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RCT
ACE Report #5217

Standard THA, large-head THA and RHA yield similar long-term functional outcomes


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

Similar range of motion and function after resurfacing large-head or standard total hip arthroplasty

Acta Orthop. 2013 Jun;84(3):246-53. doi: 10.3109/17453674.2013.788435. Epub 2013 Mar 26

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Synopsis

76 patients with primary osteoarthritis and secondary osteoarthritis due to mild dysplasia were randomized to receive either standard total hip arthroplasty (THA), large-head THA, or resurfacing hip arthroplasty (RHA) to examine the differences between these three treatments on long-term clinical function. Results at 2 years indicated that, although incision length and surgical time were significantly higher in the RHA group, there were no significant differences between groups in range of motion, Harris Hip scores (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, UCLA activity scores, step rate or sick leave. There was no clinically relevant difference between groups in quality of life.

Publication Funding Details +
Funding:
Non-Industry funded
Sponsor:
The Danish Ministry of the Interior and Health
Conflicts:
None disclosed

Risk of Bias

5.5/10

Reporting Criteria

18/20

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.

4/4

Randomization

2/4

Outcome Measurements

4/4

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?

Previous research has found that large-head total hip arthroplasty (THA) or resurfacing hip arthroplasty (RHA) have several advantages when compared to standard THA, namely increased range of motion, decreased patient anxiety and reduced risk of dislocations. In addition, past literature has found that when compared to THA, RHA requires a larger incision, resulting in an immediate disadvantage but no long-term effect on function. However, in order to access the acetabulum, RHA also requires detachment of a section of gluteus maximus and this can cause long-term decreases in function. The present study aimed to compare the effects of standard THA, large-head THA and large-head RHA on long-term patient function.

What was the principal research question?

How did large-head RHA and THA compare to standard THA with respect to clinical function, when assessed at 2 years, in patients with primary and secondary osteoarthritis?

Study Characteristics -
Population:
76 patients (age range: 40-65 years) with primary osteoarthritis and secondary osteoarthritis due to mild dysplasia.
Intervention:
RHA group (n=21): Patients in this group underwent resurfacing hip arthroplasty using an Articular Surface Replacement (ASR; DePuy, Leeds, UK) consisting of a high-carbon cobalt-chromium-molybdenum alloy. The median head size for this procedure was 51 mm (47-57mm). Their rehabilitation program consisted of full weight bearing in a home-based training program. Median age = 57 years (range 54-61); 40% female. Large-head THA (n=18): Patients in this group underwent total hip arthroplasty using M2aMagnum/ReCap articulation (made of cast high-carbon cobalt-chromium. The median head size for this procedure was 50 mm (44-56 mm). The stem was a cementless forged titanium Bimetric stem. Their rehabilitation program consisted of full weight bearing in a home-based training program. Median age = 63 years (range 54-64); 47% female.
Comparison:
Standard THA (n=34): Patients at the Odense University Hospital underwent total hip arthroplasty using a Mallory Head acetabular shell with an Arcom Ringlock polyethylene liner. The head size used in this group was 28 mm. A Biolox delta modular ceramic head and a titanium Bimetric stem (Biomet, Bridge End, UK) were used at this center. Patients at Hospital South, Naestved underwent total hip arthroplasty using a cobalt-chromium head (28 mm), a titanium Trilogy CH cup and a VerSys Fiber titanium metal taper stem. The first 9 patients at this center received a Trilogy UHMWPE liner and the next 6 patients received a Longevity liner (Zimmer, Warsaw, IN). Their rehabilitation program consisted of full weight bearing in a home-based training program. Median age = 56 years (range 52-62); 29% female.
Outcomes:
Outcomes included range of motion, extension, the Harris Hip Score (HHS), the UCLA activity score, walking activity (assessed using the Yamax (YX200) pedometer), quality of life (assessed using the EQ-5D), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), surgical time, blood loss, length of incision, complications, hemoglobin levels and length of hospital stay.
Methods:
RCT: Multi Center
Time:
Follow-up examinations were conducted at 8 weeks, 6 months, 1 year, and 2 years.

What were the important findings?

  • There was no significant difference between groups in blood loss (p=0.09), decrease in haemoglobin (p=0.50), length of hospital stay (p=0.80), flexion (p>0.05), internal rotation (p>0.05) and external rotation (p>0.05). Surgical time and incision length were significantly higher in the RHA group (p<0.001).
  • At 2 years, there was no significant difference in total range of motion between standard THA and large-head THA (p=0.60) or RHA (p=0.50).
  • Adduction, when measured at earlier time points, was significantly improved in the RHA group and large-head THA group, compared to standard THA at 8 weeks (p=0.02) and in the RHA group compared to the standard THA group at 6 months (p=0.03). At subsequent time points, no significant difference was observed between groups (p>0.05).
  • Although no significant differences observed at the earlier time points, there was a significant reduction in extension in the large-head THA group compared to the two other groups at 2 years (p<0.01). The same trend was observed in abduction in the RHA group (p=0.02 at 2 years in favour of the two THA groups).
  • At one year, all groups had received a HHS in the "excellent" category, with no significant differences between groups at 2 years (p>0.05). UCLA activity scores, WOMAC scores, and step rate were also not significantly different between groups at 2 years (p>0.05).
  • Quality of life was similar between groups up until the 2-year follow-up, with the large-head THA group obtaining significantly higher scores (p<0.05). There was no significant difference in sick leave between groups (p=0.80).
  • Complications included 1 cup displacement with dislocation and 1 suspected infection in the RHA group, 1 pulmonary embolus following a deep vein thrombosis and 1 incidence of pain and raised metal ion levels in the large-head THA group, as well as 3 dislocations in the standard THA group.

What should I remember most?

There were no significant differences between standard total hip arthroplasty (THA), large-head THA, or resurfacing hip arthroplasty (RHA) in range of motion, Harris Hip scores (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, UCLA activity scores, step rate or sick leave, when assessed at 2 years. However, surgical time and incision length was significantly higher in the RHA group. Lastly, there was no clinically relevant difference in quality of life at 2 years.

How will this affect the care of my patients?

The results from this study suggest that standard total hip arthroplasty (THA), large-head THA, and resurfacing hip arthroplasty (RHA) are all comparable treatments in the management of primary and secondary osteoarthritis. It is important to note that this study had a small sample size; although certain trends were observed in the data, it did not have enough power to detect any potential differences. Studies using larger sample sizes are necessary to conclusively determine if differences in clinical function exist between these three treatments. Furthermore, the metal ion concentrations due to the metal-on-metal nature of the resurfacing technique, as well as the adverse events associated with these increased concentrations should be considered when choosing a treatment option.

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