Introduction There are no reports on the epidemiology of revision hip arthroplasty in Australia. The aim of this study was to characterise the epidemiology of revision hip arthroplasty in relation to primary hip replacements in Australia.

Methods This study covered the seven year period 1993/1994 to 1999/2000. Data on all primary hip replacements and revisions done were obtained from the Australian Institute of Health and Welfare using the ICD-9 (81.53) and ICD-10 (Block No. 1492) cartegorisation. The data was stratified by age (five year age groups), sex, year and state or territory. Log linear modelling was used to examine the rate of revision procedures out of the total number of procedures (primary and revision). The effects of gender, age and year were examined in a series of hierarchical log-rate models (Poisson Loglinear Regression).

Results For the period of the study there were 18,027 revision cases and 122,595 cases of primary hip replacement, representing a revision rate of 14%. The rate of increase of primary hip replacements was significantly higher than the rate of increase of revisions (t= −12.1, p< 0.0005). The number of primary hip replacements performed nationally increased by 810 (95% confidence intervals 658,964) a year. The number of revisions increased by only 62 (95% confidence intervals 21,104) a year. The proportion of revisions decreased by 0.3% per year as determined by regression analysis. The hierarchical log-rate models indicate significant interactions between age and gender and beween age and year.

Conclusions The number of primary and revision hip replacements has been increasing with time. The rate of increase of revision hip replacements has been lower. The proportion of hip replacements that are revisions has been gradually dropping, probably due to a greater increase in the number of primary hip replacements.

Introduction Ulnar nerve entrapment is the second commonest upper limb nerve entrapment syndrome. The purpose of this study was to determine the safety and efficacy of the Agee endoscopic system in ulnar nerve decompression at the elbow. This is the first report of its use in the elbow.

Methods Six preserved cadaveric elbow specimens were used. One surgeon performed the endoscopic releases via a three centimetre longitudinal incision between the medial epicondyle and olecranon. All six specimens were examined independently with loupe magnification. This was done by extending the original incision to 20 cm. The ulnar nerve was assessed with regard to adequate decompression. The branching of the ulnar nerve at the elbow, as well as the presevation of these branches after the endoscopic procedure, was also studied.

Results In all six specimens, the arcade of Struthers, the cubital tunnel retinaculum, and the flexor carpiulnaris aponeurosis were completely divided. There were an average of three motor branches to flexor carpiulnaris at a mean position of 21 mm distal to the medial epicondyle. Most of these were on the radial side of the nerve. The ulnar nerve was also found to give one to two sensory branches, at a mean position of nine millimetres proximal to the medial epicondyle. All the motor and sensory branches were found to be intact after the endoscopic procedure.

Conclusions This study shows that the Agee endoscopic system is both safe and effective. It is a relatively simple procedure but cadaveric practice is recommended to obtain familiarity with the technique and the endoscopic view of the anatomy.