[The third-generation modern cementing technique in hip and knee arthroplasty]. / Moderne Zementiertechnik der dritten Generation in der Knie- und Hüftendoprothetik.

BACKGROUND: Implant loosening is the most common reason for revision surgery. OBJECTIVES: Contribution of modern cementing technique to the long-term stability of an implant. METHODS: Evaluation of the available evidence on modern cementing technique. RESULTS: Modern cementing technique in hip arthroplasty is considered established and leads to better cementing results. In knee arthroplasty, there are also specific recommendations, including intensive cleaning of the bone bed, mixing of bone cement under vacuum and application of bone cement to the implant and the bone. CONCLUSIONS: The use of modern cementing technique in hip and knee arthroplasty facilitates cementing, increases safety, and minimizes the risk of mechanical loosening.

[Physiological reactions in the interface between cementless implants and bone]. / Physiologische Reaktionen im Interface zementfreier Implantate.

BACKGROUND: Surgical treatment of patients with osteoarthritis of the hip and persisting symptoms under conservative therapy has become increasingly important against the background of an aging population. OBJECTIVES: What are the physiological reactions in the interface between cementless implants and bone? METHODS: The literature is reviewed, expert opinions and animal models are analyzed and discussed. RESULTS: Surface coating of implants with hydroxyapatite or titanium can have positive effects on osteointegration. Additional local application of mediators might be beneficial for osteointegration in the future. CONCLUSION: Early peri-implant bone healing directly after implantation and late remodeling of the bone-implant interface are essential for secondary implant stability.

Effects of low-load blood flow restriction on the venous system in comparison to traditional low-load and high-load exercises.

Purpose: Blood-Flow-Restriction (BFR) training provides the ability to achieve hypertrophy effects even though only light mechanical loads are applied. However, its impact on venous pressures and function are still unknown. Therefore, the present study investigates the influence of BFR-training on intravascular venous pressure and venous function in comparison to control exercises with low or high mechanical loads. Methods: In a randomized cross-over design, ten healthy men (27.6 ± 6.4 years) underwent three trials of unilateral knee-extensor exercise with three different training protocols, low-load- (LL-RT, 30% of the individual 1-repetition-maximum, 1RM), low-load BFR- (LL-BFR-RT, 30% 1RM, 50% limb occlusion pressure, LOP) and high-load resistance exercise (HL-RT, 75% 1RM). Exercise protocols contain about four sets of knee extension exercise (Range-of-Motion: 0-0-95°), separated by 60 s of rest. Each set was performed until volitional muscle failure. For analysis of changes in intravascular venous pressures and venous function, a venous catheter was placed at the exercising leg before each trial. Whereas venous pressures were recorded throughout the exercise trials, phlebodynamometric investigations were performed before and after each trial. Furthermore, subjective pain perception during and after exercise was accessed by visual analogue scale. One-way ANOVA was used to assess mean differences between training protocols, while two-way repeated-measures ANOVA (rANOVA; time x condition) was performed to compare changes in measures over time among conditions. Data were given as means ± standard deviation (SD). Results: In comparison to the exercise trials without venous occlusion, total workload was significantly lower in the LL-BFR-RT (LL-RT: 1745 ± 604 kg vs LL-BFR-RT: 1274 ± 237 kg vs HL-RT: 1847 ± 367 kg, p = 0.004) without indicating statistical differences in venous pressures during the exercise sets (interaction: p = 0.140) or pain perception (interaction: p = 0.574). Similarly, phlebodynamometric assessment of venous function (e.g. refill-time of the venous system pre-vs. post exercise trials-LL-RT: 29.7 ± 11.0 s vs 25.5 ± 9.6 s, LL-BFR-RT: 26.6 ± 13.0 s vs 27.3 ± 13.8 s, HL-RT: 25.9 ± 10.9 s vs 23.1 ± 8.2 s) revealed no time (p = 0.156), condition effect (p = 0.802) or their interactions (p = 0.382). Conclusion: The present study is the first one describing the acute effects of LL-BFR-RT to muscle failure on venous pressures and function in comparison to a LL- and HL-RT in the lower limbs. In contrast to the existing literature, LL-BFR-RT does not elevate the venous pressures during exercise higher than a comparative exercise without BFR and does not show any adverse effects on venous function after the exercise.

Microbiological Trends and Antibiotic Susceptibility Patterns in Patients with Periprosthetic Joint Infection of the Hip or Knee over 6 Years.

We sought to analyze trends of the causative pathogens and their antibiotic susceptibility patterns in patients with periprosthetic joint infections (PJI) of the hip and knee to get better insights and improve treatment. Retrospective evaluation of all consecutive patients with microbiological detection of a causative pathogen at a tertiary endoprothetic referral center between January 2016 and December 2021 in Germany was performed. Overall, 612 different microorganisms could be detected in 493 patients (hip: n = 293; knee: n = 200). Evaluation did not show a change in the relative abundance of pathogens detected, with coagulase-negative staphylococci (n = 275; 44.9%) found frequently, followed by S. aureus (n = 86; 14.1%), Enterococcus species (n = 57; 9.3%), Streptococcus species (n = 48; 7.8%), and Gram-negative bacteria (n = 80; 13.1%). Evaluation of the antibiotic susceptibilities showed increasing rates of oxacillin-resistant coagulase-negative staphylococci (60.4%; 46.8−76.7%) and piperacillin-tazobactam-resistant Gram-negative bacteria (26.5%; 0−57.1%), although statistically not significant. Resistance of Gram-positive bacteria to vancomycin (<1%) and Gram-negative microorganisms to meropenem (1.25%) remained an exception. In summary, coagulase-negative staphylococci, as the most frequent pathogen, displayed a continuously high rate of oxacillin resistance. For the highest antimicrobial coverage in the case of an empiric therapy/unknown pathogen, vancomycin might be chosen. Level of evidence: IV.

Microbiological Profiles of Patients with Periprosthetic Joint Infection of the Hip or Knee.

Periprosthetic joint infections (PJI) are one of the most devastating consequences after total joint arthroplasty. We sought to analyze the causative pathogens of patients with PJI to get better insights and improve treatment. We performed a retrospective study of all patients with PJI of the hip and knee with microbiological detection of a causative pathogen at a tertiary endoprothetic referral center between January 2016 and March 2021. A total of 432 cases with PJI (hip: n = 250; knee: n = 182) were included. The most common causative pathogen were coagulase-negative staphylococci (n = 240; 44.2%), of which Staphylococcus epidermidis (n = 144; 26.7%) was the most frequently detected, followed by S. aureus (n = 77; 14.3%) and enterococci (n = 49; 9%). Gram-negative pathogens and fungi could be detected in 21% (n = 136) and 2.4% (n = 13) of all cases. Overall, 60% of all coagulase-negative staphylococci were oxacillin-resistant, while none of these displayed to be vancomycin-resistant. In summary, the majority of pathogens in cases of PJI could be identified as coagulase-negative staphylococci. For empirical therapy vancomycin might provide the highest antimicrobial coverage in case of an unknown pathogen.

[Use of custom-made acetabular components (CMAC) as part of a two-stage procedure in patients with severe periacetabular bone loss]. / "Custom-made acetabular components" (CMAC) beim zweizeitigen Wechsel und bei höhergradigen periazetabulären Knochendefekten.

OBJECTIVE: Implantation of custom-made acetabular components (CMAC) with load transmission onto the remaining bone stock and reconstruction of the "center of rotation" (COR) in cases of severe periacetabular bone defects. INDICATIONS: Severe periacetabular bone loss (Paprosky type IIIA/B) with or without pelvic discontinuity after septic or aseptic loosening with inadequate load capacity of the dorsal pillar and/or large supraacetabular defects. CONTRAINDICATIONS: Acute or local infections, lack of compliance, taking into account the risks and complications: missing or limited expected postoperative functional gain, multimorbid patients with potential inoperability during the first and/or second intervention. SURGICAL TECHNIQUE: Lateral transgluteal or posterolateral approach while protecting neurovascular and muscular structures. Preparation of the implant site based on preoperative planning with augmentation of bone defects as far as possible. Primarily stable anchoring with 2 angle-stable pole screws in the ilium, an optional pole screw in the pubic bone for determination of COR, and stabilization screws in the iliac wing (optionally angle-stable). Use of dual mobility cup according to the soft tissue tension and intraoperative stability. POSTOPERATIVE MANAGEMENT: For the first 6 weeks postoperative partial weight-bearing (20 kg), followed by a gradual increase of the load (10 kg per week). RESULTS: Between 2008 and 2018, 47 patients with a Paprosky type III defect underwent implantation of a monoflanged CMAC. Main complication was a periprosthetic joint infection with subsequent need for implant removal in 9 of 10 cases. Harris Hip Score improved from 21.1 to 61.5 points. X­ray imaging displayed an angle of inclination of 42.3 ± 5.3°, an anteversion of 16.8 ± 6.2°, a ∆ H of 0.5 ± 0.2 mm and a ∆ V of 17.7 ± 1.1 mm according to Roessler et al.

Synovial Complement Factors in Patients with Periprosthetic Joint Infection after Undergoing Revision Arthroplasty of the Hip or Knee Joint.

The role and diagnostic value of the synovial complement system in patients with low-grade periprosthetic joint infection (PJI) are unclear. We sought to evaluate, for the first time, the usefulness of synovial complement factors in these patients by measuring the individual synovial fluid levels of complement factors (C1q, C3b/iC3b, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, properdin, and mannose-binding lectin [MBL]). The patients (n = 74) were classified into septic (n = 28) and aseptic (n = 46). Receiver-operator characteristic curves and a multiple regression model to determine the feasibility of a combination of the tested cytokines to determine the infection status were calculated. The synovial fluid levels of C1q, C3b/C3i, C4b, C5, C5a, MBL, and properdin were significantly elevated in the PJI group. The best sensitivity and specificity was found for C1q. The multiple regression models revealed that the combination of C1q, C3b/C3i, C4b, C5, C5a, and MBL was associated with the best sensitivity (83.3%) and specificity (79.2%) for a cutoff value of 0.62 (likelihood ratio: 4.0; area under the curve: 0.853). Nevertheless, only a combined model showed acceptable results. The expression patterns of the complement factors suggested that PJI activates all three pathways of the complement system.

The Performance of a Dithiothreitol-Based Diagnostic System in Diagnosing Periprosthetic Joint Infection Compared to Sonication Fluid Cultures and Tissue Biopsies.

PURPOSE: The aim of this study was to evaluate the performance of a commercially available dithiothreitol (DTT) kit for routine use in diagnosing periprosthetic joint infections (PJIs) in comparison to conventional microbiological tissue specimens and sonication procedures in a maximal care hospital. METHODS: We applied the DTT system in 40 consecutive cases of revision arthroplasty (23 PJIs and 17 aseptic revisions), with an exchange or a removal of components. The hardware components were split between the DTT system and the conventional sonication procedure. At least three tissue biopsies and a joint fluid specimen were sent for microbiological and histopathological analysis. Data was analysed retrospectively to compare between the different methods. RESULTS: Cultures of the DTT fluid showed a sensitivity of 65% and specificity of 100%, as referenced to conventional microbiological cultures. Sonication had better sensitivity (75%) but lower specificity (85%). The categorical agreement of DTT cultures compared to sonication fluid cultures was 78% (31/40). Neither pathogen type, infection duration nor antibiotic pretreatment influenced the accuracy of the DTT, but a low pH in the DTT seemed to be associated with false-negative results. CONCLUSION: DTT was inferior in sensitivity when diagnosing PJIs compared to sonication fluid cultures and tissue biopsies. A low pH in the DTT fluid correlated with false-negative results. Nevertheless, the closed system of the DTT kit avoids contamination and false-positive results, and DTT can be an alternative where sonication is not available.

The use of negative pressure wound therapy increases failure rate in debridement and implant retention for acute prosthetic joint infection.

BACKGROUND: To date only scanty data exist regarding the effect of failed debridement, antibiotics, irrigation and retention of the prostheses (DAIR) and negative pressure wound therapy (NPWT) on the outcome of a subsequent exchange arthroplasty. OBJECTIVE: The objective of this study was to determine the success rate of a two- or multi-stage procedure after initial failed DAIR/NPWT in patients with an acute periprosthetic joint infection (PJI) and to evaluate the influence of possible risk factors for treatment failure. METHODS: Nineteen consecutive patients with a persisting PJI and ongoing NPWT after treatment of an acute PJI with DAIR of the hip or knee joint from October 2010 to June 2017 were included. All patients were treated according to a structured treatment algorithm after referral to our hospital. The endpoint was a successful reimplantation with absence of signs of infection two years after replantation ("replantation group") or treatment failure ("treatment failure group") in terms of a permanent girdlestone arthroplasty, fistula, amputation or death. A risk factor analysis was performed between the two groups. RESULTS: Explantation was performed in 15 cases, amputation in one case, and DAIR/establishment of a fistula in three cases. The treatment success rate after reimplantation in terms of "definitively free of infection" two years after surgery according to Laffer was 36.85% (seven out of 19 patients). Statistical analysis revealed the number of surgeries until wound consolidation (p= 0.007), number of detected bacterial strains (p= 0.041), a polymicrobial PJI (p= 0.041) and detection of a difficult-to-treat organism (p= 0.005) as factors associated with treatment failure. After failed DAIR/NPWT we could detect a significant higher number of different bacterial strains (p= 0.001). CONCLUSIONS: The treatment success rate after failed DAIR and NPWT with 36% is low and associated with a high treatment failure rate (permanent girdlestone arthroplasty, fistula or amputation, death). Thus, the definition of risk factors is crucial. We found that the number of revisions until wound consolidation, a polymicrobial PJI and detection of a difficult-to-treat organisms were risk factors for treatment failure. Furthermore, after failed DAIR/NPWT we could detect a significant higher number of different bacterial strains, with a possible adverse effect on a consecutive exchange.