Risk of conversion to total knee arthroplasty after surgically treated tibial plateau fractures: an observational cohort study of 439 patients.

BACKGROUND AND PURPOSE: We aimed to assess joint failure rate, i.e., subsequent conversion to TKA after surgical treatment of a tibial plateau fracture (TPF). Secondary aims were to explore the association between joint failure and fracture type, and to determine the risk of failure associated with inadequate joint surface reduction. METHODS: We included all patients ≥ 18 years of age with a surgically treated TPF, treated at Uppsala University Hospital between 2002 and 2015. All fractures were classified according to the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Traumatology Association (AO/OTA) classification. Postoperative radiographs were evaluated to determine the quality of joint surface inadequate reduction, defined as an articular step-off ≥ 2 mm. The study cohort was linked with the Swedish Arthroplasty Register (SAR) for information on subsequent total knee arthroplasty (TKA). RESULTS: 439 patients (57% women) with a mean age of 55 years (SD 17) were included. According to the AO/OTA classification, the fracture distribution was B1: 4.8%, B2: 10%, B3: 47%, C1: 12%, C2: 6.4%, and C3: 19%. 23 patients (5.2%) were converted to a TKA within 2 years of initial surgery, and 34 patients (7.7%) had been converted by the end of follow-up (16 years). AO/OTA type B3 and C3 had a 6.8 (95% confidence interval [CI] 1.6-29) times greater risk of joint failure compared with B1-2 and C1-C2 at 2 years' follow-up. Inadequate joint surface reduction led to an 8.4 (CI 3.6-20) times greater risk of conversion to TKA at 2 years' follow-up. CONCLUSION: Overall, 5.2% were converted to a TKA within 2 years. Fracture types AO/OTA B3 and C3 with a comminuted articular surface and inadequate joint surface reduction were strongly associated with joint failure.

Surgical and non-surgical treatment for fully displaced lateral clavicle fractures have similar outcomes: An observational register study of 113 patients.

INTRODUCTION: Whether displaced lateral clavicle fractures should be treated surgically remains controversial. This study aims to compare outcomes after surgical versus non-surgical treatment of such fractures. PATIENTS AND METHODS: 113 patients with lateral clavicle fractures registered in the Swedish Fracture Register (SFR) during 2018 and with complete displacement on radiography were included in this cohort study. Linkage with the National Patient Register provided information on baseline medical comorbidities and further interventions. Patient-reported outcome measures (PROM) were assessed using the European Quality of Life Scale (EQ-5D-3L), the Short Musculoskeletal Function Assessment (SMFA), and the Quick Disabilities of the Arm, Shoulder and Hand (QDASH). The primary outcome was the total number of initial and delayed surgical procedures. The secondary outcome was difference in PROM between surgically and non-surgically treated patient groups. RESULTS: At a mean follow-up of 4.4 (range 3.9-4.9) years, 35 (67 %) of the 52 patients initially treated surgically had undergone a secondary procedure, mostly for implant removal. Of the 61 initially non-surgically treated patients, 3 (5 %) underwent delayed surgical treatment due to non- or malunion. 45 (40 %) patients responded to follow-up questionnaires, but no statistically significant differences were found in any PROM between groups. CONCLUSIONS: Two thirds of surgically treated patients with displaced lateral clavicle fractures underwent two procedures. The need for delayed surgical treatment in non-surgically treated patients was low and PROM was similar in both treatment groups. Nonsurgical treatment should be considered as an option to surgery for fully displaced lateral fractures of the clavicle more often.

Reoperation-free survival after hip screws or hip arthroplasty for undisplaced femoral neck fractures in the elderly.

Aims: Our primary aim was to assess reoperation-free survival at one year after the index injury in patients aged ≥ 75 years treated with internal fixation (IF) or arthroplasty for undisplaced femoral neck fractures (uFNFs). Secondary outcomes were reoperations and mortality analyzed separately. Methods: We retrieved data on all patients aged ≥ 75 years with an uFNF registered in the Swedish Fracture Register from 2011 to 2018. The database was linked to the Swedish Arthroplasty Register and the National Patient Register to obtain information on comorbidity, mortality, and reoperations. Our primary outcome, reoperation, or death at one year was analyzed using restricted mean survival time, which gives the mean time to either event for each group separately. Results: Overall, 3,909 patients presenting with uFNFs were included. Of these patients, 3,604 were treated with IF and 305 with primary arthroplasty. There were no relevant differences in age, sex, or comorbidities between groups. In the IF group 58% received cannulated screws and 39% hook pins. In the arthroplasty group 81% were treated with hemiarthroplasty and 19% with total hip arthroplasty. At one year, 32% were dead or had been reoperated in both groups. The reoperation-free survival time over one year of follow-up was 288 days (95% confidence interval (CI) 284 to 292) in the IF group and 279 days (95% CI 264 to 295) in the arthroplasty group, with p = 0.305 for the difference. Mortality was 26% in the IF group and 31% in the arthroplasty group at one year. Reoperation rates were 7.1% in the IF group and 2.3% in the arthroplasty group. Conclusion: In older patients with a uFNF, reoperation-free survival at one year seems similar, regardless of whether IF or arthroplasty is the primary surgery. However, this comparison depends on the choice of follow-up time in that reoperations were more common after IF. In contrast, we found more early deaths after arthroplasty. Our study calls for a randomized trial comparing these two methods.

Concentrations of Cobalt, Chromium and Titanium and Immunological Changes after Primary Total Knee Arthroplasty-A Cohort Study with an 18-Year Follow-Up.

Background: Total knee arthroplasty (TKA) generates elevated metal ion concentrations, but long-term changes in the concentrations of cobalt (Co), chromium (Cr) and titanium (Ti) after primary TKA and potential subsequent immune system activation-not limited to the joint but systemically-are not known. Patients and Methods: We conducted a cohort study on 26 patients with TKA (19 women; 16 with metal-backed and 10 with all-polyethylene tibial components) 18.3 years (min. 16.7, max. 20.5) after index TKA. A total of 69% of patients additionally underwent subsequent arthroplasty of the contralateral knee or either hip after the index surgery. Blood samples were analysed by inductively coupled plasma-mass spectrometry, and leukocytes were characterised by flow cytometry. Patients were clinically assessed using the Knee Society score and by plain radiography of the knee. Results: The median metal ion concentrations were 0.7 (0.1-13.0) µg/L for Co, 0.9 (0.4-5.0) µg/L for Cr, and 1.0 (0.2-13.0) µg/L for Ti. There was no relevant difference in systemic metal ion concentrations between patients exposed to single and multiple arthroplasties. The absolute count and proportion of CD3+CD4+CD8+ T cells was inversely correlated with both Co (rho -0.55, p = 0.003) and Cr concentrations (rho -0.59, p = 0.001). Conclusions: Between the first and second decades after primary TKA, in most patients, the concentrations of Co, Cr and Ti in blood samples were below the thresholds that are considered alarming. The negative correlation of Co and Cr concentrations with a subset of lymphocytes that commonly increases during immune activation is reassuring. This represents a worst-case scenario, underscoring that the investigated metal ions remain within reasonable ranges, even after additional hardware exposure.

Static 3D Osteoblast Cell Culture on 3D Printed Titanium Scaffolds.

In vitro cell cultures are a very useful tool for the validation of biomaterial cytocompatibility, especially for bone tissue engineering scaffolds and bone implants. In this chapter, a protocol for a static three-dimensional osteoblast cell culture on titanium scaffolds and subsequent analysis of osteogenic capacity is presented. The protocol is explained for additively manufactured titanium scaffolds, but it can be extrapolated to other scaffolds with similar size and structure, while differing in composition or manufactured technology. Additionally, the protocol can be used for culture of other adherent cell types beyond osteoblast cells such as mesenchymal stem cells.

The True Dislocation Incidence following Elective Total Hip Replacement in Sweden: How Does It Relate to the Revision Rate?

(1) Background: The true dislocation incidence following THA is difficult to ascertain in population-based cohorts. In this study, we explored the cumulative dislocation incidence (CDI), the relationship between the incidence of dislocation and revision surgery, patient- and surgery-related factors in patients dislocating once or multiple times, and differences between patients being revised for dislocation or not. (2) Methods: We designed an observational longitudinal cohort study linking registers. All patients with a full dataset who underwent an elective unilateral THA between 1999 and 2014 were included. The CDI and the time from the index THA to the first dislocation or to revision were estimated using the Kaplan-Meier (KM) method, giving cumulative dislocation and revision incidences at different time points. (3) Results: 136,810 patients undergoing elective unilateral THA were available for the analysis. The 30-day CDI was estimated at 0.9% (0.9-1.0). The revision rate for dislocation throughout the study period remained much lower. A total of 51.2% (CI 49.6-52.8) suffered a further dislocation within 1 year. Only 10.9% of the patients with a dislocation within the first year postoperatively underwent a revision for dislocation. (4) Discussion: The CDI after elective THA was expectedly considerably higher than the revision incidence. Further studies investigating differences between single and multiple dislocators and the criteria by which patients are offered revision surgery following dislocation are urgently needed.

Analysis of fracture-related infections from Swedish insurance claims between 2011 and 2021.

Fracture-related infections (FRI) pose a serious complication with an incidence of 1-2%. This study aimed to analyze compensation claims submitted to The Swedish National Patient Insurance Company (LÖF) because of FRI after closed/open reduction and internal fixation (C/ORIF) in the four most common fracture sites (proximal humerus, distal radius, hip, ankle). Patients registered in the LÖF database with a suspected FRI between 2011 and 2021 were identified by matching International Classification of Diseases and procedural codes indicative of a combination of fractures to the proximal humerus, distal radius, hip and ankle, C/ORIF and infection. Medical records were reviewed for fracture sites, pathogens and complications. Data from the Swedish Fracture Register (SFR) were extracted to estimate the proportion of reported claims to the presumed number of FRI. Of 122 FRI identified in the LÖF database, 34 were after C/ORIF in the proximal humerus, 12 in the distal radius, 28 in the hip and 48 in the ankle. LÖF compensated 111 patients (91%). Median time from C/ORIF to an FRI was 3 weeks (interquartile range 2-6), and 95% of all FRI occurred within 1 year after C/ORIF. Staphylococcus aureus was the most common pathogen in patients with a distal radius, hip and ankle FRI. In contrast, Cutibacterium spp. were the most common aetiology in FRI of the proximal humerus. The total number of fractures treated with C/ORIF in the four fracture sites registered in the SFR during 2021 was 18,711. Most of the FRI patients were diagnosed within the first year after C/ORIF, and 91% of the patients received compensation. Given an expected FRI incidence of 1-2%, our estimates with extrapolated data from the SFR indicate that < 10% of affected patients applied for compensation.

Early Staphylococcal Periprosthetic Joint Infection (PJI) Treated with Debridement, Antibiotics, and Implant Retention (DAIR): Inferior Outcomes in Patients with Staphylococci Resistant to Rifampicin.

It is unknown how rifampicin resistance in staphylococci causing a periprosthetic joint infection (PJI) affects outcomes after debridement, antibiotics, and implant retention (DAIR). We thus aimed to compare the risk of relapse in DAIR-treated early PJI caused by staphylococci with or without rifampicin resistance. In total, 81 patients affected by early PJI were included, and all patients were treated surgically with DAIR. This was repeated if needed. The endpoint of relapse-free survival was estimated using the Kaplan-Meier method, and Cox regression models were fitted to assess the risk of infection relapse for patients infected with rifampicin-resistant bacteria, adjusted for age, sex, type of joint, and type of index surgery. In patients with rifampicin-resistant staphylococci, relapse was seen in 80% after one DAIR procedure and in 70% after two DAIR procedures. In patients with rifampicin-sensitive bacteria, 51% had an infection relapse after one DAIR procedure and 33% had an infection relapse after two DAIR procedures. Patients with rifampicin-resistant staphylococcal PJI thus had an increased adjusted risk of infection relapse of 1.9 (95% CI: 1.1-3.6, p = 0.04) after one DAIR procedure compared to patients with rifampicin-sensitive bacteria and a 4.1-fold (95% CI: 1.2-14.1, p = 0.03) increase in risk of infection relapse after two DAIR procedures. Staphylococcal resistance to rifampicin is associated with inferior outcomes after DAIR. These findings suggest that DAIR may not be a useful strategy in early PJI caused by rifampicin-resistant staphylococci.

Incidence of Rifampicin Resistance in Periprosthetic Joint Infection: A Single-Centre Cohort Study on 238 Patients.

BACKGROUND: Rifampicin is a pillar in the treatment of periprosthetic joint infection (PJI). However, rifampicin resistance is an increasing threat to PJI treatment. This study explores the incidence of rifampicin-resistant bacteria over time in a Swedish tertiary referral centre and the association of rifampicin resistance with infection-free survival after PJI. METHODS: The study included 238 staphylococcal PJIs treated between 2001 and 2020 for which susceptibility data for rifampicin were available. Data on causative bacteria, rifampicin resistance, treatment, and outcome were obtained. Kaplan-Meier survival analysis and Cox regression modelling estimated the infection-free cumulative survival and adjusted hazard ratios (HRs) for the risk of treatment failure. RESULTS: Rifampicin-resistant causative bacteria were identified in 40 cases (17%). The proportion of rifampicin-resistant agents decreased from 24% in 2010-2015 to 12% in 2016-2020. The 2-year infection-free survival rates were 78.6% (95% CI, 66.4-93.1%) for the rifampicin-resistant group and 90.0% (95% CI, 85.8-94.4%) for the rifampicin-sensitive group. Patients with PJI caused by rifampicin-resistant bacteria had an increased risk of treatment failure (adjusted HR, 4.2; 95% CI, 1.7-10.3). CONCLUSIONS: The incidence of PJI caused by rifampicin-resistant bacteria did not increase over the past 20 years. The risk of treatment failure in PJI caused by rifampicin-resistant bacteria is more than four times that caused by rifampicin-sensitive bacteria, highlighting the importance of limiting the development of rifampicin resistance.

Increasing risk of revision due to infection after primary total hip arthroplasty: results from the Nordic Arthroplasty Register Association.

BACKGROUND AND PURPOSE: The incidence of periprosthetic joint infection after total hip arthroplasty (THA) may be increasing. We performed time-trend analyses of risk, rates, and timing of revision due to infection after primary THAs in the Nordic countries from the period 2004-2018. PATIENTS AND METHODS: 569,463 primary THAs reported to the Nordic Arthroplasty Register Association from 2004 to 2018 were studied. Absolute risk estimates were calculated by Kaplan-Meier and cumulative incidence function methods, whereas adjusted hazard ratios (aHR) were assessed by Cox regression with the first revision due to infection after primary THA as primary endpoint. In addition, we explored changes in the time span from primary THA to revision due to infection. RESULTS: 5,653 (1.0%) primary THAs were revised due to infection during a median follow-up time of 5.4 (IQR 2.5-8.9) years after surgery. Compared with the period 2004-2008, the aHRs for revision were 1.4 (95% confidence interval [CI] 1.3-1.5) for 2009-2013, and 1.9 (CI 1.7-2.0) for 2014-2018. The absolute 5-year rates of revision due to infection were 0.7% (CI 0.7-0.7), 1.0% (CI 0.9-1.0), and 1.2% (CI 1.2-1.3) for the 3 time periods respectively. We found changes in the time span from primary THA to revision due to infection. Compared with 2004-2008, the aHR for revision within 30 days after THA was 2.5 (CI 2.1-2.9) for 2009-2013, and 3.4 (CI 3.0-3.9) for 2013-2018. The aHR for revision within 31-90 days after THA was 1.5 (CI 1.3-1.9) for 2009-2013, and 2.5 (CI 2.1-3.0) for 2013-2018, compared with 2004-2008. CONCLUSION: The risk of revision due to infection after primary THA almost doubled, both in absolute cumulative incidence and in relative risk, throughout the period 2004-2018. This increase was mainly due to an increased risk of revision within 90 days of THA. This may reflect a "true" increase (i.e., frailer patients or more use of uncemented implants) and/or an "apparent" increase (i.e., improved diagnostics, changed revision strategy, or completeness of reporting) in incidence of periprosthetic joint infection. It is not possible to disclose such changes in the present study, and this warrants further research.

Is the Robinson classification of clavicle fractures accurate enough within the setting of the Swedish Fracture Register?

INTRODUCTION: In the Swedish Fracture Register (SFR) clavicle fractures are classified according to the Robinson classification. This study aimed to evaluate the accuracy of the classification of clavicle fractures in the SFR. A secondary aim was to assess inter- and intraobserver agreement. MATERIALS AND METHODS: Clavicle fractures (n = 132) were randomly selected from the SFR and radiographs were requested for each patient from their treating departments. Not all radiographs could be acquired, and after exclusion, 115 fractures were independently classified by three expert raters blinded to patient information. The 115 fractures were classified on two occasions, 3 months apart. The raters' consensus classification was used as a gold standard that was compared to the classification registered in the SFR. The accuracy, defined as the degree of agreement between the gold standard and SFR classifications, was reported, as was the inter- and intraobserver agreement for the expert raters. RESULTS: Agreement between the classification in the SFR and the gold standard classification was fair (kappa = 0.35). Fractures with only partial displacement were often incorrectly classified as fully displaced in the SFR (n = 31 of 78 displaced fractures in the SFR). The inter- and intraobserver agreement among the expert raters was almost perfect (interobserver kappa = 0.81-0.87, intraobserver kappa = 0.84-0.94). CONCLUSIONS: The accuracy of the classification of clavicle fractures in the SFR was only fair, whereas the inter- and intraobserver agreement among the expert raters was almost perfect. Accuracy in the SFR may be improved if the classification instructions in the SFR are updated by incorporating the original classification displacement criteria, both in text and in illustrated form.

Sarcopenia prevalence and incidence in older men - a MrOs Sweden study.

INTRODUCTION: The European Working Group on Sarcopenia in Older People (EWGSOP) published a revised definition of sarcopenia in 2018. There are few incidence studies of sarcopenia following the latest definition. OBJECTIVE: To study prevalence, incidence proportion and incidence rate of sarcopenia in a simple random sample of older Swedish men using the EWGSOP2 definition. METHODS: Men aged 69-81 were invited to participate in the Osteoporotic Fractures in Men (MrOs) Sweden study. Of 2,004 included participants, 1,266 participants (mean age 75.1, SD 3.1 years) completed baseline and 5-year follow-up measurements. We assessed muscle strength by measuring grip strength and chair stands test, lean mass by dual energy X-ray absorptiometry and physical performance by gait speed at baseline and follow-up. Sarcopenia prevalence and incidence were calculated according to the EWGSOP2 definition. RESULTS: Sarcopenia prevalence increased from 5.6% at baseline to 12.0% at follow-up. During the mean 5.2-year follow-up period, 9.1% developed sarcopenia (incidence proportion), corresponding to an incidence rate of 1.8 per 100 person-years at risk while 39.4% of the participants with sarcopenia at baseline participating in follow-up reversed to no longer having confirmed sarcopenia at 5-year follow-up. CONCLUSION: The prevalence of sarcopenia defined along EWGSOP2 criteria doubled within 5 years in older men, and more than a third of the study participants with sarcopenia at baseline did not have sarcopenia at follow-up. We conclude that sarcopenia is not a static condition.

Inter-departmental variation in surgical treatment of proximal femoral fractures: A nationwide observational cohort study.

BACKGROUND AND PURPOSE: Hip fractures should be treated based on the best available evidence and cost-effectively to optimize the outcome for this large group of frail patients. This study examined nationwide variation in surgical methods used for hip fractures. METHODS: In this cohort study 46,243 patients ≥65 years with a trochanteric hip fracture (THF) or a femoral neck fracture (FNF) registered in the Swedish Fracture Register (SFR) between 1 January 2016 and 31 December 2020 were included. Fractures were classified according to the AO Foundation/Orthopaedic Trauma Association (AO/OTA) fracture classification system. The choice of surgical methods was assessed for each fracture type to compare national variation. RESULTS: 21,312 THFs and 24,072 FNFs (67% women) with a mean age of 83 years (SD 8) were surgically treated. In the treatment of two-fragment THFs (AO/OTA A1) departments ranged from using 90% short intramedullary nails to 98% sliding hip screws. Treating displaced FNFs (AO/OTA B3), the proportion of hemiarthroplasty ranged from 9 to 90%, and internal fixation between 0.6 to 21%, depending on the department. INTERPRETATION: A mature national fracture register permits the monitoring of treatment provided and thus serves as an important aid in assessing compliance with guidelines. The large inter-departmental variation in the surgical management of hip fractures in Sweden appears unwarranted based on the current evidence, indicating a need for updated national guidelines. Further research will have to clarify the impact of this variation on mortality and re-operation rates.

Nonoperative Versus Operative Treatment for Displaced Finger Metacarpal Shaft Fractures: A Prospective, Noninferiority, Randomized Controlled Trial.

UPDATE: This article was updated on January 18, 2023, because of a previous error, which was discovered after the preliminary version of the article was posted online. On page 103, in the first column of Table III, the continuous outcomes, which had been given as "Median" and "(range)", are now given as "Mean" and "(95% CI)", respectively.

Finger metacarpal fractures represent up to 31% of all hand fractures, and most can be treated nonoperatively. Whether operative treatment is superior to nonoperative treatment for oblique and/or spiral finger metacarpal shaft fractures (MSFs) is unknown. Forty-two patients with displaced oblique and/or spiral finger MSFs were randomized to either nonoperative treatment with unrestricted mobilization or operative treatment with screw fixation. The primary outcome was grip strength in the injured hand compared with the uninjured hand at the 1-year follow-up. Secondary outcomes were the Disabilities of the Arm, Shoulder and Hand score, range of motion, metacarpal shortening, complications, sick leave duration, patient satisfaction, and costs. All patients attended the 1-year follow-up. Mean grip strength relative to that in the contralateral hand was 104% (95% confidence interval [CI], 89% to 120%) in the nonoperative group and 96% (95% CI, 89% to 103%) in the operative group (p = 0.34). Mean metacarpal shortening was 5.3 mm (95% CI, 4.2 to 6.4 mm) in the nonoperative group and 2.3 mm (95% CI, 0.8 to 3.9 mm) in the operative group. In the nonoperative group, 1 minor complication was observed; in the operative group, there were 4 minor complications and 3 reoperations. The costs were estimated at 1,347 U.S. dollars (USD) for nonoperative treatment compared with 3,834 USD for operative treatment. Sick leave duration was significantly shorter in the nonoperative group (12 days [95% CI, 5 to 21 days] versus 35 days [95% CI, 20 to 54 days]) (p = 0.008). When treated with unrestricted mobilization, patients with a single displaced spiral and/or oblique finger MSF have outcomes comparable to those treated operatively, despite metacarpal shortening. Costs are substantially higher (2.8 times) and sick leave is significantly higher in the operative group. Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.

Study protocol: The DAICY trial-dual versus single-antibiotic impregnated cement in primary hemiarthroplasty for femoral neck fracture-a register-based cluster-randomized crossover-controlled trial.

BACKGROUND AND PURPOSE: Older patients with a displaced femoral neck fracture (FNF) are often treated with a cemented primary hemiarthroplasty (HA). The DAICY trial investigates whether high-dose dual-impregnated antibioticloaded cement (DIAC) including gentamicin and clindamycin can reduce the risk of periprosthetic joint infection (PJI) in comparison with low-dose single-impregnated gentamicin antibiotic-loaded cement (SIAC), in patients ≥ 60 years treated with a cemented HA for a displaced FNF. STUDY DESIGN: The trial is a national, multicenter, register-based, cluster-randomized, crossover trial. Patients ≥ 60 years with a non-pathological, displaced FNF (Type Garden 3-4/AO 31-B2 or B3) suitable for HA according to local guidelines are eligible for inclusion. Participating orthopedic departments will be randomized to start with either SIAC (control group) or DIAC treatment (intervention group) for 2 years. After 2 years, the study departments will then change to the other treatment arm for the remaining 2 years of the study. Approximately 7,000 patients will be included. The study is pragmatic in that the choice of implant brands, surgical approach and peri- and postoperative protocols follow the local routines of each participating department. All outcome variables will be retrieved after linkage of the study cohort to the following Swedish registers: the Fracture Register, the Arthroplasty Register, the National Patient Register and the Prescribed Drug Registry Outcome: The primary outcome will be periprosthetic joint infection of the index joint within 1 year after surgery. Secondary outcomes will be any reoperation on the index joint, mortality within 90 days and 1 year, resistance patterns of causative bacteria in cases of PJI, and health economics. Potential added value: This trial is designed to support or refute the efficacy of DIAC used in patients with a displaced FNF, potentially reducing PJI and resource allocation. Start of the trial and estimated duration - The DAICY trial started recruiting patients in January 2022 and will continue recruiting for approximately 4 years. Complete follow-up expected in 5 years.

Trabecular Titanium for Orthopedic Applications: Balancing Antimicrobial with Osteoconductive Properties by Varying Silver Contents.

Periprosthetic joint infection (PJI) and implant loosening are the most common complications after joint replacement surgery. Due to their increased surface area, additively manufactured porous metallic implants provide optimal osseointegration but they are also highly susceptible to bacterial colonization. Antibacterial surface coatings of porous metals that do not inhibit osseointegration are therefore highly desirable. The potential of silver coatings on arthroplasty implants to inhibit PJI has been demonstrated, but the optimal silver content and release kinetics have not yet been defined. A tight control over the silver deposition coatings can help overcome bacterial infections while reducing cytotoxicity to human cells. In this regard, porous titanium sputtered with silver and titanium nitride with increasing silver contents enabled controlling the antibacterial effect against common PJI pathogens while maintaining the metabolic activity of human primary cells. Electron beam melting additively manufactured titanium alloys, coated with increasing silver contents, were physico-chemically characterized and investigated for effects against common PJI pathogens. Silver contents from 7 at % to 18 at % of silver were effective in reducing bacterial growth and biofilm formation. Staphylococcus epidermidis was more susceptible to silver ions than Staphylococcus aureus. Importantly, all silver-coated titanium scaffolds supported primary human osteoblasts proliferation, differentiation, and mineralization up to 28 days. A slight reduction of cell metabolic activity was observed at earlier time points, but no detrimental effects were found at the end of the culture period. Silver release from the silver-coated scaffolds also had no measurable effects on primary osteoblast gene expression since similar expression of genes related to osteogenesis was observed regardless the presence of silver. The investigated silver-coated porous titanium scaffolds may thus enhance osseointegration while reducing the risk of biofilm formation by the most common clinically encountered pathogens.

Denosumab prevents acetabular bone loss around an uncemented cup: analysis of secondary outcomes in a randomized controlled trial.

BACKGROUND AND PURPOSE: Uncemented total hip arthroplasty (THA) is associated with periprosthetic bone loss. In a secondary outcome analysis from a randomized controlled trial, we studied whether denosumab can prevent loss of acetabular periprosthetic bone mineral density (pBMD) in patients who received a trabecular metal cup during uncemented THA. PATIENTS AND METHODS: 64 patients (aged 35-65 years) with unilateral osteoarthritis of the hip were randomized to 2 subcutaneous injections with denosumab or placebo, given 1-3 days post-surgery and 6 months post-surgery. Acetabular pBMD was measured in 5 regions of interest (ROIs) by dual-energy X-ray absorptiometry. Serum markers for bone metabolism were analyzed. Periprosthetic osteoblastic activity, measured as standardized uptake values (SUVs) by [18F] positron emission tomography/computed tomography, was evaluated in 32 of the 64 study patients. RESULTS: After 12 months, patients treated with denosumab had higher pBMD compared with the placebo-treated patients in 4 of 5 ROIs and in sum of ROIs 1-5. After 24 months, the effect on pBMD for patients treated with denosumab declined. Serum markers declined pronouncedly up to 12 months in patients treated with denosumab, but rebounded above baseline levels after 24 months. Patients treated with denosumab had statistically significantly lower SUVs in all ROIs, except ROI 5, after 6 months. INTERPRETATION: Based on this exploratory analysis of secondary endpoints the application of denosumab seems associated with preserved acetabular pBMD, reduced bone metabolism and attenuated periprosthetic osteoblastic activity. However, given the known rebound affects after discontinuation of denosumab treatment, these effects cannot be expected to persist. If prolonged treatment or shift to other regimes would be beneficial to reduce the risk of cup loosening is yet to be investigated.

The association of surgical approach and bearing size and type with dislocation in total hip arthroplasty for acute hip fracture.

AIMS: Patients with femoral neck fractures (FNFs) treated with total hip arthroplasty (THA) have an almost ten-fold increased risk of dislocation compared to patients undergoing elective THA. The surgical approach influences the risk of dislocation. To date, the influence of differing head sizes and dual-mobility components (DMCs) on the risk of dislocation has not been well studied. METHODS: In an observational cohort study on 8,031 FNF patients with THA between January 2005 and December 2014, Swedish Arthroplasty Register data were linked with the National Patient Register, recording the total dislocation rates at one year and revision rates at three years after surgery. The cumulative incidence of events was estimated using the Kaplan-Meier method. Cox multivariable regression models were fitted to calculate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for the risk of dislocation, revision, or mortality, stratified by surgical approach. RESULTS: The cumulative dislocation rate at one year was 8.3% (95% CI 7.3 to 9.3) for patients operated on using the posterior approach and 2.7% (95% CI 2.2 to 3.2) when using the direct lateral approach. In the posterior approach group, use of DMC was associated with reduced adjusted risk of dislocation compared to 32 mm heads (HR 0.21 (95% CI 0.07 to 0.68); p = 0.009). This risk was increased with head sizes < 32 mm (HR 1.47 (95% CI 1.10 to 1.98); p = 0.010). Neither DMC nor different head sizes influenced the risk of revision following the posterior approach. Neither articulation was associated with a statistically significantly reduced adjusted risk of dislocation in patients where the direct lateral approach was performed, although this risk was estimated to be HR 0.14 (95% CI 0.02 to 1.02; p = 0.053) after the use of DMC. DMC inserted through a direct lateral approach was associated with a reduced risk of revision for any reason versus THA with 32 mm heads (HR 0.36 (95% CI 0.13 to 0.99); p = 0.047). CONCLUSION: When using a posterior approach for THA in FNF patients, DMC reduces the risk of dislocation, while a non-significant risk reduction is seen for DMC after use of the direct lateral approach. The direct lateral approach is protective against dislocation and is also associated with a lower rate of revision at three years, compared to the posterior approach. Cite this article: Bone Joint J 2022;104-B(7):844-851.

3D-printed porous Ti6Al4V alloys with silver coating combine osteocompatibility and antimicrobial properties.

Additive manufacturing allows for the production of porous metallic implants for use in orthopaedics, providing excellent mechanical stability and osseointegration. However, the increased surface area of such porous implants also renders them susceptible to bacterial colonization. In this work, two trabecular porous Ti6Al4V alloys produced by electron beam melting were investigated for their osteocompatibility and antimicrobial effects, comparing samples with a silver-coated surface to uncoated samples. Dense grit-blasted Ti samples were used for comparison. The porous samples had pore sizes of 500-600 µm and 5 to 10 µm surface roughness, the silver-coated samples contained 7 at.% Ag, resulting in a cumulative Ag release of 3.5 ppm up to 28 days. Silver reduced the adhesion of Staphylococcus aureus to porous samples and inhibited 72 h biofilm formation by Staphylococcus epidermidis but not that of S. aureus. Primary human osteoblast adhesion, proliferation and differentiation were not impaired in the presence of silver, and expression of osteogenic genes as well as production of mineralized matrix were similar on silver-coated and uncoated samples. Our findings indicate that silver coating of porous titanium implants can achieve antimicrobial effects without compromising osteocompatibility, but higher silver contents may be needed to yield a sustained protection against fast-growing bacteria.