Abstract
Introduction: Since 1975, 6 types of extendable endo-prostheses have been developed at Biomedical Engineering, UCL, and Stanmore Implants Worldwide in conjunction with the surgeons at this centre.
Aims: To establish whether developments in design have had the desired effect of improving both implant survivorship and functional outcome.
Methods: This was a retrospective study using case notes, hospital databases and a radiological review, combined with contemporary functional outcome assessments (MSTS, TESS, SF36).
Results: 161 consecutive prostheses in 138 paediatric patients, between the years of 1983 – 2005, were implanted for primary bone tumours. Mean age was 10.3 (3 – 18), 81 were males and 57 females. There were 136 primary procedures and 25 revisions.
6 prostheses that used ball bearings to achieve length (designed in 1981) were implanted, 3 (50 %) were revised due to mechanical failure.
19 prostheses that utilised external C-washes (1998) to achieve length were implanted, 6 (32 %) were revised, half of these for mechanical failure.
Of the 98 minimally invasive prostheses (1992) that utilized an Allan key and screw-jack mechanism to lengthen, 14 (14 %) were revised, half of these for infection.
17 non-invasive extendable endoprostheses (2001) that are lengthened by electromagnetic coupling have been implanted so far. There has only been 1 (6 %) revision. This was due to full extension being reached.
Conclusions: Design improvements in growing endoprostheses since 1983 have led to improved survivorship. Initially this led to a reduction in mechanical failure and latterly to a reduction in infection, as indications for revision.
Key Words: Bone tumour, children, endoprosthesis, survivorship.
The abstracts were prepared by Mrs Leslie O’Leary. Correspondence should be addressed to her at British Orthopaedic Association, 35–43 Lincoln’s Inn Fields, London WC2A 3PE or at l.oleary@boa.ac.uk
