Session 14: Hip arthroplasty

15. November
09:00 - 10:00
Lokale: Skovbrynet
Chair: Thomas Jacobsen & Signe Rosenlund

114. The association of Laminar vs. Turbulent airflow on Prosthetic Joint Infections in the Hip: A prospective nationwide study using Danish registers.
Jacob Moflag Svensson1, Anne Helms Andreasen2, Espen Jimenez Solem3, Søren Overgaard1
1. Department of Orthopedic surgery, Bispebjerg and Frederiksberg Hospital 2. Center for Clinical Research and Prevention, Frederiksberg Hospital 3. Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital

Background: Prosthetic joint infection is a rare but feared complication of total hip arthroplasty, causing severe suffering for the patient with increased morbidity and mortality, and increased costs for the healthcare system. Cleanliness in the operating room is known to affect the risk of infection. To achieve a cleaner environment, laminar airflow ventilation was introduced, which reduces the number of bacteria in the air during surgery. Despite this, most previous studies comparing laminar airflow with conventional, turbulent airflow show no difference between the two.
Aim: To evaluate the association between theatres equipped with laminar airflow (LAF) ventilation or turbulent airflow (TAF) ventilation and prosthetic joint infection (PJI) in primary total hip arthroplasty (THA).
Materials and Methods: 119,899 primary THAs with at least 365 days follow- up were registered in the Danish hip arthroplasty register (DHR) between 2010 and 2020. 27,747 THAs were excluded from the study, due to other diagnoses than osteoarthritis or errors in registration. Data from DHR and the Danish microbiology register were linked using the patients’ unique personal number. The primary outcome was revision due to PJI within 365 days after surgery. This was defined as the diagnosis PJI registered in DHR after revision surgery or 2 or more positive identical bacterial cultures in perioperative biopsies.
Results: Out of the 92,152 patients included, 2,328 (2.53%) had revision surgery within 365 days of which 843 (0.91%) were due to PJI. After adjusting for patient related risk factors, surgery related risk factors and year of surgery there was no significant difference in the effectiveness of LAF and TAF operation rooms on the primary outcome (HR=0.99; 95% CI: 0.78- 1.26).
Interpretation / Conclusion: No association was found between theatres with LAF versus TAF on the risk of PJI in THA after 365 days. This finding contradicts previous findings that were using colony forming units as a surrogate marker for PJI, which showed an increased risk in theatres with TAF ventilation. It may support the decision to equip new hospitals with TAF ventilation systems instead of LAF.

115. Psychopharmacological treatment is a risk factor for new chronic opioid use after hip and knee arthroplasty
Simon Kornvig1,2, Henrik Kehlet3,4, Christoffer Calov Jørgensen3,4, Anders Fink-Jensen5, Poul Videbech6, Alma Becic Pedersen7,8, Claus Varnum1,2
1 Department of Orthopeadic Surgery, Lillebaelt Hospital - Vejle 2 Department of Regional Health Research, University of Southern Denmark, 3 Section for Surgical Pathophysiology, Copenhagen University Hospital 4 Centre for Fast-track Hip and Knee Replacement, Rigshospitalet 5 Mental Health Center, Copenhagen and University of Copenhagen 6 Mental Health Center, Glostrup and University of Copenhagen 7 Department of Clinical Epidemiology, Aarhus University Hospital 8 Department of Clinical Medicine, Aarhus University

Background: Chronic opioid use is of great concern worldwide. Thus, identification of risk factors for new chronic opioid use after hip and knee arthroplasty is imperative to target preventive strategies. Even though many patients are receiving psychopharmacological treatment, the impact of these drugs on new chronic opioid use remains unclear.
Aim: The aim was to investigate whether any and different subgroups of preoperative psychopharmacological treatment are risk factors for new chronic opioid use after hip and knee arthroplasty.
Materials and Methods: This population-based cohort study included 35,037 primary hip and 31,109 primary knee arthroplasties from 2015 to 2022 identified from the Danish Hip/Knee Arthroplasty Registries. Patients with at least one redeemed opioid prescription within one year before surgery were excluded. Dispensings of psychotropics and opioids were obtained from the Danish National Prescription Registry. Preoperative psychopharmacological treatment was defined as one dispensing of psychotropics within 99 days before surgery, whereas new chronic opioid use was defined as at least two opioid dispensings within at least two quarters during the last three quarters of the first year following surgery. Relative risks of new chronic opioid use were estimated with 95% confidence intervals using binary regression and adjusted for age, sex and Charlson Comorbidity Index obtained from the Danish National Patient Register.
Results: Among hip and knee arthroplasty patients in any psychopharmacological treatment, 4.7% and 8.7% became new chronic opioid users, whereas 2.3% and 4.3% of patients not in psychopharmacological treatment became new chronic opioid users corresponding to adjusted relative risks for new chronic opioid use of 1.8 (1.6; 2.1) and 1.9 (1.7; 2.1), respectively. Sensitivity analyses of exposure subgroups, including antidepressants, serotonin reuptake inhibitors and antipsychotics, showed similar results.
Interpretation / Conclusion: Hip and knee arthroplasty patients in any psychopharmacological treatment have an almost 2-fold increased risk of new chronic opioid use. This underlines the importance of targeted prevention strategies in these patients.

116. In hip and knee arthroplasty, missing patient-reported outcome is associated with markedly increased mortality
Kornvig Simon1,2, Signe Timm1,2, Thomas Jakobsen3, Kirill Gromov4, Claus Varnum1,2
1 Department of Orthopeadic Surgery, Lillebaelt Hospital - Vejle 2 Department of Regional Health Research, University of Southern Denmark 3 Department of Orthopeadic Surgery, Aalborg University Hospital - Farsø 4 Department of Orthopeadic Surgery, Hvidovre Hospital

Background: Patient-reported outcome measures (PROMs) are essential in patient-centered arthroplasty research. However, missing data is a practical and statistical challenge that may introduce bias.
Aim: The aim was to investigate whether missing baseline PROM data was associated with 1-year follow-up scores as well as 1-year mortality and revision rate after hip and knee arthroplasty; secondarily, whether missing 1-year follow-up was associated with baseline scores.
Materials and Methods: This population-based study included 5,285 primary hip and 4,100 primary knee arthroplasties from three fast-tack centers in Denmark from 2016 to 2020 using the Danish Arthroplasty Registries. Oxford Hip/Knee Score (OHS/OKS), EQ- 5D-3/5L and EQ VAS were collected routinely before and 1 year after surgery. Scores were presented as medians and compared using Wilcoxon-Mann- Whitney test with a significance level of 5%. Unadjusted relative risks of death and revision within 1 year were estimated with 95% confidence intervals using binary regression.
Results: In hip arthroplasty, missing baseline scores were associated with lower OHS at follow-up (43 vs. 44, p<0.01) but not EQ-5D-3/5L and EQ VAS. In knee arthroplasty, missing baseline scores were associated with lower OKS at follow-up (38 vs. 40, p<0.01) and EQ VAS (80 vs. 81, p<0.05) but not EQ-5D- 3/5L. Hip and knee arthroplasty patients with missing baseline scores had relative risks of death within one year of 7.1 (3.9; 12.7) and 6.3 (3.5; 11.2), respectively. Missing baseline was not associated with revision rate the following year. Finally, missing 1-year follow-up were associated with lower baseline OHS/OKS as well as EQ-VAS and EQ- 5D-3/5L in both hip and knee arthroplasty (p<0.05).
Interpretation / Conclusion: In hip and knee arthroplasty, missing patient-reported outcome is associated with markedly increased mortality but not revision rate. This underscores the need for closer clinical follow-up of non-responders and the inherent risk of bias in studies with missing PROM data.

117. Associations between exercise-induced changes in leg extensor muscle power and physical function in patients with hip osteoarthritis. Secondary analysis from the Hip Booster Trial
Troels Kjeldsen 1, 2, 3, Ulrik Dalgas5, Søren T Skou3, 4, Frederik N Foldager1, 2, Bo M Bibby6, Inger Mechlenburg1, 2, 5
1) Department of Orthopedic Surgery, Aarhus University Hospital, Aarhus, Denmark 2) Department of Clinical Medicine, Aarhus University, Aarhus, Denmark 3) The Research and Implementation Unit PROgrez, Department of Physiotherapy and Occupational Therapy, Næstved-Slagelse-Ringsted Hospitals, Slagelse, Denmark 4) Research Unit for Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark 5) Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark 6) Department of Biostatistics, Institute of Public Health, Aarhus University, Aarhus, Denmark

Background: Clinical guidelines recommend exercise therapy as first-line treatment for hip osteoarthritis (OA) because of its effectiveness for improving physical function and reducing pain. To optimize the effect of exercise therapy on physical function, it is important to identify and understand the underlying mechanisms of that effect. LEP appears to be a stronger determinant of physical function in hip OA compared to muscle strength. However, there seems to be no longitudinal studies on the relationship between changes in LEP and changes in physical function in patients with hip OA.
Aim: To investigate associations between changes in leg extensor muscle power of the affected limb (?LEP) and changes in performance-based and patient-reported measures of physical function after 12 weeks of progressive resistance training (PRT) or neuromuscular exercise (NEMEX) in patients with hip osteoarthritis.
Materials and Methods: Secondary analyses of a randomized controlled trial. From 160 participants enrolled in the clinical trial and cluster randomized to PRT (n=82) or NEMEX (n=78), a total of 147 (92%) had complete follow-up data and were included in the analyses. Simple linear and multivariate linear regression models estimated the crude and adjusted associations between ?LEP normalized to body weight (watt/kg) and changes in a range of physical function outcome measures.
Results: Adjusted estimates [95% confidence intervals] showed associations between ?LEP (watt/kg) and changes in 30-second chair stand test (ß: 2.34 [1.33; 3.35], R2: 0.13), 9-step timed stair climb test (ß: -1.47 [-2.09; -0.85], R2: 0.38), 40- meter fast paced walking test (ß: -2.20 [-3.30; -1.11], R2: 0.09), Activities of Daily Life function (ß: 8.63 [3.16; 14.10], R2: 0.23) and Sport and Recreation function (ß: 10.57 [2.32; 18.82], R2: 0.21) subscales from the Hip disability and Osteoarthritis Outcomes Score. Group allocation to PRT did not lead to greater regression coefficients than in NEMEX.
Interpretation / Conclusion: Changes in leg extensor muscle power are consistently associated with changes in physical function across performance-based and patient- reported measures. These associations seem to be independent of allocation to PRT or NEMEX.

118. Periprosthetic joint infection diagnosed by culture-independent histopathology – introducing a new Danish standard?
Mats Bue1,2, Steen Bærentzen3, Thomas Greve4, Martin Lamm1, Thomas Falstie-Jensen1, Daan Koppens1, Johanne Gade Lilleøre2, Christen Ravn1
1. Dept. of Orthopaedic Surgery, Aarhus University Hospital 2. Dept. of Clinical Medicine, Aarhus University 3. Inst. of Pathology, Aarhus University Hospital 4. Dept. of Clinical Microbiology, Aarhus University Hospital

Background: Periprosthetic joint infection (PJI) is a common indication for total joint arthroplasty (TJA) revision. In 2021, the European Bone and Joint Infection Society (EBJIS) published the definition of PJI including positive histopathology as a confirmatory diagnostic criterion. In Denmark, histopathology, as a culture-independent modality, is not used in orthopaedic revision surgery as it is regarded as a complicated procedure with a long learning curve.
Aim: As part of a European multicentre study for prospective validation of the EBJIS PJI definition, this study aims to evaluate the use of histopathology in a cohort of consecutive TJA revisions in a Danish setting.
Materials and Methods: By 01.10.2023, the collection of 3 histopathology tissue samples (formalin-fixed) from the periprosthetic membrane was introduced in all TJA-revisions at our institution. Our clinical pathologists followed international protocols without prior training for PJI evaluation. The diagnostic threshold is =5 neutrophils in =5 high- power fields. The diagnostic protocol also incl. microbiology, synovial fluid leukocyte count and clinical findings.
Results: Inclusion after 5.5 months has resulted in 74 revisions, of which 25 cases (34%) were preoperatively suspected as PJI by the treating surgeon. All 25 cases were confirmed as PJI by the EBJIS definition: 88% with pos. microbiology, 88% with pos. histopathology and 86% with elevated synovial fluid leucocyte count. In 2 cases, pos. histopathology but no other signs of PJI were found. These cases may be seen as false positives, leading to a specificity of 96%. In 16 PJI cases with ongoing or very recent (<5 days) antibiotic treatment, 94% were pos. in histopathology but only 75% in microbiology. With continuous inclusion until 30.09.2024, we expect data from approximately 150 revisions to be available for presentation after one year.
Interpretation / Conclusion: Being the first Danish centre to introduce histopathology as part of the standard diagnostic work-up in PJI settings, we report high levels of agreement between conventional culture methods and histopathology. Histopathology appears as an applicable diagnostic tool and may particularly be valuable in patients treated with antibiotics prior to surgery.

119. Pre- and postoperative residual urine in 796 men 65 years or older, undergoing elective orthopedic surgery: A single-center, prospective cohort study
Inger Markussen Gryet1, Charlotte Graugaard-Jensen2, Asger Roer Pedersen3, Simon Toftgaard Skov4
1. Research Unit, Elective Surgery Center, Silkeborg Regional Hospital, Denmark 2. Pelvic Floor Unit, Department of urology, Aarhus University hospital, Denmark 3. University Research Clinic for Innovative Patient Pathways, Diagnostic Centre, Silkeborg Regional Hospital, Central Region Denmark, Denmark 4. Department of Orthopedic Surgery, Aalborg University Hospital, Denmark

Background: Post-void residual urine (PVR) can be a preexisting or an unknown chronic disorder, but it can also occur after surgery. A pilot-study initiated in Elective Surgery Center, Silkeborg Regional Hospital led to a collaboration with a urologist to develop a flowchart to handle men with residual urine after elective surgery. Depending on the severity, men with significant PVR volumes were either recommend follow up by the general practitioner or referred to a urology outpatient clinic for further diagnose and/or treatment.
Aim: To determine the prevalence of pre- and postoperative PVR in men >65 years undergoing common elective orthopedic surgeries (hip, knee or shoulder arthroplasty or spine surgery) and associated risk factors.
Materials and Methods: A single-center, prospective cohort study. Male patients were consecutively included during one year from April 25 2022. Data was extracted from the electronic patient files: age, lower urinary tract symptoms (LUTS), co-morbidity (e.g. diabetes or neurological disease), type of surgery and anesthesia, opioid use, pre- and postoperative PVR.
Results: 796 men were included; 316 knee-, 276 hip-, 26 shoulder arthroplasties and 178 lower back spinal surgeries. 95% (n=755) were bladder scanned preoperatively. 12% (n=89) had PVR 150-300ml, and 3% (n=23) had PVR >300ml. There was a higher risk of preoperative PVR =150ml in patients reporting LUTS, OR 1.97(1.28;3.03), having known neurological disease, OR 3.09(1.41;6.74), and the risk increased with higher age, OR 1.08 per year (1.04;1.12). Diabetes and the type of surgery was not associated with higher risk of PVR. 72% (n=569) had a postoperative bladder scan. 15% (95%CI: 12-19%) (n=70) patients without PVR preoperatively had PVR =150ml postoperatively.
Interpretation / Conclusion: Approximately 15% of the men had PVR =150ml preoperatively. Neurological disease was the most severe risk factor and secondary if reporting LUTS. As expected, the risk increased with age. Interestingly, neither diabetes nor the type of surgery was associated with a higher risk. 15% of the men without preoperative PVR had PVR after surgery. It is not possible to conclude if it is transient or chronic but further studies are ongoing.

120. Return to work after total hip arthroplasty in patients with osteoarthritis: A nationwide population-based cohort study on 9,431 patients
Peter Alsing1,2, Julie Pajaniaye1,2,3, Martin Bækgaard Stisen2,4, Søren Overgaard5,6, Erzsébet Horváth-Puhó1,4, Inger Mechlenburg2,4, Alma Becic Pedersen1,4
1. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark; 2. Department of Orthopaedic Surgery, Aarhus University Hospital, Aarhus N, Denmark; 3. Department of Dentistry and Oral University, Aarhus University; 4. Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; 5. Department of Orthopaedic Surgery and Traumatology, Copenhagen University Hospital, Bispebjerg, Denmark; 6. Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen

Background: An increasing proportion of younger patients are undergoing total hip arthroplasties (THA). Therefore, it is important for clinicians, patients, and society to understand how THA affect patients’ ability to return to work (RTW). Evidence on the role of socioeconomic status (SES) in RTW after THA is limited.
Aim: To investigate time to RTW after primary THA overall and the relation to markers of SES, including education, income, and cohabitation.
Materials and Methods: Using the Danish Hip Arthroplasty Registry, we identified 9,431 patients aged 18 to 59 years who underwent primary THA for osteoarthritis between 2008 and 2018. Information on RTW was obtained from the Danish Register for Evaluation of Marginalization and was defined as full or partial RTW. We used competing risk analysis to calculate the cumulative incidence with 95% confidence interval (CI) of RTW at 1, 6, 12, and 24 months, both overall and by markers of SES.
Results: In our cohort, 19% of patients had low education, 33% had an annual income <73,593 euro, and 21% were living alone. Overall, the median time to RTW within 24 months was 54 days (interquartile range: 77) and the incidence of RTW was 31.9% (CI: 30.9%; 32.8%) at 1 month, 86% (CI: 85%; 87%) at 6 months, 90% (CI: 89%; 91%) at 12 months and 93% (CI: 93%; 94%) at 24 months. In patients with low vs. high education, 28% vs. 39% RTW within one month, and 88% vs. 97% RTW within 24 months. In patients with low vs. high income, 26% vs. 43% RTW within one month and 85% vs. 98% RTW within 24 months. In patients living alone vs. cohabiting, 27% vs. 33% RTW within one month and 87% vs. 95% within 24 months.
Interpretation / Conclusion: Overall, 86% of patients who underwent THA RTW within 6 months, increasing to 93% within 24 months. Patients with low education, low income, and living alone had experienced delayed RTW or did not RTW within 24 months. These results highlight the importance of considering SES markers in clinical decision-making, as they can have health and financial implications.