Quantification of vancomycin and clindamycin in human plasma and synovial fluid applying ultra-performance liquid chromatography tandem mass spectrometry

Periprosthetic joint infection is a challenging infection involving the joint prosthesis and adjacent tissue, such as synovial fluid, synovial tissue, and bone tissue. The current treatment consists of multiple surgical revisions and long-term antibiotic therapy. Treatment failure can cause poor functional outcome and reduced quality of life. Further research on the extent of antibiotic penetration into the infected tissues is of great importance. Our work aimed to develop and validate a novel ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of the commonly administered antibiotics vancomycin and clindamycin in plasma and synovial fluid. An extraction procedure consisting of zinc sulfate precipitation and dilution with eluent was used for both analytes. Chromatographic separation was performed on a Waters Acquity UPLC HSS T3 C18 column (1.8 µm, 2.1 × 100 mm), and quantification was carried out by a Waters Xevo TQ-S micro mass spectrometer. Stable isotope-labeled vancomycin-d10 served as internal standard. The method validation was performed based on the guidelines of the EMA and FDA. The calibration curves were linear over the range of 0.5–50 mg/L, with a coefficient of determination above 0.990. The validation results for precision and accuracy, specificity, matrix effects and stability were all within the acceptance range. An accurate and rapid method for the simultaneous quantification of vancomycin and clindamycin in human plasma and synovial fluid on the UPLC-MS/MS was developed, optimized and validated. The analysis has a run time of 5.2 min and 50 µL sample volume is needed. This developed method was successfully applied in eight patients with PJI and is suitable to determine the exposure of antibiotics in plasma and synovial fluid in patients during current PK/PD studies.</p

Better early functional outcome after short stem total hip arthroplasty? A prospective blinded randomised controlled multicentre trial comparing the Collum Femoris Preserving stem with a Zweymuller straight cementless stem total hip replacement for the treatment of primary osteoarthritis of the hip

Objectives Primary aim was to compare the functional results at 3 months and 2 years between short and conventional cementless stem total hip arthroplasty (THA). Secondary aim was to determine the feasibility of a double-blind implant-related trial. Design A prospective blinded randomised controlled multicentre trial in patients with osteoarthritis of the hip. All patients, research assistants, clinical assessors, investigators and data analysts were blinded to the type of prosthesis. Population: 150 patients between 18 and 70 years with osteoarthritis of the hip, 75 in the short stem and 75 in the conventional stem group. Mean age: 60 years (SD 7). Interventions: The Collum Femoris Preserving short stem versus the Zweymuller Alloclassic conventional stem. Main outcome measures The Dutch version of the Hip Disability and Osteoarthritis Outcome Score (HOOS). Secondary outcomes measures: Harris Hip Score, the Physical Component Scale of the SF12, the Timed Up and Go test, Pain and the EQ-5D. Feasibility outcomes: continued blinding, protocol adherence and follow-up success rate. Results No significant difference between the two groups. Mean HOOS total score in the short stem group increased 32.7 points from 36.6 (95% CI 32.9 to 40.2) preoperatively to 69.3 (95% CI 66.4 to 72.1) at 3 months follow-up. Mean HOOS total score in the conventional straight stem group increased 36.3 points from 37.1 (95% CI 33.9 to 40.3) preoperatively to 73.4 (95% CI 70.3 to 76.4) at 3 months follow-up. 91.2% of patients remained blinded at 2 years follow-up. Both protocol adherence and follow-up success rate were 98%. Conclusions Functional result at 3 months and 2 years after short stem THA is not superior to conventional cementless THA. There were more perioperative and postoperative complications in the short stem group. Direct comparison of two hip implants in a double-blinded randomised controlled trial is feasible. Trial registration number NTR1560

Time-Action Analysis (TAA) of the Surgical Technique Implanting the Collum Femoris Preserving (CFP) Hip Arthroplasty. TAASTIC trial Identifying pitfalls during the learning curve of surgeons participating in a subsequent randomized controlled trial (An observational study)

<p>Abstract</p> <p>Background</p> <p>Two types of methods are used to assess learning curves: outcome assessment and process assessment. Outcome measures are usually dichotomous rare events like complication rates and survival or require an extensive follow-up and are therefore often inadequate to monitor individual learning curves. Time-action analysis (TAA) is a tool to objectively determine the level of efficiency of individual steps of a surgical procedure.</p> <p>Methods/Design</p> <p>We are currently using TAA to determine the number of cases needed for surgeons to reach proficiency with a new innovative hip implant prior to initiating a multicentre RCT. By analysing the unedited video recordings of the first 20 procedures of each surgeon the number and duration of the actions needed for a surgeon to achieve his goal and the efficiency of these actions is measured. We constructed a taxonomy or list of actions which together describe the complete surgical procedure. In the taxonomy we categorised the procedure in 5 different Goal Oriented Phases (GOP):</p> <p>1. the incision phase</p> <p>2. the femoral phase</p> <p>3. the acetabulum phase</p> <p>4. the stem phase</p> <p>5. the closure pase</p> <p>Each GOP was subdivided in Goal Oriented Actions (GOA) and each GOA is subdivided in Separate Actions (SA) thereby defining all the necessary actions to complete the procedure. We grouped the SAs into GOAs since it would not be feasible to measure each SA. Using the video recordings, the duration of each GOA was recorded as well as the amount of delay. Delay consists of repetitions, waiting and additional actions. The nett GOA time is the total GOA time – delay and is a representation of the level of difficulty of each procedure. Efficiency is the percentage of nett GOA time during each procedure.</p> <p>Discussion</p> <p>This allows the construction of individual learning curves, assessment of the final skill level for each surgeon and comparison of different surgeons prior to participation in an RCT. We believe an objective and comparable assessment of skill level by process assessment can improve the value of a surgical RCT in situations where a learning curve is expected.</p

Novel metallic implantation technique for osteochondral defects of the medial talar dome: A cadaver study

BACKGROUND AND PURPOSE: A metallic inlay implant (HemiCAP) with 15 offset sizes has been developed for the treatment of localized osteochondral defects of the medial talar dome. The aim of this study was to test the following hypotheses: (1) a matching offset size is available for each talus, (2) the prosthetic device can be reproducibly implanted slightly recessed in relation to the talar cartilage level, and (3) with this implantation level, excessive contact pressures on the opposite tibial cartilage are avoided. METHODS: The prosthetic device was implanted in 11 intact fresh-frozen human cadaver ankles, aiming its surface 0.5 mm below cartilage level. The implantation level was measured at 4 margins of each implant. Intraarticular contact pressures were measured before and after implantation, with compressive forces of 1,000-2,000 N and the ankle joint in plantigrade position, 10 dorsiflexion, and 14 plantar flexion. RESULTS: There was a matching offset size available for each specimen. The mean implantation level was 0.45 (SD 0.18) mm below the cartilage surface. The defect area accounted for a median of 3% (0.02-18) of the total ankle contact pressure before implantation. This was reduced to 0.1% (0.02-13) after prosthetic implantation. INTERPRETATION: These results suggest that the implant can be applied clinically in a safe way, with appropriate offset sizes for various talar domes and without excessive pressure on the opposite cartilag

Short incisions and short stems in total hip arthroplasty

This thesis aims to evaluate the benefits and risks of two already widely implemented innovations in hip arthroplasty: minimally invasive approaches and short stems. In the first part, the amount of soft tissue damage after 5 different hip approaches is compared in a cadaver study, followed by a report of the clinical outcome of a series of patients who received a total hip arthroplasty through a minimally invasive two-incision hip approach. The second part of this thesis starts with a description of some of the challenges in hip implant related trials. The revision rates, as reported in clinical studies, of short stem total hip arthroplasty is summarized in a systematic review. The learning curve of the surgical technique of a short stem hip arthroplasty, the Collum Femoris Preserving (CFP) stem, is analysed through video analysis and pitfalls identified through direct feedback by the surgeons. The thesis is concluded with a report of the functional outcome up to two years of a randomized controlled trial comparing the short curved CFP stem to a straight and longer Zweymuller Alloclassic hip stem