Session 4 : YODA Best Paper

15. November
11:00 - 12:00
Lokale: Auditorium
Chair: Christian Bredgaard Jensen and Claus Varnum

31. Field sterility is a safe procedure in carpal tunnel release
Tobias Christian Bisgaard1, Kjærgaard Thillemann Janni 1,2, Bæk Hansen Torben 1,2
1. Department of Orthopaedics, University Clinic for Hand, Hip and Knee Surgery, Gødstrup Hospital, Herning 2. Department of Clinical Medicine, Aarhus University

Background: In February 2023, field sterility (FS) was implemented for outpatient surgery of minor hand surgery at Gødstrup Hospital, as these procedures may be performed safely in FS alone.
Aim: We aimed to compare infection rates after treatment of carpal tunnel syndrome (CTS) performed in standard sterility with full surgical draping to FS alone.
Materials and Methods: In a retrospective cohort study 140 patients (58 men) with a mean age of 61 years (range 21-95) were included after surgical treatment of CTS in FS alone, performed as open or endoscopic carpal tunnel release (CTR). In 2022, the year before implementing FS, 213 patients (81 men) with a mean age of 63 years (range 17-90) underwent similar surgical procedures under standard sterility settings and were selected as control group. Infection was registered from the hospital data charts, including samples performed at the hospital or by the patient’s general practitioner. In case of a positive bacteriological sample within the first 14 days after surgery, infection was registered either as superficial without needs for surgery or deep with the need of surgical intervention.
Results: The control group and FS group were comparable on age, gender, operated side and surgical technique. There were 4 superficial infections (3%) in the FS group, which was a significantly lower rate compared to 16 superficial and 1 deep (open CTR) infection (12%) in the control group (p=0.046). The main agent causing infection was streptococcus aureus (81%). Three superficial infection was diagnosed after endoscopic CTR in 142 patients (2%), which is significantly less compared to 18 infections diagnosed after open CTR in 211 patients (9%), regardless the sterility procedure (p=0.03). However, patients treated by open CTR was mean 22 years (95% CI 19-25) older open CTR patients (p=0.000).
Interpretation / Conclusion: Field sterility for a minor hand surgical procedures including open and endoscopic CTR, is safe and without increased risk of infection. Thus, FS reduces the amount of draping’s and thereby the costs. Furthermore, endoscopic CTR surgery technique showed less infection compared to the open technique but may be associated to higher age.

32. New reference values of central knee anatomy for 8-16-year-old children
Emma Hvidberg1,2, Bjoern Vogt3, Jan Duedal Rölfing1,2, Georg Gosheger4, Bjarne Møller-Madsen1,2, Ahmed A Abood1,2, Veronika Weyer-Elberich5, Andrea Laufer3, Toporowski Gregor3, Robert Rödl3, Adrien Frommer3,
1. Danish Pediatric Orthopedic Research, Aarhus University Hospital, Denmark; 2. Children’s Orthopedics and Reconstruction, Aarhus University Hospital, Denmark; 3. Pediatric Orthopedics, Deformity Reconstruction and Foot Surgery, Muenster University Hospital, Germany; 4. General Orthopedics and Tumor Orthopedics, Muenster University Hospital, Germany; 5. Institute of Biostatistics and Clinical Research, University of Muenster, Germany

Background: For correction of leg length discrepancy or angular deformity of the lower limb in skeletally immature patients temporary or permanent (hemi-)epiphysiodesis can be employed. These are reliable treatments with few complications. Recently, radiographic analysis of treatment related alternations of the central knee anatomy gained interest among pediatric orthopedic surgeons. To date the comparison and adequate interpretation of potential changes of the central knee anatomy is limited due to the lack of defined standardized radiographic references.
Aim: The goal of the study is to define new radiographic refences for the central knee joint anatomy in skeletally immature patients.
Materials and Methods: 503 calibrated long standing anteroposterior radiographs of 254 children aged 8-16 years with leg length discrepancy < 1 cm and mechanical axis deviation < 2 cm were retrospectively analyzed during the study period (2011-2020). Four specific radiographic parameters were assessed: femoral floor angle, tibial roof angle, width of femoral physis, and femoral notch- intercondylar distance. Parameters were analyzed in different age groups (8-10 years, 11-12, 13-14, 15-16) and by sex.
Results: All observed parameters were normally distributed with a mean age of 12.4 years (standard deviation (SD) 2, 95% confidence interval (CI) 12.2 to 12.6). The mean femoral floor angle was 142° (SD 6, CI 142 to 143), mean tibial roof angle was 144° (SD 5, CI 144 to 145), the mean width at femoral physis was 73 mm (SD 8, CI 72 to 74) and mean femoral notch-intercondylar distance was 8 mm (SD 5, CI 7.5 to 8.3). There were no clinically relevant age and gender dependent differences. The estimated intraclass correlation coefficient values were excellent for all measurements.
Interpretation / Conclusion: This is the first description of standardized reference values regarding the central and sagittal knee joint anatomy in children. We suggest considering values within the margin of two standard deviations (SD) as physiological range. These parameters might help to identify secondary deformities during growth modulating treatment such as epiphysiodesis.

33. Dynamic real-time evaluation of intra- and postoperative cefuroxime tissue concentrations in spine deformity surgery after repeated weight-dosed intravenous administration.
Magnus A. Hvistendahl1,2, Mats Bue1,2,3, Pelle Hanberg1,2, Maiken Stilling1,2,3, Kristian Høy3
1 Aarhus Denmark Microdialysis Research (ADMIRE), Orthopaedic Research Laboratory, Aarhus University Hospital 2 Department of Clinical Medicine, Aarhus University 3 Department of Orthopaedic Surgery, Aarhus University Hospital

Background: Prophylactic antibiotics are central in preventing postoperative infections, yet knowledge on intra- and postoperative spine tissue concentrations in clinical settings remains limited. Thus, current antibiotic prophylactic regimens are based on empirical knowledge, surrogate measures (e.g. plasma samples), non-clinical evidence (experimental models), or inferior methodology (e.g. tissue specimens).
Aim: The aim was to dynamically investigate intra- and postoperative cefuroxime spine tissue concentrations after repeated weight- dosed administration in patients scheduled for spine deformity surgery.
Materials and Methods: Twenty patients (15 F, 5 M) were included (median age (range): 17.5 years (12-74), mean BMI (range): 22 (16-38), mean surgery time (range): 4 h 49 min (3 h 57 min-6 h 9 min). Repeated weight-dosed cefuroxime was administered intravenously (20 mg/kg) to all patients on average 25 min before surgery and again 4 hours later. Microdialysis catheters were placed for sampling in vertebral bone, paravertebral muscle, and subcutaneous tissue as soon as possible after surgery start. Upon wound closure, the vertebral bone catheter was removed, and two additional catheters were placed in the profound and superficial part of the incision. Microdialysates and plasma samples were obtained for up to 12 hours. The primary endpoint was time above the minimal inhibitory concentration of 4 µg/mL in percent (%T>MIC 4) of a) patients’ individual surgery time, b) first- and c) second dosing interval.
Results: Mean %T>MIC 4 (range) of a) Patients’ individual surgery time was 100% (100-100%) in all investigated tissues. b) The first dosing interval was 93% (93- 93%) in vertebral bone, paravertebral muscle, and subcutaneous tissue, and 99% (99-100%) in plasma. c) The second dosing interval was 87% (52- 100%) in paravertebral muscle, 89% (52- 100%) in subcutaneous tissue, 91% (71- 100%) in the profound incision, 94% (72- 100%) in the superficial incision, and 71% (42-100%) in plasma.
Interpretation / Conclusion: Repeated weight-dosed cefuroxime administration resulted in sufficient cefuroxime spine tissue concentrations (>4 µg/mL) both intra- (up to 6 hours) and postoperative (up to 7.5 hours) in spine deformity surgery.

34. Functional performance tests, clinical measurements, and patient reported outcome measures are separate outcomes after primary anterior cruciate ligament reconstruction
Mustafa Hamid Hussein Al-Gburi1, Jakob Bredahl Kristiansen2, Karl Bang Christensen3, Michael Rindom Krogsgaard1
1 Section for Sports Traumatology, Department of Orthopedic Surgery, Bispebjerg and Frederiksberg University Hospital, Copenhagen, Denmark 2 Department of Physical and Occupational Therapy, Bispebjerg and Frederiksberg University Hospital, Copenhagen, Denmark 3 Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark

Background: The technical results after anterior cruciate ligament reconstruction (ACLR) are evaluated by laxity measures, the functional results by performance tests, and patients’ perception by patient-reported outcome measures (PROMs). It is unknown whether one of these can represent outcome, or if they should all be reported.
Aim: To analyze the correlations between the three types of outcome one year after primary ACLR.
Materials and Methods: Consecutive adult patients who had an ACLR between 1.1.2019 and 31.12.2021 were offered a one-year follow-up by an independent observer. Preoperative information about laxity, peroperative information about graft size and pathology of menisci/cartilage and treatment of this (if present), and postoperative information about complications were registered. At one-year follow-up independent observers measured clinical and instrumented knee stability, range of motion, and results of four different hop tests. Patients completed 4 PROMs (IKDC, KOOS, Lysholm and KNEES-ACL) and Tegner activity scale, reported pain scores and answered anchor questions regarding satisfaction and willingness to repeat the operation. Spearman correlations were calculated between the Lysholm score, IKDC-score, each domain score in KNEES-ACL and KOOS and the other outcome modalities. The strength of the correlations were interpreted as: 0.00–0.30 negligible, 0.30– 0.50 low, 0.50–0.70 moderate, 0.70–0.90 high and 0.90–1.00 very high
Results: A total of 190 adults attended the one-year follow-up and 151 had all assessments. There were only few positive and weak correlations between performance tests and PROMS and between clinical measurements and PROMS (r = 0.00 – 0.38), and the majority were of negligible strength.
Interpretation / Conclusion: There was no clinically important correlation between scores obtained by PROMs, a battery of functional performance tests and instrumented laxity of the knee at 1-year follow-up after ACLR, meaning that the various modalities represent different aspects of outcome, and that one type of outcome cannot represent all. This is an argument for always to include and report all three types of outcomes, and conclusions based on one type of outcome may not be sufficient.

68. The effect of obesity on prosthesis orientation and positioning in patients with hip osteoarthritis following total hip arthroplasty
Hans Christian S. Vistisen1, Mads J. Rex1, Mogens Laursen1, Thomas Jakobsen1
1. Interdisciplinary Orthopaedics, Aalborg University Hospital

Background: In total hip arthroplasty (THA), orientation of prosthesis components is of the utmost importance regarding hip stability, component wear and failure rates. In literature, obesity has been related to increased leg length discrepancy (LLD) and poorer placement of the acetabular component as well as increased risk of dislocation.
Aim: The aim of this study was to investigate the effect of obesity on prosthesis component orientation and positioning in hip osteoarthritis patients operated with THA.
Materials and Methods: A retrospective observational study on 614 THAs at Farsoe Hospital in the period 2015- 2022, distributed in an obese (BMI >35) and a reference group (BMI 20-25). Pre- and postoperative x-rays were assessed for cup positioning and orientation, stem alignment and LLD according to standards in the TraumaCad software. Cup orientation was tried in safe zones of; +/-15 and +/-5 degrees from the optimal orientation suggested by literature. Crude and adjusted multiple linear regression models were used to detect statistically significant differences between the two groups.
Results: In the reference group, 58.5% of cups were within the Lewinnek safe zone versus 53.8% in the obese group. Adjusted linear regression models proved significantly lower odds ratio for the cup to be within the +/-5 safe zone in the obese group (0.61, p-value = 0.003), while there was no difference in the +/-15 safe zone (0.97, p-value =0.89). The obese group had significantly lesser anteversion (-4.04, p- value<0.001) and greater inclination of the cup (2.60, p-value = 0.0014). Furthermore, the obese group had a greater increase in lateral offset (1.76, p-value=0.016). There was no difference in stem alignment or LLD. Mean LLD was 5.8 mm with a SD of 4.5 mm in the obese group and 5.6 mm with a SD of 4.6 mm in the reference group.
Interpretation / Conclusion: This study found a lesser percentage of acetabular components inside the Lewinnek safe zone in the obese group. In the adjusted models, the obese group had a significantly lower odds ratio for the cup being in the +/-5 safe zone for cup orientation. The obese group had a significantly greater increase in lateral offset. There was no difference in stem alignment or LLD.

36. Computer-assisted intramedullary nailing of intertrochanteric fractures failed to improve the tip-apex distance and lag screw protrusion
Rasmus Holm Hansen, Jan Duedal Rölfing, Christian Lind Nielsen, Ole Brink, Per Hviid Gundtoft
Department of Orthopaedics, Aarhus University Hospital

Background: Intertrochanteric femoral fractures are commonly treated with intramedullary nails (IMN). A common complication of this treatment is lag screw cut-out. A tip-apex distance (TAD) of more than 20-25 mm is associated with an increased risk of cut-out. The Stryker ADAPT system is a computer-assisted navigation system, which has been reported to decrease the TAD.
Aim: To prospectively assess if ADAPT decreases the TAD and lag screw protrusion after implementation in our department.
Materials and Methods: All patients with intertrochanteric fractures treated with an IMN were prospectively included between 1 September 2020 and 12 March 2022. The cohort was divided in three periods: 54 patients operated before ADAPT implementation (pre-ADAPT), 50 patients with ADAPT during its implementation (ADAPT-period), and 59 patients without ADAPT after we discontinued its use (post-ADAPT). The TAD and lag screw protrusion beyond the lateral cortex were manually measured in accordance with previously published studies of TAD.
Results: The median TAD in the three periods were 17.0 mm (8-31), 15.5 mm (9-30), and 18.0 mm (11- 32) respectively. Thus, we found no statistically nor clinically relevant reduction of the TAD when using ADAPT compared with the pre-ADAPT period (p=0.62). In the pre-ADAPT period, 14 out of 54 patients had a TAD > 20 mm, while 10 out of 50 patients had a TAD >20 during the ADAPT-period. Importantly, ADAPT failed to reduce the number of outliers with TAD >20 mm (p=0.23) and TAD >25 mm (p=0.43, Chi-square test). Moreover, ADAPT did not significantly reduce the protrusion of the lag screw beyond the lateral cortex in the ADAPT period compared to the pre- and post-ADAPT periods.
Interpretation / Conclusion: ADAPT did not improve the TAD or lag screw protrusion during implementation. Importantly, it did not reduce the number of outliers and was thus discontinued at our department. We found no benefit to using the ADAPT system.