Postersession I
Onsdag den 22. oktober
11:00 – 12:00
Lokale: Reykjavik
Chairmen: Morten Bøgehøj / Henrik Morville Schroeder
139. One-year evaluation: Is there effect of 8 weeks supervised progressive resistance training after unicompartmental knee arthroplasty?
Peter Bo Jørgensen, Søren Bie Bogh, Signe Kierkegaard, Henrik Sørensen, Kjeld Søballe, Inger Mechlenburg
Orthopaedic Research, Aarhus University Hospital; Center for Quality, Region of Southen Denmark; Sports Science, Aarhus University
Background: Muscle atrophy and decreased muscle
strength is documented in early stages
of knee osteoarthritis and increases
with progression. Within the first weeks
after Unicompartmental Knee Arthroplasty
(UKA) an additional decrease in muscle
strength is found. That is the rationale
for early initiated resistance training.
Purpose / Aim of Study: To evaluate if there is effect of 8
weeks progressive resistance training
(PRT) after UKA assessed 1 year
postoperative.
Materials and Methods: 53 patients (26 males), median age 66
years, scheduled for UKA were randomized
to either 8 weeks supervised PRT (n=29)
or 8 weeks standard home exercise (HE)
program (n=24). PRT was initiated within
the first week after UKA and performed
2/week for 8 weeks in training machines.
Preoperative assessment, 2-months and
1-year follow-up were performed for leg
press power, asymmetry in gait, walking
speed and Knee injury and Osteoarthritis
Outcome Score (KOOS).
Findings / Results: 22 PRT and 18 HE-patients (73%)
completed 1-year follow-up and patients
in the PRT group participated in mean 11
of 16 training sessions. Leg press power
increased from baseline to 1-year follow
up (PRT: 29% and HE: 30%, p<0.04 in both
groups) and asymmetry was minimally
changed (PRT: 0,14% and HE: 0,29%) with
no between-group difference (p>0.53 and
power >0.89). Walking speed (PRT: 16%
and HE: 15%), KOOS symptoms (PRT: 21
point and HE: 15 point), KOOS pain (PRT:
38 point and HE: 32 point), KOOS ADL
(PRT: 29 point HE: 28 point) KOOS sport
(PRT: 33 point and HE: 42 point), KOOS
QoL (PRT: 39 point and HE: 32 point)
increased in both groups with no
between-group difference (p>0.42).
Conclusions: We found no additional effect of an
8-week PRT program compared to HE in
this patient group when assessed one
year after surgery.
140. Is gait velocity and gait quality associated with hip muscle strength in hip osteoarthritis patients scheduled for total hip arthroplasty?
Signe Rosenlund, Dennis Brandborg Nielsen, Søren Overgaard, Carsten Jensen, Anders Holsgaard-Larsen
Department of Orthopedic Surgery and Traumatology and Orthopaedic Research Unit, Department of Ortho, Køge Hospital and Odense University Hospital; Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology and Institute of Clini, Odense University Hospital and University of Southern Denmark
Background: Association between lower extremity
muscle strength and gait velocity has
been documented in healthy elderly
individuals but not in patients with end-
stage hip osteoarthritis (OA). Three-
dimensional (3D) gait analysis help
identify gait pathology. But the complexity
and amount of data collected during gait
analysis lead to challenges when
interpreting these. Gait Deviation Index
(GDI) summarizes the lower limb
kinematic data and describes 98% of the
variation in gait.
Purpose / Aim of Study: The aim of this study was to investigate
associations between hip muscle strength,
gait velocity, and GDI in patients with end-
stage hip OA.
Materials and Methods: A cohort of 20 consecutive patients all
with unilateral end-stage hip OA
scheduled for THA (5 women and 15
men; age 61± 5.8 years; BMI 28.1 ± 3.4
(mean ± SD)). All completed 3D gait
analysis and performed isometric
maximal voluntary hip muscle strength
(MVC) tests (hip-flexion, -abduction and -
extension). A GDI of 100 indicates no gait
pathology and a 10 point change
represents 1 SD from the reference
group. Linear regression analysis were
used to determine coefficient of
determination using GDI or gait velocity
as dependent variables and hip MVC as
the independent variables.
Findings / Results: A significant association (R2 = 0.43; p=0.03)
between gait velocity and hip MVC was
observed using multiple linear regression.
Furthermore, simple regression analysis
revealed a moderate association (R2 = 0.23;
p=0.03) between hip abduction and gait
velocity. However, no association between
GDI and hip MVC was found.
Conclusions: The present study confirms an association
between hip MVC and gait velocity for OA
patients scheduled for THA. However, no
association between hip MVC and gait
quality was shown. The present data
indicate that rehabilitation aimed at improving
hip muscle strength would be effective.
141. Objectively measured physical activity – reference data obtained from a Dutch population with a three-axial accelerometer
Signe Kierkegaard, Inger Mechlenburg, Bernd Grimm, Ide Heyligers, Rachel Senden
Orthopaedic Research, Aarhus University Hospital, Denmark; Department Orthopaedic Surgery & Traumatology, Atrium Medical Center, Heerlen, The Netherlands
Background: Self-reported physical activity (PA) is often
under/overestimated and influenced by
patient satisfaction and pain. Thus, PA after
surgery or rehabilitation should be measured
objectively, which is easily done using
ambulant accelerometer based activity
monitoring (AM). However a reference
database of AM parameters is currently
lacking.
Purpose / Aim of Study: To collect reference data of objectively
measured PA.
Materials and Methods: 59 Dutch healthy subjects, (37 females)
median aged 47.5 (21-66) years with no
restrictions in mobility were included. A
three-axial accelerometer was attached
during waking hours to the participants’
lateral thigh for four consecutive days. Data
was analysed using previously validated
algorithms in MatLab 7.10.0 ®. Median values
of the four days were calculated and the
results were stratified into age groups of
decades, 20-29 (30-39) 40-49 (50-59) and
60-69.
Findings / Results: Mean measurement time was 13.5 ±1.5
hours per day. Subjects were sitting median
64 (53) 59 (59) 57 %, standing 22 (32) 29
(26) 31 %, walking 9 (14) 13 (11) 12 % and
biking 0.5 (0.4) 0.02 (0.4) 0.5 % of the day.
Subjects walked on average 5217 (8447)
7666 (8474) 7030 steps per day and
performed mean 43 (63) 50 (45) 47 sit to
stand transfers a day. There was a
tendency towards the youngest group sitting
more and standing and walking less than the
older groups, but no statistically significant
differences were found between the age
groups.
Conclusions: The present data may serve as initial values
for a reference database. However, the
results are affected by a large variation in
PA and a small age range, which might
explain the lack of significant differences
between age groups. A larger reference
database need to be created where effects
of subject characteristics on PA can be
investigated and where people above 66
years are included as well.
142. Validation of intraoperative reported angle measurements in periactabular osteotomy
Sepp De Raedt, Inger Mechlenburg, Maiken Stilling, Marleen de Bruijne, Lone Rømer, Kjeld Søballe
Orthopaedic Research Unit, Aarhus University Hospital; BIGR/DIKU, Erasmus MC Rotterdam/University of Copenhagen; Department of Radiology, Aarhus University Hospital
Background: Periactabular osteotomy (PAO) has become
the treatment of choice for patients with
developmental hip dysplasia. However, it is
a technically demanding procedure and
achieving an optimal correction can be
difficult due to the lack of three-dimensional
(3D) feedback. The biomechanical guidance
system (BGS) provides the surgeon with
live 3D feedback.
Purpose / Aim of Study: To validate measurements obtained with the
BGS against manual measurements.
Materials and Methods: Patients underwent pre- and post-operative
CT imaging. Manual center-edge (CE),
acetabular index (AI), acetabular
anteversion (AcAV), posterior acetabular
sector (PASA) and anterior acetabular
sector (AASA) angle measurements were
performed. The lunate surface was
manually delineated and surgical planning
was performed. Initial automatic angle
measurements were recorded. After the
acetabular fragment was repositioned and
fixated, the BGS was used to obtain the
final angle measurements.
The difference between the manual and the
BGS reported angle measurements were
analyzed by statistical analysis. We report
the concordance correlation coefficient
(CCC), average difference, and the 95%
limits of agreement (LOA).
Findings / Results: Initial results for the first five patients
included were: CE angle: CCC: 0.93, Avg.
Diff.: 0.40, 95% LOA: -4.52;5.31. AI angle:
CCC: 0.98, Avg. Diff.: 0.17, 95% LOA:
-2.59;2.94. AcAV angle: CCC: 0.96, Avg.
Diff.: 0.68, 95% LOA: -2.30;3.66. PASA
angle: CCC: 0.92, Avg. Diff.: 0.82, 95%
LOA: -4.26;5.90. AASA angle: CCC: 0.98,
Avg. Diff.: 0.03, 95% LOA: -4.63;4.69.
Conclusions: Initial results show a good agreement
between manual and BGS reported angles
and are within the variation expected from
intra-rater variability. With further
development and validation, the system
may become a valuable tool to help the
surgeon achieve the optimal correction for
each patient.
143. Safety of Vitamin E infused high wall liners for routine use in primary THA: Single center, short term follow-up of 767 cases
Nanna Sillesen Hylleholt, Christopher Barr J., Peter Gebuhr, Henrik Malchau, Henrik Husted, Troelsen Anders
Department of Orthopedics Copenhagen University Hospital Hvidovre, Hvidovre Hospital; Harris Orthopaedic Laboratory, department of orthopedics, Massachusetts General Hospital, Harvard Medical School
Background: Vitamin E infused highly crosslinked
polyethylene liners (VEPE) offer the potential
for reduced wear and osteolysis. The
extended liners, including the high wall type,
leaving parts of the polyethylene uncovered,
have been hypothesized to result in
increased wear and the potential for liner
fracture. Introduction of new implants
should be monitored closely to capture any
signs of compromising patient safety.
Purpose / Aim of Study: The aim of this study was to determine the
short-term safety profile of high wall VEPE
for primary total hip replacement (THA),
focusing on liner related complications.
Materials and Methods: We included 767 consecutive THAs
operated from July 2010 to March 2013
with use of a high wall VEPE liner (E1,
Biomet). The preferred components used
were an uncemented cup (Exceed ABT,
Biomet (100 %) and an uncemented stem
(Bimetric, Biomet (98 %)). Majority of
heads were size 36mm (67 %) and
32mm (32 %).The data collected included
demographics, implant data,
complications, reoperations, and deaths.
Acetabular cup position was measured
using Martell Hip Analysis Suite in a
subgroup of 407 THAs. Length of follow-
up was 1.1-3.8 years.
Findings / Results: There were no revisions due to liner failure.
Revisions included 5 open reductions, 11
soft-tissue revisions for infection, 28
isolated stem revisions (periprosthetic
fractures), 2 isolated cup revisions, and 7
combined cup and stem revisions. The
subgroup with cup position measurements
showed 77% were in the combined
acceptable zone of cup abduction (30-55°)
and version (5-35°).
Conclusions: Early follow-up of routine use of VEPE high
wall liners for primary THA have not shown
any liner associated complications or
revisions. Continued monitoring of new
materials are important to capture any signs
of compromised patient safety.
144. Acetabular dysplasia increases risk for malpositioning of the acetabular component in Total Hip Arthroplasty (THA)
Kirill Gromov, Meridith Greene, Christopher Barr, Peter Gebuhr, Henrik Malchau, Anders Troelsen
Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Harris Orthopaedic Laboratory, Massachusetts General Hospital
Background: Persistent acetabular dysplasia (AD)
following periacetabular osteotomy (PAO)
has been hypothesized to increase the risk
for malpositioning of the acetabular
component that may subsequently lead to
higher rates of wear, dislocation and
impingement.
Purpose / Aim of Study: The purpose of this study was to investigate
whether AD is an independent risk factor for
cup malpositioning.
Materials and Methods: 839 primary THA patients, with pre and
postoperative pelvic radiographs, from 16
centers in the USA and Europe are enrolled
into a prospective 10year outcome study. All
patients were operated using an
uncemented Biomet® cup and a Biomet®
stem of surgeons’ choice. Patient
demographics and surgical parameters
were recorded. AD was assessed by
measuring lateral center edge (LCE) angle
and defined as LCE<25°. Cup positioning
was determined on postoperative AP pelvic
images using Martell Hip Analysis Suite.
Acceptable ranges were defined as 30-45°
abduction and 5-25°version. Multivariate
logistic regression analysis was performed
to calculate adjusted risk for cup
malpositioning.
Findings / Results: 504 (60%) acetabular cups were within the
abduction range, 608 (73%) were within the
anteversion range, and 377 (45%) were
within the range of both. Surgical approach,
presence of AD, and JSW>0 independently
predicted malposition of the acetabular
component.
Surgical approach (direct lateral vs
posterolateral), JSW>0, and AD resulted in a
2.00 (1.24-3.22), 1.51 (1.09-2.01) and 1.49
(1.11-1.99) increase in risk for malposition of
the acetabular component, respectively.
Conclusions: Presence of AD, defined as an LCE angle
<25°, is an independent risk factor for
malposition of the acetabular component
during primary THA. Skin approach and
radiological grade of OA were also
independently correlated with malpositioned
cups.
145. High frequency of cystic pseudotumors in large-head metal-on-metal total hip arthroplasty at 5-7 years follow-up.
Mette Holm Hjorth , Niels Egund, Inger Mechlenburg, Stig Storgaard Jakobsen, Kjeld Søballe, Maiken Stilling
Department of Orthopaedics , Aarhus University Hospital ; Department of Radiology, Aarhus University Hospital
Background: Large-head metal-on-metal (MoM) total hip
arthroplasty (THA) has been associated with
pseudotumor formation and high revision
rates.
Purpose / Aim of Study: To investigate the frequency of
pseudotumors, metal-ion concentrations and
radiographic and clinical outcome in patients
with MoM THA.
Materials and Methods: A consecutively included series of 41
patients/49hips (31 males) with a mean age
of 52 (28-68) years, participated in a 5-7-
year follow-up study of their large-headMoM
THA (M2a Magnum, Biomet). Patients were
evaluated with magnetic resonance imaging
(MRI), serum metal-ion concentrations,
conventional radiographs, and clinical
outcome measures of Harris Hip Score (HHS)
and Oxford Hip Score (OHS).
Findings / Results: 18 of 47 hips (38%) had MRI-verified
pseudotumors, all cystic, with a mean
dimension of 1.1 x 2.6 x 0.4 cm. Acetabular
cup anteversion was mean 28+5° in patients
with a pseudotumor and mean 24 +7° in
patients without a pseudotumor (p=0.009).
Serum metal-ion concentrations, acetabular
cup inclination and clinical outcome measures
of HHS and OHS were similar between
patients with and without a pseudotumor.
Conclusions: At 5-7 year after surgery, MRI-verified cystic
pseudotumors were frequently observed in
large-head MoM THA, without relation to
clinical symptoms and metal-ion
concentrations but with relation to cup-
anteversion. The clinical relevance and the
natural history of cystic pseudotumors in
asymptomatic patients remain unknown;
hence, we will continue to monitor these
patients regularly.
146. Radiologic and histologic appearance of metal-bone interphase in failed tibial component in total knee arthroplasty. A retrieval study.
Tue Smith Jørgensen, Thomas Lind, Henrik Schrøder, Eva Balslev
Ortopædkirurgisk afdeling, Herlev hospital; ortopædkirurgisk afdeling, Gentofte Hospital; patolgisk afdeling, Herlev hospital
Background: Little information is available considering lack
of ingrowth of bone into the porous coated
knee prosthesis. Ususally described as
fibrous tissue in the bone-metal interphase.
Our five retrieval cases showed macro-
and microscopic signs of hyaline cartilage in
the tibia bone-metal interphase.
Purpose / Aim of Study: We want to describe the histological findings
in the tibia bone-metal interphase, and
correlate this to the radiologic and
scintigraphic findings in connection with
suspected aseptic loosening especially on
the tibia side.
Materials and Methods: The five patients all underwent primary
knee surgery during the period 2004-
2006 with uncemented knee prosthesis
of porous coated type (PFC). Four with
osteoarthritis and one with rheumatoid
arthritis. They were chosen for
secondary operation because of pain
and suspected loose tibia component. At
revision the resected bone slice was
send for pathological examination. Pre-
and post op. x-rays are measured to
evaluate the amount of primarily resected
bone.
Pubmed Keywords: uncemented, TKA,
failure, cementless, press fit condylar
tibia component, tantalum knee, bone
ingrowth. Bone metal interphase
Findings / Results: In all the samples, which surface turned
against the prosthesis we found hyaline
cartilage-like tissue. No articles were found,
regarding hyaline cartilage in the bone metal
interphase, during our Pubmed search. Only
histological confirmed fibrous tissue were
described.
We discuss some considerations regarding
level of resection, possible diagnostic
features and the radiological appearance.
Conclusions: One of the possible modes of failure of
uncemented knee prosthesis could be the
interference of cartilage formating cells,
occluding the interphase, before the
osseointegration can take place.
In some of the specimens, small areas of
ingrowth around the tibial peg, was
observed.
147. Hip arthroplasty with the Primoris® stem – Bone remodelling around a short femoral neck stem
Janus Duus Christiansen, Lauersen Mogens Berg, Gordon Blunn, Poul Torben Nielsen
Northern Ortopaedic Division, Aalborg University Hospital; , University College London, RNOHT, Stanmore, United Kingdom
Background: Total hip arthroplasty gives immediate
pain relief and restoration of mobility in
patients with end stage osteoarthritis. If
the patient returns for revision and
after two or three revisions bone stock
left for reimplantation will be
compromised. The Primoris ® stem is
a development of earlier conceived
bone-saving prosthesis in order to
preserve bone stock.
Purpose / Aim of Study: This study includes postoperative
changes in BMD in the proximal femur
and evaluation of bone stock
preservation at 1 year follow up (FU) in
patients with the Primoris ® stem.
Materials and Methods: : A prospective cohort study of 52
patients scheduled for surgery with the
femoral neck-preserving Primoris ®
stem was carried out. Patients were
studied with DEXA-scans, RSA-
analysis, Harris hip score, UCLA
activity score, WOMAC, EQ5D health
questionnaire and Oxford Hip scores.
Results from DEXA-scanner were
measured in 3 specific regions of
interest (ROI) - the regions of calcar
(ROC), trochanter minor (ROT) and a
diaphysial reference (ROD).
Postoperative BMD results from day
one, 6 months and 12 months were
analysed.
Findings / Results: 3 patients were excluded, leaving 49
patients for BMD-analysis. A slightly
significant decrease was found at 6
months FU compared to day one in
ROC and ROT. There was no
significant difference at 12 months FU
compared to day one. A non significant
gain of BMD was found at 12 months
FU compared to 6 months FU.
Conclusions: As to bone preservation the results are
encouraging. Later follow up will be
performed to evaluate if the bone stock
remains. If the proximal femoral bone
stock is preserved and diaphysis is not
compromised then the potential for
successful future revision is maximized.
148. Prevalence of kidney dysfunction at elective total hip arthroplasty operations.
Helene Berg-Nielsen, Morten Boye Petersen, Mette Brimnes Damholt, Søren Solgaard
Lægevidenskab, Københavns Universitet; Ortopædkirurgisk afdeling, Gentofte Hospital; Nefrologisk afdeling, Rigshospitalet
Background: Previous studies in other surgical
specialties have shown a clear
correlation between even small increases
in plasma Creatinine (pCr), development
of Acute Kidney Injury (AKI) and
increased long-term mortality.
Purpose / Aim of Study: To investigate pre-operative kidney
function as estimated glomerular
filtration rate (eGFR) and the
occurrence of AKI amongst a population
undergoing elective hip arthroplasty.
Materials and Methods: The study is a single-center,
retrospective, register-based cohort
study including all primary, elective,
total hip replacement surgeries (THA)
carried out in Hørsholm and Gentofte
hospitals from Jan. 2000 to Dec. 2012.
Presence of AKI and eGFR was evaluated
on basis of international KDIGO criteria.
Findings / Results: 5687 operations were performed in 4909
patients. Only the first THA for each
person was considered. Pre-operative pCr
(< 3 months pre operation) could be
obtained for 3328 persons (68 %); 2014
females and 1314 males; age 68,6 ± 10,1
years (mean±SD). In this population
kidney function was moderately to
severely decreased (eGFR < 59 ml/min)
(CKD 3-5) in 11,9 % of the patients.
Both pre- and postoperative pCr (one
value within three days after operation)
could be obtained in 2388 persons (49%
of patients). Development of AKI based
on an increase in pCr was seen in 35
persons (1,5 %) in this population.
Conclusions: Decreased kidney function seems to be
prevalent in an elective orthopedic
population. Data is not sufficient to
evaluate whether AKI is prevalent in
this population, but 1,5 % of the
patients, who could be evaluated, meet
criteria for development of acute kidney
injury. If we are to determine the
impact of AKI in orthopedic patients,
measuring pCr should be part of the
standard postoperative observation.
Further studies are ongoing.
149. Average cyst volume per cyst-patient decreases over a 10-year period after periacetabular osteotomy
Inger Mechlenburg, Jens R. Nyengaard, John Gelineck, Kjeld Søballe
Orthopaedic Research, Aarhus University Hospital; Stereology and Electron Microscopy Laboratory and CSGB , Aarhus University; Department of Radiology, Aarhus University Hospital
Background: Bone cysts in patients with hip
dysplasia are the results of
degeneration or defects of the cartilage
and local elevated stress in the
subchondral bone.
Purpose / Aim of Study: To examine how many patients have
acetabular or femoral head cysts and
investigate whether the volume of
cysts change after PAO.
Materials and Methods: Magnetic resonance imaging (MRI)
was performed in a series of 26
consecutively included patients before
periacetabular osteotomy (PAO) and 1,
2½ and 10 years after. 26 patients had
MRI preoperatively, 25 returned for
MRI at 1 year, 21 at 2½ years and 18
at 10 year follow up. The number of
cysts was noted and the total cyst
volume in each patient was estimated
with a design-unbiased stereology.
The Hip disability and Osteoarthritis
Outcome Score (HOOS) was collected
4 and 10 years after PAO.
Findings / Results: Preoperative, 12 patients had
acetabular or femoral head cysts (22
cysts), 1 year postoperative, 15
patients had cysts (23 cysts), 2½ years
postoperative, 15 patients had cysts
(18 cysts) and 10 years after PAO 9
patients had cyst (9 cysts). Mean total
acetabular cyst volume per cyst-patient
at the time of MRI was: 3.44 + 6.71
cm3 (1.96 + 3.97 cm3) 0.96 + 1.70
cm3 (0.43 + 0.26 cm3) (p=0.04). All
acetabular cysts were located
anterolaterally in the acetabulum
except for one that was posterolateral.
At 4 and 10 years, the mean
subscores for HOOS were Pain 75/79,
Symptoms 75/73, ADL 83/85,
Sport/recreation 63/68 and Quality Of
Life 62/61.
Conclusions: The mean total cyst volume per cyst-
patient decreased significantly over a
10-year period after PAO. We believe
this is a result of decreased local
stress in the subchondral bone after
PAO which also indicates that
redirection of the acetabulum reduces
the risk of progression of osteoarthritis
in the operated hip.