Risk factors for femoral stem breakage: an analysis of the AOANJRR results.

INTRODUCTION: Breakage of the femoral stem component of a total hip replacement is now uncommon but continues to be seen with certain stem designs and in certain patient groups. Data previously published on this topic has been limited, either gathered from a single surgeon or centre, or included only a single stem design. METHODS: We reviewed the data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), identified and analysed 143 stem breakages over a period of 16 years, covering 44 different stem designs. RESULTS: Our data confirms previously published findings that risk factors for stem breakage include patient age at implantation of under 70, male gender, as well as the use of exchangeable necks. We found no association with initial diagnosis, or type of acetabular component implanted. We did however also find, excluding exchangeable neck designs, that after 4.5 years a cemented stem had a significantly higher risk of breakage then a cementless stem. DISCUSSION: To our knowledge this is the 1st paper to suggest cemented fixation as a specific risk factor for stem breakage. The analysis of rare complications such as stem breakage is only possible through large data collection systems such as the AOANJRR. Whilst there have been recent advances in materials and manufacturing techniques, we recommend that surgeons are aware of all the specific risks when considering implant choices for individual patients.

Prevalence of developmental dysplasia of the hip in children with clubfoot.

PURPOSE: The relationship between congenital talipes equinovarus (CTEV) and developmental dysplasia of the hip (DDH) remains uncertain. The role of routine hip screening in children with CTEV is debated. A recent study has found a high incidence of DDH in patients with CTEV. The aim of our study was to determine the true prevalence of radiographic hip dysplasia and identify the need for routine hip screening in patients treated for CTEV. METHODS: From a single centre database of 165 children consisting of 260 CTEV, a prospective radiological prevalence study of 101 children was performed over a period of 3 months. A single anterior-posterior pelvic radiograph was performed at a minimum age of 5 months. The DDH was determined by a single senior investigator based on the age-adjusted acetabular index (AI) as described by Tonnis. RESULTS: There were no dislocations or subluxations. According to the age-adjusted AI, 16 children had 'light' dysplasia and one child had 'severe' dysplasia. The child with severe dysplasia was known to have DDH and had already undergone treatment. The 16 children with light dysplasia did not require any form of treatment. CONCLUSION: Out of one hundred and one children with CTEV, only one had DDH requiring treatment. This is consistent with the majority of the literature supporting the premise that there is no true association between CTEV and DDH. We, therefore, feel that routine hip screening for children with CTEV is not supported by current evidence and cannot be recommended.