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Outcome by Patient Characteristics

The cumulative percent revision at nine years for primary total conventional hip replacement undertaken for osteoarthritis is 5.2% (Table HT10 and Figure HT4).

Reason for Revision

The most common reasons for revisions of primary  total conventional hip replacement are loosening/lysis  (29.9%), followed by prostheses dislocation (27.6%),infection (16.7%), fracture (14.7%) and pain (2.0%) (Table HT11).

The Registry links loosening/lysis as they often occur in association, particularly in late revision, secondary to wear related inflammation. The aetiology of loosening however varies with time. Early revision with a diagnosis of loosening is usually a consequence of not obtaining adequate initial fixation.

The incidence of the five most common reasons for revision all increase with time, however the rate of increase varies depending on the reason for revision. Initially the incidence of revision for dislocation increases rapidly, however, after the first few months it increases at a slower rate. Loosening/lysis shows a linear increase and at three years exceeds dislocation to become the most common reason for revision. In a similar way to dislocation, infection and fracture show a high initial increase in incidence but to a lesser extent. Pain is the fifth most common reason for revision. It has a linear increase but the incidence remains low over the entire period (Figure HT5).

 

 

Type of Revision

The type of revision used is influenced by the reason for revision. As these change with time, the relative proportion of each type of revision will also change with time. Currently, the five most common types of revision of primary total conventional hip replacement recorded by the Registry are femoral only revision (29.3%), acetabular only (24.9%), head and insert (18.3%), femoral/acetabular (12.3%) and head only (5.6%) (Table HT12).

 

 

 

Primary Diagnosis

Eleven primary diagnoses for total conventional hip replacement have been reported to the Registry. The outcomes of the five most common (osteoarthritis, avascular necrosis, fractured neck of femur, rheumatoid arthritis and developmental dysplasia) are listed in Tables HT13 and HT14.

Primary total conventional hip replacement performed for osteoarthritis has a significantly lower risk of revision compared to avascular necrosis, fractured neck of femur and rheumatoid arthritis.

Osteoarthritis has a significantly lower risk of revision compared to developmental dysplasia in the first three months, but there is no difference after this time (Figure HT6).


Age and Gender

There is a significant difference in the risk of revision with respect to age (Tables HT15 and HT16 and Figure HT7).

Previously the Registry has not identified a difference in the risk of revision with respect to gender, however, this year it has identified a higher risk of revision for males after one and a half years (Tables HT17 and HT18 and Figure HT8).

As previously reported there continues to be a difference in the risk of revision between age within gender. For females, the risk of revision decreases with increasing age. Females under 55 years have the highest risk of revision at nine years (6.5%) compared to females 75 years or older (4.2%) (Tables HT19 and HT20 and Figure HT9).

The relationship between risk of revision and age is not apparent for males at nine years. Males under 55 years have a cumulative percent revision of 5.0% compared to 5.7% for males 75 years or older (Figure HT10).

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