Risk for Second Revision in Patients With Cemented Versus Non-cemented Acetabular Component at Primary THA. A National Cohort Study From DHR
Conditions: Total Hip Arthroplasty (THA), Revision Hip Arthroplasty
Sponsor: Bispebjerg Hospital

Version 1 
          30.08.2024 
 
 
STUDY PROTOCOL  
 
Risk for second revision in patients with cemented versus non-cemented acetabular component at 
primary THA. A national cohort study from DHR 
Mohammed Alarim, MD1; Saber M. Aljuboori, MD, PhD fellow2,3; Afrim Iljazi, MD; Michael Mørk Petersen, 
Professor, MD, DMSc3,4; Søren Overgaard, MD, DMSc, Professor2,3 
 
 
1. Department of Orthopedic surgery and traumatology, Hvidovre Hospital, Copenhagen, Denmark, 2. 
Department of Orthopedic Surgery and Traumatology, Copenhagen University Hospital, Bispebjerg and 
Frederiksberg, Copenhagen, Denmark; 3. University of Copenhagen, Department of Clinical Medicine, Faculty 
of Health and Medical Sciences; 4. Department of orthopedic surgery, Rigshospitalet 
 
  
Corresponding author: 
Mohammed Alarim 
MD 
Department of Orthopedic surgery  
Hvidovre hospital  
e-mail:    
               mohammed.alarim@regionh.dk  
              dr.mohammed.3amir@gmail.com 
                
 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 2 
 
Contents 
Summary / Abstract .............................................................................................. Error! Bookmark not defined. 
Background ........................................................................................................................................................ 3 
Methods ............................................................................................................................................................. 4 
Study design ............................................................................................................................................. 4 
Data sources and linkage .......................................................................................................................... 4 
Study population ...................................................................................................................................... 4 
Outcomes ................................................................................................................................................. 5 
Statistical analysis .................................................................................................................................... 8 
Ethical considerations ...................................................................................................................................... 10 
Clinical implications ......................................................................................................................................... 10 
Reporting and trial registration ........................................................................................................................ 11 
Dissemination policy ........................................................................................................................................ 11 
Budget .............................................................................................................................................................. 11 
Funding ............................................................................................................................................................ 11 
Time schedule .................................................................................................................................................. 11 
References ....................................................................................................................................................... 12 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 3 
 
 
Summary/Abstract 
 
Background 
Total hip arthroplasty (THA) is considered to be one of the most successful operations performed in orthopedic 
surgery and the treatment of choice for end-stage osteoarthritis of the hip (1). The frequency of revision 
surgery for total hip joint arthroplasty continues to increase worldwide (2).  Generally, the longevity of revision 
THA is less than that of primary THA (3) . Although the optimal component fixation method in primary THA is 
still debated, several studies have shown increased use of the cementless technique in most parts of the world 
(4–6). The use of cementless technology in THA initially gained popularity as complications such as aseptic 
loosening and “cement disease” began to surface with the use of first-generation cement techniques (7–9). 
Cementless acetabular components have achieved widespread acceptance in THA as a result of their improved 
and reliable long-term results(10). Primary stability is achieved through press-fit fixation that requires 1–3 mm 
under-reaming of the acetabular cavity and forceful impaction.  Studies have shown slightly higher risk of 
revision in uncemented acetabular components compared to those cemented (11). We believe that the 
differences in the fixation method during the primary operation significantly affects the surgical techniques 
implemented in the first revision of each group and by that influencing the risk of second revision. This was 
shown before in cemented vs. uncemented stem, but no study has to our knowledge reported the same 
concerning acetabular components (12). In previous studies comparing the risk of revision in patients 
undergoing THA with cemented and hybrid fixation techniques (where the cup component is non-cemented), 
the hybrid technique was associated with a higher risk of revision for any reason compared to the cemented 
technique, regardless of the patient's sex and age (11). The justification for this difference in revision rates can 
be the use of cement in cup fixation. This suggests that the use of cement in cup fixation may provide certain 
advantages, such as increased stability or longevity, which could potentially lead to a lower risk of revision 
compared to non-cemented cup fixation. Therefore, further research and clinical considerations are necessary 
to fully understand the implications of cup fixation techniques in risk of THA revision. We expect that the result 
from this study would help in the choice of fixation technique by shedding light on an under investigated 
outcome concerning the complications associated with fixation technique. 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 4 
 
Objective 
The objectives of this study are to investigate the risk of second revision of the cup alone or any component 
after first cup revision following cemented or non-cemented cup in the primary THA.  
Methods 
Study design 
The current study is a nationwide register-based cohort study that utilizes prospectively collected data from 
the Danish Hip Arthroplasty Register (DHR) and the Danish National Patient Registry (DNPR). The study will 
follow the reporting of studies Conducted using Observational Routinely collected health Data (RECORD) 
guidelines (13). We will include patients who have undergone THA at both public and private hospitals from 
January, 1st ,1995, to December 31st, 2020, to ensure a minimum follow-up of 1 year. Patients will be followed 
from the date of the first revision and until the first of the following: Implant removal of the acetabular 
component, death, emigration, until the date where there is a minimum of 100 patients left in the risk set for 
each group, or until December 31st, 2021. 
 
Data sources and linkage  
We will use data from the DHR and the DNPR. The DHR was founded in 1995 prospectively collects data on all 
THAs in public and private hospitals and their subsequent revisions in Denmark. Reporting from both public 
and private hospitals is mandatory(14). As of 2021, the DHR has a reporting rate of 97% for primary THAs and 
95% for revisions (14). The DNPR is a national administrative database that registers all hospital contacts, 
including discharge diagnoses (15). All Danish residents have a unique 10-digit Civil Personal Register (CPR) 
number in the Danish Civil Registration System (DCRS) and this number enables to cross-link inhabitants in 
Denmark across different databases and to be traced until death or emigration. 
 
Study population 
We will include all THAs reported to the DHR that meet the following eligibility criteria:  
Inclusion criteria 
▪ 
Primary osteoarthritis as the indication for the primary THA. 
▪ 
Has experienced a first revision with exchange of the liner, femoral head and/or acetabular 
component either with or without exchange of the femoral component.   
▪ 
Femoral with a size of 28mm, 32mm or 36mm after the first revision 
▪ 
Surgery with the posterior approach.  

 
 
 
 Cementation of cup and the risk of second revision: 5 
 
 
Exclusion criteria 
▪ 
Isolated revision of the femoral component.  
▪ 
Constrained liner.  
▪ 
Metal-on-metal implant. 
 
 
Outcomes 
The following outcomes have been defined for the current study: 
Primary outcome 
The risk of undergoing a second revision of the acetabular component after having first revision with 
exchange of the acetabular component.  
Revision is defined as any surgical procedure that involves skin incision in the ipsilateral hip joint due to 
acetabular component failure as reported in the DHR or having one of the following NOMESCO (Nordic 
Medico-Statistical Committee) Classification of Surgical Procedures codes in the DNPR:  
- 
Secondary insertion of non-cemented total hip alloplastic in hip joint (KNFC2) 
- 
Secondary insertion of proximal component in non-cemented partial hip alloplastic (KNFC01) 
- 
Secondary insertion of hybrid hip alloplastic in hip joint (KNFC3)   
- 
Secondary insertion of cemented total hip alloplastic in hip joint (KNFC4)   
- 
Secondary insertion of non-cemented proximal part alloplastic (acetabular component) in hip joint 
(KNFC10) 
- 
Secondary insertion of cemented proximal part alloplastic (acetabular component) in hip joint 
(KNFC11) 
- 
Secondary insertion of non-cemented proximal part alloplastic (acetabular component) in hip joint 
(KNFC21) 
- 
Secondary insertion of hybrid proximal part alloplastic (acetabular component) in hip joint (KNFC31) 
- 
Secondary insertion of cemented total alloplastic (acetabular component) in hip joint (KNFC41) 
- 
Secondary insertion of non-cemented total alloplastic in hip joint (KNFC29)  
- 
Secondary insertion of non- cemented both components in total alloplastic in hip joint (KNFC20) 
- 
 Secondary insertion of cemented both components in total alloplastic hip joint (KNFC40) 
- 
Secondary insertion of cemented total alloplastic hip joint without specification (KNFC49)  
 
 

 
 
 
 Cementation of cup and the risk of second revision: 6 
 
Secondary outcome 
1. All cause revision Defined as any surgical procedure that involves skin incision in the ipsilateral hip joint 
with one of the following NOMESCO codes: 
- 
Secondary insertion of distal component of non-cemented partial hip alloplastic (KNFC02) 
- 
Secondary insertion of both components of non-cemented total hip alloplastic (KNFC20) 
- 
Secondary insertion of distal component of non-cemented total hip alloplastic (KNFC22) 
- 
Secondary insertion of another component of non-cemented total hip alloplastic (KNFC23) 
- 
Secondary insertion of distal component of hybrid total hip alloplastic (KNFC32) 
- 
Secondary insertion of another component of hybrid total hip alloplastic (KNFC33) 
- 
Secondary insertion of distal component of cemented total hip alloplastic (KNFC42) 
- 
Secondary insertion of another component of cemented total hip alloplastic (KNFC43) 
- 
Secondary insertion of interponert prosthetic in the hip (KNFC59) 
- 
Secondary insertion of prosthetic join in the hip without specification (KNFC99) 
- 
Exploration of soft tissue in hip or thigh (KNFA0) 
- 
Exploration of hip joint (KNFA1) 
- 
Tissue or joint biopsy in hip or thigh (KNFA2) 
- 
Resection arthroplasty in hip joint (KNFG09) 
- 
Incision and revision due to infection in hip joint (KNFS19) 
- 
Incision and revision due to infection in hip joint with applying of drugs/medicine (KNFS49) 
- 
Another operation for infection in ligament, joint and bone in hip and femur (NFS99) 
- 
Reoperation due to ruptured wound after operation in hip or thigh (KNFW49) 
- 
Reoperation due to deep infection after operation in hip or thigh (KNFW69) 
- 
Reoperation due to deep bleeding after operation in hip or thigh (KNFW89) 
- 
Another reoperation after operation in hip joint or thigh (KNFW99) 
- 
Reoperation due to superficial infection in hip or femur (KNFW59) 
- 
Reoperation due to superficial bleeding in hip or femur (KNFW79) 
- 
Removal of total prosthetic or a part of it from hip (NFU1Y) 
- 
Removal of implant In relation to infection treatment in hip or femur (NFU89) 
- 
Removal of another implant from hip or femur (NFU99) 
- 
Another operation in hip or femur, not specified (NFT 99) 
- 
 Reimplantation in femur or hip (NFP29/NFP) 
All other unspecified causes indicated in the codes will be directed to the DHR for clarification on whether it 
is a cup or stem revision, or to specify which component is being revised.  

 
 
 
 Cementation of cup and the risk of second revision: 7 
 
 
 
Variables  
We will gather the following variables from databases (DHR, DNPR) 
DHR 
▪ 
Age. 
▪ 
Gender. 
▪ 
Laterality of surgery. 
▪ 
Indication for primary surgery 
▪ 
Indication for first revision. 
▪ 
Fixation technique. 
▪ 
Date of surgery 
▪ 
Type of surgery: primary, revision, re-revision.  
▪ 
Acetabular bone loss after 1. Revision. 
▪ 
Patient status: Alive, emigrated, dead. 
▪ 
Surgical approach. 
▪ 
Date of death 
▪ 
Head size 
DNPR: 
NOMESCO (Nordic Medico-Statistical Committee) Classification of Surgical Procedures codes and 
Charlson comorbidity index. 
 
 
Statistical analysis 
We will stratify patients into two groups according to whether they received a cemented or an uncemented 
acetabular component after the first revision. We will use descriptive statistics for the baseline 
characteristics of the two groups. We will use mean or medians for continuous variables and the total 
number and percentage of the total for categorical variables. The cumulative incidence of revision will be 
estimated using Fine-Gray regression to model the cumulative incidence function, accounting for the 
competing risk of death (16). We will employ absolute risk regression function to evaluate the relative 
difference in the absolute risk of experiencing the outcomes of interest within the observation period and 

 
 
 
 Cementation of cup and the risk of second revision: 8 
 
the corresponding 95% Confidence Interval (95% CI) in patients with a cemented acetabular component 
compared to patients with an uncemented acetabular component (17). This will be performed using both 
crude and multivariable adjusted models. We will adjust for age, sex, Charlson Comorbidity Index (CCI). As it 
was shown that the risk revision increased over time in previous studies (18). we will also adjust for the 5-
year intervals during which the primary operation was performed. P-values ≤ 0.05 will be considered 
statistically significant. The most recent version of R (www.r-project.org) will be used for data handling and 
the statistical analysis. 
 
 
 
Table 1: Baseline characteristics at time of first revision 
 Parameter 
First revision with 
cemented acetabular 
component 
First revision with 
cementless acetabular 
component 
Standardized difference 
of the means or 
prevalences 
N 
 
 
 
Female sex, N (%) 
 
 
 
Age at first revision, 
 
 
 
Left side, N (%) 
 
 
 
CCI 
1-2 
 
 
 
3-4 
 
 
 
≥5 
 
 
 
Exchange of Femoral 
components  N (%) 
 
 
 
Indication of revision N 
(%) 
 
 
 
Aseptic loosening 
 
 
 
Dislocation  
 
 
 
Infection 
 
 
 
Fracture 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 9 
 
Osteolysis/granuloma 
without loosening  
 
 
 
Components failure 
 
 
 
Pain 
 
 
 
Polyethylene wear 
without loosening 
 
 
 
Other 
 
 
 
Revision type N (%) 
 
 
 
Uncemented 
 
 
 
Hybrid 
 
 
 
Cemented 
 
 
 
Date of primary surgery 
1995-1999 
 
 
 
2000-2004 
 
 
 
2004-2009 
 
 
 
2010-2014 
 
 
 
2015-2019 
 
 
 
2020-2021 
 
 
 
Acetabular bone loss 
 
 
 
Type 1-2 
 
 
 
Type 3-4 
 
 
 
Type 5 
 
 
 
Unclassified  
 
 
 
Time until first revision 
 
 
 
< 1 year 
 
 
 
1-5 years 
 
 
 
> 5 years 
 
 
 
Head size at primary surgery 
28 mm, N (%) 
 
 
 
32 mm, N (%) 
 
 
 
36 mm, N (%) 
 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 10 
 
Table 2 
Component revised 
N 
Number of 
revisions (%) 
Relative Absolute 
risk [95% CI] 
Adjusted Relative 
absolute risk [95%] 
P value for the 
adjusted model 
Acetabular 
 
 
 
 
 
Cemented 
 
 
 
 
 
Cementless  
 
 
 
 
 
All 
 
 
 
 
 
Cemented 
 
 
 
 
 
Cementless 
 
 
 
 
 
 
Table 3: Stratifying for the indication of the second revision between cemented and uncemented acetabular 
component 
Indication of revision N 
(%) 
Cemented acetabular 
component 
Cementless acetabular 
component 
Standardized 
difference 
P value 
Aseptic loosening 
 
 
 
 
Dislocation 
 
 
 
 
Infection 
 
 
 
 
Fracture  
 
 
 
 
Osteolysis/granuloma 
without loosening  
 
 
 
 
Components failure 
 
 
 
 
Pain 
 
 
 
 
Polyethylene wear 
without loosening 
 
 
 
 
Other 
 
 
 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 11 
 
Ethical considerations 
 This study is a part of a bigger study which was approved by the local Danish Data Protection Agency (id: P-
2022-717) and carried out in compliance with The General Data Protection Regulation and the 1964 
Declaration of Helsinki. Patient information is anonymized for privacy protection. All identifiers will be 
removed or encrypted to ensure anonymity prior to analysis. Access to data will be exclusive to authorized 
personnel, and all data will be secured in encrypted databases. The study results will be reported with full 
honesty and transparency, and any potential conflicts of interest will be transparently disclosed. 
Confidentiality and anonymity of data subjects will be guaranteed in all publications and presentations. 
 
 
Clinical implications 
A comparison was conducted to assess the risk of second revision surgery in patients who underwent 
cemented versus non-cemented total hip arthroplasty (THA) due to acetabular component failure. The goal 
was to gain new insights into the likelihood of requiring a second revision surgery specifically due to 
acetabular component failure in primary THA patients. This could be influenced by the type of fixation 
technique used, whether cemented or non-cemented. The anticipated outcome of this research is to provide 
valuable information that can aid in selecting the most appropriate fixation technique by addressing a lesser-
known aspect of complications associated with different fixation techniques.  
 
Reporting and trial registration 
As a register-based study, this research will be reported in convenience with the Reporting of Studies 
Conducted using Observational Routinely-collected Data (RECORD) statement. The study protocol will be 
made available on a freely accessible, open access preprint archive. 
 
Funding 
The current study has not received funding.  
 
 
 
 
 

 
 
 
 Cementation of cup and the risk of second revision: 12 
 
 
 
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