in a way that the sawblade just fits under the tibial implant. In case too much bone needs to be removed to achieve flush implant sitting on both the medial and lateral tibia, a step cut needs to be performed to build up the medial defect with an augment. Prior to femoral component removal, rotational alignment is determined and intramedullary referencing for the distal femur osteotomy is performed. Level of constraint and additional tibial stem fixation is chosen according to the amount of bone resected and according to ligament stability. POSTOPERATIVE MANAGEMENT: Sterile dressings and elastic compression bandaging. No limitation of active/passive range of motion. Full weight-bearing or partial weight-bearing for 2 weeks postoperatively in the presence of bone or soft tissue defects. RESULTS: Between 2008 and 2019, 84 patients underwent revision of unicompartmental knee arthroplasty. The mean follow-up was 64 months (range 3-132 months). Implant survival after revision of UKA to TKA was 92% (95% CI = 82-97%) at 5 years of follow-up and 86% (95% CI = 69-93%) at 10 years of follow-up. The mean Oxford knee score was 20.1 (6-39, SD ± 6.5) preoperatively and 30.2 (3-48, SD ± 11.3) postoperatively. The mean visual analogue scale was 6.9 (range 1-10, SD ± 1.8) preoperatively and 3.9 (range 0-9, SD ± 2.6) postoperatively.

Mass-Encoded Reporters Reporting Proteolytic Activity from within the Extracellular Matrix.

Reporting matrix metalloproteinase (MMP) activity directly from the extracellular matrix (ECM) may provide critical insights to better characterize 2D and 3D cell culture model systems of inflammatory diseases and potentially leverage in vivo diagnosis. In this proof-of-concept study, we designed MMP-sensors, which were covalently linked onto the ECM by co-administration of the activated transglutaminase factor XIIIa (FXIIIa). Elements of the featured MMP-sensors are the D-domain of insulin-like growth factor I (IGF-I) through which co-administered FXIIIa covalently links the sensor to the ECM followed by an MMP sensitive peptide sequence and locally reporting on MMP activity, an isotopically labeled mass tag encoding for protease activity, and an affinity tag facilitating purification from fluids. All sensors come in identical pairs, other than the MMP sensitive peptide sequence, which is synthesized with l-amino acids or d-amino acids, the latter serving as internal standard. As a proof of concept for multiplexing, we successfully profiled two MMP-sensors with different MMP sensitive peptide sequences reporting MMP activity directly from an engineered 3D ECM. Future use may include covalently ECM bound diagnostic depots reporting MMP activity from inflamed tissues.