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Volume:2 Issue:4 Number:162 ISSN#:2563-5476
RCT
ACE Report #4364

THA: Stem migration and bone loss similar in cementless vs. cemented femoral components


How to Cite

OrthoEvidence. THA: Stem migration and bone loss similar in cementless vs. cemented femoral components. ACE Report. 2013;2(4):162. Available from: https://myorthoevidene.com/AceReport/Report/4364

Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:N/A

Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry: 43 hips followed for 2 years in a prospective trial

Acta Orthop. 2012 Dec;83(6):592-8. doi: 10.3109/17453674.2012.742393. Epub 2012 Nov 1

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Synopsis

51 patients, including 52 hips, undergoing treatment for osteoarthritis were randomized to receive either reverse hybrid (cemented polyethylene cup with cementless femoral stem) or conventional cemented total hip replacement (both components cemented) to determine if there was a difference in outcome between the techniques. Clinical outcome, wear, component migration and bone remodeling were recorded over 2 years postoperatively. The results showed that there were no major differences between the two procedures. This study indicated that the reverse hybrid procedure does not provide improved outcomes when compared to the conventional cemented method in total hip replacement.

Publication Funding Details +
Funding:
Not Reported
Conflicts:
None disclosed

Risk of Bias

6.5/10

Reporting Criteria

14/20

Fragility Index

N/A

Was the allocation sequence adequately generated?

Was allocation adequately concealed?

Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?

Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?

Blinding Patients: Was knowledge of the allocated interventions adequately prevented?

Was loss to follow-up (missing outcome data) infrequent?

Are reports of the study free of suggestion of selective outcome reporting?

Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?

Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?

Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.

1/4

Randomization

3/4

Outcome Measurements

2/4

Inclusion / Exclusion

4/4

Therapy Description

4/4

Statistics

Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

The Swedish Hip Arthroplasty and Norwegian Arthroplasty Registers have shown increased use of reverse hybrid technique (cemented polyethylene cup with cementless femoral stem) in total hip replacement. This is in part is due to the observed improvement in survivability of the cementless stems with respect to component loosening. However, there has been concern regarding polyethylene wear induced by hydroxyapatite (HA) in HA-coated implants, commonly seen in reverse hybrid total hip replacements. Also, there has not been a study conducted that has shown that the reverse hybrid technique is superior to conventional cemented total hip replacement, indicating the need for this study.

What was the principal research question?

Does the reverse hybrid total hip replacement technique provide superiority to conventional cemented total hip replacement with respect to clinical results, wear, remodeling of the bone, component migration, or component loosening after 2 years?

Study Characteristics -
Population:
51 patients (52 hips) with osteoarthritis undergoing total hip replacement with cemented all-polyethylene cup. (n=43 total hips from 42 patients completed follow-up)
Intervention:
Reverse Hybrid Group: Patients underwent reverse hybrid total hip replacement with a cementless femoral stem, including proximal HA coating on top of the metal coating, tantalum balls attached at the tip, calcar region, and neck for radiostereometry analysis (RSA), and a 28-mm cobalt chrome head. (n=19 hips from 19 patients)
Comparison:
Cemented Group: Patients underwent conventional cemented total hip replacement with cemented femoral stem, with tantalum markers attached to the tip, calcar region and head (for RSA), and a 28-mm cobalt chrome head. A polyethylene distal cement restrictor was used and cement was pressurized prior to prostheses insertion. (n=24 hips from 23 patients)
Outcomes:
Clinical outcomes were measured using Harris hip and Oxford hip scores for function and pain. Component wear and migration/rotation were evaluated using RSA. Bone remodeling and bone loss as a change in bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry. Component loosening was analyzed via lucency in radiographs.
Methods:
RCT, Single-centre
Time:
RSA and BMD follow-up was conducted at 6 months, 1 and 2 years postoperatively. Follow-up of clinical outcomes (Harris and Oxford hip scores) and radiographic analysis were conducted at 2 years postoperatively.

What were the important findings?

  • Similar improvements in Harris hip and Oxford hip scores were observed in both groups.
  • There were no significant differences observed between groups in the amount of wear in the x- (p=0.9), y- (p=0.9), and z-axes (p=0.08), and the vectorial resultant 3D wear (p=0.7).
  • Cup and stem component migration in any direction (x-, y-, or z-axes) were observed to not significantly differ between groups.
  • Rotation of stem component did not significantly differ between groups. Rotation of cup component in the y- and z-axes was not significantly different between groups. Rotation of the cup component in the x-axis was -0.24 degrees (95%CI -0.55 to 0.07) in the RH group and 0.13 degrees (95%CI -0.08 to 0.34) and in the cemented group, resulting in significant difference (p=0.03).
  • Bone remodeling around the cup was found to be similar between groups.
  • Significant bone loss in Gruen Zone 1 of the femur was observed in the RH group (18%, 95%CI 11-24%) when compared to the cemented group (1.4%, 95%CI -3.2-5.9%) (p<0.001). Bone loss in remaining Gruen zones (2-7) was not significant between groups.
  • There were no significant differences between groups for incidence of component loosening (p>0.05).

What should I remember most?

The use of a cementless stem in total hip replacement provided similar results to a cemented stem with regards to Harris hip and Oxford hip scores, wear, component migration/rotation, bone remodelling, and bone loss after 2 years. Although significantly higher bone loss in Gruen Zone 1 was associated with the cementless stems, it is unlikely that it is an important clinical finding due to the long-term survivability of the cementless stems.

How will this affect the care of my patients?

There are no major differences between a cementless and a cemented femoral stem in total hip arthroplasty after 2 years. An extended study with a longer follow-up period is necessary to investigate any differences that may exist between the two techniques.

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