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Primary Total Resurfacing Hip Replacement

 

Demographics

There have been 13,307 total resurfacing procedures reported to the Registry, an additional 1,214 procedures compared to the last report. The use of resurfacing hip replacement in Australia continues to decline. The number of procedures reported in 2009 was 17.6% less than 2008 and 34.6% less compared to the peak in 2005.

Osteoarthritis is the principal diagnosis for total resurfacing hip replacement (94.6%), followed by developmental dysplasia (2.7%), avascular necrosis (1.8%), rheumatoid arthritis (0.4%) and other inflammatory arthritis (0.4%).

Most patients are male and the proportion of males has increased from 71.2% in 2003 to 83.7% in 2009 (Figure HT31).

There has been a slight increase in patients younger than 55 years since 2005 (49.1% in 2005 to 56.6% in 2009) (Figure HT32).

The majority of total resurfacings use hybrid fixation (94.0% in 2009), however there has been an increase in the proportion of cementless fixation, increasing from 2.3% in 2003 to 5.8% in 2009. The bearing surface for resurfacing hip replacement is metal/metal in almost all cases.

The BHR remains the most used resurfacing hip prosthesis (68.1%) but is declining in use. The Mitch TRH, ASR and Durom have also shown a decline in use in 2009 (Table HT57).

Outcome

The cumulative percent revision at nine years for primary total resurfacing hip replacement undertaken for osteoarthritis is 7.2% (Table HT58 and Figure HT33).

Reasons for Revision

The main reasons for revision of primary resurfacing hip replacements are fracture (35.6%), loosening/lysis (33.4%), infection (8.2%), metal sensitivity (7.1%) and pain (5.3%) (Table HT59).

The five most common reasons for revision are shown in Figure HT34.

The incidence of revision for fracture increases rapidly in the first year, however after this time the incidence increases at a slower rate. Loosening/lysis shows a linear increase and at six years exceeds fracture to become the most common reason for revision. The remaining reasons for revision have a low incidence.

Type of Revision

The main types of revision of resurfacing hip replacement are isolated femoral (52.4%), total hip replacement (36.7%) and acetabular only (7.5%) (Table HT60).

Primary Diagnosis

The outcomes of the three most common primary diagnoses (osteoarthritis, developmental dysplasia and avascular necrosis) are listed in Tables HT61 and HT62.

Primary resurfacing hip replacement for osteoarthritis has a significantly lower risk of revisioncompared to developmental dysplasia (Figure HT35).


Age and Gender

There is a higher risk of revision for patients 65 years or older (Tables HT63 and HT64 and Figure HT36).

Females have twice the risk of revision compared to males (seven year cumulative percent revision of 9.3% and 4.5% respectively) (Tables HT65 and HT66 and Figure HT37).

There is no age related difference in the risk of revision for females. The age related revision risk is only associated with males (Tables HT67 and HT68 and Figures HT38 and HT39).

Head Size

As previously reported, there is a relationship between femoral component head size and the risk of revision. Head sizes of 44mm or less have more than six times the risk of revision compared to head sizes 55mm or greater (Tables HT69 and HT70 and Figure HT40).

The effect of femoral component head size is evident in both males and females. Gender difference in outcome for total resurfacing hip replacement is largely due to differences in femoral head size. There is no significant difference between gender in the risk of revision after adjusting for femoral component head size. Males and females with femoral component head size less than 50mm have a similar cumulative percent revision at seven years (10.2% and 10.3% respectively). Males and females with head sizes 50mm or greater also have a similar seven year cumulative percent revision (3.5% and 3.3% respectively) (Tables HT71 and HT72 and Figure HT41).

Revision diagnosis cumulative incidence varies with head size. Head sizes less then 50mm have a higher incidence of the five most common reasons for revision (Figure HT42).

 

 

Prosthesis Types

The revision rates and yearly cumulative percent revision of total resurfacing hip prostheses are listed in Tables HT73 and HT74.

There are five prostheses with over 1,000 observed component years, the BHR, ASR, Durom, Cormet and Mitch TRH. At five years, the BHR has the lowest cumulative percent revision (3.5%)compared to Cormet (6.0%), Durom (7.6%) and ASR (10.9%).

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