In vitro response of THP-1 derived macrophages to antimicrobially effective PHMB-coated Ti6Al4V alloy implant material with and without contamination with S. epidermidis and P. aeruginosa

Aim Periprosthetic joint infections are a devastating complication after arthroplasty, leading to rejection of the prosthesis. The prevention of septic loosening may be possible by an antimicrobial coating of the implant surface. Poly (hexamethylene) biguanide hydrochloride [PHMB] seems to be a suitable antiseptic agent for this purpose since previous studies revealed a low cytotoxicity and a long-lasting microbicidal effect of Ti6Al4V alloy coated with PHMB. To preclude an excessive activation of the immune system, possible inflammatory effects on macrophages upon contact with PHMB-coated surfaces alone and after killing of S. epidermidis and P. aeruginosa are analyzed. Methods THP-1 monocytes were differentiated to M0 macrophages by phorbol 12-myristate 13-acetate and seeded onto Ti6Al4V surfaces coated with various amounts of PHMB. Next to microscopic immunofluorescence analysis of labeled macrophages after adhesion on the coated surface, measurement of intracellular reactive oxygen species and analysis of cytokine secretion at different time points without and with previous bacterial contamination were conducted. Results No influence on morphology of macrophages and only slight increases in iROS generation were detected. The cytokine secretion pattern depends on the surface treatment procedure and the amount of adsorbed PHMB. The PHMB coating resulted in a high reduction of viable bacteria, resulting in no significant differences in cytokine secretion as reaction to coated surfaces with and without bacterial burden. Conclusion Ti6Al4V specimens after alkaline treatment followed by coating with 5–7 μg PHMB and specimens treated with H2O2 before PHMB-coating (4 μg) had the smallest influence on the macrophage phienotype and thus are considered as the surface with the best cytocompatibility to macrophages tested in the present study.

Management of bone loss in revision total knee arthroplasty: therapeutic options and results

The treatment of small to moderate size defects in revision total knee arthroplasty (rTKA) has yielded good results with various techniques (cement and screws, small metal augments, impaction bone grafting and modular stems). However, the treatment of severe defects remains problematic. Severe defects have typically been treated with large allograft and metaphyseal sleeves. The use of structural allograft has decreased in recent years due to increased long-term failure rates and the introduction of highly porous metal augments (cones and sleeves). A systematic review of level IV evidence studies on the outcomes of rTKA metaphyseal sleeves found a 4% rate of septic revision, and a rate of septic loosening of the sleeves of 0.35%. Aseptic re-revision was required in 3% of the cases. The rate of aseptic loosening of the sleeves was 0.7%, and the rate of intraoperative fracture was 3.1%. The mean follow-up was 3.7 years. Another systematic review of tantalum cones and sleeves found a reoperation rate of 9.7% and a 0.8% rate of aseptic loosening per sleeve. For cones, the reoperation rate was 18.7%, and the rate of aseptic loosening per cone was 1.7%. The reported survival of metal sleeves was 99.1% at three years, 98.7% at five years and 97.8% at 10 years. The reported survival free of cone revision for aseptic loosening was 100%, and survival free of any cone revision was 98%. Survival free of any revision or reoperation was 90% and 83%, respectively. Cite this article: EFORT Open Rev 2021;6:1073-1086. DOI: 10.1302/2058-5241.6.210007

Poor outcomes of revision total knee arthroplasty in patients with septic loosening compared to patients with aseptic loosening

Background The purpose of this study was to compare the functional outcomes, activity levels, mortalities, implant survival rates, and complications in revision total knee arthroplasty (TKA) of patients with septic loosening with those in patients with aseptic loosening over a minimum 10-year follow-up period. Methods A cohort of 78 patients (36 septic loosening and 42 aseptic loosening) was selected between January 2008 and December 2009. The functional outcomes, activity levels, mortalities, implant survival rates, and complications of revision TKA in patients with septic and aseptic loosening were compared. Results The mean Knee Society knee scores in the septic and aseptic groups improved from 36.7 and 37.4 preoperatively to 65.3 and 76.8 points at the final follow-up, respectively (p < 0.05). Outdoor ambulatory patients at the final follow-up included 20 of 29 (69.0%) patients in the septic group and 35 of 39 (89.7%) patients in the aseptic group (p < 0.05). The cumulative mortality rates in the septic and aseptic groups were 19.4% (7/36) and 7.1% (3/42) (p = 0.102) at final follow-up, respectively. Kaplan–Meier survivorship analysis with re-revision of either component as an endpoint in the septic and aseptic groups estimated 86.5% and 95.5% chance of survival for 10 years, respectively. Conclusions Revision TKA in patients with septic loosening had worse functional outcomes and higher mortality over a minimum 10-year follow-up period compared with that in patients with aseptic loosening. Level of evidence IV.

POLARIZATION TOMOGRAPHY METHODS TO DIFFERENTIATE ASEPTIC AND SEPTIC LOOSENING AFTER TOTAL HIP REPLACEMENT

This article contains: • Structural-logical scheme and analytical description of the differential diagnosis for aseptic and septic loosening after total hip replacement using the methods of differential Mueller-matrix mapping of circular birefringence (CB) distributions of polycrystalline synovial fluid (SF) films. • Statistical analysis of the distributions of CB in polycrystalline SF films obtained from patients in the control group and groups with different hip joint pathology. • Results of establishing the strength of the differential Mueller-matrix mapping method of the distributions of CB polycrystalline films of SF by means of information analysis based on sensitivity determination, specificity and accuracy of the polarization tomography technique. • Clinical example of using polarization tomography methods to differentiate aseptic and septic cup loosening after total hip replacement

Straight stem and threaded cup in patients under 60 years of age: 28.8–30.2 years of follow-up

Purpose The aim of this retrospective observational study of one cohort was to evaluate the long-term outcome in patients younger than 60 years after total hip arthroplasty using a straight uncemented stem and an uncemented threaded cup. Methods Between 1986 and 1987, 75 hips of 75 patients (mean age, 53.35 ± 6.17 years) were consecutively implanted with an Alloclassic Zweymüller/Alloclassic SL stem and an Alloclassic CSF cup. Forty-four patients had died over the last 30 years. The remaining 31 patients (mean age, 82.9 ± 6.4 years) were reinvited for follow-up examinations. Clinical and radiographic evaluations were carried out. Results At a mean follow-up of 29.5 (28.8–30.2), 4 patients (5.3%) were lost to follow-up. For the endpoint aseptic loosening (defined as the removal of stem or the cup for 2 cases), the overall survival rate is 97.3%. For the endpoint revision for any reason (22 patients), the survival rate is 70.6%. Eleven patients needed an exchange of head and liner, caused by wear. The average time from implantation until change of head and liner was 21.44 years (SD 5.92). Other reasons for revision surgery were septic loosening (3 cases), aseptic loosening of stem and cup (1 case), aseptic loosening of stem (1 case), periprosthetic calcification (2 cases), implant fracture (1 case), periprosthetic fracture (1 case), intraoperative fissure of stem (1 case), and total wear of liner including cup (1 case). Conclusion The combination of a straight stem (Alloclassic) and a screw cup (CSF) shows excellent results in young patients under the age of 60 at ultra-long-term follow-up at 30 years. Revisions due to wear of the polyethylene liner are more likely than in the older patients.

Straight stem and threaded cup in patients under 60 years of age. 28.8-30.2 years of follow-up

Purpose: The aim of this retrospective observational study of one cohort was to evaluate the long-term outcome in patients younger than 60 years after total hip arthroplasty using a straight uncemented stem and an uncemented threaded cup.Methods:Between 1986 and 1987, 75 hips of 75 patients (mean age: 53.35±6.17 years) were consecutively implanted with an Alloclassic Zweymüller/Alloclassic SL stem and an Alloclassic CSF cup. 44 patients had died over the last 30 years. The remaining 31 patients (mean age: 82.9±6.4years) were reinvited for follow-up examinations. Clinical and radiographic evaluations were carried out.Results: At a mean follow-up of 29.5 (28.8-30.2), 4 patients (5.3%) were lost to follow up.For the endpoint aseptic loosening (defined as the removal of stem or the cup for 2 cases), the overall survival rate is 97.3%. For the endpoint revision for any reason (22 patients), the survival rate is 70.6%. Eleven patients needed an exchange of head and liner, caused by wear. The average time from implantation until change of head and liner was 21.44 years (SD 5.92). Other reasons for revison surgery were septic loosening (3 cases), aseptic loosening of stem and cup (1 case), aseptic loosening of stem (1 case), periprosthetic calcification (2 cases), implant fracture (1 case), periprosthetic fracture (1 case), intraoperative fissure of stem (1 case), total wear of liner including cup (1 case).Conclusion: The combination of a straight stem (Alloclassic) and a screw cup (CSF) shows excellent results in young patients under the age of 60 at ultra-longterm follow up at 30 years. Revisions due to wear of the polyethylene liner are more likely than in the older patients.

Cementless Tritanium Baseplate Total Knee Arthroplasty: Survivorship and Outcomes at 5-Year Minimum Follow-Up

Background Newer generation cementless total knee arthroplasty (TKA) designs have provided stronger osteointegration between the implant and bone. Despite excellent survivorship and outcomes with cemented TKAs, areas of concern within the bone–cement interface remain a concern and necessitate studies on alternative constructs. This study assesses: (1) implant survivorship; (2) clinical outcomes; and (3) complications with radiographic outcomes at a 5-year minimum follow-up of cementless highly porous titanium-coated baseplates in TKAs. Methods Part of this study has been reported. We retrospectively reviewed a prospectively collected database at a single high-volume institution between July 1, 2013 and June 30, 2014 for patients who underwent a primary TKA using cementless highly porous titanium-coated baseplate implants. Patients were evaluated clinically at postoperative follow-up visits at a minimum of 5 years. To calculate the survivorship, Kaplan–Meier analysis was performed to determine all-cause, aseptic, and septic implant survivorship at each final follow-up for all patients. Results A total of 228 TKAs were performed and followed for a minimum of 5 years (range, 5–6 years). As of the latest follow-up, one case of septic loosening of the patellar button and one case of patellar dislodgment secondary to physical manipulation were recorded and revised. Overall, the cohort displayed implant survivorship of 99.5% at 5-year minimum follow-up. Improvements were seen in both Knee Society pain and function scores and were 37 points (range, 17–60 points) and 28 points (range, 15–47 points), respectively. The mean improvement in flexion was 17.8 (range, –20 to 40 degrees) and mean improvement in extension was –5.5 (range, –30 to 5 degrees). Discussion Cementless TKAs serve as strong alternative choice to cemented TKAs. Although cemented fixation is commonly known as the gold standard, results of this study confirm the findings of previous investigations on the survivorship of cementless TKA implants. Therefore, patients who undergo primary TKA with a cementless tritanium baseplate can expect excellent clinical outcomes at a 5-year minimum follow-up.