Aims

When performing revision total hip arthroplasty using diaphyseal-engaging titanium tapered stems (TTS), the recommended 3 to 4 cm of stem-cortical diaphyseal contact may not be available. In challenging cases such as these with only 2 cm of contact, can sufficient axial stability be achieved and what is the benefit of a prophylactic cable? This study sought to determine, first, whether a prophylactic cable allows for sufficient axial stability when the contact length is 2 cm, and second, if differing TTS taper angles (2° vs 3.5°) impact these results.

Aims

The worldwide COVID-19 pandemic is directly impacting the field of orthopaedic surgery and traumatology with postponed operations, changed status of planned elective surgeries and acute emergencies in patients with unknown infection status. To this point, Germany's COVID-19 infection numbers and death rate have been lower than those of many other nations.

Background

Tranexamic acid (TXA) and fibrin sealants have gained widespread use in total knee arthroplasty. They can decrease bleeding, drainage volume, hematoma formation, and incidence of blood transfusion. However, they are costly and carry a theoretical risk of infection transmission and thrombosis. This study compares the two pharmacologic interventions to preoperative autologous blood donation as well as no intervention.

Introduction

Oxidized zirconium (OxZr) is used as a ceramic surface for femoral components in total knee arthroplasty (TKA). The aim of this study was to investigate its performance by examining retrieved femoral components and their corresponding PE inserts in matched comparison with conventional chrome/cobalt/molybdenum alloy (CrCoMo).

Background: Arthroscopic femoral osteoplasties might cause prolonged operative times, restricted intraop-erative overview or insufficient localisation of surgical tools. Computer assisted techniques should improve the precision with an overall accuracy is within 1mm/1°. An automated navigated registration process matching preoperative CT data and intraoperative fluoroscopy, should allow for non-invasive registration for FAI surgery. We evaluated the general precision (I) of the CT and fluoroscopic matching process and (II) the precision of identifying the defined osseous lesions in various anatomical areas.

Material and Methods: Three cadavers (6 hip joints) utilizing a conventional navigation system were used. Before preoperative CT scans, defined osseous lesion (0.5x0.5mm) in the femoral neck, head neck junction, head region were created under fluoroscopic control. Following reference marker fixation, two fluoroscopic images (12 inch c-arm) with 30° angle differences of the hip joint were taken. Automated segmentation including CT-fluoro image fusion by the navigation system enabled a noninvasive registration process Precision of registration process was tested with a straight navigated pointer (1mm tip) trough a lateral arthroscopic portal, during virtual contact to the bone, without arthroscopic control After arthroscopic view was enabled the in vivo distance of pointer tip to bone was measured (I). In vivo real distances between inserted navigated shaver and osseous lesions was done over an anterior hip arthrotomy. Under navigated control, blinded to the situ, placement in the lesions should be done. Distances between shaver tip and osseous lesions were measured with a caliper (II).

Results: The precision for registration (I) was within 0.9mm within the femoral neck (SD 0.24mm; 0.6–1.3mm); 1.2 mm (SD 0.33mm; 0.8–2.0mm) (p> 0.05) for the head neck junction; 2.9 mm (SD 0.57mm; 1.8–3.7mm) for the femoral head (p< 0.001 respectively p< 0.001) Mean offset of the navigated shaver to the lesions (II) was 0.93 mm (SD 0.65mm; 0–2mm). Within the femoral neck a mean accuracy of 0.6mm (SD 0.59mm; 0–1.4mm), the head neck junction 0.8 mm (SD 0.78mm; 0.1–1.5mm), the femoral head 1.3 mm (SD 0.50mm; 0.6–1.7mm) was found (p> 0.05; p> 0.05; p> 0.05).

Conclusion: A combined CT-fluoroscopy matching procedure allows for a reproducible noninvasive registration process for navigated FAI surgery. Precision of the registration process itself is more accurate at the femoral neck and head-neck junction than at the femoral head area. However a navigated identification of osseous lesions was possible within 1mm deviations in all regions.

78 patients (41 male and 37 female) with a revision total knee or hip arthroplasty were enrolled in this prospective study to evaluate the role of new laboratory markers in the diagnostic of deep implant infection.

The average age at the time of surgery was 64 years. Based on intraoperative cultures, 21 patients had a septic and 57 patients had an aseptic revision total joint arthroplasty. White blood cell counts, erythrocyte sedimentation rate, C-reactive protein levels, interleukin-6, procalcito-nin and TNF-alpha were measured in preoperative blood samples. Diagnostic cut of values were determined by Receiver Operating Characteristic curve analysis.

If patients with rheumatoid arthritis and other concomitant infections are excluded the C-reactive protein (> 3.2md/dl) and interleukin 6 (> 12 pg/ml) have the highest sensitivity (0.95). Interleukin 6 is less specific than the C-reactive protein (0.87 versus 0.96). Combining C-reactive protein and interleukin identifies all patients with deep implant infection. Procalcitonin (> 0.3 ng/ml) and TNF-alpha (> 40 ng/ml) are very specific (0.98 versus 0.94)) but have a low sensitivity (0.33 versus 0.43).

The combination of C-reactive protein and interleu-kin 6 is an excellent screening tests for deep implant infection. Highly specific marker like procalcitoninn as well as preoperative joint aspiration might be useful to identify patients with true positive CRP and/or interleu-kin 6 levels.