DOS Best Papers
Mikkel Bek Clausen, Per Hölmich, Michael Rathleff, Thomas Bandholm, Karl Christensen, Mette Zebis, Kristian Thorborg
Department of Midwifery, Physiotherapy, Occupational Therapy and Psychomotor Therapy at Faculty of Health, University College Copenhagen; Sports Orthopedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Amager-Hvidovre Hospital, Institute for Clinical Medicine, Copenhagen University; Center for General Practice , Aalborg University; Physical Medicine and Rehabilitation Research-Copenhagen (PMR-C), Department of Physical and Occupational Therapy, Copenhagen University Hospital, Amager-Hvidovre; Section of Biostatistics, Department of Public Health, University of Copenhagen; Department of Midwifery, Physiotherapy, Occupational Therapy and Psychomotor Therapy at Faculty of Health, University College Copenhagen; Sports Orthopedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Amager-Hvidovre Hospital, Institute for Clinical Medicine, Copenhagen University
Background: In 2019, the British Medical Journal issued a strong recommendation against subacromial decompression surgery, leaving non-operative care as the only treatment option. Evidence-based guidelines recommend shoulder strengthening as key in non-operative care for subacromial impingement (SIS), but recent studies suggest that the dose of strengthening exercise is not sufficient in current care.
Purpose / Aim of Study: To assess the effectiveness of adding a large additional dose of home-based shoulder-strengthening exercises to current non-operative care.
Materials and Methods: In this double-blinded randomised controlled trial, we randomly allocated 200 consecutive patients with longstanding SIS (>3 months) to intervention (IG) or control (CG). The CG received usual non-operative care according to evidence-based clinical guidelines; the IG received the same plus an add-on intervention with the aim to at least double the total dosage of shoulder strengthening. The Shoulder Pain and Disability Index (SPADI, 0-100), external-rotation and abduction strength, and patient acceptable symptom state (PASS) was evaluated at baseline, 5-weeks, 10-weeks and four-months follow-up (primary end-point).
Findings / Results: Intention-to-treat and per protocol analyses showed no significant or clinically relevant between-group difference for the primary or other outcomes. From baseline to four-month follow-up, SPADI improved in both groups (intention-to-treat: CG 22.8 points, IG 22.1 points, mean between-group difference 0.6 points (95%CI -5.5 to 6.6)). Four months after randomization, only 54% (IG) and 48% (CG) had reached patient acceptable symptom state (p=0.4127).
Conclusions: Prescribing a large additional dosage of shoulder strengthening exercise, in addition to usual non-operative care for SIS, does not result in superior outcome. As the confidence limits for between group differences in shoulder disability did not surpass the margin of clinical relevance, it is unlikely that additional studies will alter this conclusion. Importantly, half of all randomised patients had unacceptable symptoms after four months of non-operative care, leaving a large and substantially disabled group of patients with no further options in the traditional health-care system.
Janni Kjærgaard Thillemann , Lene Dremstrup , Torben Bæk Hansen , Maiken Stilling
Department of Orthopaedics, Hospital Unit West; Department of Orthopaedics, Hospital Unit West; Department of Orthopaedics, Hospital Unit West; Department of Clinical Medicine, Aarhus University
Background: Cup failure is a major problem in
trapeziometacarpal (TMC) arthroplasties.
Primary press-fit bone fixation is important
for achievement of later osseointegration of
cementless implants. The articulating
trapezium surface is usually cut, leaving a
level cancellous surface for cup insertion.
The cortical bone is stronger, but cup
insertion in a saddle shaped surface may be
Purpose / Aim of Study: We aimed to compare primary cancellous
and cortical press-fit fixation of a new
conical shaped TMC cup design, and to
investigate the effect of cup diameter.
Materials and Methods: Thirty-two hydroxyapatite-coated conical
cup designs of 9mm and 10mm were
randomly allocated to cancellous or cortical
bone fixation in a 1:1:1:1 ratio. The saddle-
shaped bone from the forefeet of two-month
old pigs were dissected and rigidly fixed in
epoxy glue. Before press-fit fixation of the
cups, six tantalum beads of 1mm were
inserted in the bone. Cup migration was
evaluated with static radiostereometric
(RSA) radiographs, recorded at baseline
and repeated after cyclic-load tests
(Mark10), performed from 150N to 1050N
with 100N intervals.
RSA precision was evaluated by double-
examinations. The total translation (TT) was
calculated and an >0.5mm increase,
between two pressure load tests, was
defined as cup-failure.
Findings / Results: The precision of TT was 0.09 mm and the
random error was 0.12 mm. From 0N to
750N load , all cups had a TT of less than
0.5mm migration between each load cycle,
but the TT of cups with cancellous bone
fixation was higher (up to 0.25mm (CI95
0.12-0.37)) compared to cups with cortical
bone fixation (p<0.04).
In 9mm cups, a 250N pressure load
resulted in a higher TT of cancellous fixated
cups compared to cups with cortical bone
fixation (p=0.001), whereas the 10 mm cups
required to 550N to detect a difference
The Kaplan-Meier cumulative survival
estimate (at 1050N) was best for 10 mm
cortical fixated cups (88%; CI95 39-98) and
least for 9mm cancellous bone fixated cups
(13%; CI95 0-42).
Conclusions: Based on this experimental study, we
advise clinical use of the largest possible
size conical shaped cup in addition to
cortical bone fixation, when treating TMC
joint osteoarthritis with total TMC joint
Werner Hettwer, Chunsen Wu, Peter Horstmann, Claus Lindkær Jensen, Anders Krarup-Hansen, Michael Mørk Petersen
Orthopaedic Surgery, Rigshospitalet; Institute of Clinical Research, University of Southern Denmark; Orthopaedic Surgery, Rigshospitalet; Orthopaedic Surgery, Rigshospitalet; Department of Oncology, Herlev Gentofte Hospital; Orthopaedic Surgery, Rigshospitalet
Background: This study examined the effect of an occlusive wound closure product (Dermabond Prineo-22
skin closure system (Ethicon, Somerville, NJ, USA)) in a patient population at high risk for
prolonged wound discharge and found that it significantly reduced frequency, degree and
duration of this complication in comparison to conventional skin staples.
Purpose / Aim of Study: Prolonged wound discharge (PWD) is a common post-operative complication
of orthopaedic procedures and a risk factor for implant-related infection. Occlusive wound
closure (OWC) methods have previously been suggested to reduce or even prevent this
complication. However, conclusive evidence in support of this hypothesis is still lacking.
Materials and Methods: We performed a randomized controlled trial on 70 patients who underwent surgical
treatment for metastatic- or malignant hematologic bone disease involving the proximal
femur at our center between January 2017 and August 2018. At conclusion of the tumor
resection and endo-prosthetic reconstruction procedure, patients were randomized to either
OWC (n=35), using the Dermabond Prineo-22 skin closure system, or routine wound closure
with conventional skin staples (n=35).
Findings / Results: Skin closure with OWC resulted in a significantly lesser degree (p<0.0001) and
shorter duration of post-operative wound discharge (HR 2.89 [95% CI 1.6-5.05], p<0.0018).
Compared to staples, surgical wounds were already dry after a mean of 3.5 days (vs 6.1 days,
[95%CI 3.2-3.9 vs. 4.8-7.3], p<0.0001). PWD for 7 days or more was observed in 23% of
patients (n=8) in the Staples-group, but was entirely absent in the OWC-group (p<0.003). For
every four patients treated with OWC, one complication of PWD of 7 days or more was
prevented (NNT = 4).
Conclusions: This study provides strong evidence that occlusive wound closure (OWC)
significantly reduces degree and duration of wound discharge in patients undergoing tumor
resection and endoprosthetic reconstruction of the proximal femur and prevents PWD of 7
days or more in comparison to conventional skin staples.
Filip Gertz Lysdal, Thomas Bandholm, Janne Tolstrup, Mikkel Clausen, Stephanie Mann, Pelle Petersen, Thor Grønlykke, Uwe Kersting, Eamonn Delahunt, Kristian Thorborg
Health Science and Technology, Aalborg University; Physical Medicine and Rehabilitation Research—Copenhagen (PMR-C), Department of Physical and Occupational Therapy, Clinical Research Centre, and Department of Orthopedic Surgery, Amager-Hvidovre Hospital, Copenhagen University; National Institute of Public Health, University of Southern Denmark; School of Physiotherapy, Faculty of Health and Technology, University College Copenhagen; Physical Medicine and Rehabilitation Research—Copenhagen (PMR-C), Department of Physical and Occupational Therapy, Clinical Research Centre, and Department of Orthopedic Surgery, Amager-Hvidovre Hospital, Copenhagen University; Section for Surgical Pathophysiology 7621, Rigshospitalet, Copenhagen University; , Spraino ApS; Institute of Biomechanics and Orthopaedics, German Sport University Cologne; Institute for Sport and Health, University College Dublin; Department of Orthopedic Surgery, Sports Orthopedic Research Center—Copenhagen (SORC-C), Amager-Hvidovre Hospital, Copenhagen University
Background: Lateral ankle sprains (LASs) are common in indoor sports and high shoe-surface friction is considered a risk factor for non-contact LASs. Spraino is a novel Teflon-patch that is attached to the outside of sports shoes to minimise friction at the lateral edge, which could mitigate the risk of LAS.
Purpose / Aim of Study: We aimed to determine preliminary effectiveness (incidence rate and severity) and safety (harms) of Spraino when used to prevent LAS injury among indoor sport athletes.
Materials and Methods: In this exploratory, parallel-group, two-arm pilot RCT, 510 sub-elite indoor sport athletes with a previous LAS injury were randomly allocated (1:1) to Spraino or “do-as-usual”. Allocation was concealed and the trial was outcome-assessor-blinded. Match and training exposure, LASs and associated time-loss were captured weekly via text messages. Information on harms, fear-of-injury and ankle pain were also documented.
Findings / Results: 480 participants completed the trial, reporting a total of 151 LASs, of which 96 were categorised as non-contact, and 50 as severe. All outcomes favoured Spraino with incidence rate ratios of 0.87 (95% CI, 0.62-1.23) for all LASs; 0.64 (95% CI, 0.42-0.98) for non-contact LASs; and 0.47 (95% CI, 0.25-0.88) for severe LASs. Time-loss per LAS was also lower in the Spraino group (1.8 vs 2.8 weeks, p=0.014). Six participants reported minor harms because of Spraino.
Conclusions: Compared to usual care, athletes allocated to Spraino had a reduced risk of LAS injury and reduced time-loss, with only few reports of minor harms. The next step is to test these promising risk reductions in a confirmatory RCT.
Claus Varnum, Alma Bečić Pedersen, Johan Kärrholm, Ola Rolfson, Anne Marie Fenstad, Ove Furnes, Geir Hallan, Antti Eskelinen, Keijo Mäkelä, Søren Overgaard
, Department of Orthopaedic Surgery, Vejle Hospital, Department of Regional Health Research, University of Southern Denmark, and the Danish Hip Arthroplasty Register, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Denmar; , The Swedish Hip Arthroplasty Register and Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden; , The Swedish Hip Arthroplasty Register and Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden; , The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; , The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen and Department of Clinical Medicine, University of Bergen, Bergen, Norway; , The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen and Department of Clinical Medicine, University of Bergen, Bergen, Norway; , The Finnish Arthroplasty Registry, Helsinki and Coxa Hospital of Joint Replacement, Tampere, Finland; , The Finnish Arthroplasty Registry, Helsinki and Department of Orthopaedics and Traumatology, Turku University Hospital, Turku, Finland; , Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, and the Danish Hip Arthroplasty Register, Denmark
Background: Ceramic heads were introduced as an
alternative to metal heads in total hip
arthroplasty (THA) in order to reduce wear
and osteolysis which may result in aseptic
Purpose / Aim of Study: We investigated the risk of any revision of
ceramic-on-polyethylene compared to
metal-on-polyethylene bearings in primary
THA and secondly the risk of revision due to
Materials and Methods: The study population was identified from
the NARA dataset, and consisted of
310,177 patients who had undergone a
primary THA with a ceramic-on-
polyethylene or metal-on-polyethylene
articulation because of primary
osteoarthritis, femoral head
osteonecrosis, arthritis, or sequelae from
childhood hip disorders. The adjusted
relative risk (aRR) and 95% confidence
intervals for revision were assessed with
regression with the pseudo-value
approach and adjusted for sex, age,
diagnosis, year of surgery, fixation, and
femoral head size. Analyses were made
separately for ceramic-on-conventional
polyethylene (CoP) compared to metal-
on-conventional polyethylene (MoP), and
(CoXLP) compared to metal-on-
crosslinked polyethylene (MoXLP).
Findings / Results: CoP vs. MoP: 24,018 had CoP and 166,402
MoP bearings and were followed up to 20
years. At 20 years, the aRR for any revision
was 1.04 (1.01-1.07) for CoP compared to
MoP. There was no difference in aRR for
revision due to aseptic loosening.
CoXLP vs. MoXLP: 25,070 had CoXLP and
94,687 MoXLP bearings and were followed
up to 12 years. At 12 years, the aRR for any
revision was 0.99 (0.97-1.02) for CoXLP
compared to MoXLP. There was no
difference in aRR of revision due to aseptic
Conclusions: The risk of revision was increased by 4% in
CoP compared to MoP THAs at 20 years
but no difference was found for CoXLP
compared to MoXLP at 12 years. Our study
did not demonstrate any advantage of
ceramic heads over metal heads in the
medium- to long-term follow-up. A limitation
is that the NARA database does not contain
any information on type of ceramic material.
Thomas Falstie-Jensen, Anne Katrine Belling Sørensen, Janne Ovesen, Jeppe Lange
Orthopaedic department, Aarhus University Hospital; Orthopaedic department, Herlev-Gentofte Hospital; Orthopaedic department, Herlev-Gentofte Hospital; Orthopaedic department, Horsens Regional Hospital
Background: Several studies have confirmed the high rate of unexpected positive cultures (UPC) after aseptic revisions of failed shoulder replacements. Especially Cutibacterium acnes are often cultured. However, the impact of UPC on outcome is still largely unclear.
Purpose / Aim of Study: The aim of this prospective and nationwide Danish study was to examine if emergence of UPC had any impact on the patient reported outcome after revisions of failed shoulder replacements.
Materials and Methods: Consecutive patients revised with a standard component exchange without any pre- or perioperative suspicion of infection were included from 2014 to 2017. Patients were assessed at baseline and two years after revision with Oxford Shoulder Score (OSS, 0-48 points), a subscale OSS pain score (0-12 points) and range of motion. Biopsy-specimens were obtained at revision and cultured for 14-days. Emergence of UPC was defined as growth of the same bacteria in ≥3 cultures. If UPC emerged; patients were treated with oral antibiotics for 6 weeks.
Findings / Results: Of the 124 patients included, UPC emerged in 27 cases (22%) with Cutibacterium acnes accounting for 67% (18/27). At baseline the median OSS was 22 in both the culture negative and the UPC group. At follow-up the median OSS was 37 in the culture negative group and 35 in the UPC group. Similarly, at baseline forward elevation was 76 degrees in the culture negative group and 77 degrees UPC group; at follow-up elevation was 121 and 117 degrees in the two groups respectively. Both groups had a pain score of 4 at baseline and 10 at follow-up (higher score equals less pain). Consequently, no statistical differences in OSS, pain or range of motion were found at any timepoint between the two groups (p>0.05).
Forthermore, increases in OSS and forward flexion and decrease in level of pain were statically significant and clinically relevant in both groups .
Conclusions: We could not detect any impact of UPC on the OSS score, range of motion or level of pain either before or after revision of a failed shoulder replacement. Both the culture negative and the UPC group experience similar, statically significant and clinically relevant increase in OSS, forward flexion and decrease in level of pain after revision.
Michael Rindom Krogsgaard, John Brodersen, Karl Bang Cristensen, Volkert Siersma, Jonas Jensen, Christian Fugl Hansen, Lars Engebretsen, Håvard Visnes, Magnus Forssblad, Jonathan Comins
Section for Sports Traumatology M51, Bispebjerg and Freeriksberg Hospital; The Research Unit for General Practice and Section for General Practice, University of Copenhagen and Region Zealand; Section of Biostatistics, Department of Public Health, University of Copehagen; The Research Unit for General Practice , Copenhagen University; Section for Sports Traumatology M51, Bispebjerg and Frederiksberg Hospital; Section for Sports Traumatology M51, Bispebjerg and Frederiksberg Hospital; Orthopedic Clinic, University of Oslo Medical School, Oslo Sports Trauma Research Center; Norwegian Knee Ligament Registry, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen Norway, Oslo Sports Trauma Research Center, Norwegian School of Sports Sciences, Oslo Norway; Department of Molecular Medicine and Surgery, Stockholm Sports Trauma Research Center, Karolinska; Secton for Sports Traumatology M51, Bispebjerg and Frederiksbberg Hospital
Background: Patient-reported outcome measures
(PROMs) are important to evaluate the
results of many clinical studies.
Therefore, most PROMs are available
in versions that have been translated
and adapted to other languages. If
data from different countries or
cultures – for instance from the
different knee ligament reconstruction
registries – are compared or pooled, it
is necessary to have proof that the
measurement properties across the
different language versions are
comparable, meaning that there is no
cross-cultural differential item
Purpose / Aim of Study: As the Knee injury and Osteoarthritis
Outcome Score (KOOS) is commonly
used to compare treatment results
across Scandinavian countries, the
aim was to test if there is cross-cultural
DIF between the Danish, Norwegian,
and Swedish versions of KOOS.
Materials and Methods: From each of the Scandinavian knee
ligament reconstruction registries (in
Norway, Sweden, and Denmark) 150
preoperative KOOS questionnaires
from patients aged 18-37 years,
completed 2016-18 were obtained and
cross-cultural DIF was evaluated using
confirmatory factor analysis (CFA) and
Findings / Results: Assessment of cross-cultural DIF
across Denmark, Norway, and Sweden
for KOOS yielded different results for
the five subscales. The ADL subscale
did not show construct validity in any of
the three countries, making evaluation
of cross-cultural validity meaningless.
The Symptoms subscale was valid in
each country, but all items displayed
evidence of DIF. The Pain and Sport
subscales were valid in all countries,
but they exhibited DIF with respect to
some (but not all) items, and thus
conversion tables could be
constructed. The Quality of Life
subscale was valid in each country,
and no evidence of DIF was found.
Conclusions: There was DIF between the Danish,
Swedish, and Norwegian versions of
KOOS. For the two sub scales with
DIF for some but not all items
conversion tables were constructed.
These can be used if data are pooled
(e.g., from the three Scandinavian ACL
registries). Data from the sub scales
ADL and Symptoms cannot be pooled.
Data from the Quality of Life sub scale
can be pooled without conversion.