Retrospective Study About the Long-term Outcomes of Conical Tapered Stems in Cementless Total Hip Arthroplasty for Osteoarthritis Due to Congenital Hip Pathologies
Conditions: Dysplasia; Hip, Prosthesis Survival
Sponsor: Istituto Ortopedico Rizzoli

March 18th, 2022 
NCT 04748458 
Study ID: 589/2020/Oss/IOR 
Date of approval: 17/06/2020 
Title: Long-term Outcomes of Conical Tapered Stems in Cementless Total Hip Arthroplasty Due to 
Congenital Hip Pathologies (RetroCone) 

Study start: July 17, 2020 
Primary completoo: October 1, 2021 
Study completoo: October 2, 2021 
Brief summary 
A retrospectie consecutie populaton of patents treated with conical tapered stems in cementless total 
hip arthroplasty for osteoarthrits due to congenital hip pathologies will be selected. The aim of this 
retrospectie study is to eialuate the long-term clinical and radiographic results of this implant and the 
suriiial rates in such a specifc cohort. 
Study descriptoo 
Congenital hip pathologies may seierely alter the local anatomy of the hip, making total hip arthroplasty 
(THA) due to osteoarthrits afer congenital hip pathologies challenging. While it seems that congenital hip 
pathologies did not signifcantly infuence the outcomes when compared to THA afer osteoarthrits, the 
choice of implant was demonstrated to impact the suriiial rates of the THA afer congenital hip 
pathologies. 
To date, no guidelines exist about the correct choice of hip implant in congenital hip pathologies: only mid-
term case series are aiailable. Conical tapered stems haie been frequently suggested for the most difcult 
cases. 
The aim of this study is to describe the suriiial rates and the long-term clinical and radiological outcome of 
conical tapered stems in THAs afer congenital hip pathologies. 
Populatoo 
retrospectie, consecutie adult populaton treated with conical tapered stems in cementless total hip 
arthroplasty for osteoarthrits due to congenital hip pathologies. 
Inclusion Criteria: 
Symptomatc hip osteoarthrits due to congenital hip pathologies 
Consecutie populaton with a minimum follow-up of 2 years 
Cementless total hip arthroplasty with conical tapered stem 
Pre-operatie planning using CT 
Complete clinical and radiographic assessment 
Exclusion Criteria: 
Other type of hip osteoarthrits 
Other type of implants 
Inadequate pre-operatie planning (eg: no CT) 
Incomplete clinical and radiographic assessment 
Methods 
Demographics of the patents iniolied were collected using medical records. 
The patents were clinically and radiographically eialuated in the post-operatie setng at 1, 6, 12, 2  
months and then biennial. Harris Hip score (HHS) was adopted to clinically assess the patents at the fnal 
follow-up []. Plain antero-posterior peliis radiographs were taken at eiery follow-up: the last X-ray was 
eialuated for the positonal parameters specifed in the table []. Osseointegraton was eialuated using the 
criteria of Moore et al. (cup) and Engh et al. (stem) []. 
Failures were collected and the suriiial rates were specifed, using a 955 confdnce interial. 
Statstcal aoalysis plao 
Statstcal analysis has been done by using Windows SPSS 1 .0, 1 .0.1 iersion (SPSS Inc, Chicago, IS) and 
JMP, 12.0.1 iersion (SAS Insttute Inc, Cary, NC, 1989-2007). 
The quantitative data were expressed as average values, standard deviations and ranges of minimum and 
maximum. The qualitative data were expressed ss frequencies and percentages. The survivorship of the 
primary THA implants were calculated and plotted according to Kaplan-Meier method (95% confidence 
interval). The endpoint was removal or change of any component. The implants were followed until the last 
date of observation (date of death or 31 December 2019). A p-value less than 0.05 was considered 
statistically significant.