Aims. Extendible endoprostheses have been available for more than 30
years and have become more sophisticated with time. The latest generation
is ‘non-invasive’ and can be lengthened with an external magnetic
force. Early results have shown a worryingly high rate of complications
such as infection. This study investigates the incidence of complications
and the need for further surgery in a cohort of patients with a
non-invasive growing endoprosthesis. Patients and Methods. Between 2003 and June 2014, 50 children (51 prostheses) had a
non-invasive growing prosthesis implanted for a primary bone sarcoma.
The minimum follow-up was 24 months for those who survived. Their
mean age was 10.4 years (6 to 14). The incidence of complications
and further surgery was documented. Results. The mean follow-up was 64 months (20 to 145). The overall survivorship
of the patients was 84% at three years and 70% at five years. Revision-free
survival was 81.7% at three years and 61.6% at five years with competing
risk analysis. Deep infection occurred in 19.6% of implants at a
mean of 12.5 months (0 to 55). Other complications were a failure
of the lengthening mechanism in five prostheses (9.8%) and breakage
of the implant in two (3.9%). Overall, there were 53 additional
operations (0 to 5 per patient). A total of seven patients (14%)
underwent amputation, three for local recurrence and four for infection.
Their mean limb length discrepancy was 4.3 mm (0 to 25) and mean Musculoskeletal
Tumor Society Score functional score was 26.5 (18 to 30) at the
final follow-up. Conclusions. When compared with previously published early results, this mid-term
series has shown continued good functional outcomes and compensation
for leg-length discrepancy. Infection is still the most common complication:
post-operative
