Session 11: Hip
19. November
13:30 - 15:00
Lokale: 01+02
Chairmen: Claus Varnum & Stig S Jakobsen
80. Migration of the uncemented Echo Bi-Metric and Bi-Metric THA stems: a randomized controlled RSA-study involving 62 patients with 24-months follow-up
Karen Dyreborg, Mikkel R. Andersen, Nikolaj Winther, Søren Solgaard, Gunnar Flivik, Michael Mørk Petersen
Rigshospitalet, Department of Orthopaedic Surgery, Copenhagen, Denmark;
Herlev-Gentofte Hospital, Department of Hip and Knee Surgery, Hellerup, Denmark;
Lund University and Skåne University Hospital, Department of Orthopedics, Lund,
Sweden
Background: Despite the good results after total hip arthroplasty
(THA), new implants are continuously being
developed to improve the durability. The Echo Bi-
Metric (EBM) THA stem is the successor to the Bi-
Metric (BM) THA stem. The EBM stem includes
many of the features of the BM stem, but minor
changes in the design might improve the clinical
performance.
Aim: We compared the migration behavior with
radiostereometric analysis (RSA) of the EBM stem
and the BM stem at 24 months and evaluated the
clinical outcome.
Materials and Methods: We randomized 62 patients with osteoarthritis (mean
age=64 years, Female/Male=28/34) scheduled for
an uncemented THA to receive either an EBM or a
BM THA stem.
We performed RSA within 1 week after surgery and
at 3, 6, 12, and 24 months. The clinical outcome was
evaluated using Harris Hip Score (HHS) and Oxford
Hip Score (OHS).
Results: At 24 months, we found no statistically significant
differences in migration between the two implants.
During the first 3 months both the EBM and the BM
stems showed visible subsidence (-2.5 mm and -2.2
mm respectively), and retroversion (2.5° and 2.2°
respectively), but after 3 months this stabilized. The
expected increase in HHS and OHS was similar
between the groups.
Interpretation / Conclusion: The EBM stem shows a migration at 24 months not
different from the BM stem, and both stems display
satisfying clinical results.
81. Patient-reported outcome after dislocation of primary total hip arthroplasties – a cross-sectional matched case-control study derived from the Danish Hip Arthroplasty Register
Lars Lykke Hermansen, Bjarke Viberg, Søren Overgaard
Department of Orthopaedics, Hospital of South West Jutland, Esbjerg,
and The Orthopaedic Research Unit, Department of Orthopaedic
Surgery and Traumatology, Odense University Hospital, Odense;
Department of Orthopaedic Surgery and Traumatology, Odense
University Hospital, Odense and Department of Orthopedic Surgery and
Traumatology, Lillebaelt Hospital, University hospital of Southern
Denmark; Department of Orthopedic Surgery and Traumatology,
Bispebjerg Hospital og Institute of Clinical Medicine, Copenhagen
University
Background: It is well-known that there is substantial risk
of re-dislocation and eventually revision
after the first dislocation following primary
THA, but knowledge about patient-reported
outcomes (PRO) after dislocation and
closed reduction is lacking.
Aim: Our aim was to report on health- and hip-
related quality of life (QoL) in patients with
dislocation following primary THA due to
osteoarthritis.
Materials and Methods: We conducted a cross-sectional,
matched case-control study involving
patients registered in the Danish Hip
Arthroplasty Register between 2010 and
2014. Dislocations were captured in the
Danish National Patient Register using a
validated algorithm. We matched
patients with dislocation 1:2 upon age,
sex, date and hospital of primary surgery
to patients without dislocation. They
received two PRO questionnaires (EQ-
5D, HOOS) and three patient satisfaction
items. Results are presented as means
with 95% confidence intervals and
analyzed with multiple linear regression.
Results: We identified 1010 living patients with
dislocation. The response rate was
70.1%. Mean follow-up was 7.2 years
from index surgery and 4.9 years from
the latest dislocation. Patients without
dislocation reported a higher EQ-5D VAS
score of 75.6 (74.5-76.7) compared to
67.8 (65.9-69.7) in the dislocation group
(p<0.01). Regarding hip-related QoL,
patients with dislocation reported a lower
HOOS-QoL domain score of 62.8 (60.2-
65.4) compared to 82.9 (81.7-84.1) in
the control group (p<0.01). Even after
five years from the latest dislocation, the
HOOS-QoL score was still low,
demonstrated by 65.6 (62.0-69.2) points.
The other HOOS domains were
consistently 8-10 points worse after
dislocation. Regarding satisfaction, only
59% reported either an “excellent” or a
“very good” overall result after
experiencing dislocations, as opposed to
85% for the controls.
Interpretation / Conclusion: This is the first national case-control study
on PRO after hip dislocation. The study
showed that both health- and hip-related
QoL is markedly and persistently reduced
compared to a control group even 2-5 years
after the latest dislocation. The most
important aspect must be to avoid the first
episode of dislocation, since the full
relieving potential for this THA is never
achieved.
82. Revision risk of total hip arthroplasty with vitamin E doped liners: Results from The Danish Hip Arthroplasty Register
Kristian Kjærgaard, Claus Varnum, Ming Ding, Søren Overgaard
Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, J.B.Winsløws Vej 4, DK-5000 Odense C. Department of Clinical Research, University of Southern Denmark, Campusvej 55, DK-5230 Odense S;
Department of Orthopaedic Surgery, Lillebaelt Hospital – Vejle, Beriderbakken 4, DK-7100 Vejle. Department of Regional Health Research, University of Southern Denmark, Winsløwparken 19,3, DK-5000 Odense C;
Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, J.B.Winsløws Vej 4, DK-5000 Odense C. Department of Clinical Research, University of Southern Denmark, Campusvej 55, DK-5230 Odense S;
Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, J.B.Winsløws Vej 4, DK-5000 Odense C. Department of Clinical Research, University of Southern Denmark, Campusvej 55, DK-5230 Odense S. Bispebjerg og Frederiksberg Hospital, Ortopædkirurgisk afdeling M, Nielsine Nielsens Vej 5, opgang 6, 2. sal, 2400 København NV. Københavns Universitet, Sundhedsvidenskabelige Fakultet, Institut for Klinisk Medicin
Background: The main long-term revision cause for total hip arthroplasty (THA) is aseptic loosening. This is associated with polyethylene wear and a lower wear would, in theory, reduce the rate of revision due to aseptic loosening. Vitamin E doped polyethylene liners have been designed to reduce wear, but the material is rather new and needs post marked surveillance analysis in large register studies.
Aim: The aim of this nationwide population-based study was to investigate 1) the risk of polyethylene-related endpoints (aseptic loosening, wear, granuloma, or osteolysis) from 12 months after THA with vitamin E-doped polyethylene (VEPE) liners compared to THA with cross-linked annealed or remelted polyethylene (XLPE) liners and 2) the risk of any and specific revision causes.
Materials and Methods: We included THAs from The Danish Hip Arthroplasty Register from January 1, 2008 to June 30, 2019, with uncemented cup, VEPE or XLPE liner, and metal or ceramic head. The outcome was polyethylene-related endpoints from 12 months and onwards, and further outcomes were any and specific revision causes. Risk of revision was estimated using Cox regression.
Results: A total of 110,803 THAs were assessed for eligibility and 63,892 THAs (55,230 patients) were included in the study, 5,885 (9.2%) THAs with a VEPE liner and 58,007 (91.8%) with a XLPE liner. Median observation time was 5.35 (inter-quartile range (IQR) [3.62, 7.09]) years for VEPE and 4.78 (IQR [2.64, 7.68]) for XLPE.
We found a lower risk of revision for polyethylene-related endpoints from 12 months for VEPE compared to XLPE (hazard ratio (HR) 0.51 [0.31, 0.84]). THAs with VEPE liners were associated with increased risk of any revision within the first 3 months (HR 1.57 [1.33, 1.86]), revision recorded as aseptic loosening within 3 months (4.15 [2.19, 7.87]), fracture within 3 months (HR 2.58 [1.99, 3.34]), and other revision at any time (1.35 [1.00, 1.81]).
Interpretation / Conclusion: VEPE liners had a lower revision rate due to polyethylene-related endpoints from 12 months compared to XLPE liners. No difference in other specific reasons was shown. Regarding safety, we found one cracked liner in VEPE while thirteen cracked liners were reported for XLPE.
83. Outcomes of surgical hip abductor tendon repair with one-year follow-up. Our initial experience.
Marie Bagger Bohn, Bent Lund, Kasper Spoorendonk, Jeppe Lange
H-HiP, Department of Orthopedic Surgery, Horsens Regional Hospital, 8700 Horsens,
Denmark, Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark;
H-HiP, Department of Orthopedic Surgery, Horsens Regional Hospital, 8700 Horsens,
Denmark;H-Hip, Department of Physio and Occupational Therapy, Horsens Regional
Hospital, Denmark; H-HiP, Department of Orthopedic Surgery, Horsens Regional
Hospital, 8700 Horsens, Denmark, Department of Clinical Medicine, Aarhus University,
8200 Aarhus N, Denmark
Background: Awareness of Gluteus medius (GM) and/or
minimus tendon tears as the cause of lateral hip
pain (LHP) has been growing over the past two
decades. It is estimated that GM tears may be
present in as many as 25% of late middle-aged
women and 10% of middle-aged men. Tears that
impart significant functional impairment to
patients and may be a source of debilitating and
chronic LHP. Unfortunately, these tears are often
misdiagnosed and, thus, treated insufficiently. In
recent years, surgical repair has shown
promising results.
Aim: To report one-year outcomes of our initial 40 cases
of surgical repair of GM tendon tears.
Materials and Methods: Data were prospectively collected between
September 2017 and October 2020. Inclusion
criteria for the study were patients undergoing
surgical GM repair who had completed a one-
year follow-up. MRI was pre-operatively used to
visualize the GM tears and select patients
deemed suitable for surgery. Pre- and 12-months
post-operative testing included pain (at rest,
during activity and worst pain (NRS 0-10)),
patient reported outcome measures
(Copenhagen hip and groin score (HAGOS),
Oxford Hip score (OHS), EQ-VAS and Global
rating of Change (GROC)), and maximal
voluntary isometric contraction of hip abduction
(MVC) measured with a handheld dynamometer.
Results: The cohort included 40 patients (36 women) with a
median age of 55 years (range 18-81). From pre- to
12-months post-operative, pain at rest, during
activity and worst pain decreased from 4.7 to 1.6,
6.3 to 2.5, and 8.6 to 4.5 (p>0.001), respectively. All
HAGOS sub scores, OHS and EQ-VAS improved
(HAGOS; pain: 35 to 67, Symptom: 43 to 71, ADL:
34 to 65, Sport/Rec: 21 to 53, PA: 16 to 44 , QOL:
23 to 52 (p>0.001), OHS; 22 to 33 (p>0.001) and
EQ-VAS: 61 to 72 (p=0.0107)). At follow-up the
success rate of GROC (”moderately better” to ”very
much better”) was 61.1%. MVC of the operated and
non-operated hip increased by 0.09 Nm/kg (95% CI
0.007;0.17) and 0.03 Nm/kg (95%CI -0.04;0.11).
Interpretation / Conclusion: This study indicates that surgical repair may be an
effective treatment of MRI verified gluteus medius
tears. At one-year follow-up, the patients experience
less pain, and subjective outcome measures and hip
abductor strength improve.
84. Does choice of bearings influence the survival of cementless stemmed total hip arthroplasty in the patient between 20 and 54 years? A comparison of metal-on-metal, ceramic-on-ceramic and metal-on-highly-crosslinked-polyethylene bearings from the NARA
Rasmus Tyrsted Mikkelsen, Søren Overgaard, Alma Becic Pedersen, Johan Kärrholm, Ola Rolfson, Anne Marie Fenstad, Ove Furnes, Geir Hallan, Keijo Mäkelä, Antti Eskelinen, Claus Varnum
Rasmus Tyrsted Mikkelsen
Department of Orthopedic Surgery, Lillebaelt Hospital - Vejle, University
Hospital of Southern Denmark, Denmark; Department of Regional Health
Research, Faculty of Health Science, University of Southern Denmark
Søren Overgaard
Department of Orthopaedic Surgery and Traumatology, Copenhagen
University Hospital, Bispebjerg, Denmark; University of Copenhagen,
Department of Clinical Medicine, Faculty of Health and Medical Sciences,
Denmark; The Danish Hip Arthroplasty Register; Department of Clinical
Research, University of Southern Denmark; Department of Orthopaedic
Surgery and Traumatology, Odense University Hospital
Alma Becic Pedersen
Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus,
Denmark
Johan Kärrholm
Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska
Academy, University of Gothenburg, Gothenburg, Sweden; The Swedish
Arthroplasty Register, Gothenburg, Sweden
Ola Rolfson
Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska
Academy, University of Gothenburg, Gothenburg, Sweden; The Swedish
Arthroplasty Register, Gothenburg, Sweden
Anne Marie Fenstad
The Norwegian Arthroplasty Register, Department of Orthopedic Surgery,
Haukeland University Hospital, Bergen, Norway
Ove Furnes
Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway; The
Norwegian Arthroplasty Register, Department of Orthopedic Surgery,
Haukeland University Hospital, Bergen, Norway
Geir Hallan
Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway; The
Norwegian Arthroplasty Register, Department of Orthopedic Surgery,
Haukeland University Hospital, Bergen, Norway
Keijo Mäkelä
Department of Orthopaedics and Traumatology, Turku University Hospital,
Turku; The Finnish Arthroplasty Registry, Helsinki, Finland
Antti Eskelinen
The Finnish Arthroplasty Registry, Helsinki, Finland; Coxa Hospital for Joint
Replacement, Tampere, Finland
Claus Varnum
Department of Orthopedic Surgery, Lillebaelt Hospital - Vejle, University
Hospital of Southern Denmark, Denmark; Department of Regional Health
Research, Faculty of Health Science, University of Southern Denmark; The
Danish Hip Arthroplasty Register
Background: Young patients risk undergoing multiple
revisions of their total hip arthroplasty (THA)
leading to poorer clinical outcome. Different
bearings have been introduced to improve the
survival of the THA. However, long-term results
of these bearings in young patients are
unknown.
Aim: Our aim was to compare the survival and risk
of revision of primary stemmed cementless
THA with metal-on-metal (MoM) and ceramic-
on-ceramic (CoC) to that of metal-on-highly-
crosslinked-polyethylene (MoXLP) bearings in
patients between 20-54 years with primary
osteoarthritis or childhood hip disorders.
Materials and Methods: The study population was identified from
the Nordic Arthroplasty Register
Association dataset and consisted of 2,246
MoM, 4,227 CoC and 10,433 MoXLP THA
operated between 1995-2017. We used the
Kaplan-Meier estimator for calculation of
THA survivorship and Cox regression to
estimate the hazard ratio (HR) of revision
(including 95% confidence intervals) due to
any and specific causes adjusted for sex,
age, diagnosis, year of primary surgery and
femoral head size. MoXLP was used as
reference. The hazard ratios were given in
0-2, 2-7 and 7-15 years to meet the
assumption of proportional hazards.
Results: The median follow-up was 10.3 years for
MoM, 6.6 years for CoC and 4.8 years for
MoXLP. 15 years postoperatively the
Kaplan-Meier survival estimates were 80%
(78-83%) for MoM, 92% (91-93%) for CoC
and 94% (93-95%) for MoXLP bearings.
The 0-2, 2-7 and 7-15 years adjusted HRs
of revision by any cause were 1.4 (0.9-2.3),
3.3 (2.1-5.1) and 4.5 (2.3-8.8) for MoM and
1.1 (0.8-1.4), 1.0 (0.7-1.4) and 2.3 (1.2-4.3)
for CoC bearings. After 7-15 years follow-
up, the unadjusted cause specific HR of
revision due to aseptic loosening was 6.4
(1.5-28) for MoM and 4.2 (0.9-20) for CoC
THA. MoM and CoC had a 7-15 years
adjusted HR of revision due to ‘other’
causes of 6.3 (2.1-19) and 2.1 (0.8-6.0).
Interpretation / Conclusion: For patient between 20-54 years receiving a
primary stemmed cementless THA MoXLP
bearings have better survival than MoM and
CoC bearings, mainly because of lower risk of
revision due to aseptic loosening and ‘other’
causes.
85. No difference for changes in BMD between two different cementless hip stem designs 2 years after THA
Karen Dyreborg, Søren Solgaard, Michael Skettrup, Michael Mørk Petersen
Rigshospitalet, Department of Orthopedic Surgery; Herlev-Gentofte University Hospital,
Department of Hip and Knee Surgery
Background: This study evaluates how 2 different total hip
arthroplasty (THA) stems compares regarding
adaptive bone remodelling. The stems are both
proximally porous coated, aiming for proximal
fixation, but with different dispersal of the coating.
They are also differently designed regarding the
distal tip of the stem.
Aim: We aimed to investigate if there is a difference in
periprosthetic adaptive bone remodelling between
two different designs.
Materials and Methods: From February 2016 to September 2017, we
randomised 62 patients, 1:1 (mean age=64 years,
Female/Male=28/34), scheduled for an uncemented
THA to receive either an EBM or a BM THA stem.
We performed dual-energy x-ray absorptiometry
(DEXA) scans within a week after surgery and at 3,
6, 12 and 24 months with measurements of bone
mineral density (BMD) in the 7 Gruen zones (region
of interest (ROI) 1-7). Additionally, Oxford Hip Score
and Harris Hip Score were collected at 6, 12 and 24
months.
Results: We found a decrease in BMD between the
postoperative and the 24-months values in all ROIs
for both stems. The greatest decrease over time was
seen for both groups in the ROI1 (BM =-8.4%,
p=0.044, and EBM=-6.5%, p=0.001) and ROI7 (BM
=-7%, p=0.005, and EBM=-8.6%, p<0.0005).
We found a tendency in ROI2-4 of a higher degree
of bone loss in the EBM group. However, this
difference only continued beyond 6 months in ROI4
(24 months: BM=-1.2% and EBM =-2.8%, p=0.001).
Interpretation / Conclusion: The stems show similar adaptive bone remodelling
and are clinically performing well
86. Risk factors for dislocation and re-revision after first-time revision total hip arthroplasty due to recurrent dislocation – a study from the Danish Hip Arthroplasty Register
Lars Lykke Hermansen, Bjarke Viberg, Søren Overgaard
Department of Orthopaedics, Hospital of South West Jutland, Esbjerg, and
The Orthopaedic Research Unit, Department of Orthopaedic Surgery and
Traumatology, Odense University Hospital, Odense; Department of
Orthopaedic Surgery and Traumatology, Odense University Hospital,
Odense and Department of Orthopedic Surgery and Traumatology,
Lillebaelt Hospital, University hospital of Southern Denmark; Department
of Orthopedic Surgery and Traumatology, Bispebjerg Hospital og Institute
of Clinical Medicine, Copenhagen University
Background: Persistent instability after hip revision due to
dislocation is a serious problem. In order to
lower the risk of this complication, it is
essential to identify risk factors.
Aim: Our aim was to analyze surgery- (liner type,
extent of revision, head size) and patient-
(age, sex, Charlson comorbidity index
(CCI)) related risk factors for both new
dislocation and re-revision of any cause
following a first-time revised hip due to
dislocation.
Materials and Methods: We included patients with a primary THA
due to osteoarthritis and a first-time
revision due to dislocation registered in
the Danish Hip Arthroplasty Register
(DHR) from 1996-2016. Patients were
followed from the day of the first revision
to either Dec. 2018, re-revision, or death.
We identified dislocations in the Danish
National Patient Register based on a
validated method and re-revisions in the
DHR. Risk factors were analyzed by a
Fine-Gray multiple regression analysis
adjusting for the competing risk of death.
Results are presented as sub-distribution
hazard ratios (sHR) with 95% confidence
intervals.
Results: We identified 1,678 first-time revisions
due to dislocation and 22.4% of these
had a new dislocation. 19.8% were re-
revised for any reason. Median follow-up
was 5.3 years.
For new dislocations, the sHR was 0,36
(0.27-0.48) for those who had a
constrained liner (CL) during revision
and 0.21 (0.08-0.58) for dual mobility
cups (DMC) meaning a lower risk of
dislocations compared to regular liners.
Changing only the head/liner increased
the risk of dislocation (sHR=2.65 (2.05-
3.42)) compared to full cup revisions.
Age, sex, CCI, and head size was not
significant risk factors for new
dislocations.
Regarding risk of new re-revision,
changing only head/liner resulted in an
increased risk of re-revision (sHR=1.73
(1.34-2.23)). Patients <65 years had
increased risk of re-revision compared to
65-75 years (sHR=1.36 (1.05-1.77)).
Sex, CCI, head size and liner type were
not significantly associated with re-
revisions.
Interpretation / Conclusion: Patients revised with a DMC and CL were
associated with a lower risk of dislocation
after a first-time revision but not re-revision
whereas only changing the head/liner was
associated with higher risk of dislocation
and re-revision.
87. The impact of socioeconomic status on the 30- and 90-day risk of infections after a total hip arthroplasty
Nina M. Edwards, Claus Varnum, Søren Overgaard, Rob G. H. H. Nelissen, Alma B. Pedersen
Department of Clinical Epidemiology, Aarhus University Hospital, Denmark;
Department of Orthopaedic Surgery, Lillebaelt Hospital - Vejle, Denmark and Department of Regional Health Research, University of Southern Denmark, Denmark;
Danish Hip Arthroplasty Register;
Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Denmark, Department of Clinical Research, University of Southern Denmark, Denmark;
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
Background: In orthopaedic surgery, the quality of care and outcomes after surgery are correlated to socioeconomic status (SES). However, previous research concerning infection is limited by assessing SES only by a single marker, no distinction between infection causes, or area-based SES measurements.
Aim: We examined whether SES is associated with the risk of hospitalization due to infections after total hip arthroplasty (THA) within 30 and 90 days.
Materials and Methods: We obtained individual-based information on SES markers (cohabitation, education, income, and liquid assets) on 103,901 THA patients from Danish health registers (year 1995-2017). The outcome was readmission due to any infection, pneumonia, urinary tract infection (UTI), or periprosthetic joint infection (PJI). We calculated the cumulative incidences with death as competing risk, and we used the pseudo-observation method and generalized linear regression to estimate relative risks (RR) with 95 % confidence intervals (CI).
Results: The cumulative incidence of any infection at 90 days was highest among patients who lived alone (1.5% (CI 1.3-1.6)), had the lowest education (1.1% (CI 1.0-1.6)), had the lowest income (1.5% (CI 1.3-1.6)), and had lowest liquid assets (1.3% (CI 1.1-1.4)).
The RRs for any infection within the first 30 days were 1.5 (CI 1.3-1.7) for patients living alone vs. cohabiting, 1.3 (CI 1.1-1.6) for medium income vs. high income, and 1.6 (CI 1.4-1.8) for low liquid assets vs. high liquid assets. Education was not associated with the risk of any infection, however, the RR for pneumonia was 8.0 (CI 2.2-30.0) for low education vs. high education. The RR for PJI were 1.2 (0.6-2.3) for patients living alone vs. cohabiting, 1.6 (0.8-3.3) for low liquid assets vs. high liquid assets. The same trends were seen within the first 90 days.
Interpretation / Conclusion: We found that living alone, low education, low income, and low liquid assets were all associated with higher risks of infections within the first 30 and 90 days after THA. Our findings highlight the socioeconomic disadvantage as a risk factor for developing infection after THA, emphasizing the importance of policy-, patient,- and surgeon practice when addressing inequalities in THA outcome.
88. Dislocation rate of Dual Mobility Cup in 2711 THAs with up to ten years follow-up
Katrine Hvidt, , Katrine Væsel Wade, Niels Harry Krarup, Marianne Toft Vestermark
Katrine Hvidt; Department of Orthopaedics, Aarhus University Hospital
Katrine Væsel Wade; Department of Orthopaedics, Viborg Regional Hospital
Marianne Toft Vestermark; Department of Orthopaedics, Viborg Regional Hospital
Niels Harry Krarup; Department of Orthopaedics, Viborg Regional Hospital
Background: Dislocation is a well-known complication after total
hip arthroplasty (THA). The dual mobility cup (DMC)
has shown promising results in lowering the
dislocation rate compared to conventional cups, but
not many studies on long-term dislocation rate of
DMC in a large cohort are available.
Aim: To determine the dislocation rate of DMC in primary
THAs in a large cohort with up to ten years follow-
up. Further, to elucidate factors that might affect the
dislocation rate.
Materials and Methods: The Danish Hip Arthroplasty Registry (DHR) was
used to identify primary THAs with DMC inserted at
Viborg Regional Hospital since January 2001. 2711
were included, 1874 Saturne® cups and 837
Avantage™ cups. Events of dislocations, revisions
and patient deaths were retrospectively identified by
review of medical files. Information for subgroup
analysis was collected from DHR.
Results: The two-year dislocation rate for DMC was 2,21%,
ten-year dislocation rate was 2,79%. The risk of
dislocation was lowest in patients who had THA with
DMC due to primary arthrosis with a ten-year
dislocation rate of 1,4% and highest in patients
treated for a displaced collum femoris fracture with a
ten-year dislocation rate on 4,00%. No significant
difference in risk of dislocation was found when
comparing Saturne® and Avantage™ cups.
Interpretation / Conclusion: Our findings indicate a lower dislocation rate of
DMC compared to conventional cups, especially in
regard to long-term risk. Further studies on
prosthesis survival of DMC are needed.
89. Socioeconomic status and use of analgesic drugs before and after primary total hip arthroplasty: A population based cohort on 103,209 patient undergoing primary total hip arthroplasty during 1996-2018
André Nis Klenø, Martin Bækgaard Stisen, Nina Mckinnon Edwards, Inger Mechlenburg, Alma Becic Pedersen
Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N
Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark
Department of Clinical Medicine, Aarhus University, Denmark
Background: Hip osteoarthritis (OA) approximately affects 11% of
people globally. When pharmacological and non-
pharmacological treatment fail to provide adequate
pain relief, total hip arthroplasty (THA) is
recommended. Although THA is an effective and
common procedure, persistent pain and use of
analgesics up to two years after THA surgery are
common.
Aim: We examined the trends in the utilization of
analgesics before and after THA, overall, and in
relation to markers of socioeconomic status (SES) in
a population based cohort.
Materials and Methods: We used the Danish Hip Arthroplasty Registry to
identify 103,209 patients who underwent THA
between 1996 and 2018. Data on medication and
SES markers were obtained from Danish medical
databases. Proportions of redeemed prescriptions
for analgesics with 95% confidence intervals
(95%CI) were calculated for 4 quartiles before and 4
quartiles after THA for the entire THA population,
and by three SES markers (education, cohabiting
status and wealth).
Results: Overall, the proportion of analgesic use was 41.8%
(95%CI 40.5;42.1) at 9-12 months and 58.8%
(95%CI 58.5;59.1) at 0-3 months before THA. The
proportion of analgesics reached its highest at
64.0% (95%CI 63.7;64.3) 0-3 months after THA, but
declined to 27.0% (95%CI 26.8;27.3) at 9-12
months after THA. Low education, living alone and
having low wealth (low SES) were associated with
higher proportions of analgesic use both before and
after THA. Use of analgesics decreased after THA
regardless of SES, but the decrease was less
pronounced among patients with low SES.
Interpretation / Conclusion: The use of analgesics decreased 9-12 months after
THA, but remained relatively high. Our results
suggest that clinicians should focus in the larger
extent on patients with low SES when phasing out of
opioid treatment and planning rehabilitation.