Session 13: Foredragskonkurrence

Fredag den 24. oktober
13:30 – 15:00
Lokale: Reykjavik/Stockholm/Copenhagen/Helsinki/Oslo
Chairmen: Casper Foldager / Søren Overgaard

132. Preparation of the femoral bone cavity for cementless stems: Broaching versus Compaction. A 5 year randomized RSA and DXA study of 40 bilateral 1-stage operations
Mette Holm Hjorth , Maiken Stilling , Kjeld Søballe , Poul Torben Nielsen, Poul Hedevang Christensen, Søren Kold
Department of Orthopaedics , Aarhus University Hospital

Background: Experimental studies have shown superior implant fixation after bone compaction (C) compared to conventional broaching (B).
Purpose / Aim of Study: To investigate potential advantages and disadvantages of C compared to B in a randomized clinical trial (RCT)
Materials and Methods: 1-stage bilateral cementless THA (Bi-Metric, Biomet) was performed in 20 patients (13 M), mean age 58 (36-70) years. Patients were randomized to bone preparation with C on one side and B on the other side. Patients were followed with RSA and DXA at baseline, 6 and 12 weeks, 1, 2 and 5 years. The subjective part of Harris Hip Score (HHS) and complications/revisions throughout the observation period were obtained at mean 6.3 (3-9.5) years after surgery.
Findings / Results: At 6 weeks, mean absolute mean medio/lateral translations of 0.22 (CI: 0.12 to 0.32) mm in the C group was higher (p=0.04) than 0.11 (CI: 0.07 to 0.16) mm in the B group. At 5 years, the difference was more pronounced (p=0.01) with mean absolute medio/lateral translations in the C group of 0.34 (CI: 0.18 to 0.39) mm versus 0.13 (CI; 0.05 to 0.28) mm in the B group. At 2 years, mean values of percentage change in periprosthetic bone since baseline in Gruen zone 3 was inferior in the C group of 92.6 (CI: 88.1 to 97.1) % versus 100.7 (CI: 93.6 to 107.8) % in the B group (p=0.04). Intraoperative fractures occurred in 2/20 in the C group and in 0/20 in the B group (p=0.02). Clinical outcomes of HHS and dislocations (1 C, 2B) were similar between groups (p>0.59). No stems were revised at 5 years after surgery.
Conclusions: Bone compaction as compared to broaching prior to insertion of the cementless Bi-Metric femoral stem results in more absolute medio/lateral translation, starting already 6 weeks and continuing until 5 years follow-up. In this RCT intraoperative femoral fractures only occurred with bone compaction.

133. Bone autograft versus recombinant human BMP-2 (rhBMP-2) at bone docking-site in tibial bone transport. A randomized clinical trial (RCT).
Søren Kold, Martin Lind, Susanne Jølck, Knud Christensen
Department of Orthopaedics, Aalborg University Hospital

Background: Bone autograft is applied at the bone- docking site to increase the union-rate and decrease the time to union after bone transport. However, harvesting of the bone autograft results in donor-site morbidity. rhBMP-2 might replace the need for bone autograft.
Purpose / Aim of Study: We investigated the union-rate and the risk of refracture of the bone docking site treated with open debridement and application of either bone autograft or rhBMP-2.
Materials and Methods: 41 patients treated for segmental defects of the tibia with bone transport in a circular frame were randomized to either bone autograft (n=21) or rhBMP-2 (n=20) at the docking site. Patients were followed with monthly radiographs. Union was defined as presence of bone callus in 3 out of 4 cortices as well as bony bridge in 3 out of 4 cortices. The minimum follow-up after frame removal was 12 months.
Findings / Results: Radiographic union occurred in 21 out of 21 treated with autograft and in 20 out 20 treated with rhBMP-2. Mean time to union in months was 7 (range: 4 – 9) with autograft and 7 (range: 4 – 9) with rhBMP-2. Mean time in hospital stay in days was 6 (range: 2 – 12) with autograft and 5 (range 1 – 16) with rhBMP-2. There were no clinical signs of infection at the docking site in either group. Refracture at the docking site after frame removal occurred in one patient in the autograft group compared with 2 patients in the rhBMP-2 group (p=0.5). The risk of refracture was higher when the docking site was located at the mid- diaphyseal tibia (3 out of 15) compared to the metaphyseal tibia (0 out of 26) (p=0.02).
Conclusions: No differences in radiographic union rate or time to union were found between autograft and rhBMP-2. Refracture at the docking site occurred in 3 out of 41 cases, and mid- diaphyseal docking might carry a higher risk of refracture compared with metaphyseal docking.

134. Pharmacokinetics of Cefuroxime in Bone, Subcutaneous Tissue and Plasma – Comparison of Continuous versus Short-term Infusion
Mikkel Tøttrup, Mats Bue , Kurt Fuursted, Tore Forsingdal Hardlei, Kjeld Søballe, Hanne Birke-Sørensen
Department of Orthopaedic Surgery and Orthopaedic Research Unit in Aarhus, Hospitalunit Horsens and Aarhus University Hospital; Department of Orthopaedic Surgery Orthopaedic Research Unit in Aarhus, Hospitalunit Horsens and Aarhus University Hospital; , Statens Serum Institute; Department of Clinical Biochemistry, Aarhus University Hospital; Department of Orthopaedic Surgery, Aarhus University Hospital; Orthopaedic Research Unit, Aarhus University Hospital

Background: The relatively short half-lives of most beta-lactams suggest that continuous infusion (CI) of these time-dependent antibiotics may be favourable compared to short-term infusion (STI). Nevertheless, only limited pharmacokinetic (PK) data is available to support this theory, particularly in solid tissues like bone.
Purpose / Aim of Study: To obtain PK parameters of cefuroxime in plasma, subcutaneous tissue (SCT) and bone in pigs receiving 1500 mg of cefuroxime administered either as STI or as CI, and to compare time above minimal inhibitory concentrations (T > MIC) between the two groups.
Materials and Methods: Twelve pigs were included. Each animal was randomly assigned to receive 1500 mg of cefuroxime either as STI or CI. Measurements of cefuroxime were conducted in plasma, SCT, cancellous and cortical bone every 30 min. The measurements in solid tissues were conducted using microdialysis. A two-compartment population model was fitted to the drug concentration data separately for the different tissues using a non-linear mixed effects regression model. Key pharmacokinetic parameters and T > MIC were estimated using Monte Carlo simulations.
Findings / Results: Except for SCT in the STI group, tissue penetration was impaired for all tissues. The poorest tissue penetration was found in bone. Both tissue area under the curves and tissue penetration ratios generally appeared to be lower in the CI group. Nevertheless, significantly longer T > MIC was found for CI up until MICs of 4, 2, 2 and 0.5 μg/mL for plasma, SCT, cancellous and cortical bone respectively.
Conclusions: CI of beta-lactams with short half-lives may be favourable compared to STI if dosed appropriately. The poorest tissue penetration was found in bone. The high rate of treatment failure for osteomyelitis may therefore partly be attributable to impaired target site penetration of antibiotics.

135. Methylprednisolone reduce pain and decrease knee swelling in the first 24 hours after fast-track Oxford unicompartmental knee arthroplasty
Søren Rytter, Maiken Stilling, Stig Munk, Torben Bæk Hansen
Department of Orthopedics , Holstebro Regional Hospital, Hospital Unit West, Denmark

Background: Unicompartmental knee arthroplasty (UKA) operated with minimal invasive surgery (MIS) results in less operative trauma and faster patient recovery than after a conventional total knee arthroplasty. Despite an increased focus on multimodal analgesic strategies there is still a substantial level of patient-reported pain in the early post-surgical period after MIS UKA.
Purpose / Aim of Study: The purpose of the study was to evaluate the effect of a single preoperative dose of systemic methylprednisolone (MP) on acute post-surgical pain after fast-track MIS Oxford UKA.
Materials and Methods: 72 patients in 2 consecutive series undergoing unilateral UKA were included in a prospective cohort study. Patients (n=35) in the treatment group received a single preoperative dose of systemic MP 125 mg whereas the control group (n=37) did not. Otherwise there was no difference in the operative and postoperative treatment. Outcome measures were post-surgical pain at rest and during walking, consumption of opioids for pain rescue, knee swelling and knee range of motion. Complications were monitored until 4 months after surgery.
Findings / Results: In the first 24 hours after surgery the MP group had less pain at rest (p=0.000) and during walking (p=0.000), and less consumption of opioids (p=0.01) in comparison with the control group. Furthermore, the MP group had 2.2 cm less knee swelling (p=0.02) in the 1st postoperative day, and also better (p=0.004) knee extension, whereas flexion was similar (p>0.68) between groups. No serious complications were associated with the treatment.
Conclusions: A single preoperative dose of 125 mg systemic MP significantly reduce post- surgical pain and opioid consumption and decrease knee swelling in the first 24 hours after fast-track MIS Oxford UKA.

136. Physical activity and return to work after fast-track total hip replacement with or without supervised rehabilitation. Results from a randomized controlled trial.
Lone Ramer Mikkelsen, Inger Mechlenburg, Kjeld Søballe, Lene Bastrup Jørgensen, Thomas Bandholm, Annemette Krintel Petersen
Interdisciplinary Research Unit, Elective Surgery Centre, Silkeborg Regional Hospital ; Department of Orthopaedic Surgery, Aarhus University Hospital; (1)Physical Medicine & Rehabilitation Research – Copenhagen (PMR-C), Department of Physiotherapy, (2, Copenhagen University Hospital, Hvidovre; (1)Department of Physiotherapy- and Occupational Therapy, (2)Centre of Research in Rehabilitation (C, (1)Aarhus University Hospital, (2)Aarhus University

Background: Total hip replacement (THR) results in pain reduction and functional improvements. However, it is suggested that these improvements are not followed by increases in physical activity level and return to usual activities postoperatively. Furthermore, it is unknown whether supervised rehabilitation affects the activity level as well as return to work after THR.
Purpose / Aim of Study: To investigate whether supervised progressive resistance training during the first 10 weeks after THR affects the change in physical activity level from baseline to 6 months after THR and early return to work.
Materials and Methods: 73 THR patients were randomly assigned to a control group (CG, home based exercise) or intervention group (IG, supervised resistance training in addition to home based exercise). Preoperative, 6 and 12 months postoperative self-reported physical activity was measured in metabolic equivalents (METS) with the Physical Activity Scale (PAS) and days until return to work.
Findings / Results: Follow up was completed by 62 patients (85%). Changes in PAS scores from baseline to 6 months follow up were, mean [95% CI]: IG: 6.32 [3.5;9.1] METS and CG: 0.85 [-2.8;4.5] METS (p=0.02). Sick leave duration in the working population of the sample (n=25) were, median [range]: IG: 46 [6;161] days and CG: 57 [7;146] days (p=0.49).
Conclusions: Patients performing supervised resistance training in addition to home-based exercise increased their self-reported physical activity level more than patients performing home-based exercise only, during 6 months after THR however, the difference was eliminated at 1 year follow up. No significant difference was found concerning return to work.

137. Preoperative embolization in surgical treatment of spinal metastases: single-blind, randomized controlled clinical trial of efficacy in decreasing intraoperative blood loss
Caroline Clausen, Benny Dahl, Susanne C Frevert, Lars Valentin, Michael B Nielsen, Lars Lönn
Department of Radiology, Rigshospitalet and University of Copenhagen ; Department of Orthopaedic Surgery, Rigshospitalet and University of Copenhagen

Background: An increasing number of patients undergo surgical treatment for symptomatic spinal metastasis. No randomized study has evaluated the effect of preoperative embolization.
Purpose / Aim of Study: To assess whether preoperative arterial embolization reduce blood loss, blood transfusion, and duration of surgery in surgical treatment of metastatic spinal cord compression.
Materials and Methods: This single-blind, randomized (1:1), controlled, parallel-group, single-center trial was approved by the national committee on biomedical research ethics and preregistered. Informed consent was obtained and the study period was from May 2011 until March 2013. All participants were scheduled for decompression and posterior thoracic/lumbar spinal instrumentation. They were randomly assigned to either 1) preoperative arteriography and embolization – the embolization group or 2) preoperative arteriography – the control group. Primary outcome: intraoperative blood loss. Secondary outcomes: perioperative blood loss, allogenic RBC transfusion and duration of surgery. Analyses were by intention-to-treat (ITT).
Findings / Results: Forty-five randomized patients were available for the ITT. Mean intraoperative blood loss did not differ significantly (P = .270) between the embolization group (618 ml [SD, 282 ml]) and the control group (735 ml [SD, 415 ml]). Neither did perioperative blood loss and allogenic RBC transfusion. The duration of surgery, however, was significantly shorter in the embolization group (P = .031): median 90 minutes (range, 54-252) vs. 124 minutes (range, 80-183). Thirty-four of 45 metastases (76%) were hypervascular.
Conclusions: Preoperative embolization does not result in a reduction of intraoperative blood loss, perioperative blood loss and blood transfusion, but reduces the duration of surgery for symptomatic metastatic spinal cord compression.

138. HA-coating may decrease screw migration in the femoral head following hip fracture surgery – a double blinded RSA study
Henrik Palm, Kim Holck, Steffen Jacobsen, Søren Bøvling, Torben Bæk-Hansen, Maiken Stilling
Dept. of Orthopedics, Copenhagen University Hospital Hvidovre

Background: Sliding hip screw (SHS) migration in the femoral head after hip fracture surgery may lead to fracture collapse and/or screw cut- out necessitating a reoperation.
Purpose / Aim of Study: To investigate if a hydroxyapatite (HA) coated thread could reduce SHS migration.
Materials and Methods: 37 patients (31 female) at mean age 79 (range 56-96) years with stable trochanteric fractures were operated in two centers with a 4-hole 135-degrees SHS (HipLoc, Biomet) and randomly allocated to sliding screws with either a non-coated (n=19) or an HA- coated (Bonemaster, Biomet) screw-thread (n=18). Patients and assessors were blinded for choice of screw. Patients were followed after 1.5, 3 and 6 months with marker-based RSA comparing migration between 1) The sliding screw marked with 4 beads and 2) The femoral head marked with 3-5 beads inserted through the drilled SHS canal. Demographic, surgical and radiological parameters (TAD, fracture reduction sum and screw placement in the femoral head) were prospectively collected.
Findings / Results: Mean TAD of 2.1 (sd 0.66) mm, fracture reduction sum in AP and LA of mean 0.66 (sd 0.87) mm and screw position in the femoral head were similar between groups (p>0.28). Screws with HA-coated thread had less varus rotation (4.1 vs. 0.3 degrees, p=0.03) after 1.5 months and a reduced lateral translation (0.6 vs. 0.01 mm, p=0.046) after 6 months, with a tendency after 1.5 months (0.4 vs. 0.2 mm, p=0.08). Other translations and rotations were not different and there were no correlation to radiological parameters. No cut-outs or revisions.
Conclusions: Coating the SHS thread with HA reduced screw migration in the femoral head at short- term follow-up. Missed late follow-ups might underpower statistics at 3 and 6 months. Migrations were small and larger clinical studies are warranted for evaluation of long- term benefits.