Session 13: DOS Best Paper

17. November
15:30 - 16:30
Lokale: Centersalen
Chair: Michael M. Petersen and Kristoffer W. Barfod

101. The association between any previous infection and prosthetic joint infection (PJI) after total hip arthroplasty (THA): A Register-based cohort study on 58,421 patients with osteoarthritis
Rajzan Joanroy¹ 6, Sophie Gubbels², Jens Kjølseth Møller³ 6, Søren Overgaard4 5, Claus Varnum¹ 6
Department of Orthopaedic Surgery, Vejle Hospital – part of Hospital Lillebaelt, Denmark¹ Division of Infectious Disease Preparedness, Statens Serum Institut, Denmark² Department of Clinical Microbiology, Vejle Hospital, part of Hospital Lillebaelt, Denmark³ Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen4 Department of Orthopedic Surgery and Traumatology, Copenhagen University Hospital, Bispebjerg, Denmark5 Institute for Regional Health Research, University of Southern Denmark6

Background: PJI after THA is a severe complication and is associated with increased risk of death. Little is known about the impact of any previous infection prior to THA on revision due to PJI or any revision.
Aim: We investigated the risk of revision due to PJI and any revision for patients with any hospitalised or community treated infection compared to patients without any infection 0-6 and 7-12 months prior to THA.
Materials and Methods: 58,421 patients with primary unilateral THAs were retrieved from 2010 to 2018 from the Danish Hip Arthroplasty Register (DHR) with 1 year follow-up. Information on infection diagnoses, reimbursed prescription antibiotic treatment, culture of intraoperative samples and cohabitation from Danish health registries (years 2009-2019) was obtained. The primary outcome was revision due to PJI with at least two positive cultures for the same microorganism. The secondary outcome was any revision. Their cumulative incidences were estimated and adjusted relative risk (RR) with 95 % confidence intervals (CI) was calculated treating death as competing risk.
Results: Previous infection 0-6 months prior to THA: The cumulative incidence of revision due to PJI was 1.9% (CI 1.7-2.1) vs. 1.5% (CI 1.4- 1.6) for patients with previous infection vs. no previous infection and 3.1% (CI 2.8-3.4) vs. 2.4% (CI 2.3-2.5) for any revision. The RR for PJI was 1.17 (CI 1.00 – 1.37) and for any revision 1.25 (CI 1.10-1.40) for patients with previous infections vs. no previous infection. Previous infection 7-12 months prior to THA: The cumulative incidence of revision due to PJI was 1.8% (CI 1.6-2.0) vs. 1.5% (CI 1.4- 1.7) for patients with previous infection vs. no previous infection and 3.1% (CI 2.8-3.4) vs. 2.4% (CI 2.3-2.6) for any revision. The RR for PJI was 1.15 (CI 0.98 – 1.35) and any revision 1.26 (CI 1.11-1.43) for patients with previous infections vs. no previous infection.
Interpretation / Conclusion: Previous infection within 1 year prior to THA increases the risk of revision due to PJI and any revision after THA. This new information may be taken into consideration when discussing indication for surgery.

102. Knee function and pain in patients treated with Persona® Total Knee System compared to patients treated with NexGen® Complete Knee Solution 2 years post-surgery – results from a blinded, multi-center Randomized Controlled Trial.
Kristian Mortensen¹, Lina Holm Ingelsrud¹, Anders Odgaard² ³, Andreas Kappel4, Claus Varnum5, Henrik M. Schrøder6, Kirill Gromov¹, Anders Troelsen¹
¹Clinical Orthopedic Research Hvidovre (CORH), Dept. of Orthopedic Surgery, Copenhagen University Hospital Hvidovre ²Dept. of Joint and Bone Surgery, Copenhagen University Hospital Rigshospitalet. ³Dept. of Orthopedic Surgery, Copenhagen University Hospital Gentofte. 4Interdisciplinary Orthopaedics, Dept. of Orthopedic Surgery, Aalborg University Hospital. 5Dept. of Orthopedic Surgery, Lillebælt Hospital - Vejle, University Hospital of Southern Denmark. 6Dept. of Orthopedic Surgery, Næstved Hospital, University Hospital of Southern Denmark.

Background: Persona is a novel Total Knee Arthroplasty (TKA) system offering additional opportunities for surgeons to fit the implant to the anatomy of the patient. Introduction of new designs calls for thorough follow up to ensure treatment quality and safety.
Aim: Purpose of our study was to compare knee function and pain and number of reoperations/revisions in patients operated with the novel TKA system to patients operated with a traditional, well-proven TKA system.
Materials and Methods: In a single-blinded RCT (NCT03073941), 311 patients (mean±SD age 68.4±8.7 years old, 61% female) were allocated to Persona or NexGen TKA. Knee function and pain was measured by Oxford Knee Score (OKS) 3 months, 1 year and 2 years post-surgery. As data was not normally distributed, differences in OKS were tested using Mann-Whitney U-test. Association between group and proportion of patients reaching the Patient Acceptable Symptom State (PASS) (OKS>=27 at 3M, OKS >=30 at 1 & 2 years), Minimal Important Change (MIC) (OKS improvement >=8 at 1 year) and number of reoperations/revisions was tested using a ?2- test.
Results: 2 years post-surgery data was available for 289 patients (93%, Persona: 142, NexGen: 147). Median OKS improved from 22 [IQR 17-27] pre- surgery to 43 [IQR 36-47] in the Persona-group and from 22 [IQR 18-26] pre-surgery to 43 [IQR 37-46] in the NexGen-group 2 years post- surgery. No difference was found between group medians pre- or 2 years post-surgery (p=.809, p=.544 respectively). Proportion of patients reaching the PASS for Persona and NexGen respectively was 84% (n=130) and 80% (n=121) at 3 months (p=.327), 89% (n=132) and 87% (n=132) at 1 year (p=.755), 92% (n=130) and 94% (n=138) 2 years post-surgery (p=.446). Proportion of patients reaching MIC for Persona and NexGen respectively was 89% (n=133) and 83% (n=126) 1 year post-surgery (p=.142). 6 patients had reoperations/revisions in the Persona group vs. 8 patients in the NexGen group (p=.576).
Interpretation / Conclusion: We found no differences between knee function and pain, number of patients reaching PASS and MIC or reoperations/revisions in patients operated with Persona or NexGen TKA. Results indicate a safe short-term performance of the Persona Total Knee System.

103. Topical Zoledronate improves fixation of cementless total knee arthroplasty by suppression of bone resorption. A randomized, double-blinded RSA study of 51 patients with 5 years follow-up
Karina Nørgaard Linde¹ ², Søren Rytter¹ ², Bente Langdahl² ³, Maiken Stilling¹ ²
Department of Orthopedics, Aarhus University Hospital, Aarhus Denmark¹ ; Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark²; Department of Endocrinology and Internal Medicine, Aarhus University Hospital³

Background: Cementless tibial implants migrate initially until osseointegration. Bisphosphonates inhibit osteoclast activity and are assumed to enhance early stable fixation and preserve periprosthetic bone.
Aim: We hypothesized that topical zoledronate (ZOL) decreases early migration and improves fixation of cementless tibial implants.
Materials and Methods: A prospective, double-blinded, randomized study including 51 patients operated with a total knee arthroplasty (TKA) using a cementless tibial implant (Regenerex). Patients were randomized to either soaking of the cut off tibia plateau for 60 sec with ZOL (0.6 ml ZOL (0.8 mg/ml) diluted in 1.4 ml NaCl (9mg/ml)) (ZOL group) or 2 ml NaCl (9mg/ml) (placebo group). We compared Maximum Total Point Motion (MTPM) and subsidence (Y-translation) using Radiostereometry Analysis (RSA) and measured biochemical markers of bone turnover in blood samples (CTX and P1NP). RSA and blood samples were obtained postoperative and at 2-, 6-, 12- and 24 weeks and at 1-, 2-, and 5-years follow-up.
Results: The ZOL group had statistically significantly less tibial implant subsidence than the placebo group at all follow-ups from 6 weeks to 5 years after surgery. At 1 year, mean tibial implant subsidence was -0.02 mm (95% CI: -0.12; 0.09) in the ZOL group and -0.34 mm (95% CI: -0.57; -0.12) in the placebo group (p=0.01). Subsidence from 1- to 2- years follow-up and from 2- to 5-years follow-up was similar between groups (p>0.14). Between 2- and 5-years, the MTPM implant migration pattern was stable in both groups. Bone resorption measured by CTX was lower at 2 weeks follow-up in the ZOL group than in the placebo group (p<0.001), bone formation (P1NP) was similar between groups throughout follow-up (p>0.05).
Interpretation / Conclusion: Compared with placebo topical administration of ZOL on the cut tibial bone surface during TKA surgery improves fixation in cementless tibial implants indicated by an early and lasting lower tibial implant subsidence, which may be explained by suppression of bone resorption after surgery. The migration pattern from 2- to 5-years follow-up was stable and similar in both groups suggesting stable long-term fixation and safety with ZOL treatment.

104. Physiotherapist-supervised exercises versus non-supervised home-based exercises after non-surgically treated proximal humerus fracture: A multicenter randomized controlled trial
Helle K. Østergaard¹, Antti P. Launonen², Marianne T. Vestermark¹, Tore Fjalestad³, Bakir O. Sumrein², Kaj V. Døssing¹, Mette H. Axelsen4, Sidsel S. Noe¹, Tone Wagle³, Kaia B. Engebretsen³, Minna K. Laitinen5, Ville M. Mattila², Inger Mechlenburg6
Department of Orthopaedic Surgery, Viborg Regional Hospital, Denmark¹: Department of Orthopaedic Surgery, Tampere University Hospital, Finland²: Department of Orthopaedic Surgery, Oslo University Hospital, Norway³: Department of Orthopaedics, Aalborg University Hospital, Denmark4: Department of Orthopaedics, Helsinki University Central Hospital and University of Helsinki, Finland5: Department of Orthopaedic Surgery, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Denmark6

Background: Proximal humerus fracture (PHF) is a common fragility fracture in older adults that can have a substantial impact on upper limb function. Although most patients with PHF can be treated non-surgically, it is unknown whether older adults benefit from supervised exercise therapy after PHF.
Aim: To investigate whether 10 weeks of physiotherapist-supervised exercises once a week was superior to10 weeks of non- supervised home-based exercises in older adults with a non-surgically treated displaced 2-part PHF.
Materials and Methods: The trial was an assessor-blinded, prospective, randomized controlled trial conducted in 3 Nordic countries. 72 non- operatively treated 2-part PHF patients age 60 years or older were randomized to either 10 weeks of physiotherapist-supervised exercises or 10 weeks of unsupervised home-based exercises. Follow-up visits took place 3 and 12 months after the fracture. The primary outcome measure was the Disability of the Arm, Shoulder and Hand (DASH) with a primary endpoint at 3 months. Secondary outcomes were the Constant-Murley Score (CS), the 15D-instrument, the Visual Analog Scale (VAS), the General Self-Efficacy scale (GSE) and the Pain Catastrophizing Scale (PCS). Non-union and patient death were counted as complications.
Results: At 3 months follow-up, the mean DASH score in the supervised group was 25.9 (SD 16.0) compared to 22.4 (18.9) in the non-supervised group. The mean between-group difference (3.5, 95% CI -5.0 to 12.5) was not clinically relevant. None of the secondary outcome measures presented any clinically relevant or statistically significant between-group differences at 3 or 12 months follow-up. One patient in the supervised group and three in the non-supervised group were diagnosed with non-union. One patient from each group died before 3 months follow-up.
Interpretation / Conclusion: This trial provides no evidence that supervised exercises are superior to non-supervised home-based exercises in improving functional outcome or quality of life in older patients with a non-surgically treated 2-part PHF. Our results suggest that most older adults with a non- surgically treated 2-part PHF can perform exercises without supervision from a physiotherapist.

105. Randomized Controlled Trial of Instrumented Versus Uninstrumented Posterolateral Fusion for Lumbar Spondylolisthesis
Andreas Kiilerich Andresen, Leah Carreon, Mikkel Ø. Andersen
Center for Spine Surgery and Research, Lillebaelt Hospital, Middelfart, Denmark ; Institute of Regional Health Research, University of Southern Denmark, Winsløwparken 19, 3, DK-5000, Odense C, Denmark.

Background: Although instrumented posterolateral fusion is the standard of care in North America, in Scandinavia uninstrumented fusion is often the treatment of choice for degenerative spondylolisthesis in patients aged above 60 years. The main argument for this procedure is to minimize surgical stress and reduce operating time and blood loss, as well as reduce the risk of reoperations due to implant failure.
Aim: Our primary objective was to investigate whether there is a difference in patient reported outcome measures between patients treated with instrumented fusion versus uninstrumented fusion, in patients who undergo surgery for degenerative spondylolisthesis. Secondary objectives was to investigate any differences in fusion rates and reoperation rates.
Materials and Methods: A randomized controlled, single center, open label trial was conducted on patients with symptomatic single-level degenerative spondylolisthesis of 3mm or more. All patients had undergone at least 12 weeks of unsuccessful conservative treatment prior to enrollment. Patients were randomly assigned 1:1 to decompression and fusion with or without supplementary instrumentation. The primary outcome measure was the Oswestry Disability Index (ODI), secondary outcome measures were duration of surgery, length of stay in hospital and reoperation rates within 2 years. Fusion rates were evaluated by fine-slice CT-scans at 1-year post-operative.
Results: 108 patients were included in the study. Mean age at time of surgery was 72 and 85% were women. The mean change in ODI at 2 year follow up was -22.1, -21.8 in the instrumented and -22.3 in the uninstrumented group, mean difference of 0.5 (95% CI, -7.7;6.8). A successful fusion was achieved by 94.3% of patients in the Instrumented group, and 31.4% in the un-instrumented group, we found one re-operation (1.9%) in the Instrumented group and 7(13.2%) in the uninstrumented group p=0.031.
Interpretation / Conclusion: In this trial comparing the outcome and complications in patients who underwent lumbar fusion with or without supplementary instrumentation, we found no difference in patient reported outcomes. Patients in the uninstrumented group had a significantly lower fusion rates and higher reoperation rates after 2 years.

106. An assessor-blinded randomized controlled trial investigating complications and functional outcome of non-operative vs. operative treatment of unstable distal radius fractures in patients older than sixty-five years
Rikke Thorninger ¹, Daniel Wæver ¹, Martin Lind ², Michael Tjørnild ¹, Jan Duedal Rölfing ²
¹ Dept. of Orthopaedics, Regional Hospital Randers, ² Dept. of Orthopaedics, Aarhus University Hospital

Background: The national clinical guidelines (NKR) stipulate treatment with volar locking plate of distal radius fractures (DRF) based on radiological criteria after fracture reduction. The superiority of operative treatment vs. non-operative treatment has been questioned in recent years.
Aim: Primary aim: to compare complications of operative vs. non-operative treatment of unstable DRF fulfilling NKR-criteria for operative treatment with a volar locking plate. Secondary aim: to compare the functional outcome
Materials and Methods: Single-center, assessor-blinded randomized controlled trial of unstable DRF. 50 patients: volar locking plate, 2 weeks casting + 3 weeks orthosis. 50 patients: 5 weeks casting. Primary outcome measure: complications were assessed after 2, 5 weeks, 6, and 12 months. Secondary outcome measures: Quick-Dash, PRWHE, range of motion (ROM), EQ5D. Published protocol: PMID: 31253145, ClinicalTrials: NCT03716661
Results: 148 patients were screened from Nov 2019 – March 2021. 48 patients either did not want to participate, were cognitively unable, or did not live in the area. Of 100 randomized patients, 84 patients were available for full analysis. Median age was 74 years (range 65-92), 81 women/19 men, 42 right/58 left side, 87 retired, 86 ASA class 1 or 2. Complication rates did not statistical significantly vary between the operative and nonoperative groups, 20.9% (9/43) vs. 16.6% (7/42), p=0.78 (Fisher’s exact test). Complications were driven by sensory disturbances. 4 reoperations were performed: 2 non-operative group: carpal tunnel syndrome, 2 operative group: 1 carpal tunnel syndrome, 1 protruding screw causing extensor tendon irritation. Mean difference in Quick-DASH varied from -2.1 (-7-6) pre-injury to -4.4. (-13-4) at 12 months. At no timepoint the Quick-DASH and PRWHE was clinically relevant different between groups. Analyses of other secondary outcome measures were not included in this abstract.
Interpretation / Conclusion: Complication rates after operative and conservative treatment of DRF were similar. Volar plating did not statistical significantly improve the functional outcome after 6 and 12 months. These findings are in line with recent international RCTs and mandate a revision of NKR towards more conservative treatment.