2012 ANNUAL REPORT

Demographics

There have been 14,901 total resurfacing procedures reported to the Registry, an additional 603 procedures, compared to the last report.

The use of resurfacing hip replacement in Australia continues to decline. The number of procedures reported in 2011 was 39.7% less than in 2010 and 68.5% less compared to the peak in 2005.

Osteoarthritis is the principal diagnosis for total resurfacing hip replacement (95.0%), followed by developmental dysplasia (2.5%) and osteonecrosis (1.7%).

Most patients are male and the proportion of males has increased from 71.2% in 2003 to 94.3% in 2011

There continues to be a shift in the use of primary total resurfacing hip replacement to younger patients. The proportion of patients under the age of 55 years has continued to increase and accounted for 62.6% of all primary total resurfacing procedures in 2011. There has been a corresponding decrease in use for patients aged 55-64 years (Figure HT34).

The majority of total resurfacings use hybrid fixation (98.3% in 2011).

The BHR remains the most used resurfacing hip prosthesis in 2011. Although its use has declined in absolute numbers in 2011 the proportion of resurfacing procedures using BHR has increased from 62.6% in 2010 to 75.4% in 2011 (Table HT61).

BHR Results

The BHR resurfacing prosthesis has a cumulative percent revision at 11 years of 7.1%.

Note about Total Hp Replacement Information:

At 11 years, hybrid fixation has the lowest cumulative percent revision of 6.0% compared to cemented (7.2%) and cementless fixation (7.8%) (Information from 2012 National Registry under Total Hip Replacement Information)

Outcome

The cumulative percent revision at 11 years for primary total resurfacing hip replacement undertaken for osteoarthritis is 9.5% (Table HT62 and Figure HT35).

Reasons for Revision

The main reasons for revision of primary total resurfacing hip replacement are loosening/lysis (33.6%), fracture (25.7%), metal sensitivity (16.6%), infection (7.2%) and pain (6.0%) (Table HT63).

The five most common reasons for revision are shown in Figure HT36. 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 just over four years exceeds fracture to become the most common reason for revision. The incidence of revision for metal sensitivity continues to increase.

Type of Revision

The main types of revision of resurfacing hip replacement are total hip replacement (53.3%), isolated femoral (38.5%), and acetabular only (5.2%) (Table HT64). In previous reports the most common type of revision was femoral only revision. This year the Registry is reporting a change. Revision of both the acetabular and femoral components to a total conventional hip replacement is now the most common type of revision for resurfacing hip replacement.

Primary Diagnosis

The outcomes of the three most common primary diagnoses (osteoarthritis, developmental dysplasia and osteonecrosis) are listed in Tables HT65 and HT66. Primary total resurfacing hip replacement for osteoarthritis has a significantly lower rate of revision compared to developmental dysplasia (Figure HT37).

Age and Gender

There is a higher rate of revision for patients 65 years or older for the first six months, after this time there is no difference compared to the other age groups (Tables HT67 and HT68 and Figure HT38).

Females have an increased rate of revision compared to males. After six years, females have over four times the rate of revision compared to males (Tables HT69 and HT70 and Figure HT39). While there is no age related difference in the rate of revision for females (Tables HT71 and HT72 and Figure HT40), there is an age related revision rate associated with males. Males over the age of 65 years have an increased rate of revision compared to males less than 55 years for the first six months and for males between the ages of 55 to 64 years for the first three months only (Tables HT71 and HT72 and Figure HT41).

Head Size

There is a relationship between femoral component head size and the rate of revision. Femoral head sizes of 44mm or less have more than three times the rate of revision compared to head sizes 50-54mm. Head sizes 45-49mm have over twice the rate of revision compared to head sizes 50-54mm (Tables HT73 and HT74 and Figure HT42). The effect of femoral component head size is evident in both males and females. Females have an increased rate of revision independent of head size though this is only apparent in head sizes greater than or equal to 50mm after seven years (Tables HT75, HT76 and Figure HT43).

Revision diagnosis cumulative incidence varies with head size. Head sizes less than 50mm have a higher incidence of the five most common reasons for revision (Figure HT44).

Prosthesis Types

Revisions per 100 observed component years and yearly cumulative percent revision of total resurfacing hip prostheses are listed in Tables HT77 and HT78. There are seven prostheses with over 1,000 observed component years, the ASR, Adept, BHR, Cormet, Cormet 2000 Bi-coated, Durom and Mitch TRH. The BHR resurfacing prosthesis has a cumulative percent revision at 11 years of 7.1%.