The medium-term results of the Stanmore non-invasive extendible endoprosthesis in the treatment of paediatric bone tumours

N. E. Picardo, G. W. Blunn, A. S. Shekkeris, J. Meswania, W. J. Aston, R. C. Pollock, J. A. Skinner, S. R. Cannon, T. W. Briggs


In skeletally immature patients, resection of bone tumours and reconstruction of the lower limb often results in leg-length discrepancy. The Stanmore non-invasive extendible endoprosthesis, which uses electromagnetic induction, allows post-operative lengthening without anaesthesia. Between 2002 and 2009, 55 children with a mean age of 11.4 years (5 to 16) underwent reconstruction with this prosthesis; ten patients (18.2%) died of disseminated disease and one child underwent amputation due to infection. We reviewed 44 patients after a mean follow-up of 41.2 months (22 to 104). The mean Musculoskeletal Tumor Society score was 24.7 (8 to 30) and the Toronto Extremity Salvage score was 92.3% (55.2% to 99.0%). There was no local recurrence of tumour. Complications developed in 16 patients (29.1%) and ten (18.2%) underwent revision.

The mean length gained per patient was 38.6 mm (3.5 to 161.5), requiring a mean of 11.3 extensions (1 to 40), and ten component exchanges were performed in nine patients (16.4%) after attaining the maximum lengthening capacity of the implant. There were 11 patients (20%) who were skeletally mature at follow-up, ten of whom had equal leg lengths and nine had a full range of movement of the hip and knee.

This is the largest reported series using non-invasive extendible endoprostheses after excision of primary bone tumours in skeletally immature patients. The technique produces a good functional outcome, with prevention of limb-length discrepancy at skeletal maturity.


  • The authors would like to thank C. Henry, Specialist Sarcoma Nurse at the Royal National Orthopaedic Hospital, for her help and support.

    No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

  • Supplementary material. Three tables showing i) the details of the 16 patients with complications following the implantation of the non-invasive extendible endoprosthesis, ii) the details of the revision procedures required in ten patients and their functional scores post-revision, and iii) a comparison of outcome data of expanding endoprostheses for the treatment of paediatric bone malignancies from the literature, are available with the electronic version of this article on our website

  • Received June 14, 2011.
  • Accepted October 4, 2011.
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