A Randomized RSA Study Comparing HXLPE to Conventional Polyethylene in Cemented Total Hip Arthroplasty

March 30, 2020 updated by: Kjell G Nilsson, Umeå University

A Randomized Controlled RSA Study Comparing the 2nd Generation Highly Cross-linked Polyethylene to Conventional Polyethylene in Cemented Total Hip Arthroplasty

A prospective randomized study comparing two types of cemented acetabular components, a highly-crosslinked polyethylene or conventional polyethylene in total hip arthroplasty. Primary outcome are component wear measured by RSA, secondary outcomes are migration and complications. Patients are evaluated 5 years postoperatively.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Background:

Total hip replacements is a cost effective treatment of a symptomatic degenerative hip disease. Cemented total hip replacements are the most common implants in Sweden (Swedish hip registry, 2009).

Wear of ultra high molecular weight polyethylene has been a issue with regard to implant survival. At the time of the shift of the millennium highly cross-linked polyethylene was introduced to the markets. Experimental studies had shown reduction of wear in hip simulator studies (McKellop,1999). Subsequently the intention is to reduce osteolysis and implant loosening. Single surgeon pilot studies in the 1970 (Wroblevski et al. 1996, Oonishi 1998, Grobelaar 1999) were the first clinical series with good results leading to the development of 2nd generation highly cross-linked polyethylenes which is now the almost exclusively used PE worldwide. So far medium term clinical evaluation and laboratory assessment have showed reduced wear and good mechanical properties (Digas et al. 2003, 2004, 2007, Röhrl et al. 2005, 2007, D´Antonio et al. 2005)

Production of highly crosslinked polyethylene (HXLPE) consists of several steps. First the PE material is crosslinked by being subjected to either gamma irradiation of various intensity or electron beam irradiation. The second step is to remove the free radicals created during the irradiation. This is done either by annealing (i.e. warming up the PE to just under its melting temperature) or melting (i.e. warming up the PE to above its melting temperature). Finally, the implant is sterilized either by gamma irradiation or Ethylene Oxide and packed in vacuum or inert atmosphere.There are some possible drawbacks and challenges in the process of cross-linking polyethylene with regard to preserving the mechanical properties and elimination of free radicals (Kurtz et al. 2006, Currier et al. 2007).

Submelt annealing preserves mechanical properties but on the other hand cannot eliminate all free radicals existing in the PE. Retrieval-studies of some 2nd generation highly cross-linked polyethylenes manufactured in this way have shown signs of oxidation. The in-vivo oxidation has been located in the non articulating area such as the circumference of the acetabular liner. It has been discussed that the femoral head may protect the polyethylene against oxidation, and hence prevent the possible negative consequences of remaining free radicals (Currier et al 2007).

Melting the polyethylene eliminates all free radicals but alters the mechanical properties. This has led to PE cracks and implant failure in some clinical studies (Furmanski et al. 2009), whereas it has not been seen in other.

Finally, wear particles of highly crosslinked polyethylene are more often in the submicron size compared to conventional PE. Although these particles have a higher biological activity (Fisher et al. 2006), results of recent studies show however, that the overall risk for osteolysis and aggressiveness of highly cross-linked particles is reduced (Galvin et al. 2007).

Because of differences in the manufacturing processes of highly crosslinking PE between manufacturers (i.e. different GUR used, type of irradiation, intensity of irradiation, postirradiative treatment, type of sterilization and packing, etc, etc) all highly crosslinked polyethylenes differ somewhat from each other. One can not extrapolate results of in vitro or in vivo wear studies of one manufacturer to another. Also, because of these manufacturing differences, fixation characteristics may differ between the various types of HXLPEs. Therefore it is imperative that all new highly crosslinked polyethylenes are subjected to clinical studies of their wear and fixation performance using high accuracy methods before being used extensively.

Methods:

A prospective randomized study comparing acetabular components made of HXLPE or conventional PE in total hip arthroplasty. The study will be conducted at Department of Orthopaedics, Umeå University, Umeå, Sweden.

Aim of study The aim of the study is to compare the wear and migration of a 2nd generation polyethylene from Link with conventional polyethylene in an all-poly cemented acetabular cup of the Lubinus brand using radiostereometric analysis (RSA) with 5-year follow-up.

Hypothesis The H0-hypothesis is that the difference with in wear between HXLPE and conventional PE will not increase up to 5-year follow-up.

Material Patients (age 50 years and above) with primary osteoarthritis between 2013 and 2014 at the orthopaedic department at the county hospital (Lycksele) affiliated to Umeå University hospital, Sweden. Patients were treated with a cemented total hip arthroplasty. At surgery, after the acetabulum was reamed, randomization was performed by opening of a consecutively numbered sealed envelope informing whether a cup made of HXLPE or conventional PE should be inserted. The envelopes were kept far away from the operation theatre and were opened by a research nurse contacted by telephone. Randomization was stratified for gender. Within each stratum there was block randomization with 6 permutations in each block.

Patients have been followed for 5 years postoperatively.

Implants • Acetabular cup Intervention: Link-Ticona GUR 1020 HXLPE, 32 mm inner diameter (Trade name Lubinus® X-LINKed® )

Control: Link-Chirulene GUR 1020 UHMWPE, 32 mm inner diameter (Trade name Lubinus ® UHMWPE)

• Femur stem Test and control: Lubinus® SP II®, CrCo femoral head, 32 mm diameter

Radio Sterometric Analysis (RSA) Radiostereometric analysis measurements will be performed 5 years postoperatively.

Wear will be measured as penetration of the femoral head into the polyethylene in the proximal, proximo-medial (2D pm), proximo-posterior (2D pp), and proximo-medial-posterior (3D) directions. Since the penetration during the initial 3 months represents polyethylene yield or bedding in, wear measurements will be reported from 3 months and up to 5 years postoperatively.

Quality of cup fixation will be measured as rotations of the cup around the three cardinal axes in relation to acetabulum with the postoperative examination as reference.

The RSA measurements will be analysed at Umeå University Hospital. Patient data will be saved in a specific research database at Umeå University Hospital following specific guidelines from the national data security committee.

Ethical approval The study has been approved by the Ethics Committee of Umeå University (Dnr 2011-173-31M, 2018-34-31M).

Sample size With a mean difference in wear at 2 years of 0.1 mm or more (SD ± 0.1) between the groups (p< 0.05), 25 patients in each group will give a power of > 80%. In order to cater for losses during the follow up a total of 57 patients will be enrolled.

Scientific Value All new materials should be monitored closely and introduced in small study groups using a high precision measurement technique. Many markets require such tests before acceptance for general use is given. The new highly crosslinked polyethylene from Link-Ticona is not equivalent to current highly crosslinked polyethylenes on the market, and one can not extrapolate wear results from these other designs.

Study Type

Interventional

Enrollment (Actual)

57

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Sweden
      • Lycksele, Sweden, 921 37
        • Lycksele Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

50 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Primary osteoarthritis
  • Age 50 years and above
  • Patients who understand the conditions of the study and are willing to participate for the length of the prescribed follow-up

Exclusion Criteria:

  • Rheumatoid Arthritis
  • Grossly abnormal hip anatomy (severe dysplasia)
  • Fracture sequelae
  • Patients who, as judged by the surgeon, are mentally incompetent or are reasonable unlikely to be compliant with the requirements of the study
  • Immune suppression or grave systemic illness

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: TREATMENT
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: NONE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Acetabular cup HXLPE (Intervention)
Randomization to HXLPE acetabular component.
Procedure: Device: Randomization between prosthetic components
Patients are randomized between two types of cup components in total hip arthroplasty. Identical cups made of either highly-crosslinked polyethylene or conventional polyethylene.
EXPERIMENTAL: Acetabular cup Conventional PE (control)
Randomization to Coventional PE as control group
Procedure: Device: Randomization between prosthetic components
Patients are randomized between two types of cup components in total hip arthroplasty. Identical cups made of either highly-crosslinked polyethylene or conventional polyethylene.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Magnitude of Polyethylene Wear
Time Frame: 0-5 years
The size of the femoral component penetration into the polyethylene measured in millimeters per year and the volumetric annual wear millimetres with radiostereometric (RSA) analysis of radiographs.
0-5 years

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Magnitude of Cup Migration
Time Frame: 0-5 years
Migration measured in millimetres per year with radiostereometric (RSA) analysis of radiographs. Radiostereometric analysis (RSA) is a stereo X-ray technique used in clinical research studies to evaluate micro-motion and wear of orthopaedic implants within bone. The method has a high accuracy and precision. Technical requirements include the need for implanted marker beads and radiograph view angles determined by a calibration cage.
0-5 years
Surgical complications
Time Frame: 0-5 years
Surgical complications and reapportions during the study period.
0-5 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Umeå University

Investigators

  • Principal Investigator: Kjell Nilsson, Professor, Umea University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

February 7, 2013

Primary Completion (ACTUAL)

December 4, 2014

Study Completion (ACTUAL)

June 30, 2019

Study Registration Dates

First Submitted

March 24, 2020

First Submitted That Met QC Criteria

March 25, 2020

First Posted (ACTUAL)

March 26, 2020

Study Record Updates

Last Update Posted (ACTUAL)

April 1, 2020

Last Update Submitted That Met QC Criteria

March 30, 2020

Last Verified

March 1, 2020

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PolyvsHXLPE

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

On request

IPD Sharing Time Frame

Publication at 1 year after completion of the study during 2020.

IPD Sharing Access Criteria

International scientific peer-reviewed journal

IPD Sharing Supporting Information Type

  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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