Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT06019026 |
| Other study ID # |
Tri-Lock vs. Summit |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
January 1, 2015 |
| Est. completion date |
June 10, 2023 |
Study information
| Verified date |
September 2023 |
| Source |
Regional Hospital Holstebro |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The incidence of primary hip joint prosthesis is 180 per. 100,000 inhabitants. In male
patients younger than 50 years the 10-years survival of the prosthesis is 89 % and 82 % over
15 years. In women younger than 50 years the 10-years survival of the prosthesis is 87 % and
78 % over 15 years.
As revision surgery is associated with higher complication risk for the patient and poorer
out-come and implant survival it is necessary to examine possible methods that may increase
long-term survival of the primary hip prosthesis or facilitate better outcomes after revision
of hip joint prostheses for younger patients.
In younger patients the prosthesis often is inserted without the use of cement. When not
using cement, it is crucial for the final result, that there is a direct bone ingrowth of the
prosthesis. The chance of getting bone ingrowth depends firstly on a good immediate
mechanical fixation at surgery and secondly on osteoconductive abilities of the prosthetic
surface.
This study investigates a new bone sparing implant with a new surface compared to a
conventional implant.
Description:
BACKGROUND
According to the Danish Hip Arthroplasty Registry 201 approximately 10.400 primary hip joint
prostheses in Denmark are implanted annually, and the incidence is relatively stable. The
incidence of primary hip joint prosthesis in population was 180 per. 100,000 inhabitants in
2014, with a slight predominance of female patients (60%). The average age for women is 70
and for men 67 years. Idiopathic arthritis is diagnosed in 80% of all patients receiving a
hip joint prosthesis [1,2]. For older patients, the risk of later revision of a hip joint
prosthesis is small. The overall survival of the primary hip joint prostheses is for all
diagnoses 82% after 19 years. The prosthesis survival is poorer for younger patients, and for
women. In male patients younger than 50 years the 10-years survival of the prosthesis is 89 %
and 82 % over 15 years. In women younger than 50 years the 10-years survival of the
prosthesis is 87 % and 78 % over 15 years. [2]. As revision surgery is associated with higher
complication risk for the patient and poorer outcome and implant survival it is necessary to
examine possible methods that may increase long-term survival of the primary hip prosthesis
or facilitate better outcomes after revision of hip joint prostheses for younger patients.
In younger patients the prosthesis often is inserted without the use of cement. When not
using cement, it is crucial for the final result, that there is a direct bone ingrowth of the
prosthesis. The chance of getting bone ingrowth depends firstly on a good immediate
mechanical fixation at surgery and secondly on osteoconductive abilities of the prosthetic
surface. From a theoretical point of view it is also important that elastic properties of the
prosthesis differ as little as possible from the elastic properties of the bone, in order to
prevent a subsequent loss of bone.
INVESTIGATED IMPLANTS
The Tri-Lock femoral implant from Depuy ® is in its basic design a well-known implant that
has been used since 1981 with documented good long-term results. It is an implant with
bone-preserving properties and proximal coating, providing a predominantly metaphyseal
anchoring. The Summit femoral implant from Depuy ®, is newer to the marked, and has a longer
diaphyseal support but is predominantly metaphyseally fixed. A proximal porous implant
coating will increase the surface area in contact with the metaphyseale bone and increase the
coefficient of friction compared to mid-coated implants [3,4,5]. Proximal coatings may on the
positive side lessen periprosthetic bone stress shielding, however, on the negative side,
proximal coatings may reduce primary prosthesis fixation and lead to fibrous membrane
formation with consequently implant micromotions that will eventually causing aseptic
loosening of the im-plant. Hypothetical extensively coated implants have a larger porous
surface and thus provide better and faster primary fixation, but there are no publications of
randomized prospective clinical studies to support this. There are different porous coatings
on the two investigated femoral components. Summit is coated with Porocoat porous coating,
whereas Tri-Lock in the latest version is coated with the new GRIPTION technique for an even
larger surface for bone ingrowth (Gription) with a new ultra-porous surface marketed as an
improved immediate im-plant fixation in the bone. The total surface of the metaphyseal
implant part is increased by approximately 25% with the Gription coating technique. The
Gription technique may provide consistent implant seating height and additional initial
stability, and these qualities may in long term ensure an improvement on implant survival.
Both femoral implants are made of Titanium. The Tri-Lock stem is designed with a reduced
lateral shoulder to preserve bone in the greater trochanter, and with a shorter stem and an
oblique cut stem tip, as compared to the Summit stem, in order to enhance stem insertion
through minimally invasive approaches.
PRIMARY OUTCOME Mechanical loosening of a prosthesis may be suspected if the prosthesis
migrates with respect to the surrounding bone [6;7]. Therefore, there is now consensus that
the introduction of new implant designs including coatings and also new surgical methods
should be evaluated in migration studies before they can be recommended for use in general
[8;9]. Using Radiostereometric Analysis (RSA), it is now possible to get a very accurate
assessment of prosthesis migration with a precision of at least 0.11 mm [10]. Clinical
studies have shown that early migration of uncemented prostheses is related to the subsequent
loss of the prosthesis [11;12]. For RSA tantalum beads are inserted in the prosthesis and
surrounding bone. Immediately post-operatively stereoradiographs (RSA images) are made, and
the initial position of the prosthesis relative to the fixed bead markers of the bone is
determined. At defined time intervals new RSA images are taken. By comparison of the images
the prosthesis migration in relation to the bone fixing points is determined in three
dimensions, as a function of time.
Bone mineral density (BMD) around the inserted implants can be quantified by Dual Energy
X-ray absorptiometry (DXA), which is an accurate method for the measurement of even small
changes in BMD around femoral components [13]. DXA has been used to detect decreased bone
resorption around implants with a lower stiffness [14]. A recent study from Finland
demonstrated increased stem subsidence in patients with low BMD, and it is therefore
advisable to screen studied patients for osteoporosis preoperatively. [15].
MATERIAL & METHODS
Design: Prospective randomized clinical study. Logistics: All newly referred patients with
hip pain diagnosed with primary osteoarthritis and scheduled for hip replacement will be
screened for elegibility in the study according to the study criteria. Assessed patients to
be a candidate for project participation, given oral information for participants at the
clinic the same day and handed over documents relating to the project. 1-2 weeks prior to
surgery the patient participates in a general information session about the surgery and
post-operative recovery. Here, the selected patients who wish to partici-pate in the project
sign the consent form. Patients will at information day after signed consent be given an
Ipad, in order to answer our questionnaires. Furthermore, there will also be conducted
preoperative DXA scan.
After informed consent and using the following inclusion criteria, patients are randomized to
insertion of metafysial fixed femur implant with proximal porous coating porocoat (Summit,
Depuy®) or proximal Grip Tion coat (Tri-Lock, Depuy®). All patients are inserted dan same
uncemented acetabular component (Pinnacle cup Depuy®). Randomization is done intraoperatively
in a sealed envelope system.
RSA analysis: We will use CAD models for the femur implants, and we expect to use EGS-RSA to
the acetabulum implants.
POWER:
Based on the primary endpoint (RSA) and using the following values: α= 0.05, β= 0.10 (power
90), SD = 0.6 mm, and MIREDIF: minimum relevant difference = 0.6 mm [16], sample size is 23
patients for each arm in the study.
Taking into account the risk of dropout and death in the study group inclusion is set at 25
patients per group in order to ensure that a minimum of 2 x 23 patients (46 patients) will
have full follow-up of efficacy parameters at 2 years of follow-up.
ON RADIATION DOSE
Measurements were taken for the radiation dose, which shows that the stereo x-ray of the hip
provides a radiation dose of 0.015 mSv [18]. This represents approximately 50% of a
conventional recording of the hip. It is shown that a typical DXA measurement of the femur or
spine (osteoporosis control) produce an effective dose equivalent to 0.015 mSv [19].
Conventional X-ray of the hip, gives a dose of 0.85 mSv. Normally, our hip prosthesis
patients not included in this study have taken radiograph least one time within the first
postoperative year. Patients in this study will have taken the same number of conventional
radiographs, and in addition to 5 times DXA scan and seven times the stereoradiography. Taken
from above radiation dose, patients included in this study were subjected to an additional
radiation dose of 1.93 mSv. This corresponds to have taken three additional conventional
radiographs of the hip, and it provides an additional risk of fatal cancer of 0.01%. This
places the subjects in group IIb, where the overall risk of the irradiated individual is 1 to
10,000. [19]
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fiber-mesh coat-ed femoral stems. Acta Orthop. 2011 Jun;82(3):308-14. Epub 2011 Apr 19
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